Device drivers infrastructure¶
The Basic Device Driver-Model Structures¶
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struct subsys_interface¶
interfaces to device functions
Definition:
struct subsys_interface {
const char *name;
const struct bus_type *subsys;
struct list_head node;
int (*add_dev)(struct device *dev, struct subsys_interface *sif);
void (*remove_dev)(struct device *dev, struct subsys_interface *sif);
};
Members
namename of the device function
subsyssubsystem of the devices to attach to
nodethe list of functions registered at the subsystem
add_devdevice hookup to device function handler
remove_devdevice hookup to device function handler
Description
Simple interfaces attached to a subsystem. Multiple interfaces can attach to a subsystem and its devices. Unlike drivers, they do not exclusively claim or control devices. Interfaces usually represent a specific functionality of a subsystem/class of devices.
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struct device_attribute¶
Interface for exporting device attributes.
Definition:
struct device_attribute {
struct attribute attr;
ssize_t (*show)(struct device *dev, struct device_attribute *attr, char *buf);
ssize_t (*store)(struct device *dev, struct device_attribute *attr, const char *buf, size_t count);
};
Members
attrsysfs attribute definition.
showShow handler.
storeStore handler.
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struct dev_ext_attribute¶
Exported device attribute with extra context.
Definition:
struct dev_ext_attribute {
struct device_attribute attr;
void *var;
};
Members
attrExported device attribute.
varPointer to context.
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DEVICE_ATTR¶
DEVICE_ATTR (_name, _mode, _show, _store)
Define a device attribute.
Parameters
_nameAttribute name.
_modeFile mode.
_showShow handler. Optional, but mandatory if attribute is readable.
_storeStore handler. Optional, but mandatory if attribute is writable.
Description
Convenience macro for defining a struct device_attribute.
For example, DEVICE_ATTR(foo, 0644, foo_show, foo_store); expands to:
struct device_attribute dev_attr_foo = {
.attr = { .name = "foo", .mode = 0644 },
.show = foo_show,
.store = foo_store,
};
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DEVICE_ATTR_PREALLOC¶
DEVICE_ATTR_PREALLOC (_name, _mode, _show, _store)
Define a preallocated device attribute.
Parameters
_nameAttribute name.
_modeFile mode.
_showShow handler. Optional, but mandatory if attribute is readable.
_storeStore handler. Optional, but mandatory if attribute is writable.
Description
Like DEVICE_ATTR(), but SYSFS_PREALLOC is set on _mode.
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DEVICE_ATTR_RW¶
DEVICE_ATTR_RW (_name)
Define a read-write device attribute.
Parameters
_nameAttribute name.
Description
Like DEVICE_ATTR(), but _mode is 0644, _show is <_name>_show,
and _store is <_name>_store.
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DEVICE_ATTR_ADMIN_RW¶
DEVICE_ATTR_ADMIN_RW (_name)
Define an admin-only read-write device attribute.
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DEVICE_ATTR_RO¶
DEVICE_ATTR_RO (_name)
Define a readable device attribute.
Parameters
_nameAttribute name.
Description
Like DEVICE_ATTR(), but _mode is 0444 and _show is <_name>_show.
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DEVICE_ATTR_ADMIN_RO¶
DEVICE_ATTR_ADMIN_RO (_name)
Define an admin-only readable device attribute.
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DEVICE_ATTR_WO¶
DEVICE_ATTR_WO (_name)
Define an admin-only writable device attribute.
Parameters
_nameAttribute name.
Description
Like DEVICE_ATTR(), but _mode is 0200 and _store is <_name>_store.
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DEVICE_ULONG_ATTR¶
DEVICE_ULONG_ATTR (_name, _mode, _var)
Define a device attribute backed by an unsigned long.
Parameters
_nameAttribute name.
_modeFile mode.
_varIdentifier of unsigned long.
Description
Like DEVICE_ATTR(), but _show and _store are automatically provided
such that reads and writes to the attribute from userspace affect _var.
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DEVICE_INT_ATTR¶
DEVICE_INT_ATTR (_name, _mode, _var)
Define a device attribute backed by an int.
Parameters
_nameAttribute name.
_modeFile mode.
_varIdentifier of int.
Description
Like DEVICE_ULONG_ATTR(), but _var is an int.
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DEVICE_BOOL_ATTR¶
DEVICE_BOOL_ATTR (_name, _mode, _var)
Define a device attribute backed by a bool.
Parameters
_nameAttribute name.
_modeFile mode.
_varIdentifier of bool.
Description
Like DEVICE_ULONG_ATTR(), but _var is a bool.
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DEVICE_STRING_ATTR_RO¶
DEVICE_STRING_ATTR_RO (_name, _mode, _var)
Define a device attribute backed by a r/o string.
Parameters
_nameAttribute name.
_modeFile mode.
_varIdentifier of string.
Description
Like DEVICE_ULONG_ATTR(), but _var is a string. Because the length of the
string allocation is unknown, the attribute must be read-only.
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devm_alloc_percpu¶
devm_alloc_percpu (dev, type)
Resource-managed alloc_percpu
Parameters
devDevice to allocate per-cpu memory for
typeType to allocate per-cpu memory for
Description
Managed alloc_percpu. Per-cpu memory allocated with this function is automatically freed on driver detach.
Return
Pointer to allocated memory on success, NULL on failure.
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enum dl_dev_state¶
Device driver presence tracking information.
Constants
DL_DEV_NO_DRIVERThere is no driver attached to the device.
DL_DEV_PROBINGA driver is probing.
DL_DEV_DRIVER_BOUNDThe driver has been bound to the device.
DL_DEV_UNBINDINGThe driver is unbinding from the device.
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enum device_removable¶
Whether the device is removable. The criteria for a device to be classified as removable is determined by its subsystem or bus.
Constants
DEVICE_REMOVABLE_NOT_SUPPORTEDThis attribute is not supported for this device (default).
DEVICE_REMOVABLE_UNKNOWNDevice location is Unknown.
DEVICE_FIXEDDevice is not removable by the user.
DEVICE_REMOVABLEDevice is removable by the user.
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struct dev_links_info¶
Device data related to device links.
Definition:
struct dev_links_info {
struct list_head suppliers;
struct list_head consumers;
struct list_head defer_sync;
enum dl_dev_state status;
};
Members
suppliersList of links to supplier devices.
consumersList of links to consumer devices.
defer_syncHook to global list of devices that have deferred sync_state.
statusDriver status information.
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struct dev_msi_info¶
Device data related to MSI
Definition:
struct dev_msi_info {
#ifdef CONFIG_GENERIC_MSI_IRQ;
struct irq_domain *domain;
struct msi_device_data *data;
#endif;
};
Members
domainThe MSI interrupt domain associated to the device
dataPointer to MSI device data
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enum device_physical_location_panel¶
Describes which panel surface of the system’s housing the device connection point resides on.
Constants
DEVICE_PANEL_TOPDevice connection point is on the top panel.
DEVICE_PANEL_BOTTOMDevice connection point is on the bottom panel.
DEVICE_PANEL_LEFTDevice connection point is on the left panel.
DEVICE_PANEL_RIGHTDevice connection point is on the right panel.
DEVICE_PANEL_FRONTDevice connection point is on the front panel.
DEVICE_PANEL_BACKDevice connection point is on the back panel.
DEVICE_PANEL_UNKNOWNThe panel with device connection point is unknown.
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enum device_physical_location_vertical_position¶
Describes vertical position of the device connection point on the panel surface.
Constants
DEVICE_VERT_POS_UPPERDevice connection point is at upper part of panel.
DEVICE_VERT_POS_CENTERDevice connection point is at center part of panel.
DEVICE_VERT_POS_LOWERDevice connection point is at lower part of panel.
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enum device_physical_location_horizontal_position¶
Describes horizontal position of the device connection point on the panel surface.
Constants
DEVICE_HORI_POS_LEFTDevice connection point is at left part of panel.
DEVICE_HORI_POS_CENTERDevice connection point is at center part of panel.
DEVICE_HORI_POS_RIGHTDevice connection point is at right part of panel.
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struct device_physical_location¶
Device data related to physical location of the device connection point.
Definition:
struct device_physical_location {
enum device_physical_location_panel panel;
enum device_physical_location_vertical_position vertical_position;
enum device_physical_location_horizontal_position horizontal_position;
bool dock;
bool lid;
};
Members
panelPanel surface of the system’s housing that the device connection point resides on.
vertical_positionVertical position of the device connection point within the panel.
horizontal_positionHorizontal position of the device connection point within the panel.
dockSet if the device connection point resides in a docking station or port replicator.
lidSet if this device connection point resides on the lid of laptop system.
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struct device¶
The basic device structure
Definition:
struct device {
struct kobject kobj;
struct device *parent;
struct device_private *p;
const char *init_name;
const struct device_type *type;
const struct bus_type *bus;
struct device_driver *driver;
void *platform_data;
void *driver_data;
struct mutex mutex;
struct dev_links_info links;
struct dev_pm_info power;
struct dev_pm_domain *pm_domain;
#ifdef CONFIG_ENERGY_MODEL;
struct em_perf_domain *em_pd;
#endif;
#ifdef CONFIG_PINCTRL;
struct dev_pin_info *pins;
#endif;
struct dev_msi_info msi;
#ifdef CONFIG_DMA_OPS;
const struct dma_map_ops *dma_ops;
#endif;
u64 *dma_mask;
u64 coherent_dma_mask;
u64 bus_dma_limit;
const struct bus_dma_region *dma_range_map;
struct device_dma_parameters *dma_parms;
struct list_head dma_pools;
#ifdef CONFIG_DMA_DECLARE_COHERENT;
struct dma_coherent_mem *dma_mem;
#endif;
#ifdef CONFIG_DMA_CMA;
struct cma *cma_area;
#endif;
#ifdef CONFIG_SWIOTLB;
struct io_tlb_mem *dma_io_tlb_mem;
#endif;
#ifdef CONFIG_SWIOTLB_DYNAMIC;
struct list_head dma_io_tlb_pools;
spinlock_t dma_io_tlb_lock;
bool dma_uses_io_tlb;
#endif;
struct dev_archdata archdata;
struct device_node *of_node;
struct fwnode_handle *fwnode;
#ifdef CONFIG_NUMA;
int numa_node;
#endif;
dev_t devt;
u32 id;
spinlock_t devres_lock;
struct list_head devres_head;
const struct class *class;
const struct attribute_group **groups;
void (*release)(struct device *dev);
struct iommu_group *iommu_group;
struct dev_iommu *iommu;
struct device_physical_location *physical_location;
enum device_removable removable;
bool offline_disabled:1;
bool offline:1;
bool of_node_reused:1;
bool state_synced:1;
bool can_match:1;
#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL);
bool dma_coherent:1;
#endif;
#ifdef CONFIG_DMA_OPS_BYPASS;
bool dma_ops_bypass : 1;
#endif;
#ifdef CONFIG_DMA_NEED_SYNC;
bool dma_skip_sync:1;
#endif;
};
Members
kobjA top-level, abstract class from which other classes are derived.
parentThe device’s “parent” device, the device to which it is attached. In most cases, a parent device is some sort of bus or host controller. If parent is NULL, the device, is a top-level device, which is not usually what you want.
pHolds the private data of the driver core portions of the device. See the comment of the struct device_private for detail.
init_nameInitial name of the device.
typeThe type of device. This identifies the device type and carries type-specific information.
busType of bus device is on.
driverWhich driver has allocated this
platform_dataPlatform data specific to the device.
driver_dataPrivate pointer for driver specific info.
mutexMutex to synchronize calls to its driver.
linksLinks to suppliers and consumers of this device.
powerFor device power management. See Device Power Management Basics for details.
pm_domainProvide callbacks that are executed during system suspend, hibernation, system resume and during runtime PM transitions along with subsystem-level and driver-level callbacks.
em_pddevice’s energy model performance domain
pinsFor device pin management. See PINCTRL (PIN CONTROL) subsystem for details.
msiMSI related data
dma_opsDMA mapping operations for this device.
dma_maskDma mask (if dma’ble device).
coherent_dma_maskLike dma_mask, but for alloc_coherent mapping as not all hardware supports 64-bit addresses for consistent allocations such descriptors.
bus_dma_limitLimit of an upstream bridge or bus which imposes a smaller DMA limit than the device itself supports.
dma_range_mapmap for DMA memory ranges relative to that of RAM
dma_parmsA low level driver may set these to teach IOMMU code about segment limitations.
dma_poolsDma pools (if dma’ble device).
dma_memInternal for coherent mem override.
cma_areaContiguous memory area for dma allocations
dma_io_tlb_memSoftware IO TLB allocator. Not for driver use.
dma_io_tlb_poolsList of transient swiotlb memory pools.
dma_io_tlb_lockProtects changes to the list of active pools.
dma_uses_io_tlbtrueif device has used the software IO TLB.archdataFor arch-specific additions.
of_nodeAssociated device tree node.
fwnodeAssociated device node supplied by platform firmware.
numa_nodeNUMA node this device is close to.
devtFor creating the sysfs “dev”.
iddevice instance
devres_lockSpinlock to protect the resource of the device.
devres_headThe resources list of the device.
classThe class of the device.
groupsOptional attribute groups.
releaseCallback to free the device after all references have gone away. This should be set by the allocator of the device (i.e. the bus driver that discovered the device).
iommu_groupIOMMU group the device belongs to.
iommuPer device generic IOMMU runtime data
physical_locationDescribes physical location of the device connection point in the system housing.
removableWhether the device can be removed from the system. This should be set by the subsystem / bus driver that discovered the device.
offline_disabledIf set, the device is permanently online.
offlineSet after successful invocation of bus type’s .offline().
of_node_reusedSet if the device-tree node is shared with an ancestor device.
state_syncedThe hardware state of this device has been synced to match the software state of this device by calling the driver/bus sync_state() callback.
can_matchThe device has matched with a driver at least once or it is in a bus (like AMBA) which can’t check for matching drivers until other devices probe successfully.
dma_coherentthis particular device is dma coherent, even if the architecture supports non-coherent devices.
dma_ops_bypassIf set to
truethen the dma_ops are bypassed for the streaming DMA operations (->map_* / ->unmap_* / ->sync_*), and optionall (if the coherent mask is large enough) also for dma allocations. This flag is managed by the dma ops instance from ->dma_supported.dma_skip_syncDMA sync operations can be skipped for coherent buffers.
Example
- For devices on custom boards, as typical of embedded
and SOC based hardware, Linux often uses platform_data to point to board-specific structures describing devices and how they are wired. That can include what ports are available, chip variants, which GPIO pins act in what additional roles, and so on. This shrinks the “Board Support Packages” (BSPs) and minimizes board-specific #ifdefs in drivers.
Description
At the lowest level, every device in a Linux system is represented by an
instance of struct device. The device structure contains the information
that the device model core needs to model the system. Most subsystems,
however, track additional information about the devices they host. As a
result, it is rare for devices to be represented by bare device structures;
instead, that structure, like kobject structures, is usually embedded within
a higher-level representation of the device.
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struct device_link¶
Device link representation.
Definition:
struct device_link {
struct device *supplier;
struct list_head s_node;
struct device *consumer;
struct list_head c_node;
struct device link_dev;
enum device_link_state status;
u32 flags;
refcount_t rpm_active;
struct kref kref;
struct work_struct rm_work;
bool supplier_preactivated;
};
Members
supplierThe device on the supplier end of the link.
s_nodeHook to the supplier device’s list of links to consumers.
consumerThe device on the consumer end of the link.
c_nodeHook to the consumer device’s list of links to suppliers.
link_devdevice used to expose link details in sysfs
statusThe state of the link (with respect to the presence of drivers).
flagsLink flags.
rpm_activeWhether or not the consumer device is runtime-PM-active.
krefCount repeated addition of the same link.
rm_workWork structure used for removing the link.
supplier_preactivatedSupplier has been made active before consumer probe.
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bool device_iommu_mapped(struct device *dev)¶
Returns true when the device DMA is translated by an IOMMU
Parameters
struct device *devDevice to perform the check on
Parameters
const struct device *devDevice with name to get.
Return
The kobject name of the device, or its initial name if unavailable.
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const char *dev_bus_name(const struct device *dev)¶
Return a device’s bus/class name, if at all possible
Parameters
const struct device *devstruct deviceto get the bus/class name of
Description
Will return the name of the bus/class the device is attached to. If it is not attached to a bus/class, an empty string will be returned.
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device_lock_set_class¶
device_lock_set_class (dev, key)
Specify a temporary lock class while a device is attached to a driver
Parameters
devdevice to modify
keylock class key data
Description
This must be called with the device_lock() already held, for example from driver ->probe(). Take care to only override the default lockdep_no_validate class.
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device_lock_reset_class¶
device_lock_reset_class (dev)
Return a device to the default lockdep novalidate state
Parameters
devdevice to modify
Description
This must be called with the device_lock() already held, for example from driver ->remove().
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struct bus_type¶
The bus type of the device
Definition:
struct bus_type {
const char *name;
const char *dev_name;
const struct attribute_group **bus_groups;
const struct attribute_group **dev_groups;
const struct attribute_group **drv_groups;
int (*match)(struct device *dev, struct device_driver *drv);
int (*uevent)(const struct device *dev, struct kobj_uevent_env *env);
int (*probe)(struct device *dev);
void (*sync_state)(struct device *dev);
void (*remove)(struct device *dev);
void (*shutdown)(struct device *dev);
int (*online)(struct device *dev);
int (*offline)(struct device *dev);
int (*suspend)(struct device *dev, pm_message_t state);
int (*resume)(struct device *dev);
int (*num_vf)(struct device *dev);
int (*dma_configure)(struct device *dev);
void (*dma_cleanup)(struct device *dev);
const struct dev_pm_ops *pm;
bool need_parent_lock;
};
Members
nameThe name of the bus.
dev_nameUsed for subsystems to enumerate devices like (“foo``u``”, dev->id).
bus_groupsDefault attributes of the bus.
dev_groupsDefault attributes of the devices on the bus.
drv_groupsDefault attributes of the device drivers on the bus.
matchCalled, perhaps multiple times, whenever a new device or driver is added for this bus. It should return a positive value if the given device can be handled by the given driver and zero otherwise. It may also return error code if determining that the driver supports the device is not possible. In case of -EPROBE_DEFER it will queue the device for deferred probing.
ueventCalled when a device is added, removed, or a few other things that generate uevents to add the environment variables.
probeCalled when a new device or driver add to this bus, and callback the specific driver’s probe to initial the matched device.
sync_stateCalled to sync device state to software state after all the state tracking consumers linked to this device (present at the time of late_initcall) have successfully bound to a driver. If the device has no consumers, this function will be called at late_initcall_sync level. If the device has consumers that are never bound to a driver, this function will never get called until they do.
removeCalled when a device removed from this bus.
shutdownCalled at shut-down time to quiesce the device.
onlineCalled to put the device back online (after offlining it).
offlineCalled to put the device offline for hot-removal. May fail.
suspendCalled when a device on this bus wants to go to sleep mode.
resumeCalled to bring a device on this bus out of sleep mode.
num_vfCalled to find out how many virtual functions a device on this bus supports.
dma_configureCalled to setup DMA configuration on a device on this bus.
dma_cleanupCalled to cleanup DMA configuration on a device on this bus.
pmPower management operations of this bus, callback the specific device driver’s pm-ops.
need_parent_lockWhen probing or removing a device on this bus, the device core should lock the device’s parent.
Description
A bus is a channel between the processor and one or more devices. For the purposes of the device model, all devices are connected via a bus, even if it is an internal, virtual, “platform” bus. Buses can plug into each other. A USB controller is usually a PCI device, for example. The device model represents the actual connections between buses and the devices they control. A bus is represented by the bus_type structure. It contains the name, the default attributes, the bus’ methods, PM operations, and the driver core’s private data.
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enum bus_notifier_event¶
Bus Notifier events that have happened
Constants
BUS_NOTIFY_ADD_DEVICEdevice is added to this bus
BUS_NOTIFY_DEL_DEVICEdevice is about to be removed from this bus
BUS_NOTIFY_REMOVED_DEVICEdevice is successfully removed from this bus
BUS_NOTIFY_BIND_DRIVERa driver is about to be bound to this device on this bus
BUS_NOTIFY_BOUND_DRIVERa driver is successfully bound to this device on this bus
BUS_NOTIFY_UNBIND_DRIVERa driver is about to be unbound from this device on this bus
BUS_NOTIFY_UNBOUND_DRIVERa driver is successfully unbound from this device on this bus
BUS_NOTIFY_DRIVER_NOT_BOUNDa driver failed to be bound to this device on this bus
Description
These are the value passed to a bus notifier when a specific event happens.
Note that bus notifiers are likely to be called with the device lock already held by the driver core, so be careful in any notifier callback as to what you do with the device structure.
All bus notifiers are called with the target struct device * as an argument.
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struct class¶
device classes
Definition:
struct class {
const char *name;
const struct attribute_group **class_groups;
const struct attribute_group **dev_groups;
int (*dev_uevent)(const struct device *dev, struct kobj_uevent_env *env);
char *(*devnode)(const struct device *dev, umode_t *mode);
void (*class_release)(const struct class *class);
void (*dev_release)(struct device *dev);
int (*shutdown_pre)(struct device *dev);
const struct kobj_ns_type_operations *ns_type;
const void *(*namespace)(const struct device *dev);
void (*get_ownership)(const struct device *dev, kuid_t *uid, kgid_t *gid);
const struct dev_pm_ops *pm;
};
Members
nameName of the class.
class_groupsDefault attributes of this class.
dev_groupsDefault attributes of the devices that belong to the class.
dev_ueventCalled when a device is added, removed from this class, or a few other things that generate uevents to add the environment variables.
devnodeCallback to provide the devtmpfs.
class_releaseCalled to release this class.
dev_releaseCalled to release the device.
shutdown_preCalled at shut-down time before driver shutdown.
ns_typeCallbacks so sysfs can detemine namespaces.
namespaceNamespace of the device belongs to this class.
get_ownershipAllows class to specify uid/gid of the sysfs directories for the devices belonging to the class. Usually tied to device’s namespace.
pmThe default device power management operations of this class.
Description
A class is a higher-level view of a device that abstracts out low-level implementation details. Drivers may see a SCSI disk or an ATA disk, but, at the class level, they are all simply disks. Classes allow user space to work with devices based on what they do, rather than how they are connected or how they work.
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enum probe_type¶
device driver probe type to try Device drivers may opt in for special handling of their respective probe routines. This tells the core what to expect and prefer.
Constants
PROBE_DEFAULT_STRATEGYUsed by drivers that work equally well whether probed synchronously or asynchronously.
PROBE_PREFER_ASYNCHRONOUSDrivers for “slow” devices which probing order is not essential for booting the system may opt into executing their probes asynchronously.
PROBE_FORCE_SYNCHRONOUSUse this to annotate drivers that need their probe routines to run synchronously with driver and device registration (with the exception of -EPROBE_DEFER handling - re-probing always ends up being done asynchronously).
Description
Note that the end goal is to switch the kernel to use asynchronous
probing by default, so annotating drivers with
PROBE_PREFER_ASYNCHRONOUS is a temporary measure that allows us
to speed up boot process while we are validating the rest of the
drivers.
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struct device_driver¶
The basic device driver structure
Definition:
struct device_driver {
const char *name;
const struct bus_type *bus;
struct module *owner;
const char *mod_name;
bool suppress_bind_attrs;
enum probe_type probe_type;
const struct of_device_id *of_match_table;
const struct acpi_device_id *acpi_match_table;
int (*probe) (struct device *dev);
void (*sync_state)(struct device *dev);
int (*remove) (struct device *dev);
void (*shutdown) (struct device *dev);
int (*suspend) (struct device *dev, pm_message_t state);
int (*resume) (struct device *dev);
const struct attribute_group **groups;
const struct attribute_group **dev_groups;
const struct dev_pm_ops *pm;
void (*coredump) (struct device *dev);
struct driver_private *p;
};
Members
nameName of the device driver.
busThe bus which the device of this driver belongs to.
ownerThe module owner.
mod_nameUsed for built-in modules.
suppress_bind_attrsDisables bind/unbind via sysfs.
probe_typeType of the probe (synchronous or asynchronous) to use.
of_match_tableThe open firmware table.
acpi_match_tableThe ACPI match table.
probeCalled to query the existence of a specific device, whether this driver can work with it, and bind the driver to a specific device.
sync_stateCalled to sync device state to software state after all the state tracking consumers linked to this device (present at the time of late_initcall) have successfully bound to a driver. If the device has no consumers, this function will be called at late_initcall_sync level. If the device has consumers that are never bound to a driver, this function will never get called until they do.
removeCalled when the device is removed from the system to unbind a device from this driver.
shutdownCalled at shut-down time to quiesce the device.
suspendCalled to put the device to sleep mode. Usually to a low power state.
resumeCalled to bring a device from sleep mode.
groupsDefault attributes that get created by the driver core automatically.
dev_groupsAdditional attributes attached to device instance once it is bound to the driver.
pmPower management operations of the device which matched this driver.
coredumpCalled when sysfs entry is written to. The device driver is expected to call the dev_coredump API resulting in a uevent.
pDriver core’s private data, no one other than the driver core can touch this.
Description
The device driver-model tracks all of the drivers known to the system. The main reason for this tracking is to enable the driver core to match up drivers with new devices. Once drivers are known objects within the system, however, a number of other things become possible. Device drivers can export information and configuration variables that are independent of any specific device.
Device Drivers Base¶
-
void driver_init(void)¶
initialize driver model.
Parameters
voidno arguments
Description
Call the driver model init functions to initialize their subsystems. Called early from init/main.c.
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struct device *driver_find_device_by_name(struct device_driver *drv, const char *name)¶
device iterator for locating a particular device of a specific name.
Parameters
struct device_driver *drvthe driver we’re iterating
const char *namename of the device to match
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struct device *driver_find_device_by_of_node(struct device_driver *drv, const struct device_node *np)¶
device iterator for locating a particular device by of_node pointer.
Parameters
struct device_driver *drvthe driver we’re iterating
const struct device_node *npof_node pointer to match.
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struct device *driver_find_device_by_fwnode(struct device_driver *drv, const struct fwnode_handle *fwnode)¶
device iterator for locating a particular device by fwnode pointer.
Parameters
struct device_driver *drvthe driver we’re iterating
const struct fwnode_handle *fwnodefwnode pointer to match.
-
struct device *driver_find_device_by_devt(struct device_driver *drv, dev_t devt)¶
device iterator for locating a particular device by devt.
Parameters
struct device_driver *drvthe driver we’re iterating
dev_t devtdevt pointer to match.
-
struct device *driver_find_device_by_acpi_dev(struct device_driver *drv, const struct acpi_device *adev)¶
device iterator for locating a particular device matching the ACPI_COMPANION device.
Parameters
struct device_driver *drvthe driver we’re iterating
const struct acpi_device *adevACPI_COMPANION device to match.
-
module_driver¶
module_driver (__driver, __register, __unregister, ...)
Helper macro for drivers that don’t do anything special in module init/exit. This eliminates a lot of boilerplate. Each module may only use this macro once, and calling it replaces
module_init()andmodule_exit().
Parameters
__driverdriver name
__registerregister function for this driver type
__unregisterunregister function for this driver type
...Additional arguments to be passed to __register and __unregister.
Description
Use this macro to construct bus specific macros for registering drivers, and do not use it on its own.
-
builtin_driver¶
builtin_driver (__driver, __register, ...)
Helper macro for drivers that don’t do anything special in init and have no exit. This eliminates some boilerplate. Each driver may only use this macro once, and calling it replaces device_initcall (or in some cases, the legacy __initcall). This is meant to be a direct parallel of
module_driver()above but without the __exit stuff that is not used for builtin cases.
Parameters
__driverdriver name
__registerregister function for this driver type
...Additional arguments to be passed to __register
Description
Use this macro to construct bus specific macros for registering drivers, and do not use it on its own.
-
int driver_set_override(struct device *dev, const char **override, const char *s, size_t len)¶
Helper to set or clear driver override.
Parameters
struct device *devDevice to change
const char **overrideAddress of string to change (e.g.
device->driver_override); The contents will be freed and hold newly allocated override.const char *sNUL-terminated string, new driver name to force a match, pass empty string to clear it (”” or “n”, where the latter is only for sysfs interface).
size_t lenlength of s
Description
Helper to set or clear driver override in a device, intended for the cases when the driver_override field is allocated by driver/bus code.
Return
0 on success or a negative error code on failure.
-
int driver_for_each_device(struct device_driver *drv, struct device *start, void *data, int (*fn)(struct device*, void*))¶
Iterator for devices bound to a driver.
Parameters
struct device_driver *drvDriver we’re iterating.
struct device *startDevice to begin with
void *dataData to pass to the callback.
int (*fn)(struct device *, void *)Function to call for each device.
Description
Iterate over the drv’s list of devices calling fn for each one.
-
struct device *driver_find_device(struct device_driver *drv, struct device *start, const void *data, int (*match)(struct device *dev, const void *data))¶
device iterator for locating a particular device.
Parameters
struct device_driver *drvThe device’s driver
struct device *startDevice to begin with
const void *dataData to pass to match function
int (*match)(struct device *dev, const void *data)Callback function to check device
Description
This is similar to the driver_for_each_device() function above, but
it returns a reference to a device that is ‘found’ for later use, as
determined by the match callback.
The callback should return 0 if the device doesn’t match and non-zero if it does. If the callback returns non-zero, this function will return to the caller and not iterate over any more devices.
-
int driver_create_file(struct device_driver *drv, const struct driver_attribute *attr)¶
create sysfs file for driver.
Parameters
struct device_driver *drvdriver.
const struct driver_attribute *attrdriver attribute descriptor.
-
void driver_remove_file(struct device_driver *drv, const struct driver_attribute *attr)¶
remove sysfs file for driver.
Parameters
struct device_driver *drvdriver.
const struct driver_attribute *attrdriver attribute descriptor.
-
int driver_register(struct device_driver *drv)¶
register driver with bus
Parameters
struct device_driver *drvdriver to register
Description
We pass off most of the work to the bus_add_driver() call, since most of the things we have to do deal with the bus structures.
-
void driver_unregister(struct device_driver *drv)¶
remove driver from system.
Parameters
struct device_driver *drvdriver.
Description
Again, we pass off most of the work to the bus-level call.
-
void device_link_wait_removal(void)¶
Wait for ongoing devlink removal jobs to terminate
Parameters
voidno arguments
-
struct device_link *device_link_add(struct device *consumer, struct device *supplier, u32 flags)¶
Create a link between two devices.
Parameters
struct device *consumerConsumer end of the link.
struct device *supplierSupplier end of the link.
u32 flagsLink flags.
Description
The caller is responsible for the proper synchronization of the link creation with runtime PM. First, setting the DL_FLAG_PM_RUNTIME flag will cause the runtime PM framework to take the link into account. Second, if the DL_FLAG_RPM_ACTIVE flag is set in addition to it, the supplier devices will be forced into the active meta state and reference-counted upon the creation of the link. If DL_FLAG_PM_RUNTIME is not set, DL_FLAG_RPM_ACTIVE will be ignored.
If DL_FLAG_STATELESS is set in flags, the caller of this function is
expected to release the link returned by it directly with the help of either
device_link_del() or device_link_remove().
If that flag is not set, however, the caller of this function is handing the management of the link over to the driver core entirely and its return value can only be used to check whether or not the link is present. In that case, the DL_FLAG_AUTOREMOVE_CONSUMER and DL_FLAG_AUTOREMOVE_SUPPLIER device link flags can be used to indicate to the driver core when the link can be safely deleted. Namely, setting one of them in flags indicates to the driver core that the link is not going to be used (by the given caller of this function) after unbinding the consumer or supplier driver, respectively, from its device, so the link can be deleted at that point. If none of them is set, the link will be maintained until one of the devices pointed to by it (either the consumer or the supplier) is unregistered.
Also, if DL_FLAG_STATELESS, DL_FLAG_AUTOREMOVE_CONSUMER and DL_FLAG_AUTOREMOVE_SUPPLIER are not set in flags (that is, a persistent managed device link is being added), the DL_FLAG_AUTOPROBE_CONSUMER flag can be used to request the driver core to automatically probe for a consumer driver after successfully binding a driver to the supplier device.
The combination of DL_FLAG_STATELESS and one of DL_FLAG_AUTOREMOVE_CONSUMER, DL_FLAG_AUTOREMOVE_SUPPLIER, or DL_FLAG_AUTOPROBE_CONSUMER set in flags at the same time is invalid and will cause NULL to be returned upfront. However, if a device link between the given consumer and supplier pair exists already when this function is called for them, the existing link will be returned regardless of its current type and status (the link’s flags may be modified then). The caller of this function is then expected to treat the link as though it has just been created, so (in particular) if DL_FLAG_STATELESS was passed in flags, the link needs to be released explicitly when not needed any more (as stated above).
A side effect of the link creation is re-ordering of dpm_list and the devices_kset list by moving the consumer device and all devices depending on it to the ends of these lists (that does not happen to devices that have not been registered when this function is called).
The supplier device is required to be registered when this function is called and NULL will be returned if that is not the case. The consumer device need not be registered, however.
-
void device_link_del(struct device_link *link)¶
Delete a stateless link between two devices.
Parameters
struct device_link *linkDevice link to delete.
Description
The caller must ensure proper synchronization of this function with runtime
PM. If the link was added multiple times, it needs to be deleted as often.
Care is required for hotplugged devices: Their links are purged on removal
and calling device_link_del() is then no longer allowed.
-
void device_link_remove(void *consumer, struct device *supplier)¶
Delete a stateless link between two devices.
Parameters
void *consumerConsumer end of the link.
struct device *supplierSupplier end of the link.
Description
The caller must ensure proper synchronization of this function with runtime PM.
-
const char *dev_driver_string(const struct device *dev)¶
Return a device’s driver name, if at all possible
Parameters
const struct device *devstruct deviceto get the name of
Description
Will return the device’s driver’s name if it is bound to a device. If the device is not bound to a driver, it will return the name of the bus it is attached to. If it is not attached to a bus either, an empty string will be returned.
-
int devm_device_add_group(struct device *dev, const struct attribute_group *grp)¶
given a device, create a managed attribute group
Parameters
struct device *devThe device to create the group for
const struct attribute_group *grpThe attribute group to create
Description
This function creates a group for the first time. It will explicitly warn and error if any of the attribute files being created already exist.
Returns 0 on success or error code on failure.
-
int device_create_file(struct device *dev, const struct device_attribute *attr)¶
create sysfs attribute file for device.
Parameters
struct device *devdevice.
const struct device_attribute *attrdevice attribute descriptor.
-
void device_remove_file(struct device *dev, const struct device_attribute *attr)¶
remove sysfs attribute file.
Parameters
struct device *devdevice.
const struct device_attribute *attrdevice attribute descriptor.
-
bool device_remove_file_self(struct device *dev, const struct device_attribute *attr)¶
remove sysfs attribute file from its own method.
Parameters
struct device *devdevice.
const struct device_attribute *attrdevice attribute descriptor.
Description
See kernfs_remove_self() for details.
-
int device_create_bin_file(struct device *dev, const struct bin_attribute *attr)¶
create sysfs binary attribute file for device.
Parameters
struct device *devdevice.
const struct bin_attribute *attrdevice binary attribute descriptor.
-
void device_remove_bin_file(struct device *dev, const struct bin_attribute *attr)¶
remove sysfs binary attribute file
Parameters
struct device *devdevice.
const struct bin_attribute *attrdevice binary attribute descriptor.
Parameters
struct device *devdevice.
Description
This prepares the device for use by other layers by initializing
its fields.
It is the first half of device_register(), if called by
that function, though it can also be called separately, so one
may use dev’s fields. In particular, get_device()/put_device()
may be used for reference counting of dev after calling this
function.
All fields in dev must be initialized by the caller to 0, except
for those explicitly set to some other value. The simplest
approach is to use kzalloc() to allocate the structure containing
dev.
NOTE
Use put_device() to give up your reference instead of freeing
dev directly once you have called this function.
Parameters
struct device *devdevice
const char *fmtformat string for the device’s name
...variable arguments
Parameters
struct device *devdevice.
Description
This is part 2 of device_register(), though may be called
separately _iff_ device_initialize() has been called separately.
This adds dev to the kobject hierarchy via kobject_add(), adds it
to the global and sibling lists for the device, then
adds it to the other relevant subsystems of the driver model.
Do not call this routine or device_register() more than once for
any device structure. The driver model core is not designed to work
with devices that get unregistered and then spring back to life.
(Among other things, it’s very hard to guarantee that all references
to the previous incarnation of dev have been dropped.) Allocate
and register a fresh new struct device instead.
Rule of thumb is: if device_add() succeeds, you should call
device_del() when you want to get rid of it. If device_add() has
not succeeded, use only put_device() to drop the reference
count.
NOTE
_Never_ directly free dev after calling this function, even
if it returned an error! Always use put_device() to give up your
reference instead.
Parameters
struct device *devpointer to the device structure
Description
This happens in two clean steps - initialize the device and add it to the system. The two steps can be called separately, but this is the easiest and most common. I.e. you should only call the two helpers separately if have a clearly defined need to use and refcount the device before it is added to the hierarchy.
For more information, see the kerneldoc for device_initialize()
and device_add().
NOTE
_Never_ directly free dev after calling this function, even
if it returned an error! Always use put_device() to give up the
reference initialized in this function instead.
Parameters
struct device *devdevice.
Description
This simply forwards the call to kobject_get(), though
we do take care to provide for the case that we get a NULL
pointer passed in.
Parameters
struct device *devdevice in question.
Parameters
struct device *devdevice.
Description
This is the first part of the device unregistration
sequence. This removes the device from the lists we control
from here, has it removed from the other driver model
subsystems it was added to in device_add(), and removes it
from the kobject hierarchy.
NOTE
this should be called manually _iff_ device_add() was
also called manually.
Parameters
struct device *devdevice going away.
Description
We do this in two parts, like we do device_register(). First,
we remove it from all the subsystems with device_del(), then
we decrement the reference count via put_device(). If that
is the final reference count, the device will be cleaned up
via device_release() above. Otherwise, the structure will
stick around until the final reference to the device is dropped.
-
int device_for_each_child(struct device *parent, void *data, int (*fn)(struct device *dev, void *data))¶
device child iterator.
Parameters
struct device *parentparent
struct device.void *datadata for the callback.
int (*fn)(struct device *dev, void *data)function to be called for each device.
Description
Iterate over parent’s child devices, and call fn for each, passing it data.
We check the return of fn each time. If it returns anything other than 0, we break out and return that value.
-
int device_for_each_child_reverse(struct device *parent, void *data, int (*fn)(struct device *dev, void *data))¶
device child iterator in reversed order.
Parameters
struct device *parentparent
struct device.void *datadata for the callback.
int (*fn)(struct device *dev, void *data)function to be called for each device.
Description
Iterate over parent’s child devices, and call fn for each, passing it data.
We check the return of fn each time. If it returns anything other than 0, we break out and return that value.
-
struct device *device_find_child(struct device *parent, void *data, int (*match)(struct device *dev, void *data))¶
device iterator for locating a particular device.
Parameters
struct device *parentparent
struct devicevoid *dataData to pass to match function
int (*match)(struct device *dev, void *data)Callback function to check device
Description
This is similar to the device_for_each_child() function above, but it
returns a reference to a device that is ‘found’ for later use, as
determined by the match callback.
The callback should return 0 if the device doesn’t match and non-zero if it does. If the callback returns non-zero and a reference to the current device can be obtained, this function will return to the caller and not iterate over any more devices.
NOTE
you will need to drop the reference with put_device() after use.
-
struct device *device_find_child_by_name(struct device *parent, const char *name)¶
device iterator for locating a child device.
Parameters
struct device *parentparent
struct deviceconst char *namename of the child device
Description
This is similar to the device_find_child() function above, but it
returns a reference to a device that has the name name.
NOTE
you will need to drop the reference with put_device() after use.
-
struct device *device_find_any_child(struct device *parent)¶
device iterator for locating a child device, if any.
Parameters
struct device *parentparent
struct device
Description
This is similar to the device_find_child() function above, but it
returns a reference to a child device, if any.
NOTE
you will need to drop the reference with put_device() after use.
-
struct device *__root_device_register(const char *name, struct module *owner)¶
allocate and register a root device
Parameters
const char *nameroot device name
struct module *ownerowner module of the root device, usually THIS_MODULE
Description
This function allocates a root device and registers it
using device_register(). In order to free the returned
device, use root_device_unregister().
Root devices are dummy devices which allow other devices to be grouped under /sys/devices. Use this function to allocate a root device and then use it as the parent of any device which should appear under /sys/devices/{name}
The /sys/devices/{name} directory will also contain a ‘module’ symlink which points to the owner directory in sysfs.
Returns struct device pointer on success, or ERR_PTR() on error.
Note
You probably want to use root_device_register().
Parameters
struct device *devdevice going away
Description
This function unregisters and cleans up a device that was created by root_device_register().
-
struct device *device_create(const struct class *class, struct device *parent, dev_t devt, void *drvdata, const char *fmt, ...)¶
creates a device and registers it with sysfs
Parameters
const struct class *classpointer to the
struct classthat this device should be registered tostruct device *parentpointer to the parent
struct deviceof this new device, if anydev_t devtthe dev_t for the char device to be added
void *drvdatathe data to be added to the device for callbacks
const char *fmtstring for the device’s name
...variable arguments
Description
This function can be used by char device classes. A struct device
will be created in sysfs, registered to the specified class.
A “dev” file will be created, showing the dev_t for the device, if
the dev_t is not 0,0.
If a pointer to a parent struct device is passed in, the newly created
struct device will be a child of that device in sysfs.
The pointer to the struct device will be returned from the call.
Any further sysfs files that might be required can be created using this
pointer.
Returns struct device pointer on success, or ERR_PTR() on error.
-
struct device *device_create_with_groups(const struct class *class, struct device *parent, dev_t devt, void *drvdata, const struct attribute_group **groups, const char *fmt, ...)¶
creates a device and registers it with sysfs
Parameters
const struct class *classpointer to the
struct classthat this device should be registered tostruct device *parentpointer to the parent
struct deviceof this new device, if anydev_t devtthe dev_t for the char device to be added
void *drvdatathe data to be added to the device for callbacks
const struct attribute_group **groupsNULL-terminated list of attribute groups to be created
const char *fmtstring for the device’s name
...variable arguments
Description
This function can be used by char device classes. A struct device
will be created in sysfs, registered to the specified class.
Additional attributes specified in the groups parameter will also
be created automatically.
A “dev” file will be created, showing the dev_t for the device, if
the dev_t is not 0,0.
If a pointer to a parent struct device is passed in, the newly created
struct device will be a child of that device in sysfs.
The pointer to the struct device will be returned from the call.
Any further sysfs files that might be required can be created using this
pointer.
Returns struct device pointer on success, or ERR_PTR() on error.
-
void device_destroy(const struct class *class, dev_t devt)¶
removes a device that was created with
device_create()
Parameters
const struct class *classpointer to the
struct classthat this device was registered withdev_t devtthe dev_t of the device that was previously registered
Description
This call unregisters and cleans up a device that was created with a
call to device_create().
Parameters
struct device *devthe pointer to the
struct deviceto be renamedconst char *new_namethe new name of the device
Description
It is the responsibility of the caller to provide mutual exclusion between two different calls of device_rename on the same device to ensure that new_name is valid and won’t conflict with other devices.
However, if you’re writing new code, do not call this function. The following text from Kay Sievers offers some insight:
Renaming devices is racy at many levels, symlinks and other stuff are not replaced atomically, and you get a “move” uevent, but it’s not easy to connect the event to the old and new device. Device nodes are not renamed at all, there isn’t even support for that in the kernel now.
In the meantime, during renaming, your target name might be taken by another driver, creating conflicts. Or the old name is taken directly after you renamed it -- then you get events for the same DEVPATH, before you even see the “move” event. It’s just a mess, and nothing new should ever rely on kernel device renaming. Besides that, it’s not even implemented now for other things than (driver-core wise very simple) network devices.
Make up a “real” name in the driver before you register anything, or add some other attributes for userspace to find the device, or use udev to add symlinks -- but never rename kernel devices later, it’s a complete mess. We don’t even want to get into that and try to implement the missing pieces in the core. We really have other pieces to fix in the driver core mess. :)
Note
given that some subsystems (networking and infiniband) use this function, with no immediate plans for this to change, we cannot assume or require that this function not be called at all.
-
int device_move(struct device *dev, struct device *new_parent, enum dpm_order dpm_order)¶
moves a device to a new parent
Parameters
struct device *devthe pointer to the
struct deviceto be movedstruct device *new_parentthe new parent of the device (can be NULL)
enum dpm_order dpm_orderhow to reorder the dpm_list
-
int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)¶
change the owner of an existing device.
Parameters
struct device *devdevice.
kuid_t kuidnew owner’s kuid
kgid_t kgidnew owner’s kgid
Description
This changes the owner of dev and its corresponding sysfs entries to kuid/kgid. This function closely mirrors how dev was added via driver core.
Returns 0 on success or error code on failure.
-
int dev_err_probe(const struct device *dev, int err, const char *fmt, ...)¶
probe error check and log helper
Parameters
const struct device *devthe pointer to the
struct deviceint errerror value to test
const char *fmtprintf-style format string
...arguments as specified in the format string
Description
This helper implements common pattern present in probe functions for error checking: print debug or error message depending if the error value is -EPROBE_DEFER and propagate error upwards. In case of -EPROBE_DEFER it sets also defer probe reason, which can be checked later by reading devices_deferred debugfs attribute. It replaces code sequence:
if (err != -EPROBE_DEFER)
dev_err(dev, ...);
else
dev_dbg(dev, ...);
return err;
with:
return dev_err_probe(dev, err, ...);
Using this helper in your probe function is totally fine even if err is known to never be -EPROBE_DEFER. The benefit compared to a normal dev_err() is the standardized format of the error code, it being emitted symbolically (i.e. you get “EAGAIN” instead of “-35”) and the fact that the error code is returned which allows more compact error paths.
Returns err.
-
void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)¶
Change the primary firmware node of a given device.
Parameters
struct device *devDevice to handle.
struct fwnode_handle *fwnodeNew primary firmware node of the device.
Description
Set the device’s firmware node pointer to fwnode, but if a secondary firmware node of the device is present, preserve it.
- Valid fwnode cases are:
primary --> secondary --> -ENODEV
primary --> NULL
secondary --> -ENODEV
NULL
-
void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode)¶
Change the secondary firmware node of a given device.
Parameters
struct device *devDevice to handle.
struct fwnode_handle *fwnodeNew secondary firmware node of the device.
Description
If a primary firmware node of the device is present, set its secondary pointer to fwnode. Otherwise, set the device’s firmware node pointer to fwnode.
-
void device_set_of_node_from_dev(struct device *dev, const struct device *dev2)¶
reuse device-tree node of another device
Parameters
struct device *devdevice whose device-tree node is being set
const struct device *dev2device whose device-tree node is being reused
Description
Takes another reference to the new device-tree node after first dropping any reference held to the old node.
-
void register_syscore_ops(struct syscore_ops *ops)¶
Register a set of system core operations.
Parameters
struct syscore_ops *opsSystem core operations to register.
-
void unregister_syscore_ops(struct syscore_ops *ops)¶
Unregister a set of system core operations.
Parameters
struct syscore_ops *opsSystem core operations to unregister.
-
int syscore_suspend(void)¶
Execute all the registered system core suspend callbacks.
Parameters
voidno arguments
Description
This function is executed with one CPU on-line and disabled interrupts.
-
void syscore_resume(void)¶
Execute all the registered system core resume callbacks.
Parameters
voidno arguments
Description
This function is executed with one CPU on-line and disabled interrupts.
-
struct device *class_find_device_by_name(const struct class *class, const char *name)¶
device iterator for locating a particular device of a specific name.
Parameters
const struct class *classclass type
const char *namename of the device to match
-
struct device *class_find_device_by_of_node(const struct class *class, const struct device_node *np)¶
device iterator for locating a particular device matching the of_node.
Parameters
const struct class *classclass type
const struct device_node *npof_node of the device to match.
-
struct device *class_find_device_by_fwnode(const struct class *class, const struct fwnode_handle *fwnode)¶
device iterator for locating a particular device matching the fwnode.
Parameters
const struct class *classclass type
const struct fwnode_handle *fwnodefwnode of the device to match.
-
struct device *class_find_device_by_devt(const struct class *class, dev_t devt)¶
device iterator for locating a particular device matching the device type.
Parameters
const struct class *classclass type
dev_t devtdevice type of the device to match.
-
struct device *class_find_device_by_acpi_dev(const struct class *class, const struct acpi_device *adev)¶
device iterator for locating a particular device matching the ACPI_COMPANION device.
Parameters
const struct class *classclass type
const struct acpi_device *adevACPI_COMPANION device to match.
-
struct class *class_create(const char *name)¶
create a
struct classstructure
Parameters
const char *namepointer to a string for the name of this class.
Description
This is used to create a struct class pointer that can then be used
in calls to device_create().
Returns struct class pointer on success, or ERR_PTR() on error.
Note, the pointer created here is to be destroyed when finished by
making a call to class_destroy().
-
void class_destroy(const struct class *cls)¶
destroys a
struct classstructure
Parameters
const struct class *clspointer to the
struct classthat is to be destroyed
Description
Note, the pointer to be destroyed must have been created with a call
to class_create().
-
void class_dev_iter_init(struct class_dev_iter *iter, const struct class *class, const struct device *start, const struct device_type *type)¶
initialize class device iterator
Parameters
struct class_dev_iter *iterclass iterator to initialize
const struct class *classthe class we wanna iterate over
const struct device *startthe device to start iterating from, if any
const struct device_type *typedevice_type of the devices to iterate over, NULL for all
Description
Initialize class iterator iter such that it iterates over devices of class. If start is set, the list iteration will start there, otherwise if it is NULL, the iteration starts at the beginning of the list.
Parameters
struct class_dev_iter *iterclass iterator to proceed
Description
Proceed iter to the next device and return it. Returns NULL if iteration is complete.
The returned device is referenced and won’t be released till iterator is proceed to the next device or exited. The caller is free to do whatever it wants to do with the device including calling back into class code.
-
void class_dev_iter_exit(struct class_dev_iter *iter)¶
finish iteration
Parameters
struct class_dev_iter *iterclass iterator to finish
Description
Finish an iteration. Always call this function after iteration is complete whether the iteration ran till the end or not.
-
int class_for_each_device(const struct class *class, const struct device *start, void *data, int (*fn)(struct device*, void*))¶
device iterator
Parameters
const struct class *classthe class we’re iterating
const struct device *startthe device to start with in the list, if any.
void *datadata for the callback
int (*fn)(struct device *, void *)function to be called for each device
Description
Iterate over class’s list of devices, and call fn for each, passing it data. If start is set, the list iteration will start there, otherwise if it is NULL, the iteration starts at the beginning of the list.
We check the return of fn each time. If it returns anything other than 0, we break out and return that value.
fn is allowed to do anything including calling back into class code. There’s no locking restriction.
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struct device *class_find_device(const struct class *class, const struct device *start, const void *data, int (*match)(struct device*, const void*))¶
device iterator for locating a particular device
Parameters
const struct class *classthe class we’re iterating
const struct device *startDevice to begin with
const void *datadata for the match function
int (*match)(struct device *, const void *)function to check device
Description
This is similar to the class_for_each_dev() function above, but it returns a reference to a device that is ‘found’ for later use, as determined by the match callback.
The callback should return 0 if the device doesn’t match and non-zero if it does. If the callback returns non-zero, this function will return to the caller and not iterate over any more devices.
Note, you will need to drop the reference with put_device() after use.
match is allowed to do anything including calling back into class code. There’s no locking restriction.
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struct class_compat *class_compat_register(const char *name)¶
register a compatibility class
Parameters
const char *namethe name of the class
Description
Compatibility class are meant as a temporary user-space compatibility workaround when converting a family of class devices to a bus devices.
-
void class_compat_unregister(struct class_compat *cls)¶
unregister a compatibility class
Parameters
struct class_compat *clsthe class to unregister
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int class_compat_create_link(struct class_compat *cls, struct device *dev, struct device *device_link)¶
create a compatibility class device link to a bus device
Parameters
struct class_compat *clsthe compatibility class
struct device *devthe target bus device
struct device *device_linkan optional device to which a “device” link should be created
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void class_compat_remove_link(struct class_compat *cls, struct device *dev, struct device *device_link)¶
remove a compatibility class device link to a bus device
Parameters
struct class_compat *clsthe compatibility class
struct device *devthe target bus device
struct device *device_linkan optional device to which a “device” link was previously created
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bool class_is_registered(const struct class *class)¶
determine if at this moment in time, a class is registered in the driver core or not.
Parameters
const struct class *classthe class to check
Description
Returns a boolean to state if the class is registered in the driver core or not. Note that the value could switch right after this call is made, so only use this in places where you “know” it is safe to do so (usually to determine if the specific class has been registered yet or not).
Be careful in using this.
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struct node_access_nodes¶
Access class device to hold user visible relationships to other nodes.
Definition:
struct node_access_nodes {
struct device dev;
struct list_head list_node;
unsigned int access;
#ifdef CONFIG_HMEM_REPORTING;
struct access_coordinate coord;
#endif;
};
Members
devDevice for this memory access class
list_nodeList element in the node’s access list
accessThe access class rank
coordHeterogeneous memory performance coordinates
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struct node_cache_info¶
Internal tracking for memory node caches
Definition:
struct node_cache_info {
struct device dev;
struct list_head node;
struct node_cache_attrs cache_attrs;
};
Members
devDevice represeting the cache level
nodeList element for tracking in the node
cache_attrsAttributes for this cache level
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void node_add_cache(unsigned int nid, struct node_cache_attrs *cache_attrs)¶
add cache attribute to a memory node
Parameters
unsigned int nidNode identifier that has new cache attributes
struct node_cache_attrs *cache_attrsAttributes for the cache being added
Parameters
struct node *nodenode going away
Description
Unregisters a node device node. All the devices on the node must be unregistered before calling this function.
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int register_memory_node_under_compute_node(unsigned int mem_nid, unsigned int cpu_nid, enum access_coordinate_class access)¶
link memory node to its compute node for a given access class.
Parameters
unsigned int mem_nidMemory node number
unsigned int cpu_nidCpu node number
enum access_coordinate_class accessAccess class to register
Description
For use with platforms that may have separate memory and compute nodes. This function will export node relationships linking which memory initiator nodes can access memory targets at a given ranked access class.
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int transport_class_register(struct transport_class *tclass)¶
register an initial transport class
Parameters
struct transport_class *tclassa pointer to the transport class structure to be initialised
Description
The transport class contains an embedded class which is used to identify it. The caller should initialise this structure with zeros and then generic class must have been initialised with the actual transport class unique name. There’s a macro DECLARE_TRANSPORT_CLASS() to do this (declared classes still must be registered).
Returns 0 on success or error on failure.
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void transport_class_unregister(struct transport_class *tclass)¶
unregister a previously registered class
Parameters
struct transport_class *tclassThe transport class to unregister
Description
Must be called prior to deallocating the memory for the transport class.
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int anon_transport_class_register(struct anon_transport_class *atc)¶
register an anonymous class
Parameters
struct anon_transport_class *atcThe anon transport class to register
Description
The anonymous transport class contains both a transport class and a container. The idea of an anonymous class is that it never actually has any device attributes associated with it (and thus saves on container storage). So it can only be used for triggering events. Use prezero and then use DECLARE_ANON_TRANSPORT_CLASS() to initialise the anon transport class storage.
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void anon_transport_class_unregister(struct anon_transport_class *atc)¶
unregister an anon class
Parameters
struct anon_transport_class *atcPointer to the anon transport class to unregister
Description
Must be called prior to deallocating the memory for the anon transport class.
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void transport_setup_device(struct device *dev)¶
declare a new dev for transport class association but don’t make it visible yet.
Parameters
struct device *devthe generic device representing the entity being added
Description
Usually, dev represents some component in the HBA system (either the HBA itself or a device remote across the HBA bus). This routine is simply a trigger point to see if any set of transport classes wishes to associate with the added device. This allocates storage for the class device and initialises it, but does not yet add it to the system or add attributes to it (you do this with transport_add_device). If you have no need for a separate setup and add operations, use transport_register_device (see transport_class.h).
Parameters
struct device *devthe generic device representing the entity being added
Description
Usually, dev represents some component in the HBA system (either the HBA itself or a device remote across the HBA bus). This routine is simply a trigger point used to add the device to the system and register attributes for it.
Parameters
struct device *devgeneric device representing device to be configured
Description
The idea of configure is simply to provide a point within the setup process to allow the transport class to extract information from a device after it has been setup. This is used in SCSI because we have to have a setup device to begin using the HBA, but after we send the initial inquiry, we use configure to extract the device parameters. The device need not have been added to be configured.
Parameters
struct device *devgeneric device to remove
Description
This call removes the visibility of the device (to the user from sysfs), but does not destroy it. To eliminate a device entirely you must also call transport_destroy_device. If you don’t need to do remove and destroy as separate operations, use transport_unregister_device() (see transport_class.h) which will perform both calls for you.
Parameters
struct device *devdevice to eliminate from the transport class.
Description
This call triggers the elimination of storage associated with the transport classdev. Note: all it really does is relinquish a reference to the classdev. The memory will not be freed until the last reference goes to zero. Note also that the classdev retains a reference count on dev, so dev too will remain for as long as the transport class device remains around.
Parameters
struct device *devdevice to check
Return
-ENODEV if initcalls have completed and modules are disabled.
-ETIMEDOUT if the deferred probe timeout was set and has expired and modules are enabled.
-EPROBE_DEFER in other cases.
Description
Drivers or subsystems can opt-in to calling this function instead of directly returning -EPROBE_DEFER.
Parameters
struct device *devdevice.
Description
Allow manual attachment of a driver to a device. Caller must have already set dev->driver.
Note that this does not modify the bus reference count. Please verify that is accounted for before calling this. (It is ok to call with no other effort from a driver’s probe() method.)
This function must be called with the device lock held.
Callers should prefer to use device_driver_attach() instead.
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void wait_for_device_probe(void)¶
Parameters
voidno arguments
Description
Wait for device probing to be completed.
Parameters
struct device *devdevice.
Description
Walk the list of drivers that the bus has and call driver_probe_device() for each pair. If a compatible pair is found, break out and return.
Returns 1 if the device was bound to a driver; 0 if no matching driver was found; -ENODEV if the device is not registered.
When called for a USB interface, dev->parent lock must be held.
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int device_driver_attach(struct device_driver *drv, struct device *dev)¶
attach a specific driver to a specific device
Parameters
struct device_driver *drvDriver to attach
struct device *devDevice to attach it to
Description
Manually attach driver to a device. Will acquire both dev lock and dev->parent lock if needed. Returns 0 on success, -ERR on failure.
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int driver_attach(struct device_driver *drv)¶
try to bind driver to devices.
Parameters
struct device_driver *drvdriver.
Description
Walk the list of devices that the bus has on it and try to match the driver with each one. If driver_probe_device() returns 0 and the dev->driver is set, we’ve found a compatible pair.
Parameters
struct device *devdevice.
Description
Manually detach device from driver. When called for a USB interface, dev->parent lock must be held.
If this function is to be called with dev->parent lock held, ensure that the device’s consumers are unbound in advance or that their locks can be acquired under the dev->parent lock.
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struct platform_device *platform_device_register_resndata(struct device *parent, const char *name, int id, const struct resource *res, unsigned int num, const void *data, size_t size)¶
add a platform-level device with resources and platform-specific data
Parameters
struct device *parentparent device for the device we’re adding
const char *namebase name of the device we’re adding
int idinstance id
const struct resource *resset of resources that needs to be allocated for the device
unsigned int numnumber of resources
const void *dataplatform specific data for this platform device
size_t sizesize of platform specific data
Description
Returns struct platform_device pointer on success, or ERR_PTR() on error.
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struct platform_device *platform_device_register_simple(const char *name, int id, const struct resource *res, unsigned int num)¶
add a platform-level device and its resources
Parameters
const char *namebase name of the device we’re adding
int idinstance id
const struct resource *resset of resources that needs to be allocated for the device
unsigned int numnumber of resources
Description
This function creates a simple platform device that requires minimal resource and memory management. Canned release function freeing memory allocated for the device allows drivers using such devices to be unloaded without waiting for the last reference to the device to be dropped.
This interface is primarily intended for use with legacy drivers which probe hardware directly. Because such drivers create sysfs device nodes themselves, rather than letting system infrastructure handle such device enumeration tasks, they don’t fully conform to the Linux driver model. In particular, when such drivers are built as modules, they can’t be “hotplugged”.
Returns struct platform_device pointer on success, or ERR_PTR() on error.
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struct platform_device *platform_device_register_data(struct device *parent, const char *name, int id, const void *data, size_t size)¶
add a platform-level device with platform-specific data
Parameters
struct device *parentparent device for the device we’re adding
const char *namebase name of the device we’re adding
int idinstance id
const void *dataplatform specific data for this platform device
size_t sizesize of platform specific data
Description
This function creates a simple platform device that requires minimal resource and memory management. Canned release function freeing memory allocated for the device allows drivers using such devices to be unloaded without waiting for the last reference to the device to be dropped.
Returns struct platform_device pointer on success, or ERR_PTR() on error.
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struct resource *platform_get_resource(struct platform_device *dev, unsigned int type, unsigned int num)¶
get a resource for a device
Parameters
struct platform_device *devplatform device
unsigned int typeresource type
unsigned int numresource index
Return
a pointer to the resource or NULL on failure.
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void __iomem *devm_platform_get_and_ioremap_resource(struct platform_device *pdev, unsigned int index, struct resource **res)¶
call devm_ioremap_resource() for a platform device and get resource
Parameters
struct platform_device *pdevplatform device to use both for memory resource lookup as well as resource management
unsigned int indexresource index
struct resource **resoptional output parameter to store a pointer to the obtained resource.
Return
a pointer to the remapped memory or an ERR_PTR() encoded error code
on failure.
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void __iomem *devm_platform_ioremap_resource(struct platform_device *pdev, unsigned int index)¶
call devm_ioremap_resource() for a platform device
Parameters
struct platform_device *pdevplatform device to use both for memory resource lookup as well as resource management
unsigned int indexresource index
Return
a pointer to the remapped memory or an ERR_PTR() encoded error code
on failure.
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void __iomem *devm_platform_ioremap_resource_byname(struct platform_device *pdev, const char *name)¶
call devm_ioremap_resource for a platform device, retrieve the resource by name
Parameters
struct platform_device *pdevplatform device to use both for memory resource lookup as well as resource management
const char *namename of the resource
Return
a pointer to the remapped memory or an ERR_PTR() encoded error code
on failure.
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int platform_get_irq_optional(struct platform_device *dev, unsigned int num)¶
get an optional IRQ for a device
Parameters
struct platform_device *devplatform device
unsigned int numIRQ number index
Description
Gets an IRQ for a platform device. Device drivers should check the return
value for errors so as to not pass a negative integer value to the
request_irq() APIs. This is the same as platform_get_irq(), except that it
does not print an error message if an IRQ can not be obtained.
For example:
int irq = platform_get_irq_optional(pdev, 0);
if (irq < 0)
return irq;
Return
non-zero IRQ number on success, negative error number on failure.
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int platform_get_irq(struct platform_device *dev, unsigned int num)¶
get an IRQ for a device
Parameters
struct platform_device *devplatform device
unsigned int numIRQ number index
Description
Gets an IRQ for a platform device and prints an error message if finding the
IRQ fails. Device drivers should check the return value for errors so as to
not pass a negative integer value to the request_irq() APIs.
For example:
int irq = platform_get_irq(pdev, 0);
if (irq < 0)
return irq;
Return
non-zero IRQ number on success, negative error number on failure.
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int platform_irq_count(struct platform_device *dev)¶
Count the number of IRQs a platform device uses
Parameters
struct platform_device *devplatform device
Return
Number of IRQs a platform device uses or EPROBE_DEFER
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int devm_platform_get_irqs_affinity(struct platform_device *dev, struct irq_affinity *affd, unsigned int minvec, unsigned int maxvec, int **irqs)¶
devm method to get a set of IRQs for a device using an interrupt affinity descriptor
Parameters
struct platform_device *devplatform device pointer
struct irq_affinity *affdaffinity descriptor
unsigned int minvecminimum count of interrupt vectors
unsigned int maxvecmaximum count of interrupt vectors
int **irqspointer holder for IRQ numbers
Description
Gets a set of IRQs for a platform device, and updates IRQ afffinty according to the passed affinity descriptor
Return
Number of vectors on success, negative error number on failure.
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struct resource *platform_get_resource_byname(struct platform_device *dev, unsigned int type, const char *name)¶
get a resource for a device by name
Parameters
struct platform_device *devplatform device
unsigned int typeresource type
const char *nameresource name
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int platform_get_irq_byname(struct platform_device *dev, const char *name)¶
get an IRQ for a device by name
Parameters
struct platform_device *devplatform device
const char *nameIRQ name
Description
Get an IRQ like platform_get_irq(), but then by name rather then by index.
Return
non-zero IRQ number on success, negative error number on failure.
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int platform_get_irq_byname_optional(struct platform_device *dev, const char *name)¶
get an optional IRQ for a device by name
Parameters
struct platform_device *devplatform device
const char *nameIRQ name
Description
Get an optional IRQ by name like platform_get_irq_byname(). Except that it
does not print an error message if an IRQ can not be obtained.
Return
non-zero IRQ number on success, negative error number on failure.
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int platform_add_devices(struct platform_device **devs, int num)¶
add a numbers of platform devices
Parameters
struct platform_device **devsarray of platform devices to add
int numnumber of platform devices in array
Return
0 on success, negative error number on failure.
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void platform_device_put(struct platform_device *pdev)¶
destroy a platform device
Parameters
struct platform_device *pdevplatform device to free
Description
Free all memory associated with a platform device. This function must _only_ be externally called in error cases. All other usage is a bug.
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struct platform_device *platform_device_alloc(const char *name, int id)¶
create a platform device
Parameters
const char *namebase name of the device we’re adding
int idinstance id
Description
Create a platform device object which can have other objects attached to it, and which will have attached objects freed when it is released.
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int platform_device_add_resources(struct platform_device *pdev, const struct resource *res, unsigned int num)¶
add resources to a platform device
Parameters
struct platform_device *pdevplatform device allocated by platform_device_alloc to add resources to
const struct resource *resset of resources that needs to be allocated for the device
unsigned int numnumber of resources
Description
Add a copy of the resources to the platform device. The memory associated with the resources will be freed when the platform device is released.
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int platform_device_add_data(struct platform_device *pdev, const void *data, size_t size)¶
add platform-specific data to a platform device
Parameters
struct platform_device *pdevplatform device allocated by platform_device_alloc to add resources to
const void *dataplatform specific data for this platform device
size_t sizesize of platform specific data
Description
Add a copy of platform specific data to the platform device’s platform_data pointer. The memory associated with the platform data will be freed when the platform device is released.
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int platform_device_add(struct platform_device *pdev)¶
add a platform device to device hierarchy
Parameters
struct platform_device *pdevplatform device we’re adding
Description
This is part 2 of platform_device_register(), though may be called
separately _iff_ pdev was allocated by platform_device_alloc().
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void platform_device_del(struct platform_device *pdev)¶
remove a platform-level device
Parameters
struct platform_device *pdevplatform device we’re removing
Description
Note that this function will also release all memory- and port-based resources owned by the device (dev->resource). This function must _only_ be externally called in error cases. All other usage is a bug.
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int platform_device_register(struct platform_device *pdev)¶
add a platform-level device
Parameters
struct platform_device *pdevplatform device we’re adding
NOTE
_Never_ directly free pdev after calling this function, even if it
returned an error! Always use platform_device_put() to give up the
reference initialised in this function instead.
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void platform_device_unregister(struct platform_device *pdev)¶
unregister a platform-level device
Parameters
struct platform_device *pdevplatform device we’re unregistering
Description
Unregistration is done in 2 steps. First we release all resources
and remove it from the subsystem, then we drop reference count by
calling platform_device_put().
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struct platform_device *platform_device_register_full(const struct platform_device_info *pdevinfo)¶
add a platform-level device with resources and platform-specific data
Parameters
const struct platform_device_info *pdevinfodata used to create device
Description
Returns struct platform_device pointer on success, or ERR_PTR() on error.
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int __platform_driver_register(struct platform_driver *drv, struct module *owner)¶
register a driver for platform-level devices
Parameters
struct platform_driver *drvplatform driver structure
struct module *ownerowning module/driver
-
void platform_driver_unregister(struct platform_driver *drv)¶
unregister a driver for platform-level devices
Parameters
struct platform_driver *drvplatform driver structure
-
int __platform_driver_probe(struct platform_driver *drv, int (*probe)(struct platform_device*), struct module *module)¶
register driver for non-hotpluggable device
Parameters
struct platform_driver *drvplatform driver structure
int (*probe)(struct platform_device *)the driver probe routine, probably from an __init section
struct module *modulemodule which will be the owner of the driver
Description
Use this instead of platform_driver_register() when you know the device is not hotpluggable and has already been registered, and you want to remove its run-once probe() infrastructure from memory after the driver has bound to the device.
One typical use for this would be with drivers for controllers integrated into system-on-chip processors, where the controller devices have been configured as part of board setup.
Note that this is incompatible with deferred probing.
Returns zero if the driver registered and bound to a device, else returns a negative error code and with the driver not registered.
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struct platform_device *__platform_create_bundle(struct platform_driver *driver, int (*probe)(struct platform_device*), struct resource *res, unsigned int n_res, const void *data, size_t size, struct module *module)¶
register driver and create corresponding device
Parameters
struct platform_driver *driverplatform driver structure
int (*probe)(struct platform_device *)the driver probe routine, probably from an __init section
struct resource *resset of resources that needs to be allocated for the device
unsigned int n_resnumber of resources
const void *dataplatform specific data for this platform device
size_t sizesize of platform specific data
struct module *modulemodule which will be the owner of the driver
Description
Use this in legacy-style modules that probe hardware directly and register a single platform device and corresponding platform driver.
Returns struct platform_device pointer on success, or ERR_PTR() on error.
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int __platform_register_drivers(struct platform_driver *const *drivers, unsigned int count, struct module *owner)¶
register an array of platform drivers
Parameters
struct platform_driver * const *driversan array of drivers to register
unsigned int countthe number of drivers to register
struct module *ownermodule owning the drivers
Description
Registers platform drivers specified by an array. On failure to register a
driver, all previously registered drivers will be unregistered. Callers of
this API should use platform_unregister_drivers() to unregister drivers in
the reverse order.
Return
0 on success or a negative error code on failure.
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void platform_unregister_drivers(struct platform_driver *const *drivers, unsigned int count)¶
unregister an array of platform drivers
Parameters
struct platform_driver * const *driversan array of drivers to unregister
unsigned int countthe number of drivers to unregister
Description
Unregisters platform drivers specified by an array. This is typically used to complement an earlier call to platform_register_drivers(). Drivers are unregistered in the reverse order in which they were registered.
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struct device *platform_find_device_by_driver(struct device *start, const struct device_driver *drv)¶
Find a platform device with a given driver.
Parameters
struct device *startThe device to start the search from.
const struct device_driver *drvThe device driver to look for.
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struct device *bus_find_device_by_name(const struct bus_type *bus, struct device *start, const char *name)¶
device iterator for locating a particular device of a specific name.
Parameters
const struct bus_type *busbus type
struct device *startDevice to begin with
const char *namename of the device to match
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struct device *bus_find_device_by_of_node(const struct bus_type *bus, const struct device_node *np)¶
device iterator for locating a particular device matching the of_node.
Parameters
const struct bus_type *busbus type
const struct device_node *npof_node of the device to match.
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struct device *bus_find_device_by_fwnode(const struct bus_type *bus, const struct fwnode_handle *fwnode)¶
device iterator for locating a particular device matching the fwnode.
Parameters
const struct bus_type *busbus type
const struct fwnode_handle *fwnodefwnode of the device to match.
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struct device *bus_find_device_by_devt(const struct bus_type *bus, dev_t devt)¶
device iterator for locating a particular device matching the device type.
Parameters
const struct bus_type *busbus type
dev_t devtdevice type of the device to match.
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struct device *bus_find_next_device(const struct bus_type *bus, struct device *cur)¶
Find the next device after a given device in a given bus.
Parameters
const struct bus_type *busbus type
struct device *curdevice to begin the search with.
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struct device *bus_find_device_by_acpi_dev(const struct bus_type *bus, const struct acpi_device *adev)¶
device iterator for locating a particular device matching the ACPI COMPANION device.
Parameters
const struct bus_type *busbus type
const struct acpi_device *adevACPI COMPANION device to match.
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int bus_for_each_dev(const struct bus_type *bus, struct device *start, void *data, int (*fn)(struct device*, void*))¶
device iterator.
Parameters
const struct bus_type *busbus type.
struct device *startdevice to start iterating from.
void *datadata for the callback.
int (*fn)(struct device *, void *)function to be called for each device.
Description
Iterate over bus’s list of devices, and call fn for each, passing it data. If start is not NULL, we use that device to begin iterating from.
We check the return of fn each time. If it returns anything other than 0, we break out and return that value.
NOTE
The device that returns a non-zero value is not retained in any way, nor is its refcount incremented. If the caller needs to retain this data, it should do so, and increment the reference count in the supplied callback.
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struct device *bus_find_device(const struct bus_type *bus, struct device *start, const void *data, int (*match)(struct device *dev, const void *data))¶
device iterator for locating a particular device.
Parameters
const struct bus_type *busbus type
struct device *startDevice to begin with
const void *dataData to pass to match function
int (*match)(struct device *dev, const void *data)Callback function to check device
Description
This is similar to the bus_for_each_dev() function above, but it
returns a reference to a device that is ‘found’ for later use, as
determined by the match callback.
The callback should return 0 if the device doesn’t match and non-zero if it does. If the callback returns non-zero, this function will return to the caller and not iterate over any more devices.
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int bus_for_each_drv(const struct bus_type *bus, struct device_driver *start, void *data, int (*fn)(struct device_driver*, void*))¶
driver iterator
Parameters
const struct bus_type *busbus we’re dealing with.
struct device_driver *startdriver to start iterating on.
void *datadata to pass to the callback.
int (*fn)(struct device_driver *, void *)function to call for each driver.
Description
This is nearly identical to the device iterator above. We iterate over each driver that belongs to bus, and call fn for each. If fn returns anything but 0, we break out and return it. If start is not NULL, we use it as the head of the list.
NOTE
we don’t return the driver that returns a non-zero value, nor do we leave the reference count incremented for that driver. If the caller needs to know that info, it must set it in the callback. It must also be sure to increment the refcount so it doesn’t disappear before returning to the caller.
Parameters
const struct bus_type *busthe bus to scan.
Description
This function will look for devices on the bus with no driver
attached and rescan it against existing drivers to see if it matches
any by calling device_attach() for the unbound devices.
Parameters
struct device *devthe device to reprobe
Description
This function detaches the attached driver (if any) for the given device and restarts the driver probing process. It is intended to use if probing criteria changed during a devices lifetime and driver attachment should change accordingly.
Parameters
const struct bus_type *busbus to register
Description
Once we have that, we register the bus with the kobject infrastructure, then register the children subsystems it has: the devices and drivers that belong to the subsystem.
Parameters
const struct bus_type *busbus.
Description
Unregister the child subsystems and the bus itself. Finally, we call bus_put() to release the refcount
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int subsys_system_register(const struct bus_type *subsys, const struct attribute_group **groups)¶
register a subsystem at /sys/devices/system/
Parameters
const struct bus_type *subsyssystem subsystem
const struct attribute_group **groupsdefault attributes for the root device
Description
All ‘system’ subsystems have a /sys/devices/system/<name> root device with the name of the subsystem. The root device can carry subsystem- wide attributes. All registered devices are below this single root device and are named after the subsystem with a simple enumeration number appended. The registered devices are not explicitly named; only ‘id’ in the device needs to be set.
Do not use this interface for anything new, it exists for compatibility with bad ideas only. New subsystems should use plain subsystems; and add the subsystem-wide attributes should be added to the subsystem directory itself and not some create fake root-device placed in /sys/devices/system/<name>.
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int subsys_virtual_register(const struct bus_type *subsys, const struct attribute_group **groups)¶
register a subsystem at /sys/devices/virtual/
Parameters
const struct bus_type *subsysvirtual subsystem
const struct attribute_group **groupsdefault attributes for the root device
Description
All ‘virtual’ subsystems have a /sys/devices/system/<name> root device with the name of the subystem. The root device can carry subsystem-wide attributes. All registered devices are below this single root device. There’s no restriction on device naming. This is for kernel software constructs which need sysfs interface.
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struct device_driver *driver_find(const char *name, const struct bus_type *bus)¶
locate driver on a bus by its name.
Parameters
const char *namename of the driver.
const struct bus_type *busbus to scan for the driver.
Description
Call kset_find_obj() to iterate over list of drivers on
a bus to find driver by name. Return driver if found.
This routine provides no locking to prevent the driver it returns from being unregistered or unloaded while the caller is using it. The caller is responsible for preventing this.
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struct device *bus_get_dev_root(const struct bus_type *bus)¶
return a pointer to the “device root” of a bus
Parameters
const struct bus_type *busbus to return the device root of.
Description
If a bus has a “device root” structure, return it, WITH THE REFERENCE COUNT INCREMENTED.
Note, when finished with the device, a call to put_device() is required.
If the device root is not present (or bus is not a valid pointer), NULL will be returned.
Device Drivers DMA Management¶
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void dmam_free_coherent(struct device *dev, size_t size, void *vaddr, dma_addr_t dma_handle)¶
Managed dma_free_coherent()
Parameters
struct device *devDevice to free coherent memory for
size_t sizeSize of allocation
void *vaddrVirtual address of the memory to free
dma_addr_t dma_handleDMA handle of the memory to free
Description
Managed dma_free_coherent().
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void *dmam_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)¶
Managed dma_alloc_attrs()
Parameters
struct device *devDevice to allocate non_coherent memory for
size_t sizeSize of allocation
dma_addr_t *dma_handleOut argument for allocated DMA handle
gfp_t gfpAllocation flags
unsigned long attrsFlags in the DMA_ATTR_* namespace.
Description
Managed dma_alloc_attrs(). Memory allocated using this function will be automatically released on driver detach.
Return
Pointer to allocated memory on success, NULL on failure.
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unsigned int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir, unsigned long attrs)¶
Map the given buffer for DMA
Parameters
struct device *devThe device for which to perform the DMA operation
struct scatterlist *sgThe sg_table object describing the buffer
int nentsNumber of entries to map
enum dma_data_direction dirDMA direction
unsigned long attrsOptional DMA attributes for the map operation
Description
Maps a buffer described by a scatterlist passed in the sg argument with nents segments for the dir DMA operation by the dev device.
Returns the number of mapped entries (which can be less than nents) on success. Zero is returned for any error.
dma_unmap_sg_attrs() should be used to unmap the buffer with the original sg and original nents (not the value returned by this funciton).
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int dma_map_sgtable(struct device *dev, struct sg_table *sgt, enum dma_data_direction dir, unsigned long attrs)¶
Map the given buffer for DMA
Parameters
struct device *devThe device for which to perform the DMA operation
struct sg_table *sgtThe sg_table object describing the buffer
enum dma_data_direction dirDMA direction
unsigned long attrsOptional DMA attributes for the map operation
Description
Maps a buffer described by a scatterlist stored in the given sg_table object for the dir DMA operation by the dev device. After success, the ownership for the buffer is transferred to the DMA domain. One has to call dma_sync_sgtable_for_cpu() or dma_unmap_sgtable() to move the ownership of the buffer back to the CPU domain before touching the buffer by the CPU.
Returns 0 on success or a negative error code on error. The following error codes are supported with the given meaning:
- -EINVAL
An invalid argument, unaligned access or other error in usage. Will not succeed if retried.
- -ENOMEM
Insufficient resources (like memory or IOVA space) to complete the mapping. Should succeed if retried later.
- -EIO
Legacy error code with an unknown meaning. eg. this is returned if a lower level call returned DMA_MAPPING_ERROR.
- -EREMOTEIO
The DMA device cannot access P2PDMA memory specified in the sg_table. This will not succeed if retried.
Parameters
struct device *devdevice to check
Description
Returns true if dev supports dma_mmap_coherent() and dma_mmap_attrs() to
map DMA allocations to userspace.
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int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma, void *cpu_addr, dma_addr_t dma_addr, size_t size, unsigned long attrs)¶
map a coherent DMA allocation into user space
Parameters
struct device *devvalid
struct devicepointer, or NULL for ISA and EISA-like devicesstruct vm_area_struct *vmavm_area_struct describing requested user mapping
void *cpu_addrkernel CPU-view address returned from dma_alloc_attrs
dma_addr_t dma_addrdevice-view address returned from dma_alloc_attrs
size_t sizesize of memory originally requested in dma_alloc_attrs
unsigned long attrsattributes of mapping properties requested in dma_alloc_attrs
Description
Map a coherent DMA buffer previously allocated by dma_alloc_attrs into user space. The coherent DMA buffer must not be freed by the driver until the user space mapping has been released.
Parameters
struct device *devdevice to check
Description
Return true if the devices DMA mask is too small to address all memory in
the system, else false. Lack of addressing bits is the prime reason for
bounce buffering, but might not be the only one.
Device drivers PnP support¶
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int pnp_register_protocol(struct pnp_protocol *protocol)¶
adds a pnp protocol to the pnp layer
Parameters
struct pnp_protocol *protocolpointer to the corresponding pnp_protocol structure
Ex protocols: ISAPNP, PNPBIOS, etc
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void pnp_unregister_protocol(struct pnp_protocol *protocol)¶
removes a pnp protocol from the pnp layer
Parameters
struct pnp_protocol *protocolpointer to the corresponding pnp_protocol structure
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struct pnp_dev *pnp_request_card_device(struct pnp_card_link *clink, const char *id, struct pnp_dev *from)¶
Searches for a PnP device under the specified card
Parameters
struct pnp_card_link *clinkpointer to the card link, cannot be NULL
const char *idpointer to a PnP ID structure that explains the rules for finding the device
struct pnp_dev *fromStarting place to search from. If NULL it will start from the beginning.
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void pnp_release_card_device(struct pnp_dev *dev)¶
call this when the driver no longer needs the device
Parameters
struct pnp_dev *devpointer to the PnP device structure
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int pnp_register_card_driver(struct pnp_card_driver *drv)¶
registers a PnP card driver with the PnP Layer
Parameters
struct pnp_card_driver *drvpointer to the driver to register
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void pnp_unregister_card_driver(struct pnp_card_driver *drv)¶
unregisters a PnP card driver from the PnP Layer
Parameters
struct pnp_card_driver *drvpointer to the driver to unregister
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struct pnp_id *pnp_add_id(struct pnp_dev *dev, const char *id)¶
adds an EISA id to the specified device
Parameters
struct pnp_dev *devpointer to the desired device
const char *idpointer to an EISA id string
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int pnp_start_dev(struct pnp_dev *dev)¶
low-level start of the PnP device
Parameters
struct pnp_dev *devpointer to the desired device
Description
assumes that resources have already been allocated
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int pnp_stop_dev(struct pnp_dev *dev)¶
low-level disable of the PnP device
Parameters
struct pnp_dev *devpointer to the desired device
Description
does not free resources
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int pnp_activate_dev(struct pnp_dev *dev)¶
activates a PnP device for use
Parameters
struct pnp_dev *devpointer to the desired device
Description
does not validate or set resources so be careful.
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int pnp_disable_dev(struct pnp_dev *dev)¶
disables device
Parameters
struct pnp_dev *devpointer to the desired device
Description
inform the correct pnp protocol so that resources can be used by other devices
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int pnp_is_active(struct pnp_dev *dev)¶
Determines if a device is active based on its current resources
Parameters
struct pnp_dev *devpointer to the desired PnP device
Userspace IO devices¶
Parameters
struct uio_info *infoUIO device capabilities
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int __uio_register_device(struct module *owner, struct device *parent, struct uio_info *info)¶
register a new userspace IO device
Parameters
struct module *ownermodule that creates the new device
struct device *parentparent device
struct uio_info *infoUIO device capabilities
Description
returns zero on success or a negative error code.
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int __devm_uio_register_device(struct module *owner, struct device *parent, struct uio_info *info)¶
Resource managed
uio_register_device()
Parameters
struct module *ownermodule that creates the new device
struct device *parentparent device
struct uio_info *infoUIO device capabilities
Description
returns zero on success or a negative error code.
Parameters
struct uio_info *infoUIO device capabilities
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struct uio_mem¶
description of a UIO memory region
Definition:
struct uio_mem {
const char *name;
phys_addr_t addr;
dma_addr_t dma_addr;
unsigned long offs;
resource_size_t size;
int memtype;
void __iomem *internal_addr;
struct device *dma_device;
struct uio_map *map;
};
Members
namename of the memory region for identification
addraddress of the device’s memory rounded to page size (phys_addr is used since addr can be logical, virtual, or physical & phys_addr_t should always be large enough to handle any of the address types)
dma_addrDMA handle set by dma_alloc_coherent, used with UIO_MEM_DMA_COHERENT only (addr should be the void * returned from the same dma_alloc_coherent call)
offsoffset of device memory within the page
sizesize of IO (multiple of page size)
memtypetype of memory addr points to
internal_addrioremap-ped version of addr, for driver internal use
dma_devicedevice struct that was passed to dma_alloc_coherent, used with UIO_MEM_DMA_COHERENT only
mapfor use by the UIO core only.
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struct uio_port¶
description of a UIO port region
Definition:
struct uio_port {
const char *name;
unsigned long start;
unsigned long size;
int porttype;
struct uio_portio *portio;
};
Members
namename of the port region for identification
startstart of port region
sizesize of port region
porttypetype of port (see UIO_PORT_* below)
portiofor use by the UIO core only.
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struct uio_info¶
UIO device capabilities
Definition:
struct uio_info {
struct uio_device *uio_dev;
const char *name;
const char *version;
struct uio_mem mem[MAX_UIO_MAPS];
struct uio_port port[MAX_UIO_PORT_REGIONS];
long irq;
unsigned long irq_flags;
void *priv;
irqreturn_t (*handler)(int irq, struct uio_info *dev_info);
int (*mmap)(struct uio_info *info, struct vm_area_struct *vma);
int (*open)(struct uio_info *info, struct inode *inode);
int (*release)(struct uio_info *info, struct inode *inode);
int (*irqcontrol)(struct uio_info *info, s32 irq_on);
};
Members
uio_devthe UIO device this info belongs to
namedevice name
versiondevice driver version
memlist of mappable memory regions, size==0 for end of list
portlist of port regions, size==0 for end of list
irqinterrupt number or UIO_IRQ_CUSTOM
irq_flagsflags for
request_irq()privoptional private data
handlerthe device’s irq handler
mmapmmap operation for this uio device
openopen operation for this uio device
releaserelease operation for this uio device
irqcontroldisable/enable irqs when 0/1 is written to /dev/uioX
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uio_register_device¶
uio_register_device (parent, info)
register a new userspace IO device
Parameters
parentparent device
infoUIO device capabilities
Description
returns zero on success or a negative error code.
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devm_uio_register_device¶
devm_uio_register_device (parent, info)
Resource managed
uio_register_device()
Parameters
parentparent device
infoUIO device capabilities
Description
returns zero on success or a negative error code.