WMI Driver API¶

The WMI driver core supports a more modern bus-based interface for interacting with WMI devices, and an older GUID-based interface. The latter interface is considered to be deprecated, so new WMI drivers should generally avoid it since it has some issues with multiple WMI devices and events sharing the same GUIDs and/or notification IDs. The modern bus-based interface instead maps each WMI device to a struct wmi_device, so it supports WMI devices sharing GUIDs and/or notification IDs. Drivers can then register a struct wmi_driver, which will be bound to compatible WMI devices by the driver core.

struct wmi_device¶: WMI device structure

Definition:

struct wmi_device {
    struct device dev;
};

Members

dev: Device associated with this WMI device

Description

This represents WMI devices discovered by the WMI driver core.

struct wmi_driver¶: WMI driver structure

Definition:

struct wmi_driver {
    struct device_driver driver;
    const struct wmi_device_id *id_table;
    bool no_notify_data;
    int (*probe)(struct wmi_device *wdev, const void *context);
    void (*remove)(struct wmi_device *wdev);
    void (*notify)(struct wmi_device *device, union acpi_object *data);
    long (*filter_callback)(struct wmi_device *wdev, unsigned int cmd, struct wmi_ioctl_buffer *arg);
};

Members

driver: Driver model structure
id_table: List of WMI GUIDs supported by this driver
no_notify_data: WMI events provide no event data
probe: Callback for device binding
remove: Callback for device unbinding
notify: Callback for receiving WMI events
filter_callback: Callback for filtering device IOCTLs

Description

This represents WMI drivers which handle WMI devices. filter_callback is only necessary for drivers which want to set up a WMI IOCTL interface.

wmi_driver_register¶

wmi_driver_register (driver)

Helper macro to register a WMI driver

Parameters

driver: wmi_driver struct

Description

Helper macro for registering a WMI driver. It automatically passes THIS_MODULE to the underlying function.

module_wmi_driver¶

module_wmi_driver (__wmi_driver)

Helper macro to register/unregister a WMI driver

Parameters

__wmi_driver: wmi_driver struct

Description

Helper macro for WMI drivers which do not 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() and module_exit().

int set_required_buffer_size(struct wmi_device *wdev, u64 length)¶: Sets the buffer size needed for performing IOCTL

Parameters

struct wmi_device *wdev: A wmi bus device from a driver
u64 length: Required buffer size

Description

Allocates memory needed for buffer, stores the buffer size in that memory.

Return

0 on success or a negative error code for failure.

int wmi_instance_count(const char *guid_string)¶: Get number of WMI object instances

Parameters

const char *guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba

Description

Get the number of WMI object instances.

Return

Number of WMI object instances or negative error code.

u8 wmidev_instance_count(struct wmi_device *wdev)¶: Get number of WMI object instances

Parameters

struct wmi_device *wdev: A wmi bus device from a driver

Description

Get the number of WMI object instances.

Return

Number of WMI object instances.

acpi_status wmi_evaluate_method(const char *guid_string, u8 instance, u32 method_id, const struct acpi_buffer *in, struct acpi_buffer *out)¶: Evaluate a WMI method (deprecated)

Parameters

const char *guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
u8 instance: Instance index
u32 method_id: Method ID to call
const struct acpi_buffer *in: Buffer containing input for the method call
struct acpi_buffer *out: Empty buffer to return the method results

Description

Call an ACPI-WMI method, the caller must free out.

Return

acpi_status signaling success or error.

acpi_status wmidev_evaluate_method(struct wmi_device *wdev, u8 instance, u32 method_id, const struct acpi_buffer *in, struct acpi_buffer *out)¶: Evaluate a WMI method

Parameters

struct wmi_device *wdev: A wmi bus device from a driver
u8 instance: Instance index
u32 method_id: Method ID to call
const struct acpi_buffer *in: Buffer containing input for the method call
struct acpi_buffer *out: Empty buffer to return the method results

Description

Call an ACPI-WMI method, the caller must free out.

Return

acpi_status signaling success or error.

acpi_status wmi_query_block(const char *guid_string, u8 instance, struct acpi_buffer *out)¶: Return contents of a WMI block (deprecated)

Parameters

const char *guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
u8 instance: Instance index
struct acpi_buffer *out: Empty buffer to return the contents of the data block to

Description

Query a ACPI-WMI block, the caller must free out.

Return

ACPI object containing the content of the WMI block.

union acpi_object *wmidev_block_query(struct wmi_device *wdev, u8 instance)¶: Return contents of a WMI block

Parameters

struct wmi_device *wdev: A wmi bus device from a driver
u8 instance: Instance index

Description

Query an ACPI-WMI block, the caller must free the result.

Return

ACPI object containing the content of the WMI block.

acpi_status wmi_set_block(const char *guid_string, u8 instance, const struct acpi_buffer *in)¶: Write to a WMI block (deprecated)

Parameters

const char *guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
u8 instance: Instance index
const struct acpi_buffer *in: Buffer containing new values for the data block

Description

Write the contents of the input buffer to an ACPI-WMI data block.

Return

acpi_status signaling success or error.

acpi_status wmi_install_notify_handler(const char *guid, wmi_notify_handler handler, void *data)¶: Register handler for WMI events (deprecated)

Parameters

const char *guid: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
wmi_notify_handler handler: Function to handle notifications
void *data: Data to be returned to handler when event is fired

Description

Register a handler for events sent to the ACPI-WMI mapper device.

Return

acpi_status signaling success or error.

acpi_status wmi_remove_notify_handler(const char *guid)¶: Unregister handler for WMI events (deprecated)

Parameters

const char *guid: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba

Description

Unregister handler for events sent to the ACPI-WMI mapper device.

Return

acpi_status signaling success or error.

acpi_status wmi_get_event_data(u32 event, struct acpi_buffer *out)¶: Get WMI data associated with an event (deprecated)

Parameters

u32 event: Event to find
struct acpi_buffer *out: Buffer to hold event data

Description

Get extra data associated with an WMI event, the caller needs to free out.

Return

acpi_status signaling success or error.

bool wmi_has_guid(const char *guid_string)¶: Check if a GUID is available

Parameters

const char *guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba

Description

Check if a given GUID is defined by _WDG.

Return

True if GUID is available, false otherwise.

char *wmi_get_acpi_device_uid(const char *guid_string)¶: Get _UID name of ACPI device that defines GUID (deprecated)

Parameters

const char *guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba

Description

Find the _UID of ACPI device associated with this WMI GUID.

Return

The ACPI _UID field value or NULL if the WMI GUID was not found.

void wmi_driver_unregister(struct wmi_driver *driver)¶: Unregister a WMI driver

Parameters

struct wmi_driver *driver: WMI driver to unregister

Description

Unregisters a WMI driver from the WMI bus.

The Linux Kernel

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WMI Driver API¶