3  * Backlight Lowlevel Control Abstraction
14 #include <linux/backlight.h>
22 #include <asm/backlight.h>
28  * The backlight core supports implementing backlight drivers.
30  * A backlight driver registers a driver using
31  * devm_backlight_device_register(). The properties of the backlight
34  * the update_status() operation is called. The backlight driver shall
35  * implement this operation and use it to adjust backlight.
37  * Several sysfs attributes are provided by the backlight core::
43  * See Documentation/ABI/stable/sysfs-class-backlight for the full list.
45  * The backlight can be adjusted using the sysfs interface, and
46  * the backlight driver may also support adjusting backlight using
54  * When the backlight changes this is reported to user-space using
57  * a hot-key to adjust backlight, the driver must notify the backlight
60  * The backlight driver core receives notifications from fbdev and
62  * FBIOBLANK ioctrl, results in a change in the backlight state the
87  * framebuffer driver. The backlight core only cares about FB_BLANK_UNBLANK
91  * There may be several fbdev's connected to the backlight device,
93  * if there is a change in backlight for the specified fbdev.
372 	.name = "backlight",
378  * backlight_force_update - tell the backlight subsystem that hardware state
380  * @bd: the backlight device to update
383  * Updates the internal state of the backlight in response to a hardware event,
384  * and generates an uevent to notify userspace. A backlight driver shall call
385  * backlight_force_update() when the backlight is changed using, for example,
437 			WARN(1, "%s: invalid backlight type", name);  in backlight_device_register()
473 /** backlight_device_get_by_type - find first backlight device of a type
474  * @type: the type of backlight device
476  * Look up the first backlight device of the specified type
480  * Pointer to backlight device if any was found. Otherwise NULL.
501  * backlight_device_get_by_name - Get backlight device by name
504  * This function looks up a backlight device by its name. It obtains a reference
505  * on the backlight device and it is the caller's responsibility to drop the
509  * A pointer to the backlight device if found, otherwise NULL.
549 	struct backlight_device *backlight = *(struct backlight_device **)res;  in devm_backlight_device_release()  local
551 	backlight_device_unregister(backlight);  in devm_backlight_device_release()
563  * devm_backlight_device_register - register a new backlight device
568  * @ops: the backlight operations structure
569  * @props: the backlight properties
571  * Creates and registers new backlight device. When a backlight device
577  * struct backlight on success, or an ERR_PTR on error
584 	struct backlight_device **ptr, *backlight;  in devm_backlight_device_register()  local
591 	backlight = backlight_device_register(name, parent, devdata, ops,  in devm_backlight_device_register()
593 	if (!IS_ERR(backlight)) {  in devm_backlight_device_register()
594 		*ptr = backlight;  in devm_backlight_device_register()
600 	return backlight;  in devm_backlight_device_register()
605  * devm_backlight_device_unregister - unregister backlight device
607  * @bd: the backlight device to unregister
609  * Deallocates a backlight allocated with devm_backlight_device_register().
631  * of_find_backlight_by_node() - find backlight device by device-tree node
632  * @node: device-tree node of the backlight device
634  * Returns a pointer to the backlight device corresponding to the given DT
635  * node or NULL if no such backlight device exists or if the device hasn't
638  * This function obtains a reference on the backlight device and it is the
640  * the backlight device's .dev field.
662 		np = of_parse_phandle(dev->of_node, "backlight", 0);  in of_find_backlight()
682  * devm_of_find_backlight - find backlight for a device
685  * This function looks for a property named 'backlight' on the DT node
686  * connected to @dev and looks up the backlight device. The lookup is
687  * device managed so the reference to the backlight device is automatically
692  * A pointer to the backlight device if found.
693  * Error pointer -EPROBE_DEFER if the DT property is set, but no backlight
694  * device is found. NULL if there's no backlight property.
723 		pr_warn("Unable to create backlight class; errno = %d\n", ret);  in backlight_class_init()
742 MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");