1 files changed, 489 insertions, 0 deletions
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
new file mode 100644
index 000000000..614653e07
--- /dev/null
+++ b/include/linux/backlight.h
@@ -0,0 +1,489 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Backlight Lowlevel Control Abstraction
+ *
+ * Copyright (C) 2003,2004 Hewlett-Packard Company
+ *
+ */
+
+#ifndef _LINUX_BACKLIGHT_H
+#define _LINUX_BACKLIGHT_H
+
+#include <linux/device.h>
+#include <linux/fb.h>
+#include <linux/mutex.h>
+#include <linux/notifier.h>
+
+/**
+ * enum backlight_update_reason - what method was used to update backlight
+ *
+ * A driver indicates the method (reason) used for updating the backlight
+ * when calling backlight_force_update().
+ */
+enum backlight_update_reason {
+	/**
+	 * @BACKLIGHT_UPDATE_HOTKEY: The backlight was updated using a hot-key.
+	 */
+	BACKLIGHT_UPDATE_HOTKEY,
+
+	/**
+	 * @BACKLIGHT_UPDATE_SYSFS: The backlight was updated using sysfs.
+	 */
+	BACKLIGHT_UPDATE_SYSFS,
+};
+
+/**
+ * enum backlight_type - the type of backlight control
+ *
+ * The type of interface used to control the backlight.
+ */
+enum backlight_type {
+	/**
+	 * @BACKLIGHT_RAW:
+	 *
+	 * The backlight is controlled using hardware registers.
+	 */
+	BACKLIGHT_RAW = 1,
+
+	/**
+	 * @BACKLIGHT_PLATFORM:
+	 *
+	 * The backlight is controlled using a platform-specific interface.
+	 */
+	BACKLIGHT_PLATFORM,
+
+	/**
+	 * @BACKLIGHT_FIRMWARE:
+	 *
+	 * The backlight is controlled using a standard firmware interface.
+	 */
+	BACKLIGHT_FIRMWARE,
+
+	/**
+	 * @BACKLIGHT_TYPE_MAX: Number of entries.
+	 */
+	BACKLIGHT_TYPE_MAX,
+};
+
+/**
+ * enum backlight_notification - the type of notification
+ *
+ * The notifications that is used for notification sent to the receiver
+ * that registered notifications using backlight_register_notifier().
+ */
+enum backlight_notification {
+	/**
+	 * @BACKLIGHT_REGISTERED: The backlight device is registered.
+	 */
+	BACKLIGHT_REGISTERED,
+
+	/**
+	 * @BACKLIGHT_UNREGISTERED: The backlight revice is unregistered.
+	 */
+	BACKLIGHT_UNREGISTERED,
+};
+
+/** enum backlight_scale - the type of scale used for brightness values
+ *
+ * The type of scale used for brightness values.
+ */
+enum backlight_scale {
+	/**
+	 * @BACKLIGHT_SCALE_UNKNOWN: The scale is unknown.
+	 */
+	BACKLIGHT_SCALE_UNKNOWN = 0,
+
+	/**
+	 * @BACKLIGHT_SCALE_LINEAR: The scale is linear.
+	 *
+	 * The linear scale will increase brightness the same for each step.
+	 */
+	BACKLIGHT_SCALE_LINEAR,
+
+	/**
+	 * @BACKLIGHT_SCALE_NON_LINEAR: The scale is not linear.
+	 *
+	 * This is often used when the brightness values tries to adjust to
+	 * the relative perception of the eye demanding a non-linear scale.
+	 */
+	BACKLIGHT_SCALE_NON_LINEAR,
+};
+
+struct backlight_device;
+struct fb_info;
+
+/**
+ * struct backlight_ops - backlight operations
+ *
+ * The backlight operations are specified when the backlight device is registered.
+ */
+struct backlight_ops {
+	/**
+	 * @options: Configure how operations are called from the core.
+	 *
+	 * The options parameter is used to adjust the behaviour of the core.
+	 * Set BL_CORE_SUSPENDRESUME to get the update_status() operation called
+	 * upon suspend and resume.
+	 */
+	unsigned int options;
+
+#define BL_CORE_SUSPENDRESUME	(1 << 0)
+
+	/**
+	 * @update_status: Operation called when properties have changed.
+	 *
+	 * Notify the backlight driver some property has changed.
+	 * The update_status operation is protected by the update_lock.
+	 *
+	 * The backlight driver is expected to use backlight_is_blank()
+	 * to check if the display is blanked and set brightness accordingly.
+	 * update_status() is called when any of the properties has changed.
+	 *
+	 * RETURNS:
+	 *
+	 * 0 on success, negative error code if any failure occurred.
+	 */
+	int (*update_status)(struct backlight_device *);
+
+	/**
+	 * @get_brightness: Return the current backlight brightness.
+	 *
+	 * The driver may implement this as a readback from the HW.
+	 * This operation is optional and if not present then the current
+	 * brightness property value is used.
+	 *
+	 * RETURNS:
+	 *
+	 * A brightness value which is 0 or a positive number.
+	 * On failure a negative error code is returned.
+	 */
+	int (*get_brightness)(struct backlight_device *);
+
+	/**
+	 * @check_fb: Check the framebuffer device.
+	 *
+	 * Check if given framebuffer device is the one bound to this backlight.
+	 * This operation is optional and if not implemented it is assumed that the
+	 * fbdev is always the one bound to the backlight.
+	 *
+	 * RETURNS:
+	 *
+	 * If info is NULL or the info matches the fbdev bound to the backlight return true.
+	 * If info does not match the fbdev bound to the backlight return false.
+	 */
+	int (*check_fb)(struct backlight_device *bd, struct fb_info *info);
+};
+
+/**
+ * struct backlight_properties - backlight properties
+ *
+ * This structure defines all the properties of a backlight.
+ */
+struct backlight_properties {
+	/**
+	 * @brightness: The current brightness requested by the user.
+	 *
+	 * The backlight core makes sure the range is (0 to max_brightness)
+	 * when the brightness is set via the sysfs attribute:
+	 * /sys/class/backlight/<backlight>/brightness.
+	 *
+	 * This value can be set in the backlight_properties passed
+	 * to devm_backlight_device_register() to set a default brightness
+	 * value.
+	 */
+	int brightness;
+
+	/**
+	 * @max_brightness: The maximum brightness value.
+	 *
+	 * This value must be set in the backlight_properties passed to
+	 * devm_backlight_device_register() and shall not be modified by the
+	 * driver after registration.
+	 */
+	int max_brightness;
+
+	/**
+	 * @power: The current power mode.
+	 *
+	 * User space can configure the power mode using the sysfs
+	 * attribute: /sys/class/backlight/<backlight>/bl_power
+	 * When the power property is updated update_status() is called.
+	 *
+	 * The possible values are: (0: full on, 1 to 3: power saving
+	 * modes; 4: full off), see FB_BLANK_XXX.
+	 *
+	 * When the backlight device is enabled @power is set
+	 * to FB_BLANK_UNBLANK. When the backlight device is disabled
+	 * @power is set to FB_BLANK_POWERDOWN.
+	 */
+	int power;
+
+	/**
+	 * @fb_blank: The power state from the FBIOBLANK ioctl.
+	 *
+	 * When the FBIOBLANK ioctl is called @fb_blank is set to the
+	 * blank parameter and the update_status() operation is called.
+	 *
+	 * When the backlight device is enabled @fb_blank is set
+	 * to FB_BLANK_UNBLANK. When the backlight device is disabled
+	 * @fb_blank is set to FB_BLANK_POWERDOWN.
+	 *
+	 * Backlight drivers should avoid using this property. It has been
+	 * replaced by state & BL_CORE_FBLANK (although most drivers should
+	 * use backlight_is_blank() as the preferred means to get the blank
+	 * state).
+	 *
+	 * fb_blank is deprecated and will be removed.
+	 */
+	int fb_blank;
+
+	/**
+	 * @type: The type of backlight supported.
+	 *
+	 * The backlight type allows userspace to make appropriate
+	 * policy decisions based on the backlight type.
+	 *
+	 * This value must be set in the backlight_properties
+	 * passed to devm_backlight_device_register().
+	 */
+	enum backlight_type type;
+
+	/**
+	 * @state: The state of the backlight core.
+	 *
+	 * The state is a bitmask. BL_CORE_FBBLANK is set when the display
+	 * is expected to be blank. BL_CORE_SUSPENDED is set when the
+	 * driver is suspended.
+	 *
+	 * backlight drivers are expected to use backlight_is_blank()
+	 * in their update_status() operation rather than reading the
+	 * state property.
+	 *
+	 * The state is maintained by the core and drivers may not modify it.
+	 */
+	unsigned int state;
+
+#define BL_CORE_SUSPENDED	(1 << 0)	/* backlight is suspended */
+#define BL_CORE_FBBLANK		(1 << 1)	/* backlight is under an fb blank event */
+
+	/**
+	 * @scale: The type of the brightness scale.
+	 */
+	enum backlight_scale scale;
+};
+
+/**
+ * struct backlight_device - backlight device data
+ *
+ * This structure holds all data required by a backlight device.
+ */
+struct backlight_device {
+	/**
+	 * @props: Backlight properties
+	 */
+	struct backlight_properties props;
+
+	/**
+	 * @update_lock: The lock used when calling the update_status() operation.
+	 *
+	 * update_lock is an internal backlight lock that serialise access
+	 * to the update_status() operation. The backlight core holds the update_lock
+	 * when calling the update_status() operation. The update_lock shall not
+	 * be used by backlight drivers.
+	 */
+	struct mutex update_lock;
+
+	/**
+	 * @ops_lock: The lock used around everything related to backlight_ops.
+	 *
+	 * ops_lock is an internal backlight lock that protects the ops pointer
+	 * and is used around all accesses to ops and when the operations are
+	 * invoked. The ops_lock shall not be used by backlight drivers.
+	 */
+	struct mutex ops_lock;
+
+	/**
+	 * @ops: Pointer to the backlight operations.
+	 *
+	 * If ops is NULL, the driver that registered this device has been unloaded,
+	 * and if class_get_devdata() points to something in the body of that driver,
+	 * it is also invalid.
+	 */
+	const struct backlight_ops *ops;
+
+	/**
+	 * @fb_notif: The framebuffer notifier block
+	 */
+	struct notifier_block fb_notif;
+
+	/**
+	 * @entry: List entry of all registered backlight devices
+	 */
+	struct list_head entry;
+
+	/**
+	 * @dev: Parent device.
+	 */
+	struct device dev;
+
+	/**
+	 * @fb_bl_on: The state of individual fbdev's.
+	 *
+	 * Multiple fbdev's may share one backlight device. The fb_bl_on
+	 * records the state of the individual fbdev.
+	 */
+	bool fb_bl_on[FB_MAX];
+
+	/**
+	 * @use_count: The number of uses of fb_bl_on.
+	 */
+	int use_count;
+};
+
+/**
+ * backlight_update_status - force an update of the backlight device status
+ * @bd: the backlight device
+ */
+static inline int backlight_update_status(struct backlight_device *bd)
+{
+	int ret = -ENOENT;
+
+	mutex_lock(&bd->update_lock);
+	if (bd->ops && bd->ops->update_status)
+		ret = bd->ops->update_status(bd);
+	mutex_unlock(&bd->update_lock);
+
+	return ret;
+}
+
+/**
+ * backlight_enable - Enable backlight
+ * @bd: the backlight device to enable
+ */
+static inline int backlight_enable(struct backlight_device *bd)
+{
+	if (!bd)
+		return 0;
+
+	bd->props.power = FB_BLANK_UNBLANK;
+	bd->props.fb_blank = FB_BLANK_UNBLANK;
+	bd->props.state &= ~BL_CORE_FBBLANK;
+
+	return backlight_update_status(bd);
+}
+
+/**
+ * backlight_disable - Disable backlight
+ * @bd: the backlight device to disable
+ */
+static inline int backlight_disable(struct backlight_device *bd)
+{
+	if (!bd)
+		return 0;
+
+	bd->props.power = FB_BLANK_POWERDOWN;
+	bd->props.fb_blank = FB_BLANK_POWERDOWN;
+	bd->props.state |= BL_CORE_FBBLANK;
+
+	return backlight_update_status(bd);
+}
+
+/**
+ * backlight_is_blank - Return true if display is expected to be blank
+ * @bd: the backlight device
+ *
+ * Display is expected to be blank if any of these is true::
+ *
+ *   1) if power in not UNBLANK
+ *   2) if fb_blank is not UNBLANK
+ *   3) if state indicate BLANK or SUSPENDED
+ *
+ * Returns true if display is expected to be blank, false otherwise.
+ */
+static inline bool backlight_is_blank(const struct backlight_device *bd)
+{
+	return bd->props.power != FB_BLANK_UNBLANK ||
+	       bd->props.fb_blank != FB_BLANK_UNBLANK ||
+	       bd->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK);
+}
+
+/**
+ * backlight_get_brightness - Returns the current brightness value
+ * @bd: the backlight device
+ *
+ * Returns the current brightness value, taking in consideration the current
+ * state. If backlight_is_blank() returns true then return 0 as brightness
+ * otherwise return the current brightness property value.
+ *
+ * Backlight drivers are expected to use this function in their update_status()
+ * operation to get the brightness value.
+ */
+static inline int backlight_get_brightness(const struct backlight_device *bd)
+{
+	if (backlight_is_blank(bd))
+		return 0;
+	else
+		return bd->props.brightness;
+}
+
+struct backlight_device *
+backlight_device_register(const char *name, struct device *dev, void *devdata,
+			  const struct backlight_ops *ops,
+			  const struct backlight_properties *props);
+struct backlight_device *
+devm_backlight_device_register(struct device *dev, const char *name,
+			       struct device *parent, void *devdata,
+			       const struct backlight_ops *ops,
+			       const struct backlight_properties *props);
+void backlight_device_unregister(struct backlight_device *bd);
+void devm_backlight_device_unregister(struct device *dev,
+				      struct backlight_device *bd);
+void backlight_force_update(struct backlight_device *bd,
+			    enum backlight_update_reason reason);
+int backlight_register_notifier(struct notifier_block *nb);
+int backlight_unregister_notifier(struct notifier_block *nb);
+struct backlight_device *backlight_device_get_by_name(const char *name);
+struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
+int backlight_device_set_brightness(struct backlight_device *bd,
+				    unsigned long brightness);
+
+#define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
+
+/**
+ * bl_get_data - access devdata
+ * @bl_dev: pointer to backlight device
+ *
+ * When a backlight device is registered the driver has the possibility
+ * to supply a void * devdata. bl_get_data() return a pointer to the
+ * devdata.
+ *
+ * RETURNS:
+ *
+ * pointer to devdata stored while registering the backlight device.
+ */
+static inline void * bl_get_data(struct backlight_device *bl_dev)
+{
+	return dev_get_drvdata(&bl_dev->dev);
+}
+
+#ifdef CONFIG_OF
+struct backlight_device *of_find_backlight_by_node(struct device_node *node);
+#else
+static inline struct backlight_device *
+of_find_backlight_by_node(struct device_node *node)
+{
+	return NULL;
+}
+#endif
+
+#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
+struct backlight_device *devm_of_find_backlight(struct device *dev);
+#else
+static inline struct backlight_device *
+devm_of_find_backlight(struct device *dev)
+{
+	return NULL;
+}
+#endif
+
+#endif