1 files changed, 307 insertions, 127 deletions

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 3fccb6d3c8c3..1e9b7e85d99a 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Backlight Lowlevel Control Abstraction
  *
@@ -14,73 +15,103 @@
 #include <linux/notifier.h>
 #include <linux/ctype.h>
 #include <linux/err.h>
-#include <linux/fb.h>
 #include <linux/slab.h>
+#include <linux/of.h>
 
 #ifdef CONFIG_PMAC_BACKLIGHT
 #include <asm/backlight.h>
 #endif
 
+/**
+ * DOC: overview
+ *
+ * The backlight core supports implementing backlight drivers.
+ *
+ * A backlight driver registers a driver using
+ * devm_backlight_device_register(). The properties of the backlight
+ * driver such as type and max_brightness must be specified.
+ * When the core detect changes in for example brightness or power state
+ * the update_status() operation is called. The backlight driver shall
+ * implement this operation and use it to adjust backlight.
+ *
+ * Several sysfs attributes are provided by the backlight core::
+ *
+ * - brightness         R/W, set the requested brightness level
+ * - actual_brightness  RO, the brightness level used by the HW
+ * - max_brightness     RO, the maximum  brightness level supported
+ *
+ * See Documentation/ABI/stable/sysfs-class-backlight for the full list.
+ *
+ * The backlight can be adjusted using the sysfs interface, and
+ * the backlight driver may also support adjusting backlight using
+ * a hot-key or some other platform or firmware specific way.
+ *
+ * The driver must implement the get_brightness() operation if
+ * the HW do not support all the levels that can be specified in
+ * brightness, thus providing user-space access to the actual level
+ * via the actual_brightness attribute.
+ *
+ * When the backlight changes this is reported to user-space using
+ * an uevent connected to the actual_brightness attribute.
+ * When brightness is set by platform specific means, for example
+ * a hot-key to adjust backlight, the driver must notify the backlight
+ * core that brightness has changed using backlight_force_update().
+ *
+ * Display drives can control the backlight device's status using
+ * backlight_notify_blank() and backlight_notify_blank_all(). If this
+ * results in a change in the backlight state the functions call the
+ * update_status() operation.
+ */
+
+static struct list_head backlight_dev_list;
+static struct mutex backlight_dev_list_mutex;
+
 static const char *const backlight_types[] = {
 	[BACKLIGHT_RAW] = "raw",
 	[BACKLIGHT_PLATFORM] = "platform",
 	[BACKLIGHT_FIRMWARE] = "firmware",
 };
 
-#if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
-			   defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
-/* This callback gets called when something important happens inside a
- * framebuffer driver. We're looking if that important event is blanking,
- * and if it is, we're switching backlight power as well ...
- */
-static int fb_notifier_callback(struct notifier_block *self,
-				unsigned long event, void *data)
+static const char *const backlight_scale_types[] = {
+	[BACKLIGHT_SCALE_UNKNOWN]	= "unknown",
+	[BACKLIGHT_SCALE_LINEAR]	= "linear",
+	[BACKLIGHT_SCALE_NON_LINEAR]	= "non-linear",
+};
+
+void backlight_notify_blank(struct backlight_device *bd, struct device *display_dev,
+			    bool fb_on, bool prev_fb_on)
 {
-	struct backlight_device *bd;
-	struct fb_event *evdata = data;
+	guard(mutex)(&bd->ops_lock);
 
-	/* If we aren't interested in this event, skip it immediately ... */
-	if (event != FB_EVENT_BLANK && event != FB_EVENT_CONBLANK)
-		return 0;
+	if (!bd->ops)
+		return;
+	if (bd->ops->controls_device && !bd->ops->controls_device(bd, display_dev))
+		return;
 
-	bd = container_of(self, struct backlight_device, fb_notif);
-	mutex_lock(&bd->ops_lock);
-	if (bd->ops)
-		if (!bd->ops->check_fb ||
-		    bd->ops->check_fb(bd, evdata->info)) {
-			bd->props.fb_blank = *(int *)evdata->data;
-			if (bd->props.fb_blank == FB_BLANK_UNBLANK)
-				bd->props.state &= ~BL_CORE_FBBLANK;
-			else
-				bd->props.state |= BL_CORE_FBBLANK;
+	if (fb_on && (!prev_fb_on || !bd->use_count)) {
+		if (!bd->use_count++) {
+			bd->props.state &= ~BL_CORE_FBBLANK;
 			backlight_update_status(bd);
 		}
-	mutex_unlock(&bd->ops_lock);
-	return 0;
+	} else if (!fb_on && prev_fb_on && bd->use_count) {
+		if (!(--bd->use_count)) {
+			bd->props.state |= BL_CORE_FBBLANK;
+			backlight_update_status(bd);
+		}
+	}
 }
+EXPORT_SYMBOL(backlight_notify_blank);
 
-static int backlight_register_fb(struct backlight_device *bd)
+void backlight_notify_blank_all(struct device *display_dev, bool fb_on, bool prev_fb_on)
 {
-	memset(&bd->fb_notif, 0, sizeof(bd->fb_notif));
-	bd->fb_notif.notifier_call = fb_notifier_callback;
+	struct backlight_device *bd;
 
-	return fb_register_client(&bd->fb_notif);
-}
+	guard(mutex)(&backlight_dev_list_mutex);
 
-static void backlight_unregister_fb(struct backlight_device *bd)
-{
-	fb_unregister_client(&bd->fb_notif);
-}
-#else
-static inline int backlight_register_fb(struct backlight_device *bd)
-{
-	return 0;
+	list_for_each_entry(bd, &backlight_dev_list, entry)
+		backlight_notify_blank(bd, display_dev, fb_on, prev_fb_on);
 }
-
-static inline void backlight_unregister_fb(struct backlight_device *bd)
-{
-}
-#endif /* CONFIG_FB */
+EXPORT_SYMBOL(backlight_notify_blank_all);
 
 static void backlight_generate_event(struct backlight_device *bd,
 				     enum backlight_update_reason reason)
@@ -103,20 +134,20 @@ static void backlight_generate_event(struct backlight_device *bd,
 	sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
 }
 
-static ssize_t backlight_show_power(struct device *dev,
-		struct device_attribute *attr, char *buf)
+static ssize_t bl_power_show(struct device *dev, struct device_attribute *attr,
+		char *buf)
 {
 	struct backlight_device *bd = to_backlight_device(dev);
 
 	return sprintf(buf, "%d\n", bd->props.power);
 }
 
-static ssize_t backlight_store_power(struct device *dev,
-		struct device_attribute *attr, const char *buf, size_t count)
+static ssize_t bl_power_store(struct device *dev, struct device_attribute *attr,
+		const char *buf, size_t count)
 {
 	int rc;
 	struct backlight_device *bd = to_backlight_device(dev);
-	unsigned long power;
+	unsigned long power, old_power;
 
 	rc = kstrtoul(buf, 0, &power);
 	if (rc)
@@ -127,17 +158,24 @@ static ssize_t backlight_store_power(struct device *dev,
 	if (bd->ops) {
 		pr_debug("set power to %lu\n", power);
 		if (bd->props.power != power) {
+			old_power = bd->props.power;
 			bd->props.power = power;
-			backlight_update_status(bd);
+			rc = backlight_update_status(bd);
+			if (rc)
+				bd->props.power = old_power;
+			else
+				rc = count;
+		} else {
+			rc = count;
 		}
-		rc = count;
 	}
 	mutex_unlock(&bd->ops_lock);
 
 	return rc;
 }
+static DEVICE_ATTR_RW(bl_power);
 
-static ssize_t backlight_show_brightness(struct device *dev,
+static ssize_t brightness_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct backlight_device *bd = to_backlight_device(dev);
@@ -145,18 +183,10 @@ static ssize_t backlight_show_brightness(struct device *dev,
 	return sprintf(buf, "%d\n", bd->props.brightness);
 }
 
-static ssize_t backlight_store_brightness(struct device *dev,
-		struct device_attribute *attr, const char *buf, size_t count)
+int backlight_device_set_brightness(struct backlight_device *bd,
+				    unsigned long brightness)
 {
-	int rc;
-	struct backlight_device *bd = to_backlight_device(dev);
-	unsigned long brightness;
-
-	rc = kstrtoul(buf, 0, &brightness);
-	if (rc)
-		return rc;
-
-	rc = -ENXIO;
+	int rc = -ENXIO;
 
 	mutex_lock(&bd->ops_lock);
 	if (bd->ops) {
@@ -165,8 +195,7 @@ static ssize_t backlight_store_brightness(struct device *dev,
 		else {
 			pr_debug("set brightness to %lu\n", brightness);
 			bd->props.brightness = brightness;
-			backlight_update_status(bd);
-			rc = count;
+			rc = backlight_update_status(bd);
 		}
 	}
 	mutex_unlock(&bd->ops_lock);
@@ -175,38 +204,74 @@ static ssize_t backlight_store_brightness(struct device *dev,
 
 	return rc;
 }
+EXPORT_SYMBOL(backlight_device_set_brightness);
 
-static ssize_t backlight_show_type(struct device *dev,
-		struct device_attribute *attr, char *buf)
+static ssize_t brightness_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	int rc;
+	struct backlight_device *bd = to_backlight_device(dev);
+	unsigned long brightness;
+
+	rc = kstrtoul(buf, 0, &brightness);
+	if (rc)
+		return rc;
+
+	rc = backlight_device_set_brightness(bd, brightness);
+
+	return rc ? rc : count;
+}
+static DEVICE_ATTR_RW(brightness);
+
+static ssize_t type_show(struct device *dev, struct device_attribute *attr,
+		char *buf)
 {
 	struct backlight_device *bd = to_backlight_device(dev);
 
 	return sprintf(buf, "%s\n", backlight_types[bd->props.type]);
 }
+static DEVICE_ATTR_RO(type);
 
-static ssize_t backlight_show_max_brightness(struct device *dev,
+static ssize_t max_brightness_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct backlight_device *bd = to_backlight_device(dev);
 
 	return sprintf(buf, "%d\n", bd->props.max_brightness);
 }
+static DEVICE_ATTR_RO(max_brightness);
 
-static ssize_t backlight_show_actual_brightness(struct device *dev,
+static ssize_t actual_brightness_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	int rc = -ENXIO;
 	struct backlight_device *bd = to_backlight_device(dev);
 
 	mutex_lock(&bd->ops_lock);
-	if (bd->ops && bd->ops->get_brightness)
-		rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
+	if (bd->ops && bd->ops->get_brightness) {
+		rc = bd->ops->get_brightness(bd);
+		if (rc >= 0)
+			rc = sprintf(buf, "%d\n", rc);
+	} else {
+		rc = sprintf(buf, "%d\n", bd->props.brightness);
+	}
 	mutex_unlock(&bd->ops_lock);
 
 	return rc;
 }
+static DEVICE_ATTR_RO(actual_brightness);
 
-static struct class *backlight_class;
+static ssize_t scale_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct backlight_device *bd = to_backlight_device(dev);
+
+	if (WARN_ON(bd->props.scale > BACKLIGHT_SCALE_NON_LINEAR))
+		return sprintf(buf, "unknown\n");
+
+	return sprintf(buf, "%s\n", backlight_scale_types[bd->props.scale]);
+}
+static DEVICE_ATTR_RO(scale);
 
 #ifdef CONFIG_PM_SLEEP
 static int backlight_suspend(struct device *dev)
@@ -247,49 +312,56 @@ static void bl_device_release(struct device *dev)
 	kfree(bd);
 }
 
-static struct device_attribute bl_device_attributes[] = {
-	__ATTR(bl_power, 0644, backlight_show_power, backlight_store_power),
-	__ATTR(brightness, 0644, backlight_show_brightness,
-		     backlight_store_brightness),
-	__ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
-		     NULL),
-	__ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
-	__ATTR(type, 0444, backlight_show_type, NULL),
-	__ATTR_NULL,
+static struct attribute *bl_device_attrs[] = {
+	&dev_attr_bl_power.attr,
+	&dev_attr_brightness.attr,
+	&dev_attr_actual_brightness.attr,
+	&dev_attr_max_brightness.attr,
+	&dev_attr_scale.attr,
+	&dev_attr_type.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(bl_device);
+
+static const struct class backlight_class = {
+	.name = "backlight",
+	.dev_groups = bl_device_groups,
+	.pm = &backlight_class_dev_pm_ops,
 };
 
 /**
  * backlight_force_update - tell the backlight subsystem that hardware state
  *   has changed
  * @bd: the backlight device to update
+ * @reason: reason for update
  *
  * Updates the internal state of the backlight in response to a hardware event,
- * and generate a uevent to notify userspace
+ * and generates an uevent to notify userspace. A backlight driver shall call
+ * backlight_force_update() when the backlight is changed using, for example,
+ * a hot-key. The updated brightness is read using get_brightness() and the
+ * brightness value is reported using an uevent.
  */
 void backlight_force_update(struct backlight_device *bd,
 			    enum backlight_update_reason reason)
 {
+	int brightness;
+
 	mutex_lock(&bd->ops_lock);
-	if (bd->ops && bd->ops->get_brightness)
-		bd->props.brightness = bd->ops->get_brightness(bd);
+	if (bd->ops && bd->ops->get_brightness) {
+		brightness = bd->ops->get_brightness(bd);
+		if (brightness >= 0)
+			bd->props.brightness = brightness;
+		else
+			dev_err(&bd->dev,
+				"Could not update brightness from device: %pe\n",
+				ERR_PTR(brightness));
+	}
 	mutex_unlock(&bd->ops_lock);
 	backlight_generate_event(bd, reason);
 }
 EXPORT_SYMBOL(backlight_force_update);
 
-/**
- * backlight_device_register - create and register a new object of
- *   backlight_device class.
- * @name: the name of the new object(must be the same as the name of the
- *   respective framebuffer device).
- * @parent: a pointer to the parent device
- * @devdata: an optional pointer to be stored for private driver use. The
- *   methods may retrieve it by using bl_get_data(bd).
- * @ops: the backlight operations structure.
- *
- * Creates and registers new backlight device. Returns either an
- * ERR_PTR() or a pointer to the newly allocated device.
- */
+/* deprecated - use devm_backlight_device_register() */
 struct backlight_device *backlight_device_register(const char *name,
 	struct device *parent, void *devdata, const struct backlight_ops *ops,
 	const struct backlight_properties *props)
@@ -306,7 +378,7 @@ struct backlight_device *backlight_device_register(const char *name,
 	mutex_init(&new_bd->update_lock);
 	mutex_init(&new_bd->ops_lock);
 
-	new_bd->dev.class = backlight_class;
+	new_bd->dev.class = &backlight_class;
 	new_bd->dev.parent = parent;
 	new_bd->dev.release = bl_device_release;
 	dev_set_name(&new_bd->dev, "%s", name);
@@ -326,13 +398,7 @@ struct backlight_device *backlight_device_register(const char *name,
 
 	rc = device_register(&new_bd->dev);
 	if (rc) {
-		kfree(new_bd);
-		return ERR_PTR(rc);
-	}
-
-	rc = backlight_register_fb(new_bd);
-	if (rc) {
-		device_unregister(&new_bd->dev);
+		put_device(&new_bd->dev);
 		return ERR_PTR(rc);
 	}
 
@@ -345,32 +411,83 @@ struct backlight_device *backlight_device_register(const char *name,
 	mutex_unlock(&pmac_backlight_mutex);
 #endif
 
+	mutex_lock(&backlight_dev_list_mutex);
+	list_add(&new_bd->entry, &backlight_dev_list);
+	mutex_unlock(&backlight_dev_list_mutex);
+
 	return new_bd;
 }
 EXPORT_SYMBOL(backlight_device_register);
 
+/** backlight_device_get_by_type - find first backlight device of a type
+ * @type: the type of backlight device
+ *
+ * Look up the first backlight device of the specified type
+ *
+ * RETURNS:
+ *
+ * Pointer to backlight device if any was found. Otherwise NULL.
+ */
+struct backlight_device *backlight_device_get_by_type(enum backlight_type type)
+{
+	bool found = false;
+	struct backlight_device *bd;
+
+	mutex_lock(&backlight_dev_list_mutex);
+	list_for_each_entry(bd, &backlight_dev_list, entry) {
+		if (bd->props.type == type) {
+			found = true;
+			break;
+		}
+	}
+	mutex_unlock(&backlight_dev_list_mutex);
+
+	return found ? bd : NULL;
+}
+EXPORT_SYMBOL(backlight_device_get_by_type);
+
 /**
- * backlight_device_unregister - unregisters a backlight device object.
- * @bd: the backlight device object to be unregistered and freed.
+ * backlight_device_get_by_name - Get backlight device by name
+ * @name: Device name
+ *
+ * This function looks up a backlight device by its name. It obtains a reference
+ * on the backlight device and it is the caller's responsibility to drop the
+ * reference by calling put_device().
  *
- * Unregisters a previously registered via backlight_device_register object.
+ * Returns:
+ * A pointer to the backlight device if found, otherwise NULL.
  */
+struct backlight_device *backlight_device_get_by_name(const char *name)
+{
+	struct device *dev;
+
+	dev = class_find_device_by_name(&backlight_class, name);
+
+	return dev ? to_backlight_device(dev) : NULL;
+}
+EXPORT_SYMBOL(backlight_device_get_by_name);
+
+/* deprecated - use devm_backlight_device_unregister() */
 void backlight_device_unregister(struct backlight_device *bd)
 {
 	if (!bd)
 		return;
 
+	mutex_lock(&backlight_dev_list_mutex);
+	list_del(&bd->entry);
+	mutex_unlock(&backlight_dev_list_mutex);
+
 #ifdef CONFIG_PMAC_BACKLIGHT
 	mutex_lock(&pmac_backlight_mutex);
 	if (pmac_backlight == bd)
 		pmac_backlight = NULL;
 	mutex_unlock(&pmac_backlight_mutex);
 #endif
+
 	mutex_lock(&bd->ops_lock);
 	bd->ops = NULL;
 	mutex_unlock(&bd->ops_lock);
 
-	backlight_unregister_fb(bd);
 	device_unregister(&bd->dev);
 }
 EXPORT_SYMBOL(backlight_device_unregister);
@@ -391,19 +508,21 @@ static int devm_backlight_device_match(struct device *dev, void *res,
 }
 
 /**
- * devm_backlight_device_register - resource managed backlight_device_register()
+ * devm_backlight_device_register - register a new backlight device
  * @dev: the device to register
  * @name: the name of the device
- * @parent: a pointer to the parent device
+ * @parent: a pointer to the parent device (often the same as @dev)
  * @devdata: an optional pointer to be stored for private driver use
  * @ops: the backlight operations structure
  * @props: the backlight properties
  *
- * @return a struct backlight on success, or an ERR_PTR on error
+ * Creates and registers new backlight device. When a backlight device
+ * is registered the configuration must be specified in the @props
+ * parameter. See description of &backlight_properties.
  *
- * Managed backlight_device_register(). The backlight_device returned
- * from this function are automatically freed on driver detach.
- * See backlight_device_register() for more information.
+ * RETURNS:
+ *
+ * struct backlight on success, or an ERR_PTR on error
  */
 struct backlight_device *devm_backlight_device_register(struct device *dev,
 	const char *name, struct device *parent, void *devdata,
@@ -431,13 +550,13 @@ struct backlight_device *devm_backlight_device_register(struct device *dev,
 EXPORT_SYMBOL(devm_backlight_device_register);
 
 /**
- * devm_backlight_device_unregister - resource managed backlight_device_unregister()
+ * devm_backlight_device_unregister - unregister backlight device
  * @dev: the device to unregister
  * @bd: the backlight device to unregister
  *
- * Deallocated a backlight allocated with devm_backlight_device_register().
+ * Deallocates a backlight allocated with devm_backlight_device_register().
  * Normally this function will not need to be called and the resource management
- * code will ensure that the resource is freed.
+ * code will ensure that the resources are freed.
  */
 void devm_backlight_device_unregister(struct device *dev,
 				struct backlight_device *bd)
@@ -472,29 +591,90 @@ struct backlight_device *of_find_backlight_by_node(struct device_node *node)
 {
 	struct device *dev;
 
-	dev = class_find_device(backlight_class, NULL, node, of_parent_match);
+	dev = class_find_device(&backlight_class, NULL, node, of_parent_match);
 
 	return dev ? to_backlight_device(dev) : NULL;
 }
 EXPORT_SYMBOL(of_find_backlight_by_node);
 #endif
 
+static struct backlight_device *of_find_backlight(struct device *dev)
+{
+	struct backlight_device *bd = NULL;
+	struct device_node *np;
+
+	if (!dev)
+		return NULL;
+
+	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
+		np = of_parse_phandle(dev->of_node, "backlight", 0);
+		if (np) {
+			bd = of_find_backlight_by_node(np);
+			of_node_put(np);
+			if (!bd)
+				return ERR_PTR(-EPROBE_DEFER);
+		}
+	}
+
+	return bd;
+}
+
+static void devm_backlight_release(void *data)
+{
+	struct backlight_device *bd = data;
+
+	put_device(&bd->dev);
+}
+
+/**
+ * devm_of_find_backlight - find backlight for a device
+ * @dev: the device
+ *
+ * This function looks for a property named 'backlight' on the DT node
+ * connected to @dev and looks up the backlight device. The lookup is
+ * device managed so the reference to the backlight device is automatically
+ * dropped on driver detach.
+ *
+ * RETURNS:
+ *
+ * A pointer to the backlight device if found.
+ * Error pointer -EPROBE_DEFER if the DT property is set, but no backlight
+ * device is found. NULL if there's no backlight property.
+ */
+struct backlight_device *devm_of_find_backlight(struct device *dev)
+{
+	struct backlight_device *bd;
+	int ret;
+
+	bd = of_find_backlight(dev);
+	if (IS_ERR_OR_NULL(bd))
+		return bd;
+	ret = devm_add_action_or_reset(dev, devm_backlight_release, bd);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return bd;
+}
+EXPORT_SYMBOL(devm_of_find_backlight);
+
 static void __exit backlight_class_exit(void)
 {
-	class_destroy(backlight_class);
+	class_unregister(&backlight_class);
 }
 
 static int __init backlight_class_init(void)
 {
-	backlight_class = class_create(THIS_MODULE, "backlight");
-	if (IS_ERR(backlight_class)) {
-		pr_warn("Unable to create backlight class; errno = %ld\n",
-			PTR_ERR(backlight_class));
-		return PTR_ERR(backlight_class);
+	int ret;
+
+	ret = class_register(&backlight_class);
+	if (ret) {
+		pr_warn("Unable to create backlight class; errno = %d\n", ret);
+		return ret;
 	}
 
-	backlight_class->dev_attrs = bl_device_attributes;
-	backlight_class->pm = &backlight_class_dev_pm_ops;
+	INIT_LIST_HEAD(&backlight_dev_list);
+	mutex_init(&backlight_dev_list_mutex);
+
 	return 0;
 }