diff options
Diffstat (limited to 'drivers/video/backlight/backlight.c')
| -rw-r--r-- | drivers/video/backlight/backlight.c | 358 |
1 files changed, 180 insertions, 178 deletions
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c index deb824bef6e2..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 * @@ -14,16 +15,56 @@ #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 struct blocking_notifier_head backlight_notifier; static const char *const backlight_types[] = { [BACKLIGHT_RAW] = "raw", @@ -31,74 +72,46 @@ static const char *const backlight_types[] = { [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 and necessary, 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; - int node = evdata->info->node; - int fb_blank = 0; + 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)) { - fb_blank = *(int *)evdata->data; - if (fb_blank == FB_BLANK_UNBLANK && - !bd->fb_bl_on[node]) { - bd->fb_bl_on[node] = true; - if (!bd->use_count++) { - bd->props.state &= ~BL_CORE_FBBLANK; - bd->props.fb_blank = FB_BLANK_UNBLANK; - backlight_update_status(bd); - } - } else if (fb_blank != FB_BLANK_UNBLANK && - bd->fb_bl_on[node]) { - bd->fb_bl_on[node] = false; - if (!(--bd->use_count)) { - bd->props.state |= BL_CORE_FBBLANK; - bd->props.fb_blank = fb_blank; - backlight_update_status(bd); - } - } + 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; - - return fb_register_client(&bd->fb_notif); -} + struct backlight_device *bd; -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; -} + guard(mutex)(&backlight_dev_list_mutex); -static inline void backlight_unregister_fb(struct backlight_device *bd) -{ + list_for_each_entry(bd, &backlight_dev_list, entry) + backlight_notify_blank(bd, display_dev, fb_on, prev_fb_on); } -#endif /* CONFIG_FB */ +EXPORT_SYMBOL(backlight_notify_blank_all); static void backlight_generate_event(struct backlight_device *bd, enum backlight_update_reason reason) @@ -235,17 +248,30 @@ static ssize_t actual_brightness_show(struct device *dev, 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)); - else + 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) @@ -291,43 +317,51 @@ static struct attribute *bl_device_attrs[] = { &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) @@ -344,7 +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); @@ -368,12 +402,6 @@ struct backlight_device *backlight_device_register(const char *name, return ERR_PTR(rc); } - rc = backlight_register_fb(new_bd); - if (rc) { - device_unregister(&new_bd->dev); - return ERR_PTR(rc); - } - new_bd->ops = ops; #ifdef CONFIG_PMAC_BACKLIGHT @@ -387,13 +415,19 @@ struct backlight_device *backlight_device_register(const char *name, list_add(&new_bd->entry, &backlight_dev_list); mutex_unlock(&backlight_dev_list_mutex); - blocking_notifier_call_chain(&backlight_notifier, - BACKLIGHT_REGISTERED, new_bd); - 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; @@ -413,11 +447,27 @@ struct backlight_device *backlight_device_get_by_type(enum backlight_type type) 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) @@ -434,14 +484,10 @@ void backlight_device_unregister(struct backlight_device *bd) mutex_unlock(&pmac_backlight_mutex); #endif - blocking_notifier_call_chain(&backlight_notifier, - BACKLIGHT_UNREGISTERED, bd); - 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); @@ -462,49 +508,21 @@ static int devm_backlight_device_match(struct device *dev, void *res, } /** - * backlight_register_notifier - get notified of backlight (un)registration - * @nb: notifier block with the notifier to call on backlight (un)registration - * - * @return 0 on success, otherwise a negative error code - * - * Register a notifier to get notified when backlight devices get registered - * or unregistered. - */ -int backlight_register_notifier(struct notifier_block *nb) -{ - return blocking_notifier_chain_register(&backlight_notifier, nb); -} -EXPORT_SYMBOL(backlight_register_notifier); - -/** - * backlight_unregister_notifier - unregister a backlight notifier - * @nb: notifier block to unregister - * - * @return 0 on success, otherwise a negative error code - * - * Register a notifier to get notified when backlight devices get registered - * or unregistered. - */ -int backlight_unregister_notifier(struct notifier_block *nb) -{ - return blocking_notifier_chain_unregister(&backlight_notifier, nb); -} -EXPORT_SYMBOL(backlight_unregister_notifier); - -/** - * 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. + * + * RETURNS: * - * Managed backlight_device_register(). The backlight_device returned - * from this function are automatically freed on driver detach. - * See backlight_device_register() for more information. + * 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, @@ -532,13 +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) @@ -573,29 +591,14 @@ 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 -/** - * of_find_backlight - Get backlight device - * @dev: Device - * - * This function looks for a property named 'backlight' on the DT node - * connected to @dev and looks up the backlight device. - * - * Call backlight_put() to drop the reference on the backlight device. - * - * 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 *of_find_backlight(struct device *dev) +static struct backlight_device *of_find_backlight(struct device *dev) { struct backlight_device *bd = NULL; struct device_node *np; @@ -610,31 +613,33 @@ struct backlight_device *of_find_backlight(struct device *dev) of_node_put(np); if (!bd) return ERR_PTR(-EPROBE_DEFER); - /* - * Note: gpio_backlight uses brightness as - * power state during probe - */ - if (!bd->props.brightness) - bd->props.brightness = bd->props.max_brightness; } } return bd; } -EXPORT_SYMBOL(of_find_backlight); static void devm_backlight_release(void *data) { - backlight_put(data); + struct backlight_device *bd = data; + + put_device(&bd->dev); } /** - * devm_of_find_backlight - Resource-managed of_find_backlight() - * @dev: Device + * devm_of_find_backlight - find backlight for a device + * @dev: the device * - * Device managed version of of_find_backlight(). - * The reference on the backlight device is automatically + * 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) { @@ -644,34 +649,31 @@ struct backlight_device *devm_of_find_backlight(struct device *dev) bd = of_find_backlight(dev); if (IS_ERR_OR_NULL(bd)) return bd; - ret = devm_add_action(dev, devm_backlight_release, bd); - if (ret) { - backlight_put(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_groups = bl_device_groups; - backlight_class->pm = &backlight_class_dev_pm_ops; INIT_LIST_HEAD(&backlight_dev_list); mutex_init(&backlight_dev_list_mutex); - BLOCKING_INIT_NOTIFIER_HEAD(&backlight_notifier); return 0; } |