diff options
Diffstat (limited to 'drivers/video/backlight/backlight.c')
| -rw-r--r-- | drivers/video/backlight/backlight.c | 690 |
1 files changed, 690 insertions, 0 deletions
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c new file mode 100644 index 000000000..fc9bb303e --- /dev/null +++ b/drivers/video/backlight/backlight.c @@ -0,0 +1,690 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Backlight Lowlevel Control Abstraction + * + * Copyright (C) 2003,2004 Hewlett-Packard Company + * + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/device.h> +#include <linux/backlight.h> +#include <linux/notifier.h> +#include <linux/ctype.h> +#include <linux/err.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", +}; + +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) +{ + guard(mutex)(&bd->ops_lock); + + if (!bd->ops) + return; + if (bd->ops->controls_device && !bd->ops->controls_device(bd, display_dev)) + return; + + if (fb_on && (!prev_fb_on || !bd->use_count)) { + if (!bd->use_count++) { + bd->props.state &= ~BL_CORE_FBBLANK; + backlight_update_status(bd); + } + } 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); + +void backlight_notify_blank_all(struct device *display_dev, bool fb_on, bool prev_fb_on) +{ + struct backlight_device *bd; + + guard(mutex)(&backlight_dev_list_mutex); + + list_for_each_entry(bd, &backlight_dev_list, entry) + backlight_notify_blank(bd, display_dev, fb_on, prev_fb_on); +} +EXPORT_SYMBOL(backlight_notify_blank_all); + +static void backlight_generate_event(struct backlight_device *bd, + enum backlight_update_reason reason) +{ + char *envp[2]; + + switch (reason) { + case BACKLIGHT_UPDATE_SYSFS: + envp[0] = "SOURCE=sysfs"; + break; + case BACKLIGHT_UPDATE_HOTKEY: + envp[0] = "SOURCE=hotkey"; + break; + default: + envp[0] = "SOURCE=unknown"; + break; + } + envp[1] = NULL; + kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp); + sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness"); +} + +static ssize_t bl_power_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct backlight_device *bd = to_backlight_device(dev); + + return sysfs_emit(buf, "%d\n", bd->props.power); +} + +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, old_power; + + rc = kstrtoul(buf, 0, &power); + if (rc) + return rc; + + rc = -ENXIO; + mutex_lock(&bd->ops_lock); + 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; + rc = backlight_update_status(bd); + if (rc) + bd->props.power = old_power; + else + rc = count; + } else { + rc = count; + } + } + mutex_unlock(&bd->ops_lock); + + return rc; +} +static DEVICE_ATTR_RW(bl_power); + +static ssize_t brightness_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct backlight_device *bd = to_backlight_device(dev); + + return sysfs_emit(buf, "%d\n", bd->props.brightness); +} + +int backlight_device_set_brightness(struct backlight_device *bd, + unsigned long brightness) +{ + int rc = -ENXIO; + + mutex_lock(&bd->ops_lock); + if (bd->ops) { + if (brightness > bd->props.max_brightness) + rc = -EINVAL; + else { + pr_debug("set brightness to %lu\n", brightness); + bd->props.brightness = brightness; + rc = backlight_update_status(bd); + } + } + mutex_unlock(&bd->ops_lock); + + backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS); + + return rc; +} +EXPORT_SYMBOL(backlight_device_set_brightness); + +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 sysfs_emit(buf, "%s\n", backlight_types[bd->props.type]); +} +static DEVICE_ATTR_RO(type); + +static ssize_t max_brightness_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct backlight_device *bd = to_backlight_device(dev); + + return sysfs_emit(buf, "%d\n", bd->props.max_brightness); +} +static DEVICE_ATTR_RO(max_brightness); + +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 = bd->ops->get_brightness(bd); + if (rc >= 0) + rc = sysfs_emit(buf, "%d\n", rc); + } else { + rc = sysfs_emit(buf, "%d\n", bd->props.brightness); + } + mutex_unlock(&bd->ops_lock); + + return rc; +} +static DEVICE_ATTR_RO(actual_brightness); + +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 sysfs_emit(buf, "unknown\n"); + + return sysfs_emit(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) +{ + struct backlight_device *bd = to_backlight_device(dev); + + mutex_lock(&bd->ops_lock); + if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) { + bd->props.state |= BL_CORE_SUSPENDED; + backlight_update_status(bd); + } + mutex_unlock(&bd->ops_lock); + + return 0; +} + +static int backlight_resume(struct device *dev) +{ + struct backlight_device *bd = to_backlight_device(dev); + + mutex_lock(&bd->ops_lock); + if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) { + bd->props.state &= ~BL_CORE_SUSPENDED; + backlight_update_status(bd); + } + mutex_unlock(&bd->ops_lock); + + return 0; +} +#endif + +static SIMPLE_DEV_PM_OPS(backlight_class_dev_pm_ops, backlight_suspend, + backlight_resume); + +static void bl_device_release(struct device *dev) +{ + struct backlight_device *bd = to_backlight_device(dev); + kfree(bd); +} + +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 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) { + 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); + +/* 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) +{ + struct backlight_device *new_bd; + int rc; + + pr_debug("backlight_device_register: name=%s\n", name); + + new_bd = kzalloc_obj(struct backlight_device); + if (!new_bd) + return ERR_PTR(-ENOMEM); + + mutex_init(&new_bd->update_lock); + mutex_init(&new_bd->ops_lock); + + 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); + dev_set_drvdata(&new_bd->dev, devdata); + + /* Set default properties */ + if (props) { + memcpy(&new_bd->props, props, + sizeof(struct backlight_properties)); + if (props->type <= 0 || props->type >= BACKLIGHT_TYPE_MAX) { + WARN(1, "%s: invalid backlight type", name); + new_bd->props.type = BACKLIGHT_RAW; + } + } else { + new_bd->props.type = BACKLIGHT_RAW; + } + + rc = device_register(&new_bd->dev); + if (rc) { + put_device(&new_bd->dev); + return ERR_PTR(rc); + } + + new_bd->ops = ops; + +#ifdef CONFIG_PMAC_BACKLIGHT + mutex_lock(&pmac_backlight_mutex); + if (!pmac_backlight) + pmac_backlight = new_bd; + 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_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(). + * + * 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); + + device_unregister(&bd->dev); +} +EXPORT_SYMBOL(backlight_device_unregister); + +static void devm_backlight_device_release(struct device *dev, void *res) +{ + struct backlight_device *backlight = *(struct backlight_device **)res; + + backlight_device_unregister(backlight); +} + +static int devm_backlight_device_match(struct device *dev, void *res, + void *data) +{ + struct backlight_device **r = res; + + return *r == data; +} + +/** + * 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 (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 + * + * 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: + * + * 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, + const struct backlight_ops *ops, + const struct backlight_properties *props) +{ + struct backlight_device **ptr, *backlight; + + ptr = devres_alloc(devm_backlight_device_release, sizeof(*ptr), + GFP_KERNEL); + if (!ptr) + return ERR_PTR(-ENOMEM); + + backlight = backlight_device_register(name, parent, devdata, ops, + props); + if (!IS_ERR(backlight)) { + *ptr = backlight; + devres_add(dev, ptr); + } else { + devres_free(ptr); + } + + return backlight; +} +EXPORT_SYMBOL(devm_backlight_device_register); + +/** + * devm_backlight_device_unregister - unregister backlight device + * @dev: the device to unregister + * @bd: the backlight device to unregister + * + * 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 resources are freed. + */ +void devm_backlight_device_unregister(struct device *dev, + struct backlight_device *bd) +{ + int rc; + + rc = devres_release(dev, devm_backlight_device_release, + devm_backlight_device_match, bd); + WARN_ON(rc); +} +EXPORT_SYMBOL(devm_backlight_device_unregister); + +#ifdef CONFIG_OF +static int of_parent_match(struct device *dev, const void *data) +{ + return dev->parent && dev->parent->of_node == data; +} + +/** + * of_find_backlight_by_node() - find backlight device by device-tree node + * @node: device-tree node of the backlight device + * + * Returns a pointer to the backlight device corresponding to the given DT + * node or NULL if no such backlight device exists or if the device hasn't + * been probed yet. + * + * This function obtains a reference on the backlight device and it is the + * caller's responsibility to drop the reference by calling put_device() on + * the backlight device's .dev field. + */ +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); + + 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_unregister(&backlight_class); +} + +static int __init backlight_class_init(void) +{ + int ret; + + ret = class_register(&backlight_class); + if (ret) { + pr_warn("Unable to create backlight class; errno = %d\n", ret); + return ret; + } + + INIT_LIST_HEAD(&backlight_dev_list); + mutex_init(&backlight_dev_list_mutex); + + return 0; +} + +/* + * if this is compiled into the kernel, we need to ensure that the + * class is registered before users of the class try to register lcd's + */ +postcore_initcall(backlight_class_init); +module_exit(backlight_class_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>"); +MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction"); |