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![Hans de Goede](/assets/img/avatar_default.png)
Some LEDs may have their brightness level changed autonomously (outside of kernel control) by hardware / firmware. This commit adds support for an optional brightness_hw_changed attribute to signal such changes to userspace (if a driver can detect them): What: /sys/class/leds/<led>/brightness_hw_changed Date: January 2017 KernelVersion: 4.11 Description: Last hardware set brightness level for this LED. Some LEDs may be changed autonomously by hardware/firmware. Only LEDs where this happens and the driver can detect this, will have this file. This file supports poll() to detect when the hardware changes the brightness. Reading this file will return the last brightness level set by the hardware, this may be different from the current brightness. Drivers which want to support this, simply add LED_BRIGHT_HW_CHANGED to their flags field and call led_classdev_notify_brightness_hw_changed() with the hardware set brightness when they detect a hardware / firmware triggered brightness change. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
422 lines
9.8 KiB
C
422 lines
9.8 KiB
C
/*
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* LED Class Core
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*
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* Copyright (C) 2005 John Lenz <lenz@cs.wisc.edu>
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* Copyright (C) 2005-2007 Richard Purdie <rpurdie@openedhand.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/ctype.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/leds.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/timer.h>
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#include <uapi/linux/uleds.h>
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#include "leds.h"
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static struct class *leds_class;
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static ssize_t brightness_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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/* no lock needed for this */
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led_update_brightness(led_cdev);
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return sprintf(buf, "%u\n", led_cdev->brightness);
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}
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static ssize_t brightness_store(struct device *dev,
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struct device_attribute *attr, const char *buf, size_t size)
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{
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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unsigned long state;
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ssize_t ret;
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mutex_lock(&led_cdev->led_access);
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if (led_sysfs_is_disabled(led_cdev)) {
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ret = -EBUSY;
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goto unlock;
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}
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ret = kstrtoul(buf, 10, &state);
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if (ret)
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goto unlock;
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if (state == LED_OFF)
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led_trigger_remove(led_cdev);
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led_set_brightness(led_cdev, state);
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ret = size;
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unlock:
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mutex_unlock(&led_cdev->led_access);
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return ret;
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}
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static DEVICE_ATTR_RW(brightness);
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static ssize_t max_brightness_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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return sprintf(buf, "%u\n", led_cdev->max_brightness);
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}
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static DEVICE_ATTR_RO(max_brightness);
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#ifdef CONFIG_LEDS_TRIGGERS
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static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
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static struct attribute *led_trigger_attrs[] = {
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&dev_attr_trigger.attr,
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NULL,
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};
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static const struct attribute_group led_trigger_group = {
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.attrs = led_trigger_attrs,
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};
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#endif
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static struct attribute *led_class_attrs[] = {
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&dev_attr_brightness.attr,
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&dev_attr_max_brightness.attr,
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NULL,
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};
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static const struct attribute_group led_group = {
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.attrs = led_class_attrs,
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};
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static const struct attribute_group *led_groups[] = {
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&led_group,
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#ifdef CONFIG_LEDS_TRIGGERS
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&led_trigger_group,
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#endif
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NULL,
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};
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#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
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static ssize_t brightness_hw_changed_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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if (led_cdev->brightness_hw_changed == -1)
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return -ENODATA;
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return sprintf(buf, "%u\n", led_cdev->brightness_hw_changed);
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}
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static DEVICE_ATTR_RO(brightness_hw_changed);
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static int led_add_brightness_hw_changed(struct led_classdev *led_cdev)
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{
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struct device *dev = led_cdev->dev;
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int ret;
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ret = device_create_file(dev, &dev_attr_brightness_hw_changed);
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if (ret) {
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dev_err(dev, "Error creating brightness_hw_changed\n");
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return ret;
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}
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led_cdev->brightness_hw_changed_kn =
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sysfs_get_dirent(dev->kobj.sd, "brightness_hw_changed");
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if (!led_cdev->brightness_hw_changed_kn) {
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dev_err(dev, "Error getting brightness_hw_changed kn\n");
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device_remove_file(dev, &dev_attr_brightness_hw_changed);
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return -ENXIO;
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}
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return 0;
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}
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static void led_remove_brightness_hw_changed(struct led_classdev *led_cdev)
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{
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sysfs_put(led_cdev->brightness_hw_changed_kn);
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device_remove_file(led_cdev->dev, &dev_attr_brightness_hw_changed);
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}
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void led_classdev_notify_brightness_hw_changed(struct led_classdev *led_cdev,
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enum led_brightness brightness)
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{
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if (WARN_ON(!led_cdev->brightness_hw_changed_kn))
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return;
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led_cdev->brightness_hw_changed = brightness;
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sysfs_notify_dirent(led_cdev->brightness_hw_changed_kn);
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}
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EXPORT_SYMBOL_GPL(led_classdev_notify_brightness_hw_changed);
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#else
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static int led_add_brightness_hw_changed(struct led_classdev *led_cdev)
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{
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return 0;
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}
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static void led_remove_brightness_hw_changed(struct led_classdev *led_cdev)
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{
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}
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#endif
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/**
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* led_classdev_suspend - suspend an led_classdev.
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* @led_cdev: the led_classdev to suspend.
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*/
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void led_classdev_suspend(struct led_classdev *led_cdev)
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{
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led_cdev->flags |= LED_SUSPENDED;
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led_set_brightness_nopm(led_cdev, 0);
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}
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EXPORT_SYMBOL_GPL(led_classdev_suspend);
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/**
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* led_classdev_resume - resume an led_classdev.
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* @led_cdev: the led_classdev to resume.
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*/
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void led_classdev_resume(struct led_classdev *led_cdev)
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{
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led_set_brightness_nopm(led_cdev, led_cdev->brightness);
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if (led_cdev->flash_resume)
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led_cdev->flash_resume(led_cdev);
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led_cdev->flags &= ~LED_SUSPENDED;
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}
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EXPORT_SYMBOL_GPL(led_classdev_resume);
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#ifdef CONFIG_PM_SLEEP
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static int led_suspend(struct device *dev)
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{
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
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led_classdev_suspend(led_cdev);
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return 0;
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}
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static int led_resume(struct device *dev)
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{
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
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led_classdev_resume(led_cdev);
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return 0;
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}
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#endif
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static SIMPLE_DEV_PM_OPS(leds_class_dev_pm_ops, led_suspend, led_resume);
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static int match_name(struct device *dev, const void *data)
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{
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if (!dev_name(dev))
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return 0;
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return !strcmp(dev_name(dev), (char *)data);
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}
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static int led_classdev_next_name(const char *init_name, char *name,
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size_t len)
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{
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unsigned int i = 0;
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int ret = 0;
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struct device *dev;
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strlcpy(name, init_name, len);
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while ((ret < len) &&
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(dev = class_find_device(leds_class, NULL, name, match_name))) {
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put_device(dev);
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ret = snprintf(name, len, "%s_%u", init_name, ++i);
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}
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if (ret >= len)
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return -ENOMEM;
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return i;
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}
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/**
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* led_classdev_register - register a new object of led_classdev class.
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* @parent: The device to register.
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* @led_cdev: the led_classdev structure for this device.
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*/
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int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
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{
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char name[LED_MAX_NAME_SIZE];
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int ret;
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ret = led_classdev_next_name(led_cdev->name, name, sizeof(name));
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if (ret < 0)
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return ret;
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led_cdev->dev = device_create_with_groups(leds_class, parent, 0,
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led_cdev, led_cdev->groups, "%s", name);
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if (IS_ERR(led_cdev->dev))
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return PTR_ERR(led_cdev->dev);
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if (ret)
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dev_warn(parent, "Led %s renamed to %s due to name collision",
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led_cdev->name, dev_name(led_cdev->dev));
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if (led_cdev->flags & LED_BRIGHT_HW_CHANGED) {
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ret = led_add_brightness_hw_changed(led_cdev);
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if (ret) {
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device_unregister(led_cdev->dev);
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return ret;
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}
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}
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led_cdev->work_flags = 0;
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#ifdef CONFIG_LEDS_TRIGGERS
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init_rwsem(&led_cdev->trigger_lock);
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#endif
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#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
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led_cdev->brightness_hw_changed = -1;
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#endif
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mutex_init(&led_cdev->led_access);
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/* add to the list of leds */
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down_write(&leds_list_lock);
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list_add_tail(&led_cdev->node, &leds_list);
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up_write(&leds_list_lock);
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if (!led_cdev->max_brightness)
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led_cdev->max_brightness = LED_FULL;
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led_update_brightness(led_cdev);
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led_init_core(led_cdev);
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#ifdef CONFIG_LEDS_TRIGGERS
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led_trigger_set_default(led_cdev);
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#endif
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dev_dbg(parent, "Registered led device: %s\n",
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led_cdev->name);
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return 0;
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}
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EXPORT_SYMBOL_GPL(led_classdev_register);
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/**
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* led_classdev_unregister - unregisters a object of led_properties class.
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* @led_cdev: the led device to unregister
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*
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* Unregisters a previously registered via led_classdev_register object.
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*/
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void led_classdev_unregister(struct led_classdev *led_cdev)
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{
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#ifdef CONFIG_LEDS_TRIGGERS
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down_write(&led_cdev->trigger_lock);
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if (led_cdev->trigger)
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led_trigger_set(led_cdev, NULL);
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up_write(&led_cdev->trigger_lock);
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#endif
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led_cdev->flags |= LED_UNREGISTERING;
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/* Stop blinking */
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led_stop_software_blink(led_cdev);
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led_set_brightness(led_cdev, LED_OFF);
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flush_work(&led_cdev->set_brightness_work);
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if (led_cdev->flags & LED_BRIGHT_HW_CHANGED)
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led_remove_brightness_hw_changed(led_cdev);
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device_unregister(led_cdev->dev);
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down_write(&leds_list_lock);
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list_del(&led_cdev->node);
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up_write(&leds_list_lock);
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mutex_destroy(&led_cdev->led_access);
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}
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EXPORT_SYMBOL_GPL(led_classdev_unregister);
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static void devm_led_classdev_release(struct device *dev, void *res)
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{
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led_classdev_unregister(*(struct led_classdev **)res);
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}
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/**
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* devm_led_classdev_register - resource managed led_classdev_register()
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* @parent: The device to register.
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* @led_cdev: the led_classdev structure for this device.
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*/
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int devm_led_classdev_register(struct device *parent,
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struct led_classdev *led_cdev)
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{
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struct led_classdev **dr;
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int rc;
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dr = devres_alloc(devm_led_classdev_release, sizeof(*dr), GFP_KERNEL);
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if (!dr)
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return -ENOMEM;
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rc = led_classdev_register(parent, led_cdev);
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if (rc) {
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devres_free(dr);
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return rc;
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}
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*dr = led_cdev;
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devres_add(parent, dr);
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return 0;
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}
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EXPORT_SYMBOL_GPL(devm_led_classdev_register);
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static int devm_led_classdev_match(struct device *dev, void *res, void *data)
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{
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struct led_cdev **p = res;
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if (WARN_ON(!p || !*p))
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return 0;
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return *p == data;
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}
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/**
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* devm_led_classdev_unregister() - resource managed led_classdev_unregister()
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* @parent: The device to unregister.
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* @led_cdev: the led_classdev structure for this device.
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*/
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void devm_led_classdev_unregister(struct device *dev,
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struct led_classdev *led_cdev)
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{
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WARN_ON(devres_release(dev,
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devm_led_classdev_release,
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devm_led_classdev_match, led_cdev));
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}
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EXPORT_SYMBOL_GPL(devm_led_classdev_unregister);
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static int __init leds_init(void)
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{
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leds_class = class_create(THIS_MODULE, "leds");
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if (IS_ERR(leds_class))
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return PTR_ERR(leds_class);
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leds_class->pm = &leds_class_dev_pm_ops;
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leds_class->dev_groups = led_groups;
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return 0;
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}
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static void __exit leds_exit(void)
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{
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class_destroy(leds_class);
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}
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subsys_initcall(leds_init);
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module_exit(leds_exit);
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MODULE_AUTHOR("John Lenz, Richard Purdie");
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("LED Class Interface");
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