Quellcode-Bibliothek led-triggers.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
 * LED Triggers Core
 *
 * Copyright 2005-2007 Openedhand Ltd.
 *
 * Author: Richard Purdie <rpurdie@openedhand.com>
 */

#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#include <linux/timer.h>
#include <linux/rwsem.h>
#include <linux/leds.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include "leds.h"

/*
 * Nests outside led_cdev->trigger_lock
 */
static DECLARE_RWSEM(triggers_list_lock);
static LIST_HEAD(trigger_list);

 /* Used by LED Class */

static inline bool
trigger_relevant(struct led_classdev *led_cdev, struct led_trigger *trig)
{
 return !trig->trigger_type || trig->trigger_type == led_cdev->trigger_type;
}

ssize_t led_trigger_write(struct file *filp, struct kobject *kobj,
     const struct bin_attribute *bin_attr, char *buf,
     loff_t pos, size_t count)
{
 struct device *dev = kobj_to_dev(kobj);
 struct led_classdev *led_cdev = dev_get_drvdata(dev);
 struct led_trigger *trig;
 int ret = count;

 mutex_lock(&led_cdev->led_access);

 if (led_sysfs_is_disabled(led_cdev)) {
  ret = -EBUSY;
  goto unlock;
 }

 if (sysfs_streq(buf, "none")) {
  led_trigger_remove(led_cdev);
  goto unlock;
 }

 if (sysfs_streq(buf, "default")) {
  led_trigger_set_default(led_cdev);
  goto unlock;
 }

 down_read(&triggers_list_lock);
 list_for_each_entry(trig, &trigger_list, next_trig) {
  if (sysfs_streq(buf, trig->name) && trigger_relevant(led_cdev, trig)) {
   down_write(&led_cdev->trigger_lock);
   led_trigger_set(led_cdev, trig);
   up_write(&led_cdev->trigger_lock);

   up_read(&triggers_list_lock);
   goto unlock;
  }
 }
 /* we come here only if buf matches no trigger */
 ret = -EINVAL;
 up_read(&triggers_list_lock);

unlock:
 mutex_unlock(&led_cdev->led_access);
 return ret;
}
EXPORT_SYMBOL_GPL(led_trigger_write);

__printf(3, 4)
static int led_trigger_snprintf(char *buf, ssize_t size, const char *fmt, ...)
{
 va_list args;
 int i;

 va_start(args, fmt);
 if (size <= 0)
  i = vsnprintf(NULL, 0, fmt, args);
 else
  i = vscnprintf(buf, size, fmt, args);
 va_end(args);

 return i;
}

static int led_trigger_format(char *buf, size_t size,
         struct led_classdev *led_cdev)
{
 struct led_trigger *trig;
 int len = led_trigger_snprintf(buf, size, "%s",
           led_cdev->trigger ? "none" : "[none]");

 if (led_cdev->default_trigger)
  len += led_trigger_snprintf(buf + len, size - len, " default");

 list_for_each_entry(trig, &trigger_list, next_trig) {
  bool hit;

  if (!trigger_relevant(led_cdev, trig))
   continue;

  hit = led_cdev->trigger && !strcmp(led_cdev->trigger->name, trig->name);

  len += led_trigger_snprintf(buf + len, size - len,
         " %s%s%s", hit ? "[" : "",
         trig->name, hit ? "]" : "");
 }

 len += led_trigger_snprintf(buf + len, size - len, "\n");

 return len;
}

/*
 * It was stupid to create 10000 cpu triggers, but we are stuck with it now.
 * Don't make that mistake again. We work around it here by creating binary
 * attribute, which is not limited by length. This is _not_ good design, do not
 * copy it.
 */
ssize_t led_trigger_read(struct file *filp, struct kobject *kobj,
   const struct bin_attribute *attr, char *buf,
   loff_t pos, size_t count)
{
 struct device *dev = kobj_to_dev(kobj);
 struct led_classdev *led_cdev = dev_get_drvdata(dev);
 void *data;
 int len;

 down_read(&triggers_list_lock);
 down_read(&led_cdev->trigger_lock);

 len = led_trigger_format(NULL, 0, led_cdev);
 data = kvmalloc(len + 1, GFP_KERNEL);
 if (!data) {
  up_read(&led_cdev->trigger_lock);
  up_read(&triggers_list_lock);
  return -ENOMEM;
 }
 len = led_trigger_format(data, len + 1, led_cdev);

 up_read(&led_cdev->trigger_lock);
 up_read(&triggers_list_lock);

 len = memory_read_from_buffer(buf, count, &pos, data, len);

 kvfree(data);

 return len;
}
EXPORT_SYMBOL_GPL(led_trigger_read);

/* Caller must ensure led_cdev->trigger_lock held */
int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
{
 char *event = NULL;
 char *envp[2];
 const char *name;
 int ret;

 if (!led_cdev->trigger && !trig)
  return 0;

 name = trig ? trig->name : "none";
 event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);

 /* Remove any existing trigger */
 if (led_cdev->trigger) {
  spin_lock(&led_cdev->trigger->leddev_list_lock);
  list_del_rcu(&led_cdev->trig_list);
  spin_unlock(&led_cdev->trigger->leddev_list_lock);

  /* ensure it's no longer visible on the led_cdevs list */
  synchronize_rcu();

  cancel_work_sync(&led_cdev->set_brightness_work);
  led_stop_software_blink(led_cdev);
  device_remove_groups(led_cdev->dev, led_cdev->trigger->groups);
  if (led_cdev->trigger->deactivate)
   led_cdev->trigger->deactivate(led_cdev);
  led_cdev->trigger = NULL;
  led_cdev->trigger_data = NULL;
  led_cdev->activated = false;
  led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER;
  led_set_brightness(led_cdev, LED_OFF);
 }
 if (trig) {
  spin_lock(&trig->leddev_list_lock);
  list_add_tail_rcu(&led_cdev->trig_list, &trig->led_cdevs);
  spin_unlock(&trig->leddev_list_lock);
  led_cdev->trigger = trig;

  /*
 * Some activate() calls use led_trigger_event() to initialize
 * the brightness of the LED for which the trigger is being set.
 * Ensure the led_cdev is visible on trig->led_cdevs for this.
 */
  synchronize_rcu();

  /*
 * If "set brightness to 0" is pending in workqueue,
 * we don't want that to be reordered after ->activate()
 */
  flush_work(&led_cdev->set_brightness_work);

  ret = 0;
  if (trig->activate)
   ret = trig->activate(led_cdev);
  else
   led_set_brightness(led_cdev, trig->brightness);
  if (ret)
   goto err_activate;

  ret = device_add_groups(led_cdev->dev, trig->groups);
  if (ret) {
   dev_err(led_cdev->dev, "Failed to add trigger attributes\n");
   goto err_add_groups;
  }
 }

 if (event) {
  envp[0] = event;
  envp[1] = NULL;
  if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
   dev_err(led_cdev->dev,
    "%s: Error sending uevent\n", __func__);
  kfree(event);
 }

 return 0;

err_add_groups:

 if (trig->deactivate)
  trig->deactivate(led_cdev);
err_activate:

 spin_lock(&led_cdev->trigger->leddev_list_lock);
 list_del_rcu(&led_cdev->trig_list);
 spin_unlock(&led_cdev->trigger->leddev_list_lock);
 synchronize_rcu();
 led_cdev->trigger = NULL;
 led_cdev->trigger_data = NULL;
 led_set_brightness(led_cdev, LED_OFF);
 kfree(event);

 return ret;
}
EXPORT_SYMBOL_GPL(led_trigger_set);

void led_trigger_remove(struct led_classdev *led_cdev)
{
 down_write(&led_cdev->trigger_lock);
 led_trigger_set(led_cdev, NULL);
 up_write(&led_cdev->trigger_lock);
}
EXPORT_SYMBOL_GPL(led_trigger_remove);

static bool led_match_default_trigger(struct led_classdev *led_cdev,
          struct led_trigger *trig)
{
 if (!strcmp(led_cdev->default_trigger, trig->name) &&
     trigger_relevant(led_cdev, trig)) {
  led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
  led_trigger_set(led_cdev, trig);
  return true;
 }

 return false;
}

void led_trigger_set_default(struct led_classdev *led_cdev)
{
 struct led_trigger *trig;
 bool found = false;

 if (!led_cdev->default_trigger)
  return;

 if (!strcmp(led_cdev->default_trigger, "none")) {
  led_trigger_remove(led_cdev);
  return;
 }

 down_read(&triggers_list_lock);
 down_write(&led_cdev->trigger_lock);
 list_for_each_entry(trig, &trigger_list, next_trig) {
  found = led_match_default_trigger(led_cdev, trig);
  if (found)
   break;
 }
 up_write(&led_cdev->trigger_lock);
 up_read(&triggers_list_lock);

 /*
 * If default trigger wasn't found, maybe trigger module isn't loaded yet.
 * Once loaded it will re-probe with all led_cdev's.
 */
 if (!found)
  request_module_nowait("ledtrig:%s", led_cdev->default_trigger);
}
EXPORT_SYMBOL_GPL(led_trigger_set_default);

/* LED Trigger Interface */

int led_trigger_register(struct led_trigger *trig)
{
 struct led_classdev *led_cdev;
 struct led_trigger *_trig;

 spin_lock_init(&trig->leddev_list_lock);
 INIT_LIST_HEAD(&trig->led_cdevs);

 down_write(&triggers_list_lock);
 /* Make sure the trigger's name isn't already in use */
 list_for_each_entry(_trig, &trigger_list, next_trig) {
  if (!strcmp(_trig->name, trig->name) &&
      (trig->trigger_type == _trig->trigger_type ||
       !trig->trigger_type || !_trig->trigger_type)) {
   up_write(&triggers_list_lock);
   return -EEXIST;
  }
 }
 /* Add to the list of led triggers */
 list_add_tail(&trig->next_trig, &trigger_list);
 up_write(&triggers_list_lock);

 /* Register with any LEDs that have this as a default trigger */
 down_read(&leds_list_lock);
 list_for_each_entry(led_cdev, &leds_list, node) {
  down_write(&led_cdev->trigger_lock);
  if (!led_cdev->trigger && led_cdev->default_trigger)
   led_match_default_trigger(led_cdev, trig);
  up_write(&led_cdev->trigger_lock);
 }
 up_read(&leds_list_lock);

 return 0;
}
EXPORT_SYMBOL_GPL(led_trigger_register);

void led_trigger_unregister(struct led_trigger *trig)
{
 struct led_classdev *led_cdev;

 if (list_empty_careful(&trig->next_trig))
  return;

 /* Remove from the list of led triggers */
 down_write(&triggers_list_lock);
 list_del_init(&trig->next_trig);
 up_write(&triggers_list_lock);

 /* Remove anyone actively using this trigger */
 down_read(&leds_list_lock);
 list_for_each_entry(led_cdev, &leds_list, node) {
  down_write(&led_cdev->trigger_lock);
  if (led_cdev->trigger == trig)
   led_trigger_set(led_cdev, NULL);
  up_write(&led_cdev->trigger_lock);
 }
 up_read(&leds_list_lock);
}
EXPORT_SYMBOL_GPL(led_trigger_unregister);

static void devm_led_trigger_release(struct device *dev, void *res)
{
 led_trigger_unregister(*(struct led_trigger **)res);
}

int devm_led_trigger_register(struct device *dev,
         struct led_trigger *trig)
{
 struct led_trigger **dr;
 int rc;

 dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
     GFP_KERNEL);
 if (!dr)
  return -ENOMEM;

 *dr = trig;

 rc = led_trigger_register(trig);
 if (rc)
  devres_free(dr);
 else
  devres_add(dev, dr);

 return rc;
}
EXPORT_SYMBOL_GPL(devm_led_trigger_register);

/* Simple LED Trigger Interface */

void led_trigger_event(struct led_trigger *trig,
   enum led_brightness brightness)
{
 struct led_classdev *led_cdev;

 if (!trig)
  return;

 trig->brightness = brightness;

 rcu_read_lock();
 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
  led_set_brightness(led_cdev, brightness);
 rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(led_trigger_event);

void led_mc_trigger_event(struct led_trigger *trig,
     unsigned int *intensity_value, unsigned int num_colors,
     enum led_brightness brightness)
{
 struct led_classdev *led_cdev;

 if (!trig)
  return;

 rcu_read_lock();
 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
  if (!(led_cdev->flags & LED_MULTI_COLOR))
   continue;

  led_mc_set_brightness(led_cdev, intensity_value, num_colors, brightness);
 }
 rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(led_mc_trigger_event);

static void led_trigger_blink_setup(struct led_trigger *trig,
        unsigned long delay_on,
        unsigned long delay_off,
        int oneshot,
        int invert)
{
 struct led_classdev *led_cdev;

 if (!trig)
  return;

 rcu_read_lock();
 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
  if (oneshot)
   led_blink_set_oneshot(led_cdev, &delay_on, &delay_off,
           invert);
  else
   led_blink_set_nosleep(led_cdev, delay_on, delay_off);
 }
 rcu_read_unlock();
}

void led_trigger_blink(struct led_trigger *trig,
         unsigned long delay_on,
         unsigned long delay_off)
{
 led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
}
EXPORT_SYMBOL_GPL(led_trigger_blink);

void led_trigger_blink_oneshot(struct led_trigger *trig,
          unsigned long delay_on,
          unsigned long delay_off,
          int invert)
{
 led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
}
EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);

void led_trigger_register_simple(const char *name, struct led_trigger **tp)
{
 struct led_trigger *trig;
 int err;

 trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);

 if (trig) {
  trig->name = name;
  err = led_trigger_register(trig);
  if (err < 0) {
   kfree(trig);
   trig = NULL;
   pr_warn("LED trigger %s failed to register (%d)\n",
    name, err);
  }
 } else {
  pr_warn("LED trigger %s failed to register (no memory)\n",
   name);
 }
 *tp = trig;
}
EXPORT_SYMBOL_GPL(led_trigger_register_simple);

void led_trigger_unregister_simple(struct led_trigger *trig)
{
 if (trig)
  led_trigger_unregister(trig);
 kfree(trig);
}
EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);