linux/drivers/leds/led-triggers.c
Johannes Berg 5ada28bf76 led-class: always implement blinking
Currently, blinking LEDs can be awkward because it is not guaranteed that
all LEDs implement blinking.  The trigger that wants it to blink then
needs to implement its own timer solution.

Rather than require that, add led_blink_set() API that triggers can use.
This function will attempt to use hw blinking, but if that fails
implements a timer for it.  To stop blinking again, brightness_set() also
needs to be wrapped into API that will stop the software blink.

As a result of this, the timer trigger becomes a very trivial one, and
hopefully we can finally see triggers using blinking as well because it's
always easy to use.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Richard Purdie <rpurdie@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-11-12 07:55:32 -08:00

265 lines
6.8 KiB
C

/*
* LED Triggers Core
*
* Copyright 2005-2007 Openedhand Ltd.
*
* Author: Richard Purdie <rpurdie@openedhand.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#include <linux/sysdev.h>
#include <linux/timer.h>
#include <linux/rwsem.h>
#include <linux/leds.h>
#include <linux/slab.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 */
ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct led_classdev *led_cdev = dev_get_drvdata(dev);
char trigger_name[TRIG_NAME_MAX];
struct led_trigger *trig;
size_t len;
trigger_name[sizeof(trigger_name) - 1] = '\0';
strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
len = strlen(trigger_name);
if (len && trigger_name[len - 1] == '\n')
trigger_name[len - 1] = '\0';
if (!strcmp(trigger_name, "none")) {
led_trigger_remove(led_cdev);
return count;
}
down_read(&triggers_list_lock);
list_for_each_entry(trig, &trigger_list, next_trig) {
if (!strcmp(trigger_name, trig->name)) {
down_write(&led_cdev->trigger_lock);
led_trigger_set(led_cdev, trig);
up_write(&led_cdev->trigger_lock);
up_read(&triggers_list_lock);
return count;
}
}
up_read(&triggers_list_lock);
return -EINVAL;
}
EXPORT_SYMBOL_GPL(led_trigger_store);
ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct led_classdev *led_cdev = dev_get_drvdata(dev);
struct led_trigger *trig;
int len = 0;
down_read(&triggers_list_lock);
down_read(&led_cdev->trigger_lock);
if (!led_cdev->trigger)
len += sprintf(buf+len, "[none] ");
else
len += sprintf(buf+len, "none ");
list_for_each_entry(trig, &trigger_list, next_trig) {
if (led_cdev->trigger && !strcmp(led_cdev->trigger->name,
trig->name))
len += sprintf(buf+len, "[%s] ", trig->name);
else
len += sprintf(buf+len, "%s ", trig->name);
}
up_read(&led_cdev->trigger_lock);
up_read(&triggers_list_lock);
len += sprintf(len+buf, "\n");
return len;
}
EXPORT_SYMBOL_GPL(led_trigger_show);
/* Caller must ensure led_cdev->trigger_lock held */
void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trigger)
{
unsigned long flags;
/* Remove any existing trigger */
if (led_cdev->trigger) {
write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
list_del(&led_cdev->trig_list);
write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
flags);
if (led_cdev->trigger->deactivate)
led_cdev->trigger->deactivate(led_cdev);
led_cdev->trigger = NULL;
led_brightness_set(led_cdev, LED_OFF);
}
if (trigger) {
write_lock_irqsave(&trigger->leddev_list_lock, flags);
list_add_tail(&led_cdev->trig_list, &trigger->led_cdevs);
write_unlock_irqrestore(&trigger->leddev_list_lock, flags);
led_cdev->trigger = trigger;
if (trigger->activate)
trigger->activate(led_cdev);
}
}
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);
void led_trigger_set_default(struct led_classdev *led_cdev)
{
struct led_trigger *trig;
if (!led_cdev->default_trigger)
return;
down_read(&triggers_list_lock);
down_write(&led_cdev->trigger_lock);
list_for_each_entry(trig, &trigger_list, next_trig) {
if (!strcmp(led_cdev->default_trigger, trig->name))
led_trigger_set(led_cdev, trig);
}
up_write(&led_cdev->trigger_lock);
up_read(&triggers_list_lock);
}
EXPORT_SYMBOL_GPL(led_trigger_set_default);
/* LED Trigger Interface */
int led_trigger_register(struct led_trigger *trigger)
{
struct led_classdev *led_cdev;
struct led_trigger *trig;
rwlock_init(&trigger->leddev_list_lock);
INIT_LIST_HEAD(&trigger->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, trigger->name)) {
up_write(&triggers_list_lock);
return -EEXIST;
}
}
/* Add to the list of led triggers */
list_add_tail(&trigger->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 &&
!strcmp(led_cdev->default_trigger, trigger->name))
led_trigger_set(led_cdev, trigger);
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 *trigger)
{
struct led_classdev *led_cdev;
/* Remove from the list of led triggers */
down_write(&triggers_list_lock);
list_del(&trigger->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 == trigger)
led_trigger_set(led_cdev, NULL);
up_write(&led_cdev->trigger_lock);
}
up_read(&leds_list_lock);
}
EXPORT_SYMBOL_GPL(led_trigger_unregister);
/* Simple LED Tigger Interface */
void led_trigger_event(struct led_trigger *trigger,
enum led_brightness brightness)
{
struct list_head *entry;
if (!trigger)
return;
read_lock(&trigger->leddev_list_lock);
list_for_each(entry, &trigger->led_cdevs) {
struct led_classdev *led_cdev;
led_cdev = list_entry(entry, struct led_classdev, trig_list);
led_set_brightness(led_cdev, brightness);
}
read_unlock(&trigger->leddev_list_lock);
}
EXPORT_SYMBOL_GPL(led_trigger_event);
void led_trigger_register_simple(const char *name, struct led_trigger **tp)
{
struct led_trigger *trigger;
int err;
trigger = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
if (trigger) {
trigger->name = name;
err = led_trigger_register(trigger);
if (err < 0)
printk(KERN_WARNING "LED trigger %s failed to register"
" (%d)\n", name, err);
} else
printk(KERN_WARNING "LED trigger %s failed to register"
" (no memory)\n", name);
*tp = trigger;
}
EXPORT_SYMBOL_GPL(led_trigger_register_simple);
void led_trigger_unregister_simple(struct led_trigger *trigger)
{
if (trigger)
led_trigger_unregister(trigger);
kfree(trigger);
}
EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
MODULE_AUTHOR("Richard Purdie");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LED Triggers Core");