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// SPDX-License-Identifier: GPL-2.0
/*
* LED pattern trigger
*
* Idea discussed with Pavel Machek. Raphael Teysseyre implemented
* the first version, Baolin Wang simplified and improved the approach.
*/
#include <linux/kernel.h>
#include <linux/leds.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/timer.h>
#define MAX_PATTERNS 1024
/*
* When doing gradual dimming, the led brightness will be updated
* every 50 milliseconds.
*/
#define UPDATE_INTERVAL 50
struct pattern_trig_data {
struct led_classdev *led_cdev;
struct led_pattern patterns[MAX_PATTERNS];
struct led_pattern *curr;
struct led_pattern *next;
struct mutex lock;
u32 npatterns;
int repeat;
int last_repeat;
int delta_t;
bool is_indefinite;
bool is_hw_pattern;
struct timer_list timer;
};
static void pattern_trig_update_patterns(struct pattern_trig_data *data)
{
data->curr = data->next;
if (!data->is_indefinite && data->curr == data->patterns)
data->repeat--;
if (data->next == data->patterns + data->npatterns - 1)
data->next = data->patterns;
else
data->next++;
data->delta_t = 0;
}
static int pattern_trig_compute_brightness(struct pattern_trig_data *data)
{
int step_brightness;
/*
* If current tuple's duration is less than the dimming interval,
* we should treat it as a step change of brightness instead of
* doing gradual dimming.
*/
if (data->delta_t == 0 || data->curr->delta_t < UPDATE_INTERVAL)
return data->curr->brightness;
step_brightness = abs(data->next->brightness - data->curr->brightness);
step_brightness = data->delta_t * step_brightness / data->curr->delta_t;
if (data->next->brightness > data->curr->brightness)
return data->curr->brightness + step_brightness;
else
return data->curr->brightness - step_brightness;
}
static void pattern_trig_timer_function(struct timer_list *t)
{
struct pattern_trig_data *data = from_timer(data, t, timer);
mutex_lock(&data->lock);
for (;;) {
if (!data->is_indefinite && !data->repeat)
break;
if (data->curr->brightness == data->next->brightness) {
/* Step change of brightness */
led_set_brightness(data->led_cdev,
data->curr->brightness);
mod_timer(&data->timer,
jiffies + msecs_to_jiffies(data->curr->delta_t));
if (!data->next->delta_t) {
/* Skip the tuple with zero duration */
pattern_trig_update_patterns(data);
}
/* Select next tuple */
pattern_trig_update_patterns(data);
} else {
/* Gradual dimming */
/*
* If the accumulation time is larger than current
* tuple's duration, we should go next one and re-check
* if we repeated done.
*/
if (data->delta_t > data->curr->delta_t) {
pattern_trig_update_patterns(data);
continue;
}
led_set_brightness(data->led_cdev,
pattern_trig_compute_brightness(data));
mod_timer(&data->timer,
jiffies + msecs_to_jiffies(UPDATE_INTERVAL));
/* Accumulate the gradual dimming time */
data->delta_t += UPDATE_INTERVAL;
}
break;
}
mutex_unlock(&data->lock);
}
static int pattern_trig_start_pattern(struct led_classdev *led_cdev)
{
struct pattern_trig_data *data = led_cdev->trigger_data;
if (!data->npatterns)
return 0;
if (data->is_hw_pattern) {
return led_cdev->pattern_set(led_cdev, data->patterns,
data->npatterns, data->repeat);
}
/* At least 2 tuples for software pattern. */
if (data->npatterns < 2)
return -EINVAL;
data->delta_t = 0;
data->curr = data->patterns;
data->next = data->patterns + 1;
data->timer.expires = jiffies;
add_timer(&data->timer);
return 0;
}
static ssize_t repeat_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct led_classdev *led_cdev = dev_get_drvdata(dev);
struct pattern_trig_data *data = led_cdev->trigger_data;
int repeat;
mutex_lock(&data->lock);
repeat = data->last_repeat;
mutex_unlock(&data->lock);
return scnprintf(buf, PAGE_SIZE, "%d\n", repeat);
}
static ssize_t repeat_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct led_classdev *led_cdev = dev_get_drvdata(dev);
struct pattern_trig_data *data = led_cdev->trigger_data;
int err, res;
err = kstrtos32(buf, 10, &res);
if (err)
return err;
/* Number 0 and negative numbers except -1 are invalid. */
if (res < -1 || res == 0)
return -EINVAL;
/*
* Clear previous patterns' performence firstly, and remove the timer
* without mutex lock to avoid dead lock.
*/
del_timer_sync(&data->timer);
mutex_lock(&data->lock);
if (data->is_hw_pattern)
led_cdev->pattern_clear(led_cdev);
data->last_repeat = data->repeat = res;
/* -1 means repeat indefinitely */
if (data->repeat == -1)
data->is_indefinite = true;
else
data->is_indefinite = false;
err = pattern_trig_start_pattern(led_cdev);
mutex_unlock(&data->lock);
return err < 0 ? err : count;
}
static DEVICE_ATTR_RW(repeat);
static ssize_t pattern_trig_show_patterns(struct pattern_trig_data *data,
char *buf, bool hw_pattern)
{
ssize_t count = 0;
int i;
mutex_lock(&data->lock);
if (!data->npatterns || (data->is_hw_pattern ^ hw_pattern))
goto out;
for (i = 0; i < data->npatterns; i++) {
count += scnprintf(buf + count, PAGE_SIZE - count,
"%d %u ",
data->patterns[i].brightness,
data->patterns[i].delta_t);
}
buf[count - 1] = '\n';
out:
mutex_unlock(&data->lock);
return count;
}
static ssize_t pattern_trig_store_patterns(struct led_classdev *led_cdev,
const char *buf, size_t count,
bool hw_pattern)
{
struct pattern_trig_data *data = led_cdev->trigger_data;
int ccount, cr, offset = 0, err = 0;
/*
* Clear previous patterns' performence firstly, and remove the timer
* without mutex lock to avoid dead lock.
*/
del_timer_sync(&data->timer);
mutex_lock(&data->lock);
if (data->is_hw_pattern)
led_cdev->pattern_clear(led_cdev);
data->is_hw_pattern = hw_pattern;
data->npatterns = 0;
while (offset < count - 1 && data->npatterns < MAX_PATTERNS) {
cr = 0;
ccount = sscanf(buf + offset, "%d %u %n",
&data->patterns[data->npatterns].brightness,
&data->patterns[data->npatterns].delta_t, &cr);
if (ccount != 2) {
data->npatterns = 0;
err = -EINVAL;
goto out;
}
offset += cr;
data->npatterns++;
}
err = pattern_trig_start_pattern(led_cdev);
if (err)
data->npatterns = 0;
out:
mutex_unlock(&data->lock);
return err < 0 ? err : count;
}
static ssize_t pattern_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct led_classdev *led_cdev = dev_get_drvdata(dev);
struct pattern_trig_data *data = led_cdev->trigger_data;
return pattern_trig_show_patterns(data, buf, false);
}
static ssize_t pattern_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct led_classdev *led_cdev = dev_get_drvdata(dev);
return pattern_trig_store_patterns(led_cdev, buf, count, false);
}
static DEVICE_ATTR_RW(pattern);
static ssize_t hw_pattern_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct led_classdev *led_cdev = dev_get_drvdata(dev);
struct pattern_trig_data *data = led_cdev->trigger_data;
return pattern_trig_show_patterns(data, buf, true);
}
static ssize_t hw_pattern_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct led_classdev *led_cdev = dev_get_drvdata(dev);
return pattern_trig_store_patterns(led_cdev, buf, count, true);
}
static DEVICE_ATTR_RW(hw_pattern);
static umode_t pattern_trig_attrs_mode(struct kobject *kobj,
struct attribute *attr, int index)
{
struct device *dev = container_of(kobj, struct device, kobj);
struct led_classdev *led_cdev = dev_get_drvdata(dev);
if (attr == &dev_attr_repeat.attr || attr == &dev_attr_pattern.attr)
return attr->mode;
else if (attr == &dev_attr_hw_pattern.attr && led_cdev->pattern_set)
return attr->mode;
return 0;
}
static struct attribute *pattern_trig_attrs[] = {
&dev_attr_pattern.attr,
&dev_attr_hw_pattern.attr,
&dev_attr_repeat.attr,
NULL
};
static const struct attribute_group pattern_trig_group = {
.attrs = pattern_trig_attrs,
.is_visible = pattern_trig_attrs_mode,
};
static const struct attribute_group *pattern_trig_groups[] = {
&pattern_trig_group,
NULL,
};
static int pattern_trig_activate(struct led_classdev *led_cdev)
{
struct pattern_trig_data *data;
data = kzalloc(sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
if (!!led_cdev->pattern_set ^ !!led_cdev->pattern_clear) {
dev_warn(led_cdev->dev,
"Hardware pattern ops validation failed\n");
led_cdev->pattern_set = NULL;
led_cdev->pattern_clear = NULL;
}
data->is_indefinite = true;
data->last_repeat = -1;
mutex_init(&data->lock);
data->led_cdev = led_cdev;
led_set_trigger_data(led_cdev, data);
timer_setup(&data->timer, pattern_trig_timer_function, 0);
led_cdev->activated = true;
return 0;
}
static void pattern_trig_deactivate(struct led_classdev *led_cdev)
{
struct pattern_trig_data *data = led_cdev->trigger_data;
if (!led_cdev->activated)
return;
if (led_cdev->pattern_clear)
led_cdev->pattern_clear(led_cdev);
del_timer_sync(&data->timer);
led_set_brightness(led_cdev, LED_OFF);
kfree(data);
led_cdev->activated = false;
}
static struct led_trigger pattern_led_trigger = {
.name = "pattern",
.activate = pattern_trig_activate,
.deactivate = pattern_trig_deactivate,
.groups = pattern_trig_groups,
};
static int __init pattern_trig_init(void)
{
return led_trigger_register(&pattern_led_trigger);
}
static void __exit pattern_trig_exit(void)
{
led_trigger_unregister(&pattern_led_trigger);
}
module_init(pattern_trig_init);
module_exit(pattern_trig_exit);
MODULE_AUTHOR("Raphael Teysseyre <rteysseyre@gmail.com");
MODULE_AUTHOR("Baolin Wang <baolin.wang@linaro.org");
MODULE_DESCRIPTION("LED Pattern trigger");
MODULE_LICENSE("GPL v2");
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