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leds: core: Introduce LED pattern trigger 

This patch adds a new LED trigger that LED device can configure
to employ software or hardware pattern engine.

Consumers can write 'pattern' file to enable the software pattern
which alters the brightness for the specified duration with one
software timer.

Moreover consumers can write 'hw_pattern' file to enable the hardware
pattern for some LED controllers which can autonomously control
brightness over time, according to some preprogrammed hardware
patterns.

Signed-off-by: Raphael Teysseyre <rteysseyre@gmail.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
hifive-unleashed-5.1
Baolin Wang 2018-10-11 12:07:14 +08:00 committed by Jacek Anaszewski
parent 2d00f35c55
commit 5fd752b6b3
5 changed files with 516 additions and 0 deletions
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82
Documentation/ABI/testing/sysfs-class-led-trigger-pattern 100644
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@ -0,0 +1,82 @@
What: /sys/class/leds/<led>/pattern
Date: September 2018
KernelVersion: 4.20
Description:
Specify a software pattern for the LED, that supports altering
the brightness for the specified duration with one software
timer. It can do gradual dimming and step change of brightness.
The pattern is given by a series of tuples, of brightness and
duration (ms). The LED is expected to traverse the series and
each brightness value for the specified duration. Duration of
0 means brightness should immediately change to new value, and
writing malformed pattern deactivates any active one.
1. For gradual dimming, the dimming interval now is set as 50
milliseconds. So the tuple with duration less than dimming
interval (50ms) is treated as a step change of brightness,
i.e. the subsequent brightness will be applied without adding
intervening dimming intervals.
The gradual dimming format of the software pattern values should be:
"brightness_1 duration_1 brightness_2 duration_2 brightness_3
duration_3 ...". For example:
echo 0 1000 255 2000 > pattern
It will make the LED go gradually from zero-intensity to max (255)
intensity in 1000 milliseconds, then back to zero intensity in 2000
milliseconds:
LED brightness
^
255-| / \ / \ /
| / \ / \ /
| / \ / \ /
| / \ / \ /
0-| / \/ \/
+---0----1----2----3----4----5----6------------> time (s)
2. To make the LED go instantly from one brigntess value to another,
we should use use zero-time lengths (the brightness must be same as
the previous tuple's). So the format should be:
"brightness_1 duration_1 brightness_1 0 brightness_2 duration_2
brightness_2 0 ...". For example:
echo 0 1000 0 0 255 2000 255 0 > pattern
It will make the LED stay off for one second, then stay at max brightness
for two seconds:
LED brightness
^
255-| +---------+ +---------+
| | | | |
| | | | |
| | | | |
0-| -----+ +----+ +----
+---0----1----2----3----4----5----6------------> time (s)
What: /sys/class/leds/<led>/hw_pattern
Date: September 2018
KernelVersion: 4.20
Description:
Specify a hardware pattern for the LED, for LED hardware that
supports autonomously controlling brightness over time, according
to some preprogrammed hardware patterns. It deactivates any active
software pattern.
Since different LED hardware can have different semantics of
hardware patterns, each driver is expected to provide its own
description for the hardware patterns in their ABI documentation
file.
What: /sys/class/leds/<led>/repeat
Date: September 2018
KernelVersion: 4.20
Description:
Specify a pattern repeat number. -1 means repeat indefinitely,
other negative numbers and number 0 are invalid.
This file will always return the originally written repeat
number.

7
drivers/leds/trigger/Kconfig
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@ -129,4 +129,11 @@ config LEDS_TRIGGER_NETDEV
This allows LEDs to be controlled by network device activity.
If unsure, say Y.
config LEDS_TRIGGER_PATTERN
tristate "LED Pattern Trigger"
help
This allows LEDs to be controlled by a software or hardware pattern
which is a series of tuples, of brightness and duration (ms).
If unsure, say N
endif # LEDS_TRIGGERS

1
drivers/leds/trigger/Makefile
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@ -13,3 +13,4 @@ obj-$(CONFIG_LEDS_TRIGGER_TRANSIENT) += ledtrig-transient.o
obj-$(CONFIG_LEDS_TRIGGER_CAMERA) += ledtrig-camera.o
obj-$(CONFIG_LEDS_TRIGGER_PANIC) += ledtrig-panic.o
obj-$(CONFIG_LEDS_TRIGGER_NETDEV) += ledtrig-netdev.o
obj-$(CONFIG_LEDS_TRIGGER_PATTERN) += ledtrig-pattern.o

411
drivers/leds/trigger/ledtrig-pattern.c 100644
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@ -0,0 +1,411 @@
// 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));
/* 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");

15
include/linux/leds.h
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@ -22,6 +22,7 @@
#include <linux/workqueue.h>
struct device;
struct led_pattern;
/*
* LED Core
*/
@ -88,6 +89,10 @@ struct led_classdev {
unsigned long *delay_on,
unsigned long *delay_off);
int (*pattern_set)(struct led_classdev *led_cdev,
struct led_pattern *pattern, u32 len, int repeat);
int (*pattern_clear)(struct led_classdev *led_cdev);
struct device *dev;
const struct attribute_group **groups;
@ -472,4 +477,14 @@ static inline void led_classdev_notify_brightness_hw_changed(
struct led_classdev *led_cdev, enum led_brightness brightness) { }
#endif
/**
* struct led_pattern - pattern interval settings
* @delta_t: pattern interval delay, in milliseconds
* @brightness: pattern interval brightness
*/
struct led_pattern {
u32 delta_t;
int brightness;
};
#endif /* __LINUX_LEDS_H_INCLUDED */