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SubjectRe: [PATCH v15 1/2] leds: core: Introduce LED pattern trigger
Hi,

On 12 October 2018 at 04:07, Jacek Anaszewski
<jacek.anaszewski@gmail.com> wrote:
> Hi Baolin,
>
> On 10/11/2018 06:07 AM, Baolin Wang wrote:
>> This patch adds a new led trigger that LED device can 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>
>> ---
>> Changes from v14:
>> - Improve the commit message and ABI documentation.
>> - Fix some coding style issues.
>> - Do not limit the tuple's duration larger than 50 ms, and treat is
>> as a a step change of brightness.
>>
>> Changes from v13:
>> - Add duration validation for gradual dimming.
>> - Coding style optimization.
>>
>> Changes from v12:
>> - Add gradual dimming support for software pattern.
>>
>> Changes from v11:
>> - Change -1 means repeat indefinitely.
>>
>> Changes from v10:
>> - Change 'int' to 'u32' for delta_t field.
>>
>> Changes from v9:
>> - None.
>>
>> Changes from v8:
>> - None.
>>
>> Changes from v7:
>> - Move the SC27XX hardware patterns description into its own ABI file.
>>
>> Changes from v6:
>> - Improve commit message.
>> - Optimize the description of the hw_pattern file.
>> - Simplify some logics.
>>
>> Changes from v5:
>> - Add one 'hw_pattern' file for hardware patterns.
>>
>> Changes from v4:
>> - Change the repeat file to return the originally written number.
>> - Improve comments.
>> - Fix some build warnings.
>>
>> Changes from v3:
>> - Reset pattern number to 0 if user provides incorrect pattern string.
>> - Support one pattern.
>>
>> Changes from v2:
>> - Remove hardware_pattern boolen.
>> - Chnage the pattern string format.
>>
>> Changes from v1:
>> - Use ATTRIBUTE_GROUPS() to define attributes.
>> - Introduce hardware_pattern flag to determine if software pattern
>> or hardware pattern.
>> - Re-implement pattern_trig_store_pattern() function.
>> - Remove pattern_get() interface.
>> - Improve comments.
>> - Other small optimization.
>> ---
>> .../ABI/testing/sysfs-class-led-trigger-pattern | 82 ++++
>> drivers/leds/trigger/Kconfig | 7 +
>> drivers/leds/trigger/Makefile | 1 +
>> drivers/leds/trigger/ledtrig-pattern.c | 411 ++++++++++++++++++++
>> include/linux/leds.h | 15 +
>> 5 files changed, 516 insertions(+)
>> create mode 100644 Documentation/ABI/testing/sysfs-class-led-trigger-pattern
>> create mode 100644 drivers/leds/trigger/ledtrig-pattern.c
>>
>> diff --git a/Documentation/ABI/testing/sysfs-class-led-trigger-pattern b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
>> new file mode 100644
>> index 0000000..fb3d1e0
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
>> @@ -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.
>> diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig
>> index 4018af7..b76fc3c 100644
>> --- a/drivers/leds/trigger/Kconfig
>> +++ b/drivers/leds/trigger/Kconfig
>> @@ -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
>> diff --git a/drivers/leds/trigger/Makefile b/drivers/leds/trigger/Makefile
>> index f3cfe19..9bcb64e 100644
>> --- a/drivers/leds/trigger/Makefile
>> +++ b/drivers/leds/trigger/Makefile
>> @@ -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
>> diff --git a/drivers/leds/trigger/ledtrig-pattern.c b/drivers/leds/trigger/ledtrig-pattern.c
>> new file mode 100644
>> index 0000000..ce7acd1
>> --- /dev/null
>> +++ b/drivers/leds/trigger/ledtrig-pattern.c
>> @@ -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");
>> diff --git a/include/linux/leds.h b/include/linux/leds.h
>> index 834683d..7393a31 100644
>> --- a/include/linux/leds.h
>> +++ b/include/linux/leds.h
>> @@ -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 */
>>
>
> OK, let's abide by constant update interval for now.
>
> Thank you for your work on this patch set throughout
> all these months. We will have -rc8, so one week of testing
> before sending upstream should be enough.
>
> Patch set applied to the for-next branch of linux-leds.git.

Thanks Jacek and Pavel, you are so patient and always give me lots of
help there. Glad to co-work with you, thanks again.

--
Baolin Wang
Best Regards

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