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SubjectRe: [PATCH v15 1/2] leds: core: Introduce LED pattern trigger
From
Date
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.

--
Best regards,
Jacek Anaszewski

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