Re: [PATCH 1/2] leds: core: Introduce LED pattern trigger

From: Jacek Anaszewski
Date: Tue Jul 31 2018 - 06:53:58 EST

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Hi Baolin,

Thank you for the patch set. I have one note regarding the way how
trigger specific sysfs attributes are created/removed, please refer
to my comment in the code below.

On 07/30/2018 02:29 PM, Baolin Wang wrote:
> Some LED controllers have support for autonomously controlling
> brightness over time, according to some preprogrammed pattern or
> function.
>
> This patch adds pattern trigger that LED device can configure the
> pattern and trigger it.
>
> Signed-off-by: Raphael Teysseyre <rteysseyre@xxxxxxxxx>
> Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
> ---
> .../ABI/testing/sysfs-class-led-trigger-pattern | 21 ++
> drivers/leds/trigger/Kconfig | 10 +
> drivers/leds/trigger/Makefile | 1 +
> drivers/leds/trigger/ledtrig-pattern.c | 349 ++++++++++++++++++++
> include/linux/leds.h | 19 ++
> 5 files changed, 400 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..c52da34
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
> @@ -0,0 +1,21 @@
> +What: /sys/class/leds/<led>/pattern
> +Date: August 2018
> +KernelVersion: 4.19
> +Description:
> + Specify a pattern for the LED, for LED hardware that support
> + altering the brightness as a function of time.
> +
> + 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.
> +
> + The format of the pattern values should be:
> + "brightness_1 duration_1, brightness_2 duration_2, brightness_3
> + duration_3, ...".
> +
> +What: /sys/class/leds/<led>/repeat
> +Date: August 2018
> +KernelVersion: 4.19
> +Description:
> + Specify a pattern repeat number. 0 means repeat indefinitely.
> diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig
> index a2559b4..a03afcd 100644
> --- a/drivers/leds/trigger/Kconfig
> +++ b/drivers/leds/trigger/Kconfig
> @@ -125,6 +125,16 @@ config LEDS_TRIGGER_CAMERA
> This enables direct flash/torch on/off by the driver, kernel space.
> If unsure, say Y.
>
> +config LEDS_TRIGGER_PATTERN
> + tristate "LED Pattern Trigger"
> + depends on LEDS_TRIGGERS
> + help
> + This allows LEDs blinking with an arbitrary pattern. Can be useful
> + on embedded systems with no screen to give out a status code to
> + a human.
> +
> + If unsure, say N
> +
> config LEDS_TRIGGER_PANIC
> bool "LED Panic Trigger"
> depends on LEDS_TRIGGERS
> diff --git a/drivers/leds/trigger/Makefile b/drivers/leds/trigger/Makefile
> index f3cfe19..c5d180e 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..b709aa1
> --- /dev/null
> +++ b/drivers/leds/trigger/ledtrig-pattern.c
> @@ -0,0 +1,349 @@
> +// 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>
> +
> +/*
> + * The "pattern" attribute contains at most PAGE_SIZE characters. Each line
> + * in this attribute is at least 4 characters long (a 1-digit number for the
> + * led brighntess, a space, a 1-digit number for the time, a semi-colon).
> + * Therefore, there is at most PAGE_SIZE/4 patterns.
> + */
> +#define MAX_PATTERNS (PAGE_SIZE / 4)
> +#define PATTERN_SEPARATOR ","
> +
> +struct pattern_trig_data {
> + struct led_classdev *led_cdev;
> + struct led_pattern *patterns;
> + struct led_pattern *curr;
> + struct led_pattern *next;
> + struct mutex lock;
> + u32 npatterns;
> + u32 repeat;
> + bool is_indefinite;
> + 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++;
> +}
> +
> +static void pattern_trig_timer_function(struct timer_list *t)
> +{
> + struct pattern_trig_data *data = from_timer(data, t, timer);
> +
> + mutex_lock(&data->lock);
> +
> + if (!data->is_indefinite && !data->repeat) {
> + mutex_unlock(&data->lock);
> + return;
> + }
> +
> + led_set_brightness(data->led_cdev, data->curr->brightness);
> + mod_timer(&data->timer, jiffies + msecs_to_jiffies(data->curr->delta_t));
> + pattern_trig_update_patterns(data);
> +
> + mutex_unlock(&data->lock);
> +}
> +
> +static int pattern_trig_start_pattern(struct pattern_trig_data *data,
> + struct led_classdev *led_cdev)
> +{
> + if (!data->npatterns)
> + return 0;
> +
> + if (led_cdev->pattern_clear)
> + led_cdev->pattern_clear(led_cdev);
> +
> + if (led_cdev->pattern_set) {
> + return led_cdev->pattern_set(led_cdev, data->patterns,
> + data->npatterns, data->repeat);
> + }
> +
> + data->curr = data->patterns;
> + data->next = data->patterns + 1;
> + data->timer.expires = jiffies;
> + add_timer(&data->timer);
> +
> + return 0;
> +}
> +
> +static ssize_t pattern_trig_show_repeat(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 err;
> + u32 repeat;
> +
> + mutex_lock(&data->lock);
> +
> + if (led_cdev->pattern_get) {
> + err = led_cdev->pattern_get(led_cdev, data->patterns,
> + &data->npatterns, &data->repeat);
> + if (err) {
> + mutex_unlock(&data->lock);
> + return err;
> + }
> + }
> +
> + repeat = data->repeat;
> + mutex_unlock(&data->lock);
> +
> + return scnprintf(buf, PAGE_SIZE, "%u\n", repeat);
> +}
> +
> +static ssize_t pattern_trig_store_repeat(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;
> + unsigned long res;
> + int err;
> +
> + err = kstrtoul(buf, 10, &res);
> + if (err)
> + return err;
> +
> + del_timer_sync(&data->timer);
> +
> + mutex_lock(&data->lock);
> + data->repeat = res;
> +
> + /* 0 means repeat indefinitely */
> + if (!data->repeat)
> + data->is_indefinite = true;
> + else
> + data->is_indefinite = false;
> +
> + err = pattern_trig_start_pattern(data, led_cdev);
> + if (err) {
> + mutex_unlock(&data->lock);
> + return err;
> + }
> +
> + mutex_unlock(&data->lock);
> + return count;
> +}
> +
> +static DEVICE_ATTR(repeat, 0644, pattern_trig_show_repeat,
> + pattern_trig_store_repeat);
> +
> +static ssize_t pattern_trig_show_pattern(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;
> + ssize_t count = 0;
> + int err, i;
> +
> + mutex_lock(&data->lock);
> +
> + if (led_cdev->pattern_get) {
> + err = led_cdev->pattern_get(led_cdev, data->patterns,
> + &data->npatterns, &data->repeat);
> + if (err) {
> + mutex_unlock(&data->lock);
> + return err;
> + }
> + }
> +
> + if (!data->npatterns) {
> + mutex_unlock(&data->lock);
> + return -EINVAL;
> + }
> +
> + for (i = 0; i < data->npatterns; i++) {
> + count += scnprintf(buf + count, PAGE_SIZE - count,
> + "%d %d" PATTERN_SEPARATOR,
> + data->patterns[i].brightness,
> + data->patterns[i].delta_t);
> + }
> +
> + buf[count - 1] = '\n';
> + buf[count] = '\0';
> +
> + mutex_unlock(&data->lock);
> + return count + 1;
> +}
> +
> +static ssize_t pattern_trig_store_pattern(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, cr, ccount, tcr = 0;
> +
> + del_timer_sync(&data->timer);
> +
> + mutex_lock(&data->lock);
> +
> + for (data->npatterns = 0; data->npatterns < MAX_PATTERNS;
> + data->npatterns++) {
> + /* Characters read on one conversion */
> + cr = 0;
> + /* Number of successful conversions */
> + ccount = sscanf(buf + tcr, "%d %d " PATTERN_SEPARATOR "%n",
> + &data->patterns[data->npatterns].brightness,
> + &data->patterns[data->npatterns].delta_t, &cr);
> +
> + /* Total characters read */
> + tcr += cr;
> + if (cr)
> + continue;
> +
> + /* Invalid syntax or end of pattern */
> + if (ccount == 2)
> + data->npatterns++;
> +
> + err = pattern_trig_start_pattern(data, led_cdev);
> + if (err) {
> + mutex_unlock(&data->lock);
> + return err;
> + }
> +
> + mutex_unlock(&data->lock);
> + return count;
> + }
> +
> + /* Shouldn't reach that */
> + WARN(1, "MAX_NSTEP too small. Please report\n");
> + mutex_unlock(&data->lock);
> + return count;
> +}
> +
> +static DEVICE_ATTR(pattern, 0644, pattern_trig_show_pattern,
> + pattern_trig_store_pattern);
> +
> +static int pattern_trig_create_sysfs_files(struct device *dev)
> +{
> + int err;
> +
> + err = device_create_file(dev, &dev_attr_repeat);
> + if (err)
> + return err;
> +
> + err = device_create_file(dev, &dev_attr_pattern);
> + if (err)
> + device_remove_file(dev, &dev_attr_repeat);

We've recently merged patch set of Uwe Kleine-KÃnig that adds
groups attribute to the struct led_trigger, and updates all
triggers to use it. Please follow the new approach - refer to
linux-next or directly to
https://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds.git/log/?h=for-next.

> + return err;
> +}
> +
> +static void pattern_trig_remove_sysfs_files(struct device *dev)
> +{
> + device_remove_file(dev, &dev_attr_pattern);
> + device_remove_file(dev, &dev_attr_repeat);
> +}
> +
> +static int pattern_trig_initialize_data(struct pattern_trig_data *data)
> +{
> + data->patterns = kcalloc(MAX_PATTERNS, sizeof(struct led_pattern),
> + GFP_KERNEL);
> + if (!data->patterns)
> + return -ENOMEM;
> +
> + data->is_indefinite = true;
> + mutex_init(&data->lock);
> +
> + return 0;
> +}
> +
> +static void pattern_trig_clear_data(struct pattern_trig_data *data)
> +{
> + kfree(data->patterns);
> +}
> +
> +static void pattern_trig_activate(struct led_classdev *led_cdev)
> +{
> + struct pattern_trig_data *data;
> + int err;
> +
> + data = kzalloc(sizeof(*data), GFP_KERNEL);
> + if (!data)
> + return;
> +
> + err = pattern_trig_initialize_data(data);
> + if (err) {
> + kfree(data);
> + return;
> + }
> +
> + err = pattern_trig_create_sysfs_files(led_cdev->dev);
> + if (err) {
> + pattern_trig_clear_data(data);
> + kfree(data);
> + return;
> + }
> +
> + data->led_cdev = led_cdev;
> + led_cdev->trigger_data = data;
> + timer_setup(&data->timer, pattern_trig_timer_function, 0);
> + led_cdev->activated = true;
> +}
> +
> +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);
> + pattern_trig_remove_sysfs_files(led_cdev->dev);
> + led_set_brightness(led_cdev, LED_OFF);
> + pattern_trig_clear_data(data);
> + kfree(data);
> + led_cdev->trigger_data = NULL;
> + led_cdev->activated = false;
> +}
> +
> +static struct led_trigger pattern_led_trigger = {
> + .name = "pattern",
> + .activate = pattern_trig_activate,
> + .deactivate = pattern_trig_deactivate,
> +};
> +
> +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@xxxxxxxxx");
> +MODULE_AUTHOR("Baolin Wang <baolin.wang@xxxxxxxxxx");
> +MODULE_DESCRIPTION("LED Pattern trigger");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index b7e8255..bea02f0 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 +89,14 @@ struct led_classdev {
> unsigned long *delay_on,
> unsigned long *delay_off);
>
> + int (*pattern_set)(struct led_classdev *led_cdev,
> + struct led_pattern *pattern, int len,
> + unsigned repeat);
> + int (*pattern_get)(struct led_classdev *led_cdev,
> + struct led_pattern *pattern, int *len,
> + unsigned *repeat);
> + int (*pattern_clear)(struct led_classdev *led_cdev);
> +
> struct device *dev;
> const struct attribute_group **groups;
>
> @@ -446,4 +455,14 @@ static inline void led_classdev_notify_brightness_hw_changed(
> struct led_classdev *led_cdev, enum led_brightness brightness) { }
> #endif
>
> +/**
> + * struct led_pattern - brightness value in a pattern
> + * @delta_t: delay until next entry, in milliseconds
> + * @brightness: brightness at time = 0
> + */
> +struct led_pattern {
> + int delta_t;
> + int brightness;
> +};
> +
> #endif /* __LINUX_LEDS_H_INCLUDED */
>

--
Best regards,
Jacek Anaszewski

Next message: Peter Zijlstra: "Re: [PATCH 0/4] sched/topology: Set SD_ASYM_CPUCAPACITY flag automatically"
Previous message: Aaron Ma: "[PATCH] ACPI / EC: Use ec_no_wakeup on ThinkPad X1 Yoga 3rd"
In reply to: Baolin Wang: "Re: [PATCH 1/2] leds: core: Introduce LED pattern trigger"
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