Re: [PATCH v4 1/2] leds: core: Introduce LED pattern trigger

Jacek Anaszewski
2018-08-05T16:11:01Z

Hi Baolin,

Thank you for the fix.

I've found few more details to improve, please take a look
at my comments below.

On 08/05/2018 06:04 AM, 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@gmail.com>
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> ---
> 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 | 21 ++
> drivers/leds/trigger/Kconfig | 7 +
> drivers/leds/trigger/Makefile | 1 +
> drivers/leds/trigger/ledtrig-pattern.c | 271 +++++++++++++++++++++
> include/linux/leds.h | 16 ++
> 5 files changed, 316 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..40afefe
> --- /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.

In current implementation this file on read returns the number
of remaining repeat intervals. I'd add that to this description.

> 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..e5b90b7
> --- /dev/null
> +++ b/drivers/leds/trigger/ledtrig-pattern.c
> @@ -0,0 +1,271 @@
> +// 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
> +
> +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;
> + 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_set) {
> + return led_cdev->pattern_set(led_cdev, data->patterns,
> + data->npatterns, data->repeat);
> + }
> +
> + data->curr = data->patterns;
> + data->next = data->npatterns > 1 ? data->patterns + 1 : data->patterns;
> + 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)

Please fix checkpatch.pl warnings:

WARNING: Consider renaming function(s) 'pattern_trig_show_repeat' to
'repeat_show' 'pattern_trig_store_repeat' to 'repeat_store'
#209: FILE: drivers/leds/trigger/ledtrig-pattern.c:127:
+}

WARNING: Consider renaming function(s) 'pattern_trig_show_pattern' to
'pattern_show' 'pattern_trig_store_pattern' to 'pattern_store'
#276: FILE: drivers/leds/trigger/ledtrig-pattern.c:194:
+}

> +{
> + struct led_classdev *led_cdev = dev_get_drvdata(dev);
> + struct pattern_trig_data *data = led_cdev->trigger_data;
> + u32 repeat;
> +
> + mutex_lock(&data->lock);
> +
> + 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;
> +
> + if (!led_cdev->pattern_set)
> + del_timer_sync(&data->timer);

Is there a reason for not having this check under mutex?

> + 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);
> +
> + mutex_unlock(&data->lock);
> + return err < 0 ? err : 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 i;
> +
> + mutex_lock(&data->lock);
> +
> + if (!data->npatterns)
> + goto out;
> +
> + for (i = 0; i < data->npatterns; i++) {
> + count += scnprintf(buf + count, PAGE_SIZE - count,
> + "%d %d ",
> + 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_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 ccount, cr, offset = 0, err = 0;
> +
> + if (!led_cdev->pattern_set)
> + del_timer_sync(&data->timer);

Ditto.

> + mutex_lock(&data->lock);
> +
> + data->npatterns = 0;
> + while (offset < count - 1 && data->npatterns < MAX_PATTERNS) {
> + cr = 0;
> + ccount = sscanf(buf + offset, "%d %d %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(data, led_cdev);
> +
> +out:
> + mutex_unlock(&data->lock);
> + return err < 0 ? err : count;
> +}
> +
> +static DEVICE_ATTR(pattern, 0644, pattern_trig_show_pattern,
> + pattern_trig_store_pattern);
> +
> +static struct attribute *pattern_trig_attrs[] = {
> + &dev_attr_pattern.attr,
> + &dev_attr_repeat.attr,
> + NULL
> +};
> +ATTRIBUTE_GROUPS(pattern_trig);
> +
> +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;
> + 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);
> + else
> + 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..c54712c 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 +89,11 @@ 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_clear)(struct led_classdev *led_cdev);
> +
> struct device *dev;
> const struct attribute_group **groups;
>
> @@ -472,4 +478,14 @@ 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

Since this structure describes single pattern interval and not
the whole pattern, please change its description to:

pattern interval settings

> + * @delta_t: delay until next entry, in milliseconds

@delta_t: pattern interval delay, in milliseconds

> + * @brightness: brightness at time = 0

@brightness: pattern interval brightness

> + */
> +struct led_pattern {
> + int delta_t;
> + int brightness;
> +};
> +
> #endif /* __LINUX_LEDS_H_INCLUDED */
>

--
Best regards,
Jacek Anaszewski