Hi Jacek,
On 14 July 2018 at 04:07, Jacek Anaszewski <jacek.anaszew...@gmail.com> wrote:
> Hi Baolin,
>
> Thank you for the update.
>
>
> On 07/13/2018 08:21 AM, Baolin Wang wrote:
>>
>> From: Bjorn Andersson <bjorn.anders...@linaro.org>
>>
>> Some LED controllers have support for autonomously controlling
>> brightness over time, according to some preprogrammed pattern or
>> function.
>>
>> This adds a new optional operator that LED class drivers can implement
>> if they support such functionality as well as a new device attribute to
>> configure the pattern for a given LED.
>>
>> [Baolin Wang did some improvements.]
>>
>> Signed-off-by: Bjorn Andersson <bjorn.anders...@linaro.org>
>> Signed-off-by: Baolin Wang <baolin.w...@linaro.org>
>> ---
>> Changes from v3:
>> - Move the check in pattern_show() to of_led_classdev_register().
>> - Add more documentation to explain how to set/clear one pattern.
>>
>> Changes from v2:
>> - Change kernel version to 4.19.
>> - Force user to return error pointer if failed to issue pattern_get().
>> - Use strstrip() to trim trailing newline.
>> - Other optimization.
>>
>> Changes from v1:
>> - Add some comments suggested by Pavel.
>> - Change 'delta_t' can be 0.
>>
>> Note: I removed the pattern repeat check and will get the repeat number by
>> adding
>> one extra file named 'pattern_repeat' according to previous discussion.
>> ---
>> Documentation/ABI/testing/sysfs-class-led | 20 +++++
>> drivers/leds/led-class.c | 118
>> +++++++++++++++++++++++++++++
>> include/linux/leds.h | 19 +++++
>> 3 files changed, 157 insertions(+)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-class-led
>> b/Documentation/ABI/testing/sysfs-class-led
>> index 5f67f7a..f4b73ad 100644
>> --- a/Documentation/ABI/testing/sysfs-class-led
>> +++ b/Documentation/ABI/testing/sysfs-class-led
>> @@ -61,3 +61,23 @@ Description:
>> gpio and backlight triggers. In case of the backlight
>> trigger,
>> it is useful when driving a LED which is intended to
>> indicate
>> a device in a standby like state.
>> +
>> +What: /sys/class/leds/<led>/pattern
>> +Date: July 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.
>> +
>> + As LED hardware might have different capabilities and
>> precision
>> + the requested pattern might be slighly adjusted by the
>> driver
>> + and the resulting pattern of such operation should be
>> returned
>> + when this file is read.
>> +
>> + Writing non-empty string to this file will active the
>> pattern,
>
>
> s/active/activate/
Will fix the typo.
>
>
>> + and empty string will disable the pattern.
>> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
>> index 3c7e348..0992a0e 100644
>> --- a/drivers/leds/led-class.c
>> +++ b/drivers/leds/led-class.c
>> @@ -74,6 +74,119 @@ static ssize_t max_brightness_show(struct device *dev,
>> }
>> static DEVICE_ATTR_RO(max_brightness);
>> +static ssize_t pattern_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + struct led_classdev *led_cdev = dev_get_drvdata(dev);
>> + struct led_pattern *pattern;
>> + size_t offset = 0;
>> + int count, n, i;
>> +
>> + pattern = led_cdev->pattern_get(led_cdev, &count);
>> + if (IS_ERR(pattern))
>> + return PTR_ERR(pattern);
>> +
>> + for (i = 0; i < count; i++) {
>> + n = snprintf(buf + offset, PAGE_SIZE - offset, "%d %d ",
>> + pattern[i].brightness, pattern[i].delta_t);
>> +
>> + if (offset + n >= PAGE_SIZE)
>> + goto err_nospc;
>> +
>> + offset += n;
>> + }
>> +
>> + buf[offset - 1] = '\n';
>> +
>> + kfree(pattern);
>> + return offset;
>> +
>> +err_nospc:
>> + kfree(pattern);
>> + return -ENOSPC;
>> +}
>> +
>> +static ssize_t pattern_store(struct device *dev,
>> + struct device_attribute *attr,
>> + const char *buf, size_t size)
>> +{
>> + struct led_classdev *led_cdev = dev_get_drvdata(dev);
>> + struct led_pattern *pattern = NULL;
>> + char *sbegin, *elem, *s;
>> + unsigned long val;
>> + int ret = 0, len = 0;
>> + bool odd = true;
>> +
>> + sbegin = kstrndup(buf, size, GFP_KERNEL);
>> + if (!sbegin)
>> + return -ENOMEM;
>> +
>> + /*
>> + * Trim trailing newline, if the remaining string is empty,
>> + * clear the pattern.
>> + */
>> + s = strstrip(sbegin);
>> + if (!*s) {
>> + if (led_cdev->pattern_clear)
>> + ret = led_cdev->pattern_clear(led_cdev);
>
>
> Why you don't require pattern_clear op to be initialized?
> Without it there seems to be no other way to disable the pattern.
>
> Please fail in led_classdev_register() if it is NULL, similarly
> as when pattern_get is NULL.
Ah, I misunderstood your previous comments. Yes, we can ceck it in
led_classdev_register().
>
>
>> + goto out;
>> + }
>> +
>> + pattern = kcalloc(size, sizeof(*pattern), GFP_KERNEL);
>> + if (!pattern) {
>> + ret = -ENOMEM;
>> + goto out;
>> + }
>> +
>> + /* Parse out the brightness & delta_t touples */
>> + while ((elem = strsep(&s, " ")) != NULL) {
>> + ret = kstrtoul(elem, 10, &val);
>> + if (ret)
>> + goto out;
>> +
>> + if (odd) {
>> + pattern[len].brightness = val;
>> + } else {
>> + pattern[len].delta_t = val;
>> + len++;
>> + }
>> +
>> + odd = !odd;
>> + }
>> +
>> + /*
>> + * Fail if we didn't find any data points or last data point was
>> partial
>> + */
>> + if (!len || !odd) {
>> + ret = -EINVAL;
>> + goto out;
>> + }
>> +
>> + ret = led_cdev->pattern_set(led_cdev, pattern, len);
>> +
>> +out:
>> + kfree(pattern);
>> + kfree(sbegin);
>> + return ret < 0 ? ret : size;
>> +}
>> +static DEVICE_ATTR_RW(pattern);
>> +
>> +static umode_t led_class_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_brightness.attr)
>> + return attr->mode;
>> + if (attr == &dev_attr_max_brightness.attr)
>> + return attr->mode;
>> + if (attr == &dev_attr_pattern.attr && led_cdev->pattern_set)
>> + return attr->mode;
>> +
>> + return 0;
>> +}
>> +
>> #ifdef CONFIG_LEDS_TRIGGERS
>> static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
>> static struct attribute *led_trigger_attrs[] = {
>> @@ -88,11 +201,13 @@ static ssize_t max_brightness_show(struct device
>> *dev,
>> static struct attribute *led_class_attrs[] = {
>> &dev_attr_brightness.attr,
>> &dev_attr_max_brightness.attr,
>> + &dev_attr_pattern.attr,
>> NULL,
>> };
>> static const struct attribute_group led_group = {
>> .attrs = led_class_attrs,
>> + .is_visible = led_class_attrs_mode,
>> };
>> static const struct attribute_group *led_groups[] = {
>> @@ -256,6 +371,9 @@ int of_led_classdev_register(struct device *parent,
>> struct device_node *np,
>> char name[LED_MAX_NAME_SIZE];
>> int ret;
>> + if (led_cdev->pattern_set && !led_cdev->pattern_get)
>
>
> if (led_cdev->pattern_set && (!led_cdev->pattern_get ||
> !led_cdev->pattern_clear)
Sure. Thanks for your help.
>
>
>> + return -EINVAL;
>> +
>> ret = led_classdev_next_name(led_cdev->name, name, sizeof(name));
>> if (ret < 0)
>> return ret;
>> diff --git a/include/linux/leds.h b/include/linux/leds.h
>> index b7e8255..acdbb2f 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);
>> +
>> + int (*pattern_clear)(struct led_classdev *led_cdev);
>> +
>> + struct led_pattern *(*pattern_get)(struct led_classdev *led_cdev,
>> + int *len);
>> +
>> 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 - brigheness 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
--
Baolin Wang
Best Regards
