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Date: Wed, 11 Jul 2018 19:02:38 +0800
From: Baolin Wang <baolin.wang@...aro.org>
To: Jacek Anaszewski <jacek.anaszewski@...il.com>,
Pavel Machek <pavel@....cz>
Cc: Bjorn Andersson <bjorn.andersson@...aro.org>,
Baolin Wang <baolin.wang@...aro.org>,
Mark Brown <broonie@...nel.org>,
Linux LED Subsystem <linux-leds@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/2] leds: core: Introduce generic pattern interface
Hi Jacek and Pavel,
On 29 June 2018 at 13:03, Baolin Wang <baolin.wang@...aro.org> wrote:
> From: Bjorn Andersson <bjorn.andersson@...aro.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 minor improvements.]
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
> ---
> 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.
> ---
Do you have any comments for this version patch set? Thanks.
> Documentation/ABI/testing/sysfs-class-led | 17 +++++
> drivers/leds/led-class.c | 119 +++++++++++++++++++++++++++++
> include/linux/leds.h | 19 +++++
> 3 files changed, 155 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led
> index 5f67f7a..e01ac55 100644
> --- a/Documentation/ABI/testing/sysfs-class-led
> +++ b/Documentation/ABI/testing/sysfs-class-led
> @@ -61,3 +61,20 @@ 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: June 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.
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index 3c7e348..8a685a2 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -74,6 +74,123 @@ 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;
> +
> + if (!led_cdev->pattern_get)
> + return -EOPNOTSUPP;
> +
> + 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;
> + unsigned long val;
> + char *sbegin;
> + char *elem;
> + char *s;
> + int ret, 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) {
> + ret = led_cdev->pattern_clear(led_cdev);
> + 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 +205,13 @@ 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[] = {
> 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 */
> --
> 1.7.9.5
>
--
Baolin Wang
Best Regards
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