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Date: Mon, 16 Feb 2009 14:57:46 +0200
From: Felipe Balbi <felipe.balbi@...ia.com>
To: "Balbi Felipe (Nokia-D/Helsinki)" <felipe.balbi@...ia.com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Felipe Balbi <me@...ipebalbi.com>,
Richard Purdie <rpurdie@...ys.net>
Subject: Re: [PATCH] leds: triggers: introduce gpio led trigger
On Mon, Feb 16, 2009 at 01:17:31PM +0100, Balbi Felipe (Nokia-D/Helsinki) wrote:
> From: Felipe Balbi <me@...ipebalbi.com>
>
> The gpio led trigger will allow leds to be triggered by
> gpio events.
>
> There's a timer function that keeps checking the gpio
> value in order to know when we need to turn leds on/off.
>
> It's useful for usecases as n810's keypad leds that could
> be triggered by the gpio event generated when user slides
> up to show the keypad.
>
> We also provide means for userland to tell us what is the
> desired brightness for that special led when it goes on
> so userland could use information from ambient light sensors
> and not set led brightness too high if it's not necessary.
>
> This trigger was tested with n810.
>
> Cc: Richard Purdie <rpurdie@...ys.net>
> Signed-off-by: Felipe Balbi <me@...ipebalbi.com>
> ---
> drivers/leds/Kconfig | 13 +++
> drivers/leds/Makefile | 1 +
> drivers/leds/ledtrig-gpio.c | 229 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 243 insertions(+), 0 deletions(-)
> create mode 100644 drivers/leds/ledtrig-gpio.c
>
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 7427136..2bd77d5 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -216,6 +216,19 @@ config LEDS_TRIGGER_BACKLIGHT
>
> If unsure, say N.
>
> +config LEDS_TRIGGER_GPIO
> + tristate "LED GPIO Trigger"
> + depends on LEDS_TRIGGERS
> + depends on GPIOLIB
> + help
> + This allows LEDs to be controlled by gpio events. It's good
> + when using gpios as switches and triggering the needed LEDs
> + from there. One use case is n810's keypad LEDs that could
> + be triggered by this trigger when user slides up to show
> + keypad.
> +
> + If unsure, say N.
> +
> config LEDS_TRIGGER_DEFAULT_ON
> tristate "LED Default ON Trigger"
> depends on LEDS_TRIGGERS
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 9d76f0f..c9e5d31 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -30,4 +30,5 @@ obj-$(CONFIG_LEDS_TRIGGER_TIMER) += ledtrig-timer.o
> obj-$(CONFIG_LEDS_TRIGGER_IDE_DISK) += ledtrig-ide-disk.o
> obj-$(CONFIG_LEDS_TRIGGER_HEARTBEAT) += ledtrig-heartbeat.o
> obj-$(CONFIG_LEDS_TRIGGER_BACKLIGHT) += ledtrig-backlight.o
> +obj-$(CONFIG_LEDS_TRIGGER_GPIO) += ledtrig-gpio.o
> obj-$(CONFIG_LEDS_TRIGGER_DEFAULT_ON) += ledtrig-default-on.o
> diff --git a/drivers/leds/ledtrig-gpio.c b/drivers/leds/ledtrig-gpio.c
> new file mode 100644
> index 0000000..af24dcf
> --- /dev/null
> +++ b/drivers/leds/ledtrig-gpio.c
> @@ -0,0 +1,229 @@
> +/*
> + * ledtrig-gio.c - LED Trigger Based on GPIO events
> + *
> + * Copyright 2009 Felipe Balbi <me@...ipebalbi.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/gpio.h>
> +#include <linux/workqueue.h>
> +#include <linux/leds.h>
> +#include "leds.h"
> +
> +struct gpio_trig_data {
> + struct delayed_work work;
> + struct led_classdev *led;
> +
> + unsigned desired_brightness; /* desired brightness when led is on */
> + unsigned inverted; /* true when gpio is inverted */
> + unsigned gpio; /* gpio that triggers the leds */
> +};
> +
> +static ssize_t gpio_trig_brightness_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct led_classdev *led = dev_get_drvdata(dev);
> + struct gpio_trig_data *gpio_data = led->trigger_data;
> +
> + return sprintf(buf, "%u\n", gpio_data->desired_brightness);
> +}
> +
> +static ssize_t gpio_trig_brightness_store(struct device *dev,
> + struct device_attribute *attr, const char *buf, size_t n)
> +{
> + struct led_classdev *led = dev_get_drvdata(dev);
> + struct gpio_trig_data *gpio_data = led->trigger_data;
> + unsigned desired_brightness;
> + int ret;
> +
> + ret = sscanf(buf, "%u", &desired_brightness);
> + if (ret < 1 || desired_brightness > 255) {
> + dev_err(dev, "invalid value\n");
> + return -EINVAL;
> + }
> +
> + gpio_data->desired_brightness = desired_brightness;
> +
> + return n;
> +}
> +static DEVICE_ATTR(desired_brightness, 0644, gpio_trig_brightness_show,
> + gpio_trig_brightness_store);
> +
> +static ssize_t gpio_trig_inverted_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct led_classdev *led = dev_get_drvdata(dev);
> + struct gpio_trig_data *gpio_data = led->trigger_data;
> +
> + return sprintf(buf, "%s\n", gpio_data->inverted ? "yes" : "no");
> +}
> +
> +static ssize_t gpio_trig_inverted_store(struct device *dev,
> + struct device_attribute *attr, const char *buf, size_t n)
> +{
> + struct led_classdev *led = dev_get_drvdata(dev);
> + struct gpio_trig_data *gpio_data = led->trigger_data;
> + unsigned inverted;
> + int ret;
> +
> + ret = sscanf(buf, "%u", &inverted);
> + if (ret < 1) {
> + dev_err(dev, "invalid value\n");
> + return -EINVAL;
> + }
> +
> + gpio_data->inverted = !!inverted;
> +
> + return n;
> +}
> +static DEVICE_ATTR(inverted, 0644, gpio_trig_inverted_show,
> + gpio_trig_inverted_store);
> +
> +static ssize_t gpio_trig_gpio_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct led_classdev *led = dev_get_drvdata(dev);
> + struct gpio_trig_data *gpio_data = led->trigger_data;
> +
> + return sprintf(buf, "%u\n", gpio_data->gpio);
> +}
> +
> +static ssize_t gpio_trig_gpio_store(struct device *dev,
> + struct device_attribute *attr, const char *buf, size_t n)
> +{
> + struct led_classdev *led = dev_get_drvdata(dev);
> + struct gpio_trig_data *gpio_data = led->trigger_data;
> + unsigned gpio;
> + int ret;
> +
> + ret = sscanf(buf, "%u", &gpio);
> + if (ret < 1) {
> + dev_err(dev, "couldn't read gpio number\n");
> + cancel_delayed_work(&gpio_data->work);
> + return -EINVAL;
> + }
> +
> + gpio_data->gpio = gpio;
> + schedule_delayed_work(&gpio_data->work, msecs_to_jiffies(50));
> +
> + return n;
> +}
> +static DEVICE_ATTR(gpio, 0644, gpio_trig_gpio_show, gpio_trig_gpio_store);
> +
> +static void gpio_trig_work(struct work_struct *work)
> +{
> + struct gpio_trig_data *gpio_data = container_of(work,
> + struct gpio_trig_data, work.work);
> +
> + if (!gpio_data->gpio)
> + goto out;
> +
> + if (!gpio_data->inverted) {
> + if (gpio_get_value(gpio_data->gpio)) {
> + if (gpio_data->desired_brightness)
> + led_set_brightness(gpio_data->led,
> + gpio_data->desired_brightness);
> + else
> + led_set_brightness(gpio_data->led, LED_FULL);
> + } else {
> + led_set_brightness(gpio_data->led, LED_OFF);
> + }
> + } else {
> + if (!gpio_get_value(gpio_data->gpio)) {
> + if (gpio_data->desired_brightness)
> + led_set_brightness(gpio_data->led,
> + gpio_data->desired_brightness);
> + else
> + led_set_brightness(gpio_data->led, LED_FULL);
> + } else {
> + led_set_brightness(gpio_data->led, LED_OFF);
> + }
> + }
> +
> +out:
> + /* Completely arbitrary constant. I'm guessing user won't be able
> + * to trigger gpio event twice in less then 50ms and in case of
> + * having to trigger several leds, we won't notice the delay between
> + * them.
> + */
> + schedule_delayed_work(&gpio_data->work, msecs_to_jiffies(50));
> +}
> +
> +static void gpio_trig_activate(struct led_classdev *led)
> +{
> + struct gpio_trig_data *gpio_data;
> + int ret;
> +
> + gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
> + if (!gpio_data)
> + return;
> +
> + ret = device_create_file(led->dev, &dev_attr_gpio);
> + if (ret)
> + goto err_gpio;
> +
> + ret = device_create_file(led->dev, &dev_attr_inverted);
> + if (ret)
> + goto err_inverted;
> +
> + ret = device_create_file(led->dev, &dev_attr_desired_brightness);
> + if (ret)
> + goto err_brightness;
> +
> + gpio_data->led = led;
> + led->trigger_data = gpio_data;
> + INIT_DELAYED_WORK(&gpio_data->work, gpio_trig_work);
> +
> + return;
> +
> +err_brightness:
> + device_remove_file(led->dev, &dev_attr_inverted);
> +
> +err_inverted:
> + device_remove_file(led->dev, &dev_attr_gpio);
> +
> +err_gpio:
> + kfree(gpio_data);
> +}
> +
> +static void gpio_trig_deactivate(struct led_classdev *led)
> +{
> + struct gpio_trig_data *gpio_data = led->trigger_data;
> +
> + if (gpio_data) {
> + device_remove_file(led->dev, &dev_attr_gpio);
> + device_remove_file(led->dev, &dev_attr_inverted);
> + device_remove_file(led->dev, &dev_attr_desired_brightness);
> + cancel_delayed_work(&gpio_data->work);
Just a question. Should I flush_scheduled_work() here ??
Here goes a patch adding it:
diff --git a/drivers/leds/ledtrig-gpio.c b/drivers/leds/ledtrig-gpio.c
index af24dcf..d532812 100644
--- a/drivers/leds/ledtrig-gpio.c
+++ b/drivers/leds/ledtrig-gpio.c
@@ -202,6 +202,7 @@ static void gpio_trig_deactivate(struct led_classdev *led)
device_remove_file(led->dev, &dev_attr_inverted);
device_remove_file(led->dev, &dev_attr_desired_brightness);
cancel_delayed_work(&gpio_data->work);
+ flush_scheduled_work();
kfree(gpio_data);
}
}
--
balbi
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