Re: [PATCH v2 1/2] led: add oneshot trigger

[Shuah Khan <shuahkhan@gmail.com>]

On Tue, 2012-06-05 at 23:38 +0200, Fabio Baltieri wrote:
> Add oneshot trigger to blink a led with configurable parameters via
> sysfs.

Fabio,

What are the use-cases for this trigger. Please see comments inline:


> 
> Signed-off-by: Fabio Baltieri <fabio.baltieri@gmail.com>
> Cc: Shuah Khan <shuahkhan@gmail.com>
> Cc: Bryan Wu <bryan.wu@canonical.com>
> ---
> Hi all,
> 
> that's my v2 of the ledtrig-oneshot trigger, with the correction suggested from
> Shuah in the original thread.  These include some unnecessary initialization
> and use of the new "activated" flag.
> 
> I've kept the name to "oneshot" as I think it suits the role of the trigger as
> example/test for the led_blink_set_oneshot function but I have expanded a bit
> the Kconfig description to better identify the trigger's usage.
> 
> About the namespace question, I think that naming the parameters delay_on and
> delay_off is ok as they have the same meaning as timer's ones (they also
> uses the same internal fields after all...).
> 
> Also, I added a default set of delay_{on,off} to 100ms on activation, so that
> the trigger starts with a valid configuration, like ledtrig-timer does.
> 
> Anything else that should be changed?
> 
> Fabio
> 
>  drivers/leds/Kconfig           |  14 +++
>  drivers/leds/Makefile          |   1 +
>  drivers/leds/ledtrig-oneshot.c | 198 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 213 insertions(+)
>  create mode 100644 drivers/leds/ledtrig-oneshot.c
> 
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 04cb8c8..1f151fb 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -443,6 +443,20 @@ config LEDS_TRIGGER_TIMER
>  
>  	  If unsure, say Y.
>  
> +config LEDS_TRIGGER_ONESHOT
> +	tristate "LED One-shot Trigger"
> +	depends on LEDS_TRIGGERS
> +	help
> +	  This allows LEDs to blink in one-shot pulses with parameters
> +	  controlled via sysfs.  It's useful to notify the user on
> +	  sporadic events, when there are no clear begin and end trap points,
> +	  or on dense events, where this blinks the LED at constant rate if
> +	  rearmed continuously.
> +
> +	  It also shows how to use the led_blink_set_oneshot() function.
> +
> +	  If unsure, say Y.
> +
>  config LEDS_TRIGGER_IDE_DISK
>  	bool "LED IDE Disk Trigger"
>  	depends on IDE_GD_ATA
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index f8958cd..9112d51 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -53,6 +53,7 @@ obj-$(CONFIG_LEDS_DAC124S085)		+= leds-dac124s085.o
>  
>  # LED Triggers
>  obj-$(CONFIG_LEDS_TRIGGER_TIMER)	+= ledtrig-timer.o
> +obj-$(CONFIG_LEDS_TRIGGER_ONESHOT)	+= ledtrig-oneshot.o
>  obj-$(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
> diff --git a/drivers/leds/ledtrig-oneshot.c b/drivers/leds/ledtrig-oneshot.c
> new file mode 100644
> index 0000000..1aacdfe
> --- /dev/null
> +++ b/drivers/leds/ledtrig-oneshot.c
> @@ -0,0 +1,198 @@
> +/*
> + * One-shot LED Trigger
> + *
> + * Copyright 2012, Fabio Baltieri <fabio.baltieri@gmail.com>
> + *
> + * Based on ledtrig-timer.c by Richard Purdie <rpurdie@openedhand.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/device.h>
> +#include <linux/ctype.h>
> +#include <linux/slab.h>
> +#include <linux/leds.h>
> +
> +#define DEFAULT_DELAY 100
> +
> +struct oneshot_trig_data {
> +	unsigned int invert;
> +};
> +
> +static ssize_t led_shot(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t size)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct oneshot_trig_data *oneshot_data = led_cdev->trigger_data;
> +
> +	led_blink_set_oneshot(led_cdev,
> +			&led_cdev->blink_delay_on, &led_cdev->blink_delay_off,
> +			oneshot_data->invert);

Here when shot is set

echo n > shot

What are the values for blink_delay_on and blink_delay_off. Does user
need to set delay_on and delay_off first? If user doesn't set these then
what values are used?

What about invert? Does user need to do echo 1 > invert and then
activate shot?


Thanks,
-- Shuah
> +
> +	/* content is ignored */
> +	return size;
> +}
> +static ssize_t led_invert_show(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct oneshot_trig_data *oneshot_data = led_cdev->trigger_data;
> +
> +	return sprintf(buf, "%u\n", oneshot_data->invert);
> +}
> +
> +static ssize_t led_invert_store(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t size)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	struct oneshot_trig_data *oneshot_data = led_cdev->trigger_data;
> +	unsigned long state;
> +	int ret;
> +
> +	ret = kstrtoul(buf, 0, &state);
> +	if (ret)
> +		return ret;
> +
> +	oneshot_data->invert = !!state;
> +
> +	return size;
> +}
> +
> +static ssize_t led_delay_on_show(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +
> +	return sprintf(buf, "%lu\n", led_cdev->blink_delay_on);
> +}
> +
> +static ssize_t led_delay_on_store(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t size)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	unsigned long state;
> +	int ret;
> +
> +	ret = kstrtoul(buf, 0, &state);
> +	if (ret)
> +		return ret;
> +
> +	led_cdev->blink_delay_on = state;
> +
> +	return size;
> +}
> +static ssize_t led_delay_off_show(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +
> +	return sprintf(buf, "%lu\n", led_cdev->blink_delay_off);
> +}
> +
> +static ssize_t led_delay_off_store(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t size)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	unsigned long state;
> +	int ret;
> +
> +	ret = kstrtoul(buf, 0, &state);
> +	if (ret)
> +		return ret;
> +
> +	led_cdev->blink_delay_off = state;
> +
> +	return size;
> +}
> +
> +static DEVICE_ATTR(delay_on, 0644, led_delay_on_show, led_delay_on_store);
> +static DEVICE_ATTR(delay_off, 0644, led_delay_off_show, led_delay_off_store);
> +static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);
> +static DEVICE_ATTR(shot, 0200, NULL, led_shot);
> +
> +static void oneshot_trig_activate(struct led_classdev *led_cdev)
> +{
> +	struct oneshot_trig_data *oneshot_data;
> +	int rc;
> +
> +	oneshot_data = kzalloc(sizeof(*oneshot_data), GFP_KERNEL);
> +	if (!oneshot_data)
> +		return;
> +
> +	led_cdev->trigger_data = oneshot_data;
> +
> +	rc = device_create_file(led_cdev->dev, &dev_attr_delay_on);
> +	if (rc)
> +		goto err_out_trig_data;
> +	rc = device_create_file(led_cdev->dev, &dev_attr_delay_off);
> +	if (rc)
> +		goto err_out_delayon;
> +	rc = device_create_file(led_cdev->dev, &dev_attr_invert);
> +	if (rc)
> +		goto err_out_delayoff;
> +	rc = device_create_file(led_cdev->dev, &dev_attr_shot);
> +	if (rc)
> +		goto err_out_invert;
> +
> +	led_cdev->blink_delay_on = DEFAULT_DELAY;
> +	led_cdev->blink_delay_off = DEFAULT_DELAY;
> +
> +	led_cdev->activated = true;
> +
> +	return;
> +
> +err_out_invert:
> +	device_remove_file(led_cdev->dev, &dev_attr_invert);
> +err_out_delayoff:
> +	device_remove_file(led_cdev->dev, &dev_attr_delay_off);
> +err_out_delayon:
> +	device_remove_file(led_cdev->dev, &dev_attr_delay_on);
> +err_out_trig_data:
> +	kfree(led_cdev->trigger_data);
> +}
> +
> +static void oneshot_trig_deactivate(struct led_classdev *led_cdev)
> +{
> +	struct oneshot_trig_data *oneshot_data = led_cdev->trigger_data;
> +
> +	if (led_cdev->activated) {
> +		device_remove_file(led_cdev->dev, &dev_attr_delay_on);
> +		device_remove_file(led_cdev->dev, &dev_attr_delay_off);
> +		device_remove_file(led_cdev->dev, &dev_attr_invert);
> +		device_remove_file(led_cdev->dev, &dev_attr_shot);
> +		kfree(oneshot_data);
> +		led_cdev->activated = false;
> +	}
> +
> +	/* Stop blinking */
> +	led_brightness_set(led_cdev, LED_OFF);
> +}
> +
> +static struct led_trigger oneshot_led_trigger = {
> +	.name     = "oneshot",
> +	.activate = oneshot_trig_activate,
> +	.deactivate = oneshot_trig_deactivate,
> +};
> +
> +static int __init oneshot_trig_init(void)
> +{
> +	return led_trigger_register(&oneshot_led_trigger);
> +}
> +
> +static void __exit oneshot_trig_exit(void)
> +{
> +	led_trigger_unregister(&oneshot_led_trigger);
> +}
> +
> +module_init(oneshot_trig_init);
> +module_exit(oneshot_trig_exit);
> +
> +MODULE_AUTHOR("Fabio Baltieri <fabio.baltieri@gmail.com>");
> +MODULE_DESCRIPTION("One-shot LED trigger");
> +MODULE_LICENSE("GPL");