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

[Bryan Wu]

On Wed, Jun 6, 2012 at 8:51 AM, Shuah Khan <shuahkhan@xxxxxxxxx> wrote:
> 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@xxxxxxxxx>
>> Cc: Shuah Khan <shuahkhan@xxxxxxxxx>
>> Cc: Bryan Wu <bryan.wu@xxxxxxxxxxxxx>
>> ---
>> 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@xxxxxxxxx>
>> + *
>> + * Based on ledtrig-timer.c by Richard Purdie <rpurdie@xxxxxxxxxxxxxx>
>> + *
>> + * 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?
>
>

Exactly, Fabio, what about adding a document for the use case and
sysfs interface?

-Bryan

>> +
>> +     /* 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@xxxxxxxxx>");
>> +MODULE_DESCRIPTION("One-shot LED trigger");
>> +MODULE_LICENSE("GPL");
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