Re: [PATCH] leds: trigger/tty: Add knob to blink only for tx or only for rx

[Alexander Dahl <ada@thorsis.com>]

Hello Uwe,

Am Thu, Feb 24, 2022 at 04:56:55PM +0100 schrieb Uwe Kleine-König:
> The newly introduced "triggerevent" attribute allows to restrict
> blinking to TX or RX only.

Sounds like you could hook up the trigger for the same UART to one LED
with RX only and to another LED with TX only.  Right?

This could be very useful for me in the future, I just don't have the
ressources to test this soon. :-/

Greets
Alex

> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>  .../ABI/testing/sysfs-class-led-trigger-tty   |  9 +++
>  drivers/leds/trigger/ledtrig-tty.c            | 60 ++++++++++++++++++-
>  2 files changed, 67 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-led-trigger-tty b/Documentation/ABI/testing/sysfs-class-led-trigger-tty
> index 2bf6b24e781b..27532f685b0d 100644
> --- a/Documentation/ABI/testing/sysfs-class-led-trigger-tty
> +++ b/Documentation/ABI/testing/sysfs-class-led-trigger-tty
> @@ -4,3 +4,12 @@ KernelVersion:	5.10
>  Contact:	linux-leds@vger.kernel.org
>  Description:
>  		Specifies the tty device name of the triggering tty
> +
> +What:		/sys/class/leds/<led>/triggerevent
> +Date:		Feb 2022
> +KernelVersion:	5.18
> +Contact:	linux-leds@vger.kernel.org
> +Description:
> +		Can contain "tx', "rx" (to only blink on transfers
> +		in the specified direction) or "both" (to blink for
> +		both directions.)
> diff --git a/drivers/leds/trigger/ledtrig-tty.c b/drivers/leds/trigger/ledtrig-tty.c
> index f62db7e520b5..f87877ca48d4 100644
> --- a/drivers/leds/trigger/ledtrig-tty.c
> +++ b/drivers/leds/trigger/ledtrig-tty.c
> @@ -14,6 +14,7 @@ struct ledtrig_tty_data {
>  	const char *ttyname;
>  	struct tty_struct *tty;
>  	int rx, tx;
> +	bool handle_rx, handle_tx;
>  };
>  
>  static void ledtrig_tty_restart(struct ledtrig_tty_data *trigger_data)
> @@ -76,6 +77,57 @@ static ssize_t ttyname_store(struct device *dev,
>  }
>  static DEVICE_ATTR_RW(ttyname);
>  
> +static ssize_t triggerevent_show(struct device *dev,
> +				 struct device_attribute *attr, char *buf)
> +{
> +	struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);
> +	ssize_t len = 0;
> +
> +	mutex_lock(&trigger_data->mutex);
> +
> +	if (trigger_data->handle_tx && trigger_data->handle_rx)
> +		len = sprintf(buf, "both\n");
> +	else if (trigger_data->handle_tx)
> +		len = sprintf(buf, "tx\n");
> +	else
> +		len = sprintf(buf, "rx\n");
> +
> +	mutex_unlock(&trigger_data->mutex);
> +
> +	return len;
> +}
> +
> +static ssize_t triggerevent_store(struct device *dev,
> +				  struct device_attribute *attr,
> +				  const char *buf, size_t size)
> +{
> +	struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);
> +	ssize_t ret = size;
> +
> +	if (size > 0 && buf[size - 1] == '\n')
> +		size -= 1;
> +
> +	mutex_lock(&trigger_data->mutex);
> +
> +	if (!strncmp(buf, "both", size)) {
> +		trigger_data->handle_tx = true;
> +		trigger_data->handle_rx = true;
> +	} else if (!strncmp(buf, "tx", size)) {
> +		trigger_data->handle_tx = true;
> +		trigger_data->handle_rx = false;
> +	} else if (!strncmp(buf, "rx", size)) {
> +		trigger_data->handle_tx = false;
> +		trigger_data->handle_rx = true;
> +	} else {
> +		ret = -EINVAL;
> +	}
> +
> +	mutex_unlock(&trigger_data->mutex);
> +
> +	return ret;
> +}
> +static DEVICE_ATTR_RW(triggerevent);
> +
>  static void ledtrig_tty_work(struct work_struct *work)
>  {
>  	struct ledtrig_tty_data *trigger_data =
> @@ -120,8 +172,8 @@ static void ledtrig_tty_work(struct work_struct *work)
>  		return;
>  	}
>  
> -	if (icount.rx != trigger_data->rx ||
> -	    icount.tx != trigger_data->tx) {
> +	if ((icount.rx != trigger_data->rx && trigger_data->handle_rx) ||
> +	    (icount.tx != trigger_data->tx && trigger_data->handle_tx)) {
>  		led_set_brightness_sync(trigger_data->led_cdev, LED_ON);
>  
>  		trigger_data->rx = icount.rx;
> @@ -137,6 +189,7 @@ static void ledtrig_tty_work(struct work_struct *work)
>  
>  static struct attribute *ledtrig_tty_attrs[] = {
>  	&dev_attr_ttyname.attr,
> +	&dev_attr_triggerevent.attr,
>  	NULL
>  };
>  ATTRIBUTE_GROUPS(ledtrig_tty);
> @@ -155,6 +208,9 @@ static int ledtrig_tty_activate(struct led_classdev *led_cdev)
>  	trigger_data->led_cdev = led_cdev;
>  	mutex_init(&trigger_data->mutex);
>  
> +	trigger_data->handle_tx = true;
> +	trigger_data->handle_rx = true;
> +
>  	return 0;
>  }
>  
> -- 
> 2.34.1
> 

-- 
Alexander Dahl           Thorsis Technologies GmbH   T +49 391 544 563 1000
Industrieautomation      Oststr. 18                  F +49 391 544 563 9099
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