Re: [PATCH 2/2] leds: trigger: ledtrig-tty: add additional modes

Jiri Slaby
2023-02-14T07:54:39Z

On 13. 02. 23, 15:06, Florian Eckert wrote:
> Add additional modes to trigger the selected LED.
> The following modes are supported:
>
> TD/RD: Flash LED on data transmission (default)
> CTS: DCE Ready to accept data from the DTE.
> DSR: DCE is ready to receive and send data.
> CAR: DCE is receiving a carrier from a remote DTE.
> RNG: DCE has detected an incoming ring signal.
>
> The mode can be changed for example with the following command:
> echo "CTS" /sys/class/leds/<led>/mode

This will emit only:
CTS /sys/class/leds/<led>/mode

> This would turn on the LED, when the DTE(modem) signals the DCE that it
> is ready to accept data.
>
> Signed-off-by: Florian Eckert <fe@dev.tdt.de>
...
> --- a/drivers/leds/trigger/ledtrig-tty.c
> +++ b/drivers/leds/trigger/ledtrig-tty.c
> @@ -7,6 +7,14 @@
> #include <linux/tty.h>
> #include <uapi/linux/serial.h>
>
> +enum tty_led_mode {
> + TTY_LED_CNT,
> + TTY_LED_CTS,
> + TTY_LED_DSR,
> + TTY_LED_CAR,
> + TTY_LED_RNG,
> +};
> +
> struct ledtrig_tty_data {
> struct led_classdev *led_cdev;
> struct delayed_work dwork;
> @@ -14,6 +22,15 @@ struct ledtrig_tty_data {
> const char *ttyname;
> struct tty_struct *tty;
> int rx, tx;
> + unsigned int mode;

Why not the enum then?

> +};
> +
> +static const char * const mode[] = {

This is not a wise name.

> + [TTY_LED_CNT] = "TD/RD", // Trasmit Data / Receive Data
> + [TTY_LED_CTS] = "CTS", // CTS Clear To Send
> + [TTY_LED_DSR] = "DSR", // DSR Data Set Ready
> + [TTY_LED_CAR] = "CAR", // CAR Data Carrier Detect (DCD)
> + [TTY_LED_RNG] = "RNG", // RNG Ring Indicator (RI)
> };
>
> static void ledtrig_tty_restart(struct ledtrig_tty_data *trigger_data)
> @@ -21,6 +38,74 @@ static void ledtrig_tty_restart(struct ledtrig_tty_data *trigger_data)
> schedule_delayed_work(&trigger_data->dwork, 0);
> }
>
> +static ssize_t mode_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);
> + enum tty_led_mode tty_mode;
> +
> + mutex_lock(&trigger_data->mutex);
> + tty_mode = trigger_data->mode;
> + mutex_unlock(&trigger_data->mutex);
> +
> + switch (tty_mode) {
> + case TTY_LED_CTS:
> + return sprintf(buf, "%s [%s] %s %s %s\n", mode[TTY_LED_CNT],
> + mode[TTY_LED_CTS], mode[TTY_LED_DSR],
> + mode[TTY_LED_CAR], mode[TTY_LED_RNG]);
> + case TTY_LED_DSR:
> + return sprintf(buf, "%s %s [%s] %s %s\n", mode[TTY_LED_CNT],
> + mode[TTY_LED_CTS], mode[TTY_LED_DSR],
> + mode[TTY_LED_CAR], mode[TTY_LED_RNG]);
> + case TTY_LED_CAR:
> + return sprintf(buf, "%s %s %s [%s] %s\n", mode[TTY_LED_CNT],
> + mode[TTY_LED_CTS], mode[TTY_LED_DSR],
> + mode[TTY_LED_CAR], mode[TTY_LED_RNG]);
> + case TTY_LED_RNG:
> + return sprintf(buf, "%s %s %s %s [%s]\n", mode[TTY_LED_CNT],
> + mode[TTY_LED_CTS], mode[TTY_LED_DSR],
> + mode[TTY_LED_CAR], mode[TTY_LED_RNG]);
> + case TTY_LED_CNT:
> + default:
> + return sprintf(buf, "[%s] %s %s %s %s\n", mode[TTY_LED_CNT],
> + mode[TTY_LED_CTS], mode[TTY_LED_DSR],
> + mode[TTY_LED_CAR], mode[TTY_LED_RNG]);

Can't we do the above in a loop easier?

> +static ssize_t mode_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;
> + enum tty_led_mode tty_mode;
> +
> + /* Check for new line in string*/
> + if (size > 0 && buf[size - 1] == '\n')
> + size -= 1;
> +
> + if (strncmp(buf, mode[TTY_LED_CTS], size) == 0)
> + tty_mode = TTY_LED_CTS;
> + else if (strncmp(buf, mode[TTY_LED_DSR], size) == 0)
> + tty_mode = TTY_LED_DSR;
> + else if (strncmp(buf, mode[TTY_LED_CAR], size) == 0)
> + tty_mode = TTY_LED_CAR;
> + else if (strncmp(buf, mode[TTY_LED_RNG], size) == 0)
> + tty_mode = TTY_LED_RNG;
> + else if (strncmp(buf, mode[TTY_LED_CNT], size) == 0)
> + tty_mode = TTY_LED_CNT;
> + else
> + return -EINVAL;

Again, a loop?

> +
> + mutex_lock(&trigger_data->mutex);
> + trigger_data->mode = tty_mode;
> + mutex_unlock(&trigger_data->mutex);
> +
> + return ret;
> +}
> +static DEVICE_ATTR_RW(mode);
> +
> static ssize_t ttyname_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> @@ -76,6 +161,18 @@ static ssize_t ttyname_store(struct device *dev,
> }
> static DEVICE_ATTR_RW(ttyname);
>
> +static void ledtrig_tty_flags(struct ledtrig_tty_data *trigger_data,
> + unsigned int flag)
> +{
> + unsigned int status;
> +
> + status = tty_get_mget(trigger_data->tty);

So what about negative values = errors?

> + if (status & flag)

They really might hit here.

> + led_set_brightness_sync(trigger_data->led_cdev, LED_ON);
> + else
> + led_set_brightness_sync(trigger_data->led_cdev, LED_OFF);
> +}
> +

thanks,
--
js
suse labs