On Fri, 2008-10-24 at 16:09 -0700, Trent Piepho wrote:
> Let GPIO LEDs get their initial value from whatever the current state of
> the GPIO line is. On some systems the LEDs are put into some state by the
> firmware or hardware before Linux boots, and it is desired to have them
> keep this state which is otherwise unknown to Linux.
>
> This requires that the underlying GPIO driver support reading the value of
> output GPIOs. Some drivers support this and some do not.
>
> The platform data for the platform device binding gets a new field
> 'keep_state' which turns this on. keep_state overrides default_state.
>
> For the OpenFirmware bindings, the "default-state" property gains a new
> allowable setting "keep".
>
> Signed-off-by: Trent Piepho <[EMAIL PROTECTED]>
> diff --git a/drivers/leds/leds-gpio.c b/drivers/leds/leds-gpio.c
> index 0dbad87..bb2a234 100644
> --- a/drivers/leds/leds-gpio.c
> +++ b/drivers/leds/leds-gpio.c
> @@ -92,10 +92,13 @@ static int __devinit create_gpio_led(const struct
> gpio_led *template,
> led_dat->cdev.blink_set = gpio_blink_set;
> }
> led_dat->cdev.brightness_set = gpio_led_set;
> - led_dat->cdev.brightness = template->default_state ? LED_FULL : LED_OFF;
> + if (template->keep_state)
> + state = !!gpio_get_value(led_dat->gpio) ^ led_dat->active_low;
> + else
> + state = template->default_state;
> + led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
>
> - gpio_direction_output(led_dat->gpio,
> - led_dat->active_low ^ template->default_state);
> + gpio_direction_output(led_dat->gpio, led_dat->active_low ^ state);
>
> INIT_WORK(&led_dat->work, gpio_led_work);
>
> @@ -266,6 +269,7 @@ static int __devinit of_gpio_leds_probe(struct of_device
> *ofdev,
> of_get_property(child, "linux,default-trigger", NULL);
> state = of_get_property(child, "default-state", NULL);
> led.default_state = state && !strcmp(state, "on");
> + led.keep_state = state && !strcmp(state, "keep");
>
> ret = create_gpio_led(&led, &pdata->led_data[pdata->num_leds++],
> &ofdev->dev, NULL);
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index caa3987..c51b625 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -138,7 +138,8 @@ struct gpio_led {
> const char *default_trigger;
> unsigned gpio;
> u8 active_low;
> - u8 default_state;
> + u8 default_state; /* 0 = off, 1 = on */
> + u8 keep_state; /* overrides default_state */
> };
How about something simpler here, just make default state have three
different values - "keep", "on" and "off"? I'm not keen on having two
different state variables like this.
Regards,
Richard
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