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SubjectRe: LEDs: how to handle gpios that control brightness for all LEDs
* Riku Voipio <riku.voipio@iki.fi> [2008-06-28 20:52]:
> > I have a device that has various gpios that correspond to the colours
> > (blue, red) of various LEDs. They only accept 0/1, not the actual
> > brightness. However, there are two other gpios that can be used to
> > control the brightness (of all LEDs): gpio V_LED 5V is bright, gpio
> > V_LED 3.3V is dimmed and if neither of these two gpios are set, all
> > LEDs stay off.
>
> > Can I simply export these brightness gpios to userland or would it be
> > better to handle the brightness setting in the kernel so that setting
> > e.g. 100 to a LED would automatically set the V_LED 3.3V gpio and 255
> > would set V_LED 5V. If so, how should this be done?
>
> There is a enum led_brightness, which defines LED_HALF and LED_FULL. You
> would need a custom brightness function. Leds-gpio driver would need to
> be extended for it. The main problem with this approach is the
> unexpected effect for enduser, that adjusting brighntess of one led
> affects all of them.

OK, this sounds to me like I should simply export the gpios that
influence the brightness.

> default-on trigger is probably the easiest way.

This works for me, thanks.

New patch below. Any comments Richard?


diff --git a/arch/arm/mach-orion5x/mv2120-setup.c b/arch/arm/mach-orion5x/mv2120-setup.c
index d838bdb..0ac5209 100644
--- a/arch/arm/mach-orion5x/mv2120-setup.c
+++ b/arch/arm/mach-orion5x/mv2120-setup.c
@@ -137,6 +137,50 @@ static struct i2c_board_info __initdata mv2120_i2c_rtc = {
.irq = 0,
};

+static struct gpio_led mv2120_led_pins[] = {
+ {
+ .name = "mv2120:blue:health",
+ .gpio = 0,
+ },
+ {
+ .name = "mv2120:red:health",
+ .gpio = 1,
+ },
+ {
+ .name = "mv2120:led:bright",
+ .gpio = 4,
+ .default_trigger = "default-on",
+ },
+ {
+ .name = "mv2120:led:dimmed",
+ .gpio = 5,
+ },
+ {
+ .name = "mv2120:red:sata0",
+ .gpio = 8,
+ .active_low = 1,
+ },
+ {
+ .name = "mv2120:red:sata1",
+ .gpio = 9,
+ .active_low = 1,
+ },
+
+};
+
+static struct gpio_led_platform_data mv2120_led_data = {
+ .leds = mv2120_led_pins,
+ .num_leds = ARRAY_SIZE(mv2120_led_pins),
+};
+
+static struct platform_device mv2120_leds = {
+ .name = "leds-gpio",
+ .id = -1,
+ .dev = {
+ .platform_data = &mv2120_led_data,
+ }
+};
+
static void mv2120_power_off(void)
{
pr_info("%s: triggering power-off...\n", __func__);
@@ -172,6 +216,7 @@ static void __init mv2120_init(void)
gpio_free(MV2120_GPIO_RTC_IRQ);
}
i2c_register_board_info(0, &mv2120_i2c_rtc, 1);
+ platform_device_register(&mv2120_leds);

/* register mv2120 specific power-off method */
if (gpio_request(MV2120_GPIO_POWER_OFF, "POWEROFF") != 0 ||
--
Martin Michlmayr
http://www.cyrius.com/


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