i.MX Processors中的主题 Re: i.MX6 Device Tree Entry for GPIO based LEDs

i.MX6 Device Tree Entry for GPIO based LEDs

Farrukh — Wed, 27 May 2015 18:07:47 GMT

Greetings All,

I have a custom board based on i.MX6Q and I am running Freescale Linux 3.10.53. I have two user LEDs on GPIO with given configuration. I can start using these LEDs with gpio_led driver by providing following configuration in the machine file (/arch/arm/mach-imx/mach-imx6q.c)

#define GREEN_LED_CLOUD IMX_GPIO_NR(4, 26)

#define GREEN_LED_POWER IMX_GPIO_NR(4, 28)

#define RED_LED_CLOUD IMX_GPIO_NR(4, 27)

#define RED_LED_POWER IMX_GPIO_NR(4, 29)

static const struct gpio_led my_leds[] __initconst = {

{

.name = "led-cloud:green",

.active_low = 1,

.gpio = GREEN_LED_CLOUD,

}, {

.name = "led-cloud:red",

.active_low = 1,

.gpio = RED_LED_CLOUD,

}, {

.name = "led-power:green",

.default_trigger = "heartbeat",

.active_low = 1,

.gpio = GREEN_LED_POWER,

}, {

.name = "led-power:red",

.active_low = 1,

.gpio = RED_LED_POWER,

};

static const struct gpio_led_platform_data my_led_pdata __initconst = {

.num_leds = ARRAY_SIZE(my_leds),

.leds = my_leds,

};

gpio_led_register_device(-1, &my_led_pdata);

But I want to configure these LEDs via Device Tree file. I am not sure exactly how I will add these entries in the Device Tree file. As per my current understanding I have created following node in the Device Tree file.

leds {

compatible = "gpio-leds";

led-green-1 {

label = "Green1";

gpios = <0x15 26 0>; /* 0x15 is defined as GPIO4 */

linux,default-trigger = "heartbeat";

linux,default-state = "on";

};

led-green-2 {

label = "Green2";

gpios = <0x15 28 0>; /* 0x15 is defined as GPIO4 */

linux,default-trigger = "heartbeat";

linux,default-state = "on";

};

led-red-1 {

label = "Red1";

gpios = <0x15 27 0>; /* 0x15 is defined as GPIO4 */

linux,default-trigger = "heartbeat";

linux,default-state = "on";

};

When I start my system, I receive following message for 3 LEDS I have defined in DT file.

leds-gpio leds.26: pins are not configured from the driver

and I can not use LEDs via /sys/class/leds/Green1. If I do echo 1 > /sys/class/leds/Green1/birghtness nothing happens with the LEDs. I suppose I have to define the GPIO muxing somewhere but I can't get where ?

Any help is appreciated.

Regards,

Farrukh Arshad.

Re: i.MX6 Device Tree Entry for GPIO based LEDs

igorpadykov — Thu, 28 May 2015 07:49:48 GMT

Hi Farrukh

could you change to gpios = <&gpio4 26 0>

and check if this will work.

Best regards

igor

Re: i.MX6 Device Tree Entry for GPIO based LEDs

Farrukh — Thu, 28 May 2015 18:33:53 GMT

Hi Igor,

I have tried this but didn't worked. My GPIO node is

gpio4: gpio@020ac000 {

compatible = "fsl,imx6q-gpio", "fsl,imx35-gpio";

reg = <0x20ac000 0x4000>;

interrupts = <0x0 0x4a 0x4 0x0 0x4b 0x4>;

gpio-controller;

#gpio-cells = <0x2>;

interrupt-controller;

#interrupt-cells = <0x2>;

};

But after this change I got following extra messages and I don't see anything in the /sys/class/leds anymore. Earlier gpios = <0x15 26 0> 0x15 was pointing to the wrong GPIO as you have pointed.

leds-gpio leds.27: pins are not configured from the driver

platform leds.27: Driver leds-gpio requests probe deferral

leds-gpio leds.27: pins are not configured from the driver

platform leds.27: Driver leds-gpio requests probe deferral

Thanks

Farrukh

Re: i.MX6 Device Tree Entry for GPIO based LEDs

EricNelson — Thu, 28 May 2015 18:44:05 GMT

Hi Farrukh,

I think you need a pinctrl reference to set up the pads appropriately.

You can find a working example for our Nitrogen6_Lite board here:

linux-imx6/imx6qdl-nit6xlite.dtsi at boundary-imx_3.10.53_1.1.1_ga · boundarydevices/linux-imx6 · GitHub