setting leds in linux kernel

Hi Trichet,

Have you tried to control the GPIO through commands "SYSFS"  instead of trying through "C" app ?

http://processors.wiki.ti.com/index.php/Linux_PSP_GPIO_Driver_Guide#User_Space_-_Sysfs_control

Try the below commands and update me the results.

Note:

Mention your appropriate GPIO no instead 45.

echo 45 > /sys/class/gpio/export

echo "out" > /sys/class/gpio/gpio45/direction

echo 0 > /sys/class/gpio/gpio45/value

echo 1 > /sys/class/gpio/gpio45/value

Hello

thanks for your reply

1) I added  at the end of am335x_evm_setup the following code

    int status = gpio_request(GPIO_TO_PIN(2, 12),"DEF");
    if (status < 0)
        pr_err("Failed to request GPIO DEF");
    else
    {
        gpio_direction_output(GPIO_TO_PIN(2, 12), 0);
        gpio_free(GPIO_TO_PIN(2, 12));
    }

with the free function i get no error using sysfs command (echo 45 > /sys/class/gpio/export)

But with this function the gpio doesn't stay to 0. How can i impose a value on an IO, and then use it with sysfs command in an application ?

Thanks

Hi Trichet,

What is the output of "GPIO_TO_PIN(2, 12)" ie GPIO pin no ?

Please make sure that you are not used the GPIO for any other peripheral.

Like LCD , GPMC etc.,

Have you configured the "LCD_DATA6" pin as MODE7 in linux source.

Hello

thanks for the reply

In U-boot/MLO the GPIO is cleared using : gpio_direction_output( 76, 0); it's OK

But when linux is launched this IO returns to 1

This IO is number 76, it is not re-configured in the following file (the code used is under #ifdef UCR_BOARD) :

8461.board-am335xevm.c

Has the pinumx is not re-defined in this file i shouldn't have problem ?

Thanks

Hi Trichet,

Try the below code in your board file and update the results with logs and confirm the LED status too ie whether the LEDs are blinking or not.

Include "#include <linux/delay.h>" in board file.

static void gpio_led_init(int evm_id, int profile)
{
	int status;
#if 0
	int err;

	setup_pin_mux(gpio_led_mux);
	err = platform_device_register(&leds_gpio);
	if (err)
		pr_err("failed to register gpio led device\n");
#endif

#ifdef UCR_BOARD
//V1.2
	pr_info("Configure led INIT and DEF!!!!!!!!!!!!!!!!!!!!!!!!!!!...\n");
		status = gpio_request(GPIO_TO_PIN(2, 12),NULL);
		printk("GPIO76 REQUEST STATUS is %p\n",status);
		gpio_direction_output(GPIO_TO_PIN(2, 12), 0);
		mdelay(2000)	//2 sec delay so that we can see that LED blinking
		gpio_set_value(GPIO_TO_PIN(2, 12),1);	//OFF
		mdelay(2000)	//2 sec delay so that we can see that LED blinking
		gpio_set_value(GPIO_TO_PIN(2, 12),0);	//ON

		gpio_free(GPIO_TO_PIN(2, 13));
	pr_info("DONE !!!\n");
#endif

}

Hello

thanks for the reply, that OK i can see the blinking done by gpio_led_init() function.

By under linux prompt i don't have access to that IO :

root@am335x-evm:~# echo 76 > /sys/class/gpio/export                             
-sh: echo: write error: Device or resource busy                                 
s/class/gpio/gpio76/value                                                       
root@am335x-evm:~# echo "out" > /sys/class/gpio/gpio76/direction                
-sh: /sys/class/gpio/gpio76/direction: No such file or directory                
root@am335x-evm:~# echo 0 > /sys/class/gpio/gpio76/value                        
-sh: /sys/class/gpio/gpio76/value: No such file or directory  

Is there a way to unexport in IO ?

The test was done using the code :

static struct pinmux_config gpio_led_mux[] = {
//V1.2
#ifdef UCR_BOARD
    {"lcd_data6.gpio2_12", OMAP_MUX_MODE7 | AM33XX_PIN_OUTPUT},
    {"lcd_data7.gpio2_13", OMAP_MUX_MODE7 | AM33XX_PIN_OUTPUT},
    {NULL, 0},
#else
    {"gpmc_ad4.gpio1_4", OMAP_MUX_MODE7 | AM33XX_PIN_INPUT},
    {"gpmc_ad5.gpio1_5", OMAP_MUX_MODE7 | AM33XX_PIN_INPUT},
    {"gpmc_ad6.gpio1_6", OMAP_MUX_MODE7 | AM33XX_PIN_INPUT},
    {"gpmc_ad7.gpio1_7", OMAP_MUX_MODE7 | AM33XX_PIN_INPUT},
    {NULL, 0},
#endif
};

static struct gpio_led gpio_leds[] = {
//V1.2
#ifdef UCR_BOARD
    {
        .name            = "INIT",
        .gpio            = GPIO_TO_PIN(2, 12),    
    },
    {
        .name            = "DEF",
        .gpio            = GPIO_TO_PIN(2, 13),    
    },
#else
    {
        .name            = "am335x:EVM_SK:usr0",
        .gpio            = GPIO_TO_PIN(1, 4),    /* D1 */
    },
    {
        .name            = "am335x:EVM_SK:usr1",
        .gpio            = GPIO_TO_PIN(1, 5),    /* D2 */
    },
    {
        .name            = "am335x:EVM_SK:mmc0",
        .gpio            = GPIO_TO_PIN(1, 7),    /* D3 */
        .default_trigger    = "mmc0",
    },
    {
        .name            = "am335x:EVM_SK:heartbeat",
        .gpio            = GPIO_TO_PIN(1, 6),    /* D4 */
        .default_trigger    = "heartbeat",
    },
#endif
};

static void gpio_led_init(int evm_id, int profile)
{
    int err;

    setup_pin_mux(gpio_led_mux);
    err = platform_device_register(&leds_gpio);
    if (err)
        pr_err("failed to register gpio led device\n");


    pr_info("Configure led INIT and DEF!!!!!!!!!!!!!!!!!!!!!!!!!!!...\n");
        int status = gpio_request(GPIO_TO_PIN(2, 12),NULL);
        printk("GPIO76 REQUEST STATUS is %p\n",status);
        gpio_direction_output(GPIO_TO_PIN(2, 12), 0);
        mdelay(2000);    //2 sec delay so that we can see that LED blinking
        gpio_set_value(GPIO_TO_PIN(2, 12),1);    //OFF
        mdelay(2000);    //2 sec delay so that we can see that LED blinking
        gpio_set_value(GPIO_TO_PIN(2, 12),0);    //ON

        gpio_free(GPIO_TO_PIN(2, 13));
    pr_info("DONE !!!\n");




}

Hi Trichet,

Hello

thanks for the reply, that OK i can see the blinking done by gpio_led_init() function.

By under linux prompt i don't have access to that IO :

root@am335x-evm:~# echo 76 > /sys/class/gpio/export                             
-sh: echo: write error: Device or resource busy                                 
s/class/gpio/gpio76/value                                              

I've done a mistake and sorry for that.

Just I've used your code and modified slightly.

I freed the GPIO2_13 but not GPIO2_12 right ?

Now I've freed the GPIO2_12 and have a try.

static void gpio_led_init(int evm_id, int profile)
{
    int status;
#if 0
    int err;
    setup_pin_mux(gpio_led_mux);
    err = platform_device_register(&leds_gpio);
    if (err)
        pr_err("failed to register gpio led device\n");
#endif
#ifdef UCR_BOARD
//V1.2
    pr_info("Configure led INIT and DEF!!!!!!!!!!!!!!!!!!!!!!!!!!!...\n");
        status = gpio_request(GPIO_TO_PIN(2, 12),NULL);
        printk("GPIO76 REQUEST STATUS is %p\n",status);
        gpio_direction_output(GPIO_TO_PIN(2, 12), 0);
        mdelay(2000)    //2 sec delay so that we can see the LED blinking
        gpio_set_value(GPIO_TO_PIN(2, 12),1);   //OFF
        mdelay(2000)    //2 sec delay so that we can see the LED blinking
        gpio_set_value(GPIO_TO_PIN(2, 12),0);   //ON
        gpio_free(GPIO_TO_PIN(2, 12));
    pr_info("DONE !!!\n");
#endif
}

Hello

thanks for the reply

i have tried the free(76), with no more success :

           
[    0.965393] Configure led INIT and DEF!!!!!!!!!!!!!!!!!!!!!!!!!!!...         
[    0.972045] GPIO76 REQUEST STATUS is   (null)                                
[    4.974182] DONE !!!                                                         
[

root@am335x-evm:~# echo 76 > /sys/class/gpio/export                             
-sh: echo: write error: Device or resource busy                                 
lass/gpio/gpio76/value                                                          
root@am335x-evm:~# echo "out" > /sys/class/gpio/gpio76/direction                
-sh: /sys/class/gpio/gpio76/direction: No such file or directory                
root@am335x-evm:~# echo 0 > /sys/class/gpio/gpio76/value                        
-sh: /sys/class/gpio/gpio76/value: No such file or directory

Shouldn't we use the function

     int gpiod_export(struct gpio_desc *desc, bool direction_may_change);

 /* export the GPIO to userspace */

Have you any idea ?

best regards

Thank for the reply

now that is OK

The only problem is a de-programmation of about 1s when linux boots. I put my code

        int status = gpio_request(GPIO_TO_PIN(2, 12),NULL);
        //printk("GPIO76 REQUEST STATUS is %p\n",status);
        gpio_direction_output(GPIO_TO_PIN(2, 12), 0);
        gpio_set_value(GPIO_TO_PIN(2, 12),0);    //ON
        gpio_export(GPIO_TO_PIN(2, 12),true);

in am335x_evm_init , am335x_evm_setup, gpio_led_init functions to force to 0 the GPIO

I don't undertsand why this IO is momentanuously de-programmed

Any idea

Regards

Hi Trichet,

Currently what problem are you facing ?

Not able to control the GPIO from user space using "echo 0 > /sys/class/gpio/gpio76/value" ?

Hello

thanks for the reply.

No the problem is that i set gpio76 to 0 in u-boot, but it returns to 1 when linux is lauched, for 60ms, before i put it again to 0 in gpio_led_init().

I' m wondering where in linux the GPIO maybe modified

Regards

Hi Trichet,

Remove this "lcdc_pin_mux" declaration in your board file and try.

Please ensure that you have not used "LCD_D6" data line which is pinmuxed with 'GPIO2_12' in board file or dts file.

Hello

thanks for the reply. I have patched the lcdc_pin_mux with no success (lcdc_init() function was not called anyway)

7585.board-am335xevm.c

What do you mean by dts file ?

Thanks

Hi Trichet,

'dts' means "device tree source"

Nowadays we are using "dts" support in linux for configuring what board file does.

arch/arm/boot/dts/

Hello

Thanks for the reply

i have no device tree for that linux distribution.

The GPIO 76 is set to 1 when linux starts; it is done before we enter the  __init am335x_evm_init() function.

What function may change u-boot IO configuration ?

Thanks