S3C2440 Linux driver transplantation——LED heartbeat

Development board: TQ2440

Kernel: Linux 2.6.32

PC OS:Ubuntu 11.04

    This article will explain the transplantation of LED drivers. The LED in this article is used to realize heartbeat, that is, after the system is started, the LED will flash at a fixed frequency like a human heart.

Unless the system freezes, the LED will not stop flashing.

1. Configure the kernel, as shown below

2. Modify the code

The TQ2440 development board provides 4 LEDs for user control. This article uses one of the LEDs to implement the heartbeat function.

This LED is connected to GPB5 pin.

Open the file arch/arm/plat-s3c24xx/common-smdk.c

Modify smdk_pdata_led4 to

1. static struct s3c24xx_led_platdata smdk_pdata_led1/*smdk_pdata_led4*/ = {  

2.     .gpio        = S3C2410_GPB(5),//S3C2410_GPF(4),  

3.     .flags        = S3C24XX_LEDF_ACTLOW | S3C24XX_LEDF_TRISTATE,  

4.     .name        = "led1",//"led4",  

5.     .def_trigger    = "heartbeat",//"timer",  

6. };  

Since this is the first LED on the board, change the name to LED1.

Renamed the smdk_led4 structure to smdk_led1.

Modify the smdk_devs array as follows:

1. static struct platform_device __initdata *smdk_devs[] = {  

2.     &s3c_device_nand,  

3.     &smdk_led1,  

4.     //&smdk_led5,  

5.     //&smdk_led6,  

6.     //&smdk_led7,  

7. };  

Finally, modify the smdk_machine_init function as follows:

1. void __init smdk_machine_init(void)  

2. {  

3.     /* Configure the LEDs (even if we have no LED support)*/  

4.   

5.     s3c2410_gpio_cfgpin(S3C2410_GPB(5), S3C2410_GPIO_OUTPUT);  

6.     //s3c2410_gpio_cfgpin(S3C2410_GPF(4), S3C2410_GPIO_OUTPUT);  

7.     //s3c2410_gpio_cfgpin(S3C2410_GPF(5), S3C2410_GPIO_OUTPUT);  

8.     //s3c2410_gpio_cfgpin(S3C2410_GPF(6), S3C2410_GPIO_OUTPUT);  

9.     //s3c2410_gpio_cfgpin(S3C2410_GPF(7), S3C2410_GPIO_OUTPUT);  

10.     s3c2410_gpio_setpin(S3C2410_GPB(5), 1);  

11.     //s3c2410_gpio_setpin(S3C2410_GPF(4), 1);  

12.     //s3c2410_gpio_setpin(S3C2410_GPF(5), 1);  

13.     //s3c2410_gpio_setpin(S3C2410_GPF(6), 1);  

14.     //s3c2410_gpio_setpin(S3C2410_GPF(7), 1);  

15.   

16.     if (machine_is_smdk2443())  

17.         smdk_nand_info.twrph0 = 50;  

18.   

19.     s3c_device_nand.dev.platform_data = &smdk_nand_info;  

20.   

21.     platform_add_devices(smdk_devs, ARRAY_SIZE(smdk_devs));  

22.   

23.     s3c_pm_init();  

24. }  

3. Verification

Compile the kernel, burn it, and run it.

After the system starts, the LED starts flashing and can be seen in the sys file system as follows:

[root@yj423 leds]#pwd
/sys/class/leds
[root@yj423 leds]#ls
led1