LED Driver 筆記(翻來的)

想了解 linux kernel 2.6.24.3 中 Driver 的實做，所以先從看起來比較簡單的 LED driver 來開始研究。

S3c2440 LED GPIO:
紅：GPBDAT4
藍：GPBDAT1
綠：GPBDAT10

menuconfig 設定：
Device Drivers --->
[*] LED Support --->
<*> LED Class Support
<*> LED Support for Samsung S3C24XX GPIO LEDs

相關檔案：

• linux/include/linux/leds.h
• linux/include/asm-arm/arch-s3c2410/leds-gpio.h
  
• linux/arch/arm/plat-s3c24xx/common-smdk.c
• linux/driver/leds/leds.h
• linux/driver/leds/led-core.c
• linux/driver/leds/led-class.c
• linux/driver/leds/leds-s3c24xx.c

linux/include/linux/leds.h

/* For the leds-gpio driver */ 
struct gpio_led {
     const char *name;
     char *default_trigger;
     unsigned gpio;
     u8 active_low;
};

struct gpio_led_platform_data {
     int num_leds;
     struct gpio_led *leds;
};

linux/include/asm-arm/arch-s3c2410/leds-gpio.h

struct s3c24xx_led_platdata {
     unsigned int gpio;
     unsigned int flags;

     char *name;
     char *def_trigger;
};

linux/arch/arm/plat-s3c24xx/common-smdk.c
將 led 相關設定內容改成如下：

/* LED devices */
static struct s3c24xx_led_platdata smdk_pdata_led_red = {
.gpio = S3C2410_GPB4,
.flags = S3C24XX_LEDF_TRISTATE,
.name = "led-red",
.def_trigger = "timer",
}

static struct s3c24xx_led_platdata smdk_pdata_led_blue = {
.gpio = S3C2410_GPB1,
.flags = S3C24XX_LEDF_TRISTATE,
.name = "led-blue",
.def_trigger = "nand-disk",
}

static struct s3c24xx_led_platdata smdk_pdata_led_green = {
.gpio = S3C2410_GPB10,
.flags = S3C24XX_LEDF_TRISTATE,
.name = "led-green",
.def_trigger = "led-green",
}

gpio：定義 Led GPIO 接腳
name： device 名字
def_trigger：觸發 led 名稱

static struct platform_device smdk_led_red = {
.name = "s3c24xx_led",
.id = 0,
.dev = {
.platform_data = &smdk_pdata_led_red,
},
}

static struct platform_device smdk_led_blue = {
.name = "s3c24xx_led",
.id = 1,
.dev = {
.platform_data = &smdk_pdata_led_blue,
}
}

static struct platform_device smdk_led_green = {
.name = "s3c24xx_led",
.id = 2,
.dev = {
.platform_data = &smdk_pdata_led_green,
}
}

另外在 smdk_machine_init()
設定初始話 LED 相對應腳位 GPB1 GPB4 GPB10 讓 led 全亮
如下:
s3c2410_gpio_cfgpin(S3C2410_GPB1, S3C2410_GPB1_OUTP);
s3c2410_gpio_cfgpin(S3C2410_GPB4, S3C2410_GPB4_OUTP);
s3c2410_gpio_cfgpin(S3C2410_GPB10,
S3C2410_GPB10_OUTP);

s3c2410_gpio_setpin(S3C2410_GPB1, 1);
s3c2410_gpio_setpin(S3C2410_GPB4, 1);
s3c2410_gpio_setpin(S3C2410_GPB10, 1);

led trigger 在 LED Driver 筆記 - led trigger 會有說明