Android system （ Led class 节点添加）

亦余心之所善兮，虽九死其犹未悔。这篇文章主要讲述Android system ： Led class 节点添加相关的知识，希望能为你提供帮助。
一、代码：
leds_4412.c

#include < linux/kernel.h> #include < linux/module.h> #include < linux/miscdevice.h> #include < linux/device.h> #include < linux/fs.h> #include < linux/types.h> #include < linux/moduleparam.h> #include < linux/slab.h> #include < linux/ioctl.h> #include < linux/cdev.h> #include < linux/delay.h> #include < linux/gpio.h> #include < mach/gpio.h> #include < plat/gpio-cfg.h> #include < linux/leds.h> struct led_desc { int gpio; char *name; }; static struct led_desc led_gpios[] = { {EXYNOS4212_GPM4(0), "led1"}, {EXYNOS4212_GPM4(1), "led2"}, {EXYNOS4212_GPM4(2), "led3"}, {EXYNOS4212_GPM4(3), "led4"}, }; struct led_classdev_4412 { struct led_classdev cdev; int gpio; }; static struct led_classdev_4412 *led_devs; static voidbrightness_set_4412(struct led_classdev *led_cdev, enum led_brightness brightness) { struct led_classdev_4412 *dev = (struct led_classdev_4412 *)led_cdev; led_cdev-> brightness = brightness; if (brightness != LED_OFF) gpio_set_value(dev-> gpio, 0); else gpio_set_value(dev-> gpio, 1); }static int leds_init(void) { int i; int ret; /* 1. alloc led_classdev */ led_devs = kzalloc(sizeof(struct led_classdev_4412) * sizeof(led_gpios)/sizeof(led_gpios[0]), GFP_KERNEL); if (led_devs == NULL) { printk("No memory for device\n"); return -ENOMEM; }for (i = 0; i < sizeof(led_gpios)/sizeof(led_gpios[0]); i++) {s3c_gpio_cfgpin(led_gpios[i].gpio, S3C_GPIO_OUTPUT); gpio_set_value(led_gpios[i].gpio, 1); /* 2. set */ led_devs[i].cdev.max_brightness = LED_FULL; led_devs[i].cdev.brightness_set = brightness_set_4412; led_devs[i].cdev.flags = LED_CORE_SUSPENDRESUME; led_devs[i].cdev.brightness = LED_OFF; led_devs[i].cdev.name = led_gpios[i].name; //led_devs[i].cdev.default_trigger = "timer"; led_devs[i].gpio = led_gpios[i].gpio; /* 3. led_classdev_register */ ret = led_classdev_register(NULL, & led_devs[i].cdev); if (ret) { i--; while (i > = 0) { led_classdev_unregister(& led_devs[i].cdev); i--; } kfree(led_devs); return -EIO; } }return 0; }static void leds_exit(void) { int i; for (i = 0; i < sizeof(led_gpios)/sizeof(led_gpios[0]); i++) { led_classdev_unregister(& led_devs[i].cdev); } kfree(led_devs); }module_init(leds_init); module_exit(leds_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("sheldon");

二、编译测试：
把 leds_4412.c 放到drivers/leds
修改 drivers/leds/Makefile:
obj-y += leds_4412.o
重新配置内核
make menuconfig
CONFIG_LEDS_CLASS
CONFIG_LEDS_TRIGGERS
CONFIG_LEDS_TRIGGER_TIMER
【Android system （ Led class 节点添加）】-> Device Drivers
-> LED Support
[*]LED Class Support
[*]LED Trigger support
< *> LED Timer Trigger

重新编译内核： make zImage