原理图：
驱动程序代码：
myleds.c #include <linux/module.h> #include <linux/kernel.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/delay.h> #include <asm/uaccess.h> #include <asm/irq.h> #include <asm/io.h> #include <asm/arch/regs-gpio.h> #include <asm/hardware.h>#define DEVICE_NAME "leds" /* 加载模式后，执行”cat /proc/devices”命令看到的设备名称 */ #define LED_MAJOR 231 /* 主设备号 */static struct class *leds_class; static struct class_device *leds_class_devs[4];/* bit0<=>D10, 0:亮, 1:灭 * bit1<=>D11, 0:亮, 1:灭 * bit2<=>D12, 0:亮, 1:灭 */ static char leds_status = 0x0; static DECLARE_MUTEX(leds_lock); // 定义赋值//static int minor; static unsigned long gpio_va;#define GPIO_OFT(x) ((x) - 0x56000000) #define GPFCON (*(volatile unsigned long *)(gpio_va + GPIO_OFT(0x56000050))) #define GPFDAT (*(volatile unsigned long *)(gpio_va + GPIO_OFT(0x56000054)))/* 应用程序对设备文件/dev/leds执行open(...)时，* 就会调用s3c24xx_leds_open函数*/ static int s3c24xx_leds_open(struct inode *inode, struct file *file) {int minor = MINOR(inode->i_rdev); //MINOR(inode->i_cdev);switch(minor){case 0: /* /dev/leds */{// 配置3引脚为输出//s3c2410_gpio_cfgpin(S3C2410_GPF4, S3C2410_GPF4_OUTP);GPFCON &= ~(0x3<<(4*2));GPFCON |= (1<<(4*2));//s3c2410_gpio_cfgpin(S3C2410_GPF5, S3C2410_GPF5_OUTP);GPFCON &= ~(0x3<<(5*2));GPFCON |= (1<<(5*2));//s3c2410_gpio_cfgpin(S3C2410_GPF6, S3C2410_GPF6_OUTP);GPFCON &= ~(0x3<<(6*2));GPFCON |= (1<<(6*2));// 都输出0//s3c2410_gpio_setpin(S3C2410_GPF4, 0);GPFDAT &= ~(1<<4);//s3c2410_gpio_setpin(S3C2410_GPF5, 0);GPFDAT &= ~(1<<5);//s3c2410_gpio_setpin(S3C2410_GPF6, 0);GPFDAT &= ~(1<<6);down(&leds_lock);leds_status = 0x0;up(&leds_lock);break;}case 1: /* /dev/led1 */{s3c2410_gpio_cfgpin(S3C2410_GPF4, S3C2410_GPF4_OUTP);s3c2410_gpio_setpin(S3C2410_GPF4, 0);down(&leds_lock);leds_status &= ~(1<<0);up(&leds_lock);break;}case 2: /* /dev/led2 */{s3c2410_gpio_cfgpin(S3C2410_GPF5, S3C2410_GPF5_OUTP);s3c2410_gpio_setpin(S3C2410_GPF5, 0);leds_status &= ~(1<<1);break;}case 3: /* /dev/led3 */{s3c2410_gpio_cfgpin(S3C2410_GPF6, S3C2410_GPF6_OUTP);s3c2410_gpio_setpin(S3C2410_GPF6, 0);down(&leds_lock);leds_status &= ~(1<<2);up(&leds_lock);break;}}return 0; }static int s3c24xx_leds_read(struct *filp, char __user *buff, size_t count, loff_t *offp) {int minor = MINOR(filp->f_dentry->d_inode->i_rdev);char val;switch (minor){case 0: /* /dev/leds */{copy_to_user(buff, (const void *)&leds_status, 1); break;}case 1: /* /dev/led1 */{down(&leds_lock);val = leds_status & 0x1;up(&leds_lock);copy_to_user(buff, (const void *)&val, 1);break;}case 2: /* /dev/led2 */{down(&leds_lock);val = (leds_status>>1) & 0x1;up(&leds_lock);copy_to_user(buff, (const void *)&val, 1);break;}case 3: /* /dev/led3 */{down(&leds_lock);val = (leds_status>>2) & 0x1;up(&leds_lock);copy_to_user(buff, (const void *)&val, 1);break;}}return 1; }static ssize_t s3c24xx_leds_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos) {//int minor = MINOR(inode->i_rdev); //MINOR(inode->i_cdev);int minor = MINOR(file->f_dentry->d_inode->i_rdev);char val;copy_from_user(&val, buf, 1);switch (minor){case 0: /* /dev/leds */{ s3c2410_gpio_setpin(S3C2410_GPF4, (val & 0x1));s3c2410_gpio_setpin(S3C2410_GPF5, (val & 0x1));s3c2410_gpio_setpin(S3C2410_GPF6, (val & 0x1));down(&leds_lock);leds_status = val;up(&leds_lock);break;}case 1: /* /dev/led1 */{s3c2410_gpio_setpin(S3C2410_GPF4, val);if (val == 0){down(&leds_lock);leds_status &= ~(1<<0);up(&leds_lock);}else{down(&leds_lock);leds_status |= (1<<0); up(&leds_lock);}break;}case 2: /* /dev/led2 */{s3c2410_gpio_setpin(S3C2410_GPF5, val);if (val == 0){down(&leds_lock);leds_status &= ~(1<<1);up(&leds_lock);}else{down(&leds_lock);leds_status |= (1<<1); up(&leds_lock);}break;}case 3: /* /dev/led3 */{s3c2410_gpio_setpin(S3C2410_GPF6, val);if (val == 0){down(&leds_lock);leds_status &= ~(1<<2);up(&leds_lock);}else{down(&leds_lock);leds_status |= (1<<2); up(&leds_lock);}break;}}return 1; }/* 这个结构是字符设备驱动程序的核心* 当应用程序操作设备文件时所调用的open、read、write等函数，* 最终会调用这个结构中指定的对应函数*/ static struct file_operations s3c24xx_leds_fops = {.owner = THIS_MODULE, /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */.open = s3c24xx_leds_open, .read = s3c24xx_leds_read, .write = s3c24xx_leds_write, };/** 执行insmod命令时就会调用这个函数 */ static int __init s3c24xx_leds_init(void) //static int __init init_module(void) {int ret;int minor = 0;gpio_va = ioremap(0x56000000, 0x100000);if (!gpio_va) {return -EIO;}/* 注册字符设备* 参数为主设备号、设备名字、file_operations结构；* 这样，主设备号就和具体的file_operations结构联系起来了，* 操作主设备为LED_MAJOR的设备文件时，就会调用s3c24xx_leds_fops中的相关成员函数* LED_MAJOR可以设为0，表示由内核自动分配主设备号*/ret = register_chrdev(LED_MAJOR, DEVICE_NAME, &s3c24xx_leds_fops);if (ret < 0) {printk(DEVICE_NAME " can't register major number\n");return ret;}leds_class = class_create(THIS_MODULE, "leds");if (IS_ERR(leds_class))return PTR_ERR(leds_class);leds_class_devs[0] = class_device_create(leds_class, NULL, MKDEV(LED_MAJOR, 0), NULL, "leds");for (minor = 1; minor < 4; minor++){leds_class_devs[minor] = class_device_create(leds_class, NULL, MKDEV(LED_MAJOR, minor), NULL, "led%d", minor);if (unlikely(IS_ERR(leds_class_devs[minor])))return PTR_ERR(leds_class_devs[minor]);}printk(DEVICE_NAME " initialized\n");return 0; }/** 执行rmmod命令时就会调用这个函数 */ static void __exit s3c24xx_leds_exit(void) {int minor;/* 卸载驱动程序 */unregister_chrdev(LED_MAJOR, DEVICE_NAME);for (minor = 0; minor < 4; minor++){class_device_unregister(leds_class_devs[minor]);}class_destroy(leds_class);iounmap(gpio_va); }/* 这两行指定驱动程序的初始化函数和卸载函数 */ module_init(s3c24xx_leds_init); module_exit(s3c24xx_leds_exit);/* 描述驱动程序的一些信息，不是必须的 */ MODULE_AUTHOR("http://www.100ask.net"); MODULE_VERSION("0.1.0"); MODULE_DESCRIPTION("S3C2410/S3C2440 LED Driver"); MODULE_LICENSE("GPL");
应用程序代码：
ledtest.c #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h>/** ledtest <dev> <on|off>*/void print_usage(char *file) {printf("Usage:\n");printf("%s <dev> <on|off>\n",file);printf("eg. \n");printf("%s /dev/leds on\n", file);printf("%s /dev/leds off\n", file);printf("%s /dev/led1 on\n", file);printf("%s /dev/led1 off\n", file); }int main(int argc, char **argv) {int fd;char* filename;char val;if (argc != 3){print_usage(argv[0]);return 0;}filename = argv[1];fd = open(filename, O_RDWR);if (fd < 0){printf("error, can't open %s\n", filename);return 0;}if (!strcmp("on", argv[2])){// 亮灯val = 0;write(fd, &val, 1);}else if (!strcmp("off", argv[2])){// 灭灯val = 1;write(fd, &val, 1);}else{print_usage(argv[0]);return 0;}return 0; }
