驱动代码：
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/init.h>
#include <linux/serio.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/miscdevice.h>
#include <linux/gpio.h> #include <asm/io.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include <mach/regs-clock.h>
#include <plat/regs-timer.h> #include <mach/regs-gpio.h>
#include <linux/cdev.h>
//-------------class_create,device_create------
#include <linux/device.h> /*用udev机制自动添加设备节点*/
struct class *led_class; static int led_major = ; /* 主设备号 */
static struct cdev LedDevs; /* 应用程序执行ioctl(fd, cmd, arg)时的第2个参数 */
#define LED_MAGIC 'k'
#define IOCTL_LED_ON _IOW (LED_MAGIC, 1, int)
#define IOCTL_LED_OFF _IOW (LED_MAGIC, 2, int)
#define IOCTL_LED_RUN _IOW (LED_MAGIC, 3, int)
#define IOCTL_LED_SHINE _IOW (LED_MAGIC, 4, int)
#define IOCTL_LED_ALLON _IOW (LED_MAGIC, 5, int)
#define IOCTL_LED_ALLOFF _IOW (LED_MAGIC, 6, int) /* 用来指定LED所用的GPIO引脚 */
static unsigned long led_table [] = {
S5PV210_MP04(),
S5PV210_MP04(),
S5PV210_MP04(),
S5PV210_MP04(), };
#define LED_NUM ARRAY_SIZE(led_table) /* 应用程序对设备文件/dev/led执行open(...)时，
* 就会调用leds_open函数
*/
static int leds_open(struct inode *inode, struct file *file)
{
int i;
for (i = ; i < ; i++) {
// 设置GPIO引脚的功能：本驱动中LED所涉及的GPIO引脚设为输出功能
s3c_gpio_cfgpin(led_table[i], S3C_GPIO_OUTPUT);
}
return ;
} //LEDS all light on
static void leds_all_on()
{
int i;
for (i=; i<; i++) {
gpio_set_value(led_table[i], );
}
} //LEDs all light off
static void leds_all_off()
{
int i;
for (i=; i<; i++) {
gpio_set_value(led_table[i], );
}
} /* 应用程序对设备文件/dev/leds执行ioctl(...)时，
* 就会调用leds_ioctl函数
*/
static int leds_ioctl(struct file *file,
unsigned int cmd,
unsigned long arg)//没有inode，用邋unlocked_ioctl
{
printk("in the leds_ioctl!!\n"); // if (__get_user(data, (unsigned int __user *)arg)) //方法二:指针参数传递
// return -EFAULT;
printk("arg is %d!!\n",arg); switch(cmd) {
case IOCTL_LED_ON:
printk("in the IOCTL_LED_ON!!\n");
// 设置指定引脚的输出电平为0
gpio_set_value(led_table[arg], );
break; case IOCTL_LED_OFF:
printk("in the IOCTL_LED_OFF!!\n");
// 设置指定引脚的输出电平为1
gpio_set_value(led_table[arg], );
break; case IOCTL_LED_RUN:
// 跑马灯
{
printk("in the IOCTL_LED_RUN!!\n");
int i,j;
leds_all_off();
//printk("IOCTL_LED_RUN");
for (i=;i<arg;i++)
for (j=;j<;j++) {
gpio_set_value(led_table[j], );
mdelay(); //delay 400ms
gpio_set_value(led_table[j], );
mdelay(); //delay 400ms
}
break;
} case IOCTL_LED_SHINE:
// LED 闪烁
{
printk("in the IOCTL_LED_SHINE!!\n");
int i,j;
leds_all_off();
printk("IOCTL_LED_SHINE\n");
for (i=;i<arg;i++) {
for (j=;j<;j++)
gpio_set_value(led_table[j], );
mdelay(); //delay 400ms
for (j=;j<;j++)
gpio_set_value(led_table[j], );
mdelay();
}
break ;
}
case IOCTL_LED_ALLON:
printk("in the IOCTL_LED_ALLON!!\n");
// 设置指定引脚的输出电平为0
leds_all_on();
break;
case IOCTL_LED_ALLOFF:
printk("in the IOCTL_LED_ALLOFF!!\n");
// 设置指定引脚的输出电平为1
leds_all_off();
break; default:
printk("in the default!!\n");
return -EINVAL;
}
return ;
} /* 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 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 = leds_open,
.unlocked_ioctl = leds_ioctl,
}; /*
* Set up the cdev structure for a device.
*/
static void led_setup_cdev(struct cdev *dev, int minor,
struct file_operations *fops)
{
int err, devno = MKDEV(led_major, minor); cdev_init(dev, fops);
dev->owner = THIS_MODULE;
dev->ops = fops;
err = cdev_add (dev, devno, );
/* Fail gracefully if need be */
if (err)
printk (KERN_NOTICE "Error %d adding Led%d", err, minor);
} /*
* 执行“insmod leds.ko”命令时就会调用这个函数
*/ static int __init leds_init(void) {
int result;
dev_t dev = MKDEV(led_major, );
char dev_name[]="led"; /* 加载模式后，执行”cat /proc/devices”命令看到的设备名称 */ /*gpio_request*/
int i,ret;
for (i = ; i < LED_NUM; i++)
{ ret=gpio_request(led_table[i],"LED");
if(ret)//注意，是ret
{
printk("%s:request GPIO %d for LED failed,ret= %d\n",dev_name,led_table[i],ret);
return ret;
}
s3c_gpio_cfgpin(led_table[i],S3C_GPIO_SFN());//output
gpio_set_value(led_table[i],);
} /* Figure out our device number. */
if (led_major)
result = register_chrdev_region(dev, , dev_name);
else {
result = alloc_chrdev_region(&dev, , , dev_name);
led_major = MAJOR(dev);
}
if (result < ) {
printk(KERN_WARNING "leds: unable to get major %d\n", led_major);
return result;
}
if (led_major == )
led_major = result; /* Now set up cdev. */
led_setup_cdev(&LedDevs, , &leds_fops); /*udev机制可以自动添加设备节点，只需要添加xxx_class这个类，以及device_create()*/
led_class = class_create(THIS_MODULE, "led_class");/*在sys目录下创建xx_class这个类,/sys/class/~*/
device_create(led_class, NULL, LedDevs.dev, dev_name, dev_name);/*自动创建设备/dev/$DEVICE_NAME*/ printk("Led device installed, with major %d\n", led_major);
printk("The device name is: %s\n", dev_name);
return ; } /*
* 执行”rmmod leds”命令时就会调用这个函数
*/
static void __exit leds_exit(void)
{
/*gpio_free*/
int i;
for (i = ; i < LED_NUM; i++)
{ gpio_free(led_table[i]);
} /* 卸载驱动程序 */
cdev_del(&LedDevs);
unregister_chrdev_region(MKDEV(led_major, ), );
printk("Led device uninstalled\n");
} /* 这两行指定驱动程序的初始化函数和卸载函数 */
module_init(leds_init);
module_exit(leds_exit); /* 描述驱动程序的一些信息，不是必须的 */
MODULE_AUTHOR(""); // 驱动程序的作者
MODULE_DESCRIPTION("LED Driver"); // 一些描述信息
MODULE_LICENSE("Dual BSD/GPL"); // 遵循的协议
测试代码：
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h> #define LED_MAGIC 'k'
#define IOCTL_LED_ON _IOW (LED_MAGIC, 1, int)
#define IOCTL_LED_OFF _IOW (LED_MAGIC, 2, int)
#define IOCTL_LED_RUN _IOW (LED_MAGIC, 3, int)
#define IOCTL_LED_SHINE _IOW (LED_MAGIC, 4, int)
#define IOCTL_LED_ALLON _IOW (LED_MAGIC, 5, int)
#define IOCTL_LED_ALLOFF _IOW (LED_MAGIC, 6, int) /*
led_test on //对应四个LED全亮
led_test off // 对应四个LED全灭
led_test run // 运行跑马灯实验
led_test shine //4个LED灯全灭、全亮交替闪烁 led_test 1 on //对应LED1点亮
led_test 1 off // 对应LED1熄灭
...
led_test 4 on //对应LED4点亮
led_test 4 off // 对应LED4熄灭 */
void usage(char *exename)
{
printf("Usage:\n");
printf(" %s <led_no> <on/off>\n", exename);
printf(" led_no = 1, 2, 3 or 4\n");
} int main(int argc, char **argv)
{
unsigned int led_no;
int fd = -;
unsigned int count=; if (argc > || argc == )
goto err; fd = open("/dev/led", ); // 打开设备
if (fd < ) {
printf("Can't open /dev/led\n");
return -;
} if (argc == ) {
if (!strcmp(argv[], "on")) {
ioctl(fd, IOCTL_LED_ALLON, count); // 点亮它
} else if (!strcmp(argv[], "off")) {
ioctl(fd, IOCTL_LED_ALLOFF, count); // 熄灭它
} else if (!strcmp(argv[], "run")) {
ioctl(fd, IOCTL_LED_RUN, count); //运行跑马灯
} else if (!strcmp(argv[], "shine")) {
ioctl(fd, IOCTL_LED_SHINE, count); //闪烁
} else {
goto err;
}
} if (argc == ) {
led_no = atoi(argv[]); // 操作哪个LED？
if (led_no > )
goto err;
if (!strcmp(argv[], "on")) {
ioctl(fd, IOCTL_LED_ON, led_no); // 点亮
} else if (!strcmp(argv[], "off")) {
ioctl(fd, IOCTL_LED_OFF, led_no); // 熄灭
} else {
goto err;
}
} close(fd);
return ; err:
if (fd > )
close(fd);
usage(argv[]);
return -; }