字符设备驱动之LED

led.c

#include <linux/fs.h> #include <linux/module.h> #include <linux/errno.h> #include <linux/kernel.h> #include <linux/init.h> #include <linux/cdev.h> #include <linux/ioport.h> #include <linux/pci.h> #include <asm/uaccess.h> #include <asm/io.h> /* 次设备号:  *   0  - 所有的灯  *   1  - led1  *   2  - led2  *   3  - led3  *   4  - led4  */ static int major; static struct class *led_class; static volatile unsigned long * gpfcon; // = (volatile unsigned long *)0x56000050; static volatile unsigned long * gpfdat; // = (volatile unsigned long *)0x56000054; int led_open(struct inode *inode, struct file *file) {  int minor = iminor(inode);  if (minor > 4)   return -EINVAL;    /* 配置GPIO为输出引脚 */  if (minor == 0)  {   *gpfcon &= ~0xff00;     /*设置gpf4,5,6,7为输出引脚*/   *gpfcon |= 0x5500;  }  else  {   *gpfcon &= ~(0x3 << ((minor+3)*2)); /*否则单独设置某个引脚为输出功能*/   *gpfcon |= (0x1 << ((minor+3)*2));;  }  return 0; } ssize_t led_write(struct file *file, const char __user *buf, size_t size, loff_t *offset) {  char ker_buf[1];  int minor = iminor(file->f_path.dentry->d_inode);    /* 根据buf传入的值点/灭灯 */  /* buf[0] - 亮/灭 , 0 - 亮, 1 - 灭 */  if (size != 1)  {   return -EINVAL;  }  copy_from_user(ker_buf, buf, 1);    if ((ker_buf[0] != 0) && (ker_buf[0] != 1))   return -EINVAL;  if (minor == 0)  {   if (ker_buf[0])   {    // 全灭    *gpfdat |= (0xf<<4);   }   else   {    // 全亮    *gpfdat &= ~(0xf<<4);   }  }  else  {   if (ker_buf[0])   {    // 某个LED    *gpfdat |= (0x1<<(minor + 3));   }   else   {    // 某个LED    *gpfdat &= ~(0x1<<(minor + 3));   }  }    return 1; } static int led_ioctl(struct inode *inode, struct file *file, unsigned int cmd,unsigned long arg) {  unsigned int minor = iminor(inode);  if(minor>4)   return -1;  switch(cmd)  {   case 0:      if (minor == 0) {      printk("leds right all\n");（用于调试，在串口上能够观察执行到了这步没有）      // 全亮      *gpfdat &= ~(0xf<<4);     }     // 某个LED 亮     *gpfdat &= ~(0x1<<(minor + 3));     break;    case 1:     if (minor == 0) {       // 全灭         *gpfdat |= (0xf<<4);            }     // 某个LED 灭     printk("led off \n");     *gpfdat |= (0x1<<(minor + 3));     break;   default :     break;  }      return 0; } static const struct file_operations led_fops = {  .owner = THIS_MODULE,  .write = led_write,  .open = led_open,  .ioctl =led_ioctl, }; int led_init(void) {  int i;    major = register_chrdev(0, "led", &led_fops);  /* sysfs 自动创建设备节点 */  led_class = class_create(THIS_MODULE, "led_class");  class_device_create(led_class, NULL, MKDEV(major, 0), NULL, "leds"); // /dev/leds  for (i = 1; i <= 4; i++)   class_device_create(led_class, NULL, MKDEV(major, i), NULL, "led%d", i); // /dev/led1,2,3,4  gpfcon = ioremap(0x56000050, 8); /* 得到虚拟地址 */  gpfdat = gpfcon + 1;    return 0; } void led_exit(void) {  int i;  unregister_chrdev(major, "led");  for (i = 0; i <= 4; i++)   class_device_destroy(led_class, MKDEV(major, i));   class_destroy(led_class);  iounmap(gpfcon); } module_init(led_init); module_exit(led_exit); MODULE_LICENSE("GPL");

ioctl_test.c

#include <stdio.h> #include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> /* led_test <dev> <on|off>  * led_test /dev/leds on  * led_test /dev/led1 on  */ void print_usage(char *str) {  printf("Usage:\n");  printf("%s </dev/leds | /dev/ledN 1,2,3,4> <on|off>\n", str); } int main(int argc, char **argv) {  int fd;  char buf[2];  int ret;  int cmd;  if(argc!=3&&argc!=2)  {   print_usage(argv[0]);   return -1;  }  fd=open(argv[1],O_RDWR);  if(fd<0)  {   printf("can't open %s\n", argv[1]);   return -1;  }  if(strcmp(argv[2],"on")==0)  {     cmd=0;  }  else  {   cmd=1;  }   ret=ioctl(fd,cmd,NULL);  if(ret <0)   printf("error!\n");  return 0; }

write_test.c

#include <stdio.h> #include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> /* led_test <dev> <on|off>  * led_test /dev/leds on  * led_test /dev/led1 on  */ void print_usage(char *str) {  printf("Usage:\n");  printf("%s </dev/leds | /dev/ledN 1,2,3,4> <on|off>\n", str); } int main(int argc, char **argv) {  int fd;  char buf[1];  int ret;  if (argc != 3)  {   print_usage(argv[0]);   return -1;  }  fd = open(argv[1], O_RDWR);  if (fd < 0)  {   printf("can't open %s\n",argv[1]);   return -1;  }  if (strcmp(argv[2], "on") == 0)  {   buf[0] = 0;  }  else  {   buf[0] = 1;  }  ret = write(fd, buf, 1);  if (ret != 1)  {   printf("error!\n");   return -1;  }    return 0; }

简单的Makefile

all:     make -C /home/kernel/linux-2.6.22.6 M=`pwd` modules （前面是tab缩进哦） clean:     make -C /home/kernel/linux-2.6.22.6 M=`pwd` clean obj-m += led_drv.o

测试结果：

#insmod led.ko

#./ioctl
Usage:
./ioctl </dev/leds | /dev/ledN 1,2,3,4> <on|off>

#./ioctl /dev/leds on
leds right all

write测试也是没问题的。