字符设备驱动之LED-混杂设备驱动（misc）

misc_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> #include <linux/miscdevice.h> 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) {  /* 配置GPIO为输出引脚 */  *gpfcon &= ~0xff00;  *gpfcon |= 0x5500;  return 0; } ssize_t led_write(struct file *file, const char __user *buf, size_t size, loff_t *offset) {  char ker_buf[2];    /* 根据buf传入的值点/灭灯 */  /* buf[0] - 哪个灯, 0 - 第1个灯 */  /* buf[1] - 亮/灭 , 0 - 亮, 1 - 灭 */  if (size != 2)  {   return -EINVAL;  }  copy_from_user(ker_buf, buf, 2);    if (ker_buf[0] < 0 || ker_buf[0] > 3)   return -EINVAL;  if ((ker_buf[1] != 0) && (ker_buf[1] != 1))   return -EINVAL;  if (ker_buf[1])  {   // 灭灯   *gpfdat |= (1<<(ker_buf[0] + 4));  }  else  {   *gpfdat &= ~(1<<(ker_buf[0] + 4));  }    return 2; } /* buf[0] - led1,0亮, 1灭 */ /* buf[1] - led2,0亮, 1灭 */ /* buf[2] - led3,0亮, 1灭 */ /* buf[3] - led4,0亮, 1灭 */ ssize_t led_read(struct file *file, char __user *buf, size_t size, loff_t *offset) {  char ker_buf[4];  unsigned long val;  if (size != 4)   return -EINVAL;  val = *gpfdat;    ker_buf[0] = (val & (1<<4)) ? 1 : 0;  ker_buf[1] = (val & (1<<5)) ? 1 : 0;  ker_buf[2] = (val & (1<<6)) ? 1 : 0;  ker_buf[3] = (val & (1<<7)) ? 1 : 0;  copy_to_user(buf, ker_buf, 4);  return 4; } static const struct file_operations led_fops = {  .owner = THIS_MODULE,  .write = led_write,  .read   = led_read,  .open = led_open }; static struct miscdevice led_misc = {  .minor  = 140,  .name  = "led",  .fops  = &led_fops,  }; int led_init(void) {  misc_register(&led_misc);  gpfcon = ioremap(0x56000050, 8); /* 得到虚拟地址 */  gpfdat = gpfcon + 1;    return 0; } void led_exit(void) {  misc_deregister(&led_misc);  iounmap(gpfcon); } module_init(led_init); module_exit(led_exit); MODULE_LICENSE("GPL");

test.c

#include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> /* led_test <which> <on|off> *  led_test r  */ void print_usage(char *str) {  printf("Usage:\n");  printf("%s r : read status\n", str);  printf("%s <which> <on|off>\n", str);  printf("which = 0,1,2,3\n"); }   int main(int argc, char **argv) {  int fd;  char buf[4];  int ret;  int i;  if (argc != 3 && argc != 2)  {   print_usage(argv[0]);   return -1;  }  fd = open("/dev/led", O_RDWR);  if (fd < 0)  {   printf("can't open /dev/led\n");   return -1;  }  if (argc == 3)  {   buf[0] = strtoul(argv[1], NULL, 0);   if (strcmp(argv[2], "on") == 0)   {    buf[1] = 0;   }   else   {    buf[1] = 1;   }   ret = write(fd, buf, 2);   if (ret != 2)   {    printf("error!\n");    return -1;   }  }  else  {   if (strcmp(argv[1], "r") == 0)   {    ret = read(fd, buf, 4);    for (i = 0; i < 4; i++)    {     printf("led%d %s\n", i+1, buf[i] ? "off" : "on");    }   }  }    return 0; }