求助！更改驱动程序，将控制由ioctl 形式改为write形式，并添加read接口，通过read可获取LED 状态。
驱动程序：修改ioctl为write和read方法#include <linux/config.h> #include <linux/module.h> #include <linux/kernel.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/devfs_fs_kernel.h> #include <linux/miscdevice.h> #include <linux/delay.h> #include <asm/irq.h> #include <asm/io.h> #include <asm/arch/regs-gpio.h> #include <asm/hardware.h> #define DEVICE_NAME "led" #define LED_MAJOR 231 #define LED_BASE (0xE1180000) static int eduk4_led_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg{ unsigned char status; switch(cmd) { case 0: case 1: if (arg > 4) { return -EINVAL; } status = inb(LED_BASE); if(0 == cmd){ status &= ~(0x1 << arg); }else if(1 == cmd){ status |= (0x1 << arg); } outb(status, LED_BASE); return 0; default: return -EINVAL; } } static struct file_operations eduk4_led_fops = { .owner = THIS_MODULE, .ioctl = eduk4_led_ioctl, }; static int __init eduk4_led_init(void) { int ret; unsigned char status; ret = register_chrdev(LED_MAJOR, DEVICE_NAME, &eduk4_led_fops); if (ret < 0) { printk(DEVICE_NAME " can't register major number\n"); return ret; } devfs_mk_cdev(MKDEV(LED_MAJOR, 0), S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP, DEVICE_NAME); status = inb(LED_BASE); outb(status & 0xf0,LED_BASE); printk(DEVICE_NAME " initialized\n"); return 0; } static void __exit eduk4_led_exit(void) { unsigned char status; status = inb(LED_BASE); outb(status | 0x0f,LED_BASE); printk(DEVICE_NAME " remove\n"); devfs_remove(DEVICE_NAME); unregister_chrdev(LED_MAJOR, DEVICE_NAME); } module_init(eduk4_led_init); module_exit(eduk4_led_exit); MODULE_LICENSE("BSD/GPL"); 测试应用程序#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/ioctl.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/select.h> #include <sys/time.h> static int led_fd; int main(void) { // open device led_fd = open("/dev/led", 0); if (led_fd < 0) { if (led_fd < 0) { perror("open device led"); exit(1); } printf("Please look at the leds\n"); // led all off ioctl(led_fd, 1, 0); ioctl(led_fd, 1, 1); ioctl(led_fd, 1, 2); ioctl(led_fd, 1, 3); close(led_fd); return 0; }
loff_t *f_pos)
{
unsigned char status;
status = inb(LED_BASE);
if (copy_to_user(buf, &status, 1)) {
retval = -EFAULT;
goto out;
}
return 1;
out:
return 0;
}
static struct file_operations eduk4_led_fops = {
.owner = THIS_MODULE,
.read = eduk4_led_read,
.write = edu4_led_write,
};
static int __init eduk4_led_init(void)
{
int ret;
unsigned char status;
ret = register_chrdev(LED_MAJOR, DEVICE_NAME, &eduk4_led_fops);
if (ret < 0) {
printk(DEVICE_NAME " can't register major number\n");
return ret;
}
devfs_mk_cdev(MKDEV(LED_MAJOR, 0), S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP,
DEVICE_NAME);
status = inb(LED_BASE);
outb(status & 0xf0,LED_BASE);
printk(DEVICE_NAME " initialized\n");
return 0;
}
static void __exit eduk4_led_exit(void)
{
unsigned char status;
status = inb(LED_BASE);
outb(status | 0x0f,LED_BASE);
printk(DEVICE_NAME " remove\n");
devfs_remove(DEVICE_NAME);
unregister_chrdev(LED_MAJOR, DEVICE_NAME);
}
module_init(eduk4_led_init);
module_exit(eduk4_led_exit);
MODULE_LICENSE("BSD/GPL");
测试应用程序
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/select.h>
#include <sys/time.h>
static int led_fd;
int main(void)
{
unsigned char status;
unsigned char read_status;
// open device
led_fd = open("/dev/led", 0);
if (led_fd < 0) {
perror("open device led");
exit(1);
}
printf("Please look at the leds\n");
// led all off
status = 0xf;
write(led_fd, &status, sizeof(status));
read(led_fd, &read_status, 1);
printf("the leds status is %d \n", _read_status);
close(led_fd);
return 0;
}
大体上就是这样。