通过字符设备驱动分步注册方式编写LED驱动，完成设备文件和设备的绑定
head.h
#ifndef __HEAD_H__
#define __HEAD_H__
typedef struct
{
unsigned int MODER;
unsigned int OTYPER;
unsigned int OSPEEDR;
unsigned int PUPDR;
unsigned int IDR;
unsigned int ODR;
} gpio_t;
#define PHY_LED1_ADDR 0X50006000
#define PHY_LED2_ADDR 0X50007000
#define PHY_LED3_ADDR 0X50006000
#define PHY_RCC_ADDR 0X50000A28
//构建LED开关的功能码，不添加ioctl第三个参数
#define LED_ON _IO('l', 1)
#define LED_OFF _IO('l', 0)
#endifmychrdev.c
#include
#include
#include
#include
#include
#include
#include
#include
#include "head.h"
struct cdev *cdev;
dev_t devno;
struct class *cls;
struct device *dev;
char kbuf[128] = {0};
unsigned int major = 0;
unsigned int minor = 0;
module_param(major, uint, 0664); // 方便在命令行传递参数
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
unsigned int *vir_rcc;
int mycdev_open(struct inode *inode, struct file *file)
{
int min = MINOR(inode->i_rdev); // 根据打开的文件对应的设备号获取次设备号
file->private_data = (void *)min;
printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
return 0;
}
ssize_t mycdev_read(struct file *file, char *ubuf, size_t size, loff_t *lof)
{
int ret;
ret = copy_to_user(ubuf, kbuf, size);
if (ret)
{
printk("copy_to_user err\n");
return -EIO;
}
return 0;
}
ssize_t mycdev_write(struct file *file, const char *ubuf, size_t size, loff_t *lof)
{
int ret;
// 从用户拷贝
ret = copy_from_user(kbuf, ubuf, size);
if (ret)
{
printk("copy_from_user err\n");
return -EIO;
}
return 0;
}
long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
int min = (int)file->private_data;
switch (min)
{
case 0: // 控制LED1
switch (cmd)
{
case LED_ON:
// 开灯
vir_led1->ODR |= 1 << 10;
break;
case LED_OFF:
// 关灯
vir_led1->ODR &= (~(1 << 10));
break;
}
break;
case 1: // 控制LED2
switch (cmd)
{
case LED_ON:
vir_led2->ODR |= 1 << 10;
// 开灯
break;
case LED_OFF:
// 关灯
vir_led2->ODR &= (~(1 << 10));
break;
}
break;
case 2: // 控制LED3
switch (cmd)
{
case LED_ON:
// 开灯
vir_led3->ODR |= 1 << 8;
break;
case LED_OFF:
// 关灯
vir_led3->ODR &= (~(1 << 8));
break;
}
break;
}
return 0;
}
int mycdev_close(struct inode *inode, struct file *file)
{
printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
return 0;
}
struct file_operations fops = {
.open = mycdev_open,
.write = mycdev_write,
.read = mycdev_read,
.unlocked_ioctl = mycdev_ioctl,
.release = mycdev_close,
};
int all_led_init(void)
{
// 寄存器地址的映射
vir_led1 = ioremap(PHY_LED1_ADDR, sizeof(gpio_t));
if (vir_led1 == NULL)
{
printk("ioremap filed：%d\n", __LINE__);
return -ENOMEM;
}
vir_led2 = ioremap(PHY_LED2_ADDR, sizeof(gpio_t));
if (vir_led2 == NULL)
{
printk("ioremap filed：%d\n", __LINE__);
return -ENOMEM;
}
vir_led3 = vir_led1;
vir_rcc = ioremap(PHY_RCC_ADDR, 4);
if (vir_rcc == NULL)
{
printk("ioremap filed：%d\n", __LINE__);
return -ENOMEM;
}
printk("物理地址映射成功\n");
// 寄存器的初始化
// rcc
(*vir_rcc) |= (0X3 << 4);
// led1
vir_led1->MODER &= (~(3 << 20));
vir_led1->MODER |= (1 << 20);
vir_led1->ODR &= (~(1 << 10));
// led2
vir_led2->MODER &= (~(3 << 20));
vir_led2->MODER |= (1 << 20);
vir_led2->ODR &= (~(1 << 10));
// led3
vir_led3->MODER &= (~(3 << 16));
vir_led1->MODER |= (1 << 16);
vir_led1->ODR &= (~(1 << 8));
printk("寄存器初始化成功\n");
return 0;
}
static int __init mycdev_init(void)
{
int ret;
// 为字符设备驱动对象申请空间
cdev = cdev_alloc();
if (!cdev)
{
printk("字符设备驱动对象申请空间失败\n");
ret = -EFAULT;
goto out1;
}
printk("申请设备空间成功\n");
// 初始化字符设备驱动对象
cdev_init(cdev, &fops);
// 申请设备号
if (major > 0) // 静态指定设备号
{
ret = register_chrdev_region(MKDEV(major, minor), 3, "myled");
if (ret)
{
printk("静态申请设备号失败\n");
goto out2;
}
}
else if (major == 0) // 动态指定
{
ret = alloc_chrdev_region(&devno, minor, 3, "myled");
if (ret)
{
printk("动态申请设备号失败\n");
goto out2;
}
major = MAJOR(devno); // 获取主设备号
minor = MINOR(devno); // 获取次设备号
}
printk("申请设备号成功\n");
// 注册字符设备驱动对象
ret = cdev_add(cdev, MKDEV(major, minor), 3);
if (ret)
{
printk("注册字符设备驱动对象失败\n");
goto out3;
}
printk("注册字符设备驱动对象成功\n");
// 寄存器映射以及初始化
all_led_init();
// 向上提交目录信息
cls = class_create(THIS_MODULE, "myled");
if (IS_ERR(cls))
{
printk("向上提交目录失败\n");
ret = -PTR_ERR(cls);
goto out4;
}
printk("向上提交目录成功\n");
// 向上提交设备节点信息
int i;
for (i = 0; i < 3; i++)
{
dev = device_create(cls, NULL, MKDEV(major, i), NULL, "myled%d", i);
if (IS_ERR(dev))
{
printk("向上提交设备节点信息失败\n");
ret = -PTR_ERR(dev);
goto out5;
}
}
printk("向上提交设备信息成功\n");
return 0;
out5:
// 释放前一次提交成功的设备信息
for (--i; i >= 0; i--)
{
device_destroy(cls, MKDEV(major, i));
}
class_destroy(cls); // 释放目录
out4:
cdev_del(cdev);
out3:
unregister_chrdev_region(MKDEV(major, minor), 3);
out2:
kfree(cdev);
out1:
return ret;
}
static void __exit mycdev_exit(void)
{
// 释放节点信息
int i;
for (i = 0; i < 3; i++)
{
device_destroy(cls, MKDEV(major, i));
}
// 销毁目录
class_destroy(cls);
// 注销驱动对象
cdev_del(cdev);
// 释放设备号
unregister_chrdev_region(MKDEV(major, minor), 3);
// 释放对象空间
kfree(cdev);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");
app.c
#include
#include
#include
#include
#include
#include
#include
#include
#include "head.h"
int main(int argc, char const *argv[])
{
int a;
char buf[128] = {0};
int fd = open("/dev/myled0", O_RDWR);
if (fd < 0)
{
printf("打开设备文件失败\n");
exit(-1);
}
while (1)
{
// 从终端读取
printf("请输入对LED灯的控制：1(开灯)0(关灯)>");
scanf("%d", &a);
switch (a)
{
case 1:
ioctl(fd, LED_ON); // 开灯
break;
case 0:
ioctl(fd, LED_OFF); // 关灯
break;
}
}
close(fd);
return 0;
}