编写LED灯的驱动，在应用程序中编写控制LED灯亮灭的代码逻辑实现LED灯功能的控制；
LED1->PE10 LED1亮灭：
RCC寄存器[4]->1 0X50000A28
GPIOE_MODER[21:20]->01 (输出) 0X50006000
GPIOE_ODR[10]->1(输出高电平) 0（输出低电平）0X50006014
LED2->PF10 LED2亮灭：
RCC寄存器[5]->1 0X50000A28
GPIOE_MODER[21:20]->01 (输出) 0X50006000
GPIOE_ODR[10]->1(输出高电平) 0（输出低电平）0X50006014
LED3->PE8 LED3亮灭：
RCC寄存器[4]->1 0X50000A28
GPIOE_MODER[17:16]->01 (输出) 0X50006000
GPIOE_ODR[8]->1(输出高电平) 0（输出低电平）0X50006014
GPIOE_OTYPER默认为00
GPIOE_PUPDR默认为0
GPIOE_OSPEEDR默认为00
注册cdev对象
---Makefile---工程管理文件
modname?=demo
arch?=arm
ifeq ($(arch),arm)
KERNELDIR:= /home/ubuntu/FSMP1A/linux-stm32mp-5.10.61-stm32mp-r2-r0/linux-5.10.61 #编译生成ARM架构
else
KERNELDIR:=/lib/modules/$(shell uname -r)/build #编译生成X86架构
endif
PWD:=$(shell pwd) #模块化编译文件路径
all:
make -C $(KERNELDIR) M=$(PWD) modules
clean:
make -C $(KERNELDIR) M=$(PWD) clean
obj-m:=$(modname).o
---head.h---头文件
#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;
//LED1和LED3寄存器地址
#define LED1_ADDR 0x50006000
#define LED2_ADDR 0x50007000
#define LED3_ADDR 0x50006000
#define RCC_ADDR 0x50000A28
//构建LED开关功能码,不添加ioctl第三个参数
#define LED_ON _IO('l',1)
#define LED_OFF _IO('l',0)
#endif---cdev.c---驱动程序
#include <linux/init.h>
#include <linux/module.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include "head.h"
#include <linux/io.h>
struct cdev *cdev = NULL;
unsigned major = 0;
unsigned minor = 0;
module_param(major, uint, 0664); // 方便再命令行传递major的值
dev_t devno;
struct class *cls;
struct device *dev;
char kbuf[128] = {0};
gpio_t *vir_led1;
gpio_t *vir_led2;
gpio_t *vir_led3;
unsigned int *vir_rcc;
// 封装操作方法
int mycdev_open(struct inode *inode, struct file *file)
{
// 设备文件和设备的绑定
// 根据打开的文件对应的设备号获取 次设备号
int min = MINOR(inode->i_rdev);
file->private_data = (void *)min;
printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
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 |= (0x1 << 10);
break;
case LED_OFF: // 关灯
vir_led1->ODR &= (~(0x1 << 10));
break;
}
break;
case 2: // 控制LED2
switch (cmd)
{
case LED_ON: // 开灯
vir_led2->ODR |= (0x1 << 10);
break;
case LED_OFF: // 关灯
vir_led2->ODR &= (~(0x1 << 10));
break;
}
break;
case 3: // 控制LED3
switch (cmd)
{
case LED_ON: // 开灯
vir_led3->ODR |= (0x1 << 8);
break;
case LED_OFF: // 关灯
vir_led3->ODR &= (~(0x1 << 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,
.unlocked_ioctl = mycdev_ioctl,
.release = mycdev_close,
};
// 相关寄存器地址映射及初始化
int all_led_init(void)
{
// 相关寄存器的内存映射
vir_led1 = ioremap(LED1_ADDR, sizeof(gpio_t));
if (vir_led1 == NULL)
{
printk("物理内存映射失败%d\n", __LINE__);
return -ENOMEM;
}
vir_led2 = ioremap(LED2_ADDR, sizeof(gpio_t));
if (vir_led2 == NULL)
{
printk("物理内存映射失败%d\n", __LINE__);
return -ENOMEM;
}
vir_led3 = vir_led1;
vir_rcc = ioremap(RCC_ADDR, 4);
if (vir_rcc == NULL)
{
printk("物理内存映射失败%d\n", __LINE__);
return -ENOMEM;
}
printk("寄存器内存映射成功\n");
// 硬件寄存器的初始化
(*vir_rcc) |= (0x3 << 4);
// LED1
vir_led1->MODER &= (~(0x3 << 20));
vir_led1->MODER |= (0x1 << 20);
vir_led1->ODR &= (~(0x1 << 10));
// LED2
vir_led2->MODER &= (~(0x3 << 20));
vir_led2->MODER |= (0x1 << 20);
vir_led2->ODR &= (~(0x1 << 10));
// LED3
vir_led3->MODER &= (~(0x3 << 16));
vir_led3->MODER |= (0x1 << 16);
vir_led3->ODR &= (~(0x1 << 8));
printk("寄存器初始化成功\n");
return 0;
}
static int __init mycdev_init(void)
{
int ret;
// 分配字符设备驱动对象空间
cdev = cdev_alloc();
if (cdev == NULL)
{
printk("字符设备驱动对象申请空间失败\n");
ret = -EFAULT;
goto out1;
}
printk("字符设备驱动对象申请空间成功\n");
// 字符设备驱动对象初始化
cdev_init(cdev, &fops);
// 设备号的申请
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) 动态申请设备号
{
ret = alloc_chrdev_region(&devno, minor, 3, "myled");
if (ret)
{
printk("静态申请设备号失败\n");
goto out2;
}
major = MAJOR(devno);
minor = MINOR(devno);
}
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");
相关寄存器地址映射及初始化
all_led_init();
// 向上提交目录信息
cls = class_create(THIS_MODULE, "myled");
if (IS_ERR(cls))
{
printk("向上提交目录信息失败\n");
ret = -PTR_ERR(cls);
goto out4;
}
printk("向上提交目录信息成功\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("向上提交设备节点信息成功\n");
return 0;
out5:
// 释放前一次提交的设备信息
for (--i; i >= 0; i--)
{
device_destroy(cls, MKDEV(major, i));
}
class_destroy(cls); // 释放目录信息
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);
// 释放申请的设备号和设备资源
unregister_chrdev_region(MKDEV(major, minor), 3);
// 释放字符设备驱动对象空间
kfree(cdev);
// 取消物理内存的映射
iounmap(vir_led1);
iounmap(vir_led2);
iounmap(vir_rcc);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");---test.c---应用程序测试程序
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include "head.h"
#include <sys/ioctl.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("设备文件打开失败\n");
exit(-1);
}
while (1)
{
printf("请输入对LED灯的控制：1(开灯) 0(关灯)>> ");
scanf("%d",&a);
getchar();
switch (a)
{
case 1:
ioctl(fd, LED_ON); // 第三个参数为指针
break;
case 0:
ioctl(fd, LED_OFF);
break;
}
}
close(fd);
return 0;
}
int fd = open("/dev/myled0", O_RDWR);
测试程序中只打开一个设备文件，对应LED1的次设备号，所以只控制LED1灯的亮灭
