20231027 基于STM32mp157a 的内核与应用层通过子系统控制led灯，以及计时器功能-编程知识

1.基于GPIO子系统编写LED驱动，编写应用程序进行测试

stm32mp157a-fsmp1a.dts

内核程序：ledk.c

#include <linux/init.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/delay.h>
#include <linux/timer.h>struct device_node *dnode1;
struct gpio_desc *gpiono1;
struct gpio_desc *gpiono2;
struct gpio_desc *gpiono3;
struct timer_list mytimer;unsigned int *vir_rcc;
struct class *cls;
struct device *dev;
int major;char kbuf[128] = {0};//定义操作方法
int mycdev_open(struct inode *inode, struct file *file)
{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)
{printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);int ret1=copy_to_user(ubuf,kbuf,size);if(ret1){printk("copy_to_user filed\n");return -EIO;}return 0;
}
ssize_t mycdev_write(struct file *file, const char *ubuf, size_t size, loff_t *lof)
{printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);int ret=copy_from_user(kbuf,ubuf,size);if(ret){printk("copy_from_user filed\n");return -EIO;}//设定该GPIO管脚的输出值if(!strcmp(kbuf,"off")){gpiod_set_value(gpiono1,0);gpiod_set_value(gpiono2,0);gpiod_set_value(gpiono3,0);       }else if(!strcmp(kbuf,"on")){gpiod_set_value(gpiono1,1);gpiod_set_value(gpiono2,1);gpiod_set_value(gpiono3,1); }return 0;
}
int mycdev_close(struct inode *inode, struct file *file)
{printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);return 0;
}
//定义操作方法结构体变量并赋值
struct file_operations fops = {.open = mycdev_open,.read = mycdev_read,.write = mycdev_write,.release = mycdev_close,
};static int __init mycdev_init(void)
{// 字符设备驱动注册major = register_chrdev(0, "mychrdev", &fops);if (major < 0){printk("字符设备驱动注册失败\n");return major;}printk("字符设备驱动注册成功:major=%d\n", major);// 向上提交目录cls = class_create(THIS_MODULE, "mychrdev");if (IS_ERR(cls)){printk("向上提交目录失败\n");return -PTR_ERR(cls);}printk("向上提交目录成功\n");// 向上提交设备节点信息int i; // 向上提交三次设备节点信息for (i = 0; i < 3; i++){dev = device_create(cls, NULL, MKDEV(major, i), NULL, "myled%d", i);if (IS_ERR(dev)){printk("向上提交设备节点失败\n");return -PTR_ERR(dev);}}printk("向上提交设备节点成功\n");//解析设备树节点信息dnode1 = of_find_node_by_path("/myled");if(dnode1 == NULL){printk("path_find failed \n");return -ENXIO;}//根据GPIO相关节点得到GPIO编号gpiono1 = gpiod_get_from_of_node(dnode1,"led1-gpio",0,GPIOD_OUT_LOW,NULL);if(IS_ERR(gpiono1)){printk("申请gpiono1信息失败 \n");}printk("申请gpiono1信息成功 \n");gpiono2 = gpiod_get_from_of_node(dnode1,"led2-gpio",0,GPIOD_OUT_LOW,NULL);if(IS_ERR(gpiono2)){printk("申请gpiono2信息失败 \n");}printk("申请gpiono2信息成功 \n");gpiono3 = gpiod_get_from_of_node(dnode1,"led3-gpio",0,GPIOD_OUT_LOW,NULL);if(IS_ERR(gpiono3)){printk("申请gpiono3信息失败 \n");}printk("申请gpiono3信息成功 \n");//GPIO的状态return 0;
}
static void __exit mycdev_exit(void)
{//设定该GPIO管脚的输出值gpiod_set_value(gpiono1,0);gpiod_set_value(gpiono2,0);gpiod_set_value(gpiono3,0);//释放GPIO编号gpiod_put(gpiono1);gpiod_put(gpiono2);gpiod_put(gpiono3);// 销毁设备节点信息int i;for (i = 0; i < 3; i++){device_destroy(cls, MKDEV(major, i));}// 销毁目录class_destroy(cls);// 注销字符设备驱动unregister_chrdev(major, "mychrdev");}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

应用程序：ledu.c

#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>int main(int argc,const char * argv[])
{int a=0;char buf[128] = "";char buf1[128] = "";int fd1=open("/dev/myled0",O_RDWR);int fd2=open("/dev/myled1",O_RDWR);int fd3=open("/dev/myled2",O_RDWR);if(fd1<0){printf("打开设备文件1失败\n");exit(-1);}if(fd2<0){printf("打开设备文件2失败\n");exit(-1);}if(fd3<0){printf("打开设备文件3失败\n");exit(-1);}memset(buf,0,sizeof(buf));while(1){printf("请输入灯的控制(1开灯/0关灯) => ");scanf("%d",&a);write(fd1,buf,sizeof(buf));write(fd2,buf,sizeof(buf));write(fd3,buf,sizeof(buf));if(a == 1){strcpy(buf,"on");write(fd1,buf,sizeof(buf));write(fd2,buf,sizeof(buf));write(fd3,buf,sizeof(buf));            }else if(a == 0){strcpy(buf,"off");write(fd1,buf,sizeof(buf));write(fd2,buf,sizeof(buf));write(fd3,buf,sizeof(buf));             }read(fd1,buf1,sizeof(buf));printf("buf1:%s\n",buf1);}return 0;
}

2.设置定时器，5秒钟打印一次hello world

内核程序

#include <linux/init.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/delay.h>
#include <linux/timer.h>struct device_node *dnode1;
struct gpio_desc *gpiono1;
struct gpio_desc *gpiono2;
struct gpio_desc *gpiono3;
struct timer_list mytimer;char kbuf[128] = {0};void mytimer_funtion(struct timer_list *timer)
{//PRINTKprintk("阿巴阿巴阿巴阿巴阿巴\n");gpiod_set_value(gpiono1,!gpiod_get_value(gpiono1));//启用定时器mod_timer(timer,jiffies + msecs_to_jiffies(5000));
}static int __init mycdev_init(void)
{//解析设备树节点信息dnode1 = of_find_node_by_path("/myled");if(dnode1 == NULL){printk("path_find failed \n");return -ENXIO;}//根据GPIO相关节点得到GPIO编号gpiono1 = gpiod_get_from_of_node(dnode1,"led1-gpio",0,GPIOD_OUT_LOW,NULL);if(IS_ERR(gpiono1)){printk("申请gpiono1信息失败 \n");}gpiono2 = gpiod_get_from_of_node(dnode1,"led2-gpio",0,GPIOD_OUT_LOW,NULL);if(IS_ERR(gpiono2)){printk("申请gpiono2信息失败 \n");}gpiono3 = gpiod_get_from_of_node(dnode1,"led3-gpio",0,GPIOD_OUT_LOW,NULL);if(IS_ERR(gpiono3)){printk("申请gpiono3信息失败 \n");}//分配定时器对象(timer_list)//初始化定时器(timer_setup)timer_setup(&mytimer,mytimer_funtion,0);mytimer.expires = jiffies+HZ;//注册定时器并启用(add_timer)add_timer(&mytimer);//GPIO的状态return 0;
}
static void __exit mycdev_exit(void)
{//设定该GPIO管脚的输出值gpiod_set_value(gpiono1,0);gpiod_set_value(gpiono2,0);gpiod_set_value(gpiono3,0);//释放GPIO编号gpiod_put(gpiono1);gpiod_put(gpiono2);gpiod_put(gpiono3);//注销定时器(del_timer)del_timer(&mytimer);}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");