beep实验
1.设备树代码
2.驱动代码
#include
#include
#include
#include
#include
#include
#include
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#include
#include
#define BEEP_CNT 1
#define BEEP_NAME "beep"
#define BEEPOFF 0 /* 关闭蜂鸣器 */
#define BEEPON 1 /* 打开蜂鸣器 */
/* beep设备结构体 */
struct beep_dev{
dev_t devid; /* 设备号 */
struct cdev cdev; /* 字符设备 */
struct class *class; /* 类 */
struct device *device; /* 设备 */
int major; /* 注设备号 */
int minor; /* 次设备号 */
struct device_node *nd; /* 设备节点 */
int beep_gpio; /* 设备树里面的编号 */
};
struct beep_dev beep; /* 定义LED结构体 */
void led_switch(struct beep_dev *dev, u8 sta)
{
if(sta == BEEPON) {
gpio_set_value(dev->beep_gpio, 0);
}else if(sta == BEEPOFF) {
gpio_set_value(dev->beep_gpio, 1);
} else {
printk("Error Number! \r\n");
}
}
static int beep_open(struct inode *inode, struct file *filp)
{
filp->private_data = &beep;
return 0;
}
static int beep_release(struct inode *inode, struct file *filp)
{
//struct beep_dev *dev = (struct beep_dev *)filp->private_data;
return 0;
}
static ssize_t beep_write(struct file *filp, const char __user *buf, size_t count, loff_t *ppos)
{
int retvalue;
unsigned char databuf[1];
// unsigned char ledstat;
struct beep_dev *dev = (struct beep_dev *)filp->private_data;
retvalue = copy_from_user(databuf, buf, count);
if(retvalue < 0) {
printk("kernel write failed!\r\n");
return -EFAULT;
}
led_switch(dev, databuf[0]);
return 0;
}
static ssize_t beep_read(struct file *filp, char __user *buf,
size_t cnt, loff_t *offt)
{
return 0;
}
/* 字符设备操作集 */
static const struct file_operations beep_fops = {
.owner = THIS_MODULE,
.write = beep_write,
.open = beep_open,
.read = beep_read,
.release = beep_release,
};
/* 模块入口函数 */
static int __init beep_init(void)
{
/* 定义一些所需变量 */
int ret = 0;
/* 1. 注册字符设备驱动 */
beep.major = 0;
if(beep.major) {
beep.devid = MKDEV(beep.major, 0);
ret = register_chrdev_region(beep.devid, BEEP_CNT, BEEP_NAME);
} else {
alloc_chrdev_region(&beep.devid, 0, BEEP_CNT, BEEP_NAME);
beep.major = MAJOR(beep.devid);
beep.minor = MINOR(beep.devid);
}
if(ret < 0){
goto fail_devid;
}
printk("Make devid success! \r\n");
printk("major = %d, minor = %d \r\n", beep.major, beep.minor);
/* 2. 初始化cdev */
beep.cdev.owner = THIS_MODULE;
cdev_init(&beep.cdev, &beep_fops);
ret = cdev_add(&beep.cdev, beep.devid, BEEP_CNT);
if (ret < 0){
goto fail_cdev;
} else {
printk("Cdev add sucess! \r\n");
}
/* 3. 自动创建设备节点 */
beep.class = class_create(THIS_MODULE, BEEP_NAME);
if(IS_ERR(beep.class)) {
ret = PTR_ERR(beep.class);
goto fail_class;
} else {
printk("Class create sucess! \r\n");
}
beep.device = device_create(beep.class, NULL, beep.devid, NULL, BEEP_NAME);
if(IS_ERR(beep.device)) {
ret = PTR_ERR(beep.device);
goto fail_device;
} else {
printk("Device create sucess! \r\n");
}
/* 1. 获取设备节点 */
beep.nd = of_find_node_by_path("/beep");
if( beep.nd == NULL){
ret = -EINVAL;
printk("beep node can not found!\r\n");
goto fail_findnd;
}
/* 2. 获取设备所对应的gpio */
/* 注意第三个参数，因为只有一个索引，所以是0 */
beep.beep_gpio = of_get_named_gpio(beep.nd, "beep-gpios", 0);
if( beep.beep_gpio < 0) {
printk("Can't find beep gpio \r\n");
ret = -EINVAL;
goto fail_findnd;
}
printk("Beep gpio num = %d. \r\n", beep.beep_gpio);
/* 3. 获取到IO之后，申请IO */
/* 作用是申请之后，就能知道该IO是否被其他函数占用 */
/* 如果申请失败，说明被战用啦 */
/* 解决方法：1.搜索所需管脚 2.在搜索复用管脚，例如 &gpio1 3 */
ret = gpio_request(beep.beep_gpio, "beep-gpio");
if(ret) {
printk("Failed to request the beep gpio! \r\n");
ret = -EINVAL;
goto fail_findnd;
}
/* 4. 使用IO */
ret = gpio_direction_output(beep.beep_gpio, 1); /* 设置输出，默认高电平不点亮 */
if(ret < 0){
printk("Failed to set input or output! \r\n");
goto fail_set_output;
}
/* 5. 输出低电平，打开蜂鸣器 */
gpio_set_value(beep.beep_gpio, 0);
printk("beep init! \r\n");
return 0;
/* 错误处理 */
fail_set_output:
gpio_free(beep.beep_gpio);
fail_findnd:
device_destroy(beep.class, beep.devid);
fail_device:
class_destroy(beep.class);
fail_class:
cdev_del(&beep.cdev);
fail_cdev:
unregister_chrdev_region(beep.devid, BEEP_CNT);
fail_devid:
return ret;
}
/* 模块出口函数 */
static void __exit beep_exit(void)
{
/* 关灯 */
gpio_set_value(beep.beep_gpio, 1);
/* 1. 释放设备号 */
cdev_del(&beep.cdev);
/* 2. 注销设备号 */
unregister_chrdev_region(beep.devid, BEEP_CNT);
/* 3. 摧毁设备 */
device_destroy(beep.class, beep.devid);
/* 4.摧毁类 */
class_destroy(beep.class);
/* 释放IO， 和上面的申请IO对应 */
gpio_free(beep.beep_gpio);
printk("beep exit! \r\n");
}
/* 模块入口和出口注册 */
module_init(beep_init);
module_exit(beep_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Shao Zheming");
3.应用代码
#include
#include
#include
#include
#include
#include
#include
/*
* argc: 应用程序参数个数
* argv[]: 参数是什么，具体的参数，说明参数是字符串的形式
* .chrdevbaseApp <0:1> 0表示关灯，1表示开灯
* .chrdevbaseApp /dev/led 0 关灯
* .chrdevbaseApp /dev/led 1 开灯
* */
#define BEEPOFF 0 /* 关灯 */
#define BEEPON 1 /* 开灯 */
int main(int argc, char *argv[])
{
if(argc != 3)
{
printf("Error Usage!\r\n");
return -1;
}
char *filename;
int fd, retValue;
unsigned char dataBuf[1];
filename = argv[1];
fd = open(filename, O_RDWR);
if(fd < 0)
{
printf("file %s open failed! \r\n", filename);
return -1;
}
dataBuf[0] = atoi(argv[2]);
retValue = write(fd, dataBuf, sizeof(dataBuf));
if(retValue < 0){
printf("Led Control Failed \r\n");
close(fd);
return -1;
}
close(fd);
return 0;
}