stm32字符设备驱动
时间: 2023-10-19 11:16:36 浏览: 54
在STM32上实现字符设备驱动需要以下步骤:
1.创建一个字符设备驱动程序,包括初始化和关闭函数。
2.注册字符设备驱动程序,使其在系统启动时自动加载。
3.实现字符设备驱动程序的读写函数,用于读写设备数据。
4.定义并初始化设备结构体及相关变量。
下面是一个简单的示例代码,实现在STM32上的字符设备驱动:
```
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <asm/uaccess.h>
#define DEVICE_NAME "mydevice"
#define DEVICE_CLASS "myclass"
static int major;
static struct class *myclass;
static struct device *mydevice;
static struct cdev mycdev;
static int mydevice_open(struct inode *inode, struct file *file)
{
printk(KERN_INFO "mydevice: Device opened\n");
return 0;
}
static int mydevice_release(struct inode *inode, struct file *file)
{
printk(KERN_INFO "mydevice: Device released\n");
return 0;
}
static ssize_t mydevice_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
{
char *data = "Hello world!\n";
int len = strlen(data);
if (count > len)
count = len;
if (copy_to_user(buf, data, count))
return -EFAULT;
*f_pos += count;
return count;
}
static ssize_t mydevice_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_pos)
{
char data[256];
if (count > 255)
count = 255;
if (copy_from_user(data, buf, count))
return -EFAULT;
data[count] = '\0';
printk(KERN_INFO "mydevice: Received %d bytes: %s\n", count, data);
*f_pos += count;
return count;
}
static struct file_operations mydevice_fops = {
.owner = THIS_MODULE,
.open = mydevice_open,
.release = mydevice_release,
.read = mydevice_read,
.write = mydevice_write,
};
static int __init mydevice_init(void)
{
int ret;
dev_t dev;
ret = alloc_chrdev_region(&dev, 0, 1, DEVICE_NAME);
if (ret < 0) {
printk(KERN_ERR "mydevice: Failed to allocate major number\n");
return ret;
}
major = MAJOR(dev);
cdev_init(&mycdev, &mydevice_fops);
mycdev.owner = THIS_MODULE;
ret = cdev_add(&mycdev, dev, 1);
if (ret < 0) {
printk(KERN_ERR "mydevice: Failed to add device\n");
unregister_chrdev_region(dev, 1);
return ret;
}
myclass = class_create(THIS_MODULE, DEVICE_CLASS);
if (IS_ERR(myclass)) {
printk(KERN_ERR "mydevice: Failed to create device class\n");
cdev_del(&mycdev);
unregister_chrdev_region(dev, 1);
return PTR_ERR(myclass);
}
mydevice = device_create(myclass, NULL, dev, NULL, DEVICE_NAME);
if (IS_ERR(mydevice)) {
printk(KERN_ERR "mydevice: Failed to create device\n");
class_destroy(myclass);
cdev_del(&mycdev);
unregister_chrdev_region(dev, 1);
return PTR_ERR(mydevice);
}
printk(KERN_INFO "mydevice: Device driver loaded\n");
return 0;
}
static void __exit mydevice_exit(void)
{
device_destroy(myclass, MKDEV(major, 0));
class_unregister(myclass);
class_destroy(myclass);
cdev_del(&mycdev);
unregister_chrdev_region(MKDEV(major, 0), 1);
printk(KERN_INFO "mydevice: Device driver unloaded\n");
}
module_init(mydevice_init);
module_exit(mydevice_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("STM32 Character Device Driver");
```
在上面的示例代码中,我们定义了一个名为“mydevice”的字符设备,它包括打开、关闭、读、写四个操作。在驱动程序的初始化函数中,我们使用`alloc_chrdev_region`函数来分配设备号,并使用`cdev_init`和`cdev_add`函数将设备与驱动程序关联起来。然后,我们使用`class_create`和`device_create`函数创建设备类和设备,并将它们与驱动程序关联起来。在驱动程序的退出函数中,我们使用`device_destroy`、`class_unregister`、`class_destroy`和`cdev_del`函数来删除设备和设备类,并释放设备号。
请注意,这只是一个简单的示例代码,仅供参考。在实际应用中,需要根据具体的需求来实现字符设备驱动程序。