我找不到这个函数的实现,你可以提供一些简单的代码示例嘛?
时间: 2024-03-20 13:40:55 浏览: 17
当然可以,下面是一个简单的驱动程序示例,它实现了一个名为 rtc_alarm 的设备驱动程序,用来设置和获取闹钟时间。它包含了一个 `rtc_alarm_ioctl` 函数,用来处理 `RTC_WKALM_SET` 命令:
```c
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <asm/uaccess.h>
#include <linux/ioctl.h>
#include <linux/rtc.h>
#define RTC_ALARM_DEV_NAME "rtc_alarm"
#define RTC_ALARM_IOCTL_MAGIC 'p'
#define RTC_WKALM_SET _IOW(RTC_ALARM_IOCTL_MAGIC, 0x0f, struct rtc_wkalrm)
#define RTC_WKALM_READ _IOR(RTC_ALARM_IOCTL_MAGIC, 0x10, struct rtc_wkalrm)
static int rtc_alarm_open(struct inode *inode, struct file *filp)
{
printk(KERN_INFO "rtc_alarm: device opened\n");
return 0;
}
static int rtc_alarm_release(struct inode *inode, struct file *filp)
{
printk(KERN_INFO "rtc_alarm: device closed\n");
return 0;
}
static long rtc_alarm_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct rtc_wkalrm rtc_alarm;
switch (cmd) {
case RTC_WKALM_SET:
if (copy_from_user(&rtc_alarm, (struct rtc_wkalrm *)arg, sizeof(struct rtc_wkalrm)))
return -EFAULT;
// TODO: set alarm time
printk(KERN_INFO "rtc_alarm: set alarm time to %ld\n", rtc_alarm.time);
return 0;
case RTC_WKALM_READ:
// TODO: get alarm time
rtc_alarm.time = 1234567890; // just for demo
if (copy_to_user((struct rtc_wkalrm *)arg, &rtc_alarm, sizeof(struct rtc_wkalrm)))
return -EFAULT;
printk(KERN_INFO "rtc_alarm: get alarm time %ld\n", rtc_alarm.time);
return 0;
default:
return -EINVAL;
}
}
static struct file_operations rtc_alarm_fops = {
.owner = THIS_MODULE,
.open = rtc_alarm_open,
.release = rtc_alarm_release,
.unlocked_ioctl = rtc_alarm_ioctl,
};
static dev_t rtc_alarm_dev;
static struct cdev *rtc_alarm_cdev;
static int __init rtc_alarm_init(void)
{
int ret;
printk(KERN_INFO "rtc_alarm: module loaded\n");
ret = alloc_chrdev_region(&rtc_alarm_dev, 0, 1, RTC_ALARM_DEV_NAME);
if (ret) {
printk(KERN_ERR "rtc_alarm: failed to allocate chrdev region\n");
return ret;
}
rtc_alarm_cdev = cdev_alloc();
if (!rtc_alarm_cdev) {
printk(KERN_ERR "rtc_alarm: failed to allocate cdev\n");
unregister_chrdev_region(rtc_alarm_dev, 1);
return -ENOMEM;
}
rtc_alarm_cdev->owner = THIS_MODULE;
rtc_alarm_cdev->ops = &rtc_alarm_fops;
ret = cdev_add(rtc_alarm_cdev, rtc_alarm_dev, 1);
if (ret) {
printk(KERN_ERR "rtc_alarm: failed to add cdev\n");
cdev_del(rtc_alarm_cdev);
unregister_chrdev_region(rtc_alarm_dev, 1);
return ret;
}
return 0;
}
static void __exit rtc_alarm_exit(void)
{
cdev_del(rtc_alarm_cdev);
unregister_chrdev_region(rtc_alarm_dev, 1);
printk(KERN_INFO "rtc_alarm: module unloaded\n");
}
module_init(rtc_alarm_init);
module_exit(rtc_alarm_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your name");
MODULE_DESCRIPTION("RTC alarm driver");
```
上面的代码中,我们定义了两个 ioctl 命令:`RTC_WKALM_SET` 和 `RTC_WKALM_READ`,分别用来设置和获取闹钟时间。在 `rtc_alarm_ioctl` 函数中,我们根据命令序号来进行不同的处理。对于 `RTC_WKALM_SET` 命令来说,我们从用户空间复制 `struct rtc_wkalrm` 结构体,获取用户设置的闹钟时间,然后在驱动程序中进行处理。对于 `RTC_WKALM_READ` 命令来说,我们通常是从硬件中读取当前的闹钟时间,然后将其写入 `struct rtc_wkalrm` 结构体,最后将这个结构体传递回用户空间。