#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ide.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/gpio.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <asm/mach/map.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/irq.h>
static unsigned long flag = 0;
/*设备struct*/
struct led_struct
{
dev_t led_dev;
struct cdev led_cdev;
struct class *led_class;
struct device *led_device;
struct fasync_struct *sigio_list;
struct device_node *led_nd;
};
struct led_struct led_struct;
ssize_t read_flag(struct device *dev,struct device_attribute *attr,char *buf){
size_t count = 0;
count += sprintf(&buf[count],"%lu\n",flag);
return count;
}
ssize_t write_flag(struct device * dev,struct device_attribute *attr,char *buf,size_t count){
flag = buf[0] - '0';
//给所有以FASYNC标志调用fcntl的应用程序发信号
kill_fasync(&led_struct.sigio_list,SIGIO,POLL_IN);
return count;
}
struct device_attribute flag_attr = __ATTR(flag,S_IRUGO | S_IWUSR,read_flag,write_flag);
int led_open(struct inode *inode, struct file *filp)//打开led
{
printk("_____%s_____\n",__FUNCTION__);
return 0;
}
int led_fasync (int fd, struct file *filp, int onflag){
//将需要通知的迸程加入sigio_list链表或者从链表中移除
return fasync_helper(fd, filp, onflag, &led_struct.sigio_list);
}
static struct file_operations led_ops = {
.owner = THIS_MODULE,
.open = led_open,
.fasync = led_fasync,
};
static int __init led_init(void)
{
int ret = 0;
// 1.分配设备号
alloc_chrdev_region(&led_struct.led_dev, 0, 1, "my_led");
//2.创造cdev对象和file_operation,然后cdev_init初始化
cdev_init(&led_struct.led_cdev, &led_ops);
//3.cdev_add将cdev对象注册进入内核
cdev_add(&led_struct.led_cdev, led_struct.led_dev, 1);
//4.创造class与device
led_struct.led_class = class_create(THIS_MODULE, "led_class");
led_struct.led_device=device_create(led_struct.led_class, NULL, led_struct.led_dev, NULL, "led");
//在文件系统中创建一个名为"flag的文件
ret = device_create_file(led_struct.led_device,&flag_attr);
printk("flag = %d\n",flag);
return ret;
}
static void __exit led_exit(void)
{
printk("flag = %d\n",flag);
device_destroy(led_struct.led_class, led_struct.led_dev);
class_destroy(led_struct.led_class);
cdev_del(&led_struct.led_cdev);
unregister_chrdev_region(led_struct.led_dev, 1);
}
module_init(led_init);
module_exit(led_exit);
MODULE_LICENSE("GPL");
