5.Linux按键驱动-fasync异步通知
1.使用流程
2.应用程序思路
2.1绑定信号和信号处理函数
#include <signal.h>
typedef void (*sighandler_t)(int);
sighandler_t signal(int signum, sighandler_t handler);
当应用程序收到SIGIO信号的时候, sig_func函数就会被调用，调用read函数读取按键的值。
2.2APP把自己的pid告诉驱动程序。
注意：
这里一定要使能异步通知，不然驱动中的
gpio_fasync不会设置button中的fa_file成员。
其次会导致kill_fasync不知道应用程序的PID,不知道将信号发送给哪一个进程。
3.驱动程序思路
4.程序
应用：
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <poll.h>
#include <signal.h>
static int fd;
/* 信号处理函数 */
static void sig_func(int sig)
{
int val;
int num;
read(fd,&val,4);
num = val >>8;
printf("get button: %d val = %d\n", num, val - num *(1 << 8));
}
int main(int argc, char** argv)
{
int val;
int num;
struct pollfd fds[1];
int timeout_ms = 5000;
int ret;
int flags;
/* 判断输入值是否合法 */
if(argc != 2)
{
printf("Usage ./button_app /dev/devname\n");
return -1;
}
fd = open(argv[1], O_RDONLY);
if (fd == -1)
{
printf("open err\n");
}
else
{
printf("open success\n");
}
/* 初始化文件监听描述符 */
fds[0].fd = fd;
fds[0].events = POLLIN;
/*绑定SIGIO和sig_func */
signal(SIGIO, sig_func);
/* APP把自己的pid告诉驱动 */
fcntl(fd, F_SETOWN, getpid());/* APP把自己的pid告诉驱动程序 */
flags = fcntl(fd,F_GETFL);/* 获得标志位 */
fcntl(fd, F_SETFL, flags | FASYNC);/* 使能异步通知 */
//printf("设置了FASYNC\n");
while(1)
{
printf("www.100ask.net \n");
sleep(2);
}
/*while(1)
{
ret = poll(fds, 1, timeout_ms);
if((ret == 1) && (fds[0].revents == POLLIN))
{
read(fd, &val, 4);
num = val >>8;
printf("get button: %d val = %d\n", num, val - num *(1 << 8));
}
else
{
printf("timeout\n");
}
}*/
close(fd);
return 0;
}
驱动：
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/tty.h>
#include <linux/kmod.h>
#include <linux/gfp.h>
#include <linux/gpio/consumer.h>
#include <linux/platform_device.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/fcntl.h>
/* 定义结构体来描述gpio */
struct gpio_key{
int gpio;
struct gpio_desc* gpiod;
int flag;
int irq;
};
/* 定义全局变量来存储设备树中的所有gpio节点信息 */
static struct gpio_key* gpio_keys_100ask;
/* 字符设备的主设备号 */
static unsigned int major = 0;
static struct class *gpio_class;
//static int g_key = 0;
/* 定义等待队列 */
static DECLARE_WAIT_QUEUE_HEAD(gpio_key_wait);
struct fasync_struct * button_fasync;
/* 环形缓冲区 */
#define BUF_LEN 128
static int g_keys[BUF_LEN];
static int r, w;
#define NEXT_POS(x) ((x+1) % BUF_LEN)
int is_key_buf_empty(void)
{
return (r == w);
}
int is_key_buf_full(void)
{
return (r == NEXT_POS(w));
}
void put_key(int key)
{
if (!is_key_buf_full())
{
g_keys[w] = key;
w = NEXT_POS(w);
}
}
int get_key(void)
{
int key = 0;
if (!is_key_buf_empty())
{
key = g_keys[r];
r = NEXT_POS(r);
}
return key;
}
static ssize_t gpio_read(struct file *fp, char __user *buf, size_t size, loff_t * offset)
{
int err;
int key;
wait_event_interruptible(gpio_key_wait, !is_key_buf_empty());
key = get_key();
//err = copy_to_user(buf, &g_key, 4);
err = copy_to_user(buf, &key, 4);
//g_key = 0;
//printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
return 4;
}
static unsigned int gpio_poll(struct file *fp, struct poll_table_struct *wait)
{
//printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
poll_wait(fp, &gpio_key_wait, wait);
return is_key_buf_empty() ? 0 : POLLIN | POLLRDNORM;
}
static int gpio_fasync(int fd , struct file *file, int on)
{
//printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
if (fasync_helper(fd, file, on, &button_fasync) >= 0)
{
return 0;
}
else
{
return -EIO;
}
}
static const struct file_operations gpio_fops = {
.owner = THIS_MODULE,
.read = gpio_read,
.poll = gpio_poll,
.fasync = gpio_fasync,
};
static irqreturn_t gpio_key_isr(int irq, void *dev_id)
{
struct gpio_key* gpio_key = dev_id;
int val;
int key;
val = gpio_get_value(gpio_key->gpio);
//printk("key %d %d\n", gpio_key->gpio, val);
//g_key = (gpio_key->gpio << 8) | val;
key = (gpio_key->gpio << 8) | val;
put_key(key);
wake_up_interruptible(&gpio_key_wait);
/* 发信号 */
kill_fasync(&button_fasync, SIGIO, POLL_IN);
//printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
return IRQ_HANDLED;
}
static int gpio_probe(struct platform_device *pdev)
{
int count, i;
struct device_node *node;
int err;
node = pdev->dev.of_node;
count = of_gpio_count(node);
if (!count)
{
printk("%s %s line %d, there isn't any gpio available\n", __FILE__, __FUNCTION__, __LINE__);
return -1;
}
/* 申请资源 */
gpio_keys_100ask = kzalloc(sizeof(struct gpio_key) * count, GFP_KERNEL);
if (!gpio_keys_100ask)
{
printk("kzalloc error\n");
return -1;
}
/* 获得资源 */
for (i = 0; i < count; i++)
{
gpio_keys_100ask[i].gpio = of_get_gpio(node, i);
if (gpio_keys_100ask[i].gpio < 0)
{
printk("%s %s line %d, of_get_gpio_flags fail\n", __FILE__, __FUNCTION__, __LINE__);
return -1;
}
gpio_keys_100ask[i].gpiod = gpio_to_desc(gpio_keys_100ask[i].gpio);
gpio_keys_100ask[i].irq = gpio_to_irq(gpio_keys_100ask[i].gpio);
/* 申请中断 */
err = request_irq(gpio_keys_100ask[i].irq, gpio_key_isr, IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, "test1_gpio_keys_100ask", &gpio_keys_100ask[i]);
if (err)
{
printk("request_irq err\n");
}
}
/* 注册字符设备 */
major = register_chrdev(major, "100ask_key", &gpio_fops);
if(major < 0)
{
printk("register_chrdev err'\n");
return -1;
}
/* 注册类 */
gpio_class = class_create(THIS_MODULE, "100ask_key_class");
/* 注册设备 */
device_create(gpio_class, NULL, MKDEV(major,0), NULL, "100ask_key_button");
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
return 0;
}
static int gpio_remove(struct platform_device *pdev)
{
int count, i;
struct device_node *node;
node = pdev->dev.of_node;
count = of_gpio_count(node);
device_destroy(gpio_class, MKDEV(major,0));
class_destroy(gpio_class);
unregister_chrdev(major, "100ask_key");
for (i = 0; i < count; i++)
{
free_irq(gpio_keys_100ask[i].irq, &gpio_keys_100ask[i]);
}
kfree(gpio_keys_100ask);
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
return 0;
}
/*
* 在设备树中添加的节点的compatible属性为："test1_100ask,test1_gpio_key"
*/
static const struct of_device_id gpio_key_of_match[] = {
{.compatible = "test1_100ask,test1_gpio_key"},
{/* 这里必须要有一个空项，表示结束 */}
};
static struct platform_driver gpio_driver = {
.driver = {
.name = "test1_gpio_keys_100ask",
.of_match_table = gpio_key_of_match,
},
.probe = gpio_probe,
.remove = gpio_remove,
};
/* 基于platform总线来实现这个程序 */
static int gpio_init(void)
{
int ret;
ret = platform_driver_register(&gpio_driver);
if (ret != 0)
{
printk("platform_driver_register err\n");
return -1;
}
else
{
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
}
return ret;
}
static void gpio_exit(void)
{
platform_driver_unregister(&gpio_driver);
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
}
module_init(gpio_init);
module_exit(gpio_exit);
MODULE_LICENSE("GPL");