linux驱动之poll机制 按键测试
驱动程序
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <asm/irq.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <mach/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
#include <linux/miscdevice.h>
#include <linux/mm.h>
#include <asm/io.h> //ioremap()
volatile unsigned long *gpfcon;
volatile unsigned long *gpfdat;
static DECLARE_WAIT_QUEUE_HEAD(button_waitq); //声明等待队列
/* 中断事件标志, 中断服务程序将它置1，poll_key_read将它清0 */
static volatile int ev_press = 0;
//引脚描述结构
struct pin_desc{
unsigned int pin;
unsigned int key_val;
};
/* 键值: 按下时, 0x01, 0x02, 0x03, 0x04 */
/* 键值: 松开时, 0x81, 0x82, 0x83, 0x84 */
static unsigned char key_val;
struct pin_desc pins_desc[4] = {
{S3C2410_GPF0, 0x01},
{S3C2410_GPF1, 0x02},
{S3C2410_GPF2, 0x03},
{S3C2410_GPF4, 0x04},
};
static unsigned poll_key_poll(struct file *file, poll_table *wait)
{
unsigned int mask = 0;
poll_wait(file, &button_waitq, wait); // 不会立即休眠,将进程放入等待队列 button_waitq
if (ev_press)
mask |= POLLIN | POLLRDNORM;
return mask; //如果没有按键按下，就返回 0 。就是系统调用 poll 的返回值
}
/*
* 确定按键值
*/
static irqreturn_t buttons_irq(int irq, void *dev_id)
{
struct pin_desc * pindesc = (struct pin_desc *)dev_id;
unsigned int pinval;
pinval = s3c2410_gpio_getpin(pindesc->pin);
if (pinval)
{
/* 松开 */
key_val = 0x80 | pindesc->key_val;
}
else
{
/* 按下 */
key_val = pindesc->key_val;
}
ev_press = 1; /* 表示中断发生了 */
wake_up_interruptible(&button_waitq); /* 唤醒休眠的进程 */
return IRQ_RETVAL(IRQ_HANDLED);
}
/*打开的时候注册中断*/
static int poll_key_open(struct inode *inode, struct file *file)
{
request_irq(IRQ_EINT0, buttons_irq, IRQ_TYPE_EDGE_BOTH, "S1", &pins_desc[0]);
request_irq(IRQ_EINT1, buttons_irq, IRQ_TYPE_EDGE_BOTH, "S2", &pins_desc[1]);
request_irq(IRQ_EINT2, buttons_irq, IRQ_TYPE_EDGE_BOTH, "S3", &pins_desc[2]);
request_irq(IRQ_EINT4, buttons_irq, IRQ_TYPE_EDGE_BOTH, "S4", &pins_desc[3]);
return 0;
}
ssize_t poll_key_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
if (size != sizeof(key_val))
return -EINVAL;
/* 如果没有按键动作, 休眠 */
wait_event_interruptible(button_waitq, ev_press);
/* 如果有按键动作, 返回键值 */
copy_to_user(buf, &key_val, sizeof(key_val));
ev_press = 0;
return 1;
}
int poll_key_close(struct inode *inode, struct file *file)
{
free_irq(IRQ_EINT0, &pins_desc[0]);
free_irq(IRQ_EINT1, &pins_desc[1]);
free_irq(IRQ_EINT2, &pins_desc[2]);
free_irq(IRQ_EINT4, &pins_desc[3]);
return 0;
}
static struct file_operations key_fops = {
.owner = THIS_MODULE, /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */
.open = poll_key_open,
.read = poll_key_read,
.release = poll_key_close,
.poll = poll_key_poll,
};
int major;
static int poll_key_init(void)
{
major = register_chrdev(0, "mykey", &key_fops);
gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);
gpfdat = gpfcon + 1;
printk("This is my poll_key_driver Loaded ---===>>> \n");
return 0;
}
static void poll_key_exit(void)
{
unregister_chrdev(major, "mykey");
printk("This is my pll_key_driver UN_Loaded ---===>>> \n");
iounmap(gpfcon);
}
module_init(poll_key_init);
module_exit(poll_key_exit);
MODULE_LICENSE("GPL");
测试程序
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <poll.h>
int main(int argc, char **argv)
{
int fd;
unsigned char key_val;
int ret;
struct pollfd fds[1];
fd = open("/dev/buttons", O_RDWR);
if (fd < 0)
{
printf("can't open!\n");
}
fds[0].fd = fd;
fds[0].events = POLLIN;
while (1)
{
ret = poll(fds, 1, 3000);
if (ret == 0)
{
printf("3S time out\n");
}
else
{
read(fd, &key_val, 1);
printf("key_val = 0x%x\n", key_val);
}
}
return 0;
}
Makefile还是依旧。。。改下名字即可
测试
安装
[root@EmbedSky /]# insmod mykey.ko
This is my poll_key_driver Loaded ---===>>>
创建节点
[root@EmbedSky /]# cat /proc/devices
Character devices:
1 mem
4 /dev/vc/0
4 tty
5 /dev/tty
5 /dev/console
5 /dev/ptmx
7 vcs
10 misc
13 input
14 sound
29 fb
81 video4linux
89 i2c
90 mtd
116 alsa
128 ptm
136 pts
180 usb
188 ttyUSB
189 usb_device
204 tq2440_serial
252 mykey 我们的驱动
253 usb_endpoint
254 rtc
Block devices:
[root@EmbedSky /]# mknod /dev/buttons c 252 0
运行测试
[root@EmbedSky /]# ./pollkeytest
key_val = 0x2 按键的反应
key_val = 0x82
key_val = 0x4
key_val = 0x84
key_val = 0x3
key_val = 0x83
key_val = 0x1
key_val = 0x1
key_val = 0x81
3S time out 不按键会时间溢出
3S time out
3S time out
^C
[root@EmbedSky /]#