驱动源码：
#include "linux/module.h"
#include "linux/kernel.h"
#include "linux/fs.h"
#include "linux/init.h"
#include "linux/delay.h"
#include "linux/irq.h"
#include "asm/uaccess.h"
#include "asm/irq.h"
#include "asm/io.h"
#include "asm/arch/regs-gpio.h"
#include "asm/hardware.h"
#include "linux/poll.h"
int major = 0;
static struct class *keydrv_class;
static struct class_device *keydrv_class_dev;
volatile unsigned long *gpfcon;
volatile unsigned long *gpfdat;
volatile unsigned long *gpgcon;
volatile unsigned long *gpgdat;
struct pin_desc{
unsigned int pin;
unsigned int key_val;
};
struct pin_desc pins_desc[4] = {
{S3C2410_GPF0, 0x01},
{S3C2410_GPF2, 0x02},
{S3C2410_GPG3, 0x03},
{S3C2410_GPG11, 0x04},
};
// 键值: 按下时, 0x01, 0x02, 0x03, 0x04
// 键值: 松开时, 0x81, 0x82, 0x83, 0x84
static unsigned char key_val;
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
// 中断事件标志, 中断服务程序将它置1，third_drv_read将它清0
static volatile int ev_press = 0;
static struct fasync_struct *button_async;
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
kill_fasync (&button_async, SIGIO, POLL_IN);
return IRQ_RETVAL(IRQ_HANDLED);
}
static int key_drv_open(struct inode *inode, struct file *file)
{
request_irq(IRQ_EINT0, buttons_irq,IRQT_BOTHEDGE,"S2",&pins_desc[0]);
request_irq(IRQ_EINT2, buttons_irq,IRQT_BOTHEDGE,"S3",&pins_desc[1]);
request_irq(IRQ_EINT11,buttons_irq,IRQT_BOTHEDGE,"S4",&pins_desc[2]);
request_irq(IRQ_EINT19,buttons_irq,IRQT_BOTHEDGE,"S5",&pins_desc[3]);
return 0;
}
ssize_t key_drv_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, 1);
ev_press = 0;
return 1;
}
int key_drv_close(struct inode *inode, struct file *file)
{
free_irq(IRQ_EINT0, &pins_desc[0]);
free_irq(IRQ_EINT2, &pins_desc[1]);
free_irq(IRQ_EINT11, &pins_desc[2]);
free_irq(IRQ_EINT19, &pins_desc[3]);
return 0;
}
static unsigned key_drv_poll(struct file *file, poll_table *wait)
{
unsigned int mask = 0;
poll_wait(file, &button_waitq, wait); // 不会立即休眠
if (ev_press)
mask |= POLLIN | POLLRDNORM;
return mask;
}
static int key_drv_fasync (int fd, struct file *filp, int on)
{
printk("driver: fifth_drv_fasync\n");
return fasync_helper(fd, filp, on, &button_async);
}
static struct file_operations key_drv_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 = key_drv_open,
.read = key_drv_read,
.release = key_drv_close,
.poll = key_drv_poll,
.fasync = key_drv_fasync,
};
static int key_drv_init(void)
{
major = register_chrdev(0, "key_drv", &key_drv_fops);
keydrv_class = class_create(THIS_MODULE, "key_drv");
keydrv_class_dev = class_device_create(keydrv_class, NULL, MKDEV(major, 0), NULL, "buttons");
gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);
gpfdat = gpfcon + 1;
gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16);
gpgdat = gpgcon + 1;
return 0;
}
static void key_drv_exit(void)
{
unregister_chrdev(major, "key_drv");
class_device_unregister(keydrv_class_dev);
class_destroy(keydrv_class);
iounmap(gpfcon);
iounmap(gpgcon);
return 0;
}
module_init(key
