#include “linux/module.h”
#include“linux/kernel.h”
#include“linux/fs.h”
#include“linux/init.h”
#include“linux/delay.h”
#include“asm/uaccess.h”
#include“asm/irq.h”
#include“asm/io.h”
#include“asm/arch/regs-gpio.h”
#include“asm/hardware.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;
static int key_drv_open(struct inode *inode, struct file *file)
{
// 装备GPF0,2为输入引脚
*gpfcon &= ~((0x3<<(0*2)) | (0x3<<(2*2)));
// 装备GPG3,11为输入引脚
*gpgcon &= ~((0x3<<(3*2)) | (0x3<<(11*2)));
return 0;
}
ssize_t key_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
// 回来4个引脚的电平
unsigned char key_vals[4];
int regval;
if(size != sizeof(key_vals))
return -EINVAL;
// 读GPF0,2
regval = *gpfdat;
key_vals[0] = (regval & (1<<0)) ? 1 : 0;
key_vals[1] = (regval & (1<<2)) ? 1 : 0;
// 读GPG3,11
regval = *gpgdat;
key_vals[2] = (regval & (1<<3)) ? 1 : 0;
key_vals[3] = (regval & (1<<11)) ? 1 : 0;
copy_to_user(buf, key_vals, sizeof(key_vals));
return sizeof(key_vals);
}
static struct file_operations key_drv_fops = {
.owner = THIS_MODULE, // 这是一个宏，面向编译模块时主动创立的__this_module变量
.open = key_drv_open,
.read = key_drv_read,
};
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_drv_init);
module_exit(key_drv_exit);
=================================================================================================
测验程序：
#include “sys/types.h”
#include “sys/stat.h”
#include “fcntl.h”
#include “stdio.h”
int main(int argc, char **argv)
{
int fd;
unsigned char key_vals[4];
fd = open(“/dev/buttons”, O_RDWR);
if(fd < 0)
printf(“cant open!\n”);
while(1)
{
read(fd, key_vals, sizeof(key_vals));
if (!key_vals[0] || !key_vals[1] || !key_vals[2] || !key_vals[3])
{
printf(“key pressed: %d %d %d %d\n”, key_vals[0], key_vals[1], key_vals[2], key_vals[3]);
}
}
return 0;
}
