字符设备驱动-按键驱动

#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)

{

// 配置GPF0,2为输入引脚

*gpfcon &= ~((0x3<(0*2)) | (0x3<(2*2)));

// 配置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)

{

// 返回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，推向编译模块时自动创建的__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);

MODULE_LICENSE("GPL");

=================================================================================================

测试程序：

#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;

}