虚拟键盘驱动程序

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文章出处： http://www.limodev.cn/blog
作者联系方式：李先静 <xianjimli at hotmail dot com>

前 段时间写一个程序，要向系统中注入按键事件，我又不想信赖于具体的GUI，就写一个虚拟键盘设备驱动程序，感觉挺好用的，不过后来发现linux其实有一 个uinput驱动程序实现了类似的功能。幸好后来才发现uinput这玩意儿，否则就没有机会去写了这个程序了，有时真是宁愿知识面窄一点，这样才有机 会重复发明一些轮子，从中获得一些乐趣。

o 先写一个字符驱动程序。

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/proc_fs.h>
#include <linux/fcntl.h>	
#include <linux/aio.h>
#include <asm/uaccess.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/input.h>
int vkeyboard_major = 201;
module_param(vkeyboard_major, int, 0);
MODULE_AUTHOR("Li XianJing <[email protected]>");
MODULE_LICENSE("GPL");
 
static struct input_dev* vkeyboard_idev = NULL;
 
int vkeyboard_open(struct inode* inode, struct file* filp)
{
	return 0;
}
 
int vkeyboard_release(struct inode* inode, struct file* filp)
{
	return 0;
}
 
ssize_t vkeyboard_read(struct file* filp, char __user *buf, size_t count, loff_t* f_pos)
{
	printk(KERN_INFO"%s/n", __func__);
	return count;
}
 
struct keyboard_event
{
	int press;
	int key;
};
 
ssize_t vkeyboard_write(struct file* filp, const char __user * buf, size_t count, loff_t* f_pos)
{
	int ret = 0;
	struct keyboard_event event;
 
	while(ret < count)
	{
		if(copy_from_user(&event, buf + ret, sizeof(event)))
		{
			return -EFAULT;
		}
		ret += sizeof(event);
 
		input_event(vkeyboard_idev, EV_MSC, MSC_SCAN, event.key);
		input_report_key(vkeyboard_idev, event.key, event.press);
		input_sync (vkeyboard_idev);
 
		printk(KERN_INFO"%s p=%d key=%d with scan code/n", __func__, event.press, event.key);
	}
 
	return ret;
}
 
static struct file_operations vkeyboard_fops = 
{
	.owner = THIS_MODULE,
	.open    = vkeyboard_open,
	.release = vkeyboard_release,
	.read    = vkeyboard_read,
	.write   = vkeyboard_write,
};
 
static int __init vkeyboard_init(void)
{
	int result = register_chrdev(vkeyboard_major, "vkeyboard", &vkeyboard_fops);
	vkeyboard_input_dev_setup();
 
	return result;
}
 
static void __exit vkeyboard_cleanup(void)
{
	input_unregister_device(vkeyboard_idev);
	unregister_chrdev(vkeyboard_major, "vkeyboard");
 
	return;
}
 
module_init(vkeyboard_init);
module_exit(vkeyboard_cleanup);

o 再实现一个虚拟输入设备。

static int vkeyboard_input_dev_open(struct input_dev* idev)
{
	printk(KERN_INFO"%s/n", __func__);
 
	return 0;
}
 
static void vkeyboard_input_dev_close(struct input_dev* idev)
{
	printk(KERN_INFO"%s/n", __func__);
 
	return;
}
 
static int vkeyboard_input_dev_setup(void)
{
	int ret = 0;
	int i = 0;
	vkeyboard_idev = input_allocate_device();
 
	if(vkeyboard_idev == NULL)
	{
		return -ENOMEM;
	}
 
    vkeyboard_idev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS) | BIT_MASK(EV_MSC);
	vkeyboard_idev->mscbit[0] = BIT_MASK(MSC_SCAN) | BIT_MASK(MSC_SERIAL) | BIT_MASK(MSC_RAW);
 
	bitmap_fill(vkeyboard_idev->keybit, KEY_MAX);
	bitmap_fill(vkeyboard_idev->relbit, REL_MAX);
	bitmap_fill(vkeyboard_idev->absbit, ABS_MAX);	            
 
	vkeyboard_idev->name = "vkeyboard";
	vkeyboard_idev->phys = "vkeyboard/input0";
	vkeyboard_idev->open = vkeyboard_input_dev_open;
	vkeyboard_idev->close = vkeyboard_input_dev_close;
 
	for(i = 32; i < KEY_MAX; i++)
	{
		input_set_capability(vkeyboard_idev, EV_KEY, i);
	}
	__set_bit(EV_KEY, vkeyboard_idev->evbit);
 
	ret = input_register_device(vkeyboard_idev);
 
	return ret;
}

o Makefile

obj-m := vkeyboard.o

KDIR := /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)

default:
	$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
install:
	$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules_install
clean:
	rm -f *.mod.c *.ko *.o Module.markers  modules.order  Module.symvers

加载模块后，向/dev/vkeyboard里写入要注入的事件，事件将会转发到/dev/input/eventX输入设备文件里，系统会从这里自动读取事件。