虚拟触摸屏驱动+如何通过启动参数给驱动程序传递参数

   该驱动可用于没有触摸屏的设备上，加上虚拟FrameBuffer驱动(vfb)就可以模拟触摸屏。比如在Android系统的移植中，系统要正常启动，就必须要有FrameBuffer驱动和声卡驱动，此二者可使用drivers/video/vfb.c和sound/drivers/dummy.c两个虚拟驱动代替，系统正常起来后，可使用加上虚拟触摸屏驱动，就可以使用android-vnc-server(http://code.google.com/p/android-vnc-server/)以启动VNC服务，然后使用VNC客户端将Android系统桌面显示到远端。配合虚拟触摸屏驱动，在远端就可以使用鼠标进行操作。

   由于触摸屏的大小参数必须和FrameBuffer的参数一致，所以驱动实现了使用启动参数传递大小参数，以此可作为如何通过启动参数给驱动程序传递参数的示例，代码如下：

1. /*
   
2.  * Virtual TouchScreen driver
   
3.  *
   
4.  * Copyright (C) 2011 Niu Tao <[e-mail]>
   
5.  *
   
6.  * This file is subject to the terms and conditions of the GNU General Public
   
7.  * License. See the file COPYING in the main directory of this archive for
   
8.  * more details.
   
9.  *
   
10.  */
    
11. 
    
12. #include <linux/module.h>
    
13. #include <linux/kernel.h>
    
14. #include <linux/init.h>
    
15. #include <linux/errno.h>
    
16. #include <linux/delay.h>
    
17. #include <linux/ioport.h>
    
18. #include <linux/interrupt.h>
    
19. #include <linux/input.h>
    
20. 
    
21. #define DRIVER_DESC "Virtual TouchScreen"
    
22. 
    
23. static struct input_dev *vts_dev;
    
24. 
    
25. #define VTS_MIN_XC 0
    
26. #define VTS_MAX_XC 320
    
27. #define VTS_MIN_YC 0
    
28. #define VTS_MAX_YC 480
    
29. 
    
30. static int __initdata vts_max_xc = VTS_MAX_XC;
    
31. static int __initdata vts_max_yc = VTS_MAX_YC;
    
32. 
    
33. #ifndef MODULE
    
34. static int __initdata vts_use = 0;
    
35. /**
    
36.  * parse options,format must be vts=widthxheigth
    
37.  */
    
38. static int __init vts_setup(char *str)
    
39. {
    
40.     char buf[64];
    
41.     char *p;
    
42.     int xc, yc;
    
43. 
    
44.     vts_use = 1;
    
45. 
    
46.     strncpy(buf, str, sizeof(buf));
    
47.     p = strchr(buf, 'x');
    
48.     if (!p)
    
49.         goto out;
    
50.     *p = '\0';
    
51.     xc = simple_strtoul(buf, NULL, 0);
    
52.     yc = simple_strtoul(p + 1, NULL, 0);
    
53.     
    
54.     if (!xc || !yc)
    
55.         goto out;
    
56. 
    
57.     vts_max_xc = xc;
    
58.     vts_max_yc = yc;
    
59.     return 1;
    
60. out:
    
61.     printk(KERN_WARNING "vts: option format must be like 'vts=widthxheigth'. "
    
62.             "use default config vts=%dx%d\n", vts_max_xc, vts_max_yc);
    
63.     return 0;
    
64. }
    
65. __setup("vts=", vts_setup);
    
66. #endif
    
67. 
    
68. static int __init vts_init(void)
    
69. {
    
70.     int err;
    
71. 
    
72. #ifndef MODULE
    
73.     if (!vts_use)
    
74.         return -ENODEV;
    
75. #endif
    
76.     vts_dev = input_allocate_device();
    
77.     if (!vts_dev) {
    
78.         printk(KERN_ERR "vts: not enough memory\n");
    
79.         err = -ENOMEM;
    
80.         goto fail1;
    
81.     }
    
82. 
    
83.     vts_dev->name = DRIVER_DESC;
    
84.     vts_dev->phys = "vts/input0";
    
85.     vts_dev->id.bustype = BUS_VIRTUAL;
    
86.     vts_dev->id.vendor = 0x0000;
    
87.     vts_dev->id.product = 0x0000;
    
88.     vts_dev->id.version = 0x0100;
    
89. 
    
90.     vts_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
    
91.     vts_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
    
92.     input_set_abs_params(vts_dev, ABS_X, VTS_MIN_XC, vts_max_xc, 0, 0);
    
93.     input_set_abs_params(vts_dev, ABS_Y, VTS_MIN_YC, vts_max_yc, 0, 0);
    
94. 
    
95.     err = input_register_device(vts_dev);
    
96.     if (err)
    
97.         goto fail2;
    
98. 
    
99.     return 0;
    
100. 
     
101. fail2:
     
102.     input_free_device(vts_dev);
     
103. fail1:
     
104.     return err;
     
105. }
     
106. module_init(vts_init);
     
107. #ifdef MODULE
     
108. static void __exit vts_exit(void)
     
109. {
     
110.     input_unregister_device(vts_dev);
     
111.     input_free_device(vts_dev);
     
112. }
     
113. module_exit(vts_exit);
     
114. #endif
     
115. MODULE_AUTHOR("Niu Tao ");
     
116. MODULE_DESCRIPTION(DRIVER_DESC);
     
117. MODULE_LICENSE("GPL");