Linux-2.6.39在Tiny6410上的移植 - 外设驱动移植
Linux内核版本号：linux 2.6.39
交叉编译工具：arm-linux-gcc 4.5.1
Linux内核下载：www.kernel.org
开发板：友善之臂Tiny6410
LCD：友善之臂S70
一、移植LED驱动
打开arch/arm/mach-s3c64xx/mach-mini6410.c添加下列代码：
1 static struct gpio_led tiny6410_gpio_led[] = {
2 [0] = {
3 .name = "led1", //设备名
4 .gpio = S3C64XX_GPK(4), //GPK4
5 .active_low = 1, //低电平点亮
6 .default_state = LEDS_GPIO_DEFSTATE_ON, //系统启动后默认为打开
7 },
8 [1] = {
9 .name = "led2",
10 .gpio = S3C64XX_GPK(5),
11 .active_low = 1,
12 .default_state = LEDS_GPIO_DEFSTATE_OFF, //系统启动后默认关闭
13 },
14 [2] = {
15 .name = "led3",
16 .gpio = S3C64XX_GPK(6),
17 .active_low = 1,
18 .default_state = LEDS_GPIO_DEFSTATE_ON,
19 },
20 [3] = {
21 .name = "led4",
22 .gpio = S3C64XX_GPK(7),
23 .active_low = 1,
24 .default_state = LEDS_GPIO_DEFSTATE_OFF,
25 },
26 };
27
28 static struct gpio_led_platform_data tiny6410_leds_data = {
29 .num_leds = ARRAY_SIZE(tiny6410_gpio_led),
30 .leds = &tiny6410_gpio_led,
31 };
32
33 static struct platform_device tiny6410_device_leds = {
34 .name = "leds-gpio",
35 .id = -1,
36 .dev = {
37 .platform_data = &tiny6410_leds_data,
38 },
39 };
在mini6410_devices中添加tiny6410_device_leds，系统启动时将自动注册LED平台设备：
1 static struct platform_device *mini6410_devices[] __initdata = {
2 ...
3 &tiny6410_device_leds,
4 };
执行make menuconfig修改内核配置，添加对LED设备的支持：
Device Drivers --->
│ │ [*] LED Support --->
│ │ [*] LED Class Support
│ │ *** LED drivers ***
│ │ <*> LED Support for GPIO connected LEDs
│ │ [*] Platform device bindings for GPIO LEDs
编译并烧写内核，启动开发板可以看到第一、第三个LED被点亮。
编写应用程序控制LED：
系统LED设备名为每个LED设备创建了一个节点文件夹，位于/sys/devices/platform/leds-gpio/leds/目录下，对设备文件夹里面的brightness 文件写0或写非0即可对LED进行操作。
1 #include <stdio.h>
2 #include <sys/stat.h>
3 #include <sys/types.h>
4 #include <fcntl.h>
5 #include <stdlib.h>
6 #include <string.h>
7
8
9 int main(int argc,char** argv)
10 {
11 int fd = 0;
12 char path[64] = "/sys/devices/platform/leds-gpio/leds/";
13
14 if(argc != 3)
15 {
16 printf("format error!\n");
17 return -1;
18 }
19
20 strcat(path,argv[1]);
21 strcat(path,"/brightness");
22
23 printf("%s\n",path);
24 fd = open(path,O_RDWR);
25 if(fd == -1)
26 {
27 printf("open file failure!\n");
28 return -1;
29 }
30 if(atoi(argv[2]))
31 write(fd,"1",1);
32 else
33 write(fd,"0",1);
34
35 close(fd);
36 return 0;
37 }
二、按键驱动移植
在arch/arm/mach-s3c64xx/mach-mini6410.c添加下列代码：
1 static struct gpio_keys_button tiny6410_gpio_keys[] = {
2 [0] = {
3 .code = KEY_F1, //键值
4 .type = EV_KEY, //按键输入类型
5 .gpio = S3C64XX_GPN(0),
6 .active_low = 1, //低电平表示按下
7 .wakeup = 0,
8 .debounce_interval = 5, /* ms */ //延时消抖
9 .desc = "Button 1",
10 },
11 [1] = {
12 .code = KEY_F2,
13 .type = EV_KEY,
14 .gpio = S3C64XX_GPN(1),
15 .active_low = 1,
16 .wakeup = 0,
17 .debounce_interval = 5, /* ms */
18 .desc = "Button 2",
19 },
20 [2] = {
21 .code = KEY_F3,
22 .type = EV_KEY,
23 .gpio = S3C64XX_GPN(2),
24 .active_low = 1,
25 .wakeup = 0,
26 .debounce_interval = 5, /* ms */
27 .desc = "Button 3",
28 },
29 [3] = {
30 .code = KEY_F4,
31 .type = EV_KEY,
32 .gpio = S3C64XX_GPN(3),
33 .active_low = 1,
34 .wakeup = 0,
35 .debounce_interval = 5, /* ms */
36 .desc = "Button 4",
37 },
38
39 };
40
41 static struct gpio_keys_platform_data tiny6410_key_data = {
42 .buttons = &tiny6410_gpio_keys,
43 .nbuttons = ARRAY_SIZE(tiny6410_gpio_keys),
44 };
45
46 static struct platform_device tiny6410_device_keys = {
47 .name = "gpio-keys",
48 .id = -1,
49 .dev = {
50 .platform_data = &tiny6410_key_data,
51 },
52 };
在mini6410_devices中添加tiny6410_device_keys:
1 static struct platform_device *mini6410_devices[] __initdata = {
2 ....
3 &tiny6410_device_leds,
4 &tiny6410_device_keys,
5 };
执行make menuconfig修改内核配置，添加对LED设备的支持：
Device Drivers --->
│ │ Input device support --->
│ │ [*] Keyboards --->
│ │ <*> GPIO Buttons
同时在Input device support里面添加event interface的支持，在/dev/下面就能生成一个event设备文件：
Device Drivers --->
│ │ Input device support --->
│ │ <*> Event interface
编译并烧写内核，启动开发板可以在/dev/目录下生成了event0设备文件，对按键驱动进行简单的测试：
执行hexdump /dev/event0
每次按下按键可以看到如下所示按键信息，表明按键是工作正常的。
1 /dev # hexdump event0 2 0000000 034d 0000 0e3b 000c 0001 003b 0001 0000 3 0000010 034d 0000 0e4c 000c 0000 0000 0000 0000 4 0000020 034d 0000 cd5f 000e 0001 003b 0000 0000 5 0000030 034d 0000 cd6b 000e 0000 0000 0000 0000
编写应用程序测试按键驱动：
按键驱动为输入子系统，应用程序中需要对event进行循环检测看系统有没有上报输入事件，按键的输入事件类型为EV_KEY，键值分别问KEY_F1、KEY_F2、KEY_F3、KEY_F4，数值为1表示按键按下为0表示按键释放。
1 #include <stdio.h>
2 #include <sys/stat.h>
3 #include <sys/types.h>
4 #include <fcntl.h>
5 #include <stdlib.h>
6 #include <linux/input.h>
7
8 int main(void)
9 {
10 int fd = 0;
11 struct input_event event_key;
12 int count = 0;
13
14 fd = open("/dev/event0",O_RDONLY);
15 if(fd == -1)
16 {
17 printf("open file failed\n");
18 return -1;
19 }
20
21 while(1)
22 {
23 count = read(fd,&event_key,sizeof(struct input_event));
24 if(count < 0)
25 {
26 printf("read failed\n");
27 break;
28 }
29 if(event_key.type == EV_KEY)
30 {
31 switch(event_key.code)
32 {
33 case KEY_F1:
34 {
35 if(event_key.value == 1)
36 printf("key1 pressed\n");
37 else if(event_key.value == 0)
38 printf("key1 released\n");
39 }
40 break;
41 case KEY_F2:
42 {
43 if(event_key.value == 1)
44 printf("key2 pressed\n");
45 else if(event_key.value == 0)
46 printf("key2 released\n");
47 }
48 break;
49 case KEY_F3:
50 {
51 if(event_key.value == 1)
52 printf("key3 pressed\n");
53 else if(event_key.value == 0)
54 printf("key3 released\n");
55 }
56 break;
57 case KEY_F4:
58 {
59 if(event_key.value == 1)
60 printf("key4 pressed\n");
61 else if(event_key.value == 0)
62 printf("key4 released\n");
63 }
64 break;
65 }
66 }
67
68 }
69
70 close(fd);
71 return 0;
72 }
三、LCD显示屏移植
在arch/arm/mach-s3c64xx/mach-mini6410.c修改显示代码：
1 static struct s3c_fb_pd_win mini6410_fb_win[] = {
2 {
3 .win_mode = { /* 7.0" 800x480 */
4 .left_margin = 0x2c,//26,
5 .right_margin = 0xd2,//210,
6 .upper_margin = 0x15,//13,
7 .lower_margin = 0x16,//22,
8 .hsync_len = 0x02,//20,
9 .vsync_len = 0x02,//10,
10 .xres = 800,
11 .yres = 480,
12 },
13 .max_bpp = 32,
14 .default_bpp = 16,
15 },
16 };
参数的值根据LCD显示屏规格书确定，具体参数解释及计算见博客http://blog.csdn.net/longxiaowu/article/details/24319933
执行make menuconfig修改内核配置，添加对LCD设备的支持：
Device Drivers --->
│ │ Input device support --->
│ │ Graphics support --->
│ │ <*> Support for frame buffer devices --->
│ │ <*> Samsung S3C framebuffer support
│ │ [*] Bootup logo ---> //开机显示小企鹅
│ │ --- Bootup logo │ │
│ │ [ ] Standard black and white Linux logo
│ │ [ ] Standard 16-color Linux logo
│ │ [*] Standard 224-color Linux logo
编译烧写内核并开机，屏幕上并没有看到小企鹅。加载Tiny6410一线触摸设备驱动之后小企鹅出来了，应该是Tiny6410 S70屏幕的背光是在一线触摸中进行打开的，由于一线触摸的协议并不开源所以没有进行深究。