【转载】帧缓冲驱动程序分析及其在BSP上的添加

原文地址：（四）帧缓冲驱动程序分析及其在BSP上的添加 作者：gfvvz

一、BSP修改及其分析

 

1. BSP中直接配置的四个寄存器

S3C6410数据手册的第14.5部分是显示控制器的编程模型部分，图1是开始部分截图。如第一行所说，这些寄存器是配置显示控制器用的。所以，所有的寄存器设置都围绕这些寄存器进行。

      其中前面四个寄存器SPCON、MOFPCON、VIDCON0与VIDCON0，直接在BSP中进行配置。

图 1

 

A. SPCON和MOFPCON寄存器：如下代码中，配置SPCON和MOFPCON寄存器，使得显示控制器工作于：“RGB I/F类型”、“normal模式”。

点击(此处)折叠或打开

1. /* 修改内容1：LCD接口类型及模式设置
2.  * BSP中位于 static void __init jason6410_map_io(void){} 函数内。
3.  */
4. /* set the LCD type */
5. tmp = __raw_readl(S3C64XX_SPCON);//读取当前SPCON寄存器值
6. tmp &= ~S3C64XX_SPCON_LCD_SEL_MASK;//清零LCD_SEL[1:0]
7. tmp |= S3C64XX_SPCON_LCD_SEL_RGB;//置位最后一位，LCD_SEL[1:0] = 01
8. __raw_writel(tmp, S3C64XX_SPCON);//写入LCD_SEL[1:0] = 01的值到SPCON寄存器，“RGB I/F style”
9. /* remove the lcd bypass */
10. tmp = __raw_readl(S3C64XX_MODEM_MIFPCON);//读取当前MOFPCON寄存器值
11. tmp &= ~MIFPCON_LCD_BYPASS;//清零SEL_BYPASS[3]
12. __raw_writel(tmp, S3C64XX_MODEM_MIFPCON);//写入SEL_BYPASS[3]已清零的值到MOFPCON寄存器，"normal mode"

点击(此处)折叠或打开

1. /* 使用到的宏定义 */ 
2. #define S3C64XX_SPCON_LCD_SEL_MASK      (0x3 << 0)
3. #define S3C64XX_SPCON_LCD_SEL_RGB       (0x1 << 0)
4. #define MIFPCON_LCD_BYPASS(1 << 3)

B、VIDCON0和VIDCON1寄存器：如下代码中，配置VIDCON0和VIDCON1寄存器。

a.配置VIDCON0寄存器: 输出格式为“RGB I/F”,显示模式为“RGB Parallel format (RGB)”;

b.配置VIDCON1寄存器：配置行同步信号HSYNC与帧同步信号VSYNC极性取反。因为S3C6410的LCD RGB接口的时序中，HSYNC和VSYNC与一般TFT屏极性相反，故需要配置极性取反。如下图5为S3C6410的LCD RGB接口的时序，下图6为一般TFT屏工作时序。

点击(此处)折叠或打开

1. /* 405566 clocks per frame => 60Hz refresh requires 24333960Hz clock */
2. static struct s3c_fb_platdata jason6410_lcd_pdata __initdata = {
3. .setup_gpio = s3c64xx_fb_gpio_setup_24bpp,//配置数据信号线GPIO
4. .win[0]     = &jason6410_fb_win0,//LCD屏参数
5. .vidcon0    = VIDCON0_VIDOUT_RGB | VIDCON0_PNRMODE_RGB,//配置VIDCON0寄存器
   
6.     .vidcon1    = VIDCON1_INV_HSYNC | VIDCON1_INV_VSYNC,//配置VIDCON1寄存器
7. };
8. //配置LCD数据信号线GPIO
9. extern void s3c64xx_fb_gpio_setup_24bpp(void)
10. {
11. s3c_gpio_cfgrange_nopull(S3C64XX_GPI(0), 16, S3C_GPIO_SFN(2));//GPI
12. s3c_gpio_cfgrange_nopull(S3C64XX_GPJ(0), 12, S3C_GPIO_SFN(2));//GPJ
13. }

点击(此处)折叠或打开

1. /* 使用到的宏定义 */ 
2. #define VIDCON0_VIDOUT_RGB            (0x0 << 26)  //见下图2
3. #define VIDCON0_PNRMODE_RGB(0x0 << 17)//见下图3
4. #define VIDCON1_INV_HSYNC(1 << 6)//见下图4
5. #define VIDCON1_INV_VSYNC(1 << 5)//见下图4

图 2

图 3

图4

图 5

图 6

 

2、帧缓冲设备参数计算及设置

 上面讲到的四个寄存器，对于同一处理器下不同厂家、不同尺寸的TFT屏基本上都是一样的。但是，对于下面几个定时和硬件参数：行切换、帧切换、水平同步长度、垂直同步长度、X像素、Y像素。不同厂家的不同尺寸的TFT屏之间，往往是不同的，或者说是需要重新计算和修改的。

下面先解释上面图5中的几个参数：

A. VBPD(vertical back porch)：表示在一帧图像开始时，垂直同步信号以后的无效的行数，对应驱动中的upper_margin；

B. VFBD(vertical front porch)：表示在一帧图像结束后，垂直同步信号以前的无效的行数，对应驱动中的lower_margin；

C. VSPW(vertical sync pulse width)：表示垂直同步脉冲的宽度，用行数计算，对应驱动中的vsync_len；

D. HBPD(horizontal back porch)：表示从水平同步信号开始到一行的有效数据开始之间的VCLK的个数，对应驱动中的left_margin；

E. HFPD(horizontal front porth)：表示一行的有效数据结束到下一个水平同步信号开始之间的VCLK的个数，对应驱动中的right_margin；

F. HSPW(horizontal sync pulse width)：表示水平同步信号的宽度，用VCLK计算，对应驱动中的hsync_len；

这几个参数都是基于行数或者VCLK个数，所以其数据必须是严格的，不能有偏差，一旦有一个数不对，整个屏幕都不能显示。

点击(此处)折叠或打开

1. static struct s3c_fb_pd_win jason6410_fb_win0 = {
2. /* this is to ensure we use win0 */
3. .win_mode    = {
4. #if 0
5. .pixclock    = 115440,//pixel clock in ps (pico seconds)
6. #endif
7. .left_margin    = 0x03,//time from sync to picture
8. .right_margin   = 0x02,//time from picture to sync
9. .upper_margin   = 0x01,//time from sync to picture
10. .lower_margin   = 0x01,//time from picture to sync
11. .hsync_len   = 0x28,//length of horizontal sync
12. .vsync_len    = 0x01,//length of vertical sync
13. .xres        = 480,
14. .yres        = 272,
15. },
16. .max_bpp    = 32,
17. .default_bpp    = 16,
18. };
19. 附：下图摘自内核里的Documentation/fb/framebuffer.txt
20. Video Mode Timings

 +----------+---------------------------------------------+----------+-------+
  |          |                ↑                            |          |       |
  |          |                |upper_margin                |          |       |
  |          |                ↓                            |          |       |
  +----------###############################################----------+-------+
  |          #                ↑                            #          |       |
  |          #                |                            #          |       |
  |          #                |                            #          |       |
  |          #                |                            #          |       |
  |   left   #                |                            #  right   | hsync |
  |  margin  #                |       xres                 #  margin  |  len  |
  |<-------->#<---------------+--------------------------->#<-------->|<----->|
  |          #                |                            #          |       |
  |          #                |                            #          |       |
  |          #                |                            #          |       |
  |          #                |yres                        #          |       |
  |          #                |                            #          |       |
  |          #                |                            #          |       |
  |          #                |                            #          |       |
  |          #                |                            #          |       |
  |          #                |                            #          |       |
  |          #                |                            #          |       |
  |          #                |                            #          |       |
  |          #                |                            #          |       |
  |          #                ↓                            #          |       |
  +----------###############################################----------+-------+
  |          |                ↑                            |          |       |
  |          |                |lower_margin                |          |       |
  |          |                ↓                            |          |       |
  +----------+---------------------------------------------+----------+-------+
  |          |                ↑                            |          |       |
  |          |                |vsync_len                   |          |       |
  |          |                ↓                            |          |       |
  +----------+---------------------------------------------+----------+-------+

3、BSP部分注册帧缓冲平台设备

如下代码完成s3c_device_fb平台设备结构体的设置。

点击(此处)折叠或打开

1. static struct s3c_fb_pd_win jason6410_fb_win0 = {
2. /* this is to ensure we use win0 */
3. .win_mode    = {
4. #if 0
5. .pixclock    = 115440,
6. #endif
7. .left_margin    = 0x03,
8. .right_margin   = 0x02,
9. .upper_margin   = 0x01,
10. .lower_margin   = 0x01,
11. .hsync_len    = 0x28,
12. .vsync_len    = 0x01,
13. .xres        = 480,
14. .yres        = 272,
15. },
16. .max_bpp    = 32,
17. .default_bpp    = 16,
18. };
19. /* 405566 clocks per frame => 60Hz refresh requires 24333960Hz clock */
20. static struct s3c_fb_platdata jason6410_lcd_pdata __initdata = {
21. .setup_gpio    = s3c64xx_fb_gpio_setup_24bpp,
22. .win[0]        = &jason6410_fb_win0,
23. .vidcon0    = VIDCON0_VIDOUT_RGB | VIDCON0_PNRMODE_RGB,
24. .vidcon1    = VIDCON1_INV_HSYNC | VIDCON1_INV_VSYNC,
25. };
26. //static void __init jason6410_machine_init(void)函数中：
27. s3c_fb_set_platdata(&jason6410_lcd_pdata);

参看arch/arm/plat-samsung/devs.c中FB部分，如下代码。

点击(此处)折叠或打开

1. /* FB */
2. #ifdef CONFIG_S3C_DEV_FB
3. static struct resource s3c_fb_resource[] = {
4. [0] = DEFINE_RES_MEM(S3C_PA_FB, SZ_16K),
5. [1] = DEFINE_RES_IRQ(IRQ_LCD_VSYNC),
6. [2] = DEFINE_RES_IRQ(IRQ_LCD_FIFO),
7. [3] = DEFINE_RES_IRQ(IRQ_LCD_SYSTEM),
8. };
9. struct platform_device s3c_device_fb = {
10. .name        = "s3c-fb",
11. .id        = -1,
12. .num_resources    = ARRAY_SIZE(s3c_fb_resource),
13. .resource    = s3c_fb_resource,
14. .dev        = {
15. .dma_mask        = &samsung_device_dma_mask,
16. .coherent_dma_mask    = DMA_BIT_MASK(32),
17. },
18. };
19. void __init s3c_fb_set_platdata(struct s3c_fb_platdata *pd)
20. {
21. s3c_set_platdata(pd, sizeof(struct s3c_fb_platdata),
22. &s3c_device_fb);
23. }
24. #endif /* CONFIG_S3C_DEV_FB */

最终，设置完s3c_device_fb平台设备结构体，结构体之间的关系如下：

点击(此处)折叠或打开

1. //1. s3c_device_fb平台设备结构体
2. struct platform_device s3c_device_fb = {
3. .name        = "s3c-fb",
4. .id        = -1,
5. .num_resources    = ARRAY_SIZE(s3c_fb_resource),
6. .resource    = s3c_fb_resource,
7. .dev        = {
8. .dma_mask        = &samsung_device_dma_mask,
9. .coherent_dma_mask    = DMA_BIT_MASK(32),
10. },
11. };
12. //2. s3c_device_fb平台设备结构体中的resource结构体
13. static struct resource s3c_fb_resource[] = {
14. [0] = DEFINE_RES_MEM(S3C_PA_FB, SZ_16K),
15. [1] = DEFINE_RES_IRQ(IRQ_LCD_VSYNC),
16. [2] = DEFINE_RES_IRQ(IRQ_LCD_FIFO),
17. [3] = DEFINE_RES_IRQ(IRQ_LCD_SYSTEM),
18. };
19. //3. s3c_device_fb平台设备结构体中的dev结构体里私有数据指针所指向的平台私有数据
20. static struct s3c_fb_platdata jason6410_lcd_pdata __initdata = {
21. .setup_gpio= s3c64xx_fb_gpio_setup_24bpp,
22. .win[0]= &jason6410_fb_win0,
23. .vidcon0= VIDCON0_VIDOUT_RGB | VIDCON0_PNRMODE_RGB,
24. .vidcon1= VIDCON1_INV_HSYNC | VIDCON1_INV_VSYNC,
25. };
26. //4. 平台私有数据jason6410_lcd_pdata结构体里的window_settings结构体
27. static struct s3c_fb_pd_win jason6410_fb_win0 = {
28. /* this is to ensure we use win0 */
29. .win_mode= {
30. #if 0
31. .pixclock= 115440,
32. #endif
33. .left_margin= 0x03,
34. .right_margin= 0x02,
35. .upper_margin= 0x01,
36. .lower_margin= 0x01,
37. .hsync_len= 0x28,
38. .vsync_len= 0x01,
39. .xres= 480,
40. .yres= 272,
41. },
42. .max_bpp= 32,
43. .default_bpp= 16,
44. };
45. /*
46. * 实际上，相当于有如下三个红色标注的结构体
47. * 1. 在jason6410_machine_init函数里的platform_add_devices函数注册s3c_device_fb平台设备结构体；
48. * 2. 通过私有数据指针找到jason6410_lcd_pdata结构体；
49. * 3. 通过s3c_fb_pd_win结构体指针，找到
    jason6410_fb_win0结构体；
50. */
51. struct platform_device s3c_device_fb = {
52. .name= "s3c-fb",
53. .id= -1,
54. .num_resources= ARRAY_SIZE(s3c_fb_resource),
55. .resource= {
56. [0] = DEFINE_RES_MEM(S3C_PA_FB, SZ_16K),
57. [1] = DEFINE_RES_IRQ(IRQ_LCD_VSYNC),
58. [2] = DEFINE_RES_IRQ(IRQ_LCD_FIFO),
59. [3] = DEFINE_RES_IRQ(IRQ_LCD_SYSTEM),
60. }
61. .dev= {
62. .platform_data= &jason6410_lcd_pdata,
63. .dma_mask= &samsung_device_dma_mask,
64. .coherent_dma_mask= DMA_BIT_MASK(32),
65. },
66. };
67. static struct s3c_fb_platdata jason6410_lcd_pdata __initdata = {
68. .setup_gpio= s3c64xx_fb_gpio_setup_24bpp,
69. .win[0]= &jason6410_fb_win0,
70. .vidcon0= VIDCON0_VIDOUT_RGB | VIDCON0_PNRMODE_RGB,
71. .vidcon1= VIDCON1_INV_HSYNC | VIDCON1_INV_VSYNC,
72. };
73. static struct s3c_fb_pd_win jason6410_fb_win0 = {
74. /* this is to ensure we use win0 */
75. .win_mode= {
76. #if 0
77. .pixclock= 115440,
78. #endif
79. .left_margin= 0x03,
80. .right_margin= 0x02,
81. .upper_margin= 0x01,
82. .lower_margin= 0x01,
83. .hsync_len= 0x28,
84. .vsync_len= 0x01,
85. .xres= 480,
86. .yres= 272,
87. },
88. .max_bpp= 32,
89. .default_bpp= 16,
90. };

 

点击(此处)折叠或打开

1. /* linux/arch/arm/mach-s3c64xx/mach-jason6410.c
2. *
3. * Copyright 2012 Jason Lu <gfvvz@yahoo.com.cn>
4. *     http://jason2012.blog.chinaunix.net
5. *
6. * This program is free software; you can redistribute it and/or modify
7. * it under the terms of the GNU General Public License version 2 as
8. * published by the Free Software Foundation.
9. *
10. */
11. #include <linux/init.h>
12. #include <linux/interrupt.h>
13. #include <linux/fb.h>
14. #include <linux/gpio.h>
15. #include <linux/kernel.h>
16. #include <linux/list.h>
17. #include <linux/dm9000.h>
18. #include <linux/mtd/mtd.h>
19. #include <linux/mtd/partitions.h>
20. #include <linux/serial_core.h>
21. #include <linux/types.h>
22. #include <asm/mach-types.h>
23. #include <asm/mach/arch.h>
24. #include <asm/mach/map.h>
25. #include <mach/map.h>
26. #include <mach/regs-gpio.h>
27. #include <mach/regs-modem.h>
28. #include <mach/regs-srom.h>
29. #include <plat/s3c6410.h>
30. #include <plat/adc.h>
31. #include <plat/cpu.h>
32. #include <plat/devs.h>
33. #include <plat/fb.h>
34. #include <plat/nand.h>
35. #include <plat/regs-serial.h>
36. #include <plat/ts.h>
37. #include <plat/regs-fb-v4.h>
38. #include <plat/iic.h>
39. #include <video/platform_lcd.h>
40. #define UCON S3C2410_UCON_DEFAULT
41. #define ULCON (S3C2410_LCON_CS8 | S3C2410_LCON_PNONE | S3C2410_LCON_STOPB)
42. #define UFCON (S3C2410_UFCON_RXTRIG8 | S3C2410_UFCON_FIFOMODE)
43. static struct s3c2410_uartcfg jason6410_uartcfgs[] __initdata = {
44. [0] = {
45. .hwport= 0,
46. .flags    = 0,
47. .ucon    = UCON,
48. .ulcon    = ULCON,
49. .ufcon    = UFCON,
50. },
51. [1] = {
52. .hwport    = 1,
53. .flags    = 0,
54. .ucon    = UCON,
55. .ulcon    = ULCON,
56. .ufcon    = UFCON,
57. },
58. [2] = {
59. .hwport    = 2,
60. .flags    = 0,
61. .ucon    = UCON,
62. .ulcon   = ULCON,
63. .ufcon    = UFCON,
64. },
65. [3] = {
66. .hwport    = 3,
67. .flags    = 0,
68. .ucon    = UCON,
69. .ulcon    = ULCON,
70. .ufcon    = UFCON,
71. },
72. };
73. /* Framebuffer. */
    
74.  
75. static struct s3c_fb_pd_win jason6410_fb_win0 = {
    
76.     /* this is to ensure we use win0 */
    
77.     .win_mode    = {
    
78. #if 0
    
79.         .pixclock    = 115440,
    
80. #endif
    
81.         .left_margin    = 0x03,
    
82.         .right_margin= 0x02,
    
83.         .upper_margin= 0x01,
    
84.         .lower_margin= 0x01,
    
85.         .hsync_len    = 0x28,
    
86.         .vsync_len   = 0x01,
    
87.         .xres        = 480,
    
88.         .yres        = 272,
    
89.     },
    
90.     .max_bpp    = 32,
    
91.     .default_bpp    = 16,
    
92. };
    
93.  
94. /* 405566 clocks per frame => 60Hz refresh requires 24333960Hz clock */
    
95. static struct s3c_fb_platdata jason6410_lcd_pdata __initdata = {
    
96.     .setup_gpio    = s3c64xx_fb_gpio_setup_24bpp,
    
97.     .win[0]        = &jason6410_fb_win0,
    
98.     .vidcon0    = VIDCON0_VIDOUT_RGB | VIDCON0_PNRMODE_RGB,
    
99.     .vidcon1    = VIDCON1_INV_HSYNC | VIDCON1_INV_VSYNC,
    
100. };
101. /* Nand flash */
102. static struct mtd_partition jason6410_nand_part[] = {
103. {
104. .name        = "u-boot-2011.06",
105. .offset        = 0,
106. .size        = (4 * 128 *SZ_1K),
107. .mask_flags    = MTD_CAP_NANDFLASH,
108. },
109. {
110. .name        = "Linux Kernel 3.2.8",
111. .offset        = MTDPART_OFS_APPEND,
112. .size        = (5*SZ_1M) ,
113. .mask_flags    = MTD_CAP_NANDFLASH,
114. },
115. {
116. .name        = "UBI File System",
117. .offset        = MTDPART_OFS_APPEND,
118. .size        = MTDPART_SIZ_FULL,
119. }
120. };
121. static struct s3c2410_nand_set jason6410_nand_sets[] = {
122. [0] = {
123. .name        = "nand",
124. .nr_chips    = 1,
125. .nr_partitions = ARRAY_SIZE(jason6410_nand_part),
126. .partitions    = jason6410_nand_part,
127. },
128. };
129. static struct s3c2410_platform_nand jason6410_nand_info = {
130. .tacls= 25,
131. .twrph0 = 55,
132. .twrph1  = 40,
133. .nr_sets    = ARRAY_SIZE(jason6410_nand_sets),
134. .sets     = jason6410_nand_sets,
135. };
136. static struct platform_device *jason6410_devices[] __initdata = {
137. &s3c_device_nand,
138. &s3c_device_i2c0,
139. &s3c_device_fb,
140. };
141. static struct i2c_board_info i2c_devs0[] __initdata = {
142. { I2C_BOARD_INFO("24c08", 0x50), },
143. };
144. static struct i2c_board_info i2c_devs1[] __initdata = {
145. /* Add your i2c device here */
146. };
147. static void __init jason6410_map_io(void)
148. {
149. u32 tmp;
150. s3c64xx_init_io(NULL, 0);
151. s3c24xx_init_clocks(12000000);
152. s3c24xx_init_uarts(jason6410_uartcfgs, ARRAY_SIZE(jason6410_uartcfgs));
153. /* set the LCD type */
     
154.     tmp = __raw_readl(S3C64XX_SPCON);
     
155.     tmp &= ~S3C64XX_SPCON_LCD_SEL_MASK;
     
156.     tmp |= S3C64XX_SPCON_LCD_SEL_RGB;
     
157.     __raw_writel(tmp, S3C64XX_SPCON);
     
158.  
159.     /* remove the lcd bypass */
     
160.     tmp = __raw_readl(S3C64XX_MODEM_MIFPCON);
     
161.     tmp &= ~MIFPCON_LCD_BYPASS;
     
162.     __raw_writel(tmp, S3C64XX_MODEM_MIFPCON);
163. }
164. static void __init jason6410_machine_init(void)
165. {
166. s3c_device_nand.name = "s3c6410-nand";
167. s3c_nand_set_platdata(&jason6410_nand_info);
168. s3c_i2c0_set_platdata(NULL);
169. s3c_fb_set_platdata(&jason6410_lcd_pdata);
170. if (ARRAY_SIZE(i2c_devs0)) {
171. i2c_register_board_info(0, i2c_devs0, ARRAY_SIZE(i2c_devs0));
172. }
173. if (ARRAY_SIZE(i2c_devs1)) {
174. i2c_register_board_info(1, i2c_devs1, ARRAY_SIZE(i2c_devs1));
175. }
176. platform_add_devices(jason6410_devices, ARRAY_SIZE(jason6410_devices));
177. }
178. MACHINE_START(JASON6410, "JASON6410")
179. /* Maintainer: Darius Augulis <augulis.darius@gmail.com> */
180. .atag_offset    = 0x100,
181. .init_irq= s3c6410_init_irq,
182. .map_io        = jason6410_map_io,
183. .init_machine    = jason6410_machine_init,
184. .timer        = &s3c24xx_timer,
185. MACHINE_END

4、帧缓冲平台驱动

 

4.1 s3c_fb_driver平台驱动结构体及其注册

平台设备与平台驱动匹配的函数如下，先尝试OF类型的匹配，如果匹配不成功，尝试驱动的id_table里是否有与设备名匹配的id，如果还是不能匹配，就回到基于驱动名和设备名的匹配。匹配成功返回1，失败返回0。

在这里，设备驱动结构体未定义of_match_table，故第一次匹配是不成功的。然后，平台驱动结构体里定义了id_table，且有与平台设备名相同的平台设备ID “s3c-fb”，因此在此匹配，并且把平台设备结构体的id_entry赋值为匹配的ID项。

点击(此处)折叠或打开

1. //平台设备设备与驱动匹配函数 
2. static int platform_match(struct device *dev, struct device_driver *drv)
3. {
4. struct platform_device *pdev = to_platform_device(dev);
5. struct platform_driver *pdrv = to_platform_driver(drv);
6. /* Attempt an OF style match first */
7. if (of_driver_match_device(dev, drv))
8. return 1;
9. /* Then try to match against the id table */
10. if (pdrv->id_table)
11. return platform_match_id(pdrv->id_table, pdev) != NULL;
12. /* fall-back to driver name match */
13. return (strcmp(pdev->name, drv->name) == 0);
14. }
15. //platform_match_id函数
16. static const struct platform_device_id *platform_match_id(
17. const struct platform_device_id *id,
18. struct platform_device *pdev)
19. {
20. while (id->name[0]) {
21. if (strcmp(pdev->name, id->name) == 0) {
22. pdev->id_entry = id;
23. return id;
24. }
25. id++;
26. }
27. return NULL;
28. }

点击(此处)折叠或打开

1. //@driver/video/s3c-fb.c 
2. //s3c_fb_driver平台驱动结构体
3. static struct platform_driver s3c_fb_driver = {
4. .probe       = s3c_fb_probe,
5. .remove      = __devexit_p(s3c_fb_remove),
6. .id_table    = s3c_fb_driver_ids,
7. .driver      = {
8. .name    = "s3c-fb",
9. .owner= THIS_MODULE,
10. .pm    = &s3cfb_pm_ops,
11. },
12. };
13. //s3c_fb_driver平台驱动结构体注册
14. static int __init s3c_fb_init(void)
15. {
16. return platform_driver_register(&s3c_fb_driver);
17. }
18. //s3c_fb_driver平台驱动结构体id_table
19. static struct platform_device_id s3c_fb_driver_ids[] = {
20. {
21. .name= "s3c-fb",//匹配平台设备名的名字
22. .driver_data= (unsigned long)&s3c_fb_data_64xx,
23. }, {
24. .name= "s5pc100-fb",
25. .driver_data= (unsigned long)&s3c_fb_data_s5pc100,
26. }, {
27. .name= "s5pv210-fb",
28. .driver_data= (unsigned long)&s3c_fb_data_s5pv210,
29. }, {
30. .name= "exynos4-fb",
31. .driver_data= (unsigned long)&s3c_fb_data_exynos4,
32. }, {
33. .name= "s3c2443-fb",
34. .driver_data= (unsigned long)&s3c_fb_data_s3c2443,
35. }, {
36. .name= "s5p64x0-fb",
37. .driver_data= (unsigned long)&s3c_fb_data_s5p64x0,
38. },
39. {},
40. };
41. //平台设备ID结构体中的驱动数据
42. static struct s3c_fb_driverdata s3c_fb_data_64xx = {
43. .variant = {
44. .nr_windows= 5,
45. .vidtcon= VIDTCON0,
46. .wincon= WINCON(0),
47. .winmap= WINxMAP(0),
48. .keycon= WKEYCON,
49. .osd= VIDOSD_BASE,
50. .osd_stride= 16,
51. .buf_start= VIDW_BUF_START(0),
52. .buf_size= VIDW_BUF_SIZE(0),
53. .buf_end= VIDW_BUF_END(0),
54. .palette = {
55. [0] = 0x400,
56. [1] = 0x800,
57. [2] = 0x300,
58. [3] = 0x320,
59. [4] = 0x340,
60. },
61. .has_prtcon= 1,
62. .has_clksel= 1,
63. },
64. .win[0]= &s3c_fb_data_64xx_wins[0],
65. .win[1]= &s3c_fb_data_64xx_wins[1],
66. .win[2]= &s3c_fb_data_64xx_wins[2],
67. .win[3]= &s3c_fb_data_64xx_wins[3],
68. .win[4]= &s3c_fb_data_64xx_wins[4],
69. };

4.2 s3c_fb_probe函数分析

点击(此处)折叠或打开

1. static int __devinit s3c_fb_probe(struct platform_device *pdev)
2. {
3. const struct platform_device_id *platid;
4. struct s3c_fb_driverdata *fbdrv;
5. struct device *dev = &pdev->dev;
6. struct s3c_fb_platdata *pd;
7. struct s3c_fb *sfb;
8. struct resource *res;
9. int win;
10. int ret = 0;
11. //platid指向平台设备结构体里的id_entry成员，即
    platid = pdev->id_entry；
12. platid = platform_get_device_id(pdev);
13. //fbdrv指向平台设备结构体id_entry项的driver_data成员
14. fbdrv = (struct s3c_fb_driverdata *)platid->driver_data;
15. //判断是否超出最大硬件支持的最大窗口数
16. if (fbdrv->variant.nr_windows > S3C_FB_MAX_WIN) {
17. dev_err(dev, "too many windows, cannot attach\n");
18. return -EINVAL;
19. }
20. //指向平台设备的平台数据
21. pd = pdev->dev.platform_data;
22. if (!pd) {
23. dev_err(dev, "no platform data specified\n");
24. return -EINVAL;
25. }
26. //1. 给s3c_fb结构体分配内存
27. sfb = kzalloc(sizeof(struct s3c_fb), GFP_KERNEL);
28. if (!sfb) {
29. dev_err(dev, "no memory for framebuffers\n");
30. return -ENOMEM;
31. }
32. dev_dbg(dev, "allocate new framebuffer %p\n", sfb);
33. //2. 设置s3c_fb结构体
34. sfb->dev = dev;   //指向设备
35. sfb->pdata = pd;   //指向平台设备的平台数据
36. sfb->variant = fbdrv->variant; //s3c_fb_variant结构体拷贝（结构体完全一样可直接拷贝）
37. spin_lock_init(&sfb->slock);   //初始化自旋锁
38. //3. 获取并使能模块总时钟
39. sfb->bus_clk = clk_get(dev, "lcd");//找到对应的bus clock，模块总时钟
40. if (IS_ERR(sfb->bus_clk)) {
41. dev_err(dev, "failed to get bus clock\n");
42. ret = PTR_ERR(sfb->bus_clk);
43. goto err_sfb;
44. }
45. clk_enable(sfb->bus_clk);//使能模块总时钟
46. if (!sfb->variant.has_clksel) {//判断driver_data里是否已定义源时钟
47. sfb->lcd_clk = clk_get(dev, "sclk_fimd");//未定义，用“sclk_fimd”去clock文件里找
48. if (IS_ERR(sfb->lcd_clk)) {
49. dev_err(dev, "failed to get lcd clock\n");
50. ret = PTR_ERR(sfb->lcd_clk);
51. goto err_bus_clk;
52. }
53. clk_enable(sfb->lcd_clk); //使能clock文件里找到的时钟源
54. }
55. pm_runtime_enable(sfb->dev); //使能设备运行时电源管理
56. //4. 获取平台设备数据 
57. //获取资源起始地址、结束地址，是显示控制器寄存器组地址
58. res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
59. if (!res) {
60. dev_err(dev, "failed to find registers\n");
61. ret = -ENOENT;
62. goto err_lcd_clk;
63. }
64. //为显示控制器寄存器组分配内存
65. sfb->regs_res = request_mem_region(res->start, resource_size(res),
66. dev_name(dev));
67. if (!sfb->regs_res) {
68. dev_err(dev, "failed to claim register region\n");
69. ret = -ENOENT;
70. goto err_lcd_clk;
71. }
72. //把寄存器组地址映射到内存
73.     //注:这里使用ioremap，所以，BSP中不需要编写针对LCD的I/O内存静态映射；
74. //   即static struct map_desc jason6410_iodesc[]{}；里面这部分。
75. sfb->regs = ioremap(res->start, resource_size(res));
76. if (!sfb->regs) {
77. dev_err(dev, "failed to map registers\n");
78. ret = -ENXIO;
79. goto err_req_region;
80. }
81. //获取资源中的中断部分
82. res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
83. if (!res) {
84. dev_err(dev, "failed to acquire irq resource\n");
85. ret = -ENOENT;
86. goto err_ioremap;
87. }
88. sfb->irq_no = res->start;
89. ret = request_irq(sfb->irq_no, s3c_fb_irq,//注册中断处理函数
90. 0, "s3c_fb", sfb);
91. if (ret) {
92. dev_err(dev, "irq request failed\n");
93. goto err_ioremap;
94. }
95. dev_dbg(dev, "got resources (regs %p), probing windows\n", sfb->regs);
96. //pdev->dev->p->driver_data = sfb
97. platform_set_drvdata(pdev, sfb);
98. //运行时恢复操作的入口
99. pm_runtime_get_sync(sfb->dev);
100. /* setup gpio and output polarity controls */
101. //5. 设置寄存器组
102. pd->setup_gpio(); //设置数据线的GPIO，pd见23行，即s3c64xx_fb_gpio_setup_24bpp，见BSP
103. writel(pd->vidcon1, sfb->regs + VIDCON1); //写VIDCON1寄存器
104. /* zero all windows before we do anything */
105. for (win = 0; win < fbdrv->variant.nr_windows; win++) //复位所有窗口寄存器
106. s3c_fb_clear_win(sfb, win);
107. /* initialise colour key controls */ //初始化
108. for (win = 0; win < (fbdrv->variant.nr_windows - 1); win++) {
109. void __iomem *regs = sfb->regs + sfb->variant.keycon;
110. regs += (win * 8);//GNU下空指针可以算数运算，并且算法操作与char *一致
111. writel(0xffffff, regs + WKEYCON0); //详见S3C6410X.pdf 516页
112. writel(0xffffff, regs + WKEYCON1);
113. }
114. /* we have the register setup, start allocating framebuffers */
115. //6. 设置完寄存器，开始分配帧缓冲
116. for (win = 0; win < fbdrv->variant.nr_windows; win++) {
117. if (!pd->win[win])
118. continue;
119. if (!pd->win[win]->win_mode.pixclock) //如果未定义像素时钟，在此计算
120. s3c_fb_missing_pixclock(&pd->win[win]->win_mode); //计算像素时钟
121. //注册硬件窗口,下面展开细说
122. ret = s3c_fb_probe_win(sfb, win, fbdrv->win[win],
123. &sfb->windows[win]);
124. if (ret < 0) {
125. dev_err(dev, "failed to create window %d\n", win);
126. for (; win >= 0; win--)
127. s3c_fb_release_win(sfb, sfb->windows[win]);
128. goto err_irq;
129. }
130. }
131. //再一次，同line 112/114
132. platform_set_drvdata(pdev, sfb);
133. pm_runtime_put_sync(sfb->dev);
134. return 0;
135. err_irq:
136. free_irq(sfb->irq_no, sfb);
137. err_ioremap:
138. iounmap(sfb->regs);
139. err_req_region:
140. release_mem_region(sfb->regs_res->start, resource_size(sfb->regs_res));
141. err_lcd_clk:
142. if (!sfb->variant.has_clksel) {
143. clk_disable(sfb->lcd_clk);
144. clk_put(sfb->lcd_clk);
145. }
146. err_bus_clk:
147. clk_disable(sfb->bus_clk);
148. clk_put(sfb->bus_clk);
149. err_sfb:
150. kfree(sfb);
151. return ret;
152. }

4.3 s3c_fb_probe_win函数分析(注册硬件窗口)

点击(此处)折叠或打开

1. /**
2. * s3c_fb_probe_win() - register an hardware window
3. * @sfb: The base resources for the hardware
4. * @variant: The variant information for this window.
5. * @res: Pointer to where to place the resultant window.
6. *
7. * Allocate and do the basic initialisation for one of the hardware's graphics
8. * windows.
9. */
10. static int __devinit s3c_fb_probe_win(struct s3c_fb *sfb, unsigned int win_no,
11. struct s3c_fb_win_variant *variant,
12. struct s3c_fb_win **res)
13. {
14. struct fb_var_screeninfo *var;
15. struct fb_videomode *initmode;
16. struct s3c_fb_pd_win *windata;
17. struct s3c_fb_win *win;
18. struct fb_info *fbinfo;
19. int palette_size;
20. int ret;
21. dev_dbg(sfb->dev, "probing window %d, variant %p\n", win_no, variant);
22. init_waitqueue_head(&sfb->vsync_info.wait);    //初始化等待队列头
23. palette_size = variant->palette_sz * 4;    //设置调色板大小
24. //1.创建fb_info结构体，并分配驱动私有数据
25. fbinfo = framebuffer_alloc(sizeof(struct s3c_fb_win) +
26. palette_size * sizeof(u32), sfb->dev);
27. if (!fbinfo) {
28. dev_err(sfb->dev, "failed to allocate framebuffer\n");
29. return -ENOENT;
30. }
31. //windata指向平台设备驱动私有数据里的win[win_no]成员，这里是BSP中的jason6410_fb_win0结构体
32. //initmode指向jason6410_fb_win结构体里的win_mode成员

33. 点击(此处)折叠或打开

    1. static struct s3c_fb_pd_win jason6410_fb_win0 = {
    2. /* this is to ensure we use win0 */
    3. .win_mode    = {
    4. #if 0
    5. .pixclock    = 115440,
    6. #endif
    7. .left_margin    = 0x03,
    8. .right_margin    = 0x02,
    9. .upper_margin    = 0x01,
    10. .lower_margin    = 0x01,
    11. .hsync_len    = 0x28,
    12. .vsync_len    = 0x01,
    13. .xres        = 480,
    14. .yres        = 272,
    15. },
    16. .max_bpp    = 32,
    17. .default_bpp    = 16,
    18. };
34. windata = sfb->pdata->win[win_no];
35. initmode = &windata->win_mode;
36. WARN_ON(windata->max_bpp == 0);//调用dump_stack，打印堆栈信息
37. WARN_ON(windata->win_mode.xres == 0);
38. WARN_ON(windata->win_mode.yres == 0);
39. //2. 帧缓冲每个窗口的s3c_fb_win结构体设置
40. win = fbinfo->par; //见代码30行分配fb_info结构体部分，在那fbinfo->par已指向驱动私有数据
41. *res = win;//*res指向win
42. var = &fbinfo->var; //var指向fb_var_screeninfo结构体
43. win->variant = *variant;//结构体复制（同一类型结构体可以复制）
44. win->fbinfo = fbinfo;//fbinfo指向fb_info结构体
45. win->parent = sfb;//parent指向s3c_fb结构体
46. win->windata = windata;     //windata指向s3c_fb_pd_win结构体
47. win->index = win_no;//编号
48. win->palette_buffer = (u32 *)(win + 1); //指向调色板缓冲区
49. //3. 为帧缓冲的窗口分配显示内存
50. ret = s3c_fb_alloc_memory(sfb, win);
51. if (ret) {
52. dev_err(sfb->dev, "failed to allocate display memory\n");
53. return ret;
54. }
55. /* setup the r/b/g positions for the window's palette */
56. //4. 为窗口调色板设置r/g/b的位置,这里的palette_16bpp为初始化值1,程序中未对其赋值

57. 点击(此处)折叠或打开

    1. //该结构体位于4.1节
    2. struct s3c_fb_win_variant {
    3. unsigned int    has_osd_c:1;
    4. unsigned int    has_osd_d:1;
    5. unsigned int    has_osd_alpha:1;
    6. unsigned int    palette_16bpp:;
    7. unsigned short    osd_size_off;
    8. unsigned short    palette_sz;
    9. u32        valid_bpp;
    10. };
58. if (win->variant.palette_16bpp) {
59. /* Set RGB 5:6:5 as default */
60. win->palette.r.offset = 11;
61. win->palette.r.length = 5;
62. win->palette.g.offset = 5;
63. win->palette.g.length = 6;
64. win->palette.b.offset = 0;
65. win->palette.b.length = 5;
66. } else {
67. /* Set 8bpp or 8bpp and 1bit alpha */
68. win->palette.r.offset = 16;
69. win->palette.r.length = 8;
70. win->palette.g.offset = 8;
71. win->palette.g.length = 8;
72. win->palette.b.offset = 0;
73. win->palette.b.length = 8;
74. }
75. /* setup the initial video mode from the window */
76. //5. 设置初始视频模式，填充结构体fbinfo
77. //将fb_videomode结构体中成员赋值给fb_var_screeninfo结构体对应成员
78. fb_videomode_to_var(&fbinfo->var, initmode);
79. fbinfo->fix.type    = FB_TYPE_PACKED_PIXELS;
80. fbinfo->fix.accel    = FB_ACCEL_NONE;
81. fbinfo->var.activate    = FB_ACTIVATE_NOW;
82. fbinfo->var.vmode    = FB_VMODE_NONINTERLACED;
83. fbinfo->var.bits_per_pixel = windata->default_bpp;
84. fbinfo->fbops        = &s3c_fb_ops;
85. fbinfo->flags        = FBINFO_FLAG_DEFAULT;
86. fbinfo->pseudo_palette = &win->pseudo_palette;
87. /* prepare to actually start the framebuffer */
88. //6. 检查可变参数，帧缓冲层核实信息，并根据硬件能力更新几种信息。
89. ret = s3c_fb_check_var(&fbinfo->var, fbinfo);
90. if (ret < 0) {
91. dev_err(sfb->dev, "check_var failed on initial video params\n");
92. return ret;
93. }
94. /* create initial colour map */
95. //7. 分配和设置fb_cmap结构体，该结构体记录设备无关的颜色表信息
96. ret = fb_alloc_cmap(&fbinfo->cmap, win->variant.palette_sz, 1);
97. if (ret == 0)
98. fb_set_cmap(&fbinfo->cmap, fbinfo);
99. else
100. dev_err(sfb->dev, "failed to allocate fb cmap\n");
101. //8. 设置帧缓冲模式
102. s3c_fb_set_par(fbinfo);
103. dev_dbg(sfb->dev, "about to register framebuffer\n");
104. /* run the check_var and set_par on our configuration. */
105. //9. 注册一个帧缓冲设备
106. ret = register_framebuffer(fbinfo);
107. if (ret < 0) {
108. dev_err(sfb->dev, "failed to register framebuffer\n");
109. return ret;
110. }
111. dev_info(sfb->dev, "window %d: fb %s\n", win_no, fbinfo->fix.id);
112. return 0;
113. }

 

5、帧缓冲设备的用户空间访问

运行如下代码，在LCD显示屏上绘制R/G/B这三种颜色的由浅入深的变化情况。

点击(此处)折叠或打开

1. /*
2. * S3C6410 framebuffer test programs
3. */
4. #include <unistd.h>
5. #include <stdlib.h>
6. #include <stdio.h>
7. #include <fcntl.h>
8. #include <linux/fb.h>
9. #include <sys/mman.h>
10. int main()
11. {
12. int fbfd = 0;
13. struct fb_var_screeninfo vinfo;
14. unsigned long screensize = 0;
15. char *fbp = 0;
16. int x = 0, y = 0;
17. int i = 0;
18. // Open the file for reading and writing
19. fbfd = open("/dev/fb0", O_RDWR);
20. if (!fbfd) {
21. printf("Error: cannot open framebuffer device.\n");
22. exit(1);
23. }
24. printf("The framebuffer device was opened successfully.\n");
25. // Get variable screen information
26. if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo)) {
27. printf("Error reading variable information.\n");
28. exit(1);
29. }
30. printf("%dx%d, %dbpp\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel);
31. if (vinfo.bits_per_pixel != 16) {
32. printf("Error: not supported bits_per_pixel, it only supports 16 bit color\n");
33. exit(1);
34. }
35. // Figure out the size of the screen in bytes
36. screensize = vinfo.xres * vinfo.yres * 2;
37. // Map the device to memory
38. fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED,
39. fbfd, 0);
40. if ((int)fbp == -1) {
41. printf("Error: failed to map framebuffer device to memory.\n");
42. exit(4);
43. }
44. printf("The framebuffer device was mapped to memory successfully.\n");
45. // Draw 3 rect with graduated RED/GREEN/BLUE
46. for (i = 0; i < 3; i++) {
47. for (y = i * (vinfo.yres / 3); y < (i + 1) * (vinfo.yres / 3); y++) {
48. for (x = 0; x < vinfo.xres; x++) {
49. long location = x * 2 + y * vinfo.xres * 2;
50. int r = 0, g = 0, b = 0;
51. unsigned short rgb;
52. if (i == 0)
53. r = ((x * 1.0) / vinfo.xres) * 32;
54. if (i == 1)
55. g = ((x * 1.0) / vinfo.xres) * 64;
56. if (i == 2)
57. b = ((x * 1.0) / vinfo.xres) * 32;
58. rgb = (r << 11) | (g << 5) | b;
59. *((unsigned short*)(fbp + location)) = rgb;
60. }
61. }
62. }
63. munmap(fbp, screensize);
64. close(fbfd);
65. return 0;
66. }

测试方法（LCD尺寸有所不同，仅作参考）：

 

 

 

 

 

二、内核修改

下列代码是I/O静态内存映射，s3c-fb.c里通过ioremap映射需配置的寄存器，所以无需做静态内存映射，所以内核部分可不做任何修改（不包括BSP）。如果驱动里用的是虚拟地址，则必须使用下列代码。

点击(此处)折叠或打开

1. gedit arch/arm/plat-samsung/include/plat/map-base.h
2. line 39 add:
3. #define S3C_VA_LCD    S3C_ADDR(0x01100000) /* LCD */

在BSP中添加：

点击(此处)折叠或打开

1. static struct map_desc jason6410_iodesc[] = {
2. {
3. /* LCD support */
4. .virtual = (unsigned long)S3C_VA_LCD,//虚拟地址
5. .pfn = __phys_to_pfn(S3C_PA_FB),//物理地址
6. .length = SZ_16K,
7. .type = MT_DEVICE,
8. },
9. };
10. static void __init jason6410_map_io(void)
11. {
12. s3c64xx_init_io(jason6410_iodesc, ARRAY_SIZE(jason6410_iodesc)); //初始化
13. ......
14. }

 

三、内核配置

 

点击(此处)折叠或打开

1. Device Drivers --->
2. Graphics support --->
3. <*> Support for frame buffer devices --->
4. <*> Samsung S3C framebuffer support
5. Device Drivers --->
6. Graphics support --->
7. [ ] Backlight & LCD device support --->
8. Device Drivers --->
9. Graphics support --->
10. Console display driver support --->
11. <*> Framebuffer Console support
12. Device Drivers --->
13. Graphics support --->
14. [*] Bootup logo --->

四、启动Logo修改

1. 找到自己喜欢的图片，用Photoshop裁剪为屏幕尺寸大小，这里是480*272;

2. PS软件里选 文件 ---> 存储为，在弹出框里输入保存名，保存类型选BMP格式；按确定后会弹出如下窗口，如红色方框内选择，选择深度为24位。产生logo.bmp(480*272,24bpp)，在此 logo.zip  

3. 重复步骤2中前面步骤，在最后的弹出框点选高级模式，并选如下图所示，产生logo_cat.bmp(480*272,16bpp,R/G/B:5/6/5),该图用于"cat logo_cat.bmp > /dev/fb0"演示。 logo_cat.zip  

 

4. 接下来的步骤在Linux下进行，将步骤2生成的logo.bmp并不能用在内核中，需做进一步修改，先把它拷贝到虚拟机里某一目录下，执行如下转换。

点击(此处)折叠或打开

1. # bmptoppm logo.bmp > logo.ppm
2. # ppmquant 224 logo.ppm > logo_224.ppm
3. # pnmnoraw logo_224.ppm > logo_linux_clut224.ppm

5. 将上一步骤中生成的logo_linux_clut224.ppm拷贝到内核目录：drivers/video/logo/覆盖原有图片。

6. 如果已经编译过内核，直接再次编译，图片很有可能是原来的或者是没显示，可以执行如下命令清楚中间结果，而不必用make distclean清空，实在不行再用此命令，有时会有的，不知为何，呵呵。

点击(此处)折叠或打开

1. # rm drivers/video/logo/.l*

7. 执行如下命令，烧写内核，就能看到启动界面。

点击(此处)折叠或打开

1. make uImage -j4

 8. 内核挂上文件系统后，传入步骤3中产生的logo_cat.bmp，执行如下命令，能看到图片。现在还有点问题，图片倒过来的，并且水平有偏移。

点击(此处)折叠或打开

1. cat logo_cat.bmp > /dev/fb0

注意：在内核里必须勾选如下选项，不选择，是显示不了启动图片的。

点击(此处)折叠或打开

1. Device Drivers --->
2. Graphics support --->
3. Console display driver support --->
4. <*> Framebuffer Console support

附录1：启动界面

 

 

附录2：cat logo_cat.bmp > /dev/fb0 后屏幕显示

 

 

五、启动QT

 现在做的主要是内核移植，文件系统用的还是友善自带的，但是如上修改后，界面程序还是启动不了，且无人任何错误信息。文件系统里是有保证界面启动的库函数的，所以问题应该出现在驱动或者内核配置上。

友
善自带的文件系统里有三个界面程序，我试着打开qt4（“/bin/qt4 &”
命令）那个界面时，有错误提示了，先是socket相关错误，就照着友善2.6.38内核的配置，配置了Networking
support下的内核选项。接着报信号量错误，就照着友善的配置在Gernel Setup下配置内核选项。现在能启动界面了。

还
有一个问题是，友善文件系统里自带的rcS有输出信息输出到显示屏上，不好看。就在文件系统里的etc/init.d/rcS里，把所有 ">
/dev/tty1"都注释掉，这样这些打印信息只会在串口终端里显示，不会影响界面显示了。用如下命令生成新的ubi文件系统。

点击(此处)折叠或打开

1. # mkubimage-slc  rootfs_qtopia_qt4  rootfs_qtopia_qt4-slc.ubi

 step2.3_my_BSP_jason6410_lcd.zip