LCD驱动分析(三)： framebuffer驱动的注册

原文地址：LCD驱动分析(三)： framebuffer驱动的注册 作者：huabinbin00

这里最好牵涉到几个文件 S3cfb.c、S3cfb_fimd6x.c setuo-fb.c fb_mem.c

在这里之前最好知道pci，和memio一些术语的意思

S3cfb.c中的s3cfb_probe设备探测，是驱动注册的主要函数

 

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1. /*定义一个结构体用来维护驱动程序中各函数中用到的变量
   
2.   先别看结构体要定义这些成员，到各函数使用的地方就明白了*/
   
3. static int __devinit s3cfb_probe(struct platform_device *pdev)
   
4. {
   
5.     struct s3c_platform_fb *pdata;/*LCD屏配置信息结构体*/
   
6.     struct s3cfb_global *fbdev;/*驱动程序全局变量结构体*/
   
7.     struct resource *res; /*用来保存从LCD平台设备中获取的LCD资源*/
   
8.     int i, j, ret = 0;
   
9. 
   
10.     printk("%s\n",__func__);
    
11.     fbdev = kzalloc(sizeof(struct s3cfb_global), GFP_KERNEL);
    
12.     if (!fbdev) {
    
13.         dev_err(&pdev->dev, "failed to allocate for "
    
14.             "global fb structure\n");
    
15.         ret = -ENOMEM;
    
16.         goto err_global;
    
17.     }
    
18.     fbdev->dev = &pdev->dev;
    
19. 
    
20.     fbdev->regulator = regulator_get(&pdev->dev, "pd");
    
21.     if (!fbdev->regulator) {
    
22.         dev_err(fbdev->dev, "failed to get regulator\n");
    
23.         ret = -EINVAL;
    
24.         goto err_regulator;
    
25.     }
    
26.     ret = regulator_enable(fbdev->regulator);
    
27.     if (ret < 0) {
    
28.         dev_err(fbdev->dev, "failed to enable regulator\n");
    
29.         ret = -EINVAL;
    
30.         goto err_regulator;
    
31.     }
    
32. 
    
33.     /*获取LCD参数信息*/
    
34.     pdata = to_fb_plat(&pdev->dev);
    
35.     if (!pdata) {
    
36.         dev_err(fbdev->dev, "failed to get platform data\n");
    
37.         ret = -EINVAL;
    
38.         goto err_pdata;
    
39.     }
    
40. 
    
41.     fbdev->lcd = (struct s3cfb_lcd *)pdata->lcd;
    
42. 
    
43.     /*配置GPIO端口*/
    
44.     if (pdata->cfg_gpio)
    
45.         pdata->cfg_gpio(pdev);
    
46. 
    
47.     /*设置时钟参数*/
    
48.     if (pdata->clk_on)
    
49.         pdata->clk_on(pdev, &fbdev->clock);
    
50. 
    
51.     /*获取LCD平台设备所使用的IO端口资源，注意这个IORESOURCE_MEM标志和LCD平台设备定义中的一致*/
    
52.     res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    
53.     if (!res) {
    
54.         dev_err(fbdev->dev, "failed to get io memory region\n");
    
55.         ret = -EINVAL;
    
56.         goto err_io;
    
57.     }
    
58. 
    
59.     /*申请LCD IO端口所占用的IO空间(注意理解IO空间和内存空间的区别),request_mem_region定义在ioport.h中*/
    
60.     res = request_mem_region(res->start,
    
61.                  res->end - res->start + 1, pdev->name);
    
62.     if (!res) {
    
63.         dev_err(fbdev->dev, "failed to request io memory region\n");
    
64.         ret = -EINVAL;
    
65.         goto err_io;
    
66.     }
    
67. 
    
68.     /*将LCD的IO端口占用的这段IO空间映射到内存的虚拟地址，ioremap定义在io.h中
    
69.          注意：IO空间要映射后才能使用，以后对虚拟地址的操作就是对IO空间的操作*/
    
70.     fbdev->regs = ioremap(res->start, res->end - res->start + 1);
    
71.     if (!fbdev->regs) {
    
72.         dev_err(fbdev->dev, "failed to remap io region\n");
    
73.         ret = -EINVAL;
    
74.         goto err_mem;
    
75.     }
    
76. #ifdef CONFIG_FB_S3C_LTE480WV
    
77.     /*设置寄存器初始状态*/
    
78.     s3cfb_pre_init_para(fbdev);
    
79. #endif
    
80. 
    
81.     /*设置gamma 值*/
    
82.     s3cfb_set_gamma(fbdev);
    
83.     /*设置VSYNC中断*/
    
84.     s3cfb_set_vsync_interrupt(fbdev, 1);
    
85.     /*设置全局中断*/
    
86.     s3cfb_set_global_interrupt(fbdev, 1);
    
87.     /*fb设备参数信息初始化*/
    
88.     s3cfb_init_global(fbdev);
    
89. 
    
90.     /*为framebuffer分配空间，进行内存映射，填充fb_info*/
    
91.     if (s3cfb_alloc_framebuffer(fbdev)) {
    
92.         ret = -ENOMEM;
    
93.         goto err_alloc;
    
94.     }
    
95. 
    
96.     /*注册fb设备到系统中*/
    
97.     if (s3cfb_register_framebuffer(fbdev)) {
    
98.         ret = -EINVAL;
    
99.         goto err_register;
    
100.     }
     
101. 
     
102.     s3cfb_set_clock(fbdev);
     
103.     s3cfb_set_window(fbdev, pdata->default_win, 1);
     
104. 
     
105.     s3cfb_display_on(fbdev);
     
106. 
     
107.     fbdev->irq = platform_get_irq(pdev, 0);
     
108.     if (request_irq(fbdev->irq, s3cfb_irq_frame, IRQF_SHARED,
     
109.             pdev->name, fbdev)) {
     
110.         dev_err(fbdev->dev, "request_irq failed\n");
     
111.         ret = -EINVAL;
     
112.         goto err_irq;
     
113.     }
     
114. 
     
115. #ifdef CONFIG_FB_S3C_LCD_INIT
     
116.     if (pdata->backlight_on)
     
117.         pdata->backlight_on(pdev);
     
118. 
     
119.     if (!bootloaderfb && pdata->reset_lcd)
     
120.         pdata->reset_lcd(pdev);
     
121. 
     
122.     if (pdata->lcd_on)
     
123.         pdata->lcd_on(pdev);
     
124. #endif
     
125. 
     
126. #ifdef CONFIG_HAS_EARLYSUSPEND
     
127.     fbdev->early_suspend.suspend = s3cfb_early_suspend;
     
128.     fbdev->early_suspend.resume = s3cfb_late_resume;
     
129.     fbdev->early_suspend.level = EARLY_SUSPEND_LEVEL_DISABLE_FB;
     
130.     register_early_suspend(&fbdev->early_suspend);
     
131. #endif
     
132. 
     
133.     /*对设备文件系统的支持，创建fb设备文件*/
     
134.     ret = device_create_file(&(pdev->dev), &dev_attr_win_power);
     
135.     if (ret < 0)
     
136.         dev_err(fbdev->dev, "failed to add sysfs entries\n");
     
137. 
     
138.     dev_info(fbdev->dev, "registered successfully\n");
     
139. 
     
140.     /*显示开机logo*/
     
141. #if !defined(CONFIG_FRAMEBUFFER_CONSOLE) && defined(CONFIG_LOGO)
     
142.     if (fb_prepare_logo( fbdev->fb[pdata->default_win], FB_ROTATE_UR)) {
     
143.         printk("Start display and show logo\n");
     
144.         /* Start display and show logo on boot */
     
145.         fb_set_cmap(&fbdev->fb[pdata->default_win]->cmap, fbdev->fb[pdata->default_win]);
     
146.         fb_show_logo(fbdev->fb[pdata->default_win], FB_ROTATE_UR);
     
147.     }
     
148. #endif
     
149. 
     
150.     return 0;
     
151. }