Linux的LCD驱动源码分析及移植.doc

Linux的LCD驱动源码分析及移植（三部曲）第一部分：基于ARM9处理器的linux-操作系统内核移植手记part5.1(LCD驱动源码分析及移植之platform device)1.与LCD控制器硬件相关的寄存器内容请参照三星S3C2440A技术手册中的第15章。2.LCD Controller的平台设备定义如下（文件位于 linux/arch/arm/plat-s3c24xx/devs.c）：1. /*LCD Controller*/2.3. static struct resource s3c_lcd_resource=4. 0=5. .start=S3C24XX_PA_LCD,6. .end=S3C24XX_PA_LCD+S3C24XX_SZ_LCD-1,7. .flags=IORESOURCE_MEM,8. ,9. 1=10. .start=IRQ_LCD,11. .end=IRQ_LCD,12. .flags=IORESOURCE_IRQ,13. 14.15. ;16.17. static u64 s3c_device_lcd_dmamask=0xffffffffUL;18.19. struct platform_device s3c_device_lcd=20. .name=s3c2410-lcd,21. .id=-1,22. .num_resources=ARRAY_SIZE(s3c_lcd_resource),23. .resource=s3c_lcd_resource,24. .dev=25. .dma_mask=&s3c_device_lcd_dmamask,26. .coherent_dma_mask=0xffffffffUL27. 28. ;29.30. EXPORT_SYMBOL(s3c_device_lcd);平台设备的结构体定义为s3c_device_lcd，该设备在平台总线中的名字取为s3c2410-lcd，该平台设备申请的两个板级资源为以S3C24XX_PA_LCD为起始的IORESOURCE_MEM资源和一个定义为IRQ_LCD的IORESOURCE_IRQ资源。其中，1. #define S3C24XX_PA_LCD S3C2410_PA_LCD1. /*LCD controller*/2. #define S3C2410_PA_LCD(0x4D000000)3. #define S3C24XX_SZ_LCD SZ_1M0x4D000000为LCDCON1寄存器的地址。3. LCD Controller的平台设备的注册如下（文件位于linux/arch/arm/mach-s3c2440/mach-smdk2440.c）：1. static struct platform_device*smdk2440_devices_initdata=2. &s3c_device_usb,3.4. &s3c_device_lcd,5.6. &s3c_device_wdt,7. &s3c_device_i2c0,8. &s3c_device_iis,9. &s3c_device_rtc,10. ;以上第4行代码将lcd平台设备注册进内核。4.在系统初始化时将smdk2440_fb_info结构体添加进平台设备的私有结构中。具体流程如下：4.11. MACHINE_START(S3C2440,SMDK2440)2. /*Maintainer:Ben Dooks*/3. .phys_io=S3C2410_PA_UART,4. .io_pg_offst=(u32)S3C24XX_VA_UART)18)&0xfffc,5. .boot_params=S3C2410_SDRAM_PA+0x100,6.7. .init_irq=s3c24xx_init_irq,8. .map_io=smdk2440_map_io,9. .init_machine=smdk2440_machine_init,10. .timer=&s3c24xx_timer,11. MACHINE_END启动S3C2440机器，系统将通过“.init_machine=smdk2440_machine_init,”调用smdk2440_machine_init（）函数。4.21. static void _init smdk2440_machine_init(void)2. 3. s3c24xx_fb_set_platdata(&smdk2440_fb_info);4. s3c_i2c0_set_platdata(NULL);5.6. platform_add_devices(smdk2440_devices,ARRAY_SIZE(smdk2440_devices);7. smdk_machine_init();8. 在smdk2440_machine_init函数中，通过“ s3c24xx_fb_set_platdata(&smdk2440_fb_info);”将smdk2440_fb_info添加进平台设备的私有结构中。4.31. void _init s3c24xx_fb_set_platdata(struct s3c2410fb_mach_info*pd)2. 3. struct s3c2410fb_mach_info*npd;4.5. npd=kmalloc(sizeof(*npd),GFP_KERNEL);6. if(npd)7. memcpy(npd,pd,sizeof(*npd);8. s3c_device_lcd.dev.platform_data=npd;9. else10. printk(KERN_ERRno memory for LCD platform datan);11. 12. 以上代码为smdk2440_fb_info结构的添加过程，其中“s3c_device_lcd.dev.platform_data=npd;”为核心实现部分。4.41. static struct s3c2410fb_mach_info smdk2440_fb_info _initdata=2. .displays=&smdk2440_lcd_cfg,3. .num_displays=1,4. .default_display=0,5.6. #if07. /*currently setup by downloader*/8. .gpccon=0xaa940659,9. .gpccon_mask=0xffffffff,10. .gpcup=0x0000ffff,11. .gpcup_mask=0xffffffff,12. .gpdcon=0xaa84aaa0,13. .gpdcon_mask=0xffffffff,14. .gpdup=0x0000faff,15. .gpdup_mask=0xffffffff,16. #endif17.18. /.lpcsel=(0xCE6)&7)|14,19. ;以上为smdk2440_fb_info结构体定义。在此需要注释掉源码中的“.lpcsel=(0xCE6)&7)|1dev.platform_data;16. if(mach_info=NULL)17. dev_err(&pdev-dev,18. no platform data for lcd, cannot attachn);19. return-EINVAL;20. 21.22. if(mach_info-default_display=mach_info-num_displays)23. dev_err(&pdev-dev,default is %d but only %d displaysn,24. mach_info-default_display,mach_info-num_displays);25. return-EINVAL;26. 27.28. display=mach_info-displays+mach_info-default_display;29.30. irq=platform_get_irq(pdev,0);31. if(irqdev,no irq for devicen);33. return-ENOENT;34. 35.36. fbinfo=framebuffer_alloc(sizeof(struct s3c2410fb_info),&pdev-dev);37. if(!fbinfo)38. return-ENOMEM;39.40. platform_set_drvdata(pdev,fbinfo);41.42. info=fbinfo-par;43. info-dev=&pdev-dev;44. info-drv_type=drv_type;45.46. res=platform_get_resource(pdev,IORESOURCE_MEM,0);47. if(res=NULL)48. dev_err(&pdev-dev,failed to get memory registersn);49. ret=-ENXIO;50. goto dealloc_fb;51. 52.53. size=(res-end-res-start)+1;54. info-mem=request_mem_region(res-start,size,pdev-name);55. if(info-mem=NULL)56. dev_err(&pdev-dev,failed to get memory regionn);57. ret=-ENOENT;58. goto dealloc_fb;59. 60.61. info-io=ioremap(res-start,size);62. if(info-io=NULL)63. dev_err(&pdev-dev,ioremap() of registers failedn);64. ret=-ENXIO;65. goto release_mem;66. 67.68. info-irq_base=info-io+(drv_type=DRV_S3C2412)?S3C2412_LCDINTBASE:S3C2410_LCDINTBASE);69.70. dprintk(devinitn);71.72. strcpy(fbinfo-fix.id,driver_name);73.74. /*Stop the video*/75. lcdcon1=readl(info-io+S3C2410_LCDCON1);76. writel(lcdcon1&S3C2410_LCDCON1_ENVID,info-io+S3C2410_LCDCON1);77.78. fbinfo-fix.type=FB_TYPE_PACKED_PIXELS;79. fbinfo-fix.type_aux=0;80. fbinfo-fix.xpanstep=0;81. fbinfo-fix.ypanstep=0;82. fbinfo-fix.ywrapstep=0;83. fbinfo-fix.accel=FB_ACCEL_NONE;84.85. fbinfo-var.nonstd=0;86. fbinfo-var.activate=FB_ACTIVATE_NOW;87. fbinfo-var.accel_flags=0;88. fbinfo-var.vmode=FB_VMODE_NONINTERLACED;89.90. fbinfo-fbops=&s3c2410fb_ops;91. fbinfo-flags=FBINFO_FLAG_DEFAULT;92. fbinfo-pseudo_palette=&info-pseudo_pal;93.94. for(i=0;ipalette_bufferi=PALETTE_BUFF_CLEAR;96.97. ret=request_irq(irq,s3c2410fb_irq,IRQF_DISABLED,pdev-name,info);98. if(ret)99. dev_err(&pdev-dev,cannot get irq %d - err %dn,irq,ret);100. ret=-EBUSY;101. goto release_regs;102. 103.104. info-clk=clk_get(NULL,lcd);105. if(!info-clk|IS_ERR(info-clk)106. printk(KERN_ERRfailed to get lcd clock sourcen);107. ret=-ENOENT;108. goto release_irq;109. 110.111. clk_enable(info-clk);112. dprintk(got and enabled clockn);113.114. msleep(1);115.116. info-clk_rate=clk_get_rate(info-clk);117.118. /*find maximum required memory sizefordisplay*/119. for(i=0;inum_displays;i+)120. unsigned long smem_len=mach_info-displaysi.xres;121.122. smem_len*=mach_info-displaysi.yres;123. smem_len*=mach_info-displaysi.bpp;124. smem_len=3;125. if(fbinfo-fix.smem_lenfix.smem_len=smem_len;127. 128.129. /*Initialize video memory*/130. ret=s3c2410fb_map_video_memory(fbinfo);131. if(ret)132. printk(KERN_ERRFailed to allocate video RAM: %dn,ret);133. ret=-ENOMEM;134. goto release_clock;135. 136.137. dprintk(got video memoryn);138.139. fbinfo-var.xres=display-xres;140. fbinfo-var.yres=display-yres;141. fbinfo-var.bits_per_pixel=display-bpp;142.143. s3c2410fb_init_registers(fbinfo);144.145. s3c2410fb_check_var(&fbinfo-var,fbinfo);146.147. ret=s3c2410fb_cpufreq_register(info);148. if(retdev,Failed to register cpufreqn);150. goto free_video_memory;151. 152.153. ret=register_framebuffer(fbinfo);154. if(retdev,&dev_attr_debug);162. if(ret)163. printk(KERN_ERRfailed to add debug attributen);164. 165.166. printk(KERN_INFOfb%d: %s frame buffer devicen,167. fbinfo-node,fbinfo-fix.id);168.169. return 0;170.171. free_cpufreq:172. s3c2410fb_cpufreq_deregister(info);173. free_video_memory:174. s3c2410fb_unmap_video_memory(fbinfo);175. release_clock:176. clk_disable(info-clk);177. clk_put(info-clk);178. release_irq:179. free_irq(irq,info);180. release_regs:181. iounmap(info-io);182. release_mem:183. release_resource(info-mem);184. kfree(info-mem);185. dealloc_fb:186. platform_set_drvdata(pdev,NULL);187. framebuffer_release(fbinfo);188. return ret;189. 7.11. mach_info=pdev-dev.platform_data;2. if(mach_info=NULL)3. dev_err(&pdev-dev,4. no platform data for lcd, cannot attachn);5. return-EINVAL;6. 7.8. if(mach_info-default_display=mach_info-num_displays)9. dev_err(&pdev-dev,default is %d but only %d displaysn,10. mach_info-default_display,mach_info-num_displays);11. return-EINVAL;12. 13.14. display=mach_info-displays+mach_info-default_display;第一行用于获取platform device中定义的平台数据（已经在本博客的上一篇文章中提及）。其中的mach_info定义如下：1. struct s3c2410fb_mach_info*mach_info;1. struct s3c2410fb_mach_info2.3. struct s3c2410fb_display*displays;/*attached diplays info*/4. unsigned num_displays;/*number of defined displays*/5. unsigned default_display;6.7. /*GPIOs*/8.9. unsigned longgpcup;10. unsigned longgpcup_mask;11. unsigned longgpccon;12. unsigned longgpccon_mask;13. unsigned longgpdup;14. unsigned longgpdup_mask;15. unsigned longgpdcon;16. unsigned longgpdcon_mask;17.18. /*lpc3600 control register*/19. unsigned longlpcsel;20. ;主要是记录LCD的一些属性，包括与显示参数相关的“ struct s3c2410fb_display*displays;”及使用的GPIO引脚。而”if(mach_info-default_display=mach_info-num_displays).“用来查看显示屏幕的具体规格。7.21. irq=platform_get_irq(pdev,0);2. if(irqdev,no irq for devicen);4. return-ENOENT;5. 获取设备中断号（定义于mach-smdk2440.c中）。7.31. fbinfo=framebuffer_alloc(sizeof(struct s3c2410fb_info),&pdev-dev);2. if(!fbinfo)3. return-ENOMEM;4.5. platform_set_drvdata(pdev,fbinfo);在内存中申请sizeof(struct s3c2410fb_info)+sizeof(struct fb_info)大小的空间，然后将获得的fbinfo设置为平台设备的驱动数据。其中framebuffer_alloc源码如下：1. /*2. *framebuffer_alloc-creates a new frame buffer info structure3. *4. *size:size of driverprivatedata,can be zero5. *dev:pointertothe deviceforthis fb,this can beNULL6. *7. *Creates a new frame buffer info structure.Also reserves size bytes8. *fordriverprivatedata(info-par).info-par(ifany)will be9. *alignedtosizeof(long).10. *11. *Returns the new structure,orNULLifanerroroccured.12. *13. */14. struct fb_info*framebuffer_alloc(size_t size,struct device*dev)15. 16. #define BYTES_PER_LONG(BITS_PER_LONG/8)17. #define PADDING(BYTES_PER_LONG-(sizeof(struct fb_info)%BYTES_PER_LONG)18. intfb_info_size=sizeof(struct fb_info);19. struct fb_info*info;20. char*p;21.22. if(size)23. fb_info_size+=PADDING;24.25. p=kzalloc(fb_info_size+size,GFP_KERNEL);26.27. if(!p)28. returnNULL;29.30. info=(struct fb_info*)p;31.32. if(size)33. info-par=p+fb_info_size;34.35. info-device=dev;36.37. #ifdef CONFIG_FB_BACKLIGHT38. mutex_init(&info-bl_curve_mutex);39. #endif40.41. return info;42. #undef PADDING43. #undef BYTES_PER_LONG44. 45. EXPORT_SYMBOL(framebuffer_alloc);其中platform_set_drvdata宏如下：1. #define platform_set_drvdata(_dev,data)dev_set_drvdata(&(_dev)-dev,(data)7.41. info=fbinfo-par;2. info-dev=&pdev-dev;3. info-drv_type=drv_type;设置驱动数据。7.51. res=platform_get_resource(pdev,IORESOURCE_MEM,0);2. if(res=NULL)3. dev_err(&pdev-dev,failed to get memory registersn);4. ret=-ENXIO;5. goto dealloc_fb;6. 7.8. size=(res-end-res-start)+1;9. info-mem=request_mem_region(res-start,size,pdev-name);10. if(info-mem=NULL)11. dev_err(&pdev-dev,failed to get memory regionn);12. ret=-ENOENT;13. goto dealloc_fb;14. 15.16. info-io=ioremap(res-start,size);17. if(info-io=NULL)18. dev_err(&pdev-dev,ioremap() of registers failedn);19. ret=-ENXIO;20. goto release_mem;21. 映射内核资源（IO口，中断号，硬件地址转虚拟地址）。7.61. lcdcon1=readl(info-io+S3C2410_LCDCON1);2. writel(lcdcon1&S3C2410_LCDCON1_ENVID,info-io+S3C2410_LCDCON1);关闭显示屏幕7.71. fbinfo-fix.type=FB_TYPE_PACKED_PIXELS;2. fbinfo-fix.type_aux=0;3. fbinfo-fix.xpanstep=0;4. fbinfo-fix.ypanstep=0;5. fbinfo-fix.ywrapstep=0;6. fbinfo-fix.accel=FB_ACCEL_NONE;7.8. fbinfo-var.nonstd=0;9. fbinfo-var.activate=FB_ACTIVATE_NOW;10. fbinfo-var.accel_flags=0;11. fbinfo-var.vmode=FB_VMODE_NONINTERLACED;12.13. fbinfo-fbops=&s3c2410fb_ops;14. fbinfo-flags=FBINFO_FLAG_DEFAULT;15. fbinfo-pseudo_palette=&info-pseudo_pal;16.17. for(i=0;ipalette_bufferi=PALETTE_BUFF_CLEAR;对fbinfo进行赋值。7.81. ret=request_irq(irq,s3c2410fb_irq,IRQF_DISABLED,pdev-name,info);2. if(ret)