linux2628下6410LCD驱动分析.docx

1、linux2628下6410LCD驱动分析linux2.6.28下6410LCD驱动分析本文不详细分析lcd的每行代码，只是做简单的构架分析， 要详细的分析可以参考 LCD驱动是用了device 和driver架构，首先看arch/arm/mach-s3c6410/mach-smdk6410.c文件，在353行有这样一个数组static struct platform_device *smdk6410_devices _initdata = &s3c_device_lcd,我们在进里面了解详情，在arch/arm/palt-s3c64xx/devs.c文件里有s3c_device_lcd变量的

2、定义static struct resource s3c_lcd_resource = 0 = .start = S3C64XX_PA_LCD, /lcd寄存器的起始地址.end = S3C64XX_PA_LCD + SZ_1M - 1,/lcd寄存器的结束地址，.flags = IORESOURCE_MEM,1 = .start = IRQ_LCD_VSYNC,/lcd中断寄存器起始地址，在s3cfb_probe用.end = IRQ_LCD_SYSTEM,.flags = IORESOURCE_IRQ,;static u64 s3c_device_lcd_dmamask = 0xfffff

3、fffUL;struct platform_device s3c_device_lcd = .name = s3c-lcd,/这个会和driver中的name一样，driver/根据这个进行匹配.id = -1,.num_resources = ARRAY_SIZE(s3c_lcd_resource),.resource = s3c_lcd_resource,.dev = .dma_mask= &s3c_device_lcd_dmamask,.coherent_dma_mask= 0xffffffffUL;在arch/arm/mach-s3c6410/mach-smdk6410.c文件的sta

4、tic void _init smdk6410_machine_init(void)函数中有这么一句话platform_add_devices(smdk6410_devices, ARRAY_SIZE(smdk6410_devices);这个就是对device设备进行注册，在注册driver驱动时，会根据name找到相应的device进行匹配，然后会调用probe。 下面分析driver，在drivers/video/samsung/s3cfb.c文件的最下面有这样的一段代码static struct platform_driver s3cfb_driver = .probe= s3cfb_p

5、robe, /匹配的话会调用这个函数.remove= s3cfb_remove,.suspend= s3cfb_suspend,.resume= s3cfb_resume, .driver= .name= s3c-lcd,/上面说的，内核会根据这个来找到相应的device.owner= THIS_MODULE,;int _devinit s3cfb_init(void)return platform_driver_register(&s3cfb_driver);/进行drive注册匹配后会掉用s3cfb_probe（）；这个函数里面对fbinfo进行初始化，对相关寄存器进行初始化，在6410l

6、cd驱动中，主要要修改的几个文件是：drivers/video/samsung目录下的s3cfb.c，假设你在配置的时候即用make menuconfig命令，在里面选择的是480WV，他对应的文件时s3cfb_lte480wv.c，s3cfb_lte480wv.c是和屏参数相关的文件。还有个要改的文件是s3cfb_fimd4x.c,这个文件主要是涉及寄存器的一些参数的配置。 主要几个重点：对构架的分析，理清楚各个文件的关系。s3cfb.c中的s3cfb_probe主要是在根据s3cfb_fimd4x.c和s3cfb_lte480wv.c文件来初始fbinfo，并且写相关LCD寄存器。s3cf

7、b_lte480wv.c主要是记录屏的参数，在这里进行修改来满足不同的lcd屏。s3cfb_fimd4x.c是对寄存器的值进行初始化，比如各个窗口的显示模式、颜色表寄存器的模式、各个窗口的控制寄存器，此文件还包含6410对于lcd的特殊功能，用ioctl来进行实现的。fbmem.c这个是fb字符设备驱动，每个窗口都是一个字符设备，在s3cfb_probe中通过调用register_buffer进行注册，注意，里面有一个fb_notifier_call_chain，他最终会调用drivers/video/console/fbcon.c中的fbcon_init，里面会有对logo的调用；fbmem

8、.c文件里还有通用的ioctl功能调用，适合所有带lcd控制器的处理器，这个文件时通用的，每个处理器的fbmem都是一样的，做成了和硬件无关。 lcd驱动简单构架图abcs3c2410_lcd & frame buffer 驱动分析 int _init s3c2410fb_probe(struct device *dev) struct s3c2410fb_info *info; struct fb_info *fbinfo; struct platform_device *pdev = to_platform_device(dev); struct s3c2410fb_hw *mregs;

9、int ret; int irq; int i; mach_info = dev-platform_data;/获取lcd相关寄存器配置信息 if (mach_info = NULL) dev_err(dev,no platform data for lcd, cannot attachn); return -EINVAL; mregs = &mach_info-regs; irq = platform_get_irq(pdev, 0); if (irq par;/调用framebuffer_alloc分配内存的时候，其实顺带分配了struct s3c2410fb_info结构，紧跟struc

10、t fb_info结构的后面，fbinfo-par指针处。 info-fb = fbinfo; dev_set_drvdata(dev, fbinfo); s3c2410fb_init_registers(info);/lcd相关寄存器配置 dprintk(devinitn); strcpy(fbinfo-fix.id, driver_name); /* 配置信息存储起来，以后用到 */ memcpy(&info-regs, &mach_info-regs, sizeof(info-regs); info-mach_info = dev-platform_data; /* 以下配置，详细请参考

11、网上资料 */ fbinfo-fix.type = FB_TYPE_PACKED_PIXELS; fbinfo-fix.type_aux = 0; fbinfo-fix.xpanstep = 0; fbinfo-fix.ypanstep = 0; fbinfo-fix.ywrapstep = 0; fbinfo-fix.accel = FB_ACCEL_NONE; fbinfo-var.nonstd = 0; fbinfo-var.activate = FB_ACTIVATE_NOW; /* 设置分辨率 */ fbinfo-var.height = mach_info-height; fbin

12、fo-var.width = mach_info-width; fbinfo-var.accel_flags = 0; fbinfo-var.vmode = FB_VMODE_NONINTERLACED; fbinfo-fbops = &s3c2410fb_ops;/重要的fop结构(fb设备本质上是字符设备) fbinfo-flags = FBINFO_FLAG_DEFAULT; fbinfo-pseudo_palette = &info-pseudo_pal; fbinfo-var.xres = mach_info-xres.defval; fbinfo-var.xres_virtual

13、= mach_info-xres.defval; fbinfo-var.yres = mach_info-yres.defval; fbinfo-var.yres_virtual = mach_info-yres.defval; fbinfo-var.bits_per_pixel = mach_info-bpp.defval; fbinfo-var.upper_margin = S3C2410_LCDCON2_GET_VBPD(mregs-lcdcon2) +1; fbinfo-var.lower_margin = S3C2410_LCDCON2_GET_VFPD(mregs-lcdcon2)

14、 +1; fbinfo-var.vsync_len = S3C2410_LCDCON2_GET_VSPW(mregs-lcdcon2) + 1; fbinfo-var.left_margin = S3C2410_LCDCON3_GET_HFPD(mregs-lcdcon3) + 1; fbinfo-var.right_margin = S3C2410_LCDCON3_GET_HBPD(mregs-lcdcon3) + 1; fbinfo-var.hsync_len = S3C2410_LCDCON4_GET_HSPW(mregs-lcdcon4) + 1; /* 配色板设置(采用5、6、5模式

15、) */ fbinfo-var.red.offset = 11; fbinfo-var.green.offset = 5; fbinfo-var.blue.offset = 0; fbinfo-var.transp.offset = 0; fbinfo-var.red.length = 5; fbinfo-var.green.length = 6; fbinfo-var.blue.length = 5; fbinfo-var.transp.length = 0; /* 计算需要申请的framer buffer大小(以字节为单位) */ fbinfo-fix.smem_len = mach_in

16、fo-xres.max * mach_info-yres.max * mach_info-bpp.max / 8; for (i = 0; i palette_bufferi = PALETTE_BUFF_CLEAR; if (!request_mem_region(unsigned long)S3C24XX_VA_LCD, SZ_1M, s3c2410-lcd) ret = -EBUSY; goto dealloc_fb; dprintk(got LCD regionn); ret = request_irq(irq, s3c2410fb_irq, SA_INTERRUPT, pdev-na

17、me, info); if (ret) dev_err(dev, cannot get irq %d - err %dn, irq, ret); ret = -EBUSY; goto release_mem; info-clk = clk_get(NULL, lcd); if (!info-clk | IS_ERR(info-clk) printk(KERN_ERR failed to get lcd clock sourcen); ret = -ENOENT; goto release_irq; clk_use(info-clk); clk_enable(info-clk); dprintk

18、(got and enabled clockn); msleep(1); /* Initialize video memory */ ret = s3c2410fb_map_video_memory(info); if (ret) printk( KERN_ERR Failed to allocate video RAM: %dn, ret); ret = -ENOMEM; goto release_clock; dprintk(got video memoryn); ret = s3c2410fb_init_registers(info);/怎么再次初始化lcd相关寄存器了? ret = s

19、3c2410fb_check_var(&fbinfo-var, fbinfo);/注册frame buffer前的一个例行检查 ret = register_framebuffer(fbinfo); if (ret node, fbinfo-fix.id); return 0;free_video_memory: s3c2410fb_unmap_video_memory(info);release_clock: clk_disable(info-clk); clk_unuse(info-clk); clk_put(info-clk);release_irq: free_irq(irq,info

20、);release_mem: release_mem_region(unsigned long)S3C24XX_VA_LCD, S3C24XX_SZ_LCD);dealloc_fb: framebuffer_release(fbinfo); return ret;/* * s3c2410fb_map_video_memory(): * Allocates the DRAM memory for the frame buffer. This buffer is * remapped into a non-cached, non-buffered, memory region to * allow

21、 palette and pixel writes to occur without flushing the * cache. Once this area is remapped, all virtual memory * access to the video memory should occur at the new region. */static int _init s3c2410fb_map_video_memory(struct s3c2410fb_info *fbi) dprintk(map_video_memory(fbi=%p)n, fbi); fbi-map_size

22、 = PAGE_ALIGN(fbi-fb-fix.smem_len + PAGE_SIZE);/页对齐 fbi-map_cpu = dma_alloc_writecombine(fbi-dev, fbi-map_size, &fbi-map_dma, GFP_KERNEL);/目前我只知道用于分配可供dma使用的内存，其中返回地址fbi-map_cpu为虚拟地址,fbi-map_dma为物理地址。 fbi-map_size = fbi-fb-fix.smem_len;/恢复真实的大小 if (fbi-map_cpu) /* prevent initial garbage on screen *

23、/ dprintk(map_video_memory: clear %p:%08xn, fbi-map_cpu, fbi-map_size); memset(fbi-map_cpu, 0xf0, fbi-map_size); fbi-screen_dma = fbi-map_dma;/物理地址 fbi-fb-screen_base = fbi-map_cpu;/虚拟地址 fbi-fb-fix.smem_start = fbi-screen_dma;/物理地址 dprintk(map_video_memory: dma=%08x cpu=%p size=%08xn, fbi-map_dma, f

24、bi-map_cpu, fbi-fb-fix.smem_len); return fbi-map_cpu ? 0 : -ENOMEM;static struct s3c2410fb_mach_info sbc2410_lcdcfg _initdata = .fixed_syncs= 0, .regs= .lcdcon1= S3C2410_LCDCON1_TFT16BPP | S3C2410_LCDCON1_TFT | S3C2410_LCDCON1_CLKVAL(6), .lcdcon2= S3C2410_LCDCON2_VBPD(2) | S3C2410_LCDCON2_LINEVAL(319) | S3C2410_LCDCON2_VFPD(0) | S3C2410_LCDCON2_