Linux驱动修炼之道-framebuffer（中）
努力成为linux kernel hacker的人李万鹏原创作品，为梦而战。转载请标明出处http://blog.csdn.net/woshixingaaa/archive/2011/05/29/6452689.aspx
下面详细分析一下framebuffer的驱动源码,framebuffer作为一个平台驱动注册进内核：
static struct platform_driver s3c2410fb_driver = {.probe= s3c2410fb_probe,.remove= s3c2410fb_remove,.suspend= s3c2410fb_suspend,.resume= s3c2410fb_resume,.driver= {.name= "s3c2410-lcd",.owner= THIS_MODULE,},};int __init s3c2410fb_init(void){int ret = platform_driver_register(&s3c2410fb_driver);if (ret == 0)ret = platform_driver_register(&s3c2412fb_driver);;return ret;}static void __exit s3c2410fb_cleanup(void){platform_driver_unregister(&s3c2410fb_driver);platform_driver_unregister(&s3c2412fb_driver);}module_init(s3c2410fb_init);module_exit(s3c2410fb_cleanup);
在arch/arm/plat-s3c24xx/devs.c中定义了framebuffer的平台设备：
/* LCD Controller */static struct resource s3c_lcd_resource[] = { = {.start = S3C24XX_PA_LCD, //IO内存的物理起始地址.end = S3C24XX_PA_LCD + S3C24XX_SZ_LCD - 1, //IO内存的物理结束地址 .flags = IORESOURCE_MEM, }, = {.start = IRQ_LCD, //LCD的中断号.end = IRQ_LCD,.flags = IORESOURCE_IRQ,}};static u64 s3c_device_lcd_dmamask = 0xffffffffUL;struct platform_device s3c_device_lcd = {.name= "s3c2410-lcd",.id= -1,.num_resources= ARRAY_SIZE(s3c_lcd_resource),.resource= s3c_lcd_resource,.dev = {.dma_mask= &s3c_device_lcd_dmamask,.coherent_dma_mask= 0xffffffffUL}};EXPORT_SYMBOL(s3c_device_lcd);
devs.c中的这个函数把s3c2410fb_mach_info存放到s3c_device_lcd.dev.platform_data，probe函数中会用到的。
void __init s3c24xx_fb_set_platdata(struct s3c2410fb_mach_info *pd){struct s3c2410fb_mach_info *npd;npd = kmalloc(sizeof(*npd), GFP_KERNEL);if (npd) {memcpy(npd, pd, sizeof(*npd));s3c_device_lcd.dev.platform_data = npd;} else {printk(KERN_ERR "no memory for LCD platform data\n");}}
这个函数是在arch/arm/mach-s3c2440/mach-smdk2440.c中的smdk2440_machine_init中调用的，所以在系统启动后会自动调用。
static void __init smdk2440_machine_init(void){s3c24xx_fb_set_platdata(&smdk2440_fb_info);s3c_i2c0_set_platdata(NULL);platform_add_devices(smdk2440_devices, ARRAY_SIZE(smdk2440_devices));smdk_machine_init();}
s3c2410fb_display表示屏的显示参数，这个结构体在我们移植LCD驱动的时候需要根据我们屏的参数重新设置。
/* LCD driver info */static struct s3c2410fb_display smdk2440_lcd_cfg __initdata = {.lcdcon5= S3C2410_LCDCON5_FRM565 |S3C2410_LCDCON5_INVVLINE |S3C2410_LCDCON5_INVVFRAME |S3C2410_LCDCON5_PWREN |S3C2410_LCDCON5_HWSWP,.type= S3C2410_LCDCON1_TFT,.width= 240,.height= 320,.pixclock= 270000, .xres= 320,.yres= 240,.bpp= 16,.left_margin= 8,.right_margin= 5,.hsync_len= 63,.upper_margin= 15,.lower_margin= 3,.vsync_len= 5,};
将s3c2410fb_display结构体存于s3c2410fb_mach_info的displays域。
static struct s3c2410fb_mach_info smdk2440_fb_info __initdata = {.displays= &smdk2440_lcd_cfg,.num_displays= 1,.default_display = 0,.lpcsel = 0,};
下面来看看当lcd驱动和设备匹配成功后会调用的探测函数：
static int __init s3c2410fb_probe(struct platform_device *pdev){return s3c24xxfb_probe(pdev, DRV_S3C2410);}
这里调用了s3c24xxfb_probe(pdev, DRV_S3C2410)，进行了一层封装，因为这样这部分代码可以与s3c2412进行复用。
static int __init s3c24xxfb_probe(struct platform_device *pdev,enum s3c_drv_type drv_type){struct s3c2410fb_info *info;struct s3c2410fb_display *display;struct fb_info *fbinfo;struct s3c2410fb_mach_info *mach_info;struct resource *res;int ret;int irq;int i;int size;u32 lcdcon1;/*这就获得了刚才保存的s3c2410fb_mach_info*/mach_info = pdev->dev.platform_data;if (mach_info == NULL) {dev_err(&pdev->dev,"no platform data for lcd, cannot attach\n");return -EINVAL;}if (mach_info->default_display >= mach_info->num_displays) {dev_err(&pdev->dev, "default is %d but only %d displays\n",mach_info->default_display, mach_info->num_displays);return -EINVAL;}/*获取显示屏的相关参数*/display = mach_info->displays + mach_info->default_display;/*获得中断号*/irq = platform_get_irq(pdev, 0);if (irq < 0) {dev_err(&pdev->dev, "no irq for device\n");return -ENOENT;}/*分配一个fb_info结构体*/fbinfo = framebuffer_alloc(sizeof(struct s3c2410fb_info), &pdev->dev);if (!fbinfo)return -ENOMEM;/*设置pdev->dev->driver_data保存fbinfo的地址*/platform_set_drvdata(pdev, fbinfo);info = fbinfo->par;info->dev = &pdev->dev;info->drv_type = drv_type;这4句构建的关系图如下:/*获得IO内存*/res = platform_get_resource(pdev, IORESOURCE_MEM, 0);if (res == NULL) {dev_err(&pdev->dev, "failed to get memory registers\n");ret = -ENXIO;goto dealloc_fb;}size = (res->end - res->start) + 1;/*申请IO内存*/info->mem = request_mem_region(res->start, size, pdev->name);if (info->mem == NULL) {dev_err(&pdev->dev, "failed to get memory region\n");ret = -ENOENT;goto dealloc_fb;}/*映射IO内存*/info->io = ioremap(res->start, size);if (info->io == NULL) {dev_err(&pdev->dev, "ioremap() of registers failed\n");ret = -ENXIO;goto release_mem;}/*获得LCD中断挂起寄存器的基地址*/info->irq_base = info->io + ((drv_type == DRV_S3C2412) ? S3C2412_LCDINTBASE : S3C2410_LCDINTBASE);dprintk("devinit\n");strcpy(fbinfo->fix.id, driver_name);/*暂时关闭LCD控制器*/lcdcon1 = readl(info->io + S3C2410_LCDCON1);writel(lcdcon1 & ~S3C2410_LCDCON1_ENVID, info->io + S3C2410_LCDCON1);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;fbinfo->var.accel_flags = 0;fbinfo->var.vmode = FB_VMODE_NONINTERLACED;/*将底层操作函数与上层联系起来*/fbinfo->fbops = &s3c2410fb_ops;fbinfo->flags = FBINFO_FLAG_DEFAULT;fbinfo->pseudo_palette = &info->pseudo_pal;/*用于填充调色板*/for (i = 0; i < 256; i++)info->palette_buffer = PALETTE_BUFF_CLEAR;/*注册中断处理函数*/ret = request_irq(irq, s3c2410fb_irq, IRQF_DISABLED, pdev->name, info);if (ret) {dev_err(&pdev->dev, "cannot get irq %d - err %d\n", irq, ret);ret = -EBUSY;goto release_regs;}/*获得LCD时钟*/info->clk = clk_get(NULL, "lcd");if (!info->clk || IS_ERR(info->clk)) {printk(KERN_ERR "failed to get lcd clock source\n");ret = -ENOENT;goto release_irq;}/*使能LCD时钟*/clk_enable(info->clk);dprintk("got and enabled clock\n");/*初始化LCD控制器之前要延时一段时间*/msleep(1);/*计算缓冲区需要的最大内存，就是缓冲区一共占多少字节，xres*yres*bpp/8 */for (i = 0; i < mach_info->num_displays; i++) {unsigned long smem_len = mach_info->displays.xres;smem_len *= mach_info->displays.yres;smem_len *= mach_info->displays.bpp;smem_len >>= 3;if (fbinfo->fix.smem_len < smem_len)fbinfo->fix.smem_len = smem_len;}/*申请帧缓冲内存*/ret = s3c2410fb_map_video_memory(fbinfo);if (ret) {printk(KERN_ERR "Failed to allocate video RAM: %d\n", ret);ret = -ENOMEM;goto release_clock;}dprintk("got video memory\n");fbinfo->var.xres = display->xres;fbinfo->var.yres = display->yres;fbinfo->var.bits_per_pixel = display->bpp;/*初始化相关寄存器*/s3c2410fb_init_registers(fbinfo);/*检查fb_info中的可变参数*/s3c2410fb_check_var(&fbinfo->var, fbinfo);ret = register_framebuffer(fbinfo); //注册帧缓冲设备if (ret < 0) {printk(KERN_ERR "Failed to register framebuffer device: %d\n",ret);goto free_video_memory;}/* create device files */ret = device_create_file(&pdev->dev, &dev_attr_debug);//创建设备文件if (ret) {printk(KERN_ERR "failed to add debug attribute\n");}printk(KERN_INFO "fb%d: %s frame buffer device\n",fbinfo->node, fbinfo->fix.id);return 0;free_video_memory:s3c2410fb_unmap_video_memory(fbinfo);release_clock:clk_disable(info->clk);clk_put(info->clk);release_irq:free_irq(irq, info);release_regs:iounmap(info->io);release_mem:release_resource(info->mem);kfree(info->mem);dealloc_fb:platform_set_drvdata(pdev, NULL);framebuffer_release(fbinfo);return ret;}
总结一下探测函数完成的任务：
1）申请fb_info结构体的内存空间，初始化fb_info结构中固定和可变的内存参数，即填充fb_info中的fb_var_screeninfo var和struct fb_fix_screeninfo fix成员。
2）申请帧缓冲设备的显示缓冲区空间
3）注册帧缓冲设备
struct fb_info *framebuffer_alloc(size_t size, struct device *dev){#define BYTES_PER_LONG (BITS_PER_LONG/8)#define PADDING (BYTES_PER_LONG - (sizeof(struct fb_info) % BYTES_PER_LONG))int fb_info_size = sizeof(struct fb_info);struct fb_info *info;char *p;if (size)fb_info_size += PADDING;/*这里开辟的堆空间用来存储struct fb_info结构体和struct s3c2410fb_info结构体*/p = kzalloc(fb_info_size + size, GFP_KERNEL);if (!p)return NULL;info = (struct fb_info *) p;/*在这里将par成员赋值，以后用于存储struct s3c2410fb_info结构*/if (size)info->par = p + fb_info_size;info->device = dev;#ifdef CONFIG_FB_BACKLIGHTmutex_init(&info->bl_curve_mutex);#endifreturn info;#undef PADDING#undef BYTES_PER_LONG}
中断处理函数：
static irqreturn_t s3c2410fb_irq(int irq, void *dev_id){struct s3c2410fb_info *fbi = dev_id;/*LCD中断挂起寄存器基地址*/void __iomem *irq_base = fbi->irq_base;/*读取LCD中断挂起寄存器值*/unsigned long lcdirq = readl(irq_base + S3C24XX_LCDINTPND);/*如果framebuffer发出了中断请求*/if (lcdirq & S3C2410_LCDINT_FRSYNC) {/*填充调色板*/if (fbi->palette_ready)s3c2410fb_write_palette(fbi);/*设置帧已插入中断请求*/writel(S3C2410_LCDINT_FRSYNC, irq_base + S3C24XX_LCDINTPND);writel(S3C2410_LCDINT_FRSYNC, irq_base + S3C24XX_LCDSRCPND);}return IRQ_HANDLED;}
填充调色板:
static void s3c2410fb_write_palette(struct s3c2410fb_info *fbi){unsigned int i;void __iomem *regs = fbi->io;fbi->palette_ready = 0;for (i = 0; i < 256; i++) {unsigned long ent = fbi->palette_buffer;if (ent == PALETTE_BUFF_CLEAR)continue;writel(ent, regs + S3C2410_TFTPAL(i));/* it seems the only way to know exactly * if the palette wrote ok, is to check * to see if the value verifies ok */if (readw(regs + S3C2410_TFTPAL(i)) == ent)fbi->palette_buffer = PALETTE_BUFF_CLEAR;elsefbi->palette_ready = 1; /* retry */}}
申请帧缓冲设备fb_info的缓冲区空间：
static int __init s3c2410fb_map_video_memory(struct fb_info *info){struct s3c2410fb_info *fbi = info->par;dma_addr_t map_dma;/*获得帧缓冲区的大小*/unsigned map_size = PAGE_ALIGN(info->fix.smem_len);dprintk("map_video_memory(fbi=%p) map_size %u\n", fbi, map_size);/*分配一个写合并缓冲区来设置帧缓冲的虚拟地址*/info->screen_base = dma_alloc_writecombine(fbi->dev, map_size, &map_dma, GFP_KERNEL);if (info->screen_base) {/* prevent initial garbage on screen */dprintk("map_video_memory: clear %p:%08x\n",info->screen_base, map_size);/*初始化为0*/memset(info->screen_base, 0x00, map_size); /*设置物理地址*/info->fix.smem_start = map_dma;dprintk("map_video_memory: dma=%08lx cpu=%p size=%08x\n",info->fix.smem_start, info->screen_base, map_size);}/*返回虚拟地址*/return info->screen_base ? 0 : -ENOMEM;}
初始化相关寄存器：
static int s3c2410fb_init_registers(struct fb_info *info){struct s3c2410fb_info *fbi = info->par;struct s3c2410fb_mach_info *mach_info = fbi->dev->platform_data;unsigned long flags;/*获得LCD寄存器基地址，这个在probe中获得*/void __iomem *regs = fbi->io;void __iomem *tpal;void __iomem *lpcsel;if (is_s3c2412(fbi)) {tpal = regs + S3C2412_TPAL;lpcsel = regs + S3C2412_TCONSEL;} else {/*获得LCD调色板寄存器基地址，注意对于lpcsel这是一个针对三星TFT屏的一个专用寄存器，如果用的不是三星的屏就不用管它*/tpal = regs + S3C2410_TPAL;lpcsel = regs + S3C2410_LPCSEL;}/* Initialise LCD with values from haret *//*关中断*/local_irq_save(flags);/* modify the gpio(s) with interrupts set (bjd) *//*把IO端口C和D设置成LCD模式*/modify_gpio(S3C2410_GPCUP,mach_info->gpcup,mach_info->gpcup_mask);modify_gpio(S3C2410_GPCCON, mach_info->gpccon, mach_info->gpccon_mask);modify_gpio(S3C2410_GPDUP,mach_info->gpdup,mach_info->gpdup_mask);modify_gpio(S3C2410_GPDCON, mach_info->gpdcon, mach_info->gpdcon_mask);/*恢复被屏蔽的中断*/local_irq_restore(flags);dprintk("LPCSEL = 0x%08lx\n", mach_info->lpcsel);writel(mach_info->lpcsel, lpcsel);dprintk("replacing TPAL %08x\n", readl(tpal));/*临时调色板使能禁止*/writel(0x00, tpal);return 0;}
设置fb_info中的可变参数:
static int s3c2410fb_check_var(struct fb_var_screeninfo *var, struct fb_info *info){struct s3c2410fb_info *fbi = info->par;struct s3c2410fb_mach_info *mach_info = fbi->dev->platform_data;struct s3c2410fb_display *display = NULL;struct s3c2410fb_display *default_display = mach_info->displays + mach_info->default_display;/*LCD的类型，S3C2410_LCDCON1_TFT*/int type = default_display->type;unsigned i;dprintk("check_var(var=%p, info=%p)\n", var, info);/*获取与LCD屏有关的参数，封装在s3c2410fb_display中*/if (var->yres == default_display->yres && var->xres == default_display->xres && var->bits_per_pixel == default_display->bpp)display = default_display;elsefor (i = 0; i < mach_info->num_displays; i++)if (type == mach_info->displays.type && var->yres == mach_info->displays.yres && var->xres == mach_info->displays.xres && var->bits_per_pixel == mach_info->displays.bpp) {display = mach_info->displays + i;break;}if (!display) {dprintk("wrong resolution or depth %dx%d at %d bpp\n",var->xres, var->yres, var->bits_per_pixel);return -EINVAL;}/*配置屏的虚拟解析度和高度宽度*/var->xres_virtual = display->xres;var->yres_virtual = display->yres;var->height = display->height;var->width = display->width;/*这里是时序了，设置时钟像素，行帧切换值，水平同步，垂直同步切换值*/var->pixclock = display->pixclock;var->left_margin = display->left_margin;var->right_margin = display->right_margin;var->upper_margin = display->upper_margin;var->lower_margin = display->lower_margin;var->vsync_len = display->vsync_len;var->hsync_len = display->hsync_len;/*配置LCD控制寄存器1中5-6位(配置成TFT类型)，配置寄存器5*/fbi->regs.lcdcon5 = display->lcdcon5;/* set display type */fbi->regs.lcdcon1 = display->type;/*设置透明度*/var->transp.offset = 0;var->transp.length = 0;/*根据色位模式设置(BPP)来设置可变参数中R,G,B的颜色位域,显示缓冲区与显示点对应如下图：*/
http://hi.csdn.net/attachment/201106/5/0_1307318195M6kP.gif
http://hi.csdn.net/attachment/201106/5/0_1307318217fFFU.gif
switch (var->bits_per_pixel) {case 1:case 2:case 4:var->red.offset= 0;var->red.length= var->bits_per_pixel;var->green= var->red;var->blue= var->red;break;case 8:if (display->type != S3C2410_LCDCON1_TFT) {/* 8 bpp 332 */var->red.length= 3;var->red.offset= 5;var->green.length= 3;var->green.offset= 2;var->blue.length= 2;var->blue.offset= 0;} else {var->red.offset= 0;var->red.length= 8;var->green= var->red;var->blue= var->red;}break;case 12:/* 12 bpp 444 */var->red.length= 4;var->red.offset= 8;var->green.length= 4;var->green.offset= 4;var->blue.length= 4;var->blue.offset= 0;break;default:case 16:if (display->lcdcon5 & S3C2410_LCDCON5_FRM565) {/* 16 bpp, 565 format */var->red.offset= 11;var->green.offset= 5;var->blue.offset= 0;var->red.length= 5;var->green.length= 6;var->blue.length= 5;} else {/* 16 bpp, 5551 format */var->red.offset= 11;var->green.offset= 6;var->blue.offset= 1;var->red.length= 5;var->green.length= 5;var->blue.length= 5;}break;case 32:/* 24 bpp 888 and 8 dummy */var->red.length= 8;var->red.offset= 16;var->green.length= 8;var->green.offset= 8;var->blue.length= 8;var->blue.offset= 0;break;}return 0;}
注册帧缓冲设备:
intregister_framebuffer(struct fb_info *fb_info){int i;struct fb_event event;struct fb_videomode mode;if (num_registered_fb == FB_MAX)return -ENXIO;if (fb_check_foreignness(fb_info))return -ENOSYS;/* *每一个注册的fb_info,都会分配一个下标"i"，对应的就是registered_fb *最多能注册的fb_info个数为FB_MAX,若新注册FB则num_registered_fb++ */num_registered_fb++;for (i = 0 ; i < FB_MAX; i++)if (!registered_fb)break;/*找到空闲的i，赋值给fb_info->node,这个node相当于次设备号了，以后通过这个i找到fb_info*/fb_info->node = i;mutex_init(&fb_info->lock);/*创建设备文件*/fb_info->dev = device_create(fb_class, fb_info->device, MKDEV(FB_MAJOR, i), NULL, "fb%d", i);if (IS_ERR(fb_info->dev)) {/* Not fatal */printk(KERN_WARNING "Unable to create device for framebuffer %d; errno = %ld\n", i, PTR_ERR(fb_info->dev));fb_info->dev = NULL;} else/*初始化fb的属性文件*/fb_init_device(fb_info);。。。。。。。。。。。。。。return 0;}static struct fb_ops s3c2410fb_ops = {.owner= THIS_MODULE,.fb_check_var= s3c2410fb_check_var,.fb_set_par= s3c2410fb_set_par,.fb_blank= s3c2410fb_blank,.fb_setcolreg= s3c2410fb_setcolreg,.fb_fillrect= cfb_fillrect,.fb_copyarea= cfb_copyarea,.fb_imageblit= cfb_imageblit,};
设置参数，根据可变参数设置固定参数：
static int s3c2410fb_set_par(struct fb_info *info){struct fb_var_screeninfo *var = &info->var;/*根据可变参数的位色模式*/switch (var->bits_per_pixel) {case 32:case 16:case 12://设置成真彩，分红，绿，蓝三基色info->fix.visual = FB_VISUAL_TRUECOLOR;break;case 1://设置为黑白，FB_VISUAL_MONO01代表黑，FB_VISUAL_MONO10代表白info->fix.visual = FB_VISUAL_MONO01;break;default://默认设置为伪彩色，采用索引颜色显示info->fix.visual = FB_VISUAL_PSEUDOCOLOR;break;}/*设置fb_info中固定参数一行的字节数*/info->fix.line_length = (var->xres_virtual * var->bits_per_pixel) / 8;/*激活新的参数配置，设置控制寄存器的值*/s3c2410fb_activate_var(info);return 0;}
激活设置：
static void s3c2410fb_activate_var(struct fb_info *info){struct s3c2410fb_info *fbi = info->par;void __iomem *regs = fbi->io;/*获得屏的类型*/int type = fbi->regs.lcdcon1 & S3C2410_LCDCON1_TFT;struct fb_var_screeninfo *var = &info->var;/*获得CLKVAL*/int clkdiv = s3c2410fb_calc_pixclk(fbi, var->pixclock) / 2;dprintk("%s: var->xres= %d\n", __func__, var->xres);dprintk("%s: var->yres= %d\n", __func__, var->yres);dprintk("%s: var->bpp = %d\n", __func__, var->bits_per_pixel);if (type == S3C2410_LCDCON1_TFT) {/*就是根据可变参数结构设置lcdcon1~5*/s3c2410fb_calculate_tft_lcd_regs(info, &fbi->regs);--clkdiv;if (clkdiv < 0)clkdiv = 0;} else {s3c2410fb_calculate_stn_lcd_regs(info, &fbi->regs);if (clkdiv < 2)clkdiv = 2;}/*设置分频值*/fbi->regs.lcdcon1 |=S3C2410_LCDCON1_CLKVAL(clkdiv);/* write new registers */dprintk("new register set:\n");dprintk("lcdcon = 0x%08lx\n", fbi->regs.lcdcon1);dprintk("lcdcon = 0x%08lx\n", fbi->regs.lcdcon2);dprintk("lcdcon = 0x%08lx\n", fbi->regs.lcdcon3);dprintk("lcdcon = 0x%08lx\n", fbi->regs.lcdcon4);dprintk("lcdcon = 0x%08lx\n", fbi->regs.lcdcon5);/*设置寄存器前先把LCD使能关闭，然后将刚才设置的值写入真正的寄存器*/writel(fbi->regs.lcdcon1 & ~S3C2410_LCDCON1_ENVID,regs + S3C2410_LCDCON1);writel(fbi->regs.lcdcon2, regs + S3C2410_LCDCON2);writel(fbi->regs.lcdcon3, regs + S3C2410_LCDCON3);writel(fbi->regs.lcdcon4, regs + S3C2410_LCDCON4);writel(fbi->regs.lcdcon5, regs + S3C2410_LCDCON5);/*设置LCDSADDR1～3*/s3c2410fb_set_lcdaddr(info);/*使能LCD*/fbi->regs.lcdcon1 |= S3C2410_LCDCON1_ENVID,writel(fbi->regs.lcdcon1, regs + S3C2410_LCDCON1);}
显示空白：blank_mode有5中模式，是一个枚举，定义在include/linux/fb.h中：
static int s3c2410fb_blank(int blank_mode, struct fb_info *info){struct s3c2410fb_info *fbi = info->par;void __iomem *tpal_reg = fbi->io;dprintk("blank(mode=%d, info=%p)\n", blank_mode, info);tpal_reg += is_s3c2412(fbi) ? S3C2412_TPAL : S3C2410_TPAL;if (blank_mode == FB_BLANK_POWERDOWN) { //如果是空白模式，则关闭LCDs3c2410fb_lcd_enable(fbi, 0);} else {s3c2410fb_lcd_enable(fbi, 1);}if (blank_mode == FB_BLANK_UNBLANK)/*临时调色板无效*/writel(0x0, tpal_reg);else {/*临时调色板有效*/dprintk("setting TPAL to output 0x000000\n");writel(S3C2410_TPAL_EN, tpal_reg);}return 0;}
设置颜色表：
static int s3c2410fb_setcolreg(unsigned regno, unsigned red, unsigned green, unsigned blue, unsigned transp, struct fb_info *info){struct s3c2410fb_info *fbi = info->par;void __iomem *regs = fbi->io;unsigned int val;/* dprintk("setcol: regno=%d, rgb=%d,%d,%d\n", regno, red, green, blue); */switch (info->fix.visual) {/*真彩色*/case FB_VISUAL_TRUECOLOR:/* true-colour, use pseudo-palette */if (regno < 16) {u32 *pal = info->pseudo_palette;val= chan_to_field(red, &info->var.red);val |= chan_to_field(green, &info->var.green);val |= chan_to_field(blue,&info->var.blue);pal = val;}break;/*伪彩色*/case FB_VISUAL_PSEUDOCOLOR:if (regno < 256) {/* currently assume RGB 5-6-5 mode */val= (red >>0) & 0xf800;val |= (green >>5) & 0x07e0;val |= (blue>> 11) & 0x001f;writel(val, regs + S3C2410_TFTPAL(regno));/*修改调色板*/schedule_palette_update(fbi, regno, val);}break;default:return 1;/* unknown type */}return 0;}static inline unsigned int chan_to_field(unsigned int chan, struct fb_bitfield *bf){chan &= 0xffff;chan >>= 16 - bf->length;return chan << bf->offset;}
修改调色板:
static void schedule_palette_update(struct s3c2410fb_info *fbi, unsigned int regno, unsigned int val){unsigned long flags;unsigned long irqen;/*LCD中断挂起寄存器基地址*/void __iomem *irq_base = fbi->irq_base;/*屏蔽中断，将中断状态保存在flags中*/local_irq_save(flags);fbi->palette_buffer = val;/*判断调色板是否准备就绪*/if (!fbi->palette_ready) {fbi->palette_ready = 1;/*使能中断屏蔽寄存器*/irqen = readl(irq_base + S3C24XX_LCDINTMSK);irqen &= ~S3C2410_LCDINT_FRSYNC;writel(irqen, irq_base + S3C24XX_LCDINTMSK);}/*回复被屏蔽的中断*/local_irq_restore(flags);}
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