学习笔记 --- LINUX LCD显示原理与驱动分析

在分析驱动之前，先来分析下显示原理，这里以S3C2440为例，看下这个芯片的LCD控制器时序图：

VSYNC ：帧数据脉冲，脉冲换屏，表示一屏数据开始

HSYNC ：行数据脉冲，脉冲换行，表示一行数据开始

LEND ：行结束脉冲，脉冲表示一行结束

VDEN ：数据使能，表示VD可以发数据

VCLK  ：基准时钟，脉冲送往数据线送一次数据

VD ：数据

这些都是硬件管脚信号线，从图中可以看出一行中有效数据是HOZVAL+1个像素，(HSPW+1)+(HBPD+1)是屏幕左边黑框的像素，HFPD+1是屏幕右边黑框的像素，一般设置为左边等于右边，上边等于下边，iphone手机有很明显的黑框。那么上边就是(VSPW+1)+(VBPD+1)行，下边就是VFPD+1行，中间有效数据是LINEVAL+1行。假设LCD为240X320那么时序对应的显示图像就是(截图自韦东山老师)：

外面的大框表示LCD黑框，里面表示真正显示的有效数据240X320。接下来说下显示16bpp图像的原理：

16bpp图像意思就是一个像素要用16个位来表示，那么就有2的16次方种颜色，一个像素16位，占2个字节，一屏240X320像素，那么一屏数据占240X320X2个字节，所以显存至少要这么大的空间。一个像素由红绿蓝三原色构成，所以这两个字节包含了红绿蓝三种颜色的信息，他们的占用bit数的比率为5：6：5，也可以是5：5：5，先只说5：6：5格式的，5+6+5=16bit，高位到低位分别表示5位红色，6位绿色，5位蓝色组成了一个两字节数据放在显存区里面，然后LCD控制器将其搬到LCD上显示出来，他们在显存里面的存放有两种方式：

一般选择下面这种方式，先放低16位，再放高16位，S3C2440默认是小端存储，所以这样低位对应低地址，刚好可以对应起来；那么从显存传输到LCD时数据线[0-23]传输的格式如何？

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分析了原理，下面看驱动，LCD的驱动核心在内核fbmem.c里面，分析驱动从入口开始：

static int __init fbmem_init(void){proc_create("fb", 0, NULL, &fb_proc_fops);if (register_chrdev(FB_MAJOR,"fb",&fb_fops)) //注册为字符设备驱动，主设备号为FB_MAJORprintk("unable to get major %d for fb devs\n", FB_MAJOR);fb_class = class_create(THIS_MODULE, "graphics");  //创建类if (IS_ERR(fb_class)) {printk(KERN_WARNING "Unable to create fb class; errno = %ld\n", PTR_ERR(fb_class));fb_class = NULL;}return 0;}

可以知道LCD驱动也就是一个字符设备驱动而已，这个框架已经熟悉了，再看下fops部分：

static const struct file_operations fb_fops = {.owner =THIS_MODULE,.read =fb_read,.write =fb_write,.unlocked_ioctl = fb_ioctl,#ifdef CONFIG_COMPAT.compat_ioctl = fb_compat_ioctl,#endif.mmap =fb_mmap,.open =fb_open,.release =fb_release,#ifdef HAVE_ARCH_FB_UNMAPPED_AREA.get_unmapped_area = get_fb_unmapped_area,#endif#ifdef CONFIG_FB_DEFERRED_IO.fsync =fb_deferred_io_fsync,#endif};

这里有读写控制,打开等操作，我们首先肯定是打开，先看打开：

static intfb_open(struct inode *inode, struct file *file)__acquires(&info->lock)__releases(&info->lock){int fbidx = iminor(inode);struct fb_info *info;int res = 0;if (fbidx >= FB_MAX)return -ENODEV;info = registered_fb[fbidx]; //这里从数组传入一个infoif (!info)request_module("fb%d", fbidx);info = registered_fb[fbidx];if (!info)return -ENODEV;mutex_lock(&info->lock);if (!try_module_get(info->fbops->owner)) {res = -ENODEV;goto out;}file->private_data = info;if (info->fbops->fb_open) {res = info->fbops->fb_open(info,1);  //调用info的打开函数if (res)module_put(info->fbops->owner);}#ifdef CONFIG_FB_DEFERRED_IOif (info->fbdefio)fb_deferred_io_open(info, inode, file);#endifout:mutex_unlock(&info->lock);return res;}

可以知道他首先从registered_fb获取一个info，再调用info的open，再看read：

static ssize_tfb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos){ unsigned long p = *ppos; struct inode *inode = file->f_path.dentry->d_inode; int fbidx = iminor(inode); struct fb_info *info = registered_fb[fbidx];//熟悉吧，我们又看到这个数组了 u32 *buffer, *dst; u32 __iomem *src; int c, i, cnt = 0, err = 0; unsigned long total_size; if (!info || ! info->screen_base)//跟那个数组有关  return -ENODEV; if (info->state != FBINFO_STATE_RUNNING)//跟那个数组有关  return -EPERM; if (info->fbops->fb_read)//如果操作函数集里定义了read函数，就调用，否则就算了  return info->fbops->fb_read(info, buf, count, ppos);  total_size = info->screen_size;//跟那个数组有关 if (total_size == 0)  total_size = info->fix.smem_len;//跟那个数组有关 if (p >= total_size)  return 0; if (count >= total_size)  count = total_size; if (count + p > total_size)  count = total_size - p; buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,//开辟一个buffer    GFP_KERNEL); if (!buffer)  return -ENOMEM; src = (u32 __iomem *) (info->screen_base + p);//显存基地址也在里面 if (info->fbops->fb_sync)  info->fbops->fb_sync(info); while (count) {  c  = (count > PAGE_SIZE) ? PAGE_SIZE : count;  dst = buffer;//目的指针指向一个buffer（我们在上面开辟的）  for (i = c >> 2; i--; )   *dst++ = fb_readl(src++);//从基地址读取数据放进buffer中  if (c & 3) {   u8 *dst8 = (u8 *) dst;   u8 __iomem *src8 = (u8 __iomem *) src;   for (i = c & 3; i--;)    *dst8++ = fb_readb(src8++);   src = (u32 __iomem *) src8;  }  if (copy_to_user(buf, buffer, c))//将buffer中的数据拷贝到用户空间，这样在用户空间调用read函数时就把显存内容读出来了              {   err = -EFAULT;   break;  }  *ppos += c;  buf += c;  cnt += c;  count -= c; } kfree(buffer); return (err) ? err : cnt;}

读函数就是读info里面显存存放的数据，可以知道这个info很重要，那么registered_fb里面放的info，怎么来的？

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;/* check all firmware fbs and kick off if the base addr overlaps */for (i = 0 ; i < FB_MAX; i++) {if (!registered_fb[i])continue;if (registered_fb[i]->flags & FBINFO_MISC_FIRMWARE) {if (fb_do_apertures_overlap(registered_fb[i], fb_info)) {printk(KERN_ERR "fb: conflicting fb hw usage "       "%s vs %s - removing generic driver\n",       fb_info->fix.id,       registered_fb[i]->fix.id);unregister_framebuffer(registered_fb[i]);break;}}}num_registered_fb++;for (i = 0 ; i < FB_MAX; i++)if (!registered_fb[i])break;fb_info->node = i;mutex_init(&fb_info->lock);mutex_init(&fb_info->mm_lock);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;} elsefb_init_device(fb_info);if (fb_info->pixmap.addr == NULL) {fb_info->pixmap.addr = kmalloc(FBPIXMAPSIZE, GFP_KERNEL);if (fb_info->pixmap.addr) {fb_info->pixmap.size = FBPIXMAPSIZE;fb_info->pixmap.buf_align = 1;fb_info->pixmap.scan_align = 1;fb_info->pixmap.access_align = 32;fb_info->pixmap.flags = FB_PIXMAP_DEFAULT;}}fb_info->pixmap.offset = 0;if (!fb_info->pixmap.blit_x)fb_info->pixmap.blit_x = ~(u32)0;if (!fb_info->pixmap.blit_y)fb_info->pixmap.blit_y = ~(u32)0;if (!fb_info->modelist.prev || !fb_info->modelist.next)INIT_LIST_HEAD(&fb_info->modelist);fb_var_to_videomode(&mode, &fb_info->var);fb_add_videomode(&mode, &fb_info->modelist);registered_fb[i] = fb_info;                    //这里放入info到registered_fbevent.info = fb_info;if (!lock_fb_info(fb_info))return -ENODEV;fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);unlock_fb_info(fb_info);return 0;}

可以知道是通过register_framebuffer这个函数放进去的，register_framebuffer又是谁调用的？搜索代码可以知道很多文件都有调用，看S3c2410fb.c可以看到这个在s3c24xxfb_probe里面被调用的，而s3c24xxfb_probe就是s3c24xx这种CPU的LCD驱动程序，这里挂到虚拟总线上了：

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);MODULE_AUTHOR("Arnaud Patard <[e-mail]>, "      "Ben Dooks <[e-mail]>");MODULE_DESCRIPTION("Framebuffer driver for the s3c2410");MODULE_LICENSE("GPL");MODULE_ALIAS("platform:s3c2410-lcd");MODULE_ALIAS("platform:s3c2412-lcd");

所以可以知道最开始看的那个fbmem.c就是LCD驱动的driver端(叫做FrameBuffer驱动)，而这边跟平台有关的S3c2410fb.c等就是LCD驱动的divice端，这个跟之前分析的输入子系统很类似，也是分离的思想，把成熟的软件框架与硬件平台分开，软件框架(driver端)已经帮我们实现了，我们只需要编写divece端，最后把device注册到driver端就可以了。下面看看如何编写device端：

从S3c2410fb.c可以知道我们的LCD驱动就是按要求设置好这个info，然后注册到LCD驱动核心层。这里为了分析思路的清晰，先不考虑虚拟总线，我们自己写一个驱动照着填好这个info，然后设置好跟LCD有关的寄存器就差不多了，然后注册到LCD驱动核心。

1 先把框架写好：

#include <linux/module.h>#include <linux/kernel.h>#include <linux/errno.h>#include <linux/string.h>#include <linux/mm.h>#include <linux/slab.h>#include <linux/delay.h>#include <linux/fb.h>#include <linux/init.h>#include <linux/dma-mapping.h>#include <linux/interrupt.h>#include <linux/workqueue.h>#include <linux/wait.h>#include <linux/platform_device.h>#include <linux/clk.h>#include <asm/io.h>#include <asm/uaccess.h>#include <asm/div64.h>#include <asm/mach/map.h>#include <asm/arch/regs-lcd.h>#include <asm/arch/regs-gpio.h>#include <asm/arch/fb.h>static struct fb_info *s3c_lcd;static int lcd_init(void){/* 1. 分配一个fb_info */s3c_lcd = framebuffer_alloc(0, NULL);/* 2. 设置 *//* 2.1 设置固定的参数 fix *//* 2.2 设置可变的参数 var *//* 2.3 设置操作函数 fbops*//* 2.4 其他的设置 *//* 3. 硬件相关的操作 *//* 3.1 配置GPIO用于LCD *//* 3.2 根据LCD手册设置LCD控制器, 比如VCLK的频率等 *//* 3.3 分配显存(framebuffer), 并把地址告诉LCD控制器 *//* 4. 注册 */register_framebuffer(s3c_lcd);return 0;}static void lcd_exit(void){}module_init(lcd_init);module_exit(lcd_exit);MODULE_LICENSE("GPL");

看下这个info哪些有必要设置：

struct fb_info {int node;int flags;struct mutex lock;/* Lock for open/release/ioctl funcs */struct mutex mm_lock;/* Lock for fb_mmap and smem_* fields */struct fb_var_screeninfo var;/* Current var */struct fb_fix_screeninfo fix;/* Current fix */struct fb_monspecs monspecs;/* Current Monitor specs */struct work_struct queue;/* Framebuffer event queue */struct fb_pixmap pixmap;/* Image hardware mapper */struct fb_pixmap sprite;/* Cursor hardware mapper */struct fb_cmap cmap;/* Current cmap */struct list_head modelist;      /* mode list */struct fb_videomode *mode;/* current mode */#ifdef CONFIG_FB_BACKLIGHT/* assigned backlight device *//* set before framebuffer registration,    remove after unregister */struct backlight_device *bl_dev;/* Backlight level curve */struct mutex bl_curve_mutex;u8 bl_curve[FB_BACKLIGHT_LEVELS];#endif#ifdef CONFIG_FB_DEFERRED_IOstruct delayed_work deferred_work;struct fb_deferred_io *fbdefio;#endifstruct fb_ops *fbops;struct device *device;/* This is the parent */struct device *dev;/* This is this fb device */int class_flag;                    /* private sysfs flags */#ifdef CONFIG_FB_TILEBLITTINGstruct fb_tile_ops *tileops;    /* Tile Blitting */#endifchar __iomem *screen_base;/* Virtual address */unsigned long screen_size;/* Amount of ioremapped VRAM or 0 */ void *pseudo_palette;/* Fake palette of 16 colors */ #define FBINFO_STATE_RUNNING0#define FBINFO_STATE_SUSPENDED1u32 state;/* Hardware state i.e suspend */void *fbcon_par;                /* fbcon use-only private area *//* From here on everything is device dependent */void *par;/* we need the PCI or similiar aperture base/size not   smem_start/size as smem_start may just be an object   allocated inside the aperture so may not actually overlap */resource_size_t aperture_base;resource_size_t aperture_size;};

2 然后来看下info的设置：

#include <linux/module.h>#include <linux/kernel.h>#include <linux/errno.h>#include <linux/string.h>#include <linux/mm.h>#include <linux/slab.h>#include <linux/delay.h>#include <linux/fb.h>#include <linux/init.h>#include <linux/dma-mapping.h>#include <linux/interrupt.h>#include <linux/workqueue.h>#include <linux/wait.h>#include <linux/platform_device.h>#include <linux/clk.h>#include <asm/io.h>#include <asm/uaccess.h>#include <asm/div64.h>#include <asm/mach/map.h>#include <asm/arch/regs-lcd.h>#include <asm/arch/regs-gpio.h>#include <asm/arch/fb.h>//对显存的一些操作函数：static struct fb_ops s3c_lcdfb_ops = {.owner= THIS_MODULE,//.fb_setcolreg= atmel_lcdfb_setcolreg,.fb_fillrect= cfb_fillrect,  //这三个照着写,以后再分析.fb_copyarea= cfb_copyarea,.fb_imageblit= cfb_imageblit,};static struct fb_info *s3c_lcd;static int lcd_init(void){/* 1. 分配一个fb_info */s3c_lcd = framebuffer_alloc(0, NULL);/* 2. 设置 *//* 2.1 设置固定的参数 */strcpy(s3c_lcd->fix.id, "mylcd"); //名称s3c_lcd->fix.smem_len = 240*320*16/8; //显存大小，16bpp所以16位表示一个像素点，240x320的屏幕有240x320个点，再x16就是总位数，再/8就是总字节数s3c_lcd->fix.type     = FB_TYPE_PACKED_PIXELS;s3c_lcd->fix.visual   = FB_VISUAL_TRUECOLOR; /* TFT 真彩色*/s3c_lcd->fix.line_length = 240*2;  //一行的长度，一行240个点，每个点两个字节(16bit)，所以*2/* 2.2 设置可变的参数 */s3c_lcd->var.xres           = 240; //行s3c_lcd->var.yres           = 320; //列s3c_lcd->var.xres_virtual   = 240; //这里设置虚拟屏，我们设置虚拟屏为一样大小s3c_lcd->var.yres_virtual   = 320; s3c_lcd->var.bits_per_pixel = 16;  //每个像素16位/* RGB:565 */s3c_lcd->var.red.offset     = 11;  //16位表示一个像素点的格式是R:G:B分别占5:6:5位s3c_lcd->var.red.length     = 5;s3c_lcd->var.green.offset   = 5;s3c_lcd->var.green.length   = 6;s3c_lcd->var.blue.offset    = 0;s3c_lcd->var.blue.length    = 5;s3c_lcd->var.activate       = FB_ACTIVATE_NOW;/* 2.3 设置操作函数 */s3c_lcd->fbops              = &s3c_lcdfb_ops;    //对显存的操作函数，透明处理等操作/* 2.4 其他的设置 *///s3c_lcd->pseudo_palette =; ////s3c_lcd->screen_base  = ;  /* 显存的虚拟地址 */ s3c_lcd->screen_size   = 240*324*16/8; //和显存大小一样设置/* 3. 硬件相关的操作 *//* 3.1 配置GPIO用于LCD *//* 3.2 根据LCD手册设置LCD控制器, 比如VCLK的频率等 *//* 3.3 分配显存(framebuffer), 并把地址告诉LCD控制器 *///s3c_lcd->fix.smem_start = xxx;  /* 显存的物理地址 *//* 4. 注册 */register_framebuffer(s3c_lcd);return 0;}static void lcd_exit(void){}module_init(lcd_init);module_exit(lcd_exit);MODULE_LICENSE("GPL");

3  info一般设置这些东西，再看些硬件方面的设置：

#include <linux/module.h>#include <linux/kernel.h>#include <linux/errno.h>#include <linux/string.h>#include <linux/mm.h>#include <linux/slab.h>#include <linux/delay.h>#include <linux/fb.h>#include <linux/init.h>#include <linux/dma-mapping.h>#include <linux/interrupt.h>#include <linux/workqueue.h>#include <linux/wait.h>#include <linux/platform_device.h>#include <linux/clk.h>#include <asm/io.h>#include <asm/uaccess.h>#include <asm/div64.h>#include <asm/mach/map.h>#include <asm/arch/regs-lcd.h>#include <asm/arch/regs-gpio.h>#include <asm/arch/fb.h>static int s3c_lcdfb_setcolreg(unsigned int regno, unsigned int red,     unsigned int green, unsigned int blue,     unsigned int transp, struct fb_info *info);struct lcd_regs {unsigned longlcdcon1;unsigned longlcdcon2;unsigned longlcdcon3;unsigned longlcdcon4;unsigned longlcdcon5;    unsigned longlcdsaddr1;    unsigned longlcdsaddr2;    unsigned longlcdsaddr3;    unsigned longredlut;    unsigned longgreenlut;    unsigned longbluelut;    unsigned longreserved[9];    unsigned longdithmode;    unsigned longtpal;    unsigned longlcdintpnd;    unsigned longlcdsrcpnd;    unsigned longlcdintmsk;    unsigned longlpcsel;};static struct fb_ops s3c_lcdfb_ops = {.owner= THIS_MODULE,.fb_setcolreg= s3c_lcdfb_setcolreg,.fb_fillrect= cfb_fillrect,.fb_copyarea= cfb_copyarea,.fb_imageblit= cfb_imageblit,};static struct fb_info *s3c_lcd;static volatile unsigned long *gpbcon;static volatile unsigned long *gpbdat;static volatile unsigned long *gpccon;static volatile unsigned long *gpdcon;static volatile unsigned long *gpgcon;static volatile struct lcd_regs* lcd_regs;static u32 pseudo_palette[16];/* from pxafb.c */static inline unsigned int chan_to_field(unsigned int chan, struct fb_bitfield *bf){chan &= 0xffff;chan >>= 16 - bf->length;return chan << bf->offset;}static int s3c_lcdfb_setcolreg(unsigned int regno, unsigned int red,     unsigned int green, unsigned int blue,     unsigned int transp, struct fb_info *info){unsigned int val;if (regno > 16)return 1;/* 用red,green,blue三原色构造出val */val  = chan_to_field(red,&info->var.red);val |= chan_to_field(green, &info->var.green);val |= chan_to_field(blue,&info->var.blue);//((u32 *)(info->pseudo_palette))[regno] = val;pseudo_palette[regno] = val;return 0;}static int lcd_init(void){/* 1. 分配一个fb_info */s3c_lcd = framebuffer_alloc(0, NULL);/* 2. 设置 *//* 2.1 设置固定的参数 */strcpy(s3c_lcd->fix.id, "mylcd");s3c_lcd->fix.smem_len = 240*320*16/8;s3c_lcd->fix.type     = FB_TYPE_PACKED_PIXELS;s3c_lcd->fix.visual   = FB_VISUAL_TRUECOLOR; /* TFT */s3c_lcd->fix.line_length = 240*2;/* 2.2 设置可变的参数 */s3c_lcd->var.xres           = 240;s3c_lcd->var.yres           = 320;s3c_lcd->var.xres_virtual   = 240;s3c_lcd->var.yres_virtual   = 320;s3c_lcd->var.bits_per_pixel = 16;/* RGB:565 */s3c_lcd->var.red.offset     = 11;s3c_lcd->var.red.length     = 5;s3c_lcd->var.green.offset   = 5;s3c_lcd->var.green.length   = 6;s3c_lcd->var.blue.offset    = 0;s3c_lcd->var.blue.length    = 5;s3c_lcd->var.activate       = FB_ACTIVATE_NOW;/* 2.3 设置操作函数 */s3c_lcd->fbops              = &s3c_lcdfb_ops;/* 2.4 其他的设置 */s3c_lcd->pseudo_palette = pseudo_palette;//s3c_lcd->screen_base  = ;  /* 显存的虚拟地址 */ s3c_lcd->screen_size   = 240*324*16/8;/* 3. 硬件相关的操作 *//* 3.1 配置GPIO用于LCD */gpbcon = ioremap(0x56000010, 8);gpbdat = gpbcon+1;gpccon = ioremap(0x56000020, 4);gpdcon = ioremap(0x56000030, 4);gpgcon = ioremap(0x56000060, 4);    *gpccon  = 0xaaaaaaaa;   /* GPIO管脚用于VD[7:0],LCDVF[2:0],VM,VFRAME,VLINE,VCLK,LEND */*gpdcon  = 0xaaaaaaaa;   /* GPIO管脚用于VD[23:8] */*gpbcon &= ~(3);  /* GPB0设置为输出引脚 */*gpbcon |= 1;*gpbdat &= ~1;     /* 输出低电平 */*gpgcon |= (3<<8); /* GPG4用作LCD_PWREN *//* 3.2 根据LCD手册设置LCD控制器, 比如VCLK的频率等 */lcd_regs = ioremap(0x4D000000, sizeof(struct lcd_regs));/* bit[17:8]: VCLK = HCLK / [(CLKVAL+1) x 2], LCD手册P14 *            10MHz(100ns) = 100MHz / [(CLKVAL+1) x 2] *            CLKVAL = 4 * bit[6:5]: 0b11, TFT LCD * bit[4:1]: 0b1100, 16 bpp for TFT * bit[0]  : 0 = Disable the video output and the LCD control signal. */lcd_regs->lcdcon1  = (4<<8) | (3<<5) | (0x0c<<1);/* 垂直方向的时间参数 * bit[31:24]: VBPD, VSYNC之后再过多长时间才能发出第1行数据 *             LCD手册 T0-T2-T1=4 *             VBPD=3 * bit[23:14]: 多少行, 320, 所以LINEVAL=320-1=319 * bit[13:6] : VFPD, 发出最后一行数据之后，再过多长时间才发出VSYNC *             LCD手册T2-T5=322-320=2, 所以VFPD=2-1=1 * bit[5:0]  : VSPW, VSYNC信号的脉冲宽度, LCD手册T1=1, 所以VSPW=1-1=0 */lcd_regs->lcdcon2  = (3<<24) | (319<<14) | (1<<6) | (0<<0);/* 水平方向的时间参数 * bit[25:19]: HBPD, VSYNC之后再过多长时间才能发出第1行数据 *             LCD手册 T6-T7-T8=17 *             HBPD=16 * bit[18:8]: 多少列, 240, 所以HOZVAL=240-1=239 * bit[7:0] : HFPD, 发出最后一行里最后一个象素数据之后，再过多长时间才发出HSYNC *             LCD手册T8-T11=251-240=11, 所以HFPD=11-1=10 */lcd_regs->lcdcon3 = (16<<19) | (239<<8) | (10<<0);/* 水平方向的同步信号 * bit[7:0]: HSPW, HSYNC信号的脉冲宽度, LCD手册T7=5, 所以HSPW=5-1=4 */lcd_regs->lcdcon4 = 4;/* 信号的极性  * bit[11]: 1=565 format * bit[10]: 0 = The video data is fetched at VCLK falling edge * bit[9] : 1 = HSYNC信号要反转,即低电平有效  * bit[8] : 1 = VSYNC信号要反转,即低电平有效  * bit[6] : 0 = VDEN不用反转 * bit[3] : 0 = PWREN输出0 * bit[1] : 0 = BSWP * bit[0] : 1 = HWSWP 2440手册P413 */lcd_regs->lcdcon5 = (1<<11) | (0<<10) | (1<<9) | (1<<8) | (1<<0);/* 3.3 分配显存(framebuffer), 并把地址告诉LCD控制器 */s3c_lcd->screen_base = dma_alloc_writecombine(NULL, s3c_lcd->fix.smem_len, &s3c_lcd->fix.smem_start, GFP_KERNEL);lcd_regs->lcdsaddr1  = (s3c_lcd->fix.smem_start >> 1) & ~(3<<30);lcd_regs->lcdsaddr2  = ((s3c_lcd->fix.smem_start + s3c_lcd->fix.smem_len) >> 1) & 0x1fffff;lcd_regs->lcdsaddr3  = (240*16/16);  /* 一行的长度(单位: 2字节) *///s3c_lcd->fix.smem_start = xxx;  /* 显存的物理地址 *//* 启动LCD */lcd_regs->lcdcon1 |= (1<<0); /* 使能LCD控制器 */lcd_regs->lcdcon5 |= (1<<3); /* 使能LCD本身 */*gpbdat |= 1;     /* 输出高电平, 使能背光 *//* 4. 注册 */register_framebuffer(s3c_lcd);return 0;}static void lcd_exit(void){unregister_framebuffer(s3c_lcd);lcd_regs->lcdcon1 &= ~(1<<0); /* 关闭LCD本身 */*gpbdat &= ~1;     /* 关闭背光 */dma_free_writecombine(NULL, s3c_lcd->fix.smem_len, s3c_lcd->screen_base, s3c_lcd->fix.smem_start);iounmap(lcd_regs);iounmap(gpbcon);iounmap(gpccon);iounmap(gpdcon);iounmap(gpgcon);framebuffer_release(s3c_lcd);}module_init(lcd_init);module_exit(lcd_exit);MODULE_LICENSE("GPL");