LCD驱动分析之s3c2410fb.c

 

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#ifdef CONFIG_PM
#include
#endif

#include "s3c2410fb.h"

#ifdef CONFIG_FB_S3C2410_DEBUG
static int debug = 1;
#else
static int debug = 0;
#endif

#define dprintk(msg...) if (debug) { printk(KERN_DEBUG "s3c2410fb: " msg); }

 

static int is_s3c2412(struct s3c2410fb_info *fbi)
{
 return (fbi->drv_type == DRV_S3C2412);//CPU类型
}

 //设置LCD 控制器的Address 1，Address 2，Address 3。
static void s3c2410fb_set_lcdaddr(struct fb_info *info)
{
 unsigned long saddr1, saddr2, saddr3;
 struct s3c2410fb_info *fbi = info->par;
 void __iomem *regs = fbi->io;

 saddr1  = info->fix.smem_start >> 1;//半字
 saddr2  = info->fix.smem_start;
 saddr2 += info->fix.line_length * info->var.yres;//OFFSIZE为零
 saddr2 >>= 1;
//fix.line_length在函数s3c2410fb_set_par中初始化，以字节为单位
 saddr3 = S3C2410_OFFSIZE(0) |//OFFSIZE为零
   S3C2410_PAGEWIDTH((info->fix.line_length / 2) & 0x3ff);//虚拟屏宽

 dprintk("LCDSADDR1 = 0x%08lx\n", saddr1);
 dprintk("LCDSADDR2 = 0x%08lx\n", saddr2);
 dprintk("LCDSADDR3 = 0x%08lx\n", saddr3);

 writel(saddr1, regs + S3C2410_LCDSADDR1);
 writel(saddr2, regs + S3C2410_LCDSADDR2);
 writel(saddr3, regs + S3C2410_LCDSADDR3);
}

static unsigned int s3c2410fb_calc_pixclk(struct s3c2410fb_info *fbi,
       unsigned long pixclk)
{
 unsigned long clk = clk_get_rate(fbi->clk);
 unsigned long long div;

 
//pixclk为像素时钟，即画一个像素需要的皮秒数。1皮秒为10^-12秒
//产生时间pixclk的时钟应该是1/pixclk即clk分频后的值即1/pixclk=clk/div.
 div = (unsigned long long)clk * pixclk;
 div >>= 12;   
 do_div(div, 625 * 625UL * 625); //将皮秒化为秒

 dprintk("pixclk %ld, divisor is %ld\n", pixclk, (long)div);
 return div;
}

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;//移植时需要注意的重要结构
 struct s3c2410fb_display *display = NULL;
 struct s3c2410fb_display *default_display = mach_info->displays +
          mach_info->default_display;
 int type = default_display->type;
 unsigned i;

 dprintk("check_var(var=%p, info=%p)\n", var, info);

 
 //找出一个匹配的display
 if (var->yres == default_display->yres &&
     var->xres == default_display->xres &&
     var->bits_per_pixel == default_display->bpp)
  display = default_display;
 else
  for (i = 0; i < mach_info->num_displays; i++)
   if (type == mach_info->displays[i].type &&
       var->yres == mach_info->displays[i].yres &&
       var->xres == mach_info->displays[i].xres &&
       var->bits_per_pixel == mach_info->displays[i].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;
 }
//根据找出的display初始化var结构成员
 
 var->xres_virtual = display->xres;//虚拟屏对应着同样大小的实际屏，
 var->yres_virtual = display->yres;//虚拟屏的显存即为实际屏的显存
 var->height = display->height;
 var->width = display->width;

 
 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;

 fbi->regs.lcdcon5 = display->lcdcon5;
 
 fbi->regs.lcdcon1 = display->type;

 var->transp.offset = 0;
 var->transp.length = 0;
 
 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) {
   
   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:
  
  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) {
   
   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 {
   
   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:
  
  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;
}

//根据var的值设定液晶面板的宽长，每像素的位数等值
static void s3c2410fb_calculate_stn_lcd_regs(const struct fb_info *info,
          struct s3c2410fb_hw *regs)
{
 const struct s3c2410fb_info *fbi = info->par;
 const struct fb_var_screeninfo *var = &info->var;
 int type = regs->lcdcon1 & ~S3C2410_LCDCON1_TFT;
 int hs = var->xres >> 2;
 unsigned wdly = (var->left_margin >> 4) - 1;
 unsigned wlh = (var->hsync_len >> 4) - 1;

 if (type != S3C2410_LCDCON1_STN4)
  hs >>= 1;

 switch (var->bits_per_pixel) {
 case 1:
  regs->lcdcon1 |= S3C2410_LCDCON1_STN1BPP;
  break;
 case 2:
  regs->lcdcon1 |= S3C2410_LCDCON1_STN2GREY;
  break;
 case 4:
  regs->lcdcon1 |= S3C2410_LCDCON1_STN4GREY;
  break;
 case 8:
  regs->lcdcon1 |= S3C2410_LCDCON1_STN8BPP;
  hs *= 3;
  break;
 case 12:
  regs->lcdcon1 |= S3C2410_LCDCON1_STN12BPP;
  hs *= 3;
  break;

 default:
  
  dev_err(fbi->dev, "invalid bpp %d\n",
   var->bits_per_pixel);
 }
 
 dprintk("setting horz: lft=%d, rt=%d, sync=%d\n",
  var->left_margin, var->right_margin, var->hsync_len);

 regs->lcdcon2 = S3C2410_LCDCON2_LINeval_r(var->yres - 1);

 if (wdly > 3)
  wdly = 3;

 if (wlh > 3)
  wlh = 3;

 regs->lcdcon3 = S3C2410_LCDCON3_WDLY(wdly) |
   S3C2410_LCDCON3_LINEBLANK(var->right_margin / 8) |
   S3C2410_LCDCON3_HOZVAL(hs - 1);

 regs->lcdcon4 = S3C2410_LCDCON4_WLH(wlh);
}

//根据var的值设定液晶面板的宽长，每像素的位数等值
static void s3c2410fb_calculate_tft_lcd_regs(const struct fb_info *info,
          struct s3c2410fb_hw *regs)
{
 const struct s3c2410fb_info *fbi = info->par;
 const struct fb_var_screeninfo *var = &info->var;

 switch (var->bits_per_pixel) {
 case 1:
  regs->lcdcon1 |= S3C2410_LCDCON1_TFT1BPP;
  break;
 case 2:
  regs->lcdcon1 |= S3C2410_LCDCON1_TFT2BPP;
  break;
 case 4:
  regs->lcdcon1 |= S3C2410_LCDCON1_TFT4BPP;
  break;
 case 8:
  regs->lcdcon1 |= S3C2410_LCDCON1_TFT8BPP;
  regs->lcdcon5 |= S3C2410_LCDCON5_BSWP |
     S3C2410_LCDCON5_FRM565;
  regs->lcdcon5 &= ~S3C2410_LCDCON5_HWSWP;
  break;
 case 16:
  regs->lcdcon1 |= S3C2410_LCDCON1_TFT16BPP;
  regs->lcdcon5 &= ~S3C2410_LCDCON5_BSWP;
  regs->lcdcon5 |= S3C2410_LCDCON5_HWSWP;
  break;
 case 32:
  regs->lcdcon1 |= S3C2410_LCDCON1_TFT24BPP;
  regs->lcdcon5 &= ~(S3C2410_LCDCON5_BSWP |
       S3C2410_LCDCON5_HWSWP |
       S3C2410_LCDCON5_BPP24BL);
  break;
 default:
  
  dev_err(fbi->dev, "invalid bpp %d\n",
   var->bits_per_pixel);
 }
 
 dprintk("setting vert: up=%d, low=%d, sync=%d\n",
  var->upper_margin, var->lower_margin, var->vsync_len);

 dprintk("setting horz: lft=%d, rt=%d, sync=%d\n",
  var->left_margin, var->right_margin, var->hsync_len);

 regs->lcdcon2 = S3C2410_LCDCON2_LINeval_r(var->yres - 1) |//面板的实际垂直高度
   S3C2410_LCDCON2_VBPD(var->upper_margin - 1) |
   S3C2410_LCDCON2_VFPD(var->lower_margin - 1) |
   S3C2410_LCDCON2_VSPW(var->vsync_len - 1);

 regs->lcdcon3 = S3C2410_LCDCON3_HBPD(var->right_margin - 1) |
   S3C2410_LCDCON3_HFPD(var->left_margin - 1) |
   S3C2410_LCDCON3_HOZVAL(var->xres - 1);//面板水平宽度

 regs->lcdcon4 = S3C2410_LCDCON4_HSPW(var->hsync_len - 1);
}

//将设定好的各参数值写入相应寄存器，5个LCDCON和3个LCDSADDR
static void s3c2410fb_activate_var(struct fb_info *info)
{
 struct s3c2410fb_info *fbi = info->par;
 void __iomem *regs = fbi->io;
 int type = fbi->regs.lcdcon1 & S3C2410_LCDCON1_TFT;
 struct s3c2410fb_mach_info *mach_info = fbi->dev->platform_data;
 struct s3c2410fb_display *default_display = mach_info->displays +
          mach_info->default_display;
 struct fb_var_screeninfo *var = &info->var;
 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) {
  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;
 }

// fbi->regs.lcdcon1 |=  S3C2410_LCDCON1_CLKVAL(clkdiv);
 fbi->regs.lcdcon1 |=  S3C2410_LCDCON1_CLKVAL(default_display->setclkval);

 

 dprintk("new register set:\n");
 dprintk("lcdcon[1] = 0x%08lx\n", fbi->regs.lcdcon1);
 dprintk("lcdcon[2] = 0x%08lx\n", fbi->regs.lcdcon2);
 dprintk("lcdcon[3] = 0x%08lx\n", fbi->regs.lcdcon3);
 dprintk("lcdcon[4] = 0x%08lx\n", fbi->regs.lcdcon4);
 dprintk("lcdcon[5] = 0x%08lx\n", fbi->regs.lcdcon5);

 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);

 
 s3c2410fb_set_lcdaddr(info);

 fbi->regs.lcdcon1 |= S3C2410_LCDCON1_ENVID,
 writel(fbi->regs.lcdcon1, regs + S3C2410_LCDCON1);
}

//设定fix的几个结构成员和激活LCD控制寄存器
static int s3c2410fb_set_par(struct fb_info *info)
{
 struct fb_var_screeninfo *var = &info->var;

 switch (var->bits_per_pixel) {
 case 32:
 case 16:
 case 12:
  info->fix.visual = FB_VISUAL_TRUECOLOR;
  break;
 case 1:
  info->fix.visual = FB_VISUAL_MONO01;
  break;
 default:
  info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
  break;
 }

 info->fix.line_length = (var->xres_virtual * var->bits_per_pixel) / 8;

 

 s3c2410fb_activate_var(info);
 return 0;
}

static void schedule_palette_update(struct s3c2410fb_info *fbi,
        unsigned int regno, unsigned int val)
{
 unsigned long flags;
 unsigned long irqen;
 void __iomem *irq_base = fbi->irq_base;

 local_irq_save(flags);

 fbi->palette_buffer[regno] = val;

 if (!fbi->palette_ready) {
  fbi->palette_ready = 1;

  
  irqen = readl(irq_base + S3C24XX_LCDINTMSK);
  irqen &= ~S3C2410_LCDINT_FRSYNC;
  writel(irqen, irq_base + S3C24XX_LCDINTMSK);//使能帧同步中断
 }

 local_irq_restore(flags);
}

static inline unsigned int chan_to_field(unsigned int chan,
      struct fb_bitfield *bf)
{
 //chan是16位red，green，blue。如果bpp为565， green的length为6，offset为5。
 chan &= 0xffff;
 chan >>= 16 - bf->length;
 return chan << bf->offset;
}

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;

 
//info->fix.visual的值在函数s3c2410fb_set_par中设置
 switch (info->fix.visual) {
 case FB_VISUAL_TRUECOLOR://真彩
  
//在函数s3c24xxfb_probe中初始化fbinfo->pseudo_palette = &info->pseudo_pal;
  if (regno < 16) {//即为真彩就有64K以上的颜色值，而又有regno < 16的限制，不明白为什么？？？？？？？
   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[regno] = val;
  }
  break;
//565模式bpp为16而在函数s3c2410fb_set_par中bpp为16的被设为真彩，
//而此处伪彩中却出现了565模式，不明白为什么？？？？？？？？？
 case FB_VISUAL_PSEUDOCOLOR://伪彩
  if (regno < 256) {
   

   val  = (red   >>  0) & 0xf800;
   val |= (green >>  5) & 0x07e0;
   val |= (blue  >> 11) & 0x001f;
//既然将val已写入了颜色寄存器为什么还调用schedule_palette_update(fbi, regno, val);
//在中断处理函数中再次写入颜色寄存器？？？？？？？？？
   writel(val, regs + S3C2410_TFTPAL(regno));
   schedule_palette_update(fbi, regno, val);
  }

  break;

 default:
  return 1; 
 }

 return 0;
}

//LCD的开启和关闭。
static void s3c2410fb_lcd_enable(struct s3c2410fb_info *fbi, int enable)
{
 unsigned long flags;

 local_irq_save(flags);

 if (enable)
  fbi->regs.lcdcon1 |= S3C2410_LCDCON1_ENVID;
 else
  fbi->regs.lcdcon1 &= ~S3C2410_LCDCON1_ENVID;

 writel(fbi->regs.lcdcon1, fbi->io + S3C2410_LCDCON1);

 local_irq_restore(flags);
}

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) {
  s3c2410fb_lcd_enable(fbi, 0);
 } else {
  s3c2410fb_lcd_enable(fbi, 1);
 }

 if (blank_mode == FB_BLANK_UNBLANK)
  writel(0x0, tpal_reg);//临时调色板寄存器干甚用的？？？？？？？？？
 else {
  dprintk("setting TPAL to output 0x000000\n");
  writel(S3C2410_TPAL_EN, tpal_reg);
 }

 return 0;
}

static int s3c2410fb_debug_show(struct device *dev,
    struct device_attribute *attr, char *buf)
{
 return snprintf(buf, PAGE_SIZE, "%s\n", debug ? "on" : "off");
}

static int s3c2410fb_debug_store(struct device *dev,
     struct device_attribute *attr,
     const char *buf, size_t len)
{
 if (len < 1)
  return -EINVAL;

 if (strnicmp(buf, "on", 2) == 0 ||
     strnicmp(buf, "1", 1) == 0) {
  debug = 1;
  printk(KERN_DEBUG "s3c2410fb: Debug On");
 } else if (strnicmp(buf, "off", 3) == 0 ||
     strnicmp(buf, "0", 1) == 0) {
  debug = 0;
  printk(KERN_DEBUG "s3c2410fb: Debug Off");
 } else {
  return -EINVAL;
 }

 return len;
}
//设备属性
static DEVICE_ATTR(debug, 0666, s3c2410fb_debug_show, s3c2410fb_debug_store);

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,
};

static int __init s3c2410fb_map_video_memory(struct fb_info *info)
{
 struct s3c2410fb_info *fbi = info->par;
 dma_addr_t map_dma;
 unsigned map_size = PAGE_ALIGN(info->fix.smem_len);

 dprintk("map_video_memory(fbi=%p) map_size %u\n", fbi, map_size);

 info->screen_base = dma_alloc_writecombine(fbi->dev, map_size,
         &map_dma, GFP_KERNEL);
//info->screen_base为虚拟地址，map_dma为物理地址。
 if (info->screen_base) {
  
  dprintk("map_video_memory: clear %p:%08x\n",
   info->screen_base, map_size);
  memset(info->screen_base, 0x00, map_size);
//将map_dma作为fb缓存的开始地址，说明该驱动不支持滚屏显示，如果支持滚屏显示应该分配一段内存
//将首地址给info->fix.mmio_start，info->fix.smem_start 的值应是所分配的内存中的某个值。
  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);
 }

 return info->screen_base ? 0 : -ENOMEM;
}
//内存释放
static inline void s3c2410fb_unmap_video_memory(struct fb_info *info)
{
 struct s3c2410fb_info *fbi = info->par;

 dma_free_writecombine(fbi->dev, PAGE_ALIGN(info->fix.smem_len),
         info->screen_base, info->fix.smem_start);
}
//将对io端口寄存器的配置值写入相应寄存器
static inline void modify_gpio(void __iomem *reg,
          unsigned long set, unsigned long mask)
{
 unsigned long tmp;

 tmp = readl(reg) & ~mask;
 writel(tmp | set, reg);
}

//管脚配置
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;
 void __iomem *regs = fbi->io;
 void __iomem *tpal;
 void __iomem *lpcsel;

 if (is_s3c2412(fbi)) {
  tpal = regs + S3C2412_TPAL;
  lpcsel = regs + S3C2412_TCONSEL;
 } else {
  tpal = regs + S3C2410_TPAL;
  lpcsel = regs + S3C2410_LPCSEL;
 }

 

 local_irq_save(flags);

 

 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);

 local_irq_restore(flags);

 dprintk("LPCSEL    = 0x%08lx\n", mach_info->lpcsel);
 writel(mach_info->lpcsel, lpcsel);

 dprintk("replacing TPAL %08x\n", readl(tpal));

 
 writel(0x00, tpal);

 return 0;
}
//把设定的颜色值写入颜色寄存器
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[i];
  if (ent == PALETTE_BUFF_CLEAR)
   continue;

  writel(ent, regs + S3C2410_TFTPAL(i));

  
//检测是否成功写入
  if (readw(regs + S3C2410_TFTPAL(i)) == ent)
   fbi->palette_buffer[i] = PALETTE_BUFF_CLEAR;//如果写入成功则清零
  else
   fbi->palette_ready = 1;   //只要该标志为1中断函数中就会调用这个函数
 }
}
//每帧结束中断处理函数
static irqreturn_t s3c2410fb_irq(int irq, void *dev_id)
{
 struct s3c2410fb_info *fbi = dev_id;
 void __iomem *irq_base = fbi->irq_base;
 unsigned long lcdirq = readl(irq_base + S3C24XX_LCDINTPND);

 if (lcdirq & S3C2410_LCDINT_FRSYNC) {
  if (fbi->palette_ready)//如果为帧结束中断且标志置一，调用以下函数
   s3c2410fb_write_palette(fbi);
//清零中断标志位
  writel(S3C2410_LCDINT_FRSYNC, irq_base + S3C24XX_LCDINTPND);
  writel(S3C2410_LCDINT_FRSYNC, irq_base + S3C24XX_LCDSRCPND);
 }

 return IRQ_HANDLED;
}

static char driver_name[] = "s3c2410fb";

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;
//mach_info该结构体在文件mach-tq2440.c中定义，移植时重点关注的结构体
 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;
 }

 display = mach_info->displays + mach_info->default_display;
//获取中断号
 irq = platform_get_irq(pdev, 0);
 if (irq < 0) {
  dev_err(&pdev->dev, "no irq for device\n");
  return -ENOENT;
 }
//为结构体fb_info和 s3c2410fb_info分配内存并让指针info->par指向s3c2410fb_info
 fbinfo = framebuffer_alloc(sizeof(struct s3c2410fb_info), &pdev->dev);
 if (!fbinfo)
  return -ENOMEM;
//将结构体fbinfo设为pdev的drvdata
 platform_set_drvdata(pdev, fbinfo);

 info = fbinfo->par;
 info->dev = &pdev->dev;
 info->drv_type = drv_type;//cpu类型
//获取硬件资源
 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;
 info->mem = request_mem_region(res->start, size, pdev->name);//申请一段内存
 if (info->mem == NULL) {
  dev_err(&pdev->dev, "failed to get memory region\n");
  ret = -ENOENT;
  goto dealloc_fb;
 }
//io映射
 info->io = ioremap(res->start, size);
 if (info->io == NULL) {
  dev_err(&pdev->dev, "ioremap() of registers failed\n");
  ret = -ENXIO;
  goto release_mem;
 }
//初始化基地址
 info->irq_base = info->io + ((drv_type == DRV_S3C2412) ? S3C2412_LCDINTBASE : S3C2410_LCDINTBASE);

 dprintk("devinit\n");

 strcpy(fbinfo->fix.id, driver_name);

 
 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;

 fbinfo->fbops      = &s3c2410fb_ops;
 fbinfo->flags      = FBINFO_FLAG_DEFAULT;
 fbinfo->pseudo_palette      = &info->pseudo_pal;

 for (i = 0; i < 256; i++)//清零调色板
  info->palette_buffer[i] = PALETTE_BUFF_CLEAR;
//申请中断并关联中断函数
 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;
 }
//获取时钟
 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;
 }
//使能时钟
 clk_enable(info->clk);
 dprintk("got and enabled clock\n");

 msleep(1);//待时钟稳定

 
 for (i = 0; i < mach_info->num_displays; i++) {
  unsigned long smem_len = mach_info->displays[i].xres;

  smem_len *= mach_info->displays[i].yres;
  smem_len *= mach_info->displays[i].bpp;
  smem_len >>= 3;
  if (fbinfo->fix.smem_len < smem_len)
   fbinfo->fix.smem_len = smem_len;
 }

 
 ret = s3c2410fb_map_video_memory(fbinfo);//获取显存
 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;

 s3c2410fb_init_registers(fbinfo);//配置端口

 s3c2410fb_check_var(&fbinfo->var, fbinfo);//初始化fbinfo->var的各成员值
//以下函数主要是创建设备fb_info->dev即为用户空间的操作节点
 ret = register_framebuffer(fbinfo);
 if (ret < 0) {
  printk(KERN_ERR "Failed to register framebuffer device: %d\n",
   ret);
  goto free_video_memory;
 }

 //创建文件属性
 ret = device_create_file(&pdev->dev, &dev_attr_debug);
 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;
}

static int __init s3c2410fb_probe(struct platform_device *pdev)
{
 return s3c24xxfb_probe(pdev, DRV_S3C2410);
}

static int __init s3c2412fb_probe(struct platform_device *pdev)
{
 return s3c24xxfb_probe(pdev, DRV_S3C2412);
}

static int s3c2410fb_remove(struct platform_device *pdev)
{
 struct fb_info *fbinfo = platform_get_drvdata(pdev);
 struct s3c2410fb_info *info = fbinfo->par;
 int irq;

 unregister_framebuffer(fbinfo);

 s3c2410fb_lcd_enable(info, 0);
 msleep(1);

 s3c2410fb_unmap_video_memory(fbinfo);

 if (info->clk) {
  clk_disable(info->clk);
  clk_put(info->clk);
  info->clk = NULL;
 }

 irq = platform_get_irq(pdev, 0);
 free_irq(irq, info);

 iounmap(info->io);

 release_resource(info->mem);
 kfree(info->mem);

 platform_set_drvdata(pdev, NULL);
 framebuffer_release(fbinfo);

 return 0;
}

#ifdef CONFIG_PM

static int s3c2410fb_suspend(struct platform_device *dev, pm_message_t state)
{
 struct fb_info    *fbinfo = platform_get_drvdata(dev);
 struct s3c2410fb_info *info = fbinfo->par;

 s3c2410fb_lcd_enable(info, 0);

 

 msleep(1);
 clk_disable(info->clk);

 return 0;
}

static int s3c2410fb_resume(struct platform_device *dev)
{
 struct fb_info    *fbinfo = platform_get_drvdata(dev);
 struct s3c2410fb_info *info = fbinfo->par;

 clk_enable(info->clk);
 msleep(1);

 s3c2410fb_init_registers(fbinfo);

 
 s3c2410fb_activate_var(fbinfo);
 s3c2410fb_blank(FB_BLANK_UNBLANK, fbinfo);

 return 0;
}

#else
#define s3c2410fb_suspend NULL
#define s3c2410fb_resume  NULL
#endif

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,
 },
};

static struct platform_driver s3c2412fb_driver = {
 .probe  = s3c2412fb_probe,
 .remove  = s3c2410fb_remove,
 .suspend = s3c2410fb_suspend,
 .resume  = s3c2410fb_resume,
 .driver  = {
  .name = "s3c2412-lcd",
  .owner = THIS_MODULE,
 },
};

int __init s3c2410fb_init(void)
{//注册驱动
 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 <>, "
       "Ben Dooks <>");
MODULE_DESCRIPTION("Framebuffer driver for the s3c2410");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:s3c2410-lcd");
MODULE_ALIAS("platform:s3c2412-lcd");