LCD及FrameBuffer驱动（四）————FrameBuffer驱动实现实例

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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 long   lcdcon1;
    unsigned long   lcdcon2;
    unsigned long   lcdcon3;
    unsigned long   lcdcon4;
    unsigned long   lcdcon5;
    unsigned long   lcdsaddr1;
    unsigned long   lcdsaddr2;
    unsigned long   lcdsaddr3;
    unsigned long   redlut;
    unsigned long   greenlut;
    unsigned long   bluelut;
    unsigned long   reserved[9];
    unsigned long   dithmode;
    unsigned long   tpal;
    unsigned long   lcdintpnd;
    unsigned long   lcdsrcpnd;
    unsigned long   lcdintmsk;
    unsigned long   lpcsel;
};

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 = 320*240*16/8;        /* TQ2440的LCD位宽是24,但是2440里会分配4字节即32位(浪费1字节) */
    s3c_lcd->fix.type     = FB_TYPE_PACKED_PIXELS;
    s3c_lcd->fix.visual   = FB_VISUAL_TRUECOLOR; /* TFT */
    s3c_lcd->fix.line_length = 320*2;

    /* 2.2 设置可变的参数 */
    s3c_lcd->var.xres           = 320;
    s3c_lcd->var.yres           = 240;
    s3c_lcd->var.xres_virtual   = 320;
    s3c_lcd->var.yres_virtual   = 240;
    s3c_lcd->var.xoffset        =0;
    s3c_lcd->var.yoffset        =0;
    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   =320*240*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));

    /* 
     * TQ2440 4.3英寸LCD手册为WXCAT43-TG6#001_V1.0.pdf第22、23页
     * 
     * LCD手册和2440手册"Figure 15-6. TFT LCD Timing Example"一对比就知道参数含义了
     */

    /* bit[17:8]: VCLK = HCLK / [(CLKVAL+1) x 2], LCD手册P22 (Dclk=9MHz~15MHz)
     *            10MHz(100ns) = 100MHz / [(CLKVAL+1) x 2]
     *            CLKVAL = 4
     * bit[6:5]: 0b11, TFT LCD
     * bit[4:1]: 0b1101, 24 bpp for TFT
     * bit[0]  : 0 = Disable the video output and the LCD control signal.
     */
    lcd_regs->lcdcon1  = (7<<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 tvb=2
     *             VBPD=1
     * bit[23:14]: 多少行, 272, 所以LINEVAL=272-1=271
     * 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tvf=2, 所以VFPD=2-1=1
     * bit[5:0]  : VSPW, VSYNC信号的脉冲宽度, LCD手册tvp=10, 所以VSPW=10-1=9
     */
    lcd_regs->lcdcon2  = (4<<24) | (239<<14) | (4<<6) | (4<<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 thb=2
     *             HBPD=1
     * bit[18:8]: 多少列, 480, 所以HOZVAL=480-1=479
     * 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thf=2, 所以HFPD=2-1=1
     */
    //lcd_regs->lcdcon3 = (13<<19) | (319<<8) | (4<<0);
    //lcd_regs->lcdcon3 = (1<<19) | (319<<8) | (0<<0);
    lcd_regs->lcdcon3 = (0<<19) | (319<<8) | (4<<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Thp=41, 所以HSPW=41-1=40
     */ 
    lcd_regs->lcdcon4 = (13<<8)|(18);

    /* 信号的极性 
     * bit[11]: 1=565 format, 对于24bpp这个不用设
     * 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
     *
     * BSWP = 0, HWSWP = 0, BPP24BL = 0 : 当bpp=24时,2440会给每一个象素分配32位即4字节,哪一个字节是不使用的? 看2440手册P412
         * bit[12]: 0, LSB valid, 即最高字节不使用
     * bit[1] : 0 = BSWP
     * bit[0] : 0 = HWSWP
     */
    lcd_regs->lcdcon5 = (1<<11)|(0<<10) | (1<<9) | (1<<8) | (0<<12) | (0<<1) | (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  =(320*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: LCD_PWREN */
//  *gpbdat |= 1;     /* 输出高电平, 使能背光, TQ2440的背光电路也是通过LCD_PWREN来控制的 */

    /* 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控制器 */
    lcd_regs->lcdcon1 &= ~(1<<3); /* 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");