帧缓冲驱动程序设计

显存----

帧缓冲----显示缓存

FrameBuffer从本质上讲是图形设备的硬件抽象。对开发者而言，FrameBuffer是一块显示缓存，往显示缓存中写入特定格式的数据就意味着向屏幕输出内容。通过不断的向frame buffer中写入数据，显示控制器就自动的从frame buffer中取数据并显示出来。

帧缓冲设备对应的设备文件为/dev/fb*，如果系统有多个显示卡，linux下还可支持多个帧缓冲设备，最多可达32个，分别为/dev/fb0到/dev/fb31，而/dev/fb0则为当前缺省的帧缓冲设备，通常指向/dev/fb0。帧缓冲设备为标准字符设备，主设备号为29，次设备号则从0到31.

访问帧缓冲设备---实例演示

1清除LCD

dd if=/dev/zero/fb0 bs=240 count=320   bs-- block size 以块的方式，每个240字节。

2运行应用程序，画图

./lcd

3清除lcd

dd if=/dev/zero of=/dev/fb0 bs=240 count=320

4显示图片

cat 7.bmp>/dev/fb0

-------------------系统架构-----------------------

设备描述

linux内核使用struct fb_info来描述帧缓冲设备。

struct fb_info

{

.................................................................................

struct fb_var_screeninfo var;可变参数

struct fb_fix_screeninfo fix; 固定参数

.................................................................................

struct fb_ops *fbops;帧缓冲操作

....................................................................................

};

可变参数

struct fb_var_screeninfo var记录了用户可以修改的显示参数，包括屏幕分辨率等。

struct fb_var_screeninfo {
    __u32 xres;            /* visible resolution        */
    __u32 yres;
    __u32 xres_virtual;        /* virtual resolution        */
    __u32 yres_virtual;
    __u32 xoffset;            /* offset from virtual to visible */
    __u32 yoffset;            /* resolution            */

    __u32 bits_per_pixel;        /* guess what            */
    __u32 grayscale;        /* != 0 Graylevels instead of colors */

    struct fb_bitfield red;        /* bitfield in fb mem if true color, */
    struct fb_bitfield green;    /* else only length is significant */
    struct fb_bitfield blue;
    struct fb_bitfield transp;    /* transparency            */    

    __u32 nonstd;            /* != 0 Non standard pixel format */

    __u32 activate;            /* see FB_ACTIVATE_*        */

    __u32 height;            /* height of picture in mm    */
    __u32 width;            /* width of picture in mm     */

    __u32 accel_flags;        /* (OBSOLETE) see fb_info.flags */

    /* Timing: All values in pixclocks, except pixclock (of course) */
    __u32 pixclock;            /* pixel clock in ps (pico seconds) */
    __u32 left_margin;        /* time from sync to picture    */
    __u32 right_margin;        /* time from picture to sync    */
    __u32 upper_margin;        /* time from sync to picture    */
    __u32 lower_margin;
    __u32 hsync_len;        /* length of horizontal sync    */
    __u32 vsync_len;        /* length of vertical sync    */
    __u32 sync;            /* see FB_SYNC_*        */
    __u32 vmode;            /* see FB_VMODE_*        */
    __u32 rotate;            /* angle we rotate counter clockwise */
    __u32 reserved[5];        /* Reserved for future compatibility */
};

固定参数--------

struct fb_fix_screeninfo记录了用户不能修改的显示器控制参数，如显示缓存的物理地址等。

struct fb_fix_screeninfo {
    char id[16];            /* identification string eg "TT Builtin" */
    unsigned long smem_start;    /* Start of frame buffer mem */
                    /* (physical address) */
    __u32 smem_len;            /* Length of frame buffer mem */
    __u32 type;            /* see FB_TYPE_*        */
    __u32 type_aux;            /* Interleave for interleaved Planes */
    __u32 visual;            /* see FB_VISUAL_*        */
    __u16 xpanstep;            /* zero if no hardware panning  */
    __u16 ypanstep;            /* zero if no hardware panning  */
    __u16 ywrapstep;        /* zero if no hardware ywrap    */
    __u32 line_length;        /* length of a line in bytes    */
    unsigned long mmio_start;    /* Start of Memory Mapped I/O   */
                    /* (physical address) */
    __u32 mmio_len;            /* Length of Memory Mapped I/O  */
    __u32 accel;            /* Indicate to driver which    */
                    /*  specific chip/card we have    */
    __u16 reserved[3];        /* Reserved for future compatibility */
};

操作集

struct fb_ops 包含了对控制器进行操作的函数指针。

若不实现，也可以，这时图中，file_operations结构体中的read等，是内核给我们实现好的。若实现，则会使用自己定义好的。

struct fb_ops {
    /* open/release and usage marking */
    struct module *owner;
    int (*fb_open)(struct fb_info *info, int user);
    int (*fb_release)(struct fb_info *info, int user);

    /* For framebuffers with strange non linear layouts or that do not
     * work with normal memory mapped access
     */
    ssize_t (*fb_read)(struct fb_info *info, char __user *buf,
               size_t count, loff_t *ppos);
    ssize_t (*fb_write)(struct fb_info *info, const char __user *buf,
                size_t count, loff_t *ppos);

    /* checks var and eventually tweaks it to something supported,
     * DO NOT MODIFY PAR */
    int (*fb_check_var)(struct fb_var_screeninfo *var, struct fb_info *info);

    /* set the video mode according to info->var */
    int (*fb_set_par)(struct fb_info *info);

    /* set color register */
    int (*fb_setcolreg)(unsigned regno, unsigned red, unsigned green,
                unsigned blue, unsigned transp, struct fb_info *info);

    /* set color registers in batch */
    int (*fb_setcmap)(struct fb_cmap *cmap, struct fb_info *info);

    /* blank display */
    int (*fb_blank)(int blank, struct fb_info *info);

    /* pan display */
    int (*fb_pan_display)(struct fb_var_screeninfo *var, struct fb_info *info);

    /* Draws a rectangle */
    void (*fb_fillrect) (struct fb_info *info, const struct fb_fillrect *rect);
    /* Copy data from area to another */
    void (*fb_copyarea) (struct fb_info *info, const struct fb_copyarea *region);
    /* Draws a image to the display */
    void (*fb_imageblit) (struct fb_info *info, const struct fb_image *image);

    /* Draws cursor */
    int (*fb_cursor) (struct fb_info *info, struct fb_cursor *cursor);

    /* Rotates the display */
    void (*fb_rotate)(struct fb_info *info, int angle);

    /* wait for blit idle, optional */
    int (*fb_sync)(struct fb_info *info);

    /* perform fb specific ioctl (optional) */
    int (*fb_ioctl)(struct fb_info *info, unsigned int cmd,
            unsigned long arg);

    /* Handle 32bit compat ioctl (optional) */
    int (*fb_compat_ioctl)(struct fb_info *info, unsigned cmd,
            unsigned long arg);

    /* perform fb specific mmap */
    int (*fb_mmap)(struct fb_info *info, struct vm_area_struct *vma);

    /* save current hardware state */
    void (*fb_save_state)(struct fb_info *info);

    /* restore saved state */
    void (*fb_restore_state)(struct fb_info *info);

    /* get capability given var */
    void (*fb_get_caps)(struct fb_info *info, struct fb_blit_caps *caps,
                struct fb_var_screeninfo *var);
};

                         

设备注册

int register_framebuffer(struct fb_info *fb_info)

设备注销

int unregister_framebuffer(struct fb_info *fb_info)

驱动分析-----------------------

/* linux/drivers/video/s3c2410fb.c
 *    Copyright (c) 2004,2005 Arnaud Patard
 *    Copyright (c) 2004-2008 Ben Dooks
 *
 * S3C2410 LCD Framebuffer Driver
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive for
 * more details.
 *
 * Driver based on skeletonfb.c, sa1100fb.c and others.
*/

#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/platform_device.h>
#include <linux/clk.h>

#include <asm/io.h>
#include <asm/div64.h>

#include <asm/mach/map.h>
#include <mach/regs-lcd.h>
#include <mach/regs-gpio.h>
#include <mach/fb.h>

#ifdef CONFIG_PM
#include <linux/pm.h>
#endif

#include "s3c2410fb.h"

/* Debugging stuff */
#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); }

/* useful functions */

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

/* s3c2410fb_set_lcdaddr
 *
 * initialise lcd controller address pointers
 */
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;
    saddr2  = info->fix.smem_start;
    saddr2 += info->fix.line_length * info->var.yres;
    saddr2 >>= 1;

    saddr3 = S3C2410_OFFSIZE(0) |
         S3C2410_PAGEWIDTH((info->fix.line_length / 2) & 0x3ff);

    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);
}

/* s3c2410fb_calc_pixclk()
 *
 * calculate divisor for clk->pixclk
 */
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 is in picoseconds, our clock is in Hz
     *
     * Hz -> picoseconds is / 10^-12
     */

    div = (unsigned long long)clk * pixclk;
    div >>= 12;            /* div / 2^12 */
    do_div(div, 625 * 625UL * 625); /* div / 5^12 */

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

/*
 *    s3c2410fb_check_var():
 *    Get the video params out of 'var'. If a value doesn't fit, round it up,
 *    if it's too big, return -EINVAL.
 *
 */
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;
    int type = default_display->type;
    unsigned i;

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

    /* validate x/y resolution */
    /* choose default mode if possible */
    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;
    }

    /* it is always the size as the display */
    var->xres_virtual = display->xres;
    var->yres_virtual = display->yres;
    var->height = display->height;
    var->width = display->width;

    /* copy lcd settings */
    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;
    /* set display type */
    fbi->regs.lcdcon1 = display->type;

    var->transp.offset = 0;
    var->transp.length = 0;
    /* set r/g/b positions */
    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;
}

/* s3c2410fb_calculate_stn_lcd_regs
 *
 * calculate register values from var settings
 */
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:
        /* invalid pixel depth */
        dev_err(fbi->dev, "invalid bpp %d\n",
            var->bits_per_pixel);
    }
    /* update X/Y info */
    dprintk("setting horz: lft=%d, rt=%d, sync=%d\n",
        var->left_margin, var->right_margin, var->hsync_len);

    regs->lcdcon2 = S3C2410_LCDCON2_LINEVAL(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);
}

/* s3c2410fb_calculate_tft_lcd_regs
 *
 * calculate register values from var settings
 */
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:
        /* invalid pixel depth */
        dev_err(fbi->dev, "invalid bpp %d\n",
            var->bits_per_pixel);
    }
    /* update X/Y info */
    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(var->yres - 1) |
            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);

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

/* s3c2410fb_activate_var
 *
 * activate (set) the controller from the given framebuffer
 * information
 */
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 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);

    /* write new registers */

    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);

    /* set lcd address pointers */
    s3c2410fb_set_lcdaddr(info);

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

/*
 *      s3c2410fb_set_par - Alters the hardware state.
 *      @info: frame buffer structure that represents a single frame buffer
 *
 */
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;

    /* activate this new configuration */

    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;

        /* enable IRQ */
        irqen = readl(irq_base + S3C24XX_LCDINTMSK);
        irqen &= ~S3C2410_LCDINT_FRSYNC;
        writel(irqen, irq_base + S3C24XX_LCDINTMSK);
    }

    local_irq_restore(flags);
}

/* 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 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) {
    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[regno] = val;
        }
        break;

    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));
            schedule_palette_update(fbi, regno, val);
        }

        break;

    default:
        return 1;    /* unknown type */
    }

    return 0;
}

/* s3c2410fb_lcd_enable
 *
 * shutdown the lcd controller
 */
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);
}


/*
 *      s3c2410fb_blank
 *    @blank_mode: the blank mode we want.
 *    @info: frame buffer structure that represents a single frame buffer
 *
 *    Blank the screen if blank_mode != 0, else unblank. Return 0 if
 *    blanking succeeded, != 0 if un-/blanking failed due to e.g. a
 *    video mode which doesn't support it. Implements VESA suspend
 *    and powerdown modes on hardware that supports disabling hsync/vsync:
 *
 *    Returns negative errno on error, or zero on success.
 *
 */
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);
    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;
}

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,
};

/*
 * 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 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 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);

    if (info->screen_base) {
        /* prevent initial garbage on screen */
        dprintk("map_video_memory: clear %p:%08x\n",
            info->screen_base, map_size);
        memset(info->screen_base, 0x00, map_size);

        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;
}

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);
}

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);
}

/*
 * s3c2410fb_init_registers - Initialise all LCD-related registers
 */
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;
    }

    /* Initialise LCD with values from haret */

    local_irq_save(flags);

    /* modify the gpio(s) with interrupts set (bjd) */

    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));

    /* ensure temporary palette disabled */
    writel(0x00, tpal);

    return 0;
}

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));

        /* 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[i] = PALETTE_BUFF_CLEAR;
        else
            fbi->palette_ready = 1;   /* retry */
    }
}

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)
            s3c2410fb_write_palette(fbi);

        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 = 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;

    irq = platform_get_irq(pdev, 0);
    if (irq < 0) {
        dev_err(&pdev->dev, "no irq for device\n");
        return -ENOENT;
    }

    fbinfo = framebuffer_alloc(sizeof(struct s3c2410fb_info), &pdev->dev);
    if (!fbinfo)
        return -ENOMEM;

    platform_set_drvdata(pdev, fbinfo);

    info = fbinfo->par;
    info->dev = &pdev->dev;
    info->drv_type = drv_type;

    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);
    if (info->mem == NULL) {
        dev_err(&pdev->dev, "failed to get memory region\n");
        ret = -ENOENT;
        goto dealloc_fb;
    }

    info->io = ioremap(res->start, size);
    if (info->io == NULL) {
        dev_err(&pdev->dev, "ioremap() of registers failed\n");
        ret = -ENXIO;
        goto release_mem;
    }

    info->irq_base = info->io + ((drv_type == DRV_S3C2412) ? S3C2412_LCDINTBASE : S3C2410_LCDINTBASE);

    dprintk("devinit\n");

    strcpy(fbinfo->fix.id, driver_name);

    /* Stop the video */
    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++)
        info->palette_buffer[i] = PALETTE_BUFF_CLEAR;

    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;
    }

    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;
    }

    clk_enable(info->clk);
    dprintk("got and enabled clock\n");

    msleep(1);

    /* find maximum required memory size for display */
    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;
    }

    /* Initialize video memory */
    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;

    s3c2410fb_init_registers(fbinfo);

    s3c2410fb_check_var(&fbinfo->var, fbinfo);

    ret = register_framebuffer(fbinfo);
    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);
    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);
}


/*
 *  Cleanup
 */
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

/* suspend and resume support for the lcd controller */
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);

    /* sleep before disabling the clock, we need to ensure
     * the LCD DMA engine is not going to get back on the bus
     * before the clock goes off again (bjd) */

    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);

    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)
{
    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 <[email protected]>, "
          "Ben Dooks <[email protected]>");
MODULE_DESCRIPTION("Framebuffer driver for the s3c2410");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:s3c2410-lcd");
MODULE_ALIAS("platform:s3c2412-lcd");

lcd驱动程序测试-----------

配置s3c2440 lcd驱动程序

make menuconfig ARCH=arm

device drivers------s3c2410 frame buffer support-----3.5 2410 nec support

测试--------如上实例演示