vfb.c

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/*
 *  linux/drivers/video/vfb.c -- Virtual frame buffer device
 *
 *      Copyright (C) 2002 James Simmons
 *
 *  Copyright (C) 1997 Geert Uytterhoeven
 *
 *  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.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>

#include <linux/fb.h>
#include <linux/init.h>

    /*
     *  RAM we reserve for the frame buffer. This defines the maximum screen
     *  size
     *
     *  The default can be overridden if the driver is compiled as a module
     */

#define VIDEOMEMSIZE    (1*1024*1024)   /* 1 MB */

static void *videomemory;
static u_long videomemorysize = VIDEOMEMSIZE;
module_param(videomemorysize, ulong, 0);

/**********************************************************************
 *
 * Memory management
 *
 **********************************************************************/
static void *rvmalloc(unsigned long size)
{
    void *mem;
    unsigned long adr;

    size = PAGE_ALIGN(size);
    mem = vmalloc_32(size);
    if (!mem)
        return NULL;

    memset(mem, 0, size); /* Clear the ram out, no junk to the user */
    adr = (unsigned long) mem;
    while (size > 0) {
        SetPageReserved(vmalloc_to_page((void *)adr));
        adr += PAGE_SIZE;
        size -= PAGE_SIZE;
    }

    return mem;
}

static void rvfree(void *mem, unsigned long size)
{
    unsigned long adr;

    if (!mem)
        return;

    adr = (unsigned long) mem;
    while ((long) size > 0) {
        ClearPageReserved(vmalloc_to_page((void *)adr));
        adr += PAGE_SIZE;
        size -= PAGE_SIZE;
    }
    vfree(mem);
}

static struct fb_var_screeninfo vfb_default __devinitdata = {
    .xres =     640,
    .yres =     480,
    .xres_virtual = 640,
    .yres_virtual = 480,
    .bits_per_pixel = 8,
    .red =      { 0, 8, 0 },
        .green =    { 0, 8, 0 },
        .blue =     { 0, 8, 0 },
        .activate = FB_ACTIVATE_TEST,
        .height =   -1,
        .width =    -1,
        .pixclock = 20000,
        .left_margin =  64,
        .right_margin = 64,
        .upper_margin = 32,
        .lower_margin = 32,
        .hsync_len =    64,
        .vsync_len =    2,
        .vmode =    FB_VMODE_NONINTERLACED,
};

static struct fb_fix_screeninfo vfb_fix __devinitdata = {
    .id =       "Virtual FB",
    .type =     FB_TYPE_PACKED_PIXELS,
    .visual =   FB_VISUAL_PSEUDOCOLOR,
    .xpanstep = 1,
    .ypanstep = 1,
    .ywrapstep =    1,
    .accel =    FB_ACCEL_NONE,
};

static bool vfb_enable __initdata = 0;  /* disabled by default */
module_param(vfb_enable, bool, 0);

static int vfb_check_var(struct fb_var_screeninfo *var,
             struct fb_info *info);
static int vfb_set_par(struct fb_info *info);
static int vfb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
             u_int transp, struct fb_info *info);
static int vfb_pan_display(struct fb_var_screeninfo *var,
               struct fb_info *info);
static int vfb_mmap(struct fb_info *info,
            struct vm_area_struct *vma);

static struct fb_ops vfb_ops = {
    .fb_read        = fb_sys_read,
    .fb_write       = fb_sys_write,
    .fb_check_var   = vfb_check_var,
    .fb_set_par = vfb_set_par,
    .fb_setcolreg   = vfb_setcolreg,
    .fb_pan_display = vfb_pan_display,
    .fb_fillrect    = sys_fillrect,
    .fb_copyarea    = sys_copyarea,
    .fb_imageblit   = sys_imageblit,
    .fb_mmap    = vfb_mmap,
};

    /*
     *  Internal routines
     */

static u_long get_line_length(int xres_virtual, int bpp)
{
    u_long length;

    length = xres_virtual * bpp;
    length = (length + 31) & ~31;
    length >>= 3;
    return (length);
}

    /*
     *  Setting the video mode has been split into two parts.
     *  First part, xxxfb_check_var, must not write anything
     *  to hardware, it should only verify and adjust var.
     *  This means it doesn't alter par but it does use hardware
     *  data from it to check this var. 
     */

static int vfb_check_var(struct fb_var_screeninfo *var,
             struct fb_info *info)
{
    u_long line_length;

    /*
     *  FB_VMODE_CONUPDATE and FB_VMODE_SMOOTH_XPAN are equal!
     *  as FB_VMODE_SMOOTH_XPAN is only used internally
     */

    if (var->vmode & FB_VMODE_CONUPDATE) {
        var->vmode |= FB_VMODE_YWRAP;
        var->xoffset = info->var.xoffset;
        var->yoffset = info->var.yoffset;
    }

    /*
     *  Some very basic checks
     */
    if (!var->xres)
        var->xres = 1;
    if (!var->yres)
        var->yres = 1;
    if (var->xres > var->xres_virtual)
        var->xres_virtual = var->xres;
    if (var->yres > var->yres_virtual)
        var->yres_virtual = var->yres;
    if (var->bits_per_pixel <= 1)
        var->bits_per_pixel = 1;
    else if (var->bits_per_pixel <= 8)
        var->bits_per_pixel = 8;
    else if (var->bits_per_pixel <= 16)
        var->bits_per_pixel = 16;
    else if (var->bits_per_pixel <= 24)
        var->bits_per_pixel = 24;
    else if (var->bits_per_pixel <= 32)
        var->bits_per_pixel = 32;
    else
        return -EINVAL;

    if (var->xres_virtual < var->xoffset + var->xres)
        var->xres_virtual = var->xoffset + var->xres;
    if (var->yres_virtual < var->yoffset + var->yres)
        var->yres_virtual = var->yoffset + var->yres;

    /*
     *  Memory limit
     */
    line_length =
        get_line_length(var->xres_virtual, var->bits_per_pixel);
    if (line_length * var->yres_virtual > videomemorysize)
        return -ENOMEM;

    /*
     * Now that we checked it we alter var. The reason being is that the video
     * mode passed in might not work but slight changes to it might make it 
     * work. This way we let the user know what is acceptable.
     */
    switch (var->bits_per_pixel) {
    case 1:
    case 8:
        var->red.offset = 0;
        var->red.length = 8;
        var->green.offset = 0;
        var->green.length = 8;
        var->blue.offset = 0;
        var->blue.length = 8;
        var->transp.offset = 0;
        var->transp.length = 0;
        break;
    case 16:        /* RGBA 5551 */
        if (var->transp.length) {
            var->red.offset = 0;
            var->red.length = 5;
            var->green.offset = 5;
            var->green.length = 5;
            var->blue.offset = 10;
            var->blue.length = 5;
            var->transp.offset = 15;
            var->transp.length = 1;
        } else {    /* RGB 565 */
            var->red.offset = 0;
            var->red.length = 5;
            var->green.offset = 5;
            var->green.length = 6;
            var->blue.offset = 11;
            var->blue.length = 5;
            var->transp.offset = 0;
            var->transp.length = 0;
        }
        break;
    case 24:        /* RGB 888 */
        var->red.offset = 0;
        var->red.length = 8;
        var->green.offset = 8;
        var->green.length = 8;
        var->blue.offset = 16;
        var->blue.length = 8;
        var->transp.offset = 0;
        var->transp.length = 0;
        break;
    case 32:        /* RGBA 8888 */
        var->red.offset = 0;
        var->red.length = 8;
        var->green.offset = 8;
        var->green.length = 8;
        var->blue.offset = 16;
        var->blue.length = 8;
        var->transp.offset = 24;
        var->transp.length = 8;
        break;
    }
    var->red.msb_right = 0;
    var->green.msb_right = 0;
    var->blue.msb_right = 0;
    var->transp.msb_right = 0;

    return 0;
}

/* This routine actually sets the video mode. It's in here where we
 * the hardware state info->par and fix which can be affected by the 
 * change in par. For this driver it doesn't do much. 
 */
static int vfb_set_par(struct fb_info *info)
{
    info->fix.line_length = get_line_length(info->var.xres_virtual,
                        info->var.bits_per_pixel);
    return 0;
}

    /*
     *  Set a single color register. The values supplied are already
     *  rounded down to the hardware's capabilities (according to the
     *  entries in the var structure). Return != 0 for invalid regno.
     */

static int vfb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
             u_int transp, struct fb_info *info)
{
    if (regno >= 256)   /* no. of hw registers */
        return 1;
    /*
     * Program hardware... do anything you want with transp
     */

    /* grayscale works only partially under directcolor */
    if (info->var.grayscale) {
        /* grayscale = 0.30*R + 0.59*G + 0.11*B */
        red = green = blue =
            (red * 77 + green * 151 + blue * 28) >> 8;
    }

    /* Directcolor:
     *   var->{color}.offset contains start of bitfield
     *   var->{color}.length contains length of bitfield
     *   {hardwarespecific} contains width of RAMDAC
     *   cmap[X] is programmed to (X << red.offset) | (X << green.offset) | (X << blue.offset)
     *   RAMDAC[X] is programmed to (red, green, blue)
     *
     * Pseudocolor:
     *    var->{color}.offset is 0 unless the palette index takes less than
     *                        bits_per_pixel bits and is stored in the upper
     *                        bits of the pixel value
     *    var->{color}.length is set so that 1 << length is the number of available
     *                        palette entries
     *    cmap is not used
     *    RAMDAC[X] is programmed to (red, green, blue)
     *
     * Truecolor:
     *    does not use DAC. Usually 3 are present.
     *    var->{color}.offset contains start of bitfield
     *    var->{color}.length contains length of bitfield
     *    cmap is programmed to (red << red.offset) | (green << green.offset) |
     *                      (blue << blue.offset) | (transp << transp.offset)
     *    RAMDAC does not exist
     */
#define CNVT_TOHW(val,width) ((((val)<<(width))+0x7FFF-(val))>>16)
    switch (info->fix.visual) {
    case FB_VISUAL_TRUECOLOR:
    case FB_VISUAL_PSEUDOCOLOR:
        red = CNVT_TOHW(red, info->var.red.length);
        green = CNVT_TOHW(green, info->var.green.length);
        blue = CNVT_TOHW(blue, info->var.blue.length);
        transp = CNVT_TOHW(transp, info->var.transp.length);
        break;
    case FB_VISUAL_DIRECTCOLOR:
        red = CNVT_TOHW(red, 8);    /* expect 8 bit DAC */
        green = CNVT_TOHW(green, 8);
        blue = CNVT_TOHW(blue, 8);
        /* hey, there is bug in transp handling... */
        transp = CNVT_TOHW(transp, 8);
        break;
    }
#undef CNVT_TOHW
    /* Truecolor has hardware independent palette */
    if (info->fix.visual == FB_VISUAL_TRUECOLOR) {
        u32 v;

        if (regno >= 16)
            return 1;

        v = (red << info->var.red.offset) |
            (green << info->var.green.offset) |
            (blue << info->var.blue.offset) |
            (transp << info->var.transp.offset);
        switch (info->var.bits_per_pixel) {
        case 8:
            break;
        case 16:
            ((u32 *) (info->pseudo_palette))[regno] = v;
            break;
        case 24:
        case 32:
            ((u32 *) (info->pseudo_palette))[regno] = v;
            break;
        }
        return 0;
    }
    return 0;
}

    /*
     *  Pan or Wrap the Display
     *
     *  This call looks only at xoffset, yoffset and the FB_VMODE_YWRAP flag
     */

static int vfb_pan_display(struct fb_var_screeninfo *var,
               struct fb_info *info)
{
    if (var->vmode & FB_VMODE_YWRAP) {
        if (var->yoffset < 0
            || var->yoffset >= info->var.yres_virtual
            || var->xoffset)
            return -EINVAL;
    } else {
        if (var->xoffset + info->var.xres > info->var.xres_virtual ||
            var->yoffset + info->var.yres > info->var.yres_virtual)
            return -EINVAL;
    }
    info->var.xoffset = var->xoffset;
    info->var.yoffset = var->yoffset;
    if (var->vmode & FB_VMODE_YWRAP)
        info->var.vmode |= FB_VMODE_YWRAP;
    else
        info->var.vmode &= ~FB_VMODE_YWRAP;
    return 0;
}

    /*
     *  Most drivers don't need their own mmap function 
     */

static int vfb_mmap(struct fb_info *info,
            struct vm_area_struct *vma)
{
    unsigned long start = vma->vm_start;
    unsigned long size = vma->vm_end - vma->vm_start;
    unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
    unsigned long page, pos;

    if (offset + size > info->fix.smem_len) {
        return -EINVAL;
    }

    pos = (unsigned long)info->fix.smem_start + offset;

    while (size > 0) {
        page = vmalloc_to_pfn((void *)pos);
        if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED)) {
            return -EAGAIN;
        }
        start += PAGE_SIZE;
        pos += PAGE_SIZE;
        if (size > PAGE_SIZE)
            size -= PAGE_SIZE;
        else
            size = 0;
    }

    return 0;

}

#ifndef MODULE
/*
 * The virtual framebuffer driver is only enabled if explicitly
 * requested by passing 'video=vfb:' (or any actual options).
 */
static int __init vfb_setup(char *options)
{
    char *this_opt;

    vfb_enable = 0;

    if (!options)
        return 1;

    vfb_enable = 1;

    if (!*options)
        return 1;

    while ((this_opt = strsep(&options, ",")) != NULL) {
        if (!*this_opt)
            continue;
        /* Test disable for backwards compatibility */
        if (!strcmp(this_opt, "disable"))
            vfb_enable = 0;
    }
    return 1;
}
#endif  /*  MODULE  */

    /*
     *  Initialisation
     */

static int __devinit vfb_probe(struct platform_device *dev)
{
    struct fb_info *info;
    int retval = -ENOMEM;

    /*
     * For real video cards we use ioremap.
     */
    if (!(videomemory = rvmalloc(videomemorysize)))
        return retval;

    /*
     * VFB must clear memory to prevent kernel info
     * leakage into userspace
     * VGA-based drivers MUST NOT clear memory if
     * they want to be able to take over vgacon
     */
    memset(videomemory, 0, videomemorysize);

    info = framebuffer_alloc(sizeof(u32) * 256, &dev->dev);
    if (!info)
        goto err;

    info->screen_base = (char __iomem *)videomemory;
    info->fbops = &vfb_ops;

    retval = fb_find_mode(&info->var, info, NULL,
                  NULL, 0, NULL, 8);

    if (!retval || (retval == 4))
        info->var = vfb_default;
    vfb_fix.smem_start = (unsigned long) videomemory;
    vfb_fix.smem_len = videomemorysize;
    info->fix = vfb_fix;
    info->pseudo_palette = info->par;
    info->par = NULL;
    info->flags = FBINFO_FLAG_DEFAULT;

    retval = fb_alloc_cmap(&info->cmap, 256, 0);
    if (retval < 0)
        goto err1;

    retval = register_framebuffer(info);
    if (retval < 0)
        goto err2;
    platform_set_drvdata(dev, info);

    printk(KERN_INFO
           "fb%d: Virtual frame buffer device, using %ldK of video memory\n",
           info->node, videomemorysize >> 10);
    return 0;
err2:
    fb_dealloc_cmap(&info->cmap);
err1:
    framebuffer_release(info);
err:
    rvfree(videomemory, videomemorysize);
    return retval;
}

static int vfb_remove(struct platform_device *dev)
{
    struct fb_info *info = platform_get_drvdata(dev);

    if (info) {
        unregister_framebuffer(info);
        rvfree(videomemory, videomemorysize);
        fb_dealloc_cmap(&info->cmap);
        framebuffer_release(info);
    }
    return 0;
}

static struct platform_driver vfb_driver = {
    .probe  = vfb_probe,
    .remove = vfb_remove,
    .driver = {
        .name   = "vfb",
    },
};

static struct platform_device *vfb_device;

static int __init vfb_init(void)
{
    int ret = 0;

#ifndef MODULE
    char *option = NULL;

    if (fb_get_options("vfb", &option))
        return -ENODEV;
    vfb_setup(option);
#endif

    if (!vfb_enable)
        return -ENXIO;

    ret = platform_driver_register(&vfb_driver);

    if (!ret) {
        vfb_device = platform_device_alloc("vfb", 0);

        if (vfb_device)
            ret = platform_device_add(vfb_device);
        else
            ret = -ENOMEM;

        if (ret) {
            platform_device_put(vfb_device);
            platform_driver_unregister(&vfb_driver);
        }
    }

    return ret;
}

module_init(vfb_init);

#ifdef MODULE
static void __exit vfb_exit(void)
{
    platform_device_unregister(vfb_device);
    platform_driver_unregister(&vfb_driver);
}

module_exit(vfb_exit);

MODULE_LICENSE("GPL");
#endif              /* MODULE */