/*
 *  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);
MODULE_PARM_DESC(videomemorysize, "RAM available to frame buffer (in bytes)");

static char *mode_option = NULL;
module_param(mode_option, charp, 0);
MODULE_PARM_DESC(mode_option, "Preferred video mode (e.g. 640x480-8@60)");

static const struct fb_videomode vfb_default = {
        .xres =         640,
        .yres =         480,
        .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 = {
        .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);
MODULE_PARM_DESC(vfb_enable, "Enable Virtual FB driver");

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 const 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)
{
        switch (info->var.bits_per_pixel) {
        case 1:
                info->fix.visual = FB_VISUAL_MONO01;
                break;
        case 8:
                info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
                break;
        case 16:
        case 24:
        case 32:
                info->fix.visual = FB_VISUAL_TRUECOLOR;
                break;
        }

        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 >= 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)
{
        return remap_vmalloc_range(vma, (void *)info->fix.smem_start, vma->vm_pgoff);
}

#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;
                else
                        mode_option = this_opt;
        }
        return 1;
}
#endif  /*  MODULE  */

    /*
     *  Initialisation
     */

static int vfb_probe(struct platform_device *dev)
{
        struct fb_info *info;
        unsigned int size = PAGE_ALIGN(videomemorysize);
        int retval = -ENOMEM;

        /*
         * For real video cards we use ioremap.
         */
        if (!(videomemory = vmalloc_32_user(size)))
                return retval;

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

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

        if (!fb_find_mode(&info->var, info, mode_option,
                          NULL, 0, &vfb_default, 8)){
                fb_err(info, "Unable to find usable video mode.\n");
                retval = -EINVAL;
                goto err1;
        }

        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);

        vfb_set_par(info);

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

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

        if (info) {
                unregister_framebuffer(info);
                vfree(videomemory);
                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 */