/*
 *  linux/drivers/video/acornfb.c
 *
 *  Copyright (C) 1998-2001 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Frame buffer code for Acorn platforms
 *
 * NOTE: Most of the modes with X!=640 will disappear shortly.
 * NOTE: Startup setting of HS & VS polarity not supported.
 *       (do we need to support it if we're coming up in 640x480?)
 *
 * FIXME: (things broken by the "new improved" FBCON API)
 *  - Blanking 8bpp displays with VIDC
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/fb.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/io.h>

#include <mach/hardware.h>
#include <asm/irq.h>
#include <asm/mach-types.h>
#include <asm/pgtable.h>

#include "acornfb.h"

/*
 * VIDC machines can't do 16 or 32BPP modes.
 */
#ifdef HAS_VIDC
#undef FBCON_HAS_CFB16
#undef FBCON_HAS_CFB32
#endif

/*
 * Default resolution.
 * NOTE that it has to be supported in the table towards
 * the end of this file.
 */
#define DEFAULT_XRES    640
#define DEFAULT_YRES    480
#define DEFAULT_BPP     4

/*
 * define this to debug the video mode selection
 */
#undef DEBUG_MODE_SELECTION

/*
 * Translation from RISC OS monitor types to actual
 * HSYNC and VSYNC frequency ranges.  These are
 * probably not right, but they're the best info I
 * have.  Allow 1% either way on the nominal for TVs.
 */
#define NR_MONTYPES     6
static struct fb_monspecs monspecs[NR_MONTYPES] __initdata = {
        {       /* TV           */
                .hfmin  = 15469,
                .hfmax  = 15781,
                .vfmin  = 49,
                .vfmax  = 51,
        }, {    /* Multi Freq   */
                .hfmin  = 0,
                .hfmax  = 99999,
                .vfmin  = 0,
                .vfmax  = 199,
        }, {    /* Hi-res mono  */
                .hfmin  = 58608,
                .hfmax  = 58608,
                .vfmin  = 64,
                .vfmax  = 64,
        }, {    /* VGA          */
                .hfmin  = 30000,
                .hfmax  = 70000,
                .vfmin  = 60,
                .vfmax  = 60,
        }, {    /* SVGA         */
                .hfmin  = 30000,
                .hfmax  = 70000,
                .vfmin  = 56,
                .vfmax  = 75,
        }, {
                .hfmin  = 30000,
                .hfmax  = 70000,
                .vfmin  = 60,
                .vfmax  = 60,
        }
};

static struct fb_info fb_info;
static struct acornfb_par current_par;
static struct vidc_timing current_vidc;

extern unsigned int vram_size;  /* set by setup.c */

#ifdef HAS_VIDC

#define MAX_SIZE        480*1024

/* CTL     VIDC Actual
 * 24.000  0     8.000
 * 25.175  0     8.392
 * 36.000  0    12.000
 * 24.000  1    12.000
 * 25.175  1    12.588
 * 24.000  2    16.000
 * 25.175  2    16.783
 * 36.000  1    18.000
 * 24.000  3    24.000
 * 36.000  2    24.000
 * 25.175  3    25.175
 * 36.000  3    36.000
 */
struct pixclock {
        u_long  min_clock;
        u_long  max_clock;
        u_int   vidc_ctl;
        u_int   vid_ctl;
};

static struct pixclock arc_clocks[] = {
        /* we allow +/-1% on these */
        { 123750, 126250, VIDC_CTRL_DIV3,   VID_CTL_24MHz },    /*  8.000MHz */
        {  82500,  84167, VIDC_CTRL_DIV2,   VID_CTL_24MHz },    /* 12.000MHz */
        {  61875,  63125, VIDC_CTRL_DIV1_5, VID_CTL_24MHz },    /* 16.000MHz */
        {  41250,  42083, VIDC_CTRL_DIV1,   VID_CTL_24MHz },    /* 24.000MHz */
};

static struct pixclock *
acornfb_valid_pixrate(struct fb_var_screeninfo *var)
{
        u_long pixclock = var->pixclock;
        u_int i;

        if (!var->pixclock)
                return NULL;

        for (i = 0; i < ARRAY_SIZE(arc_clocks); i++)
                if (pixclock > arc_clocks[i].min_clock &&
                    pixclock < arc_clocks[i].max_clock)
                        return arc_clocks + i;

        return NULL;
}

/* VIDC Rules:
 * hcr  : must be even (interlace, hcr/2 must be even)
 * hswr : must be even
 * hdsr : must be odd
 * hder : must be odd
 *
 * vcr  : must be odd
 * vswr : >= 1
 * vdsr : >= 1
 * vder : >= vdsr
 * if interlaced, then hcr/2 must be even
 */
static void
acornfb_set_timing(struct fb_var_screeninfo *var)
{
        struct pixclock *pclk;
        struct vidc_timing vidc;
        u_int horiz_correction;
        u_int sync_len, display_start, display_end, cycle;
        u_int is_interlaced;
        u_int vid_ctl, vidc_ctl;
        u_int bandwidth;

        memset(&vidc, 0, sizeof(vidc));

        pclk = acornfb_valid_pixrate(var);
        vidc_ctl = pclk->vidc_ctl;
        vid_ctl  = pclk->vid_ctl;

        bandwidth = var->pixclock * 8 / var->bits_per_pixel;
        /* 25.175, 4bpp = 79.444ns per byte, 317.776ns per word: fifo = 2,6 */
        if (bandwidth > 143500)
                vidc_ctl |= VIDC_CTRL_FIFO_3_7;
        else if (bandwidth > 71750)
                vidc_ctl |= VIDC_CTRL_FIFO_2_6;
        else if (bandwidth > 35875)
                vidc_ctl |= VIDC_CTRL_FIFO_1_5;
        else
                vidc_ctl |= VIDC_CTRL_FIFO_0_4;

        switch (var->bits_per_pixel) {
        case 1:
                horiz_correction = 19;
                vidc_ctl |= VIDC_CTRL_1BPP;
                break;

        case 2:
                horiz_correction = 11;
                vidc_ctl |= VIDC_CTRL_2BPP;
                break;

        case 4:
                horiz_correction = 7;
                vidc_ctl |= VIDC_CTRL_4BPP;
                break;

        default:
        case 8:
                horiz_correction = 5;
                vidc_ctl |= VIDC_CTRL_8BPP;
                break;
        }

        if (var->sync & FB_SYNC_COMP_HIGH_ACT) /* should be FB_SYNC_COMP */
                vidc_ctl |= VIDC_CTRL_CSYNC;
        else {
                if (!(var->sync & FB_SYNC_HOR_HIGH_ACT))
                        vid_ctl |= VID_CTL_HS_NHSYNC;

                if (!(var->sync & FB_SYNC_VERT_HIGH_ACT))
                        vid_ctl |= VID_CTL_VS_NVSYNC;
        }

        sync_len        = var->hsync_len;
        display_start   = sync_len + var->left_margin;
        display_end     = display_start + var->xres;
        cycle           = display_end + var->right_margin;

        /* if interlaced, then hcr/2 must be even */
        is_interlaced = (var->vmode & FB_VMODE_MASK) == FB_VMODE_INTERLACED;

        if (is_interlaced) {
                vidc_ctl |= VIDC_CTRL_INTERLACE;
                if (cycle & 2) {
                        cycle += 2;
                        var->right_margin += 2;
                }
        }

        vidc.h_cycle            = (cycle - 2) / 2;
        vidc.h_sync_width       = (sync_len - 2) / 2;
        vidc.h_border_start     = (display_start - 1) / 2;
        vidc.h_display_start    = (display_start - horiz_correction) / 2;
        vidc.h_display_end      = (display_end - horiz_correction) / 2;
        vidc.h_border_end       = (display_end - 1) / 2;
        vidc.h_interlace        = (vidc.h_cycle + 1) / 2;

        sync_len        = var->vsync_len;
        display_start   = sync_len + var->upper_margin;
        display_end     = display_start + var->yres;
        cycle           = display_end + var->lower_margin;

        if (is_interlaced)
                cycle = (cycle - 3) / 2;
        else
                cycle = cycle - 1;

        vidc.v_cycle            = cycle;
        vidc.v_sync_width       = sync_len - 1;
        vidc.v_border_start     = display_start - 1;
        vidc.v_display_start    = vidc.v_border_start;
        vidc.v_display_end      = display_end - 1;
        vidc.v_border_end       = vidc.v_display_end;

        if (machine_is_a5k())
                __raw_writeb(vid_ctl, IOEB_VID_CTL);

        if (memcmp(&current_vidc, &vidc, sizeof(vidc))) {
                current_vidc = vidc;

                vidc_writel(0xe0000000 | vidc_ctl);
                vidc_writel(0x80000000 | (vidc.h_cycle << 14));
                vidc_writel(0x84000000 | (vidc.h_sync_width << 14));
                vidc_writel(0x88000000 | (vidc.h_border_start << 14));
                vidc_writel(0x8c000000 | (vidc.h_display_start << 14));
                vidc_writel(0x90000000 | (vidc.h_display_end << 14));
                vidc_writel(0x94000000 | (vidc.h_border_end << 14));
                vidc_writel(0x98000000);
                vidc_writel(0x9c000000 | (vidc.h_interlace << 14));
                vidc_writel(0xa0000000 | (vidc.v_cycle << 14));
                vidc_writel(0xa4000000 | (vidc.v_sync_width << 14));
                vidc_writel(0xa8000000 | (vidc.v_border_start << 14));
                vidc_writel(0xac000000 | (vidc.v_display_start << 14));
                vidc_writel(0xb0000000 | (vidc.v_display_end << 14));
                vidc_writel(0xb4000000 | (vidc.v_border_end << 14));
                vidc_writel(0xb8000000);
                vidc_writel(0xbc000000);
        }
#ifdef DEBUG_MODE_SELECTION
        printk(KERN_DEBUG "VIDC registers for %dx%dx%d:\n", var->xres,
               var->yres, var->bits_per_pixel);
        printk(KERN_DEBUG " H-cycle          : %d\n", vidc.h_cycle);
        printk(KERN_DEBUG " H-sync-width     : %d\n", vidc.h_sync_width);
        printk(KERN_DEBUG " H-border-start   : %d\n", vidc.h_border_start);
        printk(KERN_DEBUG " H-display-start  : %d\n", vidc.h_display_start);
        printk(KERN_DEBUG " H-display-end    : %d\n", vidc.h_display_end);
        printk(KERN_DEBUG " H-border-end     : %d\n", vidc.h_border_end);
        printk(KERN_DEBUG " H-interlace      : %d\n", vidc.h_interlace);
        printk(KERN_DEBUG " V-cycle          : %d\n", vidc.v_cycle);
        printk(KERN_DEBUG " V-sync-width     : %d\n", vidc.v_sync_width);
        printk(KERN_DEBUG " V-border-start   : %d\n", vidc.v_border_start);
        printk(KERN_DEBUG " V-display-start  : %d\n", vidc.v_display_start);
        printk(KERN_DEBUG " V-display-end    : %d\n", vidc.v_display_end);
        printk(KERN_DEBUG " V-border-end     : %d\n", vidc.v_border_end);
        printk(KERN_DEBUG " VIDC Ctrl (E)    : 0x%08X\n", vidc_ctl);
        printk(KERN_DEBUG " IOEB Ctrl        : 0x%08X\n", vid_ctl);
#endif
}

static int
acornfb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
                  u_int trans, struct fb_info *info)
{
        union palette pal;

        if (regno >= current_par.palette_size)
                return 1;

        pal.p = 0;
        pal.vidc.reg   = regno;
        pal.vidc.red   = red >> 12;
        pal.vidc.green = green >> 12;
        pal.vidc.blue  = blue >> 12;

        current_par.palette[regno] = pal;

        vidc_writel(pal.p);

        return 0;
}
#endif

#ifdef HAS_VIDC20
#include <mach/acornfb.h>

#define MAX_SIZE        2*1024*1024

/* VIDC20 has a different set of rules from the VIDC:
 *  hcr  : must be multiple of 4
 *  hswr : must be even
 *  hdsr : must be even
 *  hder : must be even
 *  vcr  : >= 2, (interlace, must be odd)
 *  vswr : >= 1
 *  vdsr : >= 1
 *  vder : >= vdsr
 */
static void acornfb_set_timing(struct fb_info *info)
{
        struct fb_var_screeninfo *var = &info->var;
        struct vidc_timing vidc;
        u_int vcr, fsize;
        u_int ext_ctl, dat_ctl;
        u_int words_per_line;

        memset(&vidc, 0, sizeof(vidc));

        vidc.h_sync_width       = var->hsync_len - 8;
        vidc.h_border_start     = vidc.h_sync_width + var->left_margin + 8 - 12;
        vidc.h_display_start    = vidc.h_border_start + 12 - 18;
        vidc.h_display_end      = vidc.h_display_start + var->xres;
        vidc.h_border_end       = vidc.h_display_end + 18 - 12;
        vidc.h_cycle            = vidc.h_border_end + var->right_margin + 12 - 8;
        vidc.h_interlace        = vidc.h_cycle / 2;
        vidc.v_sync_width       = var->vsync_len - 1;
        vidc.v_border_start     = vidc.v_sync_width + var->upper_margin;
        vidc.v_display_start    = vidc.v_border_start;
        vidc.v_display_end      = vidc.v_display_start + var->yres;
        vidc.v_border_end       = vidc.v_display_end;
        vidc.control            = acornfb_default_control();

        vcr = var->vsync_len + var->upper_margin + var->yres +
              var->lower_margin;

        if ((var->vmode & FB_VMODE_MASK) == FB_VMODE_INTERLACED) {
                vidc.v_cycle = (vcr - 3) / 2;
                vidc.control |= VIDC20_CTRL_INT;
        } else
                vidc.v_cycle = vcr - 2;

        switch (var->bits_per_pixel) {
        case  1: vidc.control |= VIDC20_CTRL_1BPP;      break;
        case  2: vidc.control |= VIDC20_CTRL_2BPP;      break;
        case  4: vidc.control |= VIDC20_CTRL_4BPP;      break;
        default:
        case  8: vidc.control |= VIDC20_CTRL_8BPP;      break;
        case 16: vidc.control |= VIDC20_CTRL_16BPP;     break;
        case 32: vidc.control |= VIDC20_CTRL_32BPP;     break;
        }

        acornfb_vidc20_find_rates(&vidc, var);
        fsize = var->vsync_len + var->upper_margin + var->lower_margin - 1;

        if (memcmp(&current_vidc, &vidc, sizeof(vidc))) {
                current_vidc = vidc;

                vidc_writel(VIDC20_CTRL| vidc.control);
                vidc_writel(0xd0000000 | vidc.pll_ctl);
                vidc_writel(0x80000000 | vidc.h_cycle);
                vidc_writel(0x81000000 | vidc.h_sync_width);
                vidc_writel(0x82000000 | vidc.h_border_start);
                vidc_writel(0x83000000 | vidc.h_display_start);
                vidc_writel(0x84000000 | vidc.h_display_end);
                vidc_writel(0x85000000 | vidc.h_border_end);
                vidc_writel(0x86000000);
                vidc_writel(0x87000000 | vidc.h_interlace);
                vidc_writel(0x90000000 | vidc.v_cycle);
                vidc_writel(0x91000000 | vidc.v_sync_width);
                vidc_writel(0x92000000 | vidc.v_border_start);
                vidc_writel(0x93000000 | vidc.v_display_start);
                vidc_writel(0x94000000 | vidc.v_display_end);
                vidc_writel(0x95000000 | vidc.v_border_end);
                vidc_writel(0x96000000);
                vidc_writel(0x97000000);
        }

        iomd_writel(fsize, IOMD_FSIZE);

        ext_ctl = acornfb_default_econtrol();

        if (var->sync & FB_SYNC_COMP_HIGH_ACT) /* should be FB_SYNC_COMP */
                ext_ctl |= VIDC20_ECTL_HS_NCSYNC | VIDC20_ECTL_VS_NCSYNC;
        else {
                if (var->sync & FB_SYNC_HOR_HIGH_ACT)
                        ext_ctl |= VIDC20_ECTL_HS_HSYNC;
                else
                        ext_ctl |= VIDC20_ECTL_HS_NHSYNC;

                if (var->sync & FB_SYNC_VERT_HIGH_ACT)
                        ext_ctl |= VIDC20_ECTL_VS_VSYNC;
                else
                        ext_ctl |= VIDC20_ECTL_VS_NVSYNC;
        }

        vidc_writel(VIDC20_ECTL | ext_ctl);

        words_per_line = var->xres * var->bits_per_pixel / 32;

        if (current_par.using_vram && info->fix.smem_len == 2048*1024)
                words_per_line /= 2;

        /* RiscPC doesn't use the VIDC's VRAM control. */
        dat_ctl = VIDC20_DCTL_VRAM_DIS | VIDC20_DCTL_SNA | words_per_line;

        /* The data bus width is dependent on both the type
         * and amount of video memory.
         *     DRAM     32bit low
         * 1MB VRAM     32bit
         * 2MB VRAM     64bit
         */
        if (current_par.using_vram && current_par.vram_half_sam == 2048)
                dat_ctl |= VIDC20_DCTL_BUS_D63_0;
        else
                dat_ctl |= VIDC20_DCTL_BUS_D31_0;

        vidc_writel(VIDC20_DCTL | dat_ctl);

#ifdef DEBUG_MODE_SELECTION
        printk(KERN_DEBUG "VIDC registers for %dx%dx%d:\n", var->xres,
               var->yres, var->bits_per_pixel);
        printk(KERN_DEBUG " H-cycle          : %d\n", vidc.h_cycle);
        printk(KERN_DEBUG " H-sync-width     : %d\n", vidc.h_sync_width);
        printk(KERN_DEBUG " H-border-start   : %d\n", vidc.h_border_start);
        printk(KERN_DEBUG " H-display-start  : %d\n", vidc.h_display_start);
        printk(KERN_DEBUG " H-display-end    : %d\n", vidc.h_display_end);
        printk(KERN_DEBUG " H-border-end     : %d\n", vidc.h_border_end);
        printk(KERN_DEBUG " H-interlace      : %d\n", vidc.h_interlace);
        printk(KERN_DEBUG " V-cycle          : %d\n", vidc.v_cycle);
        printk(KERN_DEBUG " V-sync-width     : %d\n", vidc.v_sync_width);
        printk(KERN_DEBUG " V-border-start   : %d\n", vidc.v_border_start);
        printk(KERN_DEBUG " V-display-start  : %d\n", vidc.v_display_start);
        printk(KERN_DEBUG " V-display-end    : %d\n", vidc.v_display_end);
        printk(KERN_DEBUG " V-border-end     : %d\n", vidc.v_border_end);
        printk(KERN_DEBUG " Ext Ctrl  (C)    : 0x%08X\n", ext_ctl);
        printk(KERN_DEBUG " PLL Ctrl  (D)    : 0x%08X\n", vidc.pll_ctl);
        printk(KERN_DEBUG " Ctrl      (E)    : 0x%08X\n", vidc.control);
        printk(KERN_DEBUG " Data Ctrl (F)    : 0x%08X\n", dat_ctl);
        printk(KERN_DEBUG " Fsize            : 0x%08X\n", fsize);
#endif
}

/*
 * We have to take note of the VIDC20's 16-bit palette here.
 * The VIDC20 looks up a 16 bit pixel as follows:
 *
 *   bits   111111
 *          5432109876543210
 *   red            ++++++++  (8 bits,  7 to 0)
 *  green       ++++++++      (8 bits, 11 to 4)
 *   blue   ++++++++          (8 bits, 15 to 8)
 *
 * We use a pixel which looks like:
 *
 *   bits   111111
 *          5432109876543210
 *   red               +++++  (5 bits,  4 to  0)
 *  green         +++++       (5 bits,  9 to  5)
 *   blue    +++++            (5 bits, 14 to 10)
 */
static int
acornfb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
                  u_int trans, struct fb_info *info)
{
        union palette pal;

        if (regno >= current_par.palette_size)
                return 1;

        if (regno < 16 && info->fix.visual == FB_VISUAL_DIRECTCOLOR) {
                u32 pseudo_val;

                pseudo_val  = regno << info->var.red.offset;
                pseudo_val |= regno << info->var.green.offset;
                pseudo_val |= regno << info->var.blue.offset;

                ((u32 *)info->pseudo_palette)[regno] = pseudo_val;
        }

        pal.p = 0;
        pal.vidc20.red   = red >> 8;
        pal.vidc20.green = green >> 8;
        pal.vidc20.blue  = blue >> 8;

        current_par.palette[regno] = pal;

        if (info->var.bits_per_pixel == 16) {
                int i;

                pal.p = 0;
                vidc_writel(0x10000000);
                for (i = 0; i < 256; i += 1) {
                        pal.vidc20.red   = current_par.palette[ i       & 31].vidc20.red;
                        pal.vidc20.green = current_par.palette[(i >> 1) & 31].vidc20.green;
                        pal.vidc20.blue  = current_par.palette[(i >> 2) & 31].vidc20.blue;
                        vidc_writel(pal.p);
                        /* Palette register pointer auto-increments */
                }
        } else {
                vidc_writel(0x10000000 | regno);
                vidc_writel(pal.p);
        }

        return 0;
}
#endif

/*
 * Before selecting the timing parameters, adjust
 * the resolution to fit the rules.
 */
static int
acornfb_adjust_timing(struct fb_info *info, struct fb_var_screeninfo *var, u_int fontht)
{
        u_int font_line_len, sam_size, min_size, size, nr_y;

        /* xres must be even */
        var->xres = (var->xres + 1) & ~1;

        /*
         * We don't allow xres_virtual to differ from xres
         */
        var->xres_virtual = var->xres;
        var->xoffset = 0;

        if (current_par.using_vram)
                sam_size = current_par.vram_half_sam * 2;
        else
                sam_size = 16;

        /*
         * Now, find a value for yres_virtual which allows
         * us to do ywrap scrolling.  The value of
         * yres_virtual must be such that the end of the
         * displayable frame buffer must be aligned with
         * the start of a font line.
         */
        font_line_len = var->xres * var->bits_per_pixel * fontht / 8;
        min_size = var->xres * var->yres * var->bits_per_pixel / 8;

        /*
         * If minimum screen size is greater than that we have
         * available, reject it.
         */
        if (min_size > info->fix.smem_len)
                return -EINVAL;

        /* Find int 'y', such that y * fll == s * sam < maxsize
         * y = s * sam / fll; s = maxsize / sam
         */
        for (size = info->fix.smem_len;
             nr_y = size / font_line_len, min_size <= size;
             size -= sam_size) {
                if (nr_y * font_line_len == size)
                        break;
        }
        nr_y *= fontht;

        if (var->accel_flags & FB_ACCELF_TEXT) {
                if (min_size > size) {
                        /*
                         * failed, use ypan
                         */
                        size = info->fix.smem_len;
                        var->yres_virtual = size / (font_line_len / fontht);
                } else
                        var->yres_virtual = nr_y;
        } else if (var->yres_virtual > nr_y)
                var->yres_virtual = nr_y;

        current_par.screen_end = info->fix.smem_start + size;

        /*
         * Fix yres & yoffset if needed.
         */
        if (var->yres > var->yres_virtual)
                var->yres = var->yres_virtual;

        if (var->vmode & FB_VMODE_YWRAP) {
                if (var->yoffset > var->yres_virtual)
                        var->yoffset = var->yres_virtual;
        } else {
                if (var->yoffset + var->yres > var->yres_virtual)
                        var->yoffset = var->yres_virtual - var->yres;
        }

        /* hsync_len must be even */
        var->hsync_len = (var->hsync_len + 1) & ~1;

#ifdef HAS_VIDC
        /* left_margin must be odd */
        if ((var->left_margin & 1) == 0) {
                var->left_margin -= 1;
                var->right_margin += 1;
        }

        /* right_margin must be odd */
        var->right_margin |= 1;
#elif defined(HAS_VIDC20)
        /* left_margin must be even */
        if (var->left_margin & 1) {
                var->left_margin += 1;
                var->right_margin -= 1;
        }

        /* right_margin must be even */
        if (var->right_margin & 1)
                var->right_margin += 1;
#endif

        if (var->vsync_len < 1)
                var->vsync_len = 1;

        return 0;
}

static int
acornfb_validate_timing(struct fb_var_screeninfo *var,
                        struct fb_monspecs *monspecs)
{
        unsigned long hs, vs;

        /*
         * hs(Hz) = 10^12 / (pixclock * xtotal)
         * vs(Hz) = hs(Hz) / ytotal
         *
         * No need to do long long divisions or anything
         * like that if you factor it correctly
         */
        hs = 1953125000 / var->pixclock;
        hs = hs * 512 /
             (var->xres + var->left_margin + var->right_margin + var->hsync_len);
        vs = hs /
             (var->yres + var->upper_margin + var->lower_margin + var->vsync_len);

        return (vs >= monspecs->vfmin && vs <= monspecs->vfmax &&
                hs >= monspecs->hfmin && hs <= monspecs->hfmax) ? 0 : -EINVAL;
}

static inline void
acornfb_update_dma(struct fb_info *info, struct fb_var_screeninfo *var)
{
        u_int off = var->yoffset * info->fix.line_length;

#if defined(HAS_MEMC)
        memc_write(VDMA_INIT, off >> 2);
#elif defined(HAS_IOMD)
        iomd_writel(info->fix.smem_start + off, IOMD_VIDINIT);
#endif
}

static int
acornfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
{
        u_int fontht;
        int err;

        /*
         * FIXME: Find the font height
         */
        fontht = 8;

        var->red.msb_right = 0;
        var->green.msb_right = 0;
        var->blue.msb_right = 0;
        var->transp.msb_right = 0;

        switch (var->bits_per_pixel) {
        case 1: case 2: case 4: case 8:
                var->red.offset    = 0;
                var->red.length    = var->bits_per_pixel;
                var->green         = var->red;
                var->blue          = var->red;
                var->transp.offset = 0;
                var->transp.length = 0;
                break;

#ifdef HAS_VIDC20
        case 16:
                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;
                break;

        case 32:
                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 = 4;
                break;
#endif
        default:
                return -EINVAL;
        }

        /*
         * Check to see if the pixel rate is valid.
         */
        if (!acornfb_valid_pixrate(var))
                return -EINVAL;

        /*
         * Validate and adjust the resolution to
         * match the video generator hardware.
         */
        err = acornfb_adjust_timing(info, var, fontht);
        if (err)
                return err;

        /*
         * Validate the timing against the
         * monitor hardware.
         */
        return acornfb_validate_timing(var, &info->monspecs);
}

static int acornfb_set_par(struct fb_info *info)
{
        switch (info->var.bits_per_pixel) {
        case 1:
                current_par.palette_size = 2;
                info->fix.visual = FB_VISUAL_MONO10;
                break;
        case 2:
                current_par.palette_size = 4;
                info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
                break;
        case 4:
                current_par.palette_size = 16;
                info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
                break;
        case 8:
                current_par.palette_size = VIDC_PALETTE_SIZE;
#ifdef HAS_VIDC
                info->fix.visual = FB_VISUAL_STATIC_PSEUDOCOLOR;
#else
                info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
#endif
                break;
#ifdef HAS_VIDC20
        case 16:
                current_par.palette_size = 32;
                info->fix.visual = FB_VISUAL_DIRECTCOLOR;
                break;
        case 32:
                current_par.palette_size = VIDC_PALETTE_SIZE;
                info->fix.visual = FB_VISUAL_DIRECTCOLOR;
                break;
#endif
        default:
                BUG();
        }

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

#if defined(HAS_MEMC)
        {
                unsigned long size = info->fix.smem_len - VDMA_XFERSIZE;

                memc_write(VDMA_START, 0);
                memc_write(VDMA_END, size >> 2);
        }
#elif defined(HAS_IOMD)
        {
                unsigned long start, size;
                u_int control;

                start = info->fix.smem_start;
                size  = current_par.screen_end;

                if (current_par.using_vram) {
                        size -= current_par.vram_half_sam;
                        control = DMA_CR_E | (current_par.vram_half_sam / 256);
                } else {
                        size -= 16;
                        control = DMA_CR_E | DMA_CR_D | 16;
                }

                iomd_writel(start,   IOMD_VIDSTART);
                iomd_writel(size,    IOMD_VIDEND);
                iomd_writel(control, IOMD_VIDCR);
        }
#endif

        acornfb_update_dma(info, &info->var);
        acornfb_set_timing(info);

        return 0;
}

static int
acornfb_pan_display(struct fb_var_screeninfo *var, struct fb_info *info)
{
        u_int y_bottom = var->yoffset;

        if (!(var->vmode & FB_VMODE_YWRAP))
                y_bottom += var->yres;

        BUG_ON(y_bottom > var->yres_virtual);

        acornfb_update_dma(info, var);

        return 0;
}

static struct fb_ops acornfb_ops = {
        .owner          = THIS_MODULE,
        .fb_check_var   = acornfb_check_var,
        .fb_set_par     = acornfb_set_par,
        .fb_setcolreg   = acornfb_setcolreg,
        .fb_pan_display = acornfb_pan_display,
        .fb_fillrect    = cfb_fillrect,
        .fb_copyarea    = cfb_copyarea,
        .fb_imageblit   = cfb_imageblit,
};

/*
 * Everything after here is initialisation!!!
 */
static struct fb_videomode modedb[] __initdata = {
        {       /* 320x256 @ 50Hz */
                NULL, 50,  320,  256, 125000,  92,  62,  35, 19,  38, 2,
                FB_SYNC_COMP_HIGH_ACT,
                FB_VMODE_NONINTERLACED
        }, {    /* 640x250 @ 50Hz, 15.6 kHz hsync */
                NULL, 50,  640,  250,  62500, 185, 123,  38, 21,  76, 3,
                0,
                FB_VMODE_NONINTERLACED
        }, {    /* 640x256 @ 50Hz, 15.6 kHz hsync */
                NULL, 50,  640,  256,  62500, 185, 123,  35, 18,  76, 3,
                0,
                FB_VMODE_NONINTERLACED
        }, {    /* 640x512 @ 50Hz, 26.8 kHz hsync */
                NULL, 50,  640,  512,  41667, 113,  87,  18,  1,  56, 3,
                0,
                FB_VMODE_NONINTERLACED
        }, {    /* 640x250 @ 70Hz, 31.5 kHz hsync */
                NULL, 70,  640,  250,  39722,  48,  16, 109, 88,  96, 2,
                0,
                FB_VMODE_NONINTERLACED
        }, {    /* 640x256 @ 70Hz, 31.5 kHz hsync */
                NULL, 70,  640,  256,  39722,  48,  16, 106, 85,  96, 2,
                0,
                FB_VMODE_NONINTERLACED
        }, {    /* 640x352 @ 70Hz, 31.5 kHz hsync */
                NULL, 70,  640,  352,  39722,  48,  16,  58, 37,  96, 2,
                0,
                FB_VMODE_NONINTERLACED
        }, {    /* 640x480 @ 60Hz, 31.5 kHz hsync */
                NULL, 60,  640,  480,  39722,  48,  16,  32, 11,  96, 2,
                0,
                FB_VMODE_NONINTERLACED
        }, {    /* 800x600 @ 56Hz, 35.2 kHz hsync */
                NULL, 56,  800,  600,  27778, 101,  23,  22,  1, 100, 2,
                0,
                FB_VMODE_NONINTERLACED
        }, {    /* 896x352 @ 60Hz, 21.8 kHz hsync */
                NULL, 60,  896,  352,  41667,  59,  27,   9,  0, 118, 3,
                0,
                FB_VMODE_NONINTERLACED
        }, {    /* 1024x 768 @ 60Hz, 48.4 kHz hsync */
                NULL, 60, 1024,  768,  15385, 160,  24,  29,  3, 136, 6,
                0,
                FB_VMODE_NONINTERLACED
        }, {    /* 1280x1024 @ 60Hz, 63.8 kHz hsync */
                NULL, 60, 1280, 1024,   9090, 186,  96,  38,  1, 160, 3,
                0,
                FB_VMODE_NONINTERLACED
        }
};

static struct fb_videomode __initdata
acornfb_default_mode = {
        .name =         NULL,
        .refresh =      60,
        .xres =         640,
        .yres =         480,
        .pixclock =     39722,
        .left_margin =  56,
        .right_margin = 16,
        .upper_margin = 34,
        .lower_margin = 9,
        .hsync_len =    88,
        .vsync_len =    2,
        .sync =         0,
        .vmode =        FB_VMODE_NONINTERLACED
};

static void __init acornfb_init_fbinfo(void)
{
        static int first = 1;

        if (!first)
                return;
        first = 0;

        fb_info.fbops           = &acornfb_ops;
        fb_info.flags           = FBINFO_DEFAULT | FBINFO_HWACCEL_YPAN;
        fb_info.pseudo_palette  = current_par.pseudo_palette;

        strcpy(fb_info.fix.id, "Acorn");
        fb_info.fix.type        = FB_TYPE_PACKED_PIXELS;
        fb_info.fix.type_aux    = 0;
        fb_info.fix.xpanstep    = 0;
        fb_info.fix.ypanstep    = 1;
        fb_info.fix.ywrapstep   = 1;
        fb_info.fix.line_length = 0;
        fb_info.fix.accel       = FB_ACCEL_NONE;

        /*
         * setup initial parameters
         */
        memset(&fb_info.var, 0, sizeof(fb_info.var));

#if defined(HAS_VIDC20)
        fb_info.var.red.length     = 8;
        fb_info.var.transp.length  = 4;
#elif defined(HAS_VIDC)
        fb_info.var.red.length     = 4;
        fb_info.var.transp.length  = 1;
#endif
        fb_info.var.green          = fb_info.var.red;
        fb_info.var.blue           = fb_info.var.red;
        fb_info.var.nonstd         = 0;
        fb_info.var.activate       = FB_ACTIVATE_NOW;
        fb_info.var.height         = -1;
        fb_info.var.width          = -1;
        fb_info.var.vmode          = FB_VMODE_NONINTERLACED;
        fb_info.var.accel_flags    = FB_ACCELF_TEXT;

        current_par.dram_size      = 0;
        current_par.montype        = -1;
        current_par.dpms           = 0;
}

/*
 * setup acornfb options:
 *
 *  mon:hmin-hmax:vmin-vmax:dpms:width:height
 *      Set monitor parameters:
 *              hmin   = horizontal minimum frequency (Hz)
 *              hmax   = horizontal maximum frequency (Hz)      (optional)
 *              vmin   = vertical minimum frequency (Hz)
 *              vmax   = vertical maximum frequency (Hz)        (optional)

 *              dpms   = DPMS supported?                        (optional)
 *              width  = width of picture in mm.                (optional)
 *              height = height of picture in mm.               (optional)
 *
 * montype:type
 *      Set RISC-OS style monitor type:
 *              0 (or tv)       - TV frequency
 *              1 (or multi)    - Multi frequency
 *              2 (or hires)    - Hi-res monochrome
 *              3 (or vga)      - VGA
 *              4 (or svga)     - SVGA
 *              auto, or option missing
 *                              - try hardware detect
 *
 * dram:size
 *      Set the amount of DRAM to use for the frame buffer
 *      (even if you have VRAM).
 *      size can optionally be followed by 'M' or 'K' for
 *      MB or KB respectively.
 */
static void __init
acornfb_parse_mon(char *opt)
{
        char *p = opt;

        current_par.montype = -2;

        fb_info.monspecs.hfmin = simple_strtoul(p, &p, 0);
        if (*p == '-')
                fb_info.monspecs.hfmax = simple_strtoul(p + 1, &p, 0);
        else
                fb_info.monspecs.hfmax = fb_info.monspecs.hfmin;

        if (*p != ':')
                goto bad;

        fb_info.monspecs.vfmin = simple_strtoul(p + 1, &p, 0);
        if (*p == '-')
                fb_info.monspecs.vfmax = simple_strtoul(p + 1, &p, 0);
        else
                fb_info.monspecs.vfmax = fb_info.monspecs.vfmin;

        if (*p != ':')
                goto check_values;

        fb_info.monspecs.dpms = simple_strtoul(p + 1, &p, 0);

        if (*p != ':')
                goto check_values;

        fb_info.var.width = simple_strtoul(p + 1, &p, 0);

        if (*p != ':')
                goto check_values;

        fb_info.var.height = simple_strtoul(p + 1, NULL, 0);

check_values:
        if (fb_info.monspecs.hfmax < fb_info.monspecs.hfmin ||
            fb_info.monspecs.vfmax < fb_info.monspecs.vfmin)
                goto bad;
        return;

bad:
        printk(KERN_ERR "Acornfb: bad monitor settings: %s\n", opt);
        current_par.montype = -1;
}

static void __init
acornfb_parse_montype(char *opt)
{
        current_par.montype = -2;

        if (strncmp(opt, "tv", 2) == 0) {
                opt += 2;
                current_par.montype = 0;
        } else if (strncmp(opt, "multi", 5) == 0) {
                opt += 5;
                current_par.montype = 1;
        } else if (strncmp(opt, "hires", 5) == 0) {
                opt += 5;
                current_par.montype = 2;
        } else if (strncmp(opt, "vga", 3) == 0) {
                opt += 3;
                current_par.montype = 3;
        } else if (strncmp(opt, "svga", 4) == 0) {
                opt += 4;
                current_par.montype = 4;
        } else if (strncmp(opt, "auto", 4) == 0) {
                opt += 4;
                current_par.montype = -1;
        } else if (isdigit(*opt))
                current_par.montype = simple_strtoul(opt, &opt, 0);

        if (current_par.montype == -2 ||
            current_par.montype > NR_MONTYPES) {
                printk(KERN_ERR "acornfb: unknown monitor type: %s\n",
                        opt);
                current_par.montype = -1;
        } else
        if (opt && *opt) {
                if (strcmp(opt, ",dpms") == 0)
                        current_par.dpms = 1;
                else
                        printk(KERN_ERR
                               "acornfb: unknown monitor option: %s\n",
                               opt);
        }
}

static void __init
acornfb_parse_dram(char *opt)
{
        unsigned int size;

        size = simple_strtoul(opt, &opt, 0);

        if (opt) {
                switch (*opt) {
                case 'M':
                case 'm':
                        size *= 1024;
                case 'K':
                case 'k':
                        size *= 1024;
                default:
                        break;
                }
        }

        current_par.dram_size = size;
}

static struct options {
        char *name;
        void (*parse)(char *opt);
} opt_table[] __initdata = {
        { "mon",     acornfb_parse_mon     },
        { "montype", acornfb_parse_montype },
        { "dram",    acornfb_parse_dram    },
        { NULL, NULL }
};

int __init
acornfb_setup(char *options)
{
        struct options *optp;
        char *opt;

        if (!options || !*options)
                return 0;

        acornfb_init_fbinfo();

        while ((opt = strsep(&options, ",")) != NULL) {
                if (!*opt)
                        continue;

                for (optp = opt_table; optp->name; optp++) {
                        int optlen;

                        optlen = strlen(optp->name);

                        if (strncmp(opt, optp->name, optlen) == 0 &&
                            opt[optlen] == ':') {
                                optp->parse(opt + optlen + 1);
                                break;
                        }
                }

                if (!optp->name)
                        printk(KERN_ERR "acornfb: unknown parameter: %s\n",
                               opt);
        }
        return 0;
}

/*
 * Detect type of monitor connected
 *  For now, we just assume SVGA
 */
static int __init
acornfb_detect_monitortype(void)
{
        return 4;
}

/*
 * This enables the unused memory to be freed on older Acorn machines.
 * We are freeing memory on behalf of the architecture initialisation
 * code here.
 */
static inline void
free_unused_pages(unsigned int virtual_start, unsigned int virtual_end)
{
        int mb_freed = 0;

        /*
         * Align addresses
         */
        virtual_start = PAGE_ALIGN(virtual_start);
        virtual_end = PAGE_ALIGN(virtual_end);

        while (virtual_start < virtual_end) {
                struct page *page;

                /*
                 * Clear page reserved bit,
                 * set count to 1, and free
                 * the page.
                 */
                page = virt_to_page(virtual_start);
                ClearPageReserved(page);
                init_page_count(page);
                free_page(virtual_start);

                virtual_start += PAGE_SIZE;
                mb_freed += PAGE_SIZE / 1024;
        }

        printk("acornfb: freed %dK memory\n", mb_freed);
}

static int __init acornfb_probe(struct platform_device *dev)
{
        unsigned long size;
        u_int h_sync, v_sync;
        int rc, i;
        char *option = NULL;

        if (fb_get_options("acornfb", &option))
                return -ENODEV;
        acornfb_setup(option);

        acornfb_init_fbinfo();

        current_par.dev = &dev->dev;

        if (current_par.montype == -1)
                current_par.montype = acornfb_detect_monitortype();

        if (current_par.montype == -1 || current_par.montype > NR_MONTYPES)
                current_par.montype = 4;

        if (current_par.montype >= 0) {
                fb_info.monspecs = monspecs[current_par.montype];
                fb_info.monspecs.dpms = current_par.dpms;
        }

        /*
         * Try to select a suitable default mode
         */
        for (i = 0; i < ARRAY_SIZE(modedb); i++) {
                unsigned long hs;

                hs = modedb[i].refresh *
                     (modedb[i].yres + modedb[i].upper_margin +
                      modedb[i].lower_margin + modedb[i].vsync_len);
                if (modedb[i].xres == DEFAULT_XRES &&
                    modedb[i].yres == DEFAULT_YRES &&
                    modedb[i].refresh >= fb_info.monspecs.vfmin &&
                    modedb[i].refresh <= fb_info.monspecs.vfmax &&
                    hs                >= fb_info.monspecs.hfmin &&
                    hs                <= fb_info.monspecs.hfmax) {
                        acornfb_default_mode = modedb[i];
                        break;
                }
        }

        fb_info.screen_base    = (char *)SCREEN_BASE;
        fb_info.fix.smem_start = SCREEN_START;
        current_par.using_vram = 0;

        /*
         * If vram_size is set, we are using VRAM in
         * a Risc PC.  However, if the user has specified
         * an amount of DRAM then use that instead.
         */
        if (vram_size && !current_par.dram_size) {
                size = vram_size;
                current_par.vram_half_sam = vram_size / 1024;
                current_par.using_vram = 1;
        } else if (current_par.dram_size)
                size = current_par.dram_size;
        else
                size = MAX_SIZE;

        /*
         * Limit maximum screen size.
         */
        if (size > MAX_SIZE)
                size = MAX_SIZE;

        size = PAGE_ALIGN(size);

#if defined(HAS_VIDC20)
        if (!current_par.using_vram) {
                dma_addr_t handle;
                void *base;

                /*
                 * RiscPC needs to allocate the DRAM memory
                 * for the framebuffer if we are not using
                 * VRAM.
                 */
                base = dma_alloc_writecombine(current_par.dev, size, &handle,
                                              GFP_KERNEL);
                if (base == NULL) {
                        printk(KERN_ERR "acornfb: unable to allocate screen "
                               "memory\n");
                        return -ENOMEM;
                }

                fb_info.screen_base = base;
                fb_info.fix.smem_start = handle;
        }
#endif
#if defined(HAS_VIDC)
        /*
         * Archimedes/A5000 machines use a fixed address for their
         * framebuffers.  Free unused pages
         */
        free_unused_pages(PAGE_OFFSET + size, PAGE_OFFSET + MAX_SIZE);
#endif

        fb_info.fix.smem_len = size;
        current_par.palette_size   = VIDC_PALETTE_SIZE;

        /*
         * Lookup the timing for this resolution.  If we can't
         * find it, then we can't restore it if we change
         * the resolution, so we disable this feature.
         */
        do {
                rc = fb_find_mode(&fb_info.var, &fb_info, NULL, modedb,
                                 ARRAY_SIZE(modedb),
                                 &acornfb_default_mode, DEFAULT_BPP);
                /*
                 * If we found an exact match, all ok.
                 */
                if (rc == 1)
                        break;

                rc = fb_find_mode(&fb_info.var, &fb_info, NULL, NULL, 0,
                                  &acornfb_default_mode, DEFAULT_BPP);
                /*
                 * If we found an exact match, all ok.
                 */
                if (rc == 1)
                        break;

                rc = fb_find_mode(&fb_info.var, &fb_info, NULL, modedb,
                                 ARRAY_SIZE(modedb),
                                 &acornfb_default_mode, DEFAULT_BPP);
                if (rc)
                        break;

                rc = fb_find_mode(&fb_info.var, &fb_info, NULL, NULL, 0,
                                  &acornfb_default_mode, DEFAULT_BPP);
        } while (0);

        /*
         * If we didn't find an exact match, try the
         * generic database.
         */
        if (rc == 0) {
                printk("Acornfb: no valid mode found\n");
                return -EINVAL;
        }

        h_sync = 1953125000 / fb_info.var.pixclock;
        h_sync = h_sync * 512 / (fb_info.var.xres + fb_info.var.left_margin +
                 fb_info.var.right_margin + fb_info.var.hsync_len);
        v_sync = h_sync / (fb_info.var.yres + fb_info.var.upper_margin +
                 fb_info.var.lower_margin + fb_info.var.vsync_len);

        printk(KERN_INFO "Acornfb: %dkB %cRAM, %s, using %dx%d, "
                "%d.%03dkHz, %dHz\n",
                fb_info.fix.smem_len / 1024,
                current_par.using_vram ? 'V' : 'D',
                VIDC_NAME, fb_info.var.xres, fb_info.var.yres,
                h_sync / 1000, h_sync % 1000, v_sync);

        printk(KERN_INFO "Acornfb: Monitor: %d.%03d-%d.%03dkHz, %d-%dHz%s\n",
                fb_info.monspecs.hfmin / 1000, fb_info.monspecs.hfmin % 1000,
                fb_info.monspecs.hfmax / 1000, fb_info.monspecs.hfmax % 1000,
                fb_info.monspecs.vfmin, fb_info.monspecs.vfmax,
                fb_info.monspecs.dpms ? ", DPMS" : "");

        if (fb_set_var(&fb_info, &fb_info.var))
                printk(KERN_ERR "Acornfb: unable to set display parameters\n");

        if (register_framebuffer(&fb_info) < 0)
                return -EINVAL;
        return 0;
}

static struct platform_driver acornfb_driver = {
        .probe  = acornfb_probe,
        .driver = {
                .name   = "acornfb",
        },
};

static int __init acornfb_init(void)
{
        return platform_driver_register(&acornfb_driver);
}

module_init(acornfb_init);

MODULE_AUTHOR("Russell King");
MODULE_DESCRIPTION("VIDC 1/1a/20 framebuffer driver");
MODULE_LICENSE("GPL");