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acornfb.c

/*
 *  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/init.h>
#include <linux/fb.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>

#include <asm/hardware.h>
#include <asm/io.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 <asm/arch/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;
}

/*
 * Note that we are entered with the kernel locked.
 */
static int
acornfb_mmap(struct fb_info *info, struct vm_area_struct *vma)
{
      unsigned long off, start;
      u32 len;

      off = vma->vm_pgoff << PAGE_SHIFT;

      start = info->fix.smem_start;
      len = PAGE_ALIGN(start & ~PAGE_MASK) + info->fix.smem_len;
      start &= PAGE_MASK;
      if ((vma->vm_end - vma->vm_start + off) > len)
            return -EINVAL;
      off += start;
      vma->vm_pgoff = off >> PAGE_SHIFT;

      /* This is an IO map - tell maydump to skip this VMA */
      vma->vm_flags |= VM_IO;

      vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);

      /*
       * Don't alter the page protection flags; we want to keep the area
       * cached for better performance.  This does mean that we may miss
       * some updates to the screen occasionally, but process switches
       * should cause the caches and buffers to be flushed often enough.
       */
      if (io_remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT,
                        vma->vm_end - vma->vm_start,
                        vma->vm_page_prot))
            return -EAGAIN;
      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,
      .fb_mmap    = acornfb_mmap,
};

/*
 * 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");

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