* Brooktree Bt485 Monolithic True-Color RAMDAC.

#include <u.h>
#include <libc.h>
#include <bio.h>

#include "pci.h"
#include "vga.h"

/*
* Brooktree Bt485 Monolithic True-Color RAMDAC.
* Assumes hooked up to an S3 86C928.
*
* There are only 16 directly addressable registers,
* Cmd3 is accessed indirectly and overlays the
* status register. We make this register index 0x1A.
* Cmd4 is an artifact of the Tvp3025 in Bt485
* emulation mode.
*/
enum {
AddrW = 0x00, /* Address register; palette/cursor RAM write */
Palette = 0x01, /* 6/8-bit color palette data */
Pmask = 0x02, /* Pixel mask register */
AddrR = 0x03, /* Address register; palette/cursor RAM read */
ColorW = 0x04, /* Address register; cursor/overscan color write */
Color = 0x05, /* Cursor/overscan color data */
Cmd0 = 0x06, /* Command register 0 */
ColorR = 0x07, /* Address register; cursor/overscan color read */
Cmd1 = 0x08, /* Command register 1 */
Cmd2 = 0x09, /* Command register 2 */
Status = 0x0A, /* Status */
Cram = 0x0B, /* Cursor RAM array data */
Cxlr = 0x0C, /* Cursor x-low register */
Cxhr = 0x0D, /* Cursor x-high register */
Cylr = 0x0E, /* Cursor y-low register */
Cyhr = 0x0F, /* Cursor y-high register */

Nreg = 0x10,

Cmd3 = 0x1A, /* Command register 3 */
Cmd4 = 0x2A, /* Command register 4 */
};

static uchar
bt485io(uchar reg)
{
uchar crt55, cr0;

if(reg >= Nreg && (reg & 0x0F) != Status)
error("%s: bad reg - 0x%X\n", bt485.name, reg);

crt55 = vgaxi(Crtx, 0x55) & 0xFC;
if((reg & 0x0F) == Status){
/*
* 1,2: Set indirect addressing for Status or
* Cmd[34] - set bit7 of Cr0.
*/
vgaxo(Crtx, 0x55, crt55|((Cmd0>>2) & 0x03));
cr0 = vgai(dacxreg[Cmd0 & 0x03])|0x80;
vgao(dacxreg[Cmd0 & 0x03], cr0);

/*
* 3,4: Set the index into the Write register,
* index == 0x00 for Status, 0x01 for Cmd3,
* 0x02 for Cmd4.
*/
vgaxo(Crtx, 0x55, crt55|((AddrW>>2) & 0x03));
vgao(dacxreg[AddrW & 0x03], (reg>>4) & 0x0F);

/*
* 5,6: Get the contents of the appropriate
* register at 0x0A.
*/
}

return crt55;
}

uchar
bt485i(uchar reg)
{
uchar crt55, r;

crt55 = bt485io(reg);
vgaxo(Crtx, 0x55, crt55|((reg>>2) & 0x03));
r = vgai(dacxreg[reg & 0x03]);
vgaxo(Crtx, 0x55, crt55);

return r;
}

void
bt485o(uchar reg, uchar data)
{
uchar crt55;

crt55 = bt485io(reg);
vgaxo(Crtx, 0x55, crt55|((reg>>2) & 0x03));
vgao(dacxreg[reg & 0x03], data);
vgaxo(Crtx, 0x55, crt55);
}

static void
options(Vga*, Ctlr* ctlr)
{
ctlr->flag |= Hsid32|Hclk2|Hextsid|Henhanced|Foptions;
}

static void
init(Vga* vga, Ctlr* ctlr)
{
ulong grade;
char *p;

/*
* Work out the part speed-grade from name. Name can have,
* e.g. '-135' on the end for 135MHz part.
*/
grade = 110000000;
if(p = strrchr(ctlr->name, '-'))
grade = strtoul(p+1, 0, 0) * 1000000;

/*
* If we don't already have a desired pclk,
* take it from the mode.
* Check it's within range.
*/
if(vga->f[0] == 0)
vga->f[0] = vga->mode->frequency;
if(vga->f[0] > grade)
error("%s: invalid pclk - %ld\n", ctlr->name, vga->f[0]);

/*
* Determine whether to use clock-doubler or not.
*/
if((ctlr->flag & Uclk2) == 0 && vga->f[0] > 67500000){
vga->f[0] /= 2;
resyncinit(vga, ctlr, Uclk2, 0);
}

ctlr->flag |= Finit;
}

static void
load(Vga*, Ctlr* ctlr)
{
uchar x;

/*
* Put the chip to sleep before (possibly) changing the clock-source
* to ensure the integrity of the palette.
*/
x = bt485i(Cmd0);
bt485o(Cmd0, x|0x01); /* sleep mode */

/*
* Set the clock-source, clock-doubler and frequency
* appropriately:
* if using the pixel-port, use Pclock1;
* use the doubler if fvco > 67.5MHz.
* set the frequency.
*/
x = bt485i(Cmd2);
if(ctlr->flag & Uenhanced)
x |= 0x10; /* Pclock1 */
else
x &= ~0x10;
bt485o(Cmd2, x);

x = bt485i(Cmd3);
if(ctlr->flag & Uclk2)
x |= 0x08; /* clock-doubler */
else
x &= ~0x08;
bt485o(Cmd3, x);

/*
* Set 4:1 multiplex and portselect bits on the
* Bt485 appropriately for using the pixel-port.
*/
x = bt485i(Cmd2);
if(ctlr->flag & Uenhanced){
bt485o(Cmd1, 0x40); /* 4:1 multiplex */
x |= 0x20; /* portselect */
}
else{
bt485o(Cmd1, 0x00);
x &= ~0x20;
}
bt485o(Cmd2, x);

x = bt485i(Cmd4);
if(ctlr->flag & Uenhanced)
x |= 0x01;
else
x &= ~0x01;
bt485o(Cmd4, x);

/*
* All done, wake the chip back up.
* Set 6/8-bit colour as appropriate.
*/
x = bt485i(Cmd0) & ~0x01;
/*if(vga->mode.z == 8)
x |= 0x02;
else*/
x &= ~0x02;
bt485o(Cmd0, x);

ctlr->flag |= Fload;
}

static void
dump(Vga*, Ctlr* ctlr)
{
int i;

printitem(ctlr->name, "direct");
for(i = 0; i < 0x10; i++)
printreg(bt485i(i));
printitem(ctlr->name, "indirect");
printreg(bt485i(Cmd3));
printreg(bt485i(Cmd4));
}

Ctlr bt485 = {
"bt485", /* name */
0, /* snarf */
options, /* options */
init, /* init */
load, /* load */
dump, /* dump */
};