[PATCH] Add tdfx palette hack to offb driver

[Richard Drummond <lists@rcdrummond.net>]

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Hi All

Attached is a patch (against 2.4.20) which adds a palette hack for Voodoo3/4/5 
cards to the offb driver. It's tested and working here on a Voodoo3 and a 
Voodoo4. I'd welcome comments, though. Particularly, I think the probing for 
a Voodoo card may be a bit shaky. Basically I'm match the OF name with the 
pattern "3Dfx,Voodoo*". This may cause problems if there are Voodoo1 or 2 
cards available with OF drivers, and so need tightening up.

Cheers,
Rich

[-- Attachment #2: offb-tdfx_hack.diff --]
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--- drivers/video/offb.orig	2003-03-14 13:49:21.000000000 -0500
+++ drivers/video/offb.c	2003-03-18 23:37:35.000000000 -0500
@@ -53,7 +53,8 @@
 	cmap_M3A,	/* ATI Rage Mobility M3 Head A */
 	cmap_M3B,	/* ATI Rage Mobility M3 Head B */
 	cmap_radeon,	/* ATI Radeon */
-	cmap_gxt2000	/* IBM GXT2000 */
+	cmap_gxt2000,	/* IBM GXT2000 */
+	cmap_3dfx	/* 3Dfx Voodoo3/4/5 */
 };
 
 struct fb_info_offb {
@@ -462,6 +463,10 @@
 		unsigned long regbase = dp->addrs[0].address;
 		info->cmap_adr = ioremap(regbase + 0x6000, 0x1000);
 		info->cmap_type = cmap_gxt2000;
+	} else if (!strncmp( name, "3Dfx,Voodoo", 11)) {
+		unsigned long regbase = dp->addrs[2].address;
+		info->cmap_adr  = ioremap( regbase, 0xFF );
+		info->cmap_type = cmap_3dfx;
 	}
         fix->visual = info->cmap_adr ? FB_VISUAL_PSEUDOCOLOR
 				     : FB_VISUAL_STATIC_PSEUDOCOLOR;
@@ -679,6 +684,7 @@
     if (blank)
 	for (i = 0; i < 256; i++) {
 	    switch(info2->cmap_type) {
+		int regno;
 	    case cmap_m64:
 	        *info2->cmap_adr = i;
 	  	mach_eieio();
@@ -711,6 +717,16 @@
 	    case cmap_gxt2000:
 		out_le32((unsigned *)info2->cmap_adr + i, 0);
 		break;
+	    case cmap_3dfx:
+		/* Wait for three slots in the FIFO (is this necessary?) */
+		while((in_le32((unsigned *)info2->cmap_adr) & 0x1F) < 3 );
+		/* Is the desktop using the upper 256 entries of the CLUT? */
+		regno = (in_le32((unsigned *)info2->cmap_adr + 0x5C) & 1<<12) ?
+		    i+256 : i;
+		/* Stuff the palette index and data */
+		out_le32((unsigned *)(info2->cmap_adr + 0x50), regno);
+		out_le32((unsigned *)(info2->cmap_adr + 0x54), 0);
+		break;
 	    }
 	}
     else
@@ -800,6 +816,17 @@
 	out_le32((unsigned *)info2->cmap_adr + regno,
 		 (red << 16 | green << 8 | blue));
 	break;
+    case cmap_3dfx:
+	/* Wait for three slots in the FIFO (is this necessary?) */
+	while((in_le32((unsigned *)info2->cmap_adr) & 0x1F) < 3 );
+	/* Is the desktop using the upper 256 entries of the CLUT */
+	if((in_le32((unsigned *)info2->cmap_adr + 0x5C) & 1<<12))
+	    regno += 256;
+	/* Stuff the palette index and data */
+	out_le32((unsigned *)(info2->cmap_adr + 0x50), regno);
+	out_le32((unsigned *)(info2->cmap_adr + 0x54),
+	         (red << 16 | green << 8 | blue));
+	break;
     }
 
     if (regno < 16)