fbdev/cirrusfb: Add support for "64 MiB" version of Picasso IV

Some Village Tronic Picasso IV graphics cards identify as a 64 MiB Zorro
device in Zorro III mode.

While the total graphics memory size is the same on such cards, the offset
of the graphics memory differs. Add a quirk to handle this.

Based on src/sys/arch/amiga/dev/grf_cl.c from NetBSD.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>

drivers/video/cirrusfb.c

@@ -314,7 +314,7 @@ static const struct zorrocl zcl_picasso4_z3 __devinitconst = {
 	.type		= BT_PICASSO4,
 	.regoffset	= 0x00600000,
 	.ramsize	= 4 * MB_,
-	.ramoffset	= 0x01000000,
+	.ramoffset	= 0x01000000,	/* 0x02000000 for 64 MiB boards */
 };
 
 static const struct zorrocl zcl_picasso4_z2 __devinitconst = {
@@ -2259,6 +2259,10 @@ static int __devinit cirrusfb_zorro_register(struct zorro_dev *z,
 	ramsize = zcl->ramsize;
 	if (ramsize) {
 		rambase = zorro_resource_start(z) + zcl->ramoffset;
+		if (zorro_resource_len(z) == 64 * MB_) {
+			/* Quirk for 64 MiB Picasso IV */
+			rambase += zcl->ramoffset;
+		}
 	} else {
 		struct zorro_dev *ram = zorro_find_device(zcl->ramid, NULL);
 		if (!ram || !zorro_resource_len(ram)) {