video: fbdev: pmag-aa-fb: Adapt to current APIs

Rework the driver to use the current frambuffer and TURBOchannel APIs,
including proper resource management and using the new framework for
hardware cursor support.

NB two Bt431 cursor generators are included onboard, both responding at
the same TURBOchannel bus addresses and with their host data buses wired
to byte lanes #0 and #1 respectively of the 32-bit bus.  Therefore both
can be accessed simultaneously with 16-bit data transfers.  Cursor
outputs of the chip wired to lane #0 drive the respective overlay select
inputs of the Bt455 RAMDAC, whereas cursor outputs of the chip wired to
lane #1 drive the respective P3 pixel select inputs of the RAMDAC.

So 5 (out of 17) Bt455 color registers are usable with this board:
palette entries #0 and #1 for frame buffer pixel data driven while
neither cursor generator is active, palette entries #8 and #9 for frame
buffer pixel data driven while cursor generator #1 is active only and
the overlay entry while cursor generator #0 is active.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/fbdev/bt431.h

@@ -2,6 +2,7 @@
  *	linux/drivers/video/bt431.h
  *
  *	Copyright 2003  Thiemo Seufer <seufer@csv.ica.uni-stuttgart.de>
+ *	Copyright 2016  Maciej W. Rozycki <macro@linux-mips.org>
  *
  *	This file is subject to the terms and conditions of the GNU General
  *	Public License. See the file COPYING in the main directory of this
@@ -9,6 +10,8 @@
  */
 #include <linux/types.h>
 
+#define BT431_CURSOR_SIZE	64
+
 /*
  * Bt431 cursor generator registers, 32-bit aligned.
  * Two twin Bt431 are used on the DECstation's PMAG-AA.
@@ -196,27 +199,29 @@ static inline void bt431_position_cursor(struct bt431_regs *regs, u16 x, u16 y)
 	bt431_write_reg_inc(regs, (y >> 8) & 0x0f); /* BT431_REG_CYHI */
 }
 
-static inline void bt431_set_font(struct bt431_regs *regs, u8 fgc,
-				  u16 width, u16 height)
+static inline void bt431_set_cursor(struct bt431_regs *regs,
+				    const char *data, const char *mask,
+				    u16 rop, u16 width, u16 height)
 {
+	u16 x, y;
 	int i;
-	u16 fgp = fgc ? 0xffff : 0x0000;
-	u16 bgp = fgc ? 0x0000 : 0xffff;
 
+	i = 0;
+	width = DIV_ROUND_UP(width, 8);
 	bt431_select_reg(regs, BT431_REG_CRAM_BASE);
-	for (i = BT431_REG_CRAM_BASE; i <= BT431_REG_CRAM_END; i++) {
-		u16 value;
-
-		if (height << 6 <= i << 3)
-			value = bgp;
-		else if (width <= i % 8 << 3)
-			value = bgp;
-		else if (((width >> 3) & 0xffff) > i % 8)
-			value = fgp;
+	for (y = 0; y < BT431_CURSOR_SIZE; y++)
+		for (x = 0; x < BT431_CURSOR_SIZE / 8; x++) {
+			u16 val = 0;
+
+			if (y < height && x < width) {
+				val = mask[i];
+				if (rop == ROP_XOR)
+					val = (val << 8) | (val ^ data[i]);
 				else
-			value = fgp & ~(bgp << (width % 8 << 1));
-
-		bt431_write_cmap_inc(regs, value);
+					val = (val << 8) | (val & data[i]);
+				i++;
+			}
+			bt431_write_cmap_inc(regs, val);
 		}
 }