[PATCH v2 3/5] fbdev: Add support for further video bit depths on atafb:external

[Michael Schmitz <schmitzmic@gmail.com>]

From: Miro Kropacek <miro.kropacek@gmail.com>

Supervidel offers additional video bit depths (8-bit chunky, 16-bit
RGB565 (also on the originaln Videl) and ARGB888.

Add code to support these bit depths.

Signed-off-by: Miro Kropacek <miro.kropacek@gmail.com>
Reviewed-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>
Cc: <linux-fbdev@vger.kernel.org>
Link: https://lists.debian.org/debian-68k/2026/08/msg00000.html
---
 drivers/video/fbdev/atafb.c | 89 ++++++++++++++++++++++++++++++++++---
 1 file changed, 82 insertions(+), 7 deletions(-)

diff --git a/drivers/video/fbdev/atafb.c b/drivers/video/fbdev/atafb.c
index 3d540803dc2b..50853d7a08e3 100644
--- a/drivers/video/fbdev/atafb.c
+++ b/drivers/video/fbdev/atafb.c
@@ -2081,8 +2081,12 @@ static int ext_encode_fix(struct fb_fix_screeninfo *fix, struct atafb_par *par)
 			 external_pmode == FB_TYPE_PACKED_PIXELS) ?
 				FB_VISUAL_MONO10 : FB_VISUAL_MONO01;
 	} else {
-		/* Use STATIC if we don't know how to access color registers */
-		int visual = external_vgaiobase ?
+		/* Use STATIC if we don't know how to access color registers;
+		 * SuperVidel 8bpp chunky (fb in SV RAM) uses the Falcon palette
+		 */
+		int visual = (external_vgaiobase ||
+			      (external_depth == 8 &&
+			       external_addr >= 0xa0000000)) ?
 					 FB_VISUAL_PSEUDOCOLOR :
 					 FB_VISUAL_STATIC_PSEUDOCOLOR;
 		switch (external_pmode) {
@@ -2159,6 +2163,35 @@ static int ext_encode_var(struct fb_var_screeninfo *var, struct atafb_par *par)
 	var->transp.offset = 0;
 	var->transp.length = 0;
 	var->transp.msb_right = 0;
+	if (external_pmode == -1 && external_depth == 16) {
+		/* RGB565 truecolor (e.g. SuperVidel native mode) */
+		var->red.offset = 11;
+		var->red.length = 5;
+		var->green.offset = 5;
+		var->green.length = 6;
+		var->blue.offset = 0;
+		var->blue.length = 5;
+	} else if (external_pmode == -1 && external_depth == 32) {
+		/* ARGB8888 truecolor (e.g. SuperVidel native mode) */
+		var->red.offset = 16;
+		var->red.length = 8;
+		var->green.offset = 8;
+		var->green.length = 8;
+		var->blue.offset = 0;
+		var->blue.length = 8;
+		var->transp.offset = 24;
+		var->transp.length = 8;
+	} else if (external_pmode == FB_TYPE_PACKED_PIXELS &&
+		   external_depth == 8 && external_addr >= 0xa0000000) {
+		/* SuperVidel 8bpp chunky: palette has 8 bits per channel.
+		 * Without this, fb_get_color_depth() sees length 0 and
+		 * fbcon falls back to its 2-color palette — the console
+		 * text (color 7) stays black on black.
+		 */
+		var->red.length = 8;
+		var->green.length = 8;
+		var->blue.length = 8;
+	}
 	var->yres_virtual = var->yres;
 	var->xoffset = 0;
 	var->yoffset = 0;
@@ -2193,6 +2226,38 @@ static int ext_setcolreg(unsigned int regno, unsigned int red,
 {
 	unsigned char colmask = (1 << external_bitspercol) - 1;
 
+	if (external_pmode == -1 && external_depth == 16) {
+		/* truecolor: only the pseudo palette for fbcon is needed */
+		if (regno > 15)
+			return 1;
+		((u32 *)info->pseudo_palette)[regno] = (red & 0xf800) |
+						       ((green & 0xfc00) >> 5) |
+						       ((blue & 0xf800) >> 11);
+		return 0;
+	}
+	if (external_pmode == -1 && external_depth == 32) {
+		/* ARGB8888, alpha forced opaque */
+		if (regno > 15)
+			return 1;
+		((u32 *)info->pseudo_palette)[regno] = 0xff000000 |
+						       ((red & 0xff00) << 8) |
+						       (green & 0xff00) |
+						       ((blue & 0xff00) >> 8);
+		return 0;
+	}
+	if (external_pmode == FB_TYPE_PACKED_PIXELS && external_depth == 8 &&
+	    external_addr >= 0xa0000000) {
+		/* SuperVidel native 8bpp chunky scans out via the Falcon
+		 * palette registers, honoring all 8 bits per channel
+		 */
+		if (regno > 255)
+			return 1;
+		f030_col[regno] = ((red & 0xff00) << 16) |
+				  ((green & 0xff00) << 8) |
+				  ((blue & 0xff00) >> 8);
+		return 0;
+	}
+
 	if (!external_vgaiobase)
 		return 1;
 
@@ -2422,7 +2487,9 @@ static void atafb_fillrect(struct fb_info *info, const struct fb_fillrect *rect)
 		return;
 
 #ifdef ATAFB_FALCON
-	if (info->var.bits_per_pixel == 16) {
+	/* chunky modes (Falcon hicolor, external packed/truecolor) */
+	if (info->fix.type == FB_TYPE_PACKED_PIXELS &&
+	    info->var.bits_per_pixel > 1) {
 		cfb_fillrect(info, rect);
 		return;
 	}
@@ -2463,7 +2530,9 @@ static void atafb_copyarea(struct fb_info *info, const struct fb_copyarea *area)
 	int rev_copy = 0;
 
 #ifdef ATAFB_FALCON
-	if (info->var.bits_per_pixel == 16) {
+	/* chunky modes (Falcon hicolor, external packed/truecolor) */
+	if (info->fix.type == FB_TYPE_PACKED_PIXELS &&
+	    info->var.bits_per_pixel > 1) {
 		cfb_copyarea(info, area);
 		return;
 	}
@@ -2517,7 +2586,9 @@ static void atafb_imageblit(struct fb_info *info, const struct fb_image *image)
 	u32 dx, dy, width, height, pitch;
 
 #ifdef ATAFB_FALCON
-	if (info->var.bits_per_pixel == 16) {
+	/* chunky modes (Falcon hicolor, external packed/truecolor) */
+	if (info->fix.type == FB_TYPE_PACKED_PIXELS &&
+	    info->var.bits_per_pixel > 1) {
 		cfb_imageblit(info, image);
 		return;
 	}
@@ -2753,7 +2824,7 @@ static void __init atafb_setup_ext(char *spec)
 		return;
 	depth = simple_strtoul(p, NULL, 10);
 	if (depth != 1 && depth != 2 && depth != 4 && depth != 8 &&
-	    depth != 16 && depth != 24)
+	    depth != 16 && depth != 24 && depth != 32)
 		return;
 
 	p = strsep(&spec, ";");
@@ -3131,7 +3202,11 @@ static int __init atafb_probe(struct platform_device *pdev)
 
 	atafb_set_disp(&fb_info);
 
-	fb_alloc_cmap(&(fb_info.cmap), 1 << fb_info.var.bits_per_pixel, 0);
+	/* truecolor visuals only need the 16-entry console palette; this
+	 * also avoids 1 << 32 overflowing at 32bpp
+	 */
+	fb_alloc_cmap(&(fb_info.cmap), fb_info.var.bits_per_pixel > 8 ?
+		      16 : 1 << fb_info.var.bits_per_pixel, 0);
 
 
 	dev_info(&pdev->dev, "Determined %dx%d, depth %d\n", fb_info.var.xres,
-- 
2.17.1