atmel_lcdfb: wiring BGR to RGB color mode

Adds different wiring mode for the LCD screen.

The legacy atmel LCDC IP uses a non standard color mode, "BGR-555.1" instead
"RGB-565".  The major part of graphic stacks for embedded systems uses only
"RGB-565".  It is possible to swap LCD IOs instead of doing this bit swapping
by software (See application note AT91SAM9 LCD Controller
http://www.atmel.com/dyn/resources/prod_documents/doc6300.pdf)

This wire swapping is done on the at91sam9rl-ek board (board code
using this patch will come later).
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Andrew Victor <avictor.za@gmail.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/atmel_lcdfb.c

@@ -338,19 +338,35 @@ static int atmel_lcdfb_check_var(struct fb_var_screeninfo *var,
 		break;
 	case 15:
 	case 16:
-		var->red.offset = 0;
+		if (sinfo->lcd_wiring_mode == ATMEL_LCDC_WIRING_RGB) {
+			/* RGB:565 mode */
+			var->red.offset = 11;
+			var->blue.offset = 0;
+			var->green.length = 6;
+		} else {
+			/* BGR:555 mode */
+			var->red.offset = 0;
+			var->blue.offset = 10;
+			var->green.length = 5;
+		}
 		var->green.offset = 5;
-		var->blue.offset = 10;
-		var->red.length = var->green.length = var->blue.length = 5;
+		var->red.length = var->blue.length = 5;
 		break;
 	case 32:
 		var->transp.offset = 24;
 		var->transp.length = 8;
 		/* fall through */
 	case 24:
-		var->red.offset = 0;
+		if (sinfo->lcd_wiring_mode == ATMEL_LCDC_WIRING_RGB) {
+			/* RGB:888 mode */
+			var->red.offset = 16;
+			var->blue.offset = 0;
+		} else {
+			/* BGR:888 mode */
+			var->red.offset = 0;
+			var->blue.offset = 16;
+		}
 		var->green.offset = 8;
-		var->blue.offset = 16;
 		var->red.length = var->green.length = var->blue.length = 8;
 		break;
 	default:
@@ -697,6 +713,7 @@ static int __init atmel_lcdfb_probe(struct platform_device *pdev)
 		sinfo->atmel_lcdfb_power_control = pdata_sinfo->atmel_lcdfb_power_control;
 		sinfo->guard_time = pdata_sinfo->guard_time;
 		sinfo->lcdcon_is_backlight = pdata_sinfo->lcdcon_is_backlight;
+		sinfo->lcd_wiring_mode = pdata_sinfo->lcd_wiring_mode;
 	} else {
 		dev_err(dev, "cannot get default configuration\n");
 		goto free_info;

include/video/atmel_lcdc.h

@@ -22,6 +22,15 @@
 #ifndef __ATMEL_LCDC_H__
 #define __ATMEL_LCDC_H__
 
+
+/* Way LCD wires are connected to the chip:
+ * Some Atmel chips use BGR color mode (instead of standard RGB)
+ * A swapped wiring onboard can bring to RGB mode.
+ */
+#define ATMEL_LCDC_WIRING_BGR	0
+#define ATMEL_LCDC_WIRING_RGB	1
+
+
  /* LCD Controller info data structure, stored in device platform_data */
 struct atmel_lcdfb_info {
 	spinlock_t		lock;
@@ -42,6 +51,7 @@ struct atmel_lcdfb_info {
 	u8			saved_lcdcon;
 
 	u8			default_bpp;
+	u8			lcd_wiring_mode;
 	unsigned int		default_lcdcon2;
 	unsigned int		default_dmacon;
 	void (*atmel_lcdfb_power_control)(int on);