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>

2 files changed, 32 insertions, 5 deletions

diff --git a/drivers/video/atmel_lcdfb.c b/drivers/video/atmel_lcdfb.c
index 6fcf76c12910..5a31a7a40cd4 100644
--- a/drivers/video/atmel_lcdfb.c
+++ b/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;
diff --git a/include/video/atmel_lcdc.h b/include/video/atmel_lcdc.h
index 2fd9fad922e5..ed64862c4e18 100644
--- a/include/video/atmel_lcdc.h
+++ b/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);