video: s3c-fb: add alpha value width setting

This patch adds alpha value width setting according to
transparency value of each window format, using BLENDCON
register. When alpha value is 8 bits, BLENDCON will set
alpha value width as 8 bits.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>

arch/arm/plat-samsung/include/plat/regs-fb.h

@@ -384,3 +384,9 @@
 #define WPALCON_W0PAL_16BPP_A555		(0x5 << 0)
 #define WPALCON_W0PAL_16BPP_565			(0x6 << 0)
 
+/* Blending equation control */
+#define BLENDCON				(0x260)
+#define BLENDCON_NEW_MASK			(1 << 0)
+#define BLENDCON_NEW_8BIT_ALPHA_VALUE		(1 << 0)
+#define BLENDCON_NEW_4BIT_ALPHA_VALUE		(0 << 0)
+

drivers/video/s3c-fb.c

@@ -82,6 +82,7 @@ struct s3c_fb;
  * @palette: Address of palette memory, or 0 if none.
  * @has_prtcon: Set if has PRTCON register.
  * @has_shadowcon: Set if has SHADOWCON register.
+ * @has_blendcon: Set if has BLENDCON register.
  * @has_clksel: Set if VIDCON0 register has CLKSEL bit.
  */
 struct s3c_fb_variant {
@@ -100,6 +101,7 @@ struct s3c_fb_variant {
 
 	unsigned int	has_prtcon:1;
 	unsigned int	has_shadowcon:1;
+	unsigned int	has_blendcon:1;
 	unsigned int	has_clksel:1;
 };
 
@@ -691,6 +693,17 @@ static int s3c_fb_set_par(struct fb_info *info)
 	writel(data, regs + sfb->variant.wincon + (win_no * 4));
 	writel(0x0, regs + sfb->variant.winmap + (win_no * 4));
 
+	/* Set alpha value width */
+	if (sfb->variant.has_blendcon) {
+		data = readl(sfb->regs + BLENDCON);
+		data &= ~BLENDCON_NEW_MASK;
+		if (var->transp.length > 4)
+			data |= BLENDCON_NEW_8BIT_ALPHA_VALUE;
+		else
+			data |= BLENDCON_NEW_4BIT_ALPHA_VALUE;
+		writel(data, sfb->regs + BLENDCON);
+	}
+
 	shadow_protect_win(win, 0);
 
 	pm_runtime_put_sync(sfb->dev);
@@ -1798,6 +1811,7 @@ static struct s3c_fb_driverdata s3c_fb_data_s5pc100 = {
 		},
 
 		.has_prtcon	= 1,
+		.has_blendcon	= 1,
 		.has_clksel	= 1,
 	},
 	.win[0]	= &s3c_fb_data_s5p_wins[0],
@@ -1829,6 +1843,7 @@ static struct s3c_fb_driverdata s3c_fb_data_s5pv210 = {
 		},
 
 		.has_shadowcon	= 1,
+		.has_blendcon	= 1,
 		.has_clksel	= 1,
 	},
 	.win[0]	= &s3c_fb_data_s5p_wins[0],
@@ -1860,6 +1875,7 @@ static struct s3c_fb_driverdata s3c_fb_data_exynos4 = {
 		},
 
 		.has_shadowcon	= 1,
+		.has_blendcon	= 1,
 	},
 	.win[0]	= &s3c_fb_data_s5p_wins[0],
 	.win[1]	= &s3c_fb_data_s5p_wins[1],
@@ -1923,6 +1939,8 @@ static struct s3c_fb_driverdata s3c_fb_data_s5p64x0 = {
 			[1] = 0x2800,
 			[2] = 0x2c00,
 		},
+
+		.has_blendcon	= 1,
 	},
 	.win[0] = &s3c_fb_data_s5p_wins[0],
 	.win[1] = &s3c_fb_data_s5p_wins[1],