drm: exynos: Add driver for HDMI audio interface

The hdmi-codec interface added in this patch is required to properly
support HDMI audio. Currently the audio part of the SoC internal
HDMI transmitter is configured with fixed values, which makes HDMI
audio working by chance, only on boards having an external audio
codec connected in parallel with the HDMI audio transmitter's input
I2S interface.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/Kconfig

@@ -3,6 +3,7 @@ config DRM_EXYNOS
 	depends on OF && DRM && (ARCH_S3C64XX || ARCH_EXYNOS || ARCH_MULTIPLATFORM)
 	select DRM_KMS_HELPER
 	select VIDEOMODE_HELPERS
+	select SND_SOC_HDMI_CODEC if SND_SOC
 	help
 	  Choose this option if you have a Samsung SoC EXYNOS chipset.
 	  If M is selected the module will be called exynosdrm.

drivers/gpu/drm/exynos/regs-hdmi.h

@@ -419,11 +419,9 @@
 #define HDMI_I2S_DSD_CON		HDMI_I2S_BASE(0x01c)
 #define HDMI_I2S_MUX_CON		HDMI_I2S_BASE(0x020)
 #define HDMI_I2S_CH_ST_CON		HDMI_I2S_BASE(0x024)
-#define HDMI_I2S_CH_ST_0		HDMI_I2S_BASE(0x028)
-#define HDMI_I2S_CH_ST_1		HDMI_I2S_BASE(0x02c)
-#define HDMI_I2S_CH_ST_2		HDMI_I2S_BASE(0x030)
-#define HDMI_I2S_CH_ST_3		HDMI_I2S_BASE(0x034)
-#define HDMI_I2S_CH_ST_4		HDMI_I2S_BASE(0x038)
+/* n must be within range 0...(HDMI_I2S_CH_ST_MAXNUM - 1) */
+#define HDMI_I2S_CH_ST_MAXNUM		5
+#define HDMI_I2S_CH_ST(n)		HDMI_I2S_BASE(0x028 + 4 * (n))
 #define HDMI_I2S_CH_ST_SH_0		HDMI_I2S_BASE(0x03c)
 #define HDMI_I2S_CH_ST_SH_1		HDMI_I2S_BASE(0x040)
 #define HDMI_I2S_CH_ST_SH_2		HDMI_I2S_BASE(0x044)