video: dw_hdmi: support SoC specific read/write ops

Some IPs like the meson VPU have a specific way to write to dw_hdmi
registers. Make it configurable.

Signed-off-by: Jorge Ramirez-Ortiz <jramirez@baylibre.com>
[added commit description]
Signed-off-by: Maxime Jourdan <mjourdan@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Anatolij Gustschin <agust@denx.de>
diff --git a/drivers/video/dw_hdmi.c b/drivers/video/dw_hdmi.c
index 229bd63..e03f24f 100644
--- a/drivers/video/dw_hdmi.c
+++ b/drivers/video/dw_hdmi.c
@@ -52,7 +52,7 @@
 	}
 };
 
-static void hdmi_write(struct dw_hdmi *hdmi, u8 val, int offset)
+static void dw_hdmi_write(struct dw_hdmi *hdmi, u8 val, int offset)
 {
 	switch (hdmi->reg_io_width) {
 	case 1:
@@ -67,7 +67,7 @@
 	}
 }
 
-static u8 hdmi_read(struct dw_hdmi *hdmi, int offset)
+static u8 dw_hdmi_read(struct dw_hdmi *hdmi, int offset)
 {
 	switch (hdmi->reg_io_width) {
 	case 1:
@@ -82,6 +82,10 @@
 	return 0;
 }
 
+static u8 (*hdmi_read)(struct dw_hdmi *hdmi, int offset) = dw_hdmi_read;
+static void (*hdmi_write)(struct dw_hdmi *hdmi, u8 val, int offset) =
+								 dw_hdmi_write;
+
 static void hdmi_mod(struct dw_hdmi *hdmi, unsigned reg, u8 mask, u8 data)
 {
 	u8 val = hdmi_read(hdmi, reg) & ~mask;
@@ -754,6 +758,12 @@
 		  HDMI_IH_MUTE_MUTE_WAKEUP_INTERRUPT |
 		  HDMI_IH_MUTE_MUTE_ALL_INTERRUPT;
 
+	if (hdmi->write_reg)
+		hdmi_write = hdmi->write_reg;
+
+	if (hdmi->read_reg)
+		hdmi_read = hdmi->read_reg;
+
 	hdmi_write(hdmi, ih_mute, HDMI_IH_MUTE);
 
 	/* enable i2c master done irq */