[PATCH 2/5] drm/of: Add drm_of_dpi_get_color_coding()

[Liu Ying <victor.liu@nxp.com>]

Add helper function drm_of_dpi_get_color_coding() to get media bus format
value from MIPI DPI color coding string.

Signed-off-by: Liu Ying <victor.liu@nxp.com>
---
 drivers/gpu/drm/drm_of.c | 43 ++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_of.h     |  7 +++++++
 2 files changed, 50 insertions(+)

diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index d0183dea7703..6e2e19275b99 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -285,6 +285,49 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
 }
 EXPORT_SYMBOL_GPL(drm_of_find_panel_or_bridge);
 
+/**
+ * drm_of_dpi_get_color_coding - Get DPI color coding
+ * @endpoint: DT endpoint node of the DPI source or sink
+ *
+ * Convert DT "dpi-color-coding" property string value into media bus format
+ * value.
+ *
+ * Return:
+ * * MEDIA_BUS_FMT_RGB565_1X16 - dpi-color-coding is "16bit-configuration1"
+ * * MEDIA_BUS_FMT_RGB565_1X24_CPADHI - dpi-color-coding is
+ *                                      "16bit-configuration2"
+ * * MEDIA_BUS_FMT_RGB666_1X18 - dpi-color-coding is "18bit-configuration1"
+ * * MEDIA_BUS_FMT_BGR666_1X24_CPADHI - dpi-color-coding is
+ *                                      "18bit-configuration2"
+ * * MEDIA_BUS_FMT_RGB888_1X24 - dpi-color-coding is "24bit"
+ * * -EINVAL - the "dpi-color-coding" property is unsupported
+ * * -ENODEV - the "dpi-color-coding" property is missing
+ */
+int drm_of_dpi_get_color_coding(const struct device_node *endpoint)
+{
+	const char *coding;
+	int ret;
+
+	ret = of_property_read_string(endpoint, "dpi-color-coding", &coding);
+	if (ret < 0)
+		return -ENODEV;
+
+	/* TODO: Add 16bit-configuration3 support. */
+	if (!strcmp(coding, "16bit-configuration1"))
+		return MEDIA_BUS_FMT_RGB565_1X16;
+	if (!strcmp(coding, "16bit-configuration2"))
+		return MEDIA_BUS_FMT_RGB565_1X24_CPADHI;
+	if (!strcmp(coding, "18bit-configuration1"))
+		return MEDIA_BUS_FMT_RGB666_1X18;
+	if (!strcmp(coding, "18bit-configuration2"))
+		return MEDIA_BUS_FMT_BGR666_1X24_CPADHI;
+	if (!strcmp(coding, "24bit"))
+		return MEDIA_BUS_FMT_RGB888_1X24;
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(drm_of_dpi_get_color_coding);
+
 enum drm_of_lvds_pixels {
 	DRM_OF_LVDS_EVEN = BIT(0),
 	DRM_OF_LVDS_ODD = BIT(1),
diff --git a/include/drm/drm_of.h b/include/drm/drm_of.h
index 7f0256dae3f1..0a827f3b3a55 100644
--- a/include/drm/drm_of.h
+++ b/include/drm/drm_of.h
@@ -50,6 +50,7 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
 				int port, int endpoint,
 				struct drm_panel **panel,
 				struct drm_bridge **bridge);
+int drm_of_dpi_get_color_coding(const struct device_node *endpoint);
 int drm_of_lvds_get_dual_link_pixel_order(const struct device_node *port1,
 					  const struct device_node *port2);
 int drm_of_lvds_get_dual_link_pixel_order_sink(struct device_node *port1,
@@ -104,6 +105,12 @@ static inline int drm_of_find_panel_or_bridge(const struct device_node *np,
 	return -EINVAL;
 }
 
+static inline int
+drm_of_dpi_get_color_coding(const struct device_node *endpoint)
+{
+	return -EINVAL;
+}
+
 static inline int
 drm_of_lvds_get_dual_link_pixel_order(const struct device_node *port1,
 				      const struct device_node *port2)
-- 
2.34.1