[PATCH v1 2/9] drm: add drm specific media-bus-format header file

[Sam Ravnborg]

For now the header file includes a single method to retreive the bpc
from the bus format.
The supported MEDIA_BUS_* codes are the ones used for the current panels
in DRM. The list can be extended as there are a need for more formats.

Signed-off-by: Sam Ravnborg <sam at ravnborg.org>
---
 include/drm/media-bus-format.h | 53 ++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 include/drm/media-bus-format.h

diff --git a/include/drm/media-bus-format.h b/include/drm/media-bus-format.h
new file mode 100644
index 000000000000..d4d18f19a70f
--- /dev/null
+++ b/include/drm/media-bus-format.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2022 Sam Ravnborg
+ */
+
+#ifndef __LINUX_DRM_MEDIA_BUS_FORMAT
+#define __LINUX_DRM_MEDIA_BUS_FORMAT
+
+#include <linux/bug.h>
+#include <linux/media-bus-format.h>
+#include <linux/types.h>
+
+/**
+ * media_bus_format_to_bpc - The bits per color channel for the bus_format
+ *
+ * Based on the supplied bus_format return the maximum number of bits
+ * per color channel.
+ *
+ * RETURNS
+ * The number of bits per color channel, or -EINVAL if the bus_format
+ * is unknown.
+ */
+static inline int media_bus_format_to_bpc(u32 bus_format)
+{
+	switch (bus_format) {
+	/* DPI */
+	case MEDIA_BUS_FMT_RGB565_1X16:
+	case MEDIA_BUS_FMT_RGB666_1X18:
+		return 6;
+
+	/* DPI */
+	case MEDIA_BUS_FMT_RGB888_1X24:
+	case MEDIA_BUS_FMT_RGB888_3X8:
+	case MEDIA_BUS_FMT_RGB888_3X8_DELTA:
+	case MEDIA_BUS_FMT_Y8_1X8:
+		return 8;
+
+     	/* LVDS */
+	case MEDIA_BUS_FMT_RGB666_1X7X3_SPWG:
+		return 6;
+
+     	/* LVDS */
+	case MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA:
+	case MEDIA_BUS_FMT_RGB888_1X7X4_SPWG:
+		return 8;
+
+	default:
+		WARN(1, "Unknown MEDIA_BUS format %d\n", bus_format);
+		return -EINVAL;
+	}
+}
+
+#endif
-- 
2.32.0