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Subject[PATCH v2 3/5] drm: of: add display bus-format parser
Date
Add a common API to parse display bus format strings into fourcc codes.

Signed-off-by: Peter Rosin <peda@axentia.se>
---
.../devicetree/bindings/display/bus-format.txt | 35 +++++++++++++
drivers/gpu/drm/drm_of.c | 59 ++++++++++++++++++++++
include/drm/drm_of.h | 9 ++++
3 files changed, 103 insertions(+)
create mode 100644 Documentation/devicetree/bindings/display/bus-format.txt

diff --git a/Documentation/devicetree/bindings/display/bus-format.txt b/Documentation/devicetree/bindings/display/bus-format.txt
new file mode 100644
index 000000000000..590e6c73f3dc
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/bus-format.txt
@@ -0,0 +1,35 @@
+Bus formats in the display pipe
+===============================
+
+Various encoders in display controllers output the pixels in different
+formats. Circuits handling display connectors and hardwired panels also
+expect pixel input in various formats. We call these formats bus formats.
+
+Some bus formats are:
+
+Parallel
+--------
+
+rgb888
+ 8 parallel lines for red, green and blue respectively. There are
+ also lines for the pixel-clock, horizontal-sync, vertical-sync
+ and data-enable.
+
+rgb666
+ Same as rgb888, but with 6 lines per color.
+
+rgb565
+ Same as rgb888, but with 6 green lines and 5 red and blue lines.
+
+rgb444
+ Same as rgb888, but with 4 lines per color.
+
+
+LVDS
+----
+
+jeida-18
+jeida-24
+vesa-24
+ These are LVDS bus formats, see the data-mapping property in
+ panel/panel-lvds.txt for a description of these bus formats.
diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index 4c191c050e7d..5f65471225bb 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -262,3 +262,62 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
return ret;
}
EXPORT_SYMBOL_GPL(drm_of_find_panel_or_bridge);
+
+/*
+ * drm_of_bus_formats - parse list of bus format strings into drm fourcc
+ * @np: device tree node containing bus format property
+ * @propname: name of bus format property
+ * @bus_formats: array of parsed fourcc codes
+ *
+ * On success, @bus_formats points to a location where the actual drm
+ * fourcc codes are.
+ * WARNING: The caller is responsible for freeing this memory with kfree.
+ *
+ * Returns the number of parsed bus format entries, or one of the standard
+ * error codes on failure.
+ */
+int drm_of_bus_formats(const struct device_node *np, const char *propname,
+ u32 **bus_formats)
+{
+ int num_bus_formats = of_property_count_strings(np, propname);
+ const char *fmt;
+ int ret;
+ int i;
+
+ if (num_bus_formats <= 0)
+ return num_bus_formats;
+
+ *bus_formats = kmalloc(num_bus_formats * sizeof(**bus_formats),
+ GFP_KERNEL);
+ if (!*bus_formats)
+ return -ENOMEM;
+
+ for (i = 0; i < num_bus_formats; ++i) {
+ ret = of_property_read_string_index(np, propname, i, &fmt);
+ if (ret < 0)
+ return ret;
+
+ if (!strcmp(fmt, "rgb444")) {
+ *bus_formats[i] = MEDIA_BUS_FMT_RGB444_1X12;
+ } else if (!strcmp(fmt, "rgb565")) {
+ *bus_formats[i] = MEDIA_BUS_FMT_RGB565_1X16;
+ } else if (!strcmp(fmt, "rgb666")) {
+ *bus_formats[i] = MEDIA_BUS_FMT_RGB666_1X18;
+ } else if (!strcmp(fmt, "rgb888")) {
+ *bus_formats[i] = MEDIA_BUS_FMT_RGB888_1X24;
+ } else if (!strcmp(fmt, "jeida-18")) {
+ *bus_formats[i] = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG;
+ } else if (!strcmp(fmt, "jeida-24")) {
+ *bus_formats[i] = MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA;
+ } else if (!strcmp(fmt, "vesa-24")) {
+ *bus_formats[i] = MEDIA_BUS_FMT_RGB888_1X7X4_SPWG;
+ } else {
+ kfree(*bus_formats);
+ *bus_formats = NULL;
+ return -EINVAL;
+ }
+ }
+
+ return num_bus_formats;
+}
+EXPORT_SYMBOL_GPL(drm_of_bus_formats);
diff --git a/include/drm/drm_of.h b/include/drm/drm_of.h
index b93c239afb60..ccacddc03a2e 100644
--- a/include/drm/drm_of.h
+++ b/include/drm/drm_of.h
@@ -33,6 +33,8 @@ 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_bus_formats(const struct device_node *np, const char *propname,
+ u32 **bus_formats);
#else
static inline uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
struct device_node *port)
@@ -69,6 +71,13 @@ static inline int drm_of_find_panel_or_bridge(const struct device_node *np,
{
return -EINVAL;
}
+
+static inline int drm_of_bus_formats(const struct device_node *np,
+ const char *propname,
+ u32 **bus_formats)
+{
+ return -EINVAL;
+}
#endif

/*
--
2.11.0
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