video: add of helper for display timings/videomode

This adds support for reading display timings from DT into a struct
display_timings. The of_display_timing implementation supports multiple
subnodes. All children are read into an array, that can be queried.

If no native mode is specified, the first subnode will be used.

For cases where the graphics driver knows there can be only one
mode description or where the driver only supports one mode, a helper
function of_get_videomode is added, that gets a struct videomode from DT.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Thierry Reding <thierry.reding@avionic-design.de>
Acked-by: Thierry Reding <thierry.reding@avionic-design.de>
Tested-by: Thierry Reding <thierry.reding@avionic-design.de>
Tested-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Afzal Mohammed <Afzal@ti.com>
Tested-by: Rob Clark <robclark@gmail.com>
Tested-by: Leela Krishna Amudala <leelakrishna.a@gmail.com>

1 files changed, 239 insertions, 0 deletions

diff --git a/drivers/video/of_display_timing.c b/drivers/video/of_display_timing.c
new file mode 100644
index 000000000000..13ecd9897010
--- /dev/null
+++ b/drivers/video/of_display_timing.c
@@ -0,0 +1,239 @@
+/*
+ * OF helpers for parsing display timings
+ *
+ * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>, Pengutronix
+ *
+ * based on of_videomode.c by Sascha Hauer <s.hauer@pengutronix.de>
+ *
+ * This file is released under the GPLv2
+ */
+#include <linux/export.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <video/display_timing.h>
+#include <video/of_display_timing.h>
+
+/**
+ * parse_timing_property - parse timing_entry from device_node
+ * @np: device_node with the property
+ * @name: name of the property
+ * @result: will be set to the return value
+ *
+ * DESCRIPTION:
+ * Every display_timing can be specified with either just the typical value or
+ * a range consisting of min/typ/max. This function helps handling this
+ **/
+static int parse_timing_property(struct device_node *np, const char *name,
+			  struct timing_entry *result)
+{
+	struct property *prop;
+	int length, cells, ret;
+
+	prop = of_find_property(np, name, &length);
+	if (!prop) {
+		pr_err("%s: could not find property %s\n",
+			of_node_full_name(np), name);
+		return -EINVAL;
+	}
+
+	cells = length / sizeof(u32);
+	if (cells == 1) {
+		ret = of_property_read_u32(np, name, &result->typ);
+		result->min = result->typ;
+		result->max = result->typ;
+	} else if (cells == 3) {
+		ret = of_property_read_u32_array(np, name, &result->min, cells);
+	} else {
+		pr_err("%s: illegal timing specification in %s\n",
+			of_node_full_name(np), name);
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+/**
+ * of_get_display_timing - parse display_timing entry from device_node
+ * @np: device_node with the properties
+ **/
+static struct display_timing *of_get_display_timing(struct device_node *np)
+{
+	struct display_timing *dt;
+	u32 val = 0;
+	int ret = 0;
+
+	dt = kzalloc(sizeof(*dt), GFP_KERNEL);
+	if (!dt) {
+		pr_err("%s: could not allocate display_timing struct\n",
+			of_node_full_name(np));
+		return NULL;
+	}
+
+	ret |= parse_timing_property(np, "hback-porch", &dt->hback_porch);
+	ret |= parse_timing_property(np, "hfront-porch", &dt->hfront_porch);
+	ret |= parse_timing_property(np, "hactive", &dt->hactive);
+	ret |= parse_timing_property(np, "hsync-len", &dt->hsync_len);
+	ret |= parse_timing_property(np, "vback-porch", &dt->vback_porch);
+	ret |= parse_timing_property(np, "vfront-porch", &dt->vfront_porch);
+	ret |= parse_timing_property(np, "vactive", &dt->vactive);
+	ret |= parse_timing_property(np, "vsync-len", &dt->vsync_len);
+	ret |= parse_timing_property(np, "clock-frequency", &dt->pixelclock);
+
+	dt->dmt_flags = 0;
+	dt->data_flags = 0;
+	if (!of_property_read_u32(np, "vsync-active", &val))
+		dt->dmt_flags |= val ? VESA_DMT_VSYNC_HIGH :
+				VESA_DMT_VSYNC_LOW;
+	if (!of_property_read_u32(np, "hsync-active", &val))
+		dt->dmt_flags |= val ? VESA_DMT_HSYNC_HIGH :
+				VESA_DMT_HSYNC_LOW;
+	if (!of_property_read_u32(np, "de-active", &val))
+		dt->data_flags |= val ? DISPLAY_FLAGS_DE_HIGH :
+				DISPLAY_FLAGS_DE_LOW;
+	if (!of_property_read_u32(np, "pixelclk-active", &val))
+		dt->data_flags |= val ? DISPLAY_FLAGS_PIXDATA_POSEDGE :
+				DISPLAY_FLAGS_PIXDATA_NEGEDGE;
+
+	if (of_property_read_bool(np, "interlaced"))
+		dt->data_flags |= DISPLAY_FLAGS_INTERLACED;
+	if (of_property_read_bool(np, "doublescan"))
+		dt->data_flags |= DISPLAY_FLAGS_DOUBLESCAN;
+
+	if (ret) {
+		pr_err("%s: error reading timing properties\n",
+			of_node_full_name(np));
+		kfree(dt);
+		return NULL;
+	}
+
+	return dt;
+}
+
+/**
+ * of_get_display_timings - parse all display_timing entries from a device_node
+ * @np: device_node with the subnodes
+ **/
+struct display_timings *of_get_display_timings(struct device_node *np)
+{
+	struct device_node *timings_np;
+	struct device_node *entry;
+	struct device_node *native_mode;
+	struct display_timings *disp;
+
+	if (!np) {
+		pr_err("%s: no devicenode given\n", of_node_full_name(np));
+		return NULL;
+	}
+
+	timings_np = of_find_node_by_name(np, "display-timings");
+	if (!timings_np) {
+		pr_err("%s: could not find display-timings node\n",
+			of_node_full_name(np));
+		return NULL;
+	}
+
+	disp = kzalloc(sizeof(*disp), GFP_KERNEL);
+	if (!disp) {
+		pr_err("%s: could not allocate struct disp'\n",
+			of_node_full_name(np));
+		goto dispfail;
+	}
+
+	entry = of_parse_phandle(timings_np, "native-mode", 0);
+	/* assume first child as native mode if none provided */
+	if (!entry)
+		entry = of_get_next_child(np, NULL);
+	/* if there is no child, it is useless to go on */
+	if (!entry) {
+		pr_err("%s: no timing specifications given\n",
+			of_node_full_name(np));
+		goto entryfail;
+	}
+
+	pr_debug("%s: using %s as default timing\n",
+		of_node_full_name(np), entry->name);
+
+	native_mode = entry;
+
+	disp->num_timings = of_get_child_count(timings_np);
+	if (disp->num_timings == 0) {
+		/* should never happen, as entry was already found above */
+		pr_err("%s: no timings specified\n", of_node_full_name(np));
+		goto entryfail;
+	}
+
+	disp->timings = kzalloc(sizeof(struct display_timing *) *
+				disp->num_timings, GFP_KERNEL);
+	if (!disp->timings) {
+		pr_err("%s: could not allocate timings array\n",
+			of_node_full_name(np));
+		goto entryfail;
+	}
+
+	disp->num_timings = 0;
+	disp->native_mode = 0;
+
+	for_each_child_of_node(timings_np, entry) {
+		struct display_timing *dt;
+
+		dt = of_get_display_timing(entry);
+		if (!dt) {
+			/*
+			 * to not encourage wrong devicetrees, fail in case of
+			 * an error
+			 */
+			pr_err("%s: error in timing %d\n",
+				of_node_full_name(np), disp->num_timings + 1);
+			goto timingfail;
+		}
+
+		if (native_mode == entry)
+			disp->native_mode = disp->num_timings;
+
+		disp->timings[disp->num_timings] = dt;
+		disp->num_timings++;
+	}
+	of_node_put(timings_np);
+	/*
+	 * native_mode points to the device_node returned by of_parse_phandle
+	 * therefore call of_node_put on it
+	 */
+	of_node_put(native_mode);
+
+	pr_debug("%s: got %d timings. Using timing #%d as default\n",
+		of_node_full_name(np), disp->num_timings,
+		disp->native_mode + 1);
+
+	return disp;
+
+timingfail:
+	if (native_mode)
+		of_node_put(native_mode);
+	display_timings_release(disp);
+entryfail:
+	kfree(disp);
+dispfail:
+	of_node_put(timings_np);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(of_get_display_timings);
+
+/**
+ * of_display_timings_exist - check if a display-timings node is provided
+ * @np: device_node with the timing
+ **/
+int of_display_timings_exist(struct device_node *np)
+{
+	struct device_node *timings_np;
+
+	if (!np)
+		return -EINVAL;
+
+	timings_np = of_parse_phandle(np, "display-timings", 0);
+	if (!timings_np)
+		return -EINVAL;
+
+	of_node_put(timings_np);
+	return 1;
+}
+EXPORT_SYMBOL_GPL(of_display_timings_exist);