[PATCH RFC 09/13] media: add a V4L2 OF parser

[Sylwester Nawrocki]

From: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>

Add a V4L2 OF parser, implementing bindings, documented in
Documentation/devicetree/bindings/media/v4l2.txt.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
---
 drivers/media/v4l2-core/Makefile  |    3 +
 drivers/media/v4l2-core/v4l2-of.c |  190 +++++++++++++++++++++++++++++++++++++
 include/media/v4l2-of.h           |   62 ++++++++++++
 3 files changed, 255 insertions(+)
 create mode 100644 drivers/media/v4l2-core/v4l2-of.c
 create mode 100644 include/media/v4l2-of.h

diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
index c2d61d4..00f64d6 100644
--- a/drivers/media/v4l2-core/Makefile
+++ b/drivers/media/v4l2-core/Makefile
@@ -9,6 +9,9 @@ videodev-objs	:=	v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o \
 ifeq ($(CONFIG_COMPAT),y)
   videodev-objs += v4l2-compat-ioctl32.o
 endif
+ifeq ($(CONFIG_OF),y)
+  videodev-objs += v4l2-of.o
+endif
 
 obj-$(CONFIG_VIDEO_DEV) += videodev.o v4l2-int-device.o
 obj-$(CONFIG_VIDEO_V4L2) += v4l2-common.o
diff --git a/drivers/media/v4l2-core/v4l2-of.c b/drivers/media/v4l2-core/v4l2-of.c
new file mode 100644
index 0000000..f45d64b
--- /dev/null
+++ b/drivers/media/v4l2-core/v4l2-of.c
@@ -0,0 +1,190 @@
+/*
+ * V4L2 OF binding parsing library
+ *
+ * Copyright (C) 2012 Renesas Electronics Corp.
+ * Author: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/types.h>
+
+#include <media/v4l2-of.h>
+
+/*
+ * All properties are optional. If none are found, we don't set any flags. This
+ * means, the port has a static configuration and no properties have to be
+ * specified explicitly.
+ * If any properties are found, that identify the bus as parallel, and
+ * slave-mode isn't set, we set V4L2_MBUS_MASTER. Similarly, if we recognise the
+ * bus as serial CSI-2 and clock-noncontinuous isn't set, we set the
+ * V4L2_MBUS_CSI2_CONTINUOUS_CLOCK flag.
+ * The caller should hold a reference to "node."
+ */
+void v4l2_of_parse_link(const struct device_node *node,
+			struct v4l2_of_link *link)
+{
+	const struct device_node *port_node = of_get_parent(node);
+	int size;
+	unsigned int v;
+	u32 data_lanes[ARRAY_SIZE(link->mipi_csi_2.data_lanes)];
+	bool data_lanes_present;
+
+	memset(link, 0, sizeof(*link));
+
+	link->local_node = node;
+
+	/* Doesn't matter, whether the below two calls succeed */
+	of_property_read_u32(port_node, "reg", &link->port);
+	of_property_read_u32(node, "reg", &link->addr);
+
+	if (!of_property_read_u32(node, "bus-width", &v))
+		link->parallel.bus_width = v;
+
+	if (!of_property_read_u32(node, "data-shift", &v))
+		link->parallel.data_shift = v;
+
+	if (!of_property_read_u32(node, "hsync-active", &v))
+		link->mbus_flags |= v ? V4L2_MBUS_HSYNC_ACTIVE_HIGH :
+			V4L2_MBUS_HSYNC_ACTIVE_LOW;
+
+	if (!of_property_read_u32(node, "vsync-active", &v))
+		link->mbus_flags |= v ? V4L2_MBUS_VSYNC_ACTIVE_HIGH :
+			V4L2_MBUS_VSYNC_ACTIVE_LOW;
+
+	if (!of_property_read_u32(node, "data-active", &v))
+		link->mbus_flags |= v ? V4L2_MBUS_DATA_ACTIVE_HIGH :
+			V4L2_MBUS_DATA_ACTIVE_LOW;
+
+	if (!of_property_read_u32(node, "pclk-sample", &v))
+		link->mbus_flags |= v ? V4L2_MBUS_PCLK_SAMPLE_RISING :
+			V4L2_MBUS_PCLK_SAMPLE_FALLING;
+
+	if (!of_property_read_u32(node, "field-even-active", &v))
+		link->mbus_flags |= v ? V4L2_MBUS_FIELD_EVEN_HIGH :
+			V4L2_MBUS_FIELD_EVEN_LOW;
+
+	if (of_get_property(node, "slave-mode", &size))
+		link->mbus_flags |= V4L2_MBUS_SLAVE;
+
+	/* If any parallel-bus properties have been found, skip serial ones */
+	if (link->parallel.bus_width || link->parallel.data_shift ||
+	    link->mbus_flags) {
+		/* Default parallel bus-master */
+		if (!(link->mbus_flags & V4L2_MBUS_SLAVE))
+			link->mbus_flags |= V4L2_MBUS_MASTER;
+		return;
+	}
+
+	if (!of_property_read_u32(node, "clock-lanes", &v))
+		link->mipi_csi_2.clock_lane = v;
+
+	if (!of_property_read_u32_array(node, "data-lanes", data_lanes,
+					ARRAY_SIZE(data_lanes))) {
+		int i;
+		for (i = 0; i < ARRAY_SIZE(data_lanes); i++)
+			link->mipi_csi_2.data_lanes[i] = data_lanes[i];
+		data_lanes_present = true;
+	} else {
+		data_lanes_present = false;
+	}
+
+	if (of_get_property(node, "clock-noncontinuous", &size))
+		link->mbus_flags |= V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK;
+
+	if ((link->mipi_csi_2.clock_lane || data_lanes_present) &&
+	    !(link->mbus_flags & V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK))
+		/* Default CSI-2: continuous clock */
+		link->mbus_flags |= V4L2_MBUS_CSI2_CONTINUOUS_CLOCK;
+}
+EXPORT_SYMBOL(v4l2_of_parse_link);
+
+/*
+ * Return a refcounted next "link" DT node. Contrary to the common OF practice,
+ * we do not drop the reference to previous, users have to do it themselves,
+ * when they're done with the node.
+ */
+struct device_node *v4l2_of_get_next_link(const struct device_node *parent,
+					struct device_node *previous)
+{
+	struct device_node *child, *port;
+
+	if (!parent)
+		return NULL;
+
+	if (!previous) {
+		/*
+		 * If this is the first call, we have to find a port within this
+		 * node
+		 */
+		for_each_child_of_node(parent, port) {
+			if (!of_node_cmp(port->name, "port"))
+				break;
+		}
+		if (port) {
+			/* Found a port, get a link */
+			child = of_get_next_child(port, NULL);
+			of_node_put(port);
+		} else {
+			child = NULL;
+		}
+		if (!child)
+			pr_err("%s(): Invalid DT: %s has no link children!\n",
+			       __func__, parent->name);
+	} else {
+		port = of_get_parent(previous);
+		if (!port)
+			/* Hm, has someone given us the root node?... */
+			return NULL;
+
+		/* Avoid dropping previous refcount to 0 */
+		of_node_get(previous);
+		child = of_get_next_child(port, previous);
+		if (child) {
+			of_node_put(port);
+			return child;
+		}
+
+		/* No more links under this port, try the next one */
+		do {
+			port = of_get_next_child(parent, port);
+			if (!port)
+				return NULL;
+		} while (of_node_cmp(port->name, "port"));
+
+		/* Pick up the first link on this port */
+		child = of_get_next_child(port, NULL);
+		of_node_put(port);
+	}
+
+	return child;
+}
+EXPORT_SYMBOL(v4l2_of_get_next_link);
+
+/* Return a refcounted DT node, owning the link, referenced by "remote" */
+struct device_node *v4l2_of_get_remote(const struct device_node *node)
+{
+	struct device_node *remote, *tmp;
+
+	/* Get remote link DT node */
+	remote = of_parse_phandle(node, "remote", 0);
+	if (!remote)
+		return NULL;
+
+	/* remote port */
+	tmp = of_get_parent(remote);
+	of_node_put(remote);
+	if (!tmp)
+		return NULL;
+
+	/* remote DT node */
+	remote = of_get_parent(tmp);
+	of_node_put(tmp);
+
+	return remote;
+}
+EXPORT_SYMBOL(v4l2_of_get_remote);
diff --git a/include/media/v4l2-of.h b/include/media/v4l2-of.h
new file mode 100644
index 0000000..6fafedb
--- /dev/null
+++ b/include/media/v4l2-of.h
@@ -0,0 +1,62 @@
+/*
+ * V4L2 OF binding parsing library
+ *
+ * Copyright (C) 2012 Renesas Electronics Corp.
+ * Author: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ */
+#ifndef _V4L2_OF_H
+#define _V4L2_OF_H
+
+#include <linux/list.h>
+#include <linux/types.h>
+
+#include <media/v4l2-mediabus.h>
+
+struct device_node;
+
+struct v4l2_of_link {
+	unsigned int port;
+	unsigned int addr;
+	struct list_head head;
+	const struct device_node *local_node;
+	const __be32 *remote;
+	unsigned int mbus_flags;
+	union {
+		struct {
+			unsigned char bus_width;
+			unsigned char data_shift;
+		} parallel;
+		struct {
+			unsigned char data_lanes[4];
+			unsigned char clock_lane;
+		} mipi_csi_2;
+	};
+};
+
+#ifdef CONFIG_OF
+void v4l2_of_parse_link(const struct device_node *node,
+			struct v4l2_of_link *link);
+struct device_node *v4l2_of_get_next_link(const struct device_node *parent,
+					struct device_node *previous);
+struct device_node *v4l2_of_get_remote(const struct device_node *node);
+#else
+static inline void v4l2_of_parse_link(const struct device_node *node,
+				      struct v4l2_of_link *link)
+{
+}
+static inline struct device_node *v4l2_of_get_next_link(const struct device_node *parent,
+						struct device_node *previous)
+{
+	return NULL;
+}
+static inline struct device_node *v4l2_of_get_remote(const struct device_node *node)
+{
+	return NULL;
+}
+#endif
+
+#endif
-- 
1.7.9.5

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