[media] v4l: fwnode: Support generic fwnode for parsing standardised properties

The fwnode_handle is a more generic way than OF device_node to describe
firmware nodes. Instead of the OF API, use more generic fwnode API to
obtain the same information.

As the V4L2 fwnode support will be required by a small minority of e.g.
ACPI based systems (the same might actually go for OF), make this a module
instead of embedding it in the videodev module.

The origins of the V4L2 fwnode framework is in the V4L2 OF framework.

Signed-off-by: Sakari Ailus <[e-mail]>
Tested-by: Hans Verkuil <[e-mail]>
Tested-by: Philipp Zabel <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/v4l2-core/Kconfig

···
 
 	  When in doubt, say N.
 
+config V4L2_FWNODE
+	tristate
+
 # Used by drivers that need Videobuf modules
 config VIDEOBUF_GEN
 	tristate

drivers/media/v4l2-core/Makefile

···
 ifeq ($(CONFIG_OF),y)
   videodev-objs += v4l2-of.o
 endif
+obj-$(CONFIG_V4L2_FWNODE) += v4l2-fwnode.o
 ifeq ($(CONFIG_TRACEPOINTS),y)
   videodev-objs += vb2-trace.o v4l2-trace.o
 endif

drivers/media/v4l2-core/v4l2-fwnode.c

···
+/*
+ * V4L2 fwnode binding parsing library
+ *
+ * The origins of the V4L2 fwnode library are in V4L2 OF library that
+ * formerly was located in v4l2-of.c.
+ *
+ * Copyright (c) 2016 Intel Corporation.
+ * Author: Sakari Ailus <[e-mail]>
+ *
+ * Copyright (C) 2012 - 2013 Samsung Electronics Co., Ltd.
+ * Author: Sylwester Nawrocki <[e-mail]>
+ *
+ * Copyright (C) 2012 Renesas Electronics Corp.
+ * Author: Guennadi Liakhovetski <[e-mail]>
+ *
+ * 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/acpi.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+#include <media/v4l2-fwnode.h>
+
+static int v4l2_fwnode_endpoint_parse_csi_bus(struct fwnode_handle *fwnode,
+					      struct v4l2_fwnode_endpoint *vep)
+{
+	struct v4l2_fwnode_bus_mipi_csi2 *bus = &vep->bus.mipi_csi2;
+	bool have_clk_lane = false;
+	unsigned int flags = 0, lanes_used = 0;
+	unsigned int i;
+	u32 v;
+	int rval;
+
+	rval = fwnode_property_read_u32_array(fwnode, "data-lanes", NULL, 0);
+	if (rval > 0) {
+		u32 array[ARRAY_SIZE(bus->data_lanes)];
+
+		bus->num_data_lanes =
+			min_t(int, ARRAY_SIZE(bus->data_lanes), rval);
+
+		fwnode_property_read_u32_array(fwnode, "data-lanes", array,
+					       bus->num_data_lanes);
+
+		for (i = 0; i < bus->num_data_lanes; i++) {
+			if (lanes_used & BIT(array[i]))
+				pr_warn("duplicated lane %u in data-lanes\n",
+					array[i]);
+			lanes_used |= BIT(array[i]);
+
+			bus->data_lanes[i] = array[i];
+		}
+	}
+
+	rval = fwnode_property_read_u32_array(fwnode, "lane-polarities", NULL,
+					      0);
+	if (rval > 0) {
+		u32 array[ARRAY_SIZE(bus->lane_polarities)];
+
+		if (rval < 1 + bus->num_data_lanes /* clock + data */) {
+			pr_warn("too few lane-polarities entries (need %u, got %u)\n",
+				1 + bus->num_data_lanes, rval);
+			return -EINVAL;
+		}
+
+		fwnode_property_read_u32_array(fwnode, "lane-polarities", array,
+					       1 + bus->num_data_lanes);
+
+		for (i = 0; i < 1 + bus->num_data_lanes; i++)
+			bus->lane_polarities[i] = array[i];
+	}
+
+	if (!fwnode_property_read_u32(fwnode, "clock-lanes", &v)) {
+		if (lanes_used & BIT(v))
+			pr_warn("duplicated lane %u in clock-lanes\n", v);
+		lanes_used |= BIT(v);
+
+		bus->clock_lane = v;
+		have_clk_lane = true;
+	}
+
+	if (fwnode_property_present(fwnode, "clock-noncontinuous"))
+		flags |= V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK;
+	else if (have_clk_lane || bus->num_data_lanes > 0)
+		flags |= V4L2_MBUS_CSI2_CONTINUOUS_CLOCK;
+
+	bus->flags = flags;
+	vep->bus_type = V4L2_MBUS_CSI2;
+
+	return 0;
+}
+
+static void v4l2_fwnode_endpoint_parse_parallel_bus(
+	struct fwnode_handle *fwnode, struct v4l2_fwnode_endpoint *vep)
+{
+	struct v4l2_fwnode_bus_parallel *bus = &vep->bus.parallel;
+	unsigned int flags = 0;
+	u32 v;
+
+	if (!fwnode_property_read_u32(fwnode, "hsync-active", &v))
+		flags |= v ? V4L2_MBUS_HSYNC_ACTIVE_HIGH :
+			V4L2_MBUS_HSYNC_ACTIVE_LOW;
+
+	if (!fwnode_property_read_u32(fwnode, "vsync-active", &v))
+		flags |= v ? V4L2_MBUS_VSYNC_ACTIVE_HIGH :
+			V4L2_MBUS_VSYNC_ACTIVE_LOW;
+
+	if (!fwnode_property_read_u32(fwnode, "field-even-active", &v))
+		flags |= v ? V4L2_MBUS_FIELD_EVEN_HIGH :
+			V4L2_MBUS_FIELD_EVEN_LOW;
+	if (flags)
+		vep->bus_type = V4L2_MBUS_PARALLEL;
+	else
+		vep->bus_type = V4L2_MBUS_BT656;
+
+	if (!fwnode_property_read_u32(fwnode, "pclk-sample", &v))
+		flags |= v ? V4L2_MBUS_PCLK_SAMPLE_RISING :
+			V4L2_MBUS_PCLK_SAMPLE_FALLING;
+
+	if (!fwnode_property_read_u32(fwnode, "data-active", &v))
+		flags |= v ? V4L2_MBUS_DATA_ACTIVE_HIGH :
+			V4L2_MBUS_DATA_ACTIVE_LOW;
+
+	if (fwnode_property_present(fwnode, "slave-mode"))
+		flags |= V4L2_MBUS_SLAVE;
+	else
+		flags |= V4L2_MBUS_MASTER;
+
+	if (!fwnode_property_read_u32(fwnode, "bus-width", &v))
+		bus->bus_width = v;
+
+	if (!fwnode_property_read_u32(fwnode, "data-shift", &v))
+		bus->data_shift = v;
+
+	if (!fwnode_property_read_u32(fwnode, "sync-on-green-active", &v))
+		flags |= v ? V4L2_MBUS_VIDEO_SOG_ACTIVE_HIGH :
+			V4L2_MBUS_VIDEO_SOG_ACTIVE_LOW;
+
+	bus->flags = flags;
+
+}
+
+/**
+ * v4l2_fwnode_endpoint_parse() - parse all fwnode node properties
+ * @fwnode: pointer to the endpoint's fwnode handle
+ * @vep: pointer to the V4L2 fwnode data structure
+ *
+ * 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 that identify the bus as parallel
+ * are found 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 @fwnode.
+ *
+ * NOTE: This function does not parse properties the size of which is variable
+ * without a low fixed limit. Please use v4l2_fwnode_endpoint_alloc_parse() in
+ * new drivers instead.
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int v4l2_fwnode_endpoint_parse(struct fwnode_handle *fwnode,
+			       struct v4l2_fwnode_endpoint *vep)
+{
+	int rval;
+
+	fwnode_graph_parse_endpoint(fwnode, &vep->base);
+
+	/* Zero fields from bus_type to until the end */
+	memset(&vep->bus_type, 0, sizeof(*vep) -
+	       offsetof(typeof(*vep), bus_type));
+
+	rval = v4l2_fwnode_endpoint_parse_csi_bus(fwnode, vep);
+	if (rval)
+		return rval;
+	/*
+	 * Parse the parallel video bus properties only if none
+	 * of the MIPI CSI-2 specific properties were found.
+	 */
+	if (vep->bus.mipi_csi2.flags == 0)
+		v4l2_fwnode_endpoint_parse_parallel_bus(fwnode, vep);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_fwnode_endpoint_parse);
+
+/*
+ * v4l2_fwnode_endpoint_free() - free the V4L2 fwnode acquired by
+ * v4l2_fwnode_endpoint_alloc_parse()
+ * @vep - the V4L2 fwnode the resources of which are to be released
+ *
+ * It is safe to call this function with NULL argument or on a V4L2 fwnode the
+ * parsing of which failed.
+ */
+void v4l2_fwnode_endpoint_free(struct v4l2_fwnode_endpoint *vep)
+{
+	if (IS_ERR_OR_NULL(vep))
+		return;
+
+	kfree(vep->link_frequencies);
+	kfree(vep);
+}
+EXPORT_SYMBOL_GPL(v4l2_fwnode_endpoint_free);
+
+/**
+ * v4l2_fwnode_endpoint_alloc_parse() - parse all fwnode node properties
+ * @fwnode: pointer to the endpoint's fwnode handle
+ *
+ * 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 that identify the bus as parallel
+ * are found 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 @fwnode.
+ *
+ * v4l2_fwnode_endpoint_alloc_parse() has two important differences to
+ * v4l2_fwnode_endpoint_parse():
+ *
+ * 1. It also parses variable size data.
+ *
+ * 2. The memory it has allocated to store the variable size data must be freed
+ *    using v4l2_fwnode_endpoint_free() when no longer needed.
+ *
+ * Return: Pointer to v4l2_fwnode_endpoint if successful, on an error pointer
+ * on error.
+ */
+struct v4l2_fwnode_endpoint *v4l2_fwnode_endpoint_alloc_parse(
+	struct fwnode_handle *fwnode)
+{
+	struct v4l2_fwnode_endpoint *vep;
+	int rval;
+
+	vep = kzalloc(sizeof(*vep), GFP_KERNEL);
+	if (!vep)
+		return ERR_PTR(-ENOMEM);
+
+	rval = v4l2_fwnode_endpoint_parse(fwnode, vep);
+	if (rval < 0)
+		goto out_err;
+
+	rval = fwnode_property_read_u64_array(fwnode, "link-frequencies",
+					      NULL, 0);
+	if (rval < 0)
+		goto out_err;
+
+	vep->link_frequencies =
+		kmalloc_array(rval, sizeof(*vep->link_frequencies), GFP_KERNEL);
+	if (!vep->link_frequencies) {
+		rval = -ENOMEM;
+		goto out_err;
+	}
+
+	vep->nr_of_link_frequencies = rval;
+
+	rval = fwnode_property_read_u64_array(fwnode, "link-frequencies",
+					      vep->link_frequencies,
+					      vep->nr_of_link_frequencies);
+	if (rval < 0)
+		goto out_err;
+
+	return vep;
+
+out_err:
+	v4l2_fwnode_endpoint_free(vep);
+	return ERR_PTR(rval);
+}
+EXPORT_SYMBOL_GPL(v4l2_fwnode_endpoint_alloc_parse);
+
+/**
+ * v4l2_fwnode_endpoint_parse_link() - parse a link between two endpoints
+ * @__fwnode: pointer to the endpoint's fwnode at the local end of the link
+ * @link: pointer to the V4L2 fwnode link data structure
+ *
+ * Fill the link structure with the local and remote nodes and port numbers.
+ * The local_node and remote_node fields are set to point to the local and
+ * remote port's parent nodes respectively (the port parent node being the
+ * parent node of the port node if that node isn't a 'ports' node, or the
+ * grand-parent node of the port node otherwise).
+ *
+ * A reference is taken to both the local and remote nodes, the caller must use
+ * v4l2_fwnode_endpoint_put_link() to drop the references when done with the
+ * link.
+ *
+ * Return: 0 on success, or -ENOLINK if the remote endpoint fwnode can't be
+ * found.
+ */
+int v4l2_fwnode_parse_link(struct fwnode_handle *__fwnode,
+			   struct v4l2_fwnode_link *link)
+{
+	const char *port_prop = is_of_node(__fwnode) ? "reg" : "port";
+	struct fwnode_handle *fwnode;
+
+	memset(link, 0, sizeof(*link));
+
+	fwnode = fwnode_get_parent(__fwnode);
+	fwnode_property_read_u32(fwnode, port_prop, &link->local_port);
+	fwnode = fwnode_get_next_parent(fwnode);
+	if (is_of_node(fwnode) &&
+	    of_node_cmp(to_of_node(fwnode)->name, "ports") == 0)
+		fwnode = fwnode_get_next_parent(fwnode);
+	link->local_node = fwnode;
+
+	fwnode = fwnode_graph_get_remote_endpoint(__fwnode);
+	if (!fwnode) {
+		fwnode_handle_put(fwnode);
+		return -ENOLINK;
+	}
+
+	fwnode = fwnode_get_parent(fwnode);
+	fwnode_property_read_u32(fwnode, port_prop, &link->remote_port);
+	fwnode = fwnode_get_next_parent(fwnode);
+	if (is_of_node(fwnode) &&
+	    of_node_cmp(to_of_node(fwnode)->name, "ports") == 0)
+		fwnode = fwnode_get_next_parent(fwnode);
+	link->remote_node = fwnode;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_fwnode_parse_link);
+
+/**
+ * v4l2_fwnode_put_link() - drop references to nodes in a link
+ * @link: pointer to the V4L2 fwnode link data structure
+ *
+ * Drop references to the local and remote nodes in the link. This function
+ * must be called on every link parsed with v4l2_fwnode_parse_link().
+ */
+void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link)
+{
+	fwnode_handle_put(link->local_node);
+	fwnode_handle_put(link->remote_node);
+}
+EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sakari Ailus <[e-mail]>");
+MODULE_AUTHOR("Sylwester Nawrocki <[e-mail]>");
+MODULE_AUTHOR("Guennadi Liakhovetski <[e-mail]>");

include/media/v4l2-fwnode.h

···
+/*
+ * V4L2 fwnode binding parsing library
+ *
+ * Copyright (c) 2016 Intel Corporation.
+ * Author: Sakari Ailus <[e-mail]>
+ *
+ * Copyright (C) 2012 - 2013 Samsung Electronics Co., Ltd.
+ * Author: Sylwester Nawrocki <[e-mail]>
+ *
+ * Copyright (C) 2012 Renesas Electronics Corp.
+ * Author: Guennadi Liakhovetski <[e-mail]>
+ *
+ * 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_FWNODE_H
+#define _V4L2_FWNODE_H
+
+#include <linux/errno.h>
+#include <linux/fwnode.h>
+#include <linux/list.h>
+#include <linux/types.h>
+
+#include <media/v4l2-mediabus.h>
+
+struct fwnode_handle;
+
+/**
+ * struct v4l2_fwnode_bus_mipi_csi2 - MIPI CSI-2 bus data structure
+ * @flags: media bus (V4L2_MBUS_*) flags
+ * @data_lanes: an array of physical data lane indexes
+ * @clock_lane: physical lane index of the clock lane
+ * @num_data_lanes: number of data lanes
+ * @lane_polarities: polarity of the lanes. The order is the same of
+ *		   the physical lanes.
+ */
+struct v4l2_fwnode_bus_mipi_csi2 {
+	unsigned int flags;
+	unsigned char data_lanes[4];
+	unsigned char clock_lane;
+	unsigned short num_data_lanes;
+	bool lane_polarities[5];
+};
+
+/**
+ * struct v4l2_fwnode_bus_parallel - parallel data bus data structure
+ * @flags: media bus (V4L2_MBUS_*) flags
+ * @bus_width: bus width in bits
+ * @data_shift: data shift in bits
+ */
+struct v4l2_fwnode_bus_parallel {
+	unsigned int flags;
+	unsigned char bus_width;
+	unsigned char data_shift;
+};
+
+/**
+ * struct v4l2_fwnode_endpoint - the endpoint data structure
+ * @base: fwnode endpoint of the v4l2_fwnode
+ * @bus_type: bus type
+ * @bus: bus configuration data structure
+ * @link_frequencies: array of supported link frequencies
+ * @nr_of_link_frequencies: number of elements in link_frequenccies array
+ */
+struct v4l2_fwnode_endpoint {
+	struct fwnode_endpoint base;
+	/*
+	 * Fields below this line will be zeroed by
+	 * v4l2_fwnode_parse_endpoint()
+	 */
+	enum v4l2_mbus_type bus_type;
+	union {
+		struct v4l2_fwnode_bus_parallel parallel;
+		struct v4l2_fwnode_bus_mipi_csi2 mipi_csi2;
+	} bus;
+	u64 *link_frequencies;
+	unsigned int nr_of_link_frequencies;
+};
+
+/**
+ * struct v4l2_fwnode_link - a link between two endpoints
+ * @local_node: pointer to device_node of this endpoint
+ * @local_port: identifier of the port this endpoint belongs to
+ * @remote_node: pointer to device_node of the remote endpoint
+ * @remote_port: identifier of the port the remote endpoint belongs to
+ */
+struct v4l2_fwnode_link {
+	struct fwnode_handle *local_node;
+	unsigned int local_port;
+	struct fwnode_handle *remote_node;
+	unsigned int remote_port;
+};
+
+int v4l2_fwnode_endpoint_parse(struct fwnode_handle *fwnode,
+			       struct v4l2_fwnode_endpoint *vep);
+struct v4l2_fwnode_endpoint *v4l2_fwnode_endpoint_alloc_parse(
+	struct fwnode_handle *fwnode);
+void v4l2_fwnode_endpoint_free(struct v4l2_fwnode_endpoint *vep);
+int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
+			   struct v4l2_fwnode_link *link);
+void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
+
+#endif /* _V4L2_FWNODE_H */