perf tools: Don't clone maps from parent when synthesizing forks

[linux/fpc-iii.git] / 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 <sakari.ailus@linux.intel.com>
 *
 * Copyright (C) 2012 - 2013 Samsung Electronics Co., Ltd.
 * Author: Sylwester Nawrocki <s.nawrocki@samsung.com>
 *
 * Copyright (C) 2012 Renesas Electronics Corp.
 * Author: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
 *
 * 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/mm.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-async.h>
#include <media/v4l2-fwnode.h>
#include <media/v4l2-subdev.h>

enum v4l2_fwnode_bus_type {
        V4L2_FWNODE_BUS_TYPE_GUESS = 0,
        V4L2_FWNODE_BUS_TYPE_CSI2_CPHY,
        V4L2_FWNODE_BUS_TYPE_CSI1,
        V4L2_FWNODE_BUS_TYPE_CCP2,
        NR_OF_V4L2_FWNODE_BUS_TYPE,
};

static int v4l2_fwnode_endpoint_parse_csi2_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[1 + V4L2_FWNODE_CSI2_MAX_DATA_LANES];

                bus->num_data_lanes =
                        min_t(int, V4L2_FWNODE_CSI2_MAX_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) {
                        if (rval != 1 + bus->num_data_lanes /* clock+data */) {
                                pr_warn("invalid number of 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;

        if (!fwnode_property_read_u32(fwnode, "data-enable-active", &v))
                flags |= v ? V4L2_MBUS_DATA_ENABLE_HIGH :
                        V4L2_MBUS_DATA_ENABLE_LOW;

        bus->flags = flags;

}

static void
v4l2_fwnode_endpoint_parse_csi1_bus(struct fwnode_handle *fwnode,
                                    struct v4l2_fwnode_endpoint *vep,
                                    u32 bus_type)
{
        struct v4l2_fwnode_bus_mipi_csi1 *bus = &vep->bus.mipi_csi1;
        u32 v;

        if (!fwnode_property_read_u32(fwnode, "clock-inv", &v))
                bus->clock_inv = v;

        if (!fwnode_property_read_u32(fwnode, "strobe", &v))
                bus->strobe = v;

        if (!fwnode_property_read_u32(fwnode, "data-lanes", &v))
                bus->data_lane = v;

        if (!fwnode_property_read_u32(fwnode, "clock-lanes", &v))
                bus->clock_lane = v;

        if (bus_type == V4L2_FWNODE_BUS_TYPE_CCP2)
                vep->bus_type = V4L2_MBUS_CCP2;
        else
                vep->bus_type = V4L2_MBUS_CSI1;
}

int v4l2_fwnode_endpoint_parse(struct fwnode_handle *fwnode,
                               struct v4l2_fwnode_endpoint *vep)
{
        u32 bus_type = 0;
        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));

        fwnode_property_read_u32(fwnode, "bus-type", &bus_type);

        switch (bus_type) {
        case V4L2_FWNODE_BUS_TYPE_GUESS:
                rval = v4l2_fwnode_endpoint_parse_csi2_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;
        case V4L2_FWNODE_BUS_TYPE_CCP2:
        case V4L2_FWNODE_BUS_TYPE_CSI1:
                v4l2_fwnode_endpoint_parse_csi1_bus(fwnode, vep, bus_type);

                return 0;
        default:
                pr_warn("unsupported bus type %u\n", bus_type);
                return -EINVAL;
        }
}
EXPORT_SYMBOL_GPL(v4l2_fwnode_endpoint_parse);

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);

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) {
                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);

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);

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);

static int v4l2_async_notifier_realloc(struct v4l2_async_notifier *notifier,
                                       unsigned int max_subdevs)
{
        struct v4l2_async_subdev **subdevs;

        if (max_subdevs <= notifier->max_subdevs)
                return 0;

        subdevs = kvmalloc_array(
                max_subdevs, sizeof(*notifier->subdevs),
                GFP_KERNEL | __GFP_ZERO);
        if (!subdevs)
                return -ENOMEM;

        if (notifier->subdevs) {
                memcpy(subdevs, notifier->subdevs,
                       sizeof(*subdevs) * notifier->num_subdevs);

                kvfree(notifier->subdevs);
        }

        notifier->subdevs = subdevs;
        notifier->max_subdevs = max_subdevs;

        return 0;
}

static int v4l2_async_notifier_fwnode_parse_endpoint(
        struct device *dev, struct v4l2_async_notifier *notifier,
        struct fwnode_handle *endpoint, unsigned int asd_struct_size,
        int (*parse_endpoint)(struct device *dev,
                            struct v4l2_fwnode_endpoint *vep,
                            struct v4l2_async_subdev *asd))
{
        struct v4l2_async_subdev *asd;
        struct v4l2_fwnode_endpoint *vep;
        int ret = 0;

        asd = kzalloc(asd_struct_size, GFP_KERNEL);
        if (!asd)
                return -ENOMEM;

        asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
        asd->match.fwnode =
                fwnode_graph_get_remote_port_parent(endpoint);
        if (!asd->match.fwnode) {
                dev_warn(dev, "bad remote port parent\n");
                ret = -EINVAL;
                goto out_err;
        }

        vep = v4l2_fwnode_endpoint_alloc_parse(endpoint);
        if (IS_ERR(vep)) {
                ret = PTR_ERR(vep);
                dev_warn(dev, "unable to parse V4L2 fwnode endpoint (%d)\n",
                         ret);
                goto out_err;
        }

        ret = parse_endpoint ? parse_endpoint(dev, vep, asd) : 0;
        if (ret == -ENOTCONN)
                dev_dbg(dev, "ignoring port@%u/endpoint@%u\n", vep->base.port,
                        vep->base.id);
        else if (ret < 0)
                dev_warn(dev,
                         "driver could not parse port@%u/endpoint@%u (%d)\n",
                         vep->base.port, vep->base.id, ret);
        v4l2_fwnode_endpoint_free(vep);
        if (ret < 0)
                goto out_err;

        notifier->subdevs[notifier->num_subdevs] = asd;
        notifier->num_subdevs++;

        return 0;

out_err:
        fwnode_handle_put(asd->match.fwnode);
        kfree(asd);

        return ret == -ENOTCONN ? 0 : ret;
}

static int __v4l2_async_notifier_parse_fwnode_endpoints(
        struct device *dev, struct v4l2_async_notifier *notifier,
        size_t asd_struct_size, unsigned int port, bool has_port,
        int (*parse_endpoint)(struct device *dev,
                            struct v4l2_fwnode_endpoint *vep,
                            struct v4l2_async_subdev *asd))
{
        struct fwnode_handle *fwnode;
        unsigned int max_subdevs = notifier->max_subdevs;
        int ret;

        if (WARN_ON(asd_struct_size < sizeof(struct v4l2_async_subdev)))
                return -EINVAL;

        for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
                                     dev_fwnode(dev), fwnode)); ) {
                struct fwnode_handle *dev_fwnode;
                bool is_available;

                dev_fwnode = fwnode_graph_get_port_parent(fwnode);
                is_available = fwnode_device_is_available(dev_fwnode);
                fwnode_handle_put(dev_fwnode);
                if (!is_available)
                        continue;

                if (has_port) {
                        struct fwnode_endpoint ep;

                        ret = fwnode_graph_parse_endpoint(fwnode, &ep);
                        if (ret) {
                                fwnode_handle_put(fwnode);
                                return ret;
                        }

                        if (ep.port != port)
                                continue;
                }
                max_subdevs++;
        }

        /* No subdevs to add? Return here. */
        if (max_subdevs == notifier->max_subdevs)
                return 0;

        ret = v4l2_async_notifier_realloc(notifier, max_subdevs);
        if (ret)
                return ret;

        for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
                                     dev_fwnode(dev), fwnode)); ) {
                struct fwnode_handle *dev_fwnode;
                bool is_available;

                dev_fwnode = fwnode_graph_get_port_parent(fwnode);
                is_available = fwnode_device_is_available(dev_fwnode);
                fwnode_handle_put(dev_fwnode);
                if (!is_available)
                        continue;

                if (has_port) {
                        struct fwnode_endpoint ep;

                        ret = fwnode_graph_parse_endpoint(fwnode, &ep);
                        if (ret)
                                break;

                        if (ep.port != port)
                                continue;
                }

                if (WARN_ON(notifier->num_subdevs >= notifier->max_subdevs)) {
                        ret = -EINVAL;
                        break;
                }

                ret = v4l2_async_notifier_fwnode_parse_endpoint(
                        dev, notifier, fwnode, asd_struct_size, parse_endpoint);
                if (ret < 0)
                        break;
        }

        fwnode_handle_put(fwnode);

        return ret;
}

int v4l2_async_notifier_parse_fwnode_endpoints(
        struct device *dev, struct v4l2_async_notifier *notifier,
        size_t asd_struct_size,
        int (*parse_endpoint)(struct device *dev,
                            struct v4l2_fwnode_endpoint *vep,
                            struct v4l2_async_subdev *asd))
{
        return __v4l2_async_notifier_parse_fwnode_endpoints(
                dev, notifier, asd_struct_size, 0, false, parse_endpoint);
}
EXPORT_SYMBOL_GPL(v4l2_async_notifier_parse_fwnode_endpoints);

int v4l2_async_notifier_parse_fwnode_endpoints_by_port(
        struct device *dev, struct v4l2_async_notifier *notifier,
        size_t asd_struct_size, unsigned int port,
        int (*parse_endpoint)(struct device *dev,
                            struct v4l2_fwnode_endpoint *vep,
                            struct v4l2_async_subdev *asd))
{
        return __v4l2_async_notifier_parse_fwnode_endpoints(
                dev, notifier, asd_struct_size, port, true, parse_endpoint);
}
EXPORT_SYMBOL_GPL(v4l2_async_notifier_parse_fwnode_endpoints_by_port);

/*
 * v4l2_fwnode_reference_parse - parse references for async sub-devices
 * @dev: the device node the properties of which are parsed for references
 * @notifier: the async notifier where the async subdevs will be added
 * @prop: the name of the property
 *
 * Return: 0 on success
 *         -ENOENT if no entries were found
 *         -ENOMEM if memory allocation failed
 *         -EINVAL if property parsing failed
 */
static int v4l2_fwnode_reference_parse(
        struct device *dev, struct v4l2_async_notifier *notifier,
        const char *prop)
{
        struct fwnode_reference_args args;
        unsigned int index;
        int ret;

        for (index = 0;
             !(ret = fwnode_property_get_reference_args(
                       dev_fwnode(dev), prop, NULL, 0, index, &args));
             index++)
                fwnode_handle_put(args.fwnode);

        if (!index)
                return -ENOENT;

        /*
         * Note that right now both -ENODATA and -ENOENT may signal
         * out-of-bounds access. Return the error in cases other than that.
         */
        if (ret != -ENOENT && ret != -ENODATA)
                return ret;

        ret = v4l2_async_notifier_realloc(notifier,
                                          notifier->num_subdevs + index);
        if (ret)
                return ret;

        for (index = 0; !fwnode_property_get_reference_args(
                     dev_fwnode(dev), prop, NULL, 0, index, &args);
             index++) {
                struct v4l2_async_subdev *asd;

                if (WARN_ON(notifier->num_subdevs >= notifier->max_subdevs)) {
                        ret = -EINVAL;
                        goto error;
                }

                asd = kzalloc(sizeof(*asd), GFP_KERNEL);
                if (!asd) {
                        ret = -ENOMEM;
                        goto error;
                }

                notifier->subdevs[notifier->num_subdevs] = asd;
                asd->match.fwnode = args.fwnode;
                asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
                notifier->num_subdevs++;
        }

        return 0;

error:
        fwnode_handle_put(args.fwnode);
        return ret;
}

/*
 * v4l2_fwnode_reference_get_int_prop - parse a reference with integer
 *                                      arguments
 * @fwnode: fwnode to read @prop from
 * @notifier: notifier for @dev
 * @prop: the name of the property
 * @index: the index of the reference to get
 * @props: the array of integer property names
 * @nprops: the number of integer property names in @nprops
 *
 * First find an fwnode referred to by the reference at @index in @prop.
 *
 * Then under that fwnode, @nprops times, for each property in @props,
 * iteratively follow child nodes starting from fwnode such that they have the
 * property in @props array at the index of the child node distance from the
 * root node and the value of that property matching with the integer argument
 * of the reference, at the same index.
 *
 * The child fwnode reched at the end of the iteration is then returned to the
 * caller.
 *
 * The core reason for this is that you cannot refer to just any node in ACPI.
 * So to refer to an endpoint (easy in DT) you need to refer to a device, then
 * provide a list of (property name, property value) tuples where each tuple
 * uniquely identifies a child node. The first tuple identifies a child directly
 * underneath the device fwnode, the next tuple identifies a child node
 * underneath the fwnode identified by the previous tuple, etc. until you
 * reached the fwnode you need.
 *
 * An example with a graph, as defined in Documentation/acpi/dsd/graph.txt:
 *
 *      Scope (\_SB.PCI0.I2C2)
 *      {
 *              Device (CAM0)
 *              {
 *                      Name (_DSD, Package () {
 *                              ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
 *                              Package () {
 *                                      Package () {
 *                                              "compatible",
 *                                              Package () { "nokia,smia" }
 *                                      },
 *                              },
 *                              ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
 *                              Package () {
 *                                      Package () { "port0", "PRT0" },
 *                              }
 *                      })
 *                      Name (PRT0, Package() {
 *                              ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
 *                              Package () {
 *                                      Package () { "port", 0 },
 *                              },
 *                              ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
 *                              Package () {
 *                                      Package () { "endpoint0", "EP00" },
 *                              }
 *                      })
 *                      Name (EP00, Package() {
 *                              ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
 *                              Package () {
 *                                      Package () { "endpoint", 0 },
 *                                      Package () {
 *                                              "remote-endpoint",
 *                                              Package() {
 *                                                      \_SB.PCI0.ISP, 4, 0
 *                                              }
 *                                      },
 *                              }
 *                      })
 *              }
 *      }
 *
 *      Scope (\_SB.PCI0)
 *      {
 *              Device (ISP)
 *              {
 *                      Name (_DSD, Package () {
 *                              ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
 *                              Package () {
 *                                      Package () { "port4", "PRT4" },
 *                              }
 *                      })
 *
 *                      Name (PRT4, Package() {
 *                              ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
 *                              Package () {
 *                                      Package () { "port", 4 },
 *                              },
 *                              ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
 *                              Package () {
 *                                      Package () { "endpoint0", "EP40" },
 *                              }
 *                      })
 *
 *                      Name (EP40, Package() {
 *                              ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
 *                              Package () {
 *                                      Package () { "endpoint", 0 },
 *                                      Package () {
 *                                              "remote-endpoint",
 *                                              Package () {
 *                                                      \_SB.PCI0.I2C2.CAM0,
 *                                                      0, 0
 *                                              }
 *                                      },
 *                              }
 *                      })
 *              }
 *      }
 *
 * From the EP40 node under ISP device, you could parse the graph remote
 * endpoint using v4l2_fwnode_reference_get_int_prop with these arguments:
 *
 *  @fwnode: fwnode referring to EP40 under ISP.
 *  @prop: "remote-endpoint"
 *  @index: 0
 *  @props: "port", "endpoint"
 *  @nprops: 2
 *
 * And you'd get back fwnode referring to EP00 under CAM0.
 *
 * The same works the other way around: if you use EP00 under CAM0 as the
 * fwnode, you'll get fwnode referring to EP40 under ISP.
 *
 * The same example in DT syntax would look like this:
 *
 * cam: cam0 {
 *      compatible = "nokia,smia";
 *
 *      port {
 *              port = <0>;
 *              endpoint {
 *                      endpoint = <0>;
 *                      remote-endpoint = <&isp 4 0>;
 *              };
 *      };
 * };
 *
 * isp: isp {
 *      ports {
 *              port@4 {
 *                      port = <4>;
 *                      endpoint {
 *                              endpoint = <0>;
 *                              remote-endpoint = <&cam 0 0>;
 *                      };
 *              };
 *      };
 * };
 *
 * Return: 0 on success
 *         -ENOENT if no entries (or the property itself) were found
 *         -EINVAL if property parsing otherwise failed
 *         -ENOMEM if memory allocation failed
 */
static struct fwnode_handle *v4l2_fwnode_reference_get_int_prop(
        struct fwnode_handle *fwnode, const char *prop, unsigned int index,
        const char * const *props, unsigned int nprops)
{
        struct fwnode_reference_args fwnode_args;
        u64 *args = fwnode_args.args;
        struct fwnode_handle *child;
        int ret;

        /*
         * Obtain remote fwnode as well as the integer arguments.
         *
         * Note that right now both -ENODATA and -ENOENT may signal
         * out-of-bounds access. Return -ENOENT in that case.
         */
        ret = fwnode_property_get_reference_args(fwnode, prop, NULL, nprops,
                                                 index, &fwnode_args);
        if (ret)
                return ERR_PTR(ret == -ENODATA ? -ENOENT : ret);

        /*
         * Find a node in the tree under the referred fwnode corresponding to
         * the integer arguments.
         */
        fwnode = fwnode_args.fwnode;
        while (nprops--) {
                u32 val;

                /* Loop over all child nodes under fwnode. */
                fwnode_for_each_child_node(fwnode, child) {
                        if (fwnode_property_read_u32(child, *props, &val))
                                continue;

                        /* Found property, see if its value matches. */
                        if (val == *args)
                                break;
                }

                fwnode_handle_put(fwnode);

                /* No property found; return an error here. */
                if (!child) {
                        fwnode = ERR_PTR(-ENOENT);
                        break;
                }

                props++;
                args++;
                fwnode = child;
        }

        return fwnode;
}

/*
 * v4l2_fwnode_reference_parse_int_props - parse references for async
 *                                         sub-devices
 * @dev: struct device pointer
 * @notifier: notifier for @dev
 * @prop: the name of the property
 * @props: the array of integer property names
 * @nprops: the number of integer properties
 *
 * Use v4l2_fwnode_reference_get_int_prop to find fwnodes through reference in
 * property @prop with integer arguments with child nodes matching in properties
 * @props. Then, set up V4L2 async sub-devices for those fwnodes in the notifier
 * accordingly.
 *
 * While it is technically possible to use this function on DT, it is only
 * meaningful on ACPI. On Device tree you can refer to any node in the tree but
 * on ACPI the references are limited to devices.
 *
 * Return: 0 on success
 *         -ENOENT if no entries (or the property itself) were found
 *         -EINVAL if property parsing otherwisefailed
 *         -ENOMEM if memory allocation failed
 */
static int v4l2_fwnode_reference_parse_int_props(
        struct device *dev, struct v4l2_async_notifier *notifier,
        const char *prop, const char * const *props, unsigned int nprops)
{
        struct fwnode_handle *fwnode;
        unsigned int index;
        int ret;

        index = 0;
        do {
                fwnode = v4l2_fwnode_reference_get_int_prop(dev_fwnode(dev),
                                                            prop, index,
                                                            props, nprops);
                if (IS_ERR(fwnode)) {
                        /*
                         * Note that right now both -ENODATA and -ENOENT may
                         * signal out-of-bounds access. Return the error in
                         * cases other than that.
                         */
                        if (PTR_ERR(fwnode) != -ENOENT &&
                            PTR_ERR(fwnode) != -ENODATA)
                                return PTR_ERR(fwnode);
                        break;
                }
                fwnode_handle_put(fwnode);
                index++;
        } while (1);

        ret = v4l2_async_notifier_realloc(notifier,
                                          notifier->num_subdevs + index);
        if (ret)
                return -ENOMEM;

        for (index = 0; !IS_ERR((fwnode = v4l2_fwnode_reference_get_int_prop(
                                         dev_fwnode(dev), prop, index, props,
                                         nprops))); index++) {
                struct v4l2_async_subdev *asd;

                if (WARN_ON(notifier->num_subdevs >= notifier->max_subdevs)) {
                        ret = -EINVAL;
                        goto error;
                }

                asd = kzalloc(sizeof(struct v4l2_async_subdev), GFP_KERNEL);
                if (!asd) {
                        ret = -ENOMEM;
                        goto error;
                }

                notifier->subdevs[notifier->num_subdevs] = asd;
                asd->match.fwnode = fwnode;
                asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
                notifier->num_subdevs++;
        }

        return PTR_ERR(fwnode) == -ENOENT ? 0 : PTR_ERR(fwnode);

error:
        fwnode_handle_put(fwnode);
        return ret;
}

int v4l2_async_notifier_parse_fwnode_sensor_common(
        struct device *dev, struct v4l2_async_notifier *notifier)
{
        static const char * const led_props[] = { "led" };
        static const struct {
                const char *name;
                const char * const *props;
                unsigned int nprops;
        } props[] = {
                { "flash-leds", led_props, ARRAY_SIZE(led_props) },
                { "lens-focus", NULL, 0 },
        };
        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(props); i++) {
                int ret;

                if (props[i].props && is_acpi_node(dev_fwnode(dev)))
                        ret = v4l2_fwnode_reference_parse_int_props(
                                dev, notifier, props[i].name,
                                props[i].props, props[i].nprops);
                else
                        ret = v4l2_fwnode_reference_parse(
                                dev, notifier, props[i].name);
                if (ret && ret != -ENOENT) {
                        dev_warn(dev, "parsing property \"%s\" failed (%d)\n",
                                 props[i].name, ret);
                        return ret;
                }
        }

        return 0;
}
EXPORT_SYMBOL_GPL(v4l2_async_notifier_parse_fwnode_sensor_common);

int v4l2_async_register_subdev_sensor_common(struct v4l2_subdev *sd)
{
        struct v4l2_async_notifier *notifier;
        int ret;

        if (WARN_ON(!sd->dev))
                return -ENODEV;

        notifier = kzalloc(sizeof(*notifier), GFP_KERNEL);
        if (!notifier)
                return -ENOMEM;

        ret = v4l2_async_notifier_parse_fwnode_sensor_common(sd->dev,
                                                             notifier);
        if (ret < 0)
                goto out_cleanup;

        ret = v4l2_async_subdev_notifier_register(sd, notifier);
        if (ret < 0)
                goto out_cleanup;

        ret = v4l2_async_register_subdev(sd);
        if (ret < 0)
                goto out_unregister;

        sd->subdev_notifier = notifier;

        return 0;

out_unregister:
        v4l2_async_notifier_unregister(notifier);

out_cleanup:
        v4l2_async_notifier_cleanup(notifier);
        kfree(notifier);

        return ret;
}
EXPORT_SYMBOL_GPL(v4l2_async_register_subdev_sensor_common);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Sakari Ailus <sakari.ailus@linux.intel.com>");
MODULE_AUTHOR("Sylwester Nawrocki <s.nawrocki@samsung.com>");
MODULE_AUTHOR("Guennadi Liakhovetski <g.liakhovetski@gmx.de>");