media: v4l: fwnode: Add a helper function to obtain device / integer references (a1699a4e) · Commits · e / devices / android_kernel_oneplus_sm7250

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

+287 −0

Original line number	Diff line number	Diff line
		@@ -578,6 +578,293 @@ static int v4l2_fwnode_reference_parse(
		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;
		unsigned int *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;

		for (index = 0; !IS_ERR((fwnode = v4l2_fwnode_reference_get_int_prop(
		dev_fwnode(dev), prop, index, props,
		nprops))); index++)
		fwnode_handle_put(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);

		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 = 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;
		}

		MODULE_LICENSE("GPL");
		MODULE_AUTHOR("Sakari Ailus <sakari.ailus@linux.intel.com>");
		MODULE_AUTHOR("Sylwester Nawrocki <s.nawrocki@samsung.com>");