media: v4l: fwnode: Add a helper function to obtain device / integer references
v4l2_fwnode_reference_parse_int_prop() will find an fwnode such that under the device's own fwnode, it will follow child fwnodes with the given property-value pair and return the resulting fwnode. Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Sakari Ailus
Mauro Carvalho Chehab
Родитель
d84285390f
Коммит
a1699a4e52
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@ -578,6 +578,293 @@ error:
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return ret;
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}
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/*
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* v4l2_fwnode_reference_get_int_prop - parse a reference with integer
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* arguments
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* @fwnode: fwnode to read @prop from
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* @notifier: notifier for @dev
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* @prop: the name of the property
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* @index: the index of the reference to get
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* @props: the array of integer property names
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* @nprops: the number of integer property names in @nprops
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*
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* First find an fwnode referred to by the reference at @index in @prop.
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*
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* Then under that fwnode, @nprops times, for each property in @props,
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* iteratively follow child nodes starting from fwnode such that they have the
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* property in @props array at the index of the child node distance from the
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* root node and the value of that property matching with the integer argument
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* of the reference, at the same index.
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*
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* The child fwnode reched at the end of the iteration is then returned to the
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* caller.
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*
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* The core reason for this is that you cannot refer to just any node in ACPI.
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* So to refer to an endpoint (easy in DT) you need to refer to a device, then
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* provide a list of (property name, property value) tuples where each tuple
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* uniquely identifies a child node. The first tuple identifies a child directly
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* underneath the device fwnode, the next tuple identifies a child node
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* underneath the fwnode identified by the previous tuple, etc. until you
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* reached the fwnode you need.
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*
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* An example with a graph, as defined in Documentation/acpi/dsd/graph.txt:
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*
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* Scope (\_SB.PCI0.I2C2)
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* {
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* Device (CAM0)
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* {
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* Name (_DSD, Package () {
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* ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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* Package () {
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* Package () {
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* "compatible",
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* Package () { "nokia,smia" }
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* },
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* },
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* ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
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* Package () {
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* Package () { "port0", "PRT0" },
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* }
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* })
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* Name (PRT0, Package() {
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* ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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* Package () {
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* Package () { "port", 0 },
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* },
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* ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
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* Package () {
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* Package () { "endpoint0", "EP00" },
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* }
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* })
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* Name (EP00, Package() {
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* ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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* Package () {
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* Package () { "endpoint", 0 },
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* Package () {
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* "remote-endpoint",
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* Package() {
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* \_SB.PCI0.ISP, 4, 0
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* }
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* },
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* }
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* })
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* }
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* }
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*
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* Scope (\_SB.PCI0)
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* {
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* Device (ISP)
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* {
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* Name (_DSD, Package () {
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* ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
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* Package () {
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* Package () { "port4", "PRT4" },
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* }
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* })
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*
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* Name (PRT4, Package() {
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* ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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* Package () {
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* Package () { "port", 4 },
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* },
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* ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
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* Package () {
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* Package () { "endpoint0", "EP40" },
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* }
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* })
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*
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* Name (EP40, Package() {
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* ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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* Package () {
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* Package () { "endpoint", 0 },
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* Package () {
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* "remote-endpoint",
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* Package () {
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* \_SB.PCI0.I2C2.CAM0,
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* 0, 0
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* }
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* },
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* }
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* })
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* }
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* }
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*
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* From the EP40 node under ISP device, you could parse the graph remote
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* endpoint using v4l2_fwnode_reference_get_int_prop with these arguments:
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*
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* @fwnode: fwnode referring to EP40 under ISP.
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* @prop: "remote-endpoint"
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* @index: 0
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* @props: "port", "endpoint"
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* @nprops: 2
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*
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* And you'd get back fwnode referring to EP00 under CAM0.
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*
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* The same works the other way around: if you use EP00 under CAM0 as the
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* fwnode, you'll get fwnode referring to EP40 under ISP.
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*
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* The same example in DT syntax would look like this:
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*
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* cam: cam0 {
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* compatible = "nokia,smia";
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*
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* port {
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* port = <0>;
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* endpoint {
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* endpoint = <0>;
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* remote-endpoint = <&isp 4 0>;
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* };
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* };
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* };
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*
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* isp: isp {
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* ports {
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* port@4 {
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* port = <4>;
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* endpoint {
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* endpoint = <0>;
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* remote-endpoint = <&cam 0 0>;
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* };
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* };
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* };
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* };
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*
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* Return: 0 on success
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* -ENOENT if no entries (or the property itself) were found
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* -EINVAL if property parsing otherwise failed
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* -ENOMEM if memory allocation failed
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*/
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static struct fwnode_handle *v4l2_fwnode_reference_get_int_prop(
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struct fwnode_handle *fwnode, const char *prop, unsigned int index,
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const char * const *props, unsigned int nprops)
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{
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struct fwnode_reference_args fwnode_args;
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unsigned int *args = fwnode_args.args;
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struct fwnode_handle *child;
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int ret;
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/*
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* Obtain remote fwnode as well as the integer arguments.
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*
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* Note that right now both -ENODATA and -ENOENT may signal
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* out-of-bounds access. Return -ENOENT in that case.
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*/
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ret = fwnode_property_get_reference_args(fwnode, prop, NULL, nprops,
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index, &fwnode_args);
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if (ret)
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return ERR_PTR(ret == -ENODATA ? -ENOENT : ret);
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/*
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* Find a node in the tree under the referred fwnode corresponding to
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* the integer arguments.
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*/
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fwnode = fwnode_args.fwnode;
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while (nprops--) {
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u32 val;
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/* Loop over all child nodes under fwnode. */
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fwnode_for_each_child_node(fwnode, child) {
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if (fwnode_property_read_u32(child, *props, &val))
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continue;
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/* Found property, see if its value matches. */
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if (val == *args)
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break;
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}
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fwnode_handle_put(fwnode);
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/* No property found; return an error here. */
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if (!child) {
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fwnode = ERR_PTR(-ENOENT);
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break;
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}
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props++;
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args++;
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fwnode = child;
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}
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return fwnode;
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}
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/*
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* v4l2_fwnode_reference_parse_int_props - parse references for async
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* sub-devices
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* @dev: struct device pointer
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* @notifier: notifier for @dev
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* @prop: the name of the property
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* @props: the array of integer property names
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* @nprops: the number of integer properties
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*
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* Use v4l2_fwnode_reference_get_int_prop to find fwnodes through reference in
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* property @prop with integer arguments with child nodes matching in properties
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* @props. Then, set up V4L2 async sub-devices for those fwnodes in the notifier
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* accordingly.
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*
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* While it is technically possible to use this function on DT, it is only
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* meaningful on ACPI. On Device tree you can refer to any node in the tree but
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* on ACPI the references are limited to devices.
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*
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* Return: 0 on success
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* -ENOENT if no entries (or the property itself) were found
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* -EINVAL if property parsing otherwisefailed
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* -ENOMEM if memory allocation failed
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*/
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static int v4l2_fwnode_reference_parse_int_props(
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struct device *dev, struct v4l2_async_notifier *notifier,
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const char *prop, const char * const *props, unsigned int nprops)
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{
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struct fwnode_handle *fwnode;
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unsigned int index;
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int ret;
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for (index = 0; !IS_ERR((fwnode = v4l2_fwnode_reference_get_int_prop(
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dev_fwnode(dev), prop, index, props,
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nprops))); index++)
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fwnode_handle_put(fwnode);
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/*
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* Note that right now both -ENODATA and -ENOENT may signal
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* out-of-bounds access. Return the error in cases other than that.
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*/
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if (PTR_ERR(fwnode) != -ENOENT && PTR_ERR(fwnode) != -ENODATA)
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return PTR_ERR(fwnode);
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ret = v4l2_async_notifier_realloc(notifier,
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notifier->num_subdevs + index);
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if (ret)
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return -ENOMEM;
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for (index = 0; !IS_ERR((fwnode = v4l2_fwnode_reference_get_int_prop(
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dev_fwnode(dev), prop, index, props,
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nprops))); index++) {
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struct v4l2_async_subdev *asd;
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if (WARN_ON(notifier->num_subdevs >= notifier->max_subdevs)) {
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ret = -EINVAL;
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goto error;
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}
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asd = kzalloc(sizeof(struct v4l2_async_subdev), GFP_KERNEL);
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if (!asd) {
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ret = -ENOMEM;
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goto error;
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}
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notifier->subdevs[notifier->num_subdevs] = asd;
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asd->match.fwnode.fwnode = fwnode;
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asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
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notifier->num_subdevs++;
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}
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return PTR_ERR(fwnode) == -ENOENT ? 0 : PTR_ERR(fwnode);
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error:
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fwnode_handle_put(fwnode);
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return ret;
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}
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Sakari Ailus <sakari.ailus@linux.intel.com>");
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MODULE_AUTHOR("Sylwester Nawrocki <s.nawrocki@samsung.com>");
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