From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from nblzone-211-213.nblnetworks.fi ([83.145.211.213]:51104 "EHLO hillosipuli.retiisi.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751608AbdJXUc7 (ORCPT ); Tue, 24 Oct 2017 16:32:59 -0400 From: Sakari Ailus To: linux-media@vger.kernel.org Cc: niklas.soderlund@ragnatech.se, maxime.ripard@free-electrons.com, hverkuil@xs4all.nl, laurent.pinchart@ideasonboard.com, pavel@ucw.cz, sre@kernel.org Subject: [PATCH v15.2 24/32] v4l: fwnode: Add a helper function to obtain device / integer references Date: Tue, 24 Oct 2017 23:32:54 +0300 Message-Id: <20171024203254.19993-1-sakari.ailus@linux.intel.com> In-Reply-To: References: Sender: linux-media-owner@vger.kernel.org List-ID: 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 --- drivers/media/v4l2-core/v4l2-fwnode.c | 286 ++++++++++++++++++++++++++++++++++ 1 file changed, 286 insertions(+) diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c index edd2e8d983a1..ed7e363a8a6a 100644 --- a/drivers/media/v4l2-core/v4l2-fwnode.c +++ b/drivers/media/v4l2-core/v4l2-fwnode.c @@ -578,6 +578,292 @@ 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 **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 **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 "); MODULE_AUTHOR("Sylwester Nawrocki "); -- 2.11.0