From 79389a83bc3888a900191e3990cda5c76f2ca1ec Mon Sep 17 00:00:00 2001 From: Mika Westerberg Date: Tue, 28 Mar 2017 10:52:20 +0300 Subject: [PATCH] ACPI / property: Add support for remote endpoints DT has had concept of remote endpoints for some time already. It makes possible to reference another firmware node through a property called remote-endpoint. This is already used by some subsystems like v4l2 for parsing hardware properties related to camera. This patch adds ACPI support for remote endpoints utilizing _DSD hierarchical data extensions. Signed-off-by: Mika Westerberg Signed-off-by: Sakari Ailus Signed-off-by: Rafael J. Wysocki --- drivers/acpi/property.c | 138 ++++++++++++++++++++++++++++++++++++++++ include/linux/acpi.h | 23 +++++++ 2 files changed, 161 insertions(+) diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c index 8730ce745b43..9eb7c13c5bb7 100644 --- a/drivers/acpi/property.c +++ b/drivers/acpi/property.c @@ -969,3 +969,141 @@ struct fwnode_handle *acpi_node_get_parent(struct fwnode_handle *fwnode) return NULL; } + +/** + * acpi_graph_get_next_endpoint - Get next endpoint ACPI firmware node + * @fwnode: Pointer to the parent firmware node + * @prev: Previous endpoint node or %NULL to get the first + * + * Looks up next endpoint ACPI firmware node below a given @fwnode. Returns + * %NULL if there is no next endpoint, ERR_PTR() in case of error. In case + * of success the next endpoint is returned. + */ +struct fwnode_handle *acpi_graph_get_next_endpoint(struct fwnode_handle *fwnode, + struct fwnode_handle *prev) +{ + struct fwnode_handle *port = NULL; + struct fwnode_handle *endpoint; + + if (!prev) { + do { + port = fwnode_get_next_child_node(fwnode, port); + /* Ports must have port property */ + if (fwnode_property_present(port, "port")) + break; + } while (port); + } else { + port = fwnode_get_parent(prev); + } + + if (!port) + return NULL; + + endpoint = fwnode_get_next_child_node(port, prev); + while (!endpoint) { + port = fwnode_get_next_child_node(fwnode, port); + if (!port) + break; + if (fwnode_property_present(port, "port")) + endpoint = fwnode_get_next_child_node(port, NULL); + } + + if (endpoint) { + /* Endpoints must have "endpoint" property */ + if (!fwnode_property_present(endpoint, "endpoint")) + return ERR_PTR(-EPROTO); + } + + return endpoint; +} + +/** + * acpi_graph_get_child_prop_value - Return a child with a given property value + * @fwnode: device fwnode + * @prop_name: The name of the property to look for + * @val: the desired property value + * + * Return the port node corresponding to a given port number. Returns + * the child node on success, NULL otherwise. + */ +static struct fwnode_handle *acpi_graph_get_child_prop_value( + struct fwnode_handle *fwnode, const char *prop_name, unsigned int val) +{ + struct fwnode_handle *child; + + fwnode_for_each_child_node(fwnode, child) { + u32 nr; + + if (!fwnode_property_read_u32(fwnode, prop_name, &nr)) + continue; + + if (val == nr) + return child; + } + + return NULL; +} + + +/** + * acpi_graph_get_remote_enpoint - Parses and returns remote end of an endpoint + * @fwnode: Endpoint firmware node pointing to a remote device + * @parent: Firmware node of remote port parent is filled here if not %NULL + * @port: Firmware node of remote port is filled here if not %NULL + * @endpoint: Firmware node of remote endpoint is filled here if not %NULL + * + * Function parses remote end of ACPI firmware remote endpoint and fills in + * fields requested by the caller. Returns %0 in case of success and + * negative errno otherwise. + */ +int acpi_graph_get_remote_endpoint(struct fwnode_handle *fwnode, + struct fwnode_handle **parent, + struct fwnode_handle **port, + struct fwnode_handle **endpoint) +{ + unsigned int port_nr, endpoint_nr; + struct acpi_reference_args args; + int ret; + + memset(&args, 0, sizeof(args)); + ret = acpi_node_get_property_reference(fwnode, "remote-endpoint", 0, + &args); + if (ret) + return ret; + + /* + * Always require two arguments with the reference: port and + * endpoint indices. + */ + if (args.nargs != 2) + return -EPROTO; + + fwnode = acpi_fwnode_handle(args.adev); + port_nr = args.args[0]; + endpoint_nr = args.args[1]; + + if (parent) + *parent = fwnode; + + if (!port && !endpoint) + return 0; + + fwnode = acpi_graph_get_child_prop_value(fwnode, "port", port_nr); + if (!fwnode) + return -EPROTO; + + if (port) + *port = fwnode; + + if (!endpoint) + return 0; + + fwnode = acpi_graph_get_child_prop_value(fwnode, "endpoint", + endpoint_nr); + if (!fwnode) + return -EPROTO; + + *endpoint = fwnode; + + return 0; +} diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 4eb1f5941ede..add8a96e1977 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -1001,6 +1001,13 @@ struct fwnode_handle *acpi_get_next_subnode(struct fwnode_handle *fwnode, struct fwnode_handle *child); struct fwnode_handle *acpi_node_get_parent(struct fwnode_handle *fwnode); +struct fwnode_handle *acpi_graph_get_next_endpoint(struct fwnode_handle *fwnode, + struct fwnode_handle *prev); +int acpi_graph_get_remote_endpoint(struct fwnode_handle *fwnode, + struct fwnode_handle **remote, + struct fwnode_handle **port, + struct fwnode_handle **endpoint); + struct acpi_probe_entry; typedef bool (*acpi_probe_entry_validate_subtbl)(struct acpi_subtable_header *, struct acpi_probe_entry *); @@ -1128,6 +1135,22 @@ acpi_node_get_parent(struct fwnode_handle *fwnode) return NULL; } +static inline struct fwnode_handle * +acpi_graph_get_next_endpoint(struct fwnode_handle *fwnode, + struct fwnode_handle *prev) +{ + return ERR_PTR(-ENXIO); +} + +static inline int +acpi_graph_get_remote_endpoint(struct fwnode_handle *fwnode, + struct fwnode_handle **remote, + struct fwnode_handle **port, + struct fwnode_handle **endpoint) +{ + return -ENXIO; +} + #define ACPI_DECLARE_PROBE_ENTRY(table, name, table_id, subtable, valid, data, fn) \ static const void * __acpi_table_##name[] \ __attribute__((unused)) \