device property: Introduce fwnode_property_get_reference_args

The new fwnode_property_get_reference_args() interface amends the fwnode
property API with the functionality of both of_parse_phandle_with_args()
and __acpi_node_get_property_reference().

The semantics is slightly different: the cells property is ignored on ACPI
as the number of arguments can be explicitly obtained from the firmware
interface.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

5 files changed, 109 insertions, 0 deletions

diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index f8d60051efb8..681a84312dee 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -1195,6 +1195,32 @@ acpi_fwnode_get_named_child_node(const struct fwnode_handle *fwnode,
         return NULL;
 }
 
+static int
+acpi_fwnode_get_reference_args(const struct fwnode_handle *fwnode,
+                               const char *prop, const char *nargs_prop,
+                               unsigned int args_count, unsigned int index,
+                               struct fwnode_reference_args *args)
+{
+        struct acpi_reference_args acpi_args;
+        unsigned int i;
+        int ret;
+
+        ret = __acpi_node_get_property_reference(fwnode, prop, index,
+                                                 args_count, &acpi_args);
+        if (ret < 0)
+                return ret;
+        if (!args)
+                return 0;
+
+        args->nargs = acpi_args.nargs;
+        args->fwnode = acpi_fwnode_handle(acpi_args.adev);
+
+        for (i = 0; i < NR_FWNODE_REFERENCE_ARGS; i++)
+                args->args[i] = i < acpi_args.nargs ? acpi_args.args[i] : 0;
+
+        return 0;
+}
+
 static struct fwnode_handle *
 acpi_fwnode_graph_get_next_endpoint(const struct fwnode_handle *fwnode,
                                     struct fwnode_handle *prev)
@@ -1248,6 +1274,7 @@ static int acpi_fwnode_graph_parse_endpoint(const struct fwnode_handle *fwnode,
                 .get_parent = acpi_node_get_parent,                     \
                 .get_next_child_node = acpi_get_next_subnode,           \
                 .get_named_child_node = acpi_fwnode_get_named_child_node, \
+                .get_reference_args = acpi_fwnode_get_reference_args,   \
                 .graph_get_next_endpoint =                              \
                         acpi_fwnode_graph_get_next_endpoint,            \
                 .graph_get_remote_endpoint =                            \
diff --git a/drivers/base/property.c b/drivers/base/property.c
index 673e2353a2fb..d0b65bbe7e15 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -665,6 +665,34 @@ out:
 }
 EXPORT_SYMBOL_GPL(fwnode_property_match_string);
 
+/**
+ * fwnode_property_get_reference_args() - Find a reference with arguments
+ * @fwnode:     Firmware node where to look for the reference
+ * @prop:       The name of the property
+ * @nargs_prop: The name of the property telling the number of
+ *              arguments in the referred node. NULL if @nargs is known,
+ *              otherwise @nargs is ignored. Only relevant on OF.
+ * @nargs:      Number of arguments. Ignored if @nargs_prop is non-NULL.
+ * @index:      Index of the reference, from zero onwards.
+ * @args:       Result structure with reference and integer arguments.
+ *
+ * Obtain a reference based on a named property in an fwnode, with
+ * integer arguments.
+ *
+ * Caller is responsible to call fwnode_handle_put() on the returned
+ * args->fwnode pointer.
+ *
+ */
+int fwnode_property_get_reference_args(const struct fwnode_handle *fwnode,
+                                       const char *prop, const char *nargs_prop,
+                                       unsigned int nargs, unsigned int index,
+                                       struct fwnode_reference_args *args)
+{
+        return fwnode_call_int_op(fwnode, get_reference_args, prop, nargs_prop,
+                                  nargs, index, args);
+}
+EXPORT_SYMBOL_GPL(fwnode_property_get_reference_args);
+
 static int property_copy_string_array(struct property_entry *dst,
                                       const struct property_entry *src)
 {
diff --git a/drivers/of/property.c b/drivers/of/property.c
index ae46a6f0ea36..3868400972b8 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -891,6 +891,36 @@ of_fwnode_get_named_child_node(const struct fwnode_handle *fwnode,
         return NULL;
 }
 
+static int
+of_fwnode_get_reference_args(const struct fwnode_handle *fwnode,
+                             const char *prop, const char *nargs_prop,
+                             unsigned int nargs, unsigned int index,
+                             struct fwnode_reference_args *args)
+{
+        struct of_phandle_args of_args;
+        unsigned int i;
+        int ret;
+
+        if (nargs_prop)
+                ret = of_parse_phandle_with_args(to_of_node(fwnode), prop,
+                                                 nargs_prop, index, &of_args);
+        else
+                ret = of_parse_phandle_with_fixed_args(to_of_node(fwnode), prop,
+                                                       nargs, index, &of_args);
+        if (ret < 0)
+                return ret;
+        if (!args)
+                return 0;
+
+        args->nargs = of_args.args_count;
+        args->fwnode = of_fwnode_handle(of_args.np);
+
+        for (i = 0; i < NR_FWNODE_REFERENCE_ARGS; i++)
+                args->args[i] = i < of_args.args_count ? of_args.args[i] : 0;
+
+        return 0;
+}
+
 static struct fwnode_handle *
 of_fwnode_graph_get_next_endpoint(const struct fwnode_handle *fwnode,
                                   struct fwnode_handle *prev)
@@ -949,6 +979,7 @@ const struct fwnode_operations of_fwnode_ops = {
         .get_parent = of_fwnode_get_parent,
         .get_next_child_node = of_fwnode_get_next_child_node,
         .get_named_child_node = of_fwnode_get_named_child_node,
+        .get_reference_args = of_fwnode_get_reference_args,
         .graph_get_next_endpoint = of_fwnode_graph_get_next_endpoint,
         .graph_get_remote_endpoint = of_fwnode_graph_get_remote_endpoint,
         .graph_get_port_parent = of_fwnode_graph_get_port_parent,
diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
index 7b50ee4edcfc..0c35b6caf0f6 100644
--- a/include/linux/fwnode.h
+++ b/include/linux/fwnode.h
@@ -33,6 +33,20 @@ struct fwnode_endpoint {
         const struct fwnode_handle *local_fwnode;
 };
 
+#define NR_FWNODE_REFERENCE_ARGS        8
+
+/**
+ * struct fwnode_reference_args - Fwnode reference with additional arguments
+ * @fwnode:- A reference to the base fwnode
+ * @nargs: Number of elements in @args array
+ * @args: Integer arguments on the fwnode
+ */
+struct fwnode_reference_args {
+        struct fwnode_handle *fwnode;
+        unsigned int nargs;
+        unsigned int args[NR_FWNODE_REFERENCE_ARGS];
+};
+
 /**
  * struct fwnode_operations - Operations for fwnode interface
  * @get: Get a reference to an fwnode.
@@ -46,6 +60,7 @@ struct fwnode_endpoint {
  * @get_parent: Return the parent of an fwnode.
  * @get_next_child_node: Return the next child node in an iteration.
  * @get_named_child_node: Return a child node with a given name.
+ * @get_reference_args: Return a reference pointed to by a property, with args
  * @graph_get_next_endpoint: Return an endpoint node in an iteration.
  * @graph_get_remote_endpoint: Return the remote endpoint node of a local
  *                             endpoint node.
@@ -73,6 +88,10 @@ struct fwnode_operations {
         struct fwnode_handle *
         (*get_named_child_node)(const struct fwnode_handle *fwnode,
                                 const char *name);
+        int (*get_reference_args)(const struct fwnode_handle *fwnode,
+                                  const char *prop, const char *nargs_prop,
+                                  unsigned int nargs, unsigned int index,
+                                  struct fwnode_reference_args *args);
         struct fwnode_handle *
         (*graph_get_next_endpoint)(const struct fwnode_handle *fwnode,
                                    struct fwnode_handle *prev);
diff --git a/include/linux/property.h b/include/linux/property.h
index edff3f89e755..6bebee13c5e0 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -73,6 +73,10 @@ int fwnode_property_read_string(const struct fwnode_handle *fwnode,
                                 const char *propname, const char **val);
 int fwnode_property_match_string(const struct fwnode_handle *fwnode,
                                  const char *propname, const char *string);
+int fwnode_property_get_reference_args(const struct fwnode_handle *fwnode,
+                                       const char *prop, const char *nargs_prop,
+                                       unsigned int nargs, unsigned int index,
+                                       struct fwnode_reference_args *args);
 
 struct fwnode_handle *fwnode_get_parent(const struct fwnode_handle *fwnode);
 struct fwnode_handle *fwnode_get_next_parent(