Driver core: Unified interface for firmware node properties

Add new generic routines are provided for retrieving properties from
device description objects in the platform firmware in case there are
no struct device objects for them (either those objects have not been
created yet or they do not exist at all).

The following functions are provided:

fwnode_property_present()
fwnode_property_read_u8()
fwnode_property_read_u16()
fwnode_property_read_u32()
fwnode_property_read_u64()
fwnode_property_read_string()
fwnode_property_read_u8_array()
fwnode_property_read_u16_array()
fwnode_property_read_u32_array()
fwnode_property_read_u64_array()
fwnode_property_read_string_array()

in analogy with the corresponding functions for struct device added
previously.  For all of them, the first argument is a pointer to struct
fwnode_handle (new type) that allows a device description object
(depending on what platform firmware interface is in use) to be
obtained.

Add a new macro device_for_each_child_node() for iterating over the
children of the device description object associated with a given
device and a new function device_get_child_node_count() returning the
number of a given device's child nodes.

The interface covers both ACPI and Device Trees.

Suggested-by: Grant Likely <grant.likely@linaro.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 246 insertions, 0 deletions

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 6a94ef6..c458458 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -31,6 +31,22 @@ bool device_property_present(struct device *dev, const char *propname)
 }
 EXPORT_SYMBOL_GPL(device_property_present);
 
+/**
+ * fwnode_property_present - check if a property of a firmware node is present
+ * @fwnode: Firmware node whose property to check
+ * @propname: Name of the property
+ */
+bool fwnode_property_present(struct fwnode_handle *fwnode, const char *propname)
+{
+	if (is_of_node(fwnode))
+		return of_property_read_bool(of_node(fwnode), propname);
+	else if (is_acpi_node(fwnode))
+		return !acpi_dev_prop_get(acpi_node(fwnode), propname, NULL);
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(fwnode_property_present);
+
 #define OF_DEV_PROP_READ_ARRAY(node, propname, type, val, nval) \
 	(val) ? of_property_read_##type##_array((node), (propname), (val), (nval)) \
 	      : of_property_count_elems_of_size((node), (propname), sizeof(type))
@@ -183,3 +199,233 @@ int device_property_read_string(struct device *dev, const char *propname,
 				   DEV_PROP_STRING, val, 1);
 }
 EXPORT_SYMBOL_GPL(device_property_read_string);
+
+#define FWNODE_PROP_READ_ARRAY(_fwnode_, _propname_, _type_, _proptype_, _val_, _nval_) \
+({ \
+	int _ret_; \
+	if (is_of_node(_fwnode_)) \
+		_ret_ = OF_DEV_PROP_READ_ARRAY(of_node(_fwnode_), _propname_, \
+					       _type_, _val_, _nval_); \
+	else if (is_acpi_node(_fwnode_)) \
+		_ret_ = acpi_dev_prop_read(acpi_node(_fwnode_), _propname_, \
+					   _proptype_, _val_, _nval_); \
+	else \
+		_ret_ = -ENXIO; \
+	_ret_; \
+})
+
+/**
+ * fwnode_property_read_u8_array - return a u8 array property of firmware node
+ * @fwnode: Firmware node to get the property of
+ * @propname: Name of the property
+ * @val: The values are stored here
+ * @nval: Size of the @val array
+ *
+ * Read an array of u8 properties with @propname from @fwnode and stores them to
+ * @val if found.
+ *
+ * Return: %0 if the property was found (success),
+ *	   %-EINVAL if given arguments are not valid,
+ *	   %-ENODATA if the property does not have a value,
+ *	   %-EPROTO if the property is not an array of numbers,
+ *	   %-EOVERFLOW if the size of the property is not as expected,
+ *	   %-ENXIO if no suitable firmware interface is present.
+ */
+int fwnode_property_read_u8_array(struct fwnode_handle *fwnode,
+				  const char *propname, u8 *val, size_t nval)
+{
+	return FWNODE_PROP_READ_ARRAY(fwnode, propname, u8, DEV_PROP_U8,
+				      val, nval);
+}
+EXPORT_SYMBOL_GPL(fwnode_property_read_u8_array);
+
+/**
+ * fwnode_property_read_u16_array - return a u16 array property of firmware node
+ * @fwnode: Firmware node to get the property of
+ * @propname: Name of the property
+ * @val: The values are stored here
+ * @nval: Size of the @val array
+ *
+ * Read an array of u16 properties with @propname from @fwnode and store them to
+ * @val if found.
+ *
+ * Return: %0 if the property was found (success),
+ *	   %-EINVAL if given arguments are not valid,
+ *	   %-ENODATA if the property does not have a value,
+ *	   %-EPROTO if the property is not an array of numbers,
+ *	   %-EOVERFLOW if the size of the property is not as expected,
+ *	   %-ENXIO if no suitable firmware interface is present.
+ */
+int fwnode_property_read_u16_array(struct fwnode_handle *fwnode,
+				   const char *propname, u16 *val, size_t nval)
+{
+	return FWNODE_PROP_READ_ARRAY(fwnode, propname, u16, DEV_PROP_U16,
+				      val, nval);
+}
+EXPORT_SYMBOL_GPL(fwnode_property_read_u16_array);
+
+/**
+ * fwnode_property_read_u32_array - return a u32 array property of firmware node
+ * @fwnode: Firmware node to get the property of
+ * @propname: Name of the property
+ * @val: The values are stored here
+ * @nval: Size of the @val array
+ *
+ * Read an array of u32 properties with @propname from @fwnode store them to
+ * @val if found.
+ *
+ * Return: %0 if the property was found (success),
+ *	   %-EINVAL if given arguments are not valid,
+ *	   %-ENODATA if the property does not have a value,
+ *	   %-EPROTO if the property is not an array of numbers,
+ *	   %-EOVERFLOW if the size of the property is not as expected,
+ *	   %-ENXIO if no suitable firmware interface is present.
+ */
+int fwnode_property_read_u32_array(struct fwnode_handle *fwnode,
+				   const char *propname, u32 *val, size_t nval)
+{
+	return FWNODE_PROP_READ_ARRAY(fwnode, propname, u32, DEV_PROP_U32,
+				      val, nval);
+}
+EXPORT_SYMBOL_GPL(fwnode_property_read_u32_array);
+
+/**
+ * fwnode_property_read_u64_array - return a u64 array property firmware node
+ * @fwnode: Firmware node to get the property of
+ * @propname: Name of the property
+ * @val: The values are stored here
+ * @nval: Size of the @val array
+ *
+ * Read an array of u64 properties with @propname from @fwnode and store them to
+ * @val if found.
+ *
+ * Return: %0 if the property was found (success),
+ *	   %-EINVAL if given arguments are not valid,
+ *	   %-ENODATA if the property does not have a value,
+ *	   %-EPROTO if the property is not an array of numbers,
+ *	   %-EOVERFLOW if the size of the property is not as expected,
+ *	   %-ENXIO if no suitable firmware interface is present.
+ */
+int fwnode_property_read_u64_array(struct fwnode_handle *fwnode,
+				   const char *propname, u64 *val, size_t nval)
+{
+	return FWNODE_PROP_READ_ARRAY(fwnode, propname, u64, DEV_PROP_U64,
+				      val, nval);
+}
+EXPORT_SYMBOL_GPL(fwnode_property_read_u64_array);
+
+/**
+ * fwnode_property_read_string_array - return string array property of a node
+ * @fwnode: Firmware node to get the property of
+ * @propname: Name of the property
+ * @val: The values are stored here
+ * @nval: Size of the @val array
+ *
+ * Read an string list property @propname from the given firmware node and store
+ * them to @val if found.
+ *
+ * Return: %0 if the property was found (success),
+ *	   %-EINVAL if given arguments are not valid,
+ *	   %-ENODATA if the property does not have a value,
+ *	   %-EPROTO if the property is not an array of strings,
+ *	   %-EOVERFLOW if the size of the property is not as expected,
+ *	   %-ENXIO if no suitable firmware interface is present.
+ */
+int fwnode_property_read_string_array(struct fwnode_handle *fwnode,
+				      const char *propname, const char **val,
+				      size_t nval)
+{
+	if (is_of_node(fwnode))
+		return of_property_read_string_array(of_node(fwnode), propname,
+						     val, nval);
+	else if (is_acpi_node(fwnode))
+		return acpi_dev_prop_read(acpi_node(fwnode), propname,
+					  DEV_PROP_STRING, val, nval);
+
+	return -ENXIO;
+}
+EXPORT_SYMBOL_GPL(fwnode_property_read_string_array);
+
+/**
+ * fwnode_property_read_string - return a string property of a firmware node
+ * @fwnode: Firmware node to get the property of
+ * @propname: Name of the property
+ * @val: The value is stored here
+ *
+ * Read property @propname from the given firmware node and store the value into
+ * @val if found.  The value is checked to be a string.
+ *
+ * Return: %0 if the property was found (success),
+ *	   %-EINVAL if given arguments are not valid,
+ *	   %-ENODATA if the property does not have a value,
+ *	   %-EPROTO or %-EILSEQ if the property is not a string,
+ *	   %-ENXIO if no suitable firmware interface is present.
+ */
+int fwnode_property_read_string(struct fwnode_handle *fwnode,
+				const char *propname, const char **val)
+{
+	if (is_of_node(fwnode))
+		return of_property_read_string(of_node(fwnode),propname, val);
+	else if (is_acpi_node(fwnode))
+		return acpi_dev_prop_read(acpi_node(fwnode), propname,
+					  DEV_PROP_STRING, val, 1);
+
+	return -ENXIO;
+}
+EXPORT_SYMBOL_GPL(fwnode_property_read_string);
+
+/**
+ * device_get_next_child_node - Return the next child node handle for a device
+ * @dev: Device to find the next child node for.
+ * @child: Handle to one of the device's child nodes or a null handle.
+ */
+struct fwnode_handle *device_get_next_child_node(struct device *dev,
+						 struct fwnode_handle *child)
+{
+	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
+		struct device_node *node;
+
+		node = of_get_next_available_child(dev->of_node, of_node(child));
+		if (node)
+			return &node->fwnode;
+	} else if (IS_ENABLED(CONFIG_ACPI)) {
+		struct acpi_device *node;
+
+		node = acpi_get_next_child(dev, acpi_node(child));
+		if (node)
+			return acpi_fwnode_handle(node);
+	}
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(device_get_next_child_node);
+
+/**
+ * fwnode_handle_put - Drop reference to a device node
+ * @fwnode: Pointer to the device node to drop the reference to.
+ *
+ * This has to be used when terminating device_for_each_child_node() iteration
+ * with break or return to prevent stale device node references from being left
+ * behind.
+ */
+void fwnode_handle_put(struct fwnode_handle *fwnode)
+{
+	if (is_of_node(fwnode))
+		of_node_put(of_node(fwnode));
+}
+EXPORT_SYMBOL_GPL(fwnode_handle_put);
+
+/**
+ * device_get_child_node_count - return the number of child nodes for device
+ * @dev: Device to cound the child nodes for
+ */
+unsigned int device_get_child_node_count(struct device *dev)
+{
+	struct fwnode_handle *child;
+	unsigned int count = 0;
+
+	device_for_each_child_node(dev, child)
+		count++;
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(device_get_child_node_count);