dm: core: Add device-based 'read' functions to access DT

It is common to read a device-tree property from the node associated with
a device. Add convenience functions to do this so that drivers do not need
to deal with accessing the ofnode from the device.

These functions all start with 'dev_read_' to provide consistent naming
for all functions which read information from a device's device tree node.

These are inlined when using the flat DT to save code size. The live tree
implementation is added in a later commit.

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 383 insertions, 0 deletions

diff --git a/include/dm/read.h b/include/dm/read.h
new file mode 100644
index 0000000000..4ce2bc2d6e
--- /dev/null
+++ b/include/dm/read.h
@@ -0,0 +1,383 @@
+/*
+ * Function to read values from the device tree node attached to a udevice.
+ *
+ * Copyright (c) 2017 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef _DM_READ_H
+#define _DM_READ_H
+
+#include <dm/fdtaddr.h>
+#include <dm/ofnode.h>
+#include <dm/uclass.h>
+
+#if CONFIG_IS_ENABLED(OF_LIVE)
+static inline const struct device_node *dev_np(struct udevice *dev)
+{
+	return ofnode_to_np(dev->node);
+}
+#else
+static inline const struct device_node *dev_np(struct udevice *dev)
+{
+	return NULL;
+}
+#endif
+
+/**
+ * dev_ofnode() - get the DT node reference associated with a udevice
+ *
+ * @dev:	device to check
+ * @return reference of the the device's DT node
+ */
+static inline ofnode dev_ofnode(struct udevice *dev)
+{
+	return dev->node;
+}
+
+static inline bool dev_of_valid(struct udevice *dev)
+{
+	return ofnode_valid(dev_ofnode(dev));
+}
+
+#ifdef CONFIG_DM_DEV_READ_INLINE
+
+static inline int dev_read_u32_default(struct udevice *dev,
+				       const char *propname, int def)
+{
+	return ofnode_read_u32_default(dev_ofnode(dev), propname, def);
+}
+
+/**
+ * dev_read_string() - Read a string from a device's DT property
+ *
+ * @dev:	device to read DT property from
+ * @propname:	name of the property to read
+ * @return string from property value, or NULL if there is no such property
+ */
+static inline const char *dev_read_string(struct udevice *dev,
+					  const char *propname)
+{
+	return ofnode_read_string(dev_ofnode(dev), propname);
+}
+
+/**
+ * dev_read_bool() - read a boolean value from a device's DT property
+ *
+ * @dev:	device to read DT property from
+ * @propname:	name of property to read
+ * @return true if property is present (meaning true), false if not present
+ */
+static inline bool dev_read_bool(struct udevice *dev, const char *propname)
+{
+	return ofnode_read_bool(dev_ofnode(dev), propname);
+}
+
+/**
+ * dev_read_subnode() - find a named subnode of a device
+ *
+ * @dev:	device whose DT node contains the subnode
+ * @subnode_name: name of subnode to find
+ * @return reference to subnode (which can be invalid if there is no such
+ * subnode)
+ */
+static inline ofnode dev_read_subnode(struct udevice *dev,
+				      const char *subbnode_name)
+{
+	return ofnode_find_subnode(dev_ofnode(dev), subbnode_name);
+}
+
+/**
+ * dev_read_size() - read the size of a property
+ *
+ * @dev: device to check
+ * @propname: property to check
+ * @return size of property if present, or -EINVAL if not
+ */
+static inline int dev_read_size(struct udevice *dev, const char *propname)
+{
+	return ofnode_read_size(dev_ofnode(dev), propname);
+}
+
+/**
+ * dev_read_addr_index() - Get the indexed reg property of a device
+ *
+ * @dev: Device to read from
+ * @index: the 'reg' property can hold a list of <addr, size> pairs
+ *	   and @index is used to select which one is required
+ *
+ * @return address or FDT_ADDR_T_NONE if not found
+ */
+static inline fdt_addr_t dev_read_addr_index(struct udevice *dev, int index)
+{
+	return devfdt_get_addr_index(dev, index);
+}
+
+/**
+ * dev_read_addr() - Get the reg property of a device
+ *
+ * @dev: Device to read from
+ *
+ * @return address or FDT_ADDR_T_NONE if not found
+ */
+static inline fdt_addr_t dev_read_addr(struct udevice *dev)
+{
+	return devfdt_get_addr(dev);
+}
+
+/**
+ * dev_read_addr_size() - get address and size from a device property
+ *
+ * This does no address translation. It simply reads an property that contains
+ * an address and a size value, one after the other.
+ *
+ * @dev: Device to read from
+ * @propname: property to read
+ * @sizep: place to put size value (on success)
+ * @return address value, or FDT_ADDR_T_NONE on error
+ */
+static inline fdt_addr_t dev_read_addr_size(struct udevice *dev,
+					    const char *propname,
+					    fdt_size_t *sizep)
+{
+	return ofnode_get_addr_size(dev_ofnode(dev), propname, sizep);
+}
+
+/**
+ * dev_read_name() - get the name of a device's node
+ *
+ * @node: valid node to look up
+ * @return name of node
+ */
+static inline const char *dev_read_name(struct udevice *dev)
+{
+	return ofnode_get_name(dev_ofnode(dev));
+}
+
+/**
+ * dev_read_stringlist_search() - find string in a string list and return index
+ *
+ * Note that it is possible for this function to succeed on property values
+ * that are not NUL-terminated. That's because the function will stop after
+ * finding the first occurrence of @string. This can for example happen with
+ * small-valued cell properties, such as #address-cells, when searching for
+ * the empty string.
+ *
+ * @dev: device to check
+ * @propname: name of the property containing the string list
+ * @string: string to look up in the string list
+ *
+ * @return:
+ *   the index of the string in the list of strings
+ *   -ENODATA if the property is not found
+ *   -EINVAL on some other error
+ */
+static inline int dev_read_stringlist_search(struct udevice *dev,
+					     const char *propname,
+					     const char *string)
+{
+	return ofnode_stringlist_search(dev_ofnode(dev), propname, string);
+}
+
+/**
+ * dev_read_phandle_with_args() - Find a node pointed by phandle in a list
+ *
+ * This function is useful to parse lists of phandles and their arguments.
+ * Returns 0 on success and fills out_args, on error returns appropriate
+ * errno value.
+ *
+ * Caller is responsible to call of_node_put() on the returned out_args->np
+ * pointer.
+ *
+ * Example:
+ *
+ * phandle1: node1 {
+ *	#list-cells = <2>;
+ * }
+ *
+ * phandle2: node2 {
+ *	#list-cells = <1>;
+ * }
+ *
+ * node3 {
+ *	list = <&phandle1 1 2 &phandle2 3>;
+ * }
+ *
+ * To get a device_node of the `node2' node you may call this:
+ * dev_read_phandle_with_args(dev, "list", "#list-cells", 0, 1, &args);
+ *
+ * @dev:	device whose node containing a list
+ * @list_name:	property name that contains a list
+ * @cells_name:	property name that specifies phandles' arguments count
+ * @cells_count: Cell count to use if @cells_name is NULL
+ * @index:	index of a phandle to parse out
+ * @out_args:	optional pointer to output arguments structure (will be filled)
+ * @return 0 on success (with @out_args filled out if not NULL), -ENOENT if
+ *	@list_name does not exist, -EINVAL if a phandle was not found,
+ *	@cells_name could not be found, the arguments were truncated or there
+ *	were too many arguments.
+ */
+static inline int dev_read_phandle_with_args(struct udevice *dev,
+		const char *list_name, const char *cells_name, int cell_count,
+		int index, struct ofnode_phandle_args *out_args)
+{
+	return ofnode_parse_phandle_with_args(dev_ofnode(dev), list_name,
+					      cells_name, cell_count, index,
+					      out_args);
+}
+
+/**
+ * dev_read_addr_cells() - Get the number of address cells for a device's node
+ *
+ * This walks back up the tree to find the closest #address-cells property
+ * which controls the given node.
+ *
+ * @dev: devioe to check
+ * @return number of address cells this node uses
+ */
+static inline int dev_read_addr_cells(struct udevice *dev)
+{
+	return fdt_address_cells(gd->fdt_blob, dev_of_offset(dev));
+}
+
+/**
+ * dev_read_size_cells() - Get the number of size cells for a device's node
+ *
+ * This walks back up the tree to find the closest #size-cells property
+ * which controls the given node.
+ *
+ * @dev: devioe to check
+ * @return number of size cells this node uses
+ */
+static inline int dev_read_size_cells(struct udevice *dev)
+{
+	return fdt_size_cells(gd->fdt_blob, dev_of_offset(dev));
+}
+
+/**
+ * dev_read_phandle() - Get the phandle from a device
+ *
+ * @dev: device to check
+ * @return phandle (1 or greater), or 0 if no phandle or other error
+ */
+static inline int dev_read_phandle(struct udevice *dev)
+{
+	return fdt_get_phandle(gd->fdt_blob, dev_of_offset(dev));
+}
+
+/**
+ * dev_read_prop()- - read a property from a device's node
+ *
+ * @dev: device to check
+ * @propname: property to read
+ * @lenp: place to put length on success
+ * @return pointer to property, or NULL if not found
+ */
+static inline const u32 *dev_read_prop(struct udevice *dev,
+				       const char *propname, int *lenp)
+{
+	return ofnode_read_prop(dev_ofnode(dev), propname, lenp);
+}
+
+/**
+ * dev_read_alias_seq() - Get the alias sequence number of a node
+ *
+ * This works out whether a node is pointed to by an alias, and if so, the
+ * sequence number of that alias. Aliases are of the form <base><num> where
+ * <num> is the sequence number. For example spi2 would be sequence number 2.
+ *
+ * @dev: device to look up
+ * @devnump: set to the sequence number if one is found
+ * @return 0 if a sequence was found, -ve if not
+ */
+static inline int dev_read_alias_seq(struct udevice *dev, int *devnump)
+{
+	return fdtdec_get_alias_seq(gd->fdt_blob, dev->uclass->uc_drv->name,
+				    dev_of_offset(dev), devnump);
+}
+
+/**
+ * dev_read_u32_array() - Find and read an array of 32 bit integers
+ *
+ * Search for a property in a device node and read 32-bit value(s) from
+ * it.
+ *
+ * The out_values is modified only if a valid u32 value can be decoded.
+ *
+ * @dev: device to look up
+ * @propname:	name of the property to read
+ * @out_values:	pointer to return value, modified only if return value is 0
+ * @sz:		number of array elements to read
+ * @return 0 on success, -EINVAL if the property does not exist, -ENODATA if
+ * property does not have a value, and -EOVERFLOW if the property data isn't
+ * large enough.
+ */
+static inline int dev_read_u32_array(struct udevice *dev, const char *propname,
+				     u32 *out_values, size_t sz)
+{
+	return ofnode_read_u32_array(dev_ofnode(dev), propname, out_values, sz);
+}
+
+/**
+ * dev_read_first_subnode() - find the first subnode of a device's node
+ *
+ * @dev: device to look up
+ * @return reference to the first subnode (which can be invalid if the device's
+ * node has no subnodes)
+ */
+static inline ofnode dev_read_first_subnode(struct udevice *dev)
+{
+	return ofnode_first_subnode(dev_ofnode(dev));
+}
+
+/**
+ * ofnode_next_subnode() - find the next sibling of a subnode
+ *
+ * @node:	valid reference to previous node (sibling)
+ * @return reference to the next subnode (which can be invalid if the node
+ * has no more siblings)
+ */
+static inline ofnode dev_read_next_subnode(ofnode node)
+{
+	return ofnode_next_subnode(node);
+}
+
+/**
+ * dev_read_u8_array_ptr() - find an 8-bit array
+ *
+ * Look up a device's node property and return a pointer to its contents as a
+ * byte array of given length. The property must have at least enough data
+ * for the array (count bytes). It may have more, but this will be ignored.
+ * The data is not copied.
+ *
+ * @dev: device to look up
+ * @propname: name of property to find
+ * @sz: number of array elements
+ * @return pointer to byte array if found, or NULL if the property is not
+ *		found or there is not enough data
+ */
+static inline const uint8_t *dev_read_u8_array_ptr(struct udevice *dev,
+					const char *propname, size_t sz)
+{
+	return ofnode_read_u8_array_ptr(dev_ofnode(dev), propname, sz);
+}
+
+#endif /* CONFIG_DM_DEV_READ_INLINE */
+
+/**
+ * dev_for_each_subnode() - Helper function to iterate through subnodes
+ *
+ * This creates a for() loop which works through the subnodes in a device's
+ * device-tree node.
+ *
+ * @subnode: ofnode holding the current subnode
+ * @dev: device to use for interation (struct udevice *)
+ */
+#define dev_for_each_subnode(subnode, dev) \
+	for (subnode = dev_read_first_subnode(dev); \
+	     ofnode_valid(subnode); \
+	     subnode = ofnode_next_subnode(subnode))
+
+#endif