fdt: Add fdtdec_find_aliases() to deal with alias nodes

Stephen Warren pointed out that we should use nodes whether or not they
have an alias in the /aliases section. The aliases section specifies the
order so far as it can, but is not essential. Operating without alisses
is useful when the enumerated order of nodes does not matter (admittedly
rare in U-Boot).

This is considerably more complex, and it is important to keep this
complexity out of driver code. This patch creates a function
fdtdec_find_aliases() which returns an ordered list of node offsets
for a particular compatible ID, taking account of alias nodes.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/include/fdtdec.h b/include/fdtdec.h
index d871cdd..492431c 100644
--- a/include/fdtdec.h
+++ b/include/fdtdec.h
@@ -126,3 +126,50 @@ int fdtdec_get_is_enabled(const void *blob, int node, int default_val);
  * if not.
  */
 int fdtdec_check_fdt(void);
+
+/**
+ * Find the nodes for a peripheral and return a list of them in the correct
+ * order. This is used to enumerate all the peripherals of a certain type.
+ *
+ * To use this, optionally set up a /aliases node with alias properties for
+ * a peripheral. For example, for usb you could have:
+ *
+ * aliases {
+ *		usb0 = "/ehci@c5008000";
+ *		usb1 = "/ehci@c5000000";
+ * };
+ *
+ * Pass "usb" as the name to this function and will return a list of two
+ * nodes offsets: /ehci@c5008000 and ehci@c5000000.
+ *
+ * All nodes returned will match the compatible ID, as it is assumed that
+ * all peripherals use the same driver.
+ *
+ * If no alias node is found, then the node list will be returned in the
+ * order found in the fdt. If the aliases mention a node which doesn't
+ * exist, then this will be ignored. If nodes are found with no aliases,
+ * they will be added in any order.
+ *
+ * If there is a gap in the aliases, then this function return a 0 node at
+ * that position. The return value will also count these gaps.
+ *
+ * This function checks node properties and will not return nodes which are
+ * marked disabled (status = "disabled").
+ *
+ * @param blob		FDT blob to use
+ * @param name		Root name of alias to search for
+ * @param id		Compatible ID to look for
+ * @param node_list	Place to put list of found nodes
+ * @param maxcount	Maximum number of nodes to find
+ * @return number of nodes found on success, FTD_ERR_... on error
+ */
+int fdtdec_find_aliases_for_id(const void *blob, const char *name,
+			enum fdt_compat_id id, int *node_list, int maxcount);
+
+/*
+ * Get the name for a compatible ID
+ *
+ * @param id		Compatible ID to look for
+ * @return compatible string for that id
+ */
+const char *fdtdec_get_compatible(enum fdt_compat_id id);