dtoc: Set up the uclasses that are used

We only care about uclasses that are actually used. This is determined by
the drivers that use them. Check all the used drivers and build a list of
'valid' uclasses.

Also add references to the uclasses so we can generate C code that uses
them. Attach a uclass to each valid driver.

For the tests, now that we have uclasses we must create an explicit test
for the case where a node does not have one. This should only happen if
the source code does not build, or the source-code scanning fails to find
it.

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

tools/dtoc/src_scan.py

@@ -74,6 +74,7 @@ class Driver:
             found after this one
         warn_dups (bool): True if the duplicates are not distinguisble using
             the phase
+        uclass (Uclass): uclass for this driver
     """
     def __init__(self, name, fname):
         self.name = name
@@ -89,6 +90,7 @@ class Driver:
         self.headers = []
         self.dups = []
         self.warn_dups = False
+        self.uclass = None
 
     def __eq__(self, other):
         return (self.name == other.name and
@@ -123,6 +125,10 @@ class UclassDriver:
         alias_path_to_num (dict): Convert a path to an alias number
             key (str): Full path to node (e.g. '/soc/pci')
             seq (int): Alias number, e.g. 2 for "pci2"
+        devs (list): List of devices in this uclass, each a Node
+        node_refs (dict): References in the linked list of devices:
+            key (int): Sequence number (0=first, n-1=last, -1=head, n=tail)
+            value (str): Reference to the device at that position
     """
     def __init__(self, name):
         self.name = name
@@ -134,6 +140,8 @@ class UclassDriver:
         self.per_child_plat = ''
         self.alias_num_to_node = {}
         self.alias_path_to_num = {}
+        self.devs = []
+        self.node_refs = {}
 
     def __eq__(self, other):
         return (self.name == other.name and
@@ -639,6 +647,12 @@ class Scanner:
             else:
                 self.scan_driver(self._basedir + '/' + fname)
 
+        # Get the uclass for each driver
+        # TODO: Can we just get the uclass for the ones we use, e.g. in
+        # mark_used()?
+        for driver in self._drivers.values():
+            driver.uclass = self._uclass.get(driver.uclass_id)
+
     def mark_used(self, nodes):
         """Mark the drivers associated with a list of nodes as 'used'
 
@@ -682,3 +696,34 @@ class Scanner:
                 uclass.alias_path_to_num[node.path] = int(num)
                 return True
         return False
+
+    def assign_seq(self, node):
+        """Figure out the sequence number for a node
+
+        This looks in the node's uclass and assigns a sequence number if needed,
+        based on the aliases and other nodes in that uclass.
+
+        It updates the uclass alias_path_to_num and alias_num_to_node
+
+        Args:
+            node (Node): Node object to look up
+        """
+        if node.driver and node.seq == -1 and node.uclass:
+            uclass = node.uclass
+            num = uclass.alias_path_to_num.get(node.path)
+            if num is not None:
+                return num
+            else:
+                # Dynamically allocate the next available value after all
+                # existing ones
+                if uclass.alias_num_to_node:
+                    start = max(uclass.alias_num_to_node.keys())
+                else:
+                    start = -1
+                for seq in range(start + 1, 1000):
+                    if seq not in uclass.alias_num_to_node:
+                        break
+                uclass.alias_path_to_num[node.path] = seq
+                uclass.alias_num_to_node[seq] = node
+                return seq
+        return None