tools: ynl: support kdocs for flags in code generation

Lorenzo reports that after switching from enum to flags netdev
family lost ability to render kdoc (and the enum contents got
generally garbled).

Combine the flags and enum handling in uAPI handling.
Reported-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/net/ynl/ynl-gen-c.py

@@ -565,6 +565,7 @@ class EnumEntry:
             self.doc = yaml.get('doc', '')
 
         self.yaml = yaml
+        self.enum_set = enum_set
         self.c_name = c_upper(enum_set.value_pfx + self.name)
 
         if 'value' in yaml:
@@ -572,11 +573,14 @@ class EnumEntry:
             if prev:
                 self.value_change = (self.value != prev.value + 1)
         elif prev:
+            self.value_change = False
             self.value = prev.value + 1
         else:
             self.value = value_start
             self.value_change = (self.value != 0)
 
+        self.value_change = self.value_change or self.enum_set['type'] == 'flags'
+
     def __getitem__(self, key):
         return self.yaml[key]
 
@@ -586,6 +590,17 @@ class EnumEntry:
     def has_doc(self):
         return bool(self.doc)
 
+    # raw value, i.e. the id in the enum, unlike user value which is a mask for flags
+    def raw_value(self):
+        return self.value
+
+    # user value, same as raw value for enums, for flags it's the mask
+    def user_value(self):
+        if self.enum_set['type'] == 'flags':
+            return 1 << self.value
+        else:
+            return self.value
+
 
 class EnumSet:
     def __init__(self, family, yaml):
@@ -824,7 +839,7 @@ class Family:
 
     def _dictify(self):
         for elem in self.yaml['definitions']:
-            if elem['type'] == 'enum':
+            if elem['type'] == 'enum' or elem['type'] == 'flags':
                 self.consts[elem['name']] = EnumSet(self, elem)
             else:
                 self.consts[elem['name']] = elem
@@ -1973,7 +1988,8 @@ def render_uapi(family, cw):
             defines = []
             cw.nl()
 
-        if const['type'] == 'enum':
+        # Write kdoc for enum and flags (one day maybe also structs)
+        if const['type'] == 'enum' or const['type'] == 'flags':
             enum = family.consts[const['name']]
 
             if enum.has_doc():
@@ -1989,13 +2005,11 @@ def render_uapi(family, cw):
                 cw.p(' */')
 
             uapi_enum_start(family, cw, const, 'name')
-            first = True
             name_pfx = const.get('name-prefix', f"{family.name}-{const['name']}-")
             for entry in enum.entry_list:
                 suffix = ','
-                if first and 'value-start' in const:
-                    suffix = f" = {const['value-start']}" + suffix
-                first = False
+                if entry.value_change:
+                    suffix = f" = {entry.user_value()}" + suffix
                 cw.p(entry.c_name + suffix)
 
             if const.get('render-max', False):
@@ -2005,17 +2019,6 @@ def render_uapi(family, cw):
                 cw.p(max_name + ' = (__' + max_name + ' - 1)')
             cw.block_end(line=';')
             cw.nl()
-        elif const['type'] == 'flags':
-            uapi_enum_start(family, cw, const, 'name')
-            i = const.get('value-start', 0)
-            for item in const['entries']:
-                item_name = item
-                if 'name-prefix' in const:
-                    item_name = c_upper(const['name-prefix'] + item)
-                cw.p(f'{item_name} = {1 << i},')
-                i += 1
-            cw.block_end(line=';')
-            cw.nl()
         elif const['type'] == 'const':
             defines.append([c_upper(family.get('c-define-name',
                                                f"{family.name}-{const['name']}")),