utils: ipc: Add support for Flags

Add Flags<E> as a supported type in the IPA interface.

It is used in mojom with the [flags] attribute. Any field or parameter
type E that is prefixed with the [flags] attribute will direct the code
generator to generate the type name "Flags<E>" and appropriate
serialization/deserialization code for Flags<E> instead of for E.

It is usable and has been tested in struct members, function input and
output parameters, and Signal parameters. This does not add support for
returning Flags as direct return values.

Additionally, the [scopedEnum] attribute can be used on enum
definitions, which will instruct the code generator to convert it to an
enum class instead of a raw enum.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

include/libcamera/ipa/core.mojom

@@ -33,6 +33,15 @@ module libcamera;
  *     available for the type and there's no need to generate one
  * - hasFd - struct fields or empty structs only
  *   - Designate that this field or empty struct contains a SharedFD
+ * - scopedEnum - enum definitions
+ *   - Designate that this enum should be an enum class, as opposed to a pure
+ *     enum
+ * - flags - struct fields or function parameters that are enums
+ *   - Designate that this enum type E should be Flags<E> in the generated C++
+ *     code
+ *   - For example, if a struct field is defined as `[flags] ErrorFlag f;`
+ *     (where ErrorFlag is defined as an enum elsewhere in mojom), then the
+ *     generated code for this field will be `Flags<ErrorFlag> f`
  *
  * Rules:
  * - If the type is defined in a libcamera C++ header *and* a (de)serializer is

include/libcamera/ipa/ipa_interface.h

@@ -13,6 +13,7 @@
 #include <map>
 #include <vector>
 
+#include <libcamera/base/flags.h>
 #include <libcamera/base/signal.h>
 
 #include <libcamera/controls.h>

utils/ipc/generators/libcamera_templates/definition_functions.tmpl

@@ -9,7 +9,7 @@
  # \param enum Enum object whose definition is to be generated
  #}
 {%- macro define_enum(enum) -%}
-enum {{enum.mojom_name}} {
+enum{{" class" if enum|is_scoped}} {{enum.mojom_name}} {
 {%- for field in enum.fields %}
 	{{field.mojom_name}} = {{field.numeric_value}},
 {%- endfor %}

utils/ipc/generators/libcamera_templates/module_ipa_interface.h.tmpl

@@ -69,7 +69,7 @@ public:
 {%- for method in interface_event.methods %}
 	Signal<
 {%- for param in method.parameters -%}
-		{{"const " if not param|is_pod}}{{param|name}}{{" &" if not param|is_pod}}
+		{{"const " if not param|is_pod}}{{param|name}}{{" &" if not param|is_pod and not param|is_enum}}
 		{{- ", " if not loop.last}}
 {%- endfor -%}
 > {{method.mojom_name}};

utils/ipc/generators/libcamera_templates/module_ipa_proxy.h.tmpl

@@ -46,7 +46,7 @@ public:
 {%- for method in interface_event.methods %}
 	Signal<
 {%- for param in method.parameters -%}
-		{{"const " if not param|is_pod}}{{param|name}}{{" &" if not param|is_pod}}
+		{{"const " if not param|is_pod}}{{param|name}}{{" &" if not param|is_pod and not param|is_enum}}
 		{{- ", " if not loop.last}}
 {%- endfor -%}
 > {{method.mojom_name}};

utils/ipc/generators/libcamera_templates/proxy_functions.tmpl

@@ -62,7 +62,9 @@
 {%- else %}
 	std::tie({{param.mojom_name}}Buf, std::ignore) =
 {%- endif %}
-{%- if param|is_enum %}
+{%- if param|is_flags %}
+		IPADataSerializer<{{param|name_full}}>::serialize({{param.mojom_name}}
+{%- elif param|is_enum %}
 		IPADataSerializer<uint32_t>::serialize(static_cast<uint32_t>({{param.mojom_name}})
 {%- else %}
 		IPADataSerializer<{{param|name}}>::serialize({{param.mojom_name}}
@@ -105,7 +107,9 @@
  #}
 {%- macro deserialize_param(param, pointer, loop, buf, fds, iter, data_size) -%}
 {{"*" if pointer}}{{param.mojom_name}} =
-{%- if param|is_enum %}
+{%- if param|is_flags %}
+IPADataSerializer<{{param|name_full}}>::deserialize(
+{%- elif param|is_enum %}
 static_cast<{{param|name_full}}>(IPADataSerializer<uint32_t>::deserialize(
 {%- else %}
 IPADataSerializer<{{param|name}}>::deserialize(
@@ -133,7 +137,7 @@ IPADataSerializer<{{param|name}}>::deserialize(
 {%- if param|needs_control_serializer %}
 	&controlSerializer_
 {%- endif -%}
-){{")" if param|is_enum}};
+){{")" if param|is_enum and not param|is_flags}};
 {%- endmacro -%}
 
 

utils/ipc/generators/libcamera_templates/serializer.tmpl

@@ -34,6 +34,10 @@
 		std::tie({{field.mojom_name}}, std::ignore) =
 	{%- if field|is_pod %}
 			IPADataSerializer<{{field|name}}>::serialize(data.{{field.mojom_name}});
+	{%- elif field|is_flags %}
+			IPADataSerializer<{{field|name_full}}>::serialize(data.{{field.mojom_name}});
+	{%- elif field|is_enum_scoped %}
+			IPADataSerializer<uint{{field|bit_width}}_t>::serialize(static_cast<uint{{field|bit_width}}_t>(data.{{field.mojom_name}}));
 	{%- elif field|is_enum %}
 			IPADataSerializer<uint{{field|bit_width}}_t>::serialize(data.{{field.mojom_name}});
 	{%- endif %}
@@ -96,6 +100,8 @@
 		{{- check_data_size(field_size, 'dataSize', field.mojom_name, 'data')}}
 		{%- if field|is_pod %}
 		ret.{{field.mojom_name}} = IPADataSerializer<{{field|name}}>::deserialize(m, m + {{field_size}});
+		{%- elif field|is_flags %}
+		ret.{{field.mojom_name}} = IPADataSerializer<{{field|name_full}}>::deserialize(m, m + {{field_size}});
 		{%- else %}
 		ret.{{field.mojom_name}} = static_cast<{{field|name_full}}>(IPADataSerializer<uint{{field|bit_width}}_t>::deserialize(m, m + {{field_size}}));
 		{%- endif %}

utils/ipc/generators/mojom_libcamera_generator.py

@@ -74,6 +74,8 @@ def GetDefaultValue(element):
         return element.default
     if type(element.kind) == mojom.Kind:
         return '0'
+    if IsFlags(element):
+        return ''
     if mojom.IsEnumKind(element.kind):
         return f'static_cast<{element.kind.mojom_name}>(0)'
     if isinstance(element.kind, mojom.Struct) and \
@@ -184,7 +186,7 @@ def MethodParameters(method):
     params = []
     for param in method.parameters:
         params.append('const %s %s%s' % (GetNameForElement(param),
-                                         '&' if not IsPod(param) else '',
+                                         '' if IsPod(param) or IsEnum(param) else '&',
                                          param.mojom_name))
     for param in MethodParamOutputs(method):
         params.append(f'{GetNameForElement(param)} *{param.mojom_name}')
@@ -220,9 +222,30 @@ def IsControls(element):
 def IsEnum(element):
     return mojom.IsEnumKind(element.kind)
 
+
+# Only works the enum definition, not types
+def IsScoped(element):
+    attributes = getattr(element, 'attributes', None)
+    if not attributes:
+        return False
+    return 'scopedEnum' in attributes
+
+
+def IsEnumScoped(element):
+    if not IsEnum(element):
+        return False
+    return IsScoped(element.kind)
+
 def IsFd(element):
     return mojom.IsStructKind(element.kind) and element.kind.mojom_name == "SharedFD"
 
+
+def IsFlags(element):
+    attributes = getattr(element, 'attributes', None)
+    if not attributes:
+        return False
+    return 'flags' in attributes
+
 def IsMap(element):
     return mojom.IsMapKind(element.kind)
 
@@ -251,9 +274,11 @@ def ByteWidthFromCppType(t):
         raise Exception('invalid type')
     return str(int(_bit_widths[key]) // 8)
 
-
 # Get the type name for a given element
 def GetNameForElement(element):
+    # Flags
+    if IsFlags(element):
+        return f'Flags<{GetFullNameForElement(element.kind)}>'
     # structs
     if (mojom.IsEnumKind(element) or
         mojom.IsInterfaceKind(element) or
@@ -302,15 +327,18 @@ def GetNameForElement(element):
 def GetFullNameForElement(element):
     name = GetNameForElement(element)
     namespace_str = ''
-    if mojom.IsStructKind(element):
+    if (mojom.IsStructKind(element) or mojom.IsEnumKind(element)):
         namespace_str = element.module.mojom_namespace.replace('.', '::')
     elif (hasattr(element, 'kind') and
-             (mojom.IsStructKind(element.kind) or
+          (mojom.IsStructKind(element.kind) or mojom.IsEnumKind(element.kind))):
-              mojom.IsEnumKind(element.kind))):
         namespace_str = element.kind.module.mojom_namespace.replace('.', '::')
 
     if namespace_str == '':
         return name
+
+    if IsFlags(element):
+        return GetNameForElement(element)
+
     return f'{namespace_str}::{name}'
 
 def ValidateZeroLength(l, s, cap=True):
@@ -407,10 +435,13 @@ class Generator(generator.Generator):
             'is_array': IsArray,
             'is_controls': IsControls,
             'is_enum': IsEnum,
+            'is_enum_scoped': IsEnumScoped,
             'is_fd': IsFd,
+            'is_flags': IsFlags,
             'is_map': IsMap,
             'is_plain_struct': IsPlainStruct,
             'is_pod': IsPod,
+            'is_scoped': IsScoped,
             'is_str': IsStr,
             'method_input_has_fd': MethodInputHasFd,
             'method_output_has_fd': MethodOutputHasFd,