utils: ipc: Add support for enums in function parameters

There is already support for enums as struct members, but there was no
support for enums in function parameters. Add it.

This does not add support for returning enums as direct return values.

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

utils/ipc/generators/libcamera_templates/proxy_functions.tmpl

@@ -52,6 +52,9 @@
  #}
 {%- macro serialize_call(params, buf, fds) %}
 {%- for param in params %}
+{%- if param|is_enum %}
+	static_assert(sizeof({{param|name_full}}) <= 4);
+{%- endif %}
 	std::vector<uint8_t> {{param.mojom_name}}Buf;
 {%- if param|has_fd %}
 	std::vector<SharedFD> {{param.mojom_name}}Fds;
@@ -59,7 +62,11 @@
 {%- else %}
 	std::tie({{param.mojom_name}}Buf, std::ignore) =
 {%- endif %}
+{%- if param|is_enum %}
+		IPADataSerializer<uint32_t>::serialize(static_cast<uint32_t>({{param.mojom_name}})
+{%- else %}
 		IPADataSerializer<{{param|name}}>::serialize({{param.mojom_name}}
+{% endif -%}
 {{- ", &controlSerializer_" if param|needs_control_serializer -}}
 );
 {%- endfor %}
@@ -97,7 +104,12 @@
  # This code is meant to be used by macro deserialize_call.
  #}
 {%- macro deserialize_param(param, pointer, loop, buf, fds, iter, data_size) -%}
-{{"*" if pointer}}{{param.mojom_name}} = IPADataSerializer<{{param|name}}>::deserialize(
+{{"*" if pointer}}{{param.mojom_name}} =
+{%- if param|is_enum %}
+static_cast<{{param|name_full}}>(IPADataSerializer<uint32_t>::deserialize(
+{%- else %}
+IPADataSerializer<{{param|name}}>::deserialize(
+{%- endif %}
 	{{buf}}{{- ".cbegin()" if not iter}} + {{param.mojom_name}}Start,
 {%- if loop.last and not iter %}
 	{{buf}}.cend()
@@ -121,7 +133,7 @@
 {%- if param|needs_control_serializer %}
 	&controlSerializer_
 {%- endif -%}
-);
+){{")" if param|is_enum}};
 {%- endmacro -%}