[libcamera-devel] [PATCH 3/3] libcamera: Introduce internal controls

[Jacopo Mondi]

Introduce the enumeration of internal controls in
internal_control_ids.yaml.

The list of controls currently defines 4 draft controls which mirror the
definition of the V4L2 control they map to.

Plumb in the build system the command to generate the definition of
internal controls by re-using the same mechanism used for public
controls to make it easy to extend it to also handle internal properties
in future.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 include/libcamera/internal/meson.build  | 18 +++++++++
 src/libcamera/internal_control_ids.yaml | 54 +++++++++++++++++++++++++
 src/libcamera/meson.build               | 16 ++++++++
 3 files changed, 88 insertions(+)
 create mode 100644 src/libcamera/internal_control_ids.yaml

diff --git a/include/libcamera/internal/meson.build b/include/libcamera/internal/meson.build
index 7a780d48ee57..569940b0d2e8 100644
--- a/include/libcamera/internal/meson.build
+++ b/include/libcamera/internal/meson.build
@@ -44,3 +44,21 @@ libcamera_internal_headers = files([
     'v4l2_videodevice.h',
     'yaml_parser.h',
 ])
+
+# Generate the list of internal controls identifiers
+internal_control_source_files = ['control_ids']
+
+internal_control_headers = []
+
+foreach header : internal_control_source_files
+    input_files = files('../../../src/libcamera/internal_' + header +'.yaml',\
+                        '../' + header + '.h.in')
+    internal_control_headers += custom_target('internal_' + header + '_h',
+                                              input : input_files,
+                                              output : header + '.h',
+                                              command : [gen_controls, '--internal=True',\
+                                                                       '-o', '@OUTPUT@',\
+                                                                       '@INPUT@'],
+                                              install : false)
+endforeach
+libcamera_internal_headers += internal_control_headers
diff --git a/src/libcamera/internal_control_ids.yaml b/src/libcamera/internal_control_ids.yaml
new file mode 100644
index 000000000000..e69e0d30657c
--- /dev/null
+++ b/src/libcamera/internal_control_ids.yaml
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+#
+# Copyright (C) 2022, Google Inc.
+#
+%YAML 1.2
+---
+# Enumeration of internal libcamera controls
+# Not exposed to application, for library use only
+
+controls:
+
+  # ----------------------------------------------------------------------------
+  # Draft controls section
+
+  - VBlank:
+      type: int32_t
+      draft: true
+      description: |
+        Vertical blanking. The idle period after every frame during which no
+        image data is produced. The unit of vertical blanking is a line. Every
+        line has length of the image width plus horizontal blanking at the pixel
+        rate defined by V4L2_CID_PIXEL_RATE control in the same sub-device.
+
+        Currently identical to V4L2_CID_VBLANK.
+
+  - HBlank:
+      type: int32_t
+      draft: true
+      description: |
+        Horizontal blanking. The idle period after every line of image data
+        during which no image data is produced. The unit of horizontal blanking
+        is pixels.
+
+        Currently identical to V4L2_CID_HBLANK.
+
+  - SensorAnalogueGain:
+      type: int32_t
+      draft: true
+      description: |
+        Analogue gain is gain affecting all colour components in the pixel
+        matrix. The gain operation is performed in the analogue domain before
+        A/D conversion
+
+        Currently identical to V4L2_CID_ANALOGUE_GAIN.
+
+  - SensorExposure:
+      type: int32_t
+      draft: true
+      description: |
+        Exposure time, expressed in frame lines.
+
+        Currently identical to V4L2_CID_EXPOSURE.
+
+...
diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
index b57bee7ef6ca..4564d3dbb835 100644
--- a/src/libcamera/meson.build
+++ b/src/libcamera/meson.build
@@ -99,6 +99,7 @@ if not libyaml.found()
     libyaml = libyaml_wrap.dependency('yaml')
 endif
 
+# Generate control_ids.cpp and property_ids.cpp
 control_sources = []
 
 foreach source : control_source_files
@@ -111,6 +112,21 @@ endforeach
 
 libcamera_sources += control_sources
 
+# Generate internal_control_ids.cpp
+internal_control_source_files = ['control_ids']
+internal_control_sources = []
+
+foreach source : internal_control_source_files
+    input_files = files('internal_' + source +'.yaml', source + '.cpp.in')
+    internal_control_sources += custom_target('internal_' + source + '_cpp',
+                                              input : input_files,
+                                              output : 'internal_' + source + '.cpp',
+                                              command : [gen_controls, '--internal=True',\
+                                                                       '-o', '@OUTPUT@',\
+                                                                       '@INPUT@'])
+endforeach
+libcamera_sources += internal_control_sources
+
 gen_version = meson.project_source_root() / 'utils' / 'gen-version.sh'
 
 # Use vcs_tag() and not configure_file() or run_command(), to ensure that the
-- 
2.36.1