android: hal: Add Camera3 HAL

Add libcamera Android Camera HALv3 implementation.

The initial camera HAL implementation supports the LIMITED hardware
level and uses statically defined metadata and camera characteristics.

Add a build option named 'android' and adjust the build system to
selectively compile the Android camera HAL and link it against the
required Android libraries.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/android/camera3_hal.cpp

@@ -0,0 +1,111 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * camera3_hal.cpp - Android Camera HALv3 module
+ */
+
+#include <hardware/camera_common.h>
+
+#include "camera_hal_manager.h"
+#include "camera_proxy.h"
+#include "log.h"
+
+using namespace libcamera;
+
+LOG_DEFINE_CATEGORY(HAL)
+
+static CameraHalManager cameraManager;
+
+/*------------------------------------------------------------------------------
+ * Android Camera HAL callbacks
+ */
+
+static int hal_get_number_of_cameras(void)
+{
+	return cameraManager.numCameras();
+}
+
+static int hal_get_camera_info(int id, struct camera_info *info)
+{
+	return cameraManager.getCameraInfo(id, info);
+}
+
+static int hal_set_callbacks(const camera_module_callbacks_t *callbacks)
+{
+	return 0;
+}
+
+static int hal_open_legacy(const struct hw_module_t *module, const char *id,
+			   uint32_t halVersion, struct hw_device_t **device)
+{
+	return -ENOSYS;
+}
+
+static int hal_set_torch_mode(const char *camera_id, bool enabled)
+{
+	return -ENOSYS;
+}
+
+/*
+ * First entry point of the camera HAL module.
+ *
+ * Initialize the HAL but does not open any camera device yet (see hal_dev_open)
+ */
+static int hal_init()
+{
+	LOG(HAL, Info) << "Initialising Android camera HAL";
+
+	cameraManager.init();
+
+	return 0;
+}
+
+/*------------------------------------------------------------------------------
+ * Android Camera Device
+ */
+
+static int hal_dev_open(const hw_module_t *module, const char *name,
+			hw_device_t **device)
+{
+	LOG(HAL, Debug) << "Open camera " << name;
+
+	int id = atoi(name);
+	CameraProxy *proxy = cameraManager.open(id, module);
+	if (!proxy) {
+		LOG(HAL, Error)
+			<< "Failed to open camera module '" << id << "'";
+		return -ENODEV;
+	}
+
+	*device = &proxy->camera3Device()->common;
+
+	return 0;
+}
+
+static struct hw_module_methods_t hal_module_methods = {
+	.open = hal_dev_open,
+};
+
+camera_module_t HAL_MODULE_INFO_SYM = {
+	.common = {
+		.tag = HARDWARE_MODULE_TAG,
+		.module_api_version = CAMERA_MODULE_API_VERSION_2_4,
+		.hal_api_version = HARDWARE_HAL_API_VERSION,
+		.id = CAMERA_HARDWARE_MODULE_ID,
+		.name = "libcamera camera HALv3 module",
+		.author = "libcamera",
+		.methods = &hal_module_methods,
+		.dso = nullptr,
+		.reserved = {},
+	},
+
+	.get_number_of_cameras = hal_get_number_of_cameras,
+	.get_camera_info = hal_get_camera_info,
+	.set_callbacks = hal_set_callbacks,
+	.get_vendor_tag_ops = nullptr,
+	.open_legacy = hal_open_legacy,
+	.set_torch_mode = hal_set_torch_mode,
+	.init = hal_init,
+	.reserved = {},
+};