ipa: mali-c55: Add Mali-C55 ISP IPA module

Add a barebones IPA module for the Mali-C55 ISP. In this initial
implementation pretty much only buffer plumbing is implemented.

Acked-by: Nayden Kanchev  <nayden.kanchev@arm.com>
Co-developed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
Acked-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 101 insertions, 0 deletions

diff --git a/src/ipa/mali-c55/ipa_context.cpp b/src/ipa/mali-c55/ipa_context.cpp
new file mode 100644
index 00000000..99f76ecd
--- /dev/null
+++ b/src/ipa/mali-c55/ipa_context.cpp
@@ -0,0 +1,101 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Ideas On Board
+ *
+ * ipa_context.cpp - MaliC55 IPA Context
+ */
+
+#include "ipa_context.h"
+
+/**
+ * \file ipa_context.h
+ * \brief Context and state information shared between the algorithms
+ */
+
+namespace libcamera::ipa::mali_c55 {
+
+/**
+ * \struct IPASessionConfiguration
+ * \brief Session configuration for the IPA module
+ *
+ * The session configuration contains all IPA configuration parameters that
+ * remain constant during the capture session, from IPA module start to stop.
+ * It is typically set during the configure() operation of the IPA module, but
+ * may also be updated in the start() operation.
+ */
+
+/**
+ * \struct IPAActiveState
+ * \brief Active state for algorithms
+ *
+ * The active state contains all algorithm-specific data that needs to be
+ * maintained by algorithms across frames. Unlike the session configuration,
+ * the active state is mutable and constantly updated by algorithms. The active
+ * state is accessible through the IPAContext structure.
+ *
+ * The active state stores two distinct categories of information:
+ *
+ *  - The consolidated value of all algorithm controls. Requests passed to
+ *    the queueRequest() function store values for controls that the
+ *    application wants to modify for that particular frame, and the
+ *    queueRequest() function updates the active state with those values.
+ *    The active state thus contains a consolidated view of the value of all
+ *    controls handled by the algorithm.
+ *
+ *  - The value of parameters computed by the algorithm when running in auto
+ *    mode. Algorithms running in auto mode compute new parameters every
+ *    time statistics buffers are received (either synchronously, or
+ *    possibly in a background thread). The latest computed value of those
+ *    parameters is stored in the active state in the process() function.
+ *
+ * Each of the members in the active state belongs to a specific algorithm. A
+ * member may be read by any algorithm, but shall only be written by its owner.
+ */
+
+/**
+ * \struct IPAFrameContext
+ * \brief Per-frame context for algorithms
+ *
+ * The frame context stores two distinct categories of information:
+ *
+ * - The value of the controls to be applied to the frame. These values are
+ *   typically set in the queueRequest() function, from the consolidated
+ *   control values stored in the active state. The frame context thus stores
+ *   values for all controls related to the algorithm, not limited to the
+ *   controls specified in the corresponding request, but consolidated from all
+ *   requests that have been queued so far.
+ *
+ *   For controls that can be set manually or computed by an algorithm
+ *   (depending on the algorithm operation mode), such as for instance the
+ *   colour gains for the AWB algorithm, the control value will be stored in
+ *   the frame context in the queueRequest() function only when operating in
+ *   manual mode. When operating in auto mode, the values are computed by the
+ *   algorithm in process(), stored in the active state, and copied to the
+ *   frame context in prepare(), just before being stored in the ISP parameters
+ *   buffer.
+ *
+ *   The queueRequest() function can also store ancillary data in the frame
+ *   context, such as flags to indicate if (and what) control values have
+ *   changed compared to the previous request.
+ *
+ * - Status information computed by the algorithm for a frame. For instance,
+ *   the colour temperature estimated by the AWB algorithm from ISP statistics
+ *   calculated on a frame is stored in the frame context for that frame in
+ *   the process() function.
+ */
+
+/**
+ * \struct IPAContext
+ * \brief Global IPA context data shared between all algorithms
+ *
+ * \var IPAContext::configuration
+ * \brief The IPA session configuration, immutable during the session
+ *
+ * \var IPAContext::activeState
+ * \brief The IPA active state, storing the latest state for all algorithms
+ *
+ * \var IPAContext::frameContexts
+ * \brief Ring buffer of per-frame contexts
+ */
+
+} /* namespace libcamera::ipa::mali_c55 */