// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Video4Linux2 generic ISP parameters and statistics support
 *
 * Copyright (C) 2025 Ideas On Board Oy
 * Author: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
 */

#include <media/v4l2-isp.h>

#include <linux/bitops.h>
#include <linux/device.h>

#include <media/videobuf2-core.h>

int v4l2_isp_params_validate_buffer_size(struct device *dev,
                                         struct vb2_buffer *vb,
                                         size_t max_size)
{
        size_t header_size = offsetof(struct v4l2_isp_params_buffer, data);
        size_t payload_size = vb2_get_plane_payload(vb, 0);

        /* Payload size can't be greater than the destination buffer size */
        if (payload_size > max_size) {
                dev_dbg(dev, "Payload size is too large: %zu\n", payload_size);
                return -EINVAL;
        }

        /* Payload size can't be smaller than the header size */
        if (payload_size < header_size) {
                dev_dbg(dev, "Payload size is too small: %zu\n", payload_size);
                return -EINVAL;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(v4l2_isp_params_validate_buffer_size);

int v4l2_isp_params_validate_buffer(struct device *dev, struct vb2_buffer *vb,
                                    const struct v4l2_isp_params_buffer *buffer,
                                    const struct v4l2_isp_params_block_type_info *type_info,
                                    size_t num_block_types)
{
        size_t header_size = offsetof(struct v4l2_isp_params_buffer, data);
        size_t payload_size = vb2_get_plane_payload(vb, 0);
        size_t block_offset = 0;
        size_t buffer_size;

        /*
         * Currently only the first version of the V4L2 ISP parameters format is
         * supported. We accept both V0 and V1 to support existing drivers
         * compatible with V4L2 ISP that use either 0 or 1 as their "first
         * version" identifiers.
         */
        if (buffer->version != V4L2_ISP_PARAMS_VERSION_V0 &&
            buffer->version != V4L2_ISP_PARAMS_VERSION_V1) {
                dev_dbg(dev,
                        "Unsupported V4L2 ISP parameters format version: %u\n",
                        buffer->version);
                return -EINVAL;
        }

        /* Validate the size reported in the header */
        buffer_size = header_size + buffer->data_size;
        if (buffer_size != payload_size) {
                dev_dbg(dev, "Data size %zu and payload size %zu are different\n",
                        buffer_size, payload_size);
                return -EINVAL;
        }

        /* Walk the list of ISP configuration blocks and validate them. */
        buffer_size = buffer->data_size;
        while (buffer_size >= sizeof(struct v4l2_isp_params_block_header)) {
                const struct v4l2_isp_params_block_type_info *info;
                const struct v4l2_isp_params_block_header *block;

                block = (const struct v4l2_isp_params_block_header *)
                        (buffer->data + block_offset);

                if (block->type >= num_block_types) {
                        dev_dbg(dev,
                                "Invalid block type %u at offset %zu\n",
                                block->type, block_offset);
                        return -EINVAL;
                }

                if (block->size > buffer_size) {
                        dev_dbg(dev, "Premature end of parameters data\n");
                        return -EINVAL;
                }

                /* It's invalid to specify both ENABLE and DISABLE. */
                if ((block->flags & (V4L2_ISP_PARAMS_FL_BLOCK_ENABLE |
                                     V4L2_ISP_PARAMS_FL_BLOCK_DISABLE)) ==
                     (V4L2_ISP_PARAMS_FL_BLOCK_ENABLE |
                     V4L2_ISP_PARAMS_FL_BLOCK_DISABLE)) {
                        dev_dbg(dev, "Invalid block flags %x at offset %zu\n",
                                block->flags, block_offset);
                        return -EINVAL;
                }

                /*
                 * Match the block reported size against the type info provided
                 * one, but allow the block to only contain the header in
                 * case it is going to be disabled.
                 */
                info = &type_info[block->type];
                if (block->size != info->size &&
                    (!(block->flags & V4L2_ISP_PARAMS_FL_BLOCK_DISABLE) ||
                    block->size != sizeof(*block))) {
                        dev_dbg(dev,
                                "Invalid block size %u (expected %zu) at offset %zu\n",
                                block->size, info->size, block_offset);
                        return -EINVAL;
                }

                block_offset += block->size;
                buffer_size -= block->size;
        }

        if (buffer_size) {
                dev_dbg(dev, "Unexpected data after the parameters buffer end\n");
                return -EINVAL;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(v4l2_isp_params_validate_buffer);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jacopo Mondi <jacopo.mondi@ideasonboard.com");
MODULE_DESCRIPTION("V4L2 generic ISP parameters and statistics helpers");