media: v4l2-isp: Add helpers for stats buffer

Add two helper functions to v4l2-isp to handle statistics:

- v4l2_isp_stats_init_buffer() to initialize a statistics buffer
- v4l2_isp_stats_init_block() to initialize a statistics block in the
  next available memory location of a buffer

The v4l2_isp_stats_init_buffer() resets the data size counter of the
buffer and initializes its 'version' field.

The v4l2_isp_stats_init_block() helper accepts the type of the stats
block about to be populated, an array of per-block-type information and
the maximum size of the v4l2-isp buffer. If enough space for the new
block is available, the function increments the
v4l2_isp_buffer.data_size counter, initializes the new stats block
header and returns a pointer to the block for the driver to populate it.

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/drivers/media/v4l2-core/v4l2-isp.c b/drivers/media/v4l2-core/v4l2-isp.c
index f497471e9f18..1eb46e080afa 100644
--- a/drivers/media/v4l2-core/v4l2-isp.c
+++ b/drivers/media/v4l2-core/v4l2-isp.c
@@ -130,6 +130,58 @@ int v4l2_isp_params_validate_buffer(struct device *dev, struct vb2_buffer *vb,
 }
 EXPORT_SYMBOL_GPL(v4l2_isp_params_validate_buffer);
 
+void v4l2_isp_stats_init_buffer(struct v4l2_isp_buffer *buf,
+				enum v4l2_isp_version version)
+{
+	if (WARN_ON(!buf))
+		return;
+
+	if (WARN_ON(version > V4L2_ISP_VERSION_V1))
+		return;
+
+	buf->version = version;
+	buf->data_size = 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_isp_stats_init_buffer);
+
+struct v4l2_isp_block_header *
+v4l2_isp_stats_init_block(struct device *dev, struct v4l2_isp_buffer *buf,
+			  const struct v4l2_isp_stats_block_type_info *type_info,
+			  size_t num_block_types, unsigned int block_type,
+			  size_t max_size)
+{
+	const struct v4l2_isp_stats_block_type_info *block_info;
+	struct v4l2_isp_block_header *header;
+	size_t used;
+
+	if (WARN_ON(!dev || !buf || !type_info))
+		return ERR_PTR(-EINVAL);
+
+	if (block_type >= num_block_types) {
+		dev_err(dev, "Invalid block type %u\n", block_type);
+		return ERR_PTR(-EINVAL);
+	}
+
+	block_info = &type_info[block_type];
+	used = buf->data_size;
+
+	if (used + block_info->size > max_size) {
+		dev_err(dev, "No space for stats block type %u of size %zu\n",
+			block_type, block_info->size);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	buf->data_size += block_info->size;
+
+	header = (struct v4l2_isp_block_header *)&buf->data[used];
+	header->type = block_type;
+	header->size = block_info->size;
+	header->flags = 0;
+
+	return header;
+}
+EXPORT_SYMBOL_GPL(v4l2_isp_stats_init_block);
+
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Jacopo Mondi <jacopo.mondi@ideasonboard.com");
 MODULE_DESCRIPTION("V4L2 generic ISP parameters and statistics helpers");