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, 58 insertions, 1 deletions

diff --git a/include/media/v4l2-isp.h b/include/media/v4l2-isp.h
index 1f35a52f978a..7a54cf98c79a 100644
--- a/include/media/v4l2-isp.h
+++ b/include/media/v4l2-isp.h
@@ -53,7 +53,7 @@ int v4l2_isp_params_validate_buffer_size(struct device *dev,
 					 size_t max_size);
 
 /**
- * struct v4l2_isp_params_block_type_info - V4L2 ISP per-block-type info
+ * struct v4l2_isp_params_block_type_info - V4L2 ISP params per-block-type info
  * @size: the block type expected size
  * @block_validate: driver's callback to implement per-block validation
  *
@@ -97,4 +97,61 @@ int v4l2_isp_params_validate_buffer(struct device *dev, struct vb2_buffer *vb,
 				    const struct v4l2_isp_params_block_type_info *type_info,
 				    size_t num_block_types);
 
+/**
+ * struct v4l2_isp_stats_block_type_info - V4L2 ISP stats per-block-type info
+ * @size: the block type expected size
+ *
+ * The v4l2_isp_stats_block_type_info collects information of the ISP
+ * statistics block types for validation purposes. It currently only contains
+ * the expected block size.
+ *
+ * Drivers shall prepare a list of statistics block type info, indexed by block
+ * type, one for each supported ISP statistics block type and correctly populate
+ * them with the expected block size.
+ */
+struct v4l2_isp_stats_block_type_info {
+	size_t size;
+};
+
+/**
+ * v4l2_isp_stats_init_buffer - Initialize a statistics buffer
+ *
+ * Initialize a buffer of statistics. Only set the 'version' field and reset
+ * 'data_size' to 0.
+ *
+ * @buf: the v4l2_isp_buffer to initialize
+ * @version: the v4l2-isp serialization format version used by the driver
+ */
+void v4l2_isp_stats_init_buffer(struct v4l2_isp_buffer *buf,
+				enum v4l2_isp_version version);
+
+/**
+ * v4l2_isp_stats_init_block - Create and initialize a new block in a statistics
+ *			       buffer
+ * @dev: the driver's device pointer
+ * @buf: the v4l2_isp_buffer where statistics are serialized
+ * @type_info: the array of per-block-type validation info
+ * @num_block_types: the number of block types in the type_info array
+ * @block_type: the type of the statistics block to initialize
+ * @max_size: the maximum size of the data[] member of @buf
+ *
+ * This function locates and initialize a new statistics block in @buf for the
+ * driver to populate its content. The function checks that enough space for the
+ * requested @block_type is available in @buf and increments the 'data_size'
+ * member of @buf. The newly created statistics block's header is initialized
+ * with the size and type information provided by the caller in @type_info.
+ *
+ * Drivers should call this function before populating a new statistics block
+ * content.
+ *
+ * Returns a pointer to the next available location in @buf, or an error pointer
+ * if the requested @block_size is not available in @buf or @block_type is not
+ * valid.
+ */
+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);
+
 #endif /* _V4L2_ISP_H_ */