[PATCH 4/6] media: v4l2-isp: Add per-block validation callback

[Jacopo Mondi <jacopo.mondi@ideasonboard.com>]

Drivers are expected to provide to the helper function
v4l2_isp_params_validate_buffer() a list of 'struct
v4l2_isp_params_block_type_info' entries, one for each supported ISP block.

The type 'struct v4l2_isp_params_block_type_info' so far only contained the
expected block size for the core framework to validate the declared block
size against the expected one.

For some blocks, drivers might want to implement more precise per-block
validations. Add a function pointer member to 'struct
v4l2_isp_params_block_type_info' to allow drivers to register a callback
and call it from the core framework during validation.

Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
 drivers/media/v4l2-core/v4l2-isp.c |  4 ++++
 include/media/v4l2-isp.h           | 11 ++++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-isp.c b/drivers/media/v4l2-core/v4l2-isp.c
index 29831f7032e9..10760659f8a3 100644
--- a/drivers/media/v4l2-core/v4l2-isp.c
+++ b/drivers/media/v4l2-core/v4l2-isp.c
@@ -114,6 +114,10 @@ int v4l2_isp_params_validate_buffer(struct device *dev, struct vb2_buffer *vb,
 			return -EINVAL;
 		}
 
+		if (type_info->block_validate &&
+		    type_info->block_validate(dev, block))
+			return -EINVAL;
+
 		block_offset += block->size;
 		buffer_size -= block->size;
 	}
diff --git a/include/media/v4l2-isp.h b/include/media/v4l2-isp.h
index d70ed6b431e7..1f35a52f978a 100644
--- a/include/media/v4l2-isp.h
+++ b/include/media/v4l2-isp.h
@@ -55,17 +55,22 @@ int v4l2_isp_params_validate_buffer_size(struct device *dev,
 /**
  * struct v4l2_isp_params_block_type_info - V4L2 ISP per-block-type info
  * @size: the block type expected size
+ * @block_validate: driver's callback to implement per-block validation
  *
  * The v4l2_isp_params_block_type_info collects information of the ISP
- * configuration block types for validation purposes. It currently only contains
- * the expected block type size.
+ * configuration block types for validation purposes. It contains the expected
+ * block type size and a function pointer where drivers can register a callback
+ * for additional per-block validation purposes. The validation function is
+ * expected to return 0 on success or a negative error number for errors.
  *
  * Drivers shall prepare a list of block type info, indexed by block type, one
  * for each supported ISP block type and correctly populate them with the
- * expected block type size.
+ * expected block type size and the optional callback.
  */
 struct v4l2_isp_params_block_type_info {
 	size_t size;
+	int (*block_validate)(struct device *dev,
+			      const struct v4l2_isp_block_header *block);
 };
 
 /**

-- 
2.53.0