COMPMID-1047 Extract Flatten function from Im2Col for NEON

Change-Id: I80f3aaadc8cae8c9ca1a5a239e79bda302b89bd8
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/144813
Tested-by: Jenkins <bsgcomp@arm.com>
Reviewed-by: Gian Marco Iodice <gianmarco.iodice@arm.com>
diff --git a/arm_compute/runtime/NEON/functions/NEFlattenLayer.h b/arm_compute/runtime/NEON/functions/NEFlattenLayer.h
index 2c259fa..26d7c7f 100644
--- a/arm_compute/runtime/NEON/functions/NEFlattenLayer.h
+++ b/arm_compute/runtime/NEON/functions/NEFlattenLayer.h
@@ -31,11 +31,7 @@
 {
 class ITensor;
 
-/** Basic function to execute flatten. This function calls the following NEON kernel:
-*
-* -# @ref NEIm2ColKernel
-*
-*/
+/** Basic function to execute flatten layer kernel. */
 class NEFlattenLayer : public INESimpleFunction
 {
 public:
@@ -46,6 +42,17 @@
      *             w = width input tensor, h = height input tensor and d = depth input tensor. Data type supported: same as @p input
      */
     void configure(const ITensor *input, ITensor *output);
+
+    /** Static function to check if given info will lead to a valid configuration of @ref NEFlattenLayer
+     *
+     * @param[in]  input  First input tensor to flatten with at least 3 dimensions.
+     *                    The dimensions above the third will be interpreted as batches. Data types supported: U8/S8/QASYMM8/U16/S16/F16/U32/S32/F32
+     * @param[out] output Output tensor with shape [w*h*d, input_batches] where:
+     *                    w = width input tensor, h = height input tensor and d = depth input tensor. Data type supported: same as @p input
+     *
+     * @return a status
+     */
+    static Status validate(const ITensorInfo *input, const ITensorInfo *output);
 };
 } // namespace arm_compute