crypto: caam - add Derived Key Protocol (DKP) support

Offload split key generation in CAAM engine, using DKP.
DKP is supported starting with Era 6.

Note that the way assoclen is transmitted from the job descriptor
to the shared descriptor changes - DPOVRD register is used instead
of MATH3 (where available), since DKP protocol thrashes the MATH
registers.

The replacement of MDHA split key generation with DKP has the side
effect of the crypto engine writing the authentication key, and thus
the DMA mapping direction for the buffer holding the key has to change
from DMA_TO_DEVICE to DMA_BIDIRECTIONAL.
There are two cases:
-key is inlined in descriptor - descriptor buffer mapping changes
-key is referenced - key buffer mapping changes

Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/caam/key_gen.h

@@ -6,6 +6,36 @@
  *
  */
 
+/**
+ * split_key_len - Compute MDHA split key length for a given algorithm
+ * @hash: Hashing algorithm selection, one of OP_ALG_ALGSEL_* - MD5, SHA1,
+ *        SHA224, SHA384, SHA512.
+ *
+ * Return: MDHA split key length
+ */
+static inline u32 split_key_len(u32 hash)
+{
+	/* Sizes for MDHA pads (*not* keys): MD5, SHA1, 224, 256, 384, 512 */
+	static const u8 mdpadlen[] = { 16, 20, 32, 32, 64, 64 };
+	u32 idx;
+
+	idx = (hash & OP_ALG_ALGSEL_SUBMASK) >> OP_ALG_ALGSEL_SHIFT;
+
+	return (u32)(mdpadlen[idx] * 2);
+}
+
+/**
+ * split_key_pad_len - Compute MDHA split key pad length for a given algorithm
+ * @hash: Hashing algorithm selection, one of OP_ALG_ALGSEL_* - MD5, SHA1,
+ *        SHA224, SHA384, SHA512.
+ *
+ * Return: MDHA split key pad length
+ */
+static inline u32 split_key_pad_len(u32 hash)
+{
+	return ALIGN(split_key_len(hash), 16);
+}
+
 struct split_key_result {
 	struct completion completion;
 	int err;