Add MD <-> PSA translation functions to MD light

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/library/md.c b/library/md.c
index 306af72..14a88ba 100644
--- a/library/md.c
+++ b/library/md.c
@@ -52,8 +52,12 @@
 #include "mbedtls/sha256.h"
 #include "mbedtls/sha512.h"
 
-#if defined(MBEDTLS_MD_SOME_PSA)
+#if defined(MBEDTLS_PSA_CRYPTO_C)
 #include <psa/crypto.h>
+#include "md_psa.h"
+#endif
+
+#if defined(MBEDTLS_MD_SOME_PSA)
 #include "psa_crypto_core.h"
 #endif
 
@@ -678,6 +682,97 @@
     return md_info->type;
 }
 
+#if defined(MBEDTLS_PSA_CRYPTO_C)
+psa_algorithm_t mbedtls_md_psa_alg_from_type(mbedtls_md_type_t md_type)
+{
+    switch (md_type) {
+#if defined(MBEDTLS_MD_CAN_MD5)
+        case MBEDTLS_MD_MD5:
+            return PSA_ALG_MD5;
+#endif
+#if defined(MBEDTLS_MD_CAN_RIPEMD160)
+        case MBEDTLS_MD_RIPEMD160:
+            return PSA_ALG_RIPEMD160;
+#endif
+#if defined(MBEDTLS_MD_CAN_SHA1)
+        case MBEDTLS_MD_SHA1:
+            return PSA_ALG_SHA_1;
+#endif
+#if defined(MBEDTLS_MD_CAN_SHA224)
+        case MBEDTLS_MD_SHA224:
+            return PSA_ALG_SHA_224;
+#endif
+#if defined(MBEDTLS_MD_CAN_SHA256)
+        case MBEDTLS_MD_SHA256:
+            return PSA_ALG_SHA_256;
+#endif
+#if defined(MBEDTLS_MD_CAN_SHA384)
+        case MBEDTLS_MD_SHA384:
+            return PSA_ALG_SHA_384;
+#endif
+#if defined(MBEDTLS_MD_CAN_SHA512)
+        case MBEDTLS_MD_SHA512:
+            return PSA_ALG_SHA_512;
+#endif
+        default:
+            return PSA_ALG_NONE;
+    }
+}
+
+mbedtls_md_type_t mbedtls_md_type_from_psa_alg(psa_algorithm_t psa_alg)
+{
+    switch (psa_alg) {
+#if defined(MBEDTLS_MD_CAN_MD5)
+        case PSA_ALG_MD5:
+            return MBEDTLS_MD_MD5;
+#endif
+#if defined(MBEDTLS_MD_CAN_RIPEMD160)
+        case PSA_ALG_RIPEMD160:
+            return MBEDTLS_MD_RIPEMD160;
+#endif
+#if defined(MBEDTLS_MD_CAN_SHA1)
+        case PSA_ALG_SHA_1:
+            return MBEDTLS_MD_SHA1;
+#endif
+#if defined(MBEDTLS_MD_CAN_SHA224)
+        case PSA_ALG_SHA_224:
+            return MBEDTLS_MD_SHA224;
+#endif
+#if defined(MBEDTLS_MD_CAN_SHA256)
+        case PSA_ALG_SHA_256:
+            return MBEDTLS_MD_SHA256;
+#endif
+#if defined(MBEDTLS_MD_CAN_SHA384)
+        case PSA_ALG_SHA_384:
+            return MBEDTLS_MD_SHA384;
+#endif
+#if defined(MBEDTLS_MD_CAN_SHA512)
+        case PSA_ALG_SHA_512:
+            return MBEDTLS_MD_SHA512;
+#endif
+        default:
+            return MBEDTLS_MD_NONE;
+    }
+}
+
+int mbedtls_md_error_from_psa(psa_status_t status)
+{
+    switch (status) {
+        case PSA_SUCCESS:
+            return 0;
+        case PSA_ERROR_NOT_SUPPORTED:
+            return MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE;
+        case PSA_ERROR_INVALID_ARGUMENT:
+            return MBEDTLS_ERR_MD_BAD_INPUT_DATA;
+        case PSA_ERROR_INSUFFICIENT_MEMORY:
+            return MBEDTLS_ERR_MD_ALLOC_FAILED;
+        default:
+            return MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED;
+    }
+}
+#endif /* MBEDTLS_PSA_CRYPTO_C */
+
+
 /************************************************************************
  * Functions above this separator are part of MBEDTLS_MD_LIGHT,         *
  * functions below are only available when MBEDTLS_MD_C is set.         *
diff --git a/library/md_psa.h b/library/md_psa.h
new file mode 100644
index 0000000..6645c83
--- /dev/null
+++ b/library/md_psa.h
@@ -0,0 +1,60 @@
+/**
+ * Translation between MD and PSA identifiers (algorithms, errors).
+ *
+ *  Note: this internal module will go away when everything becomes based on
+ *  PSA Crypto; it is a helper for the transition period.
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+#ifndef MBEDTLS_MD_PSA_H
+#define MBEDTLS_MD_PSA_H
+
+#include "common.h"
+
+#include "mbedtls/md.h"
+#include "psa/crypto.h"
+
+/**
+ * \brief           This function returns the PSA algorithm identifier
+ *                  associated with the given digest type.
+ *
+ * \param md_type   The type of digest to search for.
+ *
+ * \return          The PSA algorithm identifier associated with \p md_type.
+ * \return          PSA_ALG_NONE if the algorithm is not supported.
+ */
+psa_algorithm_t mbedtls_md_psa_alg_from_type(mbedtls_md_type_t md_type);
+
+/**
+ * \brief           This function returns the given digest type
+ *                  associated with the PSA algorithm identifier.
+ *
+ * \param psa_alg   The PSA algorithm identifier to search for.
+ *
+ * \return          The MD type associated with \p psa_alg.
+ * \return          MBEDTLS_MD_NONE if the algorithm is not supported.
+ */
+mbedtls_md_type_t mbedtls_md_type_from_psa_alg(psa_algorithm_t psa_alg);
+
+/** Convert PSA status to MD error code.
+ *
+ * \param status    PSA status.
+ *
+ * \return          The corresponding MD error code,
+ */
+int mbedtls_md_error_from_psa(psa_status_t status);
+
+#endif /* MBEDTLS_MD_PSA_H */