Add psa_key_agreement_iop_t structs and docs

Signed-off-by: Paul Elliott <paul.elliott@arm.com>

tf-psa-crypto/include/psa/crypto.h

@@ -4810,6 +4810,48 @@ psa_status_t psa_verify_hash_abort(
     psa_verify_hash_interruptible_operation_t *operation);
 
 
+/**@}*/
+
+/**@}*/
+
+/**
+ *  \defgroup interruptible_key_agreement Interruptible Key Agreement
+ * @{
+ */
+
+/**
+ *  The type of the state data structure for interruptible key agreement
+ *  operations.
+ *
+ *  Before calling any function on an interruptible key agreement object, the
+ *  application must initialize it by any of the following means:
+ * - Set the structure to all-bits-zero, for example:
+ *   \code
+ *   psa_key_agreement_iop_t operation;
+ *   memset(&operation, 0, sizeof(operation));
+ *   \endcode
+ * - Initialize the structure to logical zero values, for example:
+ *   \code
+ *   psa_key_agreement_iop_t operation = {0};
+ *   \endcode
+ * - Initialize the structure to the initializer #PSA_KEY_AGREEMENT_IOP_INIT,
+ *   for example:
+ * - \code
+ *   psa_key_agreement_iop_t operation = PSA_KEY_AGREEMENT_IOP_INIT;
+ *   \endcode
+ * - Assign the result of the function psa_key_agreement_iop_init() to the
+ *   structure, for example:
+ *   \code
+ *   psa_key_agreement_iop_t operation;
+ *   operation = psa_key_agreement_iop_init();
+ *   \endcode
+ *
+ * This is an implementation-defined \c struct. Applications should not
+ * make any assumptions about the content of this structure.
+ * Implementation details can change in future versions without notice.
+ */
+typedef struct psa_key_agreement_iop_s psa_key_agreement_iop_t;
+
 /**@}*/
 
 #ifdef __cplusplus

tf-psa-crypto/include/psa/crypto_struct.h

@@ -494,6 +494,40 @@ psa_verify_hash_interruptible_operation_init(void)
     return v;
 }
 
+/**
+ * \brief The context for PSA interruptible key agreement.
+ */
+struct psa_key_agreement_iop_s {
+#if defined(MBEDTLS_PSA_CRYPTO_CLIENT) && !defined(MBEDTLS_PSA_CRYPTO_C)
+    mbedtls_psa_client_handle_t handle;
+#else
+    /**
+     *  Unique ID indicating which driver got assigned to do the
+     * operation. Since driver contexts are driver-specific, swapping
+     * drivers halfway through the operation is not supported.
+     * ID values are auto-generated in psa_crypto_driver_wrappers.h
+     * ID value zero means the context is not valid or not assigned to
+     * any driver (i.e. none of the driver contexts are active).
+     */
+    unsigned int MBEDTLS_PRIVATE(id);
+
+#endif
+};
+
+#if defined(MBEDTLS_PSA_CRYPTO_CLIENT) && !defined(MBEDTLS_PSA_CRYPTO_C)
+#define PSA_KEY_AGREEMENT_IOP_INIT { 0 }
+#else
+#define PSA_KEY_AGREEMENT_IOP_INIT { 0 }
+#endif
+
+static inline struct psa_key_agreement_iop_s
+psa_key_agreement_iop_init(void)
+{
+    const struct psa_key_agreement_iop_s v = PSA_KEY_AGREEMENT_IOP_INIT;
+
+    return v;
+}
+
 #ifdef __cplusplus
 }
 #endif