diff --git a/include/mbedtls/sha512.h b/include/mbedtls/sha512.h
index 020f95d..c06ceed 100644
--- a/include/mbedtls/sha512.h
+++ b/include/mbedtls/sha512.h
@@ -37,6 +37,7 @@
 
 /* MBEDTLS_ERR_SHA512_HW_ACCEL_FAILED is deprecated and should not be used. */
 #define MBEDTLS_ERR_SHA512_HW_ACCEL_FAILED                -0x0039  /**< SHA-512 hardware accelerator failed */
+#define MBEDTLS_ERR_SHA512_BAD_INPUT_DATA                 -0x0075  /**< SHA-512 input data was malformed. */
 
 #ifdef __cplusplus
 extern "C" {
@@ -70,22 +71,26 @@
 /**
  * \brief          This function initializes a SHA-512 context.
  *
- * \param ctx      The SHA-512 context to initialize.
+ * \param ctx      The SHA-512 context to initialize. This must
+ *                 not be \c NULL.
  */
 void mbedtls_sha512_init( mbedtls_sha512_context *ctx );
 
 /**
  * \brief          This function clears a SHA-512 context.
  *
- * \param ctx      The SHA-512 context to clear.
+ * \param ctx      The SHA-512 context to clear. This may be \c NULL,
+ *                 in which case this function does nothing. If it
+ *                 is not \c NULL, it must point to an initialized
+ *                 SHA-512 context.
  */
 void mbedtls_sha512_free( mbedtls_sha512_context *ctx );
 
 /**
  * \brief          This function clones the state of a SHA-512 context.
  *
- * \param dst      The destination context.
- * \param src      The context to clone.
+ * \param dst      The destination context. This must be initialized.
+ * \param src      The context to clone. This must be initialized.
  */
 void mbedtls_sha512_clone( mbedtls_sha512_context *dst,
                            const mbedtls_sha512_context *src );
@@ -94,11 +99,12 @@
  * \brief          This function starts a SHA-384 or SHA-512 checksum
  *                 calculation.
  *
- * \param ctx      The SHA-512 context to initialize.
- * \param is384    Determines which function to use:
- *                 0: Use SHA-512, or 1: Use SHA-384.
+ * \param ctx      The SHA-512 context to use. This must be initialized.
+ * \param is384    Determines which function to use. This must be
+ *                 either \c for SHA-512, or \c 1 for SHA-384.
  *
  * \return         \c 0 on success.
+ * \return         A negative error code on failure.
  */
 int mbedtls_sha512_starts_ret( mbedtls_sha512_context *ctx, int is384 );
 
@@ -106,11 +112,14 @@
  * \brief          This function feeds an input buffer into an ongoing
  *                 SHA-512 checksum calculation.
  *
- * \param ctx      The SHA-512 context.
- * \param input    The buffer holding the input data.
- * \param ilen     The length of the input data.
+ * \param ctx      The SHA-512 context. This must be initialized
+ *                 and have a hash operation started.
+ * \param input    The buffer holding the input data. This must
+ *                 be a readable buffer of length \p ilen Bytes.
+ * \param ilen     The length of the input data in Bytes.
  *
  * \return         \c 0 on success.
+ * \return         A negative error code on failure.
  */
 int mbedtls_sha512_update_ret( mbedtls_sha512_context *ctx,
                     const unsigned char *input,
@@ -121,10 +130,13 @@
  *                 the result to the output buffer. This function is for
  *                 internal use only.
  *
- * \param ctx      The SHA-512 context.
+ * \param ctx      The SHA-512 context. This must be initialized
+ *                 and have a hash operation started.
  * \param output   The SHA-384 or SHA-512 checksum result.
+ *                 This must be a writable buffer of length \c 64 Bytes.
  *
  * \return         \c 0 on success.
+ * \return         A negative error code on failure.
  */
 int mbedtls_sha512_finish_ret( mbedtls_sha512_context *ctx,
                                unsigned char output[64] );
@@ -133,10 +145,12 @@
  * \brief          This function processes a single data block within
  *                 the ongoing SHA-512 computation.
  *
- * \param ctx      The SHA-512 context.
- * \param data     The buffer holding one block of data.
+ * \param ctx      The SHA-512 context. This must be initialized.
+ * \param data     The buffer holding one block of data. This
+ *                 must be a readable buffer of length \c 128 Bytes.
  *
  * \return         \c 0 on success.
+ * \return         A negative error code on failure.
  */
 int mbedtls_internal_sha512_process( mbedtls_sha512_context *ctx,
                                      const unsigned char data[128] );
@@ -152,9 +166,9 @@
  *
  * \deprecated     Superseded by mbedtls_sha512_starts_ret() in 2.7.0
  *
- * \param ctx      The SHA-512 context to initialize.
- * \param is384    Determines which function to use:
- *                 0: Use SHA-512, or 1: Use SHA-384.
+ * \param ctx      The SHA-512 context to use. This must be initialized.
+ * \param is384    Determines which function to use. This must be either
+ *                 \c 0 for SHA-512 or \c 1 for SHA-384.
  */
 MBEDTLS_DEPRECATED void mbedtls_sha512_starts( mbedtls_sha512_context *ctx,
                                                int is384 );
@@ -165,9 +179,11 @@
  *
  * \deprecated     Superseded by mbedtls_sha512_update_ret() in 2.7.0.
  *
- * \param ctx      The SHA-512 context.
- * \param input    The buffer holding the data.
- * \param ilen     The length of the input data.
+ * \param ctx      The SHA-512 context. This must be initialized
+ *                 and have a hash operation started.
+ * \param input    The buffer holding the data. This must be a readable
+ *                 buffer of length \p ilen Bytes.
+ * \param ilen     The length of the input data in Bytes.
  */
 MBEDTLS_DEPRECATED void mbedtls_sha512_update( mbedtls_sha512_context *ctx,
                                                const unsigned char *input,
@@ -179,8 +195,10 @@
  *
  * \deprecated     Superseded by mbedtls_sha512_finish_ret() in 2.7.0.
  *
- * \param ctx      The SHA-512 context.
- * \param output   The SHA-384 or SHA-512 checksum result.
+ * \param ctx      The SHA-512 context. This must be initialized
+ *                 and have a hash operation started.
+ * \param output   The SHA-384 or SHA-512 checksum result. This must
+ *                 be a writable buffer of size \c 64 Bytes.
  */
 MBEDTLS_DEPRECATED void mbedtls_sha512_finish( mbedtls_sha512_context *ctx,
                                                unsigned char output[64] );
@@ -192,8 +210,9 @@
  *
  * \deprecated     Superseded by mbedtls_internal_sha512_process() in 2.7.0.
  *
- * \param ctx      The SHA-512 context.
- * \param data     The buffer holding one block of data.
+ * \param ctx      The SHA-512 context. This must be initialized.
+ * \param data     The buffer holding one block of data. This must be
+ *                 a readable buffer of length \c 128 Bytes.
  */
 MBEDTLS_DEPRECATED void mbedtls_sha512_process(
                                             mbedtls_sha512_context *ctx,
@@ -212,13 +231,16 @@
  *                 The SHA-512 result is calculated as
  *                 output = SHA-512(input buffer).
  *
- * \param input    The buffer holding the input data.
- * \param ilen     The length of the input data.
+ * \param input    The buffer holding the input data. This must be
+ *                 a readable buffer of length \p ilen Bytes.
+ * \param ilen     The length of the input data in Bytes.
  * \param output   The SHA-384 or SHA-512 checksum result.
- * \param is384    Determines which function to use:
- *                 0: Use SHA-512, or 1: Use SHA-384.
+ *                 This must be a writable buffer of length \c 64 Bytes.
+ * \param is384    Determines which function to use. This must be either
+ *                 \c 0 for SHA-512, or \c 1 for SHA-384.
  *
  * \return         \c 0 on success.
+ * \return         A negative error code on failure.
  */
 int mbedtls_sha512_ret( const unsigned char *input,
                         size_t ilen,
@@ -231,6 +253,7 @@
 #else
 #define MBEDTLS_DEPRECATED
 #endif
+
 /**
  * \brief          This function calculates the SHA-512 or SHA-384
  *                 checksum of a buffer.
@@ -243,11 +266,13 @@
  *
  * \deprecated     Superseded by mbedtls_sha512_ret() in 2.7.0
  *
- * \param input    The buffer holding the data.
- * \param ilen     The length of the input data.
- * \param output   The SHA-384 or SHA-512 checksum result.
- * \param is384    Determines which function to use:
- *                 0: Use SHA-512, or 1: Use SHA-384.
+ * \param input    The buffer holding the data. This must be a
+ *                 readable buffer of length \p ilen Bytes.
+ * \param ilen     The length of the input data in Bytes.
+ * \param output   The SHA-384 or SHA-512 checksum result. This must
+ *                 be a writable buffer of length \c 64 Bytes.
+ * \param is384    Determines which function to use. This must be either
+ *                 \c 0 for SHA-512, or \c 1 for SHA-384.
  */
 MBEDTLS_DEPRECATED void mbedtls_sha512( const unsigned char *input,
                                         size_t ilen,
@@ -256,6 +281,9 @@
 
 #undef MBEDTLS_DEPRECATED
 #endif /* !MBEDTLS_DEPRECATED_REMOVED */
+
+#if defined(MBEDTLS_SELF_TEST)
+
  /**
  * \brief          The SHA-384 or SHA-512 checkup routine.
  *
@@ -263,6 +291,7 @@
  * \return         \c 1 on failure.
  */
 int mbedtls_sha512_self_test( int verbose );
+#endif /* MBEDTLS_SELF_TEST */
 
 #ifdef __cplusplus
 }