Fix some documentation typos/markup/duplication.

include/mbedtls/aes.h

@@ -121,14 +121,14 @@ typedef struct mbedtls_aes_xts_context
  *                 It must be the first API called before using
  *                 the context.
  *
- * \param ctx      The AES context to initialize. Must not be NULL.
+ * \param ctx      The AES context to initialize. Must not be \c NULL.
  */
 void mbedtls_aes_init( mbedtls_aes_context *ctx );
 
 /**
  * \brief          This function releases and clears the specified AES context.
  *
- * \param ctx      The AES context to clear. If NULL, no action is taken.
+ * \param ctx      The AES context to clear. If \c NULL, no action is taken.
  */
 void mbedtls_aes_free( mbedtls_aes_context *ctx );
 
@@ -139,14 +139,14 @@ void mbedtls_aes_free( mbedtls_aes_context *ctx );
  *                 It must be the first API called before using
  *                 the context.
  *
- * \param ctx      The AES XTS context to initialize. Must not be NULL.
+ * \param ctx      The AES XTS context to initialize. Must not be \c NULL.
  */
 void mbedtls_aes_xts_init( mbedtls_aes_xts_context *ctx );
 
 /**
  * \brief          This function releases and clears the specified AES XTS context.
  *
- * \param ctx      The AES XTS context to clear. If NULL, no action is taken.
+ * \param ctx      The AES XTS context to clear. If \c NULL, no action is taken.
  */
 void mbedtls_aes_xts_free( mbedtls_aes_xts_context *ctx );
 #endif /* MBEDTLS_CIPHER_MODE_XTS */
@@ -155,8 +155,8 @@ void mbedtls_aes_xts_free( mbedtls_aes_xts_context *ctx );
  * \brief          This function sets the encryption key.
  *
  * \param ctx      The AES context to which the key should be bound. Must not
- *                 be NULL.
+ *                 be \c NULL.
- * \param key      The encryption key. Must not be NULL.
+ * \param key      The encryption key. Must not be \c NULL.
  * \param keybits  The size of data passed in bits. Valid options are:
  *                 <ul><li>128 bits</li>
  *                 <li>192 bits</li>
@@ -172,8 +172,8 @@ int mbedtls_aes_setkey_enc( mbedtls_aes_context *ctx, const unsigned char *key,
  * \brief          This function sets the decryption key.
  *
  * \param ctx      The AES context to which the key should be bound. Must not
- *                 be NULL.
+ *                 be \c NULL.
- * \param key      The decryption key. Must not be NULL.
+ * \param key      The decryption key. Must not be \c NULL.
  * \param keybits  The size of data passed. Valid options are:
  *                 <ul><li>128 bits</li>
  *                 <li>192 bits</li>

include/mbedtls/config.h

@@ -3040,16 +3040,16 @@
 /**
  * \brief       This macro is invoked by the library when an invalid parameter
  *              is detected that is only checked with MBEDTLS_CHECK_PARAMS
- *              (see the document of the flag for context).
+ *              (see the documentation of that option for context).
  *
  *              When you leave this undefined here, a default definition is
- *              provided the invokes the function mbedtls_param_failed(),
+ *              provided that invokes the function mbedtls_param_failed(),
  *              which is declared in platform_util.h for the benefit of the
  *              library, but that you need to define in your application.
  *
  *              When you define this here, this replaces the default
  *              definition in platform_util.h (which no longer declares the
- *              function mbedtls_param_failed()) and it is your responsability
+ *              function mbedtls_param_failed()) and it is your responsibility
  *              to make sure this macro expands to something suitable (in
  *              particular, that all the necessary declarations are visible
  *              from within the library).

include/mbedtls/platform_util.h

@@ -56,18 +56,10 @@ extern "C" {
 
 /**
  * \brief       User supplied callback function for parameter validation failure.
- *
+ *              See #MBEDTLS_CHECK_PARAMS for context.
- *              When the MBEDTLS_CHECK_PARAMS option is enabled, the library
- *              provides additional validation of all input parameters to
- *              confirm that they conform to what the interface can accept.
- *              For example - NULL paramater checks.
- *
- *              These checks are designed to check programmatic issues in the
- *              application software using Mbed TLS, or catch other runtime
- *              errors which may be due to issues in the application software.
  *
  *              This function will be called unless an alternative treatement
- *              is defined through the MBEDTLS_PARAM_FAILED() macro.
+ *              is defined through the #MBEDTLS_PARAM_FAILED macro.
  *
  *              This function can return, and the operation will be aborted, or
  *              alternatively, through use of setjmp()/longjmp() can resume