Nuvoton: Remove TRNG support

These targets below just support PRNG, not real TRNG. They cannot annouce TRNG.

-   NUMAKER_PFM_NUC472
-   NUMAKER_PFM_M487
-   NUMAKER_IOT_M487

On targets without TRNG, to run mbedtls applications which require entropy source,
there are two alternatives to TRNG:

-   Custom entropy source:
    Define MBEDTLS_ENTROPY_HARDWARE_ALT and provide custom mbedtls_hardware_poll(...)
-   NV seed:
    1.  Define MBEDTLS_ENTROPY_NV_SEED
    2.  Define MBEDTLS_PLATFORM_NV_SEED_READ_MACRO/MBEDTLS_PLATFORM_NV_SEED_WRITE_MACRO and provide custom mbedtls_nv_seed_read(...)/mbedtls_nv_seed_write(...).
    3.  Don't define MBEDTLS_PSA_INJECT_ENTROPY. Meet mbedtls_psa_inject_entropy(...) undefined and then provide custom one, which must be compatible with mbedtls_nv_seed_read(...)/mbedtls_nv_seed_write(...) above.
    4.  For development, simulating partial provision process, inject entropy seed via mbedtls_psa_inject_entropy(...) pre-main.

targets/TARGET_NUVOTON/TARGET_M480/objects.h

@@ -1,5 +1,5 @@
 /* mbed Microcontroller Library
- * Copyright (c) 2015-2016 Nuvoton
+ * Copyright (c) 2015-2019 Nuvoton
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -118,10 +118,6 @@ struct pwmout_s {
     uint32_t pulsewidth_us;
 };
 
-struct trng_s {
-    uint8_t dummy;
-};
-
 struct can_s {
     CANName can;
     PinName pin_rd;

targets/TARGET_NUVOTON/TARGET_M480/trng_api.c

@@ -1,88 +0,0 @@
-/* mbed Microcontroller Library
- * Copyright (c) 2015-2016 Nuvoton
- *
- * 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.
- */
-
-#if DEVICE_TRNG
-
-#include <stdlib.h>
-#include <string.h>
-#include "cmsis.h"
-#include "us_ticker_api.h"
-#include "trng_api.h"
-#include "crypto-misc.h"
-
-/*
- * Get Random number generator.
- */
-
-#define PRNG_KEY_SIZE  (0x20UL)
-
-static void trng_get(unsigned char *pConversionData)
-{
-    uint32_t *p32ConversionData;
-
-    p32ConversionData = (uint32_t *)pConversionData;
-
-    PRNG_Open(PRNG_KEY_SIZE_256, 1, us_ticker_read());
-    crypto_prng_prestart();
-    PRNG_Start();
-    crypto_prng_wait();
-
-    PRNG_Read(p32ConversionData);
-}
-
-void trng_init(trng_t *obj)
-{
-    (void)obj;
-    
-    /* Init crypto module */
-    crypto_init();
-    
-    PRNG_ENABLE_INT();
-}
-
-void trng_free(trng_t *obj)
-{
-    (void)obj;
-    
-    PRNG_DISABLE_INT();
-    
-    /* Uninit crypto module */
-    crypto_uninit();
-}
-
-int trng_get_bytes(trng_t *obj, uint8_t *output, size_t length, size_t *output_length)
-{
-    (void)obj;
-    unsigned char tmpBuff[PRNG_KEY_SIZE];
-    size_t cur_length = 0;
-    
-    while (length >= sizeof(tmpBuff)) {
-        trng_get(output);
-        output += sizeof(tmpBuff);
-        cur_length += sizeof(tmpBuff);
-        length -= sizeof(tmpBuff);
-    }
-    if (length > 0) {
-        trng_get(tmpBuff);
-        memcpy(output, tmpBuff, length);
-        cur_length += length;
-        crypto_zeroize(tmpBuff, sizeof(tmpBuff));
-    }
-    *output_length = cur_length;
-    return 0;
-}
-
-#endif

targets/TARGET_NUVOTON/TARGET_NUC472/objects.h

@@ -1,5 +1,5 @@
 /* mbed Microcontroller Library
- * Copyright (c) 2015-2016 Nuvoton
+ * Copyright (c) 2015-2019 Nuvoton
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -114,10 +114,6 @@ struct pwmout_s {
     uint32_t pulsewidth_us;
 };
 
-struct trng_s {
-    uint8_t dummy;
-};
-
 struct can_s {
 	CANName can;
     PinName pin_rd;

targets/TARGET_NUVOTON/TARGET_NUC472/trng_api.c

@@ -1,92 +0,0 @@
-/*
- *  Hardware entropy collector for NUC472's RNGA
- *
- *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
- *  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.
- *
- */
-
-#if DEVICE_TRNG
-
-#include <stdlib.h>
-#include <string.h>
-#include "cmsis.h"
-#include "us_ticker_api.h"
-#include "trng_api.h"
-#include "crypto-misc.h"
-
-/*
- * Get Random number generator.
- */
-
-#define PRNG_KEY_SIZE  (0x20UL)
-
-static void trng_get(unsigned char *pConversionData)
-{
-    uint32_t *p32ConversionData;
-
-    p32ConversionData = (uint32_t *)pConversionData;
-
-    PRNG_Open(PRNG_KEY_SIZE_256, 1, us_ticker_read());
-    crypto_prng_prestart();
-    PRNG_Start();
-    crypto_prng_wait();
-
-    PRNG_Read(p32ConversionData);
-}
-
-void trng_init(trng_t *obj)
-{
-    (void)obj;
-    
-    /* Init crypto module */
-    crypto_init();
-    
-    PRNG_ENABLE_INT();
-}
-
-void trng_free(trng_t *obj)
-{
-    (void)obj;
-    
-    PRNG_DISABLE_INT();
-    
-    /* Uninit crypto module */
-    crypto_uninit();
-}
-
-int trng_get_bytes(trng_t *obj, uint8_t *output, size_t length, size_t *output_length)
-{
-    (void)obj;
-    unsigned char tmpBuff[PRNG_KEY_SIZE];
-    size_t cur_length = 0;
-    
-    while (length >= sizeof(tmpBuff)) {
-        trng_get(output);
-        output += sizeof(tmpBuff);
-        cur_length += sizeof(tmpBuff);
-        length -= sizeof(tmpBuff);
-    }
-    if (length > 0) {
-        trng_get(tmpBuff);
-        memcpy(output, tmpBuff, length);
-        cur_length += length;
-        crypto_zeroize(tmpBuff, sizeof(tmpBuff));
-    }
-    *output_length = cur_length;
-    return 0;
-}
-
-#endif

targets/targets.json

@@ -7980,7 +7980,6 @@
             "SPI",
             "SPISLAVE",
             "SPI_ASYNCH",
-            "TRNG",
             "CAN",
             "FLASH",
             "EMAC",
@@ -8629,7 +8628,6 @@
             "SPI",
             "SPISLAVE",
             "SPI_ASYNCH",
-            "TRNG",
             "FLASH",
             "CAN",
             "EMAC",