Diff: targets/TARGET_TOSHIBA/TARGET_TMPM46B/trng_api.c

Revision:

184:08ed48f1de7f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_TOSHIBA/TARGET_TMPM46B/trng_api.c	Thu Apr 19 17:12:19 2018 +0100
@@ -0,0 +1,98 @@
+/* mbed Microcontroller Library
+ * (C)Copyright TOSHIBA ELECTRONIC DEVICES & STORAGE CORPORATION 2017 All rights reserved
+ *
+ * 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.
+ */
+#include "mbed_error.h"
+#include "tmpm46b_esg.h"
+#include "trng_api.h"
+
+static Result ESG_Config(void)
+{
+    Result ret = ERROR;
+    uint16_t Fintming = 560U;
+
+    // Confirm the ESG core stops
+    if (ESG_GetCalculationStatus() == ESG_CALCULATION_COMPLETE) {
+        // Confirm no interrupt generation
+        if (ESG_GetIntStatus() == DISABLE) {
+            // Set the latch timing & output timing
+            if ((ESG_SetLatchTiming(ESG_LATCH_TIMING_1) == SUCCESS) &&
+                (ESG_SetFintiming(Fintming) == SUCCESS)) {
+                ret = SUCCESS;
+            }
+        }
+    }
+    return ret;
+}
+
+void trng_init(trng_t *obj)
+{
+    // Enable clock supply
+    CG_SetFcPeriphB(CG_FC_PERIPH_ESG, ENABLE);
+    // Initialise ESG core & Start up the ESG core
+    if ((ESG_Config() == SUCCESS) && (ESG_Startup() == SUCCESS)) {
+        obj->trng_init = true;
+    } else {
+        error("TRNG is not Initialised");
+        obj->trng_init = false;
+    }
+}
+
+void trng_free(trng_t *obj)
+{
+    ESG_IPReset();
+    // Disable clock supply
+    CG_SetFcPeriphB(CG_FC_PERIPH_ESG, DISABLE);
+    obj->trng_init = false;
+}
+
+int trng_get_bytes(trng_t *obj, uint8_t *output, size_t length, size_t *output_length)
+{
+    volatile uint8_t random[64] = {0};
+    uint8_t i;
+    Result ret = ERROR;
+
+    *output_length = 0;
+
+    if (!obj->trng_init) {
+        error("TRNG is not Initialised");
+        return FAIL; // fail i.e. -1 
+    }
+
+    while (ESG_GetIntStatus() == DISABLE) {
+        // Wait for ESG core for generating an interrupt
+    }
+    // Interrupt clearing
+    ret = ESG_ClrInt();
+    if (ret == ERROR) {
+        return FAIL; // fail i.e. -1 
+    }
+    // Get the calculation result
+    ESG_GetResult((uint32_t*)random); //512-bit entropy
+
+    for (i = 0; (i < 64) && (i < length); i++) {
+        *output++ = random[i];
+        // clear the buffer
+        random[i] = 0;
+    }
+    *output_length = i;
+    //clear and restart the ESG core
+    ESG_IPReset();
+    ret |= ESG_Startup();
+    if (ret == ERROR) {
+        return FAIL; // fail i.e. -1
+    }
+
+    return ret;
+}