Add GD32 TRNG support

Introduce a new `gd32::trng` wrapper with `Init()` and `Get()` helpers, plus the GD32F20X/GD32F4XX implementation. The new code enables the TRNG peripheral, waits for valid data with timeout handling, and reports clock/seed errors when random data is not ready or repeats.

Author: vanvught

lib-gd32/include/gd32_trng.h

@@ -0,0 +1,40 @@
+/**
+ * @file gd32_trng.h
+ *
+ */
+/* Copyright (C) 2026 by Arjan van Vught mailto:info@gd32-dmx.org
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef GD32_TRNG_H_
+#define GD32_TRNG_H_
+
+#if defined(GD32F10X) || defined(GD32F30X)
+#errror MCU is not supported
+#endif
+
+#include <cstdint>
+
+namespace gd32::trng {
+bool Init();
+bool Get(uint32_t& out);
+} // namespace gd32::trng
+
+#endif // GD32_TRNG_H_

lib-gd32/src/gd32_trng.cpp

@@ -0,0 +1,97 @@
+#if defined(GD32F20X) || defined(GD32F4XX)
+/**
+ * @file gd32_trng.h
+ *
+ */
+/* Copyright (C) 2026 by Arjan van Vught mailto:info@gd32-dmx.org
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#if defined(DEBUG_GD32_TRNG)
+#undef NDEBUG
+#endif
+
+#include <cstdint>
+#include <cstdio>
+
+#include "gd32_trng.h"
+#include "gd32.h" // IWYU pragma: keep
+#include "firmware/debug/debug_debug.h"
+
+namespace gd32::trng {
+static constexpr uint32_t kTimeout = 0xFFFF;
+
+static bool ReadyCheck() {
+    uint32_t timeout = 0;
+    FlagStatus trng_flag = RESET;
+
+    // check wherther the random data is valid
+    do {
+        timeout++;
+        trng_flag = trng_flag_get(TRNG_FLAG_DRDY);
+    } while ((RESET == trng_flag) && (kTimeout > timeout));
+
+    if (RESET == trng_flag) [[unlikely]] {
+        // ready check timeout
+        printf("Error: TRNG can't ready \r\n");
+        trng_flag = trng_flag_get(TRNG_FLAG_CECS);
+        printf("Clock error current status: %d \r\n", trng_flag);
+        trng_flag = trng_flag_get(TRNG_FLAG_SECS);
+        printf("Seed error current status: %d \r\n", trng_flag);
+        return false;
+    }
+
+    return true;
+}
+
+bool Init() {
+    DEBUG_ENTRY();
+
+    // TRNG module clock enable
+    rcu_periph_clock_enable(RCU_TRNG);
+    // TRNG registers reset
+    trng_deinit();
+    trng_enable();
+    // check TRNG work status
+    const auto kReturn= ReadyCheck();
+
+    DEBUG_PRINTF("%s", kReturn ? "Success" : "Error");
+    DEBUG_EXIT();
+    return kReturn;
+}
+
+static uint32_t out_last = 0;
+
+bool Get(uint32_t& out) {
+    if (ReadyCheck()) {
+        out = trng_get_true_random_data();
+        if (out != out_last) {
+            out_last = out;
+            return true;
+        }
+        // the random data is invalid
+        puts("Error: Get the random data is same");
+    }
+
+    return false;
+}
+} // namespace gd32::trng
+
+#endif