From f298ea406e4a60062ebc607222fda147375b4407 Mon Sep 17 00:00:00 2001
From: bugobliterator <siddharthbharatpurohit@gmail.com>
Date: Wed, 6 Oct 2021 12:00:38 +0530
Subject: [PATCH] HAL_ChibiOS: enable RNG only for H7 based boards off for the
 rest by default

---
 libraries/AP_HAL_ChibiOS/Util.cpp                       | 4 ++--
 libraries/AP_HAL_ChibiOS/hwdef/common/board.c           | 2 +-
 libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c      | 4 ++--
 libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.h      | 2 +-
 libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py | 7 +++++++
 5 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/libraries/AP_HAL_ChibiOS/Util.cpp b/libraries/AP_HAL_ChibiOS/Util.cpp
index e07b0cbf1b..2b3845d704 100644
--- a/libraries/AP_HAL_ChibiOS/Util.cpp
+++ b/libraries/AP_HAL_ChibiOS/Util.cpp
@@ -610,7 +610,7 @@ void Util::uart_info(ExpandingString &str)
  */
 bool Util::get_random_vals(uint8_t* data, size_t size)
 {
-#ifdef RNG
+#if HAL_USE_HW_RNG && defined(RNG)
     size_t true_random_vals = stm32_rand_generate_nonblocking(data, size);
     if (true_random_vals == size) {
         return true;
@@ -638,7 +638,7 @@ bool Util::get_random_vals(uint8_t* data, size_t size)
  */
 bool Util::get_true_random_vals(uint8_t* data, size_t size, uint32_t timeout_us)
 {
-#ifdef RNG
+#if HAL_USE_HW_RNG && defined(RNG)
     if (stm32_rand_generate_blocking(data, size, timeout_us)) {
         return true;
     } else {
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/board.c b/libraries/AP_HAL_ChibiOS/hwdef/common/board.c
index 41c5513573..c35969a0d6 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/board.c
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/board.c
@@ -255,7 +255,7 @@ void __late_init(void) {
   /*
    * Initialize RNG
    */
-#ifdef RNG
+#if HAL_USE_HW_RNG && defined(RNG)
   rccEnableAHB2(RCC_AHB2ENR_RNGEN, 0);
   RNG->CR |= RNG_CR_IE;
   RNG->CR |= RNG_CR_RNGEN;
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c b/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c
index c6fd964ba8..2682206237 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c
@@ -480,7 +480,7 @@ uint32_t stack_free(void *stack_base)
 }
 #endif
 
-#ifdef RNG
+#if HAL_USE_HW_RNG && defined(RNG)
 static bool stm32_rand_generate(uint32_t *val)
 {
     uint32_t error_bits = 0;
@@ -548,4 +548,4 @@ unsigned int stm32_rand_generate_nonblocking(unsigned char* output, unsigned int
     return i;
 }
 
-#endif // #ifdef RNG
+#endif // #if HAL_USE_HW_RNG && defined(RNG)
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.h b/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.h
index 1936f08b63..eaf5417670 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.h
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.h
@@ -132,7 +132,7 @@ uint32_t stack_free(void *stack_base);
  * Generates a block of random values, returns total values generated
  * if nonblocking, for blocking returns if successful or not
  */
-#ifdef RNG
+#if HAL_USE_HW_RNG && defined(RNG)
 bool stm32_rand_generate_blocking(unsigned char* output, unsigned int sz, uint32_t timeout_us);
 unsigned int stm32_rand_generate_nonblocking(unsigned char* output, unsigned int sz);
 #endif
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
index 76490cf191..deccc30986 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
+++ b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
@@ -737,6 +737,13 @@ def write_mcu_config(f):
         for d in defines.keys():
             v = defines[d]
             f.write("#ifndef %s\n#define %s %s\n#endif\n" % (d, d, v))
+    else:
+        defines = {}
+    # enable RNG for all H7 chips
+    if mcu_series.startswith("STM32H7") and 'HAL_USE_HW_RNG' not in defines.keys():
+        f.write("#define HAL_USE_HW_RNG TRUE\n")
+    elif 'HAL_USE_HW_RNG' not in defines.keys():
+        f.write("#define HAL_USE_HW_RNG FALSE\n")
 
     if get_config('PROCESS_STACK', required=False):
         env_vars['PROCESS_STACK'] = get_config('PROCESS_STACK')