From 243cf2199d367d2647aa752ce3a7c269b2df6292 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Tue, 23 Feb 2021 15:07:53 +1100
Subject: [PATCH] HAL_ChibiOS: disable shared DMA on IOMCU

this saves about 600 bytes of ram
---
 libraries/AP_HAL_ChibiOS/HAL_ChibiOS_Class.cpp     | 3 +++
 libraries/AP_HAL_ChibiOS/RCOutput.cpp              | 2 ++
 libraries/AP_HAL_ChibiOS/Util.cpp                  | 2 ++
 libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c | 1 -
 libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat     | 1 +
 libraries/AP_HAL_ChibiOS/shared_dma.cpp            | 3 ++-
 libraries/AP_HAL_ChibiOS/shared_dma.h              | 4 ++++
 7 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/libraries/AP_HAL_ChibiOS/HAL_ChibiOS_Class.cpp b/libraries/AP_HAL_ChibiOS/HAL_ChibiOS_Class.cpp
index acfcefde71..91e928f6ab 100644
--- a/libraries/AP_HAL_ChibiOS/HAL_ChibiOS_Class.cpp
+++ b/libraries/AP_HAL_ChibiOS/HAL_ChibiOS_Class.cpp
@@ -192,7 +192,10 @@ static void main_loop()
     ChibiOS::I2CBus::clear_all();
 #endif
 
+#ifndef HAL_NO_SHARED_DMA
     ChibiOS::Shared_DMA::init();
+#endif
+
     peripheral_power_enable();
 
     hal.serial(0)->begin(115200);
diff --git a/libraries/AP_HAL_ChibiOS/RCOutput.cpp b/libraries/AP_HAL_ChibiOS/RCOutput.cpp
index 40da4eb60a..1a22accf54 100644
--- a/libraries/AP_HAL_ChibiOS/RCOutput.cpp
+++ b/libraries/AP_HAL_ChibiOS/RCOutput.cpp
@@ -154,6 +154,7 @@ void RCOutput::rcout_thread()
     }
 }
 
+#ifndef HAL_NO_SHARED_DMA
 // release locks on the groups that are pending in reverse order
 void RCOutput::dshot_collect_dma_locks(uint32_t last_run_us)
 {
@@ -192,6 +193,7 @@ void RCOutput::dshot_collect_dma_locks(uint32_t last_run_us)
         }
     }
 }
+#endif // HAL_NO_SHARED_DMA
 
 /*
   setup the output frequency for a group and start pwm output
diff --git a/libraries/AP_HAL_ChibiOS/Util.cpp b/libraries/AP_HAL_ChibiOS/Util.cpp
index c24a128afd..cb88434669 100644
--- a/libraries/AP_HAL_ChibiOS/Util.cpp
+++ b/libraries/AP_HAL_ChibiOS/Util.cpp
@@ -375,7 +375,9 @@ void Util::thread_info(ExpandingString &str)
 // request information on dma contention
 void Util::dma_info(ExpandingString &str)
 {
+#ifndef HAL_NO_SHARED_DMA
     ChibiOS::Shared_DMA::dma_info(str);
+#endif
 }
 #endif
 
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c b/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c
index 44997c02b4..a75bef595d 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/stm32_util.c
@@ -276,7 +276,6 @@ void set_rtc_backup(uint8_t idx, const uint32_t *v, uint8_t n)
 // get RTC backup registers starting at given idx
 void get_rtc_backup(uint8_t idx, uint32_t *v, uint8_t n)
 {
-    return 0;
 }
 #endif // NO_FASTBOOT
 
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat
index ffbb9dbbd7..0c97ca4013 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat
@@ -120,6 +120,7 @@ define HAL_NO_TIMER_THREAD
 define HAL_NO_RCIN_THREAD
 define HAL_NO_MONITOR_THREAD
 define HAL_NO_RCOUT_THREAD
+define HAL_NO_SHARED_DMA
 
 #defined to turn off undef warnings
 define __FPU_PRESENT 0
diff --git a/libraries/AP_HAL_ChibiOS/shared_dma.cpp b/libraries/AP_HAL_ChibiOS/shared_dma.cpp
index 68c5c11caa..6a631a3900 100644
--- a/libraries/AP_HAL_ChibiOS/shared_dma.cpp
+++ b/libraries/AP_HAL_ChibiOS/shared_dma.cpp
@@ -20,7 +20,7 @@
   code to handle sharing of DMA channels between peripherals
  */
 
-#if CH_CFG_USE_MUTEXES == TRUE
+#if CH_CFG_USE_MUTEXES == TRUE && !defined(HAL_NO_SHARED_DMA)
 
 #include <AP_Common/ExpandingString.h>
 
@@ -267,3 +267,4 @@ void Shared_DMA::dma_info(ExpandingString &str)
 }
 
 #endif // CH_CFG_USE_SEMAPHORES
+
diff --git a/libraries/AP_HAL_ChibiOS/shared_dma.h b/libraries/AP_HAL_ChibiOS/shared_dma.h
index c987a370b3..f408cf7b56 100644
--- a/libraries/AP_HAL_ChibiOS/shared_dma.h
+++ b/libraries/AP_HAL_ChibiOS/shared_dma.h
@@ -23,6 +23,8 @@
 // DMA stream ID for stream_id2 when only one is needed
 #define SHARED_DMA_NONE 255
 
+#ifndef HAL_NO_SHARED_DMA
+
 class ChibiOS::Shared_DMA
 {
 public:
@@ -108,3 +110,5 @@ private:
         uint32_t transactions;
     } *_contention_stats;
 };
+
+#endif // HAL_NO_SHARED_DMA