hw/mcu/stm32: Add option to place WFI in RAM

Some STM32 devices have erratas for flash related
issues that recommend workaround of placing WFI
instruction in RAM.
This is the case for STM32F4xx devices where other
solution was to put WFI instruction at specific
address locations (divisible by 8).

New syscfg value STM32_WFI_FROM_RAM is introduced that
adds function stm32_wfi_from_ram().

STM32_WFI is also added and can be used instead
of WFI when needed

BSP for affected STM32F4xx devices now use WFI from RAM
instead of placing WFI instruction at aligne address.
STM32L0 devices are also updated since anomally was also
observed there.

Signed-off-by: Jerzy Kasenberg <jerzy@apache.org>

hw/bsp/ada_feather_stm32f405/syscfg.yml

@@ -48,6 +48,7 @@ syscfg.vals:
  STM32_FLASH_PREFETCH_ENABLE: 1
  STM32_INSTRUCTION_CACHE_ENABLE: 1
  STM32_DATA_CACHE_ENABLE: 1
+ STM32_WFI_FROM_RAM: 1
  WATCHDOG_INTERVAL: 28000
  # UART0 is on the large breakout connector, pins TX and RX.
  UART_0_PIN_TX: 'MCU_GPIO_PORTB(10)'

hw/bsp/b-l072z-lrwan1/syscfg.yml

@@ -51,6 +51,7 @@ syscfg.vals:
  STM32_CLOCK_APB2_DIVIDER: 'RCC_HCLK_DIV1'
  STM32_FLASH_LATENCY: 1 # max 32MHz
  STM32_FLASH_PREFETCH_ENABLE: 0
+ STM32_WFI_FROM_RAM: 1
  WATCHDOG_INTERVAL: 25000
  UART_0_PIN_TX: 'MCU_GPIO_PORTA(2)'
  UART_0_PIN_RX: 'MCU_GPIO_PORTA(3)'

hw/bsp/black_vet6/syscfg.yml

@@ -64,6 +64,7 @@ syscfg.vals:
  STM32_FLASH_PREFETCH_ENABLE: 1
  STM32_INSTRUCTION_CACHE_ENABLE: 1
  STM32_DATA_CACHE_ENABLE: 1
+ STM32_WFI_FROM_RAM: 1
  WATCHDOG_INTERVAL: 25000
 
  SPI_0_MASTER: 1

hw/bsp/nucleo-l073rz/syscfg.yml

@@ -57,6 +57,7 @@ syscfg.vals:
  STM32_CLOCK_APB2_DIVIDER: 'RCC_HCLK_DIV1'
  STM32_FLASH_LATENCY: 1 # max 32MHz
  STM32_FLASH_PREFETCH_ENABLE: 0
+ STM32_WFI_FROM_RAM: 1
  WATCHDOG_INTERVAL: 25000
  UART_0_PIN_TX: 'MCU_GPIO_PORTA(2)'
  UART_0_PIN_RX: 'MCU_GPIO_PORTA(3)'

hw/bsp/olimex_stm32-e407_devboard/syscfg.yml

@@ -48,6 +48,7 @@ syscfg.vals:
  STM32_FLASH_PREFETCH_ENABLE: 1
  STM32_INSTRUCTION_CACHE_ENABLE: 1
  STM32_DATA_CACHE_ENABLE: 1
+ STM32_WFI_FROM_RAM: 1
  WATCHDOG_INTERVAL: 28000
  UART_0_PIN_TX: 'MCU_GPIO_PORTC(6)'
  UART_0_PIN_RX: 'MCU_GPIO_PORTC(7)'

hw/mcu/stm/stm32_common/include/stm32_common/mcu.h

@@ -108,6 +108,13 @@ extern "C" {
 
 void stm32_start_bootloader(void);
 
+#if MYNEWT_VAL_STM32_WFI_FROM_RAM
+extern void stm32_wfi_from_ram(void);
+#define STM32_WFI stm32_wfi_from_ram
+#else
+#define STM32_WFI __WFI
+#endif
+
 #ifdef __cplusplus
 }
 #endif

hw/mcu/stm/stm32_common/src/hal_os_tick.c

@@ -18,41 +18,32 @@
  */
 
 #include <assert.h>
-#include "os/mynewt.h"
+#include <os/mynewt.h>
+#include <stm32_common/mcu.h>
 #include <hal/hal_os_tick.h>
 
 #if MYNEWT_VAL(OS_TICKS_USE_RTC)
 #include <stm32_common/stm32_hal.h>
 #include <datetime/datetime.h>
 #endif
 
+#if MYNEWT_VAL(STM32_WFI_FROM_RAM)
+__attribute__((section(".text_ram"))) void
+stm32_wfi_from_ram(void)
+{
+ __ASM volatile("wfi\n"
+ "bx lr");
+}
+#endif
+
 /*
  * ST's MCUs seems to have problem with accessing AHB interface from SWD during SLEEP.
  * This makes it almost impossible to use with SEGGER SystemView, therefore when OS_SYSVIEW
  * is defined __WFI will become a loop waiting for pending interrupts.
  */
 #if MYNEWT_VAL(OS_SYSVIEW)
-#undef __WFI
-#define __WFI() do { } while ((SCB->ICSR & (SCB_ICSR_ISRPENDING_Msk | SCB_ICSR_PENDSTSET_Msk)) == 0)
-#else
-/*
- * Errata for STM32F405, STM32F407, STM32F415, STM32F417.
- * When WFI instruction is placed at address like 0x080xxxx4
- * (also seen for addresses ending with xxx2). System may
- * crash.
- * __WFI function places WFI instruction at address ending with x0 or x8
- * for affected MCUs.
- */
-#if defined(STM32F405xx) || defined(STM32F407xx) || \
- defined(STM32F415xx) || defined(STM32F417xx)
-#undef __WFI
-__attribute__((aligned(8), naked)) void static
-__WFI(void)
-{
- __ASM volatile("wfi\n"
- "bx lr");
-}
-#endif
+#undef STM32_WFI
+#define STM32_WFI() do { } while ((SCB->ICSR & (SCB_ICSR_ISRPENDING_Msk | SCB_ICSR_PENDSTSET_Msk)) == 0)
 #endif
 
 #if MYNEWT_VAL(OS_TICKS_USE_RTC)
@@ -219,7 +210,7 @@ os_tick_idle(os_time_t ticks)
  }
 
  __DSB();
- __WFI();
+ STM32_WFI();
 
  if (ticks > 0) {
  rtc_update_time();
@@ -389,7 +380,7 @@ os_tick_idle(os_time_t ticks)
 {
  OS_ASSERT_CRITICAL();
  __DSB();
- __WFI();
+ STM32_WFI();
 }
 
 void

hw/mcu/stm/stm32_common/syscfg.yml

@@ -466,5 +466,11 @@ syscfg.defs:
  When enabled, OS_TICKS_PER_SEC should be one of 128, 256, 512, 1024.
  value: 0
 
+ STM32_WFI_FROM_RAM:
+ description: >
+ Place WFI instruction in RAM instead of flash.
+ This may be needed for several MCU's including STM32F40x.
+ value:
+
 syscfg.vals:
  OS_TICKS_PER_SEC: 1000