cpu/stm32: add stm32mp1_eng_mode pseudomodule

In Engineering mode (BOOT0 off and BOOT2 on), only the Cortex-M4
core is running. It means that all clocks have to be setup
by the Cortex-M4 core.
In other modes, the clocks are setup by the Cortex-A7 and then should
not be setup by Cortex-M4.
stm32mp1_eng_mode pseudomodule have to be used in Engineering mode
to ensure clocks configuration with IS_USED(MODULE_STM32MP1_ENG_MODE)
macro.
This macro can also be used in periph_conf.h to define clock source
for each peripheral.

Signed-off-by: Gilles DOFFE <gilles.doffe@savoirfairelinux.com>

cpu/stm32/cpu_init.c

@@ -161,8 +161,10 @@ void cpu_init(void)
     defined(CPU_FAM_STM32L1)
     _gpio_init_ain();
 #endif
+#if !defined(CPU_FAM_STM32MP1) || IS_USED(MODULE_STM32MP1_ENG_MODE)
     /* initialize the system clock as configured in the periph_conf.h */
     stmclk_init_sysclk();
+#endif
 #ifdef MODULE_PERIPH_DMA
     /*  initialize DMA streams */
     dma_init();

cpu/stm32/periph/pm.c

@@ -146,7 +146,9 @@ void pm_set(unsigned mode)
 
     if (deep) {
         /* Re-init clock after STOP */
+#if !defined(CPU_FAM_STM32MP1) || IS_USED(MODULE_STM32MP1_ENG_MODE)
         stmclk_init_sysclk();
+#endif
     }
 }
 

cpu/stm32/stmclk/Makefile

@@ -17,7 +17,12 @@ else ifneq (,$(filter $(CPU_FAM),l5))
 else ifneq (,$(filter $(CPU_FAM),g0 g4))
   SRC += stmclk_gx.c
 else ifneq (,$(filter $(CPU_FAM),mp1))
-  SRC = stmclk_mp1.c
+  ifneq (,$(filter stm32mp1_eng_mode,$(USEMODULE)))
+    SRC = stmclk_mp1.c
+  else
+    # Do not use *.c as SRC if SRC is empty (see Makefile.base)
+    NO_AUTO_SRC = 1
+  endif
 endif
 
 include $(RIOTBASE)/Makefile.base

makefiles/pseudomodules.inc.mk

@@ -125,6 +125,7 @@ PSEUDOMODULES += stdio_uart_rx
 PSEUDOMODULES += stm32_eth
 PSEUDOMODULES += stm32_eth_auto
 PSEUDOMODULES += stm32_eth_link_up
+PSEUDOMODULES += stm32mp1_eng_mode
 PSEUDOMODULES += suit_transport_%
 PSEUDOMODULES += suit_storage_%
 PSEUDOMODULES += wakaama_objects_%