[stm32] Adapt startup code and clock configuration for H7 dual-core

Author: chris-durand

src/modm/platform/clock/stm32/rcc.cpp.in

@@ -529,4 +529,22 @@ Rcc::setCanPrescaler(CanPrescaler prescaler)
 }
 %% endif
 
+%% if target.family == "h7" and target.name in ["45", "47", "55", "57"] and target.core == "m7"
+void
+Rcc::bootCortexM4()
+{
+	// Enable Cortex-M4 boot in case it is disabled via option bytes
+	RCC->GCR |= RCC_GCR_BOOT_C2;
+
+	// Lock hardware semaphore 0
+	// Cortex-M4 startup code will continue to boot
+	RCC->AHB4ENR |= RCC_AHB4ENR_HSEMEN_Msk;
+	constexpr unsigned CortexM7CoreId{3};
+	HSEM->R[0] = HSEM_R_LOCK | (CortexM7CoreId << HSEM_R_COREID_Pos);
+
+	// Wait for unlock by Cortex-M4 core
+	while((HSEM->R[0] & HSEM_R_LOCK) != 0);
+}
+%% endif
+
 }

src/modm/platform/clock/stm32/rcc.hpp.in

@@ -865,6 +865,17 @@ public:
 	setVoltageScaling(VoltageScaling voltage, uint32_t waitCycles = 2048);
 %% endif
 
+%% if target.family == "h7" and target.name in ["45", "47", "55", "57"] and target.core == "m7"
+	/**
+	 * Release lock in Cortex-M4 startup code to continue boot. Call this function
+	 * after system initialization has been completed.
+	 *
+	 * In case automatic Cortex-M4 boot is disabled in the option bytes, the core will
+	 * be enabled.
+	 */
+	static void bootCortexM4();
+%% endif
+
 public:
 	/** Set flash latency for CPU frequency and voltage.
 	 * Does nothing if CPU frequency is too high for the available

src/modm/platform/clock/systick/module.lb

@@ -36,7 +36,8 @@ def build(env):
     # Interrupt Frequency must not overflow the 2^24 SysTick->VAL!
     freq = 1000 if "m0" in core else 4
     # STM32H7 goes up to 550MHz, so make the Frequency higher
-    if target.family == "h7": freq = 100;
+    if target.family == "h7" and target.get("core", "cm7") == "cm7":
+        freq = 100
 
     # SysTick clock prescaler is dynamically chosen as /1 or /8
     div = 8

src/modm/platform/core/stm32/startup_platform.c.in

@@ -28,6 +28,17 @@
 void
 __modm_initialize_platform(void)
 {
+%% if target.family == "h7" and target.name in ["45", "47", "55", "57"] and target.core == "m4"
+	/* Use hardware semaphore 0 as a spin lock to delay Cortex-M4 boot until
+	 * the system has been initialized by the Cortex-M7 core */
+	RCC->AHB4ENR |= RCC_AHB4ENR_HSEMEN_Msk;
+	// wait until hardware semaphore 0 has been locked by Cortex-M7
+	while((HSEM->R[0] & HSEM_R_LOCK) == 0);
+	// unlock hardware semaphore
+	const unsigned CortexM7CoreId = 3;
+	HSEM->CR = HSEM->KEYR | (CortexM7CoreId << HSEM_CR_COREID_Pos);
+%% endif
+
 	// Enable SYSCFG
 %% if target.family == "g0"
 	RCC->APBENR2 |= RCC_APBENR2_SYSCFGEN;

src/modm/platform/gpio/stm32/enable.cpp.in

@@ -59,4 +59,6 @@ modm_gpio_enable(void)
 %% endfor
 }
 
+%% if not (target.family == "h7" and target.name in ["45", "47", "55", "57"] and target.core == "m4")
 MODM_HARDWARE_INIT_ORDER(modm_gpio_enable, 80);
+%% endif