Merge pull request #9620 from AaltoNEPPI/feature-refactor-cortex_init

cpu/cortexm_common/cortexm_init: Allow piecewise calling

cpu/cortexm_common/cortexm_init.c

@@ -20,32 +20,19 @@
 
 #include "cpu.h"
 
-/**
- * @name   Pattern to write into the co-processor Access Control Register to
- *         allow full FPU access
- */
-#define FULL_FPU_ACCESS         (0x00f00000)
-
 /**
  * Interrupt vector base address, defined by the linker
  */
 extern const void *_isr_vectors;
 
-void cortexm_init(void)
-{
-    /* initialize the FPU on Cortex-M4F CPUs */
-#if defined(CPU_ARCH_CORTEX_M4F) || defined(CPU_ARCH_CORTEX_M7)
-    /* give full access to the FPU */
-    SCB->CPACR |= (uint32_t)FULL_FPU_ACCESS;
-#endif
-
-    /* configure the vector table location to internal flash */
-#if defined(CPU_ARCH_CORTEX_M3) || defined(CPU_ARCH_CORTEX_M4) || \
-    defined(CPU_ARCH_CORTEX_M4F) || defined(CPU_ARCH_CORTEX_M7) || \
-    (defined(CPU_ARCH_CORTEX_M0PLUS) && (__VTOR_PRESENT == 1))
-    SCB->VTOR = (uint32_t)&_isr_vectors;
+#if defined(CPU_CORTEXM_INIT_SUBFUNCTIONS)
+#define CORTEXM_STATIC_INLINE /*empty*/
+#else
+#define CORTEXM_STATIC_INLINE static inline
 #endif
 
+CORTEXM_STATIC_INLINE void cortexm_init_isr_priorities(void)
+{
     /* initialize the interrupt priorities */
     /* set pendSV interrupt to same priority as the rest */
     NVIC_SetPriority(PendSV_IRQn, CPU_DEFAULT_IRQ_PRIO);
@@ -55,7 +42,10 @@ void cortexm_init(void)
     for (unsigned i = 0; i < CPU_IRQ_NUMOF; i++) {
         NVIC_SetPriority((IRQn_Type) i, CPU_DEFAULT_IRQ_PRIO);
     }
+}
 
+CORTEXM_STATIC_INLINE void cortexm_init_misc(void)
+{
     /* enable wake up on events for __WFE CPU sleep */
     SCB->SCR |= SCB_SCR_SEVONPEND_Msk;
 
@@ -67,3 +57,18 @@ void cortexm_init(void)
     SCB->CCR |= SCB_CCR_STKALIGN_Msk;
 #endif
 }
+
+void cortexm_init(void)
+{
+    cortexm_init_fpu();
+
+    /* configure the vector table location to internal flash */
+#if defined(CPU_ARCH_CORTEX_M3) || defined(CPU_ARCH_CORTEX_M4) || \
+    defined(CPU_ARCH_CORTEX_M4F) || defined(CPU_ARCH_CORTEX_M7) || \
+    (defined(CPU_ARCH_CORTEX_M0PLUS) && (__VTOR_PRESENT == 1))
+    SCB->VTOR = (uint32_t)&_isr_vectors;
+#endif
+
+    cortexm_init_isr_priorities();
+    cortexm_init_misc();
+}

cpu/cortexm_common/include/cpu.h

@@ -58,6 +58,14 @@ extern "C" {
  */
 #define PROVIDES_PM_SET_LOWEST
 
+/**
+ * @brief   Pattern to write into the co-processor Access Control Register to
+ *          allow full FPU access
+ *
+ * Used in the @ref cortexm_init_fpu inline function below.
+ */
+#define CORTEXM_SCB_CPACR_FPU_ACCESS_FULL         (0x00f00000)
+
 /**
  * @brief   Initialization of the CPU
  */
@@ -65,9 +73,64 @@ void cpu_init(void);
 
 /**
  * @brief   Initialize Cortex-M specific core parts of the CPU
+ *
+ * @ref cortexm_init calls, in a default order, @ref cortexm_init_fpu,
+ * @ref cortexm_init_isr_priorities, and @ref cortexm_init_misc.  Also
+ * performs other default initialisations, including ones which you
+ * may or may not want.
+ *
+ * Unless you have special requirements (like nRF52 with SD has), it
+ * is sufficient to call just @ref cortexm_init and the `cortexm_init_*`
+ * functions do not need to (and should not) be called separately.
+ * If you have conflicting requirements, you may want to have a look
+ * `cpu/nrft/cpu.c` for an example of a non-default approach.
  */
 void cortexm_init(void);
 
+/**
+ * @brief   Initialize Cortex-M FPU
+ *
+ * Called from `cpu/nrf52/cpu.c`, since it cannot use the
+ * whole @ref cortexm_init due to conflicting requirements.
+ *
+ * Defined here as a static inline function to allow all
+ * callers to optimise this away if the FPU is not used.
+ */
+static inline void cortexm_init_fpu(void)
+{
+    /* initialize the FPU on Cortex-M4F CPUs */
+#if defined(CPU_ARCH_CORTEX_M4F) || defined(CPU_ARCH_CORTEX_M7)
+    /* give full access to the FPU */
+    SCB->CPACR |= (uint32_t)CORTEXM_SCB_CPACR_FPU_ACCESS_FULL;
+#endif
+}
+
+#if defined(CPU_CORTEXM_INIT_SUBFUNCTIONS) || defined(DOXYGEN)
+
+/**
+ * @brief   Initialize Cortex-M interrupt priorities
+ *
+ * Called from `cpu/nrf52/cpu.c`, since it cannot use the
+ * whole @ref cortexm_init due to conflicting requirements.
+ *
+ * Define `CPU_CORTEXM_INIT_SUBFUNCTIONS` to make this function
+ * publicly available.
+ */
+void cortexm_init_isr_priorities(void);
+
+/**
+ * @brief   Initialize Cortex-M misc functions
+ *
+ * Called from `cpu/nrf52/cpu.c`, since it cannot use the
+ * whole @ref cortexm_init due to conflicting requirements.
+ *
+ * Define `CPU_CORTEXM_INIT_SUBFUNCTIONS` to make this function
+ * publicly available.
+ */
+void cortexm_init_misc(void);
+
+#endif /* defined(CPU_CORTEXM_INIT_SUBFUNCTIONS) || defined(DOXYGEN) */
+
 /**
  * @brief   Prints the current content of the link register (lr)
  */