diff --git a/ports/stm32f4/common-hal/busio/SPI.c b/ports/stm32f4/common-hal/busio/SPI.c
index e20bd7a947..b5517f470f 100644
--- a/ports/stm32f4/common-hal/busio/SPI.c
+++ b/ports/stm32f4/common-hal/busio/SPI.c
@@ -36,46 +36,37 @@
 #include "supervisor/shared/translate.h"
 #include "common-hal/microcontroller/Pin.h"
 
-STATIC bool reserved_spi[6];
-STATIC bool never_reset_spi[6];
+#define MAX_SPI 6 //TODO; replace this as part of periph cleanup
+#define ALL_CLOCKS 0xFF
 
-void spi_reset(void) {
-    #ifdef SPI1
-    if(!never_reset_spi[0]) {
-        reserved_spi[0] = false;
-        __HAL_RCC_SPI1_CLK_DISABLE(); 
-    }
-    #endif
+//arrays use 0 based numbering: SPI1 is stored at index 0
+STATIC bool reserved_spi[MAX_SPI];
+STATIC bool never_reset_spi[MAX_SPI];
+
+STATIC void spi_clock_enable(uint8_t mask);
+STATIC void spi_clock_disable(uint8_t mask);
+
+STATIC uint32_t get_busclock(SPI_TypeDef * instance) {
+    //SPI2 and 3 are on PCLK1, if they exist. 
     #ifdef SPI2
-    if(!never_reset_spi[1]) {
-        reserved_spi[1] = false;
-        __HAL_RCC_SPI2_CLK_DISABLE(); 
-    }
+        if(instance == SPI2) return HAL_RCC_GetPCLK1Freq();
     #endif
     #ifdef SPI3
-    if(!never_reset_spi[2]) {
-        reserved_spi[2] = false;
-        __HAL_RCC_SPI3_CLK_DISABLE(); 
+        if(instance == SPI3) return HAL_RCC_GetPCLK1Freq();
+    #endif
+    return HAL_RCC_GetPCLK2Freq();
+}
+
+void spi_reset(void) {
+    uint16_t never_reset_mask = 0x00;
+    for(int i=0;i<MAX_SPI;i++) {
+        if (!never_reset_spi[i]) {
+            reserved_spi[i] = 0x00;
+        } else {
+            never_reset_mask |= 1<<i;
+        }
     }
-    #endif
-    #ifdef SPI4
-    if(!never_reset_spi[3]) {
-        reserved_spi[3] = false;
-        __HAL_RCC_SPI4_CLK_DISABLE();
-    } 
-    #endif
-    #ifdef SPI5
-    if(!never_reset_spi[4]) {
-        reserved_spi[4] = false;
-        __HAL_RCC_SPI5_CLK_DISABLE();
-    } 
-    #endif
-    #ifdef SPI6
-    if(!never_reset_spi[5]) {
-        reserved_spi[5] = false;
-        __HAL_RCC_SPI6_CLK_DISABLE(); 
-    }
-    #endif
+    spi_clock_disable(ALL_CLOCKS & ~(never_reset_mask));
 }
 
 void common_hal_busio_spi_construct(busio_spi_obj_t *self,
@@ -152,42 +143,8 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
     GPIO_InitStruct.Alternate = self->miso->altfn_index; 
     HAL_GPIO_Init(pin_port(miso->port), &GPIO_InitStruct);
 
-    #ifdef SPI1
-    if(SPIx==SPI1) { 
-        reserved_spi[0] = true;
-        __HAL_RCC_SPI1_CLK_ENABLE();
-    } 
-    #endif
-    #ifdef SPI2
-    if(SPIx==SPI2) { 
-        reserved_spi[1] = true;
-        __HAL_RCC_SPI2_CLK_ENABLE();
-    } 
-    #endif
-    #ifdef SPI3
-    if(SPIx==SPI3) { 
-        reserved_spi[2] = true;
-        __HAL_RCC_SPI3_CLK_ENABLE();
-    } 
-    #endif
-    #ifdef SPI4
-    if(SPIx==SPI4) { 
-        reserved_spi[3] = true;
-        __HAL_RCC_SPI4_CLK_ENABLE();
-    } 
-    #endif
-    #ifdef SPI5
-    if(SPIx==SPI5) { 
-        reserved_spi[4] = true;
-        __HAL_RCC_SPI5_CLK_ENABLE();
-    } 
-    #endif
-    #ifdef SPI6
-    if(SPIx==SPI6) { 
-        reserved_spi[5] = true;
-        __HAL_RCC_SPI6_CLK_ENABLE();
-    } 
-    #endif
+    spi_clock_enable(1<<(self->sck->spi_index - 1));
+    reserved_spi[self->sck->spi_index - 1] = true;
     
     self->handle.Instance = SPIx; 
     self->handle.Init.Mode = SPI_MODE_MASTER;
@@ -205,7 +162,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
     {
         mp_raise_ValueError(translate("SPI Init Error"));
     }
-    self->baudrate = (HAL_RCC_GetPCLK2Freq()/16);
+    self->baudrate = (get_busclock(SPIx)/16);
     self->prescaler = 16;
     self->polarity = 0;
     self->phase = 1;
@@ -233,42 +190,9 @@ bool common_hal_busio_spi_deinited(busio_spi_obj_t *self) {
 }
 
 void common_hal_busio_spi_deinit(busio_spi_obj_t *self) {
-    #ifdef SPI1
-    if(self->handle.Instance==SPI1) {
-        reserved_spi[0] = false;
-        __HAL_RCC_SPI1_CLK_DISABLE(); 
-    }
-    #endif
-    #ifdef SPI2
-    if(self->handle.Instance==SPI2) {
-        reserved_spi[1] = false;
-        __HAL_RCC_SPI2_CLK_DISABLE(); 
-    }
-    #endif
-    #ifdef SPI3
-    if(self->handle.Instance==SPI3) {
-        reserved_spi[2] = false;
-        __HAL_RCC_SPI3_CLK_DISABLE(); 
-    }
-    #endif
-    #ifdef SPI4
-    if(self->handle.Instance==SPI4) {
-        reserved_spi[3] = false;
-        __HAL_RCC_SPI4_CLK_DISABLE(); 
-    }
-    #endif
-    #ifdef SPI5
-    if(self->handle.Instance==SPI5) {
-        reserved_spi[4] = false;
-        __HAL_RCC_SPI5_CLK_DISABLE(); 
-    }
-    #endif
-    #ifdef SPI6
-    if(self->handle.Instance==SPI6) {
-        reserved_spi[5] = false;
-        __HAL_RCC_SPI6_CLK_DISABLE(); 
-    }
-    #endif
+    spi_clock_disable(1<<(self->sck->spi_index - 1));
+    reserved_spi[self->sck->spi_index - 1] = true;
+
     reset_pin_number(self->sck->pin->port,self->sck->pin->number);
     reset_pin_number(self->mosi->pin->port,self->mosi->pin->number);
     reset_pin_number(self->miso->pin->port,self->miso->pin->number);
@@ -277,7 +201,7 @@ void common_hal_busio_spi_deinit(busio_spi_obj_t *self) {
     self->miso = mp_const_none;
 }
 
-static uint32_t stm32_baud_to_spi_div(uint32_t baudrate, uint16_t * prescaler) {
+STATIC uint32_t stm32_baud_to_spi_div(uint32_t baudrate, uint16_t * prescaler, uint32_t busclock) {
     static const uint32_t baud_map[8][2] = {
         {2,SPI_BAUDRATEPRESCALER_2},
         {4,SPI_BAUDRATEPRESCALER_4},
@@ -292,7 +216,7 @@ static uint32_t stm32_baud_to_spi_div(uint32_t baudrate, uint16_t * prescaler) {
     uint16_t divisor;
     do {
         divisor = baud_map[i][0];
-        if (baudrate >= (HAL_RCC_GetPCLK2Freq()/divisor)) {
+        if (baudrate >= (busclock/divisor)) {
             *prescaler = divisor;
             return baud_map[i][1];
         }
@@ -312,28 +236,12 @@ bool common_hal_busio_spi_configure(busio_spi_obj_t *self,
     //Deinit SPI
     HAL_SPI_DeInit(&self->handle);
 
-    if (bits == 8) {
-        self->handle.Init.DataSize = SPI_DATASIZE_8BIT;
-    } else if (bits == 16) {
-        self->handle.Init.DataSize = SPI_DATASIZE_16BIT;
-    } else {
-        return false;
-    }
-
-    if (polarity) {
-        self->handle.Init.CLKPolarity = SPI_POLARITY_HIGH;
-    } else {
-        self->handle.Init.CLKPolarity = SPI_POLARITY_LOW;
-    }
-
-    if (phase) {
-        self->handle.Init.CLKPhase = SPI_PHASE_2EDGE;
-    } else {
-        self->handle.Init.CLKPhase = SPI_PHASE_1EDGE;
-    }
-
-    self->handle.Init.BaudRatePrescaler = stm32_baud_to_spi_div(baudrate, &self->prescaler);
+    self->handle.Init.DataSize = (bits == 16) ? SPI_DATASIZE_16BIT : SPI_DATASIZE_8BIT;
+    self->handle.Init.CLKPolarity = (polarity) ? SPI_POLARITY_HIGH : SPI_POLARITY_LOW;
+    self->handle.Init.CLKPhase = (phase) ? SPI_PHASE_2EDGE : SPI_PHASE_1EDGE;
 
+    self->handle.Init.BaudRatePrescaler = stm32_baud_to_spi_div(baudrate, &self->prescaler, 
+                                            get_busclock(self->handle.Instance));
     self->handle.Init.Mode = SPI_MODE_MASTER;
     self->handle.Init.Direction = SPI_DIRECTION_2LINES;
     self->handle.Init.NSS = SPI_NSS_SOFT;
@@ -362,10 +270,10 @@ bool common_hal_busio_spi_try_lock(busio_spi_obj_t *self) {
     // __disable_irq();
     // __DMB();
 
-        if (!self->has_lock) {
-            grabbed_lock = true;
-            self->has_lock = true;
-        }
+    if (!self->has_lock) {
+        grabbed_lock = true;
+        self->has_lock = true;
+    }
 
     // __DMB();
     // __set_PRIMASK(store_primask);
@@ -412,4 +320,46 @@ uint8_t common_hal_busio_spi_get_phase(busio_spi_obj_t* self) {
 
 uint8_t common_hal_busio_spi_get_polarity(busio_spi_obj_t* self) {
     return self->polarity;
-}
\ No newline at end of file
+}
+
+STATIC void spi_clock_enable(uint8_t mask) {
+    #ifdef SPI1
+    if (mask & 1<<0) __HAL_RCC_SPI1_CLK_ENABLE();
+    #endif
+    #ifdef SPI2
+    if (mask & 1<<1) __HAL_RCC_SPI2_CLK_ENABLE();
+    #endif
+    #ifdef SPI3
+    if (mask & 1<<2) __HAL_RCC_SPI3_CLK_ENABLE();
+    #endif
+    #ifdef SPI4
+    if (mask & 1<<3) __HAL_RCC_SPI4_CLK_ENABLE();
+    #endif
+    #ifdef SPI5
+    if (mask & 1<<4) __HAL_RCC_SPI5_CLK_ENABLE();
+    #endif
+    #ifdef SPI6
+    if (mask & 1<<5) __HAL_RCC_SPI6_CLK_ENABLE();
+    #endif
+}
+
+STATIC void spi_clock_disable(uint8_t mask) {
+    #ifdef SPI1
+    if (mask & 1<<0) __HAL_RCC_SPI1_CLK_DISABLE();
+    #endif
+    #ifdef SPI2
+    if (mask & 1<<1) __HAL_RCC_SPI2_CLK_DISABLE();
+    #endif
+    #ifdef SPI3
+    if (mask & 1<<2) __HAL_RCC_SPI3_CLK_DISABLE();
+    #endif
+    #ifdef SPI4
+    if (mask & 1<<3) __HAL_RCC_SPI4_CLK_DISABLE();
+    #endif
+    #ifdef SPI5
+    if (mask & 1<<4) __HAL_RCC_SPI5_CLK_DISABLE();
+    #endif
+    #ifdef SPI6
+    if (mask & 1<<5) __HAL_RCC_SPI6_CLK_DISABLE();
+    #endif
+}