STM32: Fix I2C repeated start by converting to IT mode

ports/stm/common-hal/busio/I2C.c

@@ -61,6 +61,7 @@ STATIC bool never_reset_i2c[MAX_I2C];
 #define ALL_CLOCKS 0xFF
 STATIC void i2c_clock_enable(uint8_t mask);
 STATIC void i2c_clock_disable(uint8_t mask);
+STATIC void i2c_assign_irq(busio_i2c_obj_t *self, I2C_TypeDef * I2Cx);
 
 void i2c_reset(void) {
     uint16_t never_reset_mask = 0x00;
@@ -136,6 +137,10 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
     i2c_clock_enable(1 << (self->sda->periph_index - 1));
     reserved_i2c[self->sda->periph_index - 1] = true;
 
+    // Create root pointer and assign IRQ
+    MP_STATE_PORT(cpy_i2c_obj_all)[self->sda->periph_index - 1] = self;
+    i2c_assign_irq(self, I2Cx);
+
     // Handle the HAL handle differences
     #if (CPY_STM32H7 || CPY_STM32F7)
     if (frequency == 400000) {
@@ -163,6 +168,13 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
     }
     common_hal_mcu_pin_claim(sda);
     common_hal_mcu_pin_claim(scl);
+
+    self->frame_in_prog = false;
+
+    //start the receive interrupt chain
+    HAL_NVIC_DisableIRQ(self->irq); //prevent handle lock contention
+    HAL_NVIC_SetPriority(self->irq, 1, 0);
+    HAL_NVIC_EnableIRQ(self->irq);
 }
 
 void common_hal_busio_i2c_never_reset(busio_i2c_obj_t *self) {
@@ -229,15 +241,46 @@ void common_hal_busio_i2c_unlock(busio_i2c_obj_t *self) {
 
 uint8_t common_hal_busio_i2c_write(busio_i2c_obj_t *self, uint16_t addr,
                                    const uint8_t *data, size_t len, bool transmit_stop_bit) {
-    HAL_StatusTypeDef result = HAL_I2C_Master_Transmit(&(self->handle), (uint16_t)(addr << 1),
+    HAL_StatusTypeDef result;
+    if (!transmit_stop_bit) {
+        uint32_t xfer_opt;
+        if (!self->frame_in_prog) {
+            xfer_opt = I2C_FIRST_FRAME;
+        } else {
+            // handle rare possibility of multiple restart writes in a row
+            xfer_opt = I2C_NEXT_FRAME;
+        }
+        result = HAL_I2C_Master_Seq_Transmit_IT(&(self->handle),
+                                    (uint16_t)(addr << 1), (uint8_t *)data,
+                                    (uint16_t)len, xfer_opt);
+        while (HAL_I2C_GetState(&(self->handle)) != HAL_I2C_STATE_READY)
+        {
+            RUN_BACKGROUND_TASKS;
+        }
+        self->frame_in_prog = true;
+    } else {
+        result = HAL_I2C_Master_Transmit(&(self->handle), (uint16_t)(addr << 1),
                                                         (uint8_t *)data, (uint16_t)len, 500);
+    }
     return result == HAL_OK ? 0 : MP_EIO;
 }
 
 uint8_t common_hal_busio_i2c_read(busio_i2c_obj_t *self, uint16_t addr,
         uint8_t *data, size_t len) {
-    return HAL_I2C_Master_Receive(&(self->handle), (uint16_t)(addr<<1), data, (uint16_t)len, 500)
+    if (!self->frame_in_prog) {
+        return HAL_I2C_Master_Receive(&(self->handle), (uint16_t)(addr<<1), data, (uint16_t)len, 500)
                                     == HAL_OK ? 0 : MP_EIO;
+    } else {
+        HAL_StatusTypeDef result = HAL_I2C_Master_Seq_Receive_IT(&(self->handle),
+                                    (uint16_t)(addr << 1), (uint8_t *)data,
+                                    (uint16_t)len, I2C_LAST_FRAME);
+        while (HAL_I2C_GetState(&(self->handle)) != HAL_I2C_STATE_READY)
+        {
+            RUN_BACKGROUND_TASKS;
+        }
+        self->frame_in_prog = false;
+        return result;
+    }
 }
 
 STATIC void i2c_clock_enable(uint8_t mask) {
@@ -294,3 +337,48 @@ STATIC void i2c_clock_disable(uint8_t mask) {
     }
     #endif
 }
+
+STATIC void i2c_assign_irq(busio_i2c_obj_t *self, I2C_TypeDef * I2Cx) {
+    #ifdef I2C1
+    if (I2Cx == I2C1) {
+        self->irq = I2C1_EV_IRQn;
+    }
+    #endif
+    #ifdef I2C2
+    if (I2Cx == I2C2) {
+        self->irq = I2C2_EV_IRQn;
+    }
+    #endif
+    #ifdef I2C3
+    if (I2Cx == I2C3) {
+        self->irq = I2C3_EV_IRQn;
+    }
+    #endif
+    #ifdef I2C4
+    if (I2Cx == I2C4) {
+        self->irq = I2C4_EV_IRQn;
+    }
+    #endif
+}
+
+STATIC void call_hal_irq(int i2c_num) {
+    //Create casted context pointer
+    busio_i2c_obj_t * context = (busio_i2c_obj_t*)MP_STATE_PORT(cpy_i2c_obj_all)[i2c_num - 1];
+    if (context != NULL) {
+        HAL_NVIC_ClearPendingIRQ(context->irq);
+        HAL_I2C_EV_IRQHandler(&context->handle);
+    }
+}
+
+void I2C1_EV_IRQHandler(void) {
+    call_hal_irq(1);
+}
+void I2C2_EV_IRQHandler(void) {
+    call_hal_irq(2);
+}
+void I2C3_EV_IRQHandler(void) {
+    call_hal_irq(3);
+}
+void I2C4_EV_IRQHandler(void) {
+    call_hal_irq(4);
+}

ports/stm/common-hal/busio/I2C.h

@@ -37,6 +37,8 @@
 typedef struct {
     mp_obj_base_t base;
     I2C_HandleTypeDef handle;
+    IRQn_Type irq;
+    bool frame_in_prog;
     bool has_lock;
     const mcu_periph_obj_t *scl;
     const mcu_periph_obj_t *sda;

ports/stm/mpconfigport.h

@@ -52,10 +52,14 @@ extern uint8_t _ld_default_stack_size;
 #define BOARD_NO_VBUS_SENSE (0)
 #endif
 
-#define MAX_UART 10 //how many UART are implemented
+// Peripheral implementation counts
+#define MAX_UART 10
+#define MAX_I2C 4
+#define MAX_SPI 6
 
 #define MICROPY_PORT_ROOT_POINTERS \
     void *cpy_uart_obj_all[MAX_UART]; \
+    void *cpy_i2c_obj_all[MAX_I2C]; \
 	CIRCUITPY_COMMON_ROOT_POINTERS
 
 #endif  // __INCLUDED_MPCONFIGPORT_H