stm32/can: Refactor can.h API to not depend on pyboard can types.

This is necessary for the machine.CAN implementation to use the same
low-level functions.

Includes some refactoring around FIFO selection as there was a footgun
where CAN_FIFO0/1 are 0/1 but FDCAN_RX_FIFO0/1 are not. Added an explicit
type for non-hardware-specific FIFO numbering.

Also moved responsibility for re-enabling CAN receive interrupts into the
higher layer (pyb_can.c layer) after calling can_receive().

Also includes this behaviour change for FDCAN boards:

- Fix for boards with FDCAN not updating error status
  counters (num_error_warning, num_error_passive, num_bus_off). These are
  now updated the same as on boards with CAN Classic controllers, as
  documented.

- Previously FDCAN boards would trigger the RX callback function on error
  events instead (passing undocumented irq numbers 3, 4, 5).
  This behaviour has been removed in favour of the documented behaviour of
  updating the status counters.

This work was funded through GitHub Sponsors.

Signed-off-by: Angus Gratton <angus@redyak.com.au>

Author: projectgus

ports/stm32/can.c

@@ -28,29 +28,15 @@
 #include "py/mperrno.h"
 #include "py/mphal.h"
 #include "can.h"
+#include "pyb_can.h"
 #include "irq.h"
 
 #if MICROPY_HW_ENABLE_CAN
 
-void can_init0(void) {
-    for (uint i = 0; i < MP_ARRAY_SIZE(MP_STATE_PORT(pyb_can_obj_all)); i++) {
-        MP_STATE_PORT(pyb_can_obj_all)[i] = NULL;
-    }
-}
-
-void can_deinit_all(void) {
-    for (int i = 0; i < MP_ARRAY_SIZE(MP_STATE_PORT(pyb_can_obj_all)); i++) {
-        pyb_can_obj_t *can_obj = MP_STATE_PORT(pyb_can_obj_all)[i];
-        if (can_obj != NULL) {
-            can_deinit(can_obj);
-        }
-    }
-}
-
 #if !MICROPY_HW_ENABLE_FDCAN
 
-bool can_init(pyb_can_obj_t *can_obj, uint32_t mode, uint32_t prescaler, uint32_t sjw, uint32_t bs1, uint32_t bs2, bool auto_restart) {
-    CAN_InitTypeDef *init = &can_obj->can.Init;
+bool can_init(CAN_HandleTypeDef *can, int can_id, uint32_t mode, uint32_t prescaler, uint32_t sjw, uint32_t bs1, uint32_t bs2, bool auto_restart) {
+    CAN_InitTypeDef *init = &can->Init;
     init->Mode = mode << 4; // shift-left so modes fit in a small-int
     init->Prescaler = prescaler;
     init->SJW = ((sjw - 1) & 3) << 24;
@@ -67,7 +53,7 @@ bool can_init(pyb_can_obj_t *can_obj, uint32_t mode, uint32_t prescaler, uint32_
     uint32_t sce_irq = 0;
     const machine_pin_obj_t *pins[2];
 
-    switch (can_obj->can_id) {
+    switch (can_id) {
         #if defined(MICROPY_HW_CAN1_TX)
         case PYB_CAN_1:
             CANx = CAN1;
@@ -107,40 +93,34 @@ bool can_init(pyb_can_obj_t *can_obj, uint32_t mode, uint32_t prescaler, uint32_
     uint32_t pin_mode = MP_HAL_PIN_MODE_ALT;
     uint32_t pin_pull = MP_HAL_PIN_PULL_UP;
     for (int i = 0; i < 2; i++) {
-        if (!mp_hal_pin_config_alt(pins[i], pin_mode, pin_pull, AF_FN_CAN, can_obj->can_id)) {
+        if (!mp_hal_pin_config_alt(pins[i], pin_mode, pin_pull, AF_FN_CAN, can_id)) {
             return false;
         }
     }
 
     // init CANx
-    can_obj->can.Instance = CANx;
-    HAL_CAN_Init(&can_obj->can);
+    can->Instance = CANx;
+    HAL_CAN_Init(can);
 
-    can_obj->is_enabled = true;
-    can_obj->num_error_warning = 0;
-    can_obj->num_error_passive = 0;
-    can_obj->num_bus_off = 0;
-
-    __HAL_CAN_ENABLE_IT(&can_obj->can, CAN_IT_ERR | CAN_IT_BOF | CAN_IT_EPV | CAN_IT_EWG);
+    __HAL_CAN_ENABLE_IT(can, CAN_IT_ERR | CAN_IT_BOF | CAN_IT_EPV | CAN_IT_EWG);
 
     NVIC_SetPriority(sce_irq, IRQ_PRI_CAN);
     HAL_NVIC_EnableIRQ(sce_irq);
 
     return true;
 }
 
-void can_deinit(pyb_can_obj_t *self) {
-    self->is_enabled = false;
-    HAL_CAN_DeInit(&self->can);
-    if (self->can.Instance == CAN1) {
+void can_deinit(CAN_HandleTypeDef *can) {
+    HAL_CAN_DeInit(can);
+    if (can->Instance == CAN1) {
         HAL_NVIC_DisableIRQ(CAN1_RX0_IRQn);
         HAL_NVIC_DisableIRQ(CAN1_RX1_IRQn);
         HAL_NVIC_DisableIRQ(CAN1_SCE_IRQn);
         __HAL_RCC_CAN1_FORCE_RESET();
         __HAL_RCC_CAN1_RELEASE_RESET();
         __HAL_RCC_CAN1_CLK_DISABLE();
     #if defined(CAN2)
-    } else if (self->can.Instance == CAN2) {
+    } else if (can->Instance == CAN2) {
         HAL_NVIC_DisableIRQ(CAN2_RX0_IRQn);
         HAL_NVIC_DisableIRQ(CAN2_RX1_IRQn);
         HAL_NVIC_DisableIRQ(CAN2_SCE_IRQn);
@@ -149,7 +129,7 @@ void can_deinit(pyb_can_obj_t *self) {
         __HAL_RCC_CAN2_CLK_DISABLE();
     #endif
     #if defined(CAN3)
-    } else if (self->can.Instance == CAN3) {
+    } else if (can->Instance == CAN3) {
         HAL_NVIC_DisableIRQ(CAN3_RX0_IRQn);
         HAL_NVIC_DisableIRQ(CAN3_RX1_IRQn);
         HAL_NVIC_DisableIRQ(CAN3_SCE_IRQn);
@@ -160,26 +140,38 @@ void can_deinit(pyb_can_obj_t *self) {
     }
 }
 
-void can_clearfilter(pyb_can_obj_t *self, uint32_t f, uint8_t bank) {
+void can_disable_rx_interrupts(CAN_HandleTypeDef *can, can_rx_fifo_t fifo) {
+    __HAL_CAN_DISABLE_IT(can, ((fifo == CAN_RX_FIFO0) ?
+        (CAN_IT_FMP0 | CAN_IT_FF0 | CAN_IT_FOV0) :
+        (CAN_IT_FMP1 | CAN_IT_FF1 | CAN_IT_FOV1)));
+}
+
+void can_enable_rx_interrupts(CAN_HandleTypeDef *can, can_rx_fifo_t fifo, bool enable_msg_received) {
+    __HAL_CAN_ENABLE_IT(can, ((fifo == CAN_RX_FIFO0) ?
+        ((enable_msg_received ? CAN_IT_FMP0 : 0) | CAN_IT_FF0 | CAN_IT_FOV0) :
+        ((enable_msg_received ? CAN_IT_FMP1 : 0) | CAN_IT_FF1 | CAN_IT_FOV1)));
+}
+
+void can_clearfilter(CAN_HandleTypeDef *can, uint32_t filter_num, uint8_t bank) {
     CAN_FilterConfTypeDef filter;
 
     filter.FilterIdHigh = 0;
     filter.FilterIdLow = 0;
     filter.FilterMaskIdHigh = 0;
     filter.FilterMaskIdLow = 0;
     filter.FilterFIFOAssignment = CAN_FILTER_FIFO0;
-    filter.FilterNumber = f;
+    filter.FilterNumber = filter_num;
     filter.FilterMode = CAN_FILTERMODE_IDMASK;
     filter.FilterScale = CAN_FILTERSCALE_16BIT;
     filter.FilterActivation = DISABLE;
     filter.BankNumber = bank;
 
-    HAL_CAN_ConfigFilter(&self->can, &filter);
+    HAL_CAN_ConfigFilter(can, &filter);
 }
 
-int can_receive(CAN_HandleTypeDef *can, int fifo, CanRxMsgTypeDef *msg, uint8_t *data, uint32_t timeout_ms) {
+int can_receive(CAN_HandleTypeDef *can, can_rx_fifo_t fifo, CanRxMsgTypeDef *msg, uint8_t *data, uint32_t timeout_ms) {
     volatile uint32_t *rfr;
-    if (fifo == CAN_FIFO0) {
+    if (fifo == CAN_RX_FIFO0) {
         rfr = &can->Instance->RF0R;
     } else {
         rfr = &can->Instance->RF1R;
@@ -222,13 +214,16 @@ int can_receive(CAN_HandleTypeDef *can, int fifo, CanRxMsgTypeDef *msg, uint8_t
     return 0; // success
 }
 
-// We have our own version of CAN transmit so we can handle Timeout=0 correctly.
-HAL_StatusTypeDef CAN_Transmit(CAN_HandleTypeDef *hcan, uint32_t Timeout) {
+// Lightly modified version of HAL CAN_Transmit to handle Timeout=0 correctly
+HAL_StatusTypeDef can_transmit(CAN_HandleTypeDef *hcan, CanTxMsgTypeDef *txmsg, uint8_t *data, uint32_t Timeout) {
     uint32_t transmitmailbox;
     uint32_t tickstart;
     uint32_t rqcpflag = 0;
     uint32_t txokflag = 0;
 
+    hcan->pTxMsg = txmsg;
+    (void)data; // Not needed here, caller has set it up as &tx_msg->Data
+
     // Check the parameters
     assert_param(IS_CAN_IDTYPE(hcan->pTxMsg->IDE));
     assert_param(IS_CAN_RTR(hcan->pTxMsg->RTR));
@@ -312,119 +307,130 @@ HAL_StatusTypeDef CAN_Transmit(CAN_HandleTypeDef *hcan, uint32_t Timeout) {
     }
 }
 
-static void can_rx_irq_handler(uint can_id, uint fifo_id) {
-    mp_obj_t callback;
-    pyb_can_obj_t *self;
-    mp_obj_t irq_reason = MP_OBJ_NEW_SMALL_INT(0);
-    byte *state;
-
-    self = MP_STATE_PORT(pyb_can_obj_all)[can_id - 1];
-
-    if (fifo_id == CAN_FIFO0) {
-        callback = self->rxcallback0;
-        state = &self->rx_state0;
+// Workaround for the __HAL_CAN macros expecting a CAN_HandleTypeDef which we
+// don't have in the ISR. Using this "fake" struct instead of CAN_HandleTypeDef
+// so it's not possible to accidentally call an API that uses one of the other
+// fields in the structure.
+typedef struct {
+    CAN_TypeDef *Instance;
+} fake_handle_t;
+
+static void can_rx_irq_handler(uint can_id, CAN_TypeDef *instance, can_rx_fifo_t fifo) {
+    uint32_t full_flag, full_int, overrun_flag, overrun_int, pending_int;
+
+    const fake_handle_t handle = {
+        .Instance = instance,
+    };
+
+    if (fifo == CAN_RX_FIFO0) {
+        full_flag = CAN_FLAG_FF0;
+        full_int = CAN_IT_FF0;
+        overrun_flag = CAN_FLAG_FOV0;
+        overrun_int = CAN_IT_FOV0;
+        pending_int = CAN_IT_FMP0;
     } else {
-        callback = self->rxcallback1;
-        state = &self->rx_state1;
+        full_flag = CAN_FLAG_FF1;
+        full_int = CAN_IT_FF1;
+        overrun_flag = CAN_FLAG_FOV1;
+        overrun_int = CAN_IT_FOV1;
+        pending_int = CAN_IT_FMP1;
     }
 
-    switch (*state) {
-        case RX_STATE_FIFO_EMPTY:
-            __HAL_CAN_DISABLE_IT(&self->can,  (fifo_id == CAN_FIFO0) ? CAN_IT_FMP0 : CAN_IT_FMP1);
-            irq_reason = MP_OBJ_NEW_SMALL_INT(0);
-            *state = RX_STATE_MESSAGE_PENDING;
-            break;
-        case RX_STATE_MESSAGE_PENDING:
-            __HAL_CAN_DISABLE_IT(&self->can, (fifo_id == CAN_FIFO0) ? CAN_IT_FF0 : CAN_IT_FF1);
-            __HAL_CAN_CLEAR_FLAG(&self->can, (fifo_id == CAN_FIFO0) ? CAN_FLAG_FF0 : CAN_FLAG_FF1);
-            irq_reason = MP_OBJ_NEW_SMALL_INT(1);
-            *state = RX_STATE_FIFO_FULL;
-            break;
-        case RX_STATE_FIFO_FULL:
-            __HAL_CAN_DISABLE_IT(&self->can, (fifo_id == CAN_FIFO0) ? CAN_IT_FOV0 : CAN_IT_FOV1);
-            __HAL_CAN_CLEAR_FLAG(&self->can, (fifo_id == CAN_FIFO0) ? CAN_FLAG_FOV0 : CAN_FLAG_FOV1);
-            irq_reason = MP_OBJ_NEW_SMALL_INT(2);
-            *state = RX_STATE_FIFO_OVERFLOW;
-            break;
-        case RX_STATE_FIFO_OVERFLOW:
-            // This should never happen
-            break;
+    bool full = __HAL_CAN_GET_FLAG(&handle, full_flag);
+    bool overrun = __HAL_CAN_GET_FLAG(&handle, overrun_flag);
+
+    // Note: receive interrupt bits are disabled below, and re-enabled by the
+    // higher layer after calling can_receive()
+
+    if (full) {
+        __HAL_CAN_DISABLE_IT(&handle, full_int);
+        __HAL_CAN_CLEAR_FLAG(&handle, full_flag);
+        if (!overrun) {
+            can_irq_handler(can_id, CAN_INT_FIFO_FULL, fifo);
+        }
+    }
+    if (overrun) {
+        __HAL_CAN_DISABLE_IT(&handle, overrun_int);
+        __HAL_CAN_CLEAR_FLAG(&handle, overrun_flag);
+        can_irq_handler(can_id, CAN_INT_FIFO_OVERFLOW, fifo);
     }
 
-    pyb_can_handle_callback(self, fifo_id, callback, irq_reason);
+    if (!(full || overrun)) {
+        // Process of elimination, if neither of the above
+        // FIFO status flags are set then message pending interrupt is what fired.
+        __HAL_CAN_DISABLE_IT(&handle, pending_int);
+        can_irq_handler(can_id, CAN_INT_MESSAGE_RECEIVED, fifo);
+    }
 }
 
-static void can_sce_irq_handler(uint can_id) {
-    pyb_can_obj_t *self = MP_STATE_PORT(pyb_can_obj_all)[can_id - 1];
-    if (self) {
-        self->can.Instance->MSR = CAN_MSR_ERRI;
-        uint32_t esr = self->can.Instance->ESR;
-        if (esr & CAN_ESR_BOFF) {
-            ++self->num_bus_off;
-        } else if (esr & CAN_ESR_EPVF) {
-            ++self->num_error_passive;
-        } else if (esr & CAN_ESR_EWGF) {
-            ++self->num_error_warning;
-        }
+static void can_sce_irq_handler(uint can_id, CAN_TypeDef *instance) {
+    instance->MSR = CAN_MSR_ERRI; // Write to clear ERRIE interrupt
+    uint32_t esr = instance->ESR;
+    if (esr & CAN_ESR_BOFF) {
+        can_irq_handler(can_id, CAN_INT_ERR_BUS_OFF, 0);
+    } else if (esr & CAN_ESR_EPVF) {
+        can_irq_handler(can_id, CAN_INT_ERR_PASSIVE, 0);
+    } else if (esr & CAN_ESR_EWGF) {
+        can_irq_handler(can_id, CAN_INT_ERR_WARNING, 0);
     }
 }
 
 #if defined(MICROPY_HW_CAN1_TX)
 void CAN1_RX0_IRQHandler(void) {
     IRQ_ENTER(CAN1_RX0_IRQn);
-    can_rx_irq_handler(PYB_CAN_1, CAN_FIFO0);
+    can_rx_irq_handler(PYB_CAN_1, CAN1, CAN_RX_FIFO0);
     IRQ_EXIT(CAN1_RX0_IRQn);
 }
 
 void CAN1_RX1_IRQHandler(void) {
     IRQ_ENTER(CAN1_RX1_IRQn);
-    can_rx_irq_handler(PYB_CAN_1, CAN_FIFO1);
+    can_rx_irq_handler(PYB_CAN_1, CAN1, CAN_RX_FIFO1);
     IRQ_EXIT(CAN1_RX1_IRQn);
 }
 
 void CAN1_SCE_IRQHandler(void) {
     IRQ_ENTER(CAN1_SCE_IRQn);
-    can_sce_irq_handler(PYB_CAN_1);
+    can_sce_irq_handler(PYB_CAN_1, CAN1);
     IRQ_EXIT(CAN1_SCE_IRQn);
 }
 #endif
 
 #if defined(MICROPY_HW_CAN2_TX)
 void CAN2_RX0_IRQHandler(void) {
     IRQ_ENTER(CAN2_RX0_IRQn);
-    can_rx_irq_handler(PYB_CAN_2, CAN_FIFO0);
+    can_rx_irq_handler(PYB_CAN_2, CAN2, CAN_RX_FIFO0);
     IRQ_EXIT(CAN2_RX0_IRQn);
 }
 
 void CAN2_RX1_IRQHandler(void) {
     IRQ_ENTER(CAN2_RX1_IRQn);
-    can_rx_irq_handler(PYB_CAN_2, CAN_FIFO1);
+    can_rx_irq_handler(PYB_CAN_2, CAN2, CAN_RX_FIFO1);
     IRQ_EXIT(CAN2_RX1_IRQn);
 }
 
 void CAN2_SCE_IRQHandler(void) {
     IRQ_ENTER(CAN2_SCE_IRQn);
-    can_sce_irq_handler(PYB_CAN_2);
+    can_sce_irq_handler(PYB_CAN_2, CAN2);
     IRQ_EXIT(CAN2_SCE_IRQn);
 }
 #endif
 
 #if defined(MICROPY_HW_CAN3_TX)
 void CAN3_RX0_IRQHandler(void) {
     IRQ_ENTER(CAN3_RX0_IRQn);
-    can_rx_irq_handler(PYB_CAN_3, CAN_FIFO0);
+    can_rx_irq_handler(PYB_CAN_3, CAN3, CAN_RX_FIFO0);
     IRQ_EXIT(CAN3_RX0_IRQn);
 }
 
 void CAN3_RX1_IRQHandler(void) {
     IRQ_ENTER(CAN3_RX1_IRQn);
-    can_rx_irq_handler(PYB_CAN_3, CAN_FIFO1);
+    can_rx_irq_handler(PYB_CAN_3, CAN3, CAN_RX_FIFO1);
     IRQ_EXIT(CAN3_RX1_IRQn);
 }
 
 void CAN3_SCE_IRQHandler(void) {
     IRQ_ENTER(CAN3_SCE_IRQn);
-    can_sce_irq_handler(PYB_CAN_3);
+    can_sce_irq_handler(PYB_CAN_3, CAN3);
     IRQ_EXIT(CAN3_SCE_IRQn);
 }
 #endif