net: can: Added a helper function to adjust the Data Length Code of a…

… CAN-FD frame. Signed-off-by: Adrien Ricciardi <aricciardi@baylibre.com>
TrampolineRTOS · Oct 6, 2023 · 4161018 · 4161018
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commit 4161018
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diff --git a/net/can/Can.h b/net/can/Can.h
@@ -89,4 +89,19 @@ Std_ReturnType Can_SetBaudrate(uint8 Controller, uint16 BaudRateConfigID);
  */
 Std_ReturnType Can_Write(Can_HwHandleType Hth, const Can_PduType *PduInfo);
 
+/**
+ * Convert a CAN-FD payload size in bytes to the corresponding CAN Data Length
+ * Code.
+ *
+ * @param length The payload length in bytes.
+ * @param adjusted_length If not NULL, contain on output the payload adjusted
+ * length in bytes.
+ *
+ * @retval 0 if the provided payload length exceeds 64 bytes,
+ * @retval The DLC code if the provided payload length is valid.
+ *
+ * @note See https://www.can-cia.org/can-knowledge/can/can-fd for more details.
+ */
+uint32 tpl_can_adjust_dlc(uint32 length, uint32 *adjusted_length);
+
 #endif
diff --git a/net/can/Can_GeneralTypes.h b/net/can/Can_GeneralTypes.h
@@ -38,6 +38,9 @@
 #define TPL_CAN_ID_TYPE_GET(id) ((id & TPL_CAN_ID_TYPE_MASK) >> 30)
 #define TPL_CAN_ID_MASK (0x3FFFFFFF)
 
+#define TPL_CAN_CLASSIC_FRAME_MAXIMUM_PAYLOAD_SIZE (8)
+#define TPL_CAN_FD_FRAME_MAXIMUM_PAYLOAD_SIZE (64)
+
 /**
  * @typedef tpl_can_protocol_version_t
  *

diff --git a/net/can/tpl_can_core.c b/net/can/tpl_can_core.c
@@ -99,6 +99,10 @@ Std_ReturnType Can_Write(Can_HwHandleType Hth, const Can_PduType *PduInfo)
 
 	if (controller == NULL)
 		return E_NOT_OK;
+	if (PduInfo == NULL)
+		return E_NOT_OK;
+
+	// TODO check if CAN FD enabled for CAN FD frame, otherwise send as CAN classic if SDU < 8 (see parag 7.12 "CAN FD Support" in AUTOSAR_SWS_CANDriver R22-11)
 
 	// No need to check for the transmit callback presence, this has already been done by Can_Init()
 	ret = controller->transmit(controller, PduInfo);
@@ -145,3 +149,32 @@ Std_ReturnType CanIf_ReadRxPduData(PduIdType CanIfRxSduId, PduInfoType *CanIfRxI
 	can_pdu = (Can_PduType *) CanIfRxInfoPtr->SduDataPtr;
 	return controller->receive(controller, can_pdu);
 }
+
+uint32 tpl_can_adjust_dlc(uint32 length, uint32 *adjusted_length)
+{
+	struct length_code_t
+	{
+		uint32 dlc;
+		uint32 adjusted_length;
+	};
+	static struct length_code_t length_code_table[TPL_CAN_FD_FRAME_MAXIMUM_PAYLOAD_SIZE + 1] =
+	{
+		{ 0x0,  0 }, { 0x1,  1 }, { 0x2,  2 }, { 0x3,  3 }, { 0x4,  4 }, { 0x5,  5 }, { 0x6,  6 }, { 0x7,  7 },
+		{ 0x8,  8 }, { 0x9, 12 }, { 0x9, 12 }, { 0x9, 12 }, { 0x9, 12 }, { 0xA, 16 }, { 0xA, 16 }, { 0xA, 16 },
+		{ 0xA, 16 }, { 0xB, 20 }, { 0xB, 20 }, { 0xB, 20 }, { 0xB, 20 }, { 0xC, 24 }, { 0xC, 24 }, { 0xC, 24 },
+		{ 0xC, 24 }, { 0xD, 32 }, { 0xD, 32 }, { 0xD, 32 }, { 0xD, 32 }, { 0xD, 32 }, { 0xD, 32 }, { 0xD, 32 },
+		{ 0xD, 32 }, { 0xE, 48 }, { 0xE, 48 }, { 0xE, 48 }, { 0xE, 48 }, { 0xE, 48 }, { 0xE, 48 }, { 0xE, 48 },
+		{ 0xE, 48 }, { 0xE, 48 }, { 0xE, 48 }, { 0xE, 48 }, { 0xE, 48 }, { 0xE, 48 }, { 0xE, 48 }, { 0xE, 48 },
+		{ 0xE, 48 }, { 0xF, 64 }, { 0xF, 64 }, { 0xF, 64 }, { 0xF, 64 }, { 0xF, 64 }, { 0xF, 64 }, { 0xF, 64 },
+		{ 0xF, 64 }, { 0xF, 64 }, { 0xF, 64 }, { 0xF, 64 }, { 0xF, 64 }, { 0xF, 64 }, { 0xF, 64 }, { 0xF, 64 },
+		{ 0xF, 64 }
+	};
+
+	if (length > TPL_CAN_FD_FRAME_MAXIMUM_PAYLOAD_SIZE)
+		return 0;
+
+	if (adjusted_length != NULL)
+		*adjusted_length = length_code_table[length].adjusted_length;
+
+	return length_code_table[length].dlc;
+}