can: m_can: make TXESC, RXESC config more explicit

Introduce masks for the three RXESC fields (RBDS, F1DS, F0DS) and the
one TXESC field (TBDS). Update m_can_chip_config() to explicitly set all
four fields to the 64-byte option (0x7) (and these defs are renamed to
be more concise).

This is an improvement in maintainability, and also makes it easier to
implement more flexible configuration of the M_CAN buffers in the
future.

Link: https://lore.kernel.org/r/20210504125123.500553-4-torin@maxiluxsystems.comSigned-off-by: Torin Cooper-Bennun <torin@maxiluxsystems.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/m_can/m_can.c

@@ -235,8 +235,10 @@ enum m_can_reg {
 #define RXFS_FFL_MASK	GENMASK(6, 0)
 
 /* Rx Buffer / FIFO Element Size Configuration (RXESC) */
-#define M_CAN_RXESC_8BYTES	0x0
-#define M_CAN_RXESC_64BYTES	0x777
+#define RXESC_RBDS_MASK		GENMASK(10, 8)
+#define RXESC_F1DS_MASK		GENMASK(6, 4)
+#define RXESC_F0DS_MASK		GENMASK(2, 0)
+#define RXESC_64B		0x7
 
 /* Tx Buffer Configuration (TXBC) */
 #define TXBC_TFQS_MASK		GENMASK(29, 24)
@@ -249,8 +251,8 @@ enum m_can_reg {
 #define TXFQS_TFFL_MASK		GENMASK(5, 0)
 
 /* Tx Buffer Element Size Configuration(TXESC) */
-#define TXESC_TBDS_8BYTES	0x0
-#define TXESC_TBDS_64BYTES	0x7
+#define TXESC_TBDS_MASK		GENMASK(2, 0)
+#define TXESC_TBDS_64B		0x7
 
 /* Tx Event FIFO Configuration (TXEFC) */
 #define TXEFC_EFS_MASK		GENMASK(21, 16)
@@ -1191,7 +1193,10 @@ static void m_can_chip_config(struct net_device *dev)
 	m_can_config_endisable(cdev, true);
 
 	/* RX Buffer/FIFO Element Size 64 bytes data field */
-	m_can_write(cdev, M_CAN_RXESC, M_CAN_RXESC_64BYTES);
+	m_can_write(cdev, M_CAN_RXESC,
+		    FIELD_PREP(RXESC_RBDS_MASK, RXESC_64B) |
+		    FIELD_PREP(RXESC_F1DS_MASK, RXESC_64B) |
+		    FIELD_PREP(RXESC_F0DS_MASK, RXESC_64B));
 
 	/* Accept Non-matching Frames Into FIFO 0 */
 	m_can_write(cdev, M_CAN_GFC, 0x0);
@@ -1209,7 +1214,8 @@ static void m_can_chip_config(struct net_device *dev)
 	}
 
 	/* support 64 bytes payload */
-	m_can_write(cdev, M_CAN_TXESC, TXESC_TBDS_64BYTES);
+	m_can_write(cdev, M_CAN_TXESC,
+		    FIELD_PREP(TXESC_TBDS_MASK, TXESC_TBDS_64B));
 
 	/* TX Event FIFO */
 	if (cdev->version == 30) {