netdev - [PATCH net-next 14/48] can: rcar_can: CTLR bitfield conversion

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Message-ID: <20250925121332.848157-15-mkl@pengutronix.de>
Date: Thu, 25 Sep 2025 14:07:51 +0200
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
	kuba@...nel.org,
	linux-can@...r.kernel.org,
	kernel@...gutronix.de,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH net-next 14/48] can: rcar_can: CTLR bitfield conversion

From: Geert Uytterhoeven <geert+renesas@...der.be>

Convert CAN Control Register field accesses to use the FIELD_PREP()
bitfield access macro.  Add a few more comments and definitions while at
it.

This gets rid of explicit (and sometimes confusing) shifts.

Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
Link: https://patch.msgid.link/077640e31949dc3c9d128a08ade94c9e9cd25672.1755857536.git.geert+renesas@glider.be
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/rcar/rcar_can.c | 33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/drivers/net/can/rcar/rcar_can.c b/drivers/net/can/rcar/rcar_can.c
index 7b94224bbc9b..8b4356fcd7d2 100644
--- a/drivers/net/can/rcar/rcar_can.c
+++ b/drivers/net/can/rcar/rcar_can.c
@@ -5,6 +5,7 @@
  * Copyright (C) 2013 Renesas Solutions Corp.
  */
 
+#include <linux/bitfield.h>
 #include <linux/bits.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
@@ -115,16 +116,19 @@ static const struct can_bittiming_const rcar_can_bittiming_const = {
 
 /* Control Register bits */
 #define RCAR_CAN_CTLR_BOM	GENMASK(12, 11)	/* Bus-Off Recovery Mode Bits */
-#define RCAR_CAN_CTLR_BOM_ENT	(1 << 11) /* Entry to halt mode */
-					/* at bus-off entry */
+#define RCAR_CAN_CTLR_BOM_ENT		1	/* Entry to halt mode */
+						/* at bus-off entry */
 #define RCAR_CAN_CTLR_SLPM	BIT(10)		/* Sleep Mode */
 #define RCAR_CAN_CTLR_CANM	GENMASK(9, 8)	/* Operating Mode Select Bit */
-#define RCAR_CAN_CTLR_CANM_HALT	(1 << 9)
-#define RCAR_CAN_CTLR_CANM_RESET (1 << 8)
-#define RCAR_CAN_CTLR_CANM_FORCE_RESET (3 << 8)
+#define RCAR_CAN_CTLR_CANM_OPER		0	/* Operation Mode */
+#define RCAR_CAN_CTLR_CANM_RESET	1	/* Reset Mode */
+#define RCAR_CAN_CTLR_CANM_HALT		2	/* Halt Mode */
+#define RCAR_CAN_CTLR_CANM_FORCE_RESET	3	/* Reset Mode (forcible) */
 #define RCAR_CAN_CTLR_MLM	BIT(3)		/* Message Lost Mode Select */
 #define RCAR_CAN_CTLR_IDFM	GENMASK(2, 1)	/* ID Format Mode Select Bits */
-#define RCAR_CAN_CTLR_IDFM_MIXED (1 << 2) /* Mixed ID mode */
+#define RCAR_CAN_CTLR_IDFM_STD		0	/* Standard ID mode */
+#define RCAR_CAN_CTLR_IDFM_EXT		1	/* Extended ID mode */
+#define RCAR_CAN_CTLR_IDFM_MIXED	2	/* Mixed ID mode */
 #define RCAR_CAN_CTLR_MBM	BIT(0)		/* Mailbox Mode select */
 
 /* Status Register bits */
@@ -453,16 +457,17 @@ static void rcar_can_start(struct net_device *ndev)
 	ctlr &= ~RCAR_CAN_CTLR_SLPM;
 	writew(ctlr, &priv->regs->ctlr);
 	/* Go to reset mode */
-	ctlr |= RCAR_CAN_CTLR_CANM_FORCE_RESET;
+	ctlr |= FIELD_PREP(RCAR_CAN_CTLR_CANM, RCAR_CAN_CTLR_CANM_FORCE_RESET);
 	writew(ctlr, &priv->regs->ctlr);
 	for (i = 0; i < MAX_STR_READS; i++) {
 		if (readw(&priv->regs->str) & RCAR_CAN_STR_RSTST)
 			break;
 	}
 	rcar_can_set_bittiming(ndev);
-	ctlr |= RCAR_CAN_CTLR_IDFM_MIXED; /* Select mixed ID mode */
-	ctlr |= RCAR_CAN_CTLR_BOM_ENT;	/* Entry to halt mode automatically */
-					/* at bus-off */
+	/* Select mixed ID mode */
+	ctlr |= FIELD_PREP(RCAR_CAN_CTLR_IDFM, RCAR_CAN_CTLR_IDFM_MIXED);
+	/* Entry to halt mode automatically at bus-off */
+	ctlr |= FIELD_PREP(RCAR_CAN_CTLR_BOM, RCAR_CAN_CTLR_BOM_ENT);
 	ctlr |= RCAR_CAN_CTLR_MBM;	/* Select FIFO mailbox mode */
 	ctlr |= RCAR_CAN_CTLR_MLM;	/* Overrun mode */
 	writew(ctlr, &priv->regs->ctlr);
@@ -492,7 +497,9 @@ static void rcar_can_start(struct net_device *ndev)
 	priv->can.state = CAN_STATE_ERROR_ACTIVE;
 
 	/* Go to operation mode */
-	writew(ctlr & ~RCAR_CAN_CTLR_CANM, &priv->regs->ctlr);
+	ctlr &= ~RCAR_CAN_CTLR_CANM;
+	ctlr |= FIELD_PREP(RCAR_CAN_CTLR_CANM, RCAR_CAN_CTLR_CANM_OPER);
+	writew(ctlr, &priv->regs->ctlr);
 	for (i = 0; i < MAX_STR_READS; i++) {
 		if (!(readw(&priv->regs->str) & RCAR_CAN_STR_RSTST))
 			break;
@@ -553,7 +560,7 @@ static void rcar_can_stop(struct net_device *ndev)
 
 	/* Go to (force) reset mode */
 	ctlr = readw(&priv->regs->ctlr);
-	ctlr |= RCAR_CAN_CTLR_CANM_FORCE_RESET;
+	ctlr |= FIELD_PREP(RCAR_CAN_CTLR_CANM, RCAR_CAN_CTLR_CANM_FORCE_RESET);
 	writew(ctlr, &priv->regs->ctlr);
 	for (i = 0; i < MAX_STR_READS; i++) {
 		if (readw(&priv->regs->str) & RCAR_CAN_STR_RSTST)
@@ -847,7 +854,7 @@ static int rcar_can_suspend(struct device *dev)
 	netif_device_detach(ndev);
 
 	ctlr = readw(&priv->regs->ctlr);
-	ctlr |= RCAR_CAN_CTLR_CANM_HALT;
+	ctlr |= FIELD_PREP(RCAR_CAN_CTLR_CANM, RCAR_CAN_CTLR_CANM_HALT);
 	writew(ctlr, &priv->regs->ctlr);
 	ctlr |= RCAR_CAN_CTLR_SLPM;
 	writew(ctlr, &priv->regs->ctlr);
-- 
2.51.0