netdev - [PATCH v4 3/6] can: sja1000: Add Quirk for RZ/N1 SJA1000 CAN controller

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Message-Id: <20220710115248.190280-4-biju.das.jz@bp.renesas.com>
Date:   Sun, 10 Jul 2022 12:52:45 +0100
From:   Biju Das <biju.das.jz@...renesas.com>
To:     Wolfgang Grandegger <wg@...ndegger.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     Biju Das <biju.das.jz@...renesas.com>,
        Stefan Mätje <stefan.maetje@....eu>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Chris Paterson <Chris.Paterson2@...esas.com>,
        Biju Das <biju.das@...renesas.com>,
        linux-renesas-soc@...r.kernel.org
Subject: [PATCH v4 3/6] can: sja1000: Add Quirk for RZ/N1 SJA1000 CAN controller

As per Chapter 6.5.16 of the RZ/N1 Peripheral Manual, The SJA1000
CAN controller does not support Clock Divider Register compared to
the reference Philips SJA1000 device.

This patch adds a device quirk to handle this difference.

Signed-off-by: Biju Das <biju.das.jz@...renesas.com>
---
v3->v4:
 * Optimized the code as per Vincent's suggestion.
v2->v3:
 * No Change
v1->v2:
 * Updated commit description
 * Removed the quirk macro SJA1000_NO_HW_LOOPBACK_QUIRK
 * Added prefix SJA1000_QUIRK_* for quirk macro.
---
 drivers/net/can/sja1000/sja1000.c | 8 +++++---
 drivers/net/can/sja1000/sja1000.h | 3 ++-
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/sja1000/sja1000.c b/drivers/net/can/sja1000/sja1000.c
index 2e7638f98cf1..d9da471f1bb9 100644
--- a/drivers/net/can/sja1000/sja1000.c
+++ b/drivers/net/can/sja1000/sja1000.c
@@ -183,8 +183,9 @@ static void chipset_init(struct net_device *dev)
 {
 	struct sja1000_priv *priv = netdev_priv(dev);
 
-	/* set clock divider and output control register */
-	priv->write_reg(priv, SJA1000_CDR, priv->cdr | CDR_PELICAN);
+	if (!(priv->flags & SJA1000_QUIRK_NO_CDR_REG))
+		/* set clock divider and output control register */
+		priv->write_reg(priv, SJA1000_CDR, priv->cdr | CDR_PELICAN);
 
 	/* set acceptance filter (accept all) */
 	priv->write_reg(priv, SJA1000_ACCC0, 0x00);
@@ -209,7 +210,8 @@ static void sja1000_start(struct net_device *dev)
 		set_reset_mode(dev);
 
 	/* Initialize chip if uninitialized at this stage */
-	if (!(priv->read_reg(priv, SJA1000_CDR) & CDR_PELICAN))
+	if (!(priv->flags & SJA1000_QUIRK_NO_CDR_REG ||
+	      priv->read_reg(priv, SJA1000_CDR) & CDR_PELICAN))
 		chipset_init(dev);
 
 	/* Clear error counters and error code capture */
diff --git a/drivers/net/can/sja1000/sja1000.h b/drivers/net/can/sja1000/sja1000.h
index 9d46398f8154..7f736f1df547 100644
--- a/drivers/net/can/sja1000/sja1000.h
+++ b/drivers/net/can/sja1000/sja1000.h
@@ -145,7 +145,8 @@
 /*
  * Flags for sja1000priv.flags
  */
-#define SJA1000_CUSTOM_IRQ_HANDLER 0x1
+#define SJA1000_CUSTOM_IRQ_HANDLER	BIT(0)
+#define SJA1000_QUIRK_NO_CDR_REG	BIT(1)
 
 /*
  * SJA1000 private data structure
-- 
2.25.1