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.

Link: https://lore.kernel.org/all/20220710115248.190280-4-biju.das.jz@bp.renesas.com
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/sja1000/sja1000.c b/drivers/net/can/sja1000/sja1000.c
index 2e7638f..d9da471 100644 (file)
--- 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 9d46398..7f736f1 100644 (file)
--- 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