can: c_can: Wait for CONTROL_INIT to be cleared

According to the documentation the CPU must wait for CONTROL_INIT to
be cleared before writing to the baudrate registers.

Signed-off-by: Benedikt Spranger <b.spranger@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 23 insertions, 3 deletions

diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
index 68839380086d..4d08a32f27ac 100644
--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -566,6 +566,21 @@ static netdev_tx_t c_can_start_xmit(struct sk_buff *skb,
         return NETDEV_TX_OK;
 }
 
+static int c_can_wait_for_ctrl_init(struct net_device *dev,
+                                    struct c_can_priv *priv, u32 init)
+{
+        int retry = 0;
+
+        while (init != (priv->read_reg(priv, C_CAN_CTRL_REG) & CONTROL_INIT)) {
+                udelay(10);
+                if (retry++ > 1000) {
+                        netdev_err(dev, "CCTRL: set CONTROL_INIT failed\n");
+                        return -EIO;
+                }
+        }
+        return 0;
+}
+
 static int c_can_set_bittiming(struct net_device *dev)
 {
         unsigned int reg_btr, reg_brpe, ctrl_save;
@@ -573,6 +588,7 @@ static int c_can_set_bittiming(struct net_device *dev)
         u32 ten_bit_brp;
         struct c_can_priv *priv = netdev_priv(dev);
         const struct can_bittiming *bt = &priv->can.bittiming;
+        int res;
 
         /* c_can provides a 6-bit brp and 4-bit brpe fields */
         ten_bit_brp = bt->brp - 1;
@@ -590,13 +606,17 @@ static int c_can_set_bittiming(struct net_device *dev)
                 "setting BTR=%04x BRPE=%04x\n", reg_btr, reg_brpe);
 
         ctrl_save = priv->read_reg(priv, C_CAN_CTRL_REG);
-        priv->write_reg(priv, C_CAN_CTRL_REG,
-                        ctrl_save | CONTROL_CCE | CONTROL_INIT);
+        ctrl_save &= ~CONTROL_INIT;
+        priv->write_reg(priv, C_CAN_CTRL_REG, CONTROL_CCE | CONTROL_INIT);
+        res = c_can_wait_for_ctrl_init(dev, priv, CONTROL_INIT);
+        if (res)
+                return res;
+
         priv->write_reg(priv, C_CAN_BTR_REG, reg_btr);
         priv->write_reg(priv, C_CAN_BRPEXT_REG, reg_brpe);
         priv->write_reg(priv, C_CAN_CTRL_REG, ctrl_save);
 
-        return 0;
+        return c_can_wait_for_ctrl_init(dev, priv, 0);
 }
 
 /*