i2c: rcar: ensure Gen3+ reset does not disturb local targets

R-Car Gen3+ needs a reset before every controller transfer. That erases
configuration of a potentially in parallel running local target
instance. To avoid this disruption, avoid controller transfers if a
local target is running. Also, disable SMBusHostNotify because it
requires being a controller and local target at the same time.

Fixes: 3b770017 ("i2c: rcar: handle RXDMA HW behaviour on Gen3")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>

drivers/i2c/busses/i2c-rcar.c

@@ -883,6 +883,10 @@ static int rcar_i2c_do_reset(struct rcar_i2c_priv *priv)
 {
 	int ret;
 
+	/* Don't reset if a slave instance is currently running */
+	if (priv->slave)
+		return -EISCONN;
+
 	ret = reset_control_reset(priv->rstc);
 	if (ret)
 		return ret;
@@ -1175,6 +1179,7 @@ static int rcar_i2c_probe(struct platform_device *pdev)
 	if (of_property_read_bool(dev->of_node, "smbus"))
 		priv->flags |= ID_P_HOST_NOTIFY;
 
+	/* R-Car Gen3+ needs a reset before every transfer */
 	if (priv->devtype >= I2C_RCAR_GEN3) {
 		priv->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
 		if (IS_ERR(priv->rstc)) {
@@ -1185,6 +1190,9 @@ static int rcar_i2c_probe(struct platform_device *pdev)
 		ret = reset_control_status(priv->rstc);
 		if (ret < 0)
 			goto out_pm_put;
+
+		/* hard reset disturbs HostNotify local target, so disable it */
+		priv->flags &= ~ID_P_HOST_NOTIFY;
 	}
 
 	ret = platform_get_irq(pdev, 0);