i2c: rcar: bring hardware to known state when probing

When probing, the hardware is not brought into a known state. This may
be a problem when a hypervisor restarts Linux without resetting the
hardware, leaving an old state running. Make sure the hardware gets
initialized, especially interrupts should be cleared and disabled.

Reported-by: Dirk Behme <dirk.behme@de.bosch.com>
Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Closes: https://lore.kernel.org/r/20240702045535.2000393-1-dirk.behme@de.bosch.com
Fixes: 6ccbe607132b ("i2c: add Renesas R-Car I2C driver")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 828aa2e..ec73463 100644 (file)
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -257,6 +257,14 @@ static void rcar_i2c_init(struct rcar_i2c_priv *priv)
        }
 }
 
+static void rcar_i2c_reset_slave(struct rcar_i2c_priv *priv)
+{
+       rcar_i2c_write(priv, ICSIER, 0);
+       rcar_i2c_write(priv, ICSSR, 0);
+       rcar_i2c_write(priv, ICSCR, SDBS);
+       rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */
+}
+
 static int rcar_i2c_bus_barrier(struct rcar_i2c_priv *priv)
 {
        int ret;
@@ -1033,11 +1041,8 @@ static int rcar_unreg_slave(struct i2c_client *slave)
 
        /* ensure no irq is running before clearing ptr */
        disable_irq(priv->irq);
-       rcar_i2c_write(priv, ICSIER, 0);
-       rcar_i2c_write(priv, ICSSR, 0);
+       rcar_i2c_reset_slave(priv);
        enable_irq(priv->irq);
-       rcar_i2c_write(priv, ICSCR, SDBS);
-       rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */
 
        priv->slave = NULL;
 
@@ -1152,7 +1157,9 @@ static int rcar_i2c_probe(struct platform_device *pdev)
                goto out_pm_disable;
        }
 
-       rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */
+       /* Bring hardware to known state */
+       rcar_i2c_init(priv);
+       rcar_i2c_reset_slave(priv);
 
        if (priv->devtype < I2C_RCAR_GEN3) {
                irqflags |= IRQF_NO_THREAD;