[PATCH v2 1/3] i2c: rcar: bring hardware to known state when probing

Wolfram Sang
2024-07-07T08:28:59Z

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>
---

Should go to for-current.

Changes since v1:
* renamed new function to *_reset_slave() instead of *_init_slave()
which is more appropriate
* do not mention refactorization in commit message
* added Fixes tag

drivers/i2c/busses/i2c-rcar.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 828aa2ea0fe4..ec73463ea9b5 100644
--- 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;
--
2.43.0