[PATCH v3 4/6] i2c: npcm: Modify the client address assignment

From: warp5tw
Date: Fri Sep 13 2024 - 06:16:39 EST


From: Tyrone Ting <kfting@xxxxxxxxxxx>

Store the client address earlier since it might get called in
the i2c_recover_bus logic flow at the early stage of the function
npcm_i2c_master_xfer.

Signed-off-by: Tyrone Ting <kfting@xxxxxxxxxxx>
Reviewed-by: Tali Perry <tali.perry1@xxxxxxxxx>
---
drivers/i2c/busses/i2c-npcm7xx.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-npcm7xx.c b/drivers/i2c/busses/i2c-npcm7xx.c
index 68f3d47323ab..e52e65e63600 100644
--- a/drivers/i2c/busses/i2c-npcm7xx.c
+++ b/drivers/i2c/busses/i2c-npcm7xx.c
@@ -2155,6 +2155,18 @@ static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,

} while (time_is_after_jiffies(time_left) && bus_busy);

+ /*
+ * Previously, the address was stored w/o left-shift by one bit and
+ * with that shift in the following call to npcm_i2c_master_start_xmit.
+ *
+ * Since there are cases that the i2c_recover_bus gets called at the
+ * early stage of the function npcm_i2c_master_xfer, the address is
+ * stored with the shift and used in the i2c_recover_bus call.
+ *
+ * The address is stored from bit 1 to bit 7 in the register for
+ * sending the i2c address later so it's left-shifted by 1 bit.
+ */
+ bus->dest_addr = slave_addr << 1;
if (bus_busy || bus->ber_state) {
iowrite8(NPCM_I2CCST_BB, bus->reg + NPCM_I2CCST);
npcm_i2c_reset(bus);
@@ -2163,7 +2175,6 @@ static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
}

npcm_i2c_init_params(bus);
- bus->dest_addr = slave_addr;
bus->msgs = msgs;
bus->msgs_num = num;
bus->cmd_err = 0;
--
2.34.1