i2c: imx-lpi2c: avoid accessing target registers on master-only controllers

Not all LPI2C controller instances implement the Target block.
Since commit 90311787f483 ("i2c: imx-lpi2c: reset controller in
probe stage"), the driver unconditionally resets both the Master
and Target blocks during probe.

On controllers that do not support target mode, accessing the
Target registers triggers an asynchronous SError and prevents the
driver from probing successfully. For example on i.MX8QM:

  SError Interrupt on CPU2, code 0x00000000bf000002 -- SError
  Hardware name: Freescale i.MX8QM MEK (DT)
  pc : lpi2c_imx_probe+0x280/0x594
  lr : lpi2c_imx_probe+0x224/0x594
  Kernel panic - not syncing: Asynchronous SError Interrupt

The VERID register is implemented in the Master block and can be
safely accessed on all controller variants. Its FEATURE field
indicates whether target mode is supported.

Read VERID during probe and use it to determine whether the
Target block is present. Only access Target registers when target
mode is supported and reject target registration requests with
-EOPNOTSUPP otherwise.

Fixes: 90311787f483 ("i2c: imx-lpi2c: reset controller in probe stage")
Signed-off-by: Carlos Song <carlos.song@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://patch.msgid.link/20260803032705.2250373-1-carlos.song@oss.nxp.com

0 files changed, 0 insertions, 0 deletions