nvmem: return -EOPNOTSUPP to in-kernel users on missing callbacks

__nvmem_reg_read/write() currently return -EINVAL if the relevant
callback is not present. User-space helpers again check the presence
of the callbacks to see if they should return -EPERM.

Ahead of adding SRCU synchronization: change the error code returned to
in-kernel users to -EOPNOTSUPP which is more indicative of the actual
reason for the failure.

Remove the checks from the sysfs attribute callbacks as these are not
visible without the required callbacks.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Tested-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
Signed-off-by: Srinivas Kandagatla <srini@kernel.org>
Link: https://patch.msgid.link/20260729094647.111468-3-srini@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

0 files changed, 0 insertions, 0 deletions