[PATCH RFC 0/3] iio: add helpers and accessors for active channels and masklength

[Nuno Sa <nuno.sa@analog.com>]

Hi Jonathan,

In [1], you suggested for an iterator for the active channels (so driver
don't directly access masklength). This RFC showcases that iterator and
goes one step further by giving an accessors for masklength so that
drivers can read that variable (we have drivers doing that). The
accessors uses ACCESS_PRIVATE() so it will warn us if some driver
directly access the variable making it more difficult to mess with it
(like changing it's value) without being noticed during review (or the
auto builders).

Anyways, before jumping in changing all the drivers using this, I guess
the questions are:

1) Is the iterator useful enough to add one (kind of like it and save a
line of code :))?
2) Do we care about going with the work of marking masklength private? 

If we go ahead the plan would be:

1) Add the helpers macros;
2) Convert all drivers that directly access 'masklength';
3) Annotate it as private.

[1]: https://lore.kernel.org/linux-iio/20240428142343.5067c898@jic23-huawei/

---
Nuno Sa (3):
      iio: core: add new helper to iterate active channels
      iio: imu: adis16475: make use of iio_for_each_active_channel()
      iio: core annotate masklength as private

 drivers/iio/imu/adis16475.c | 3 +--
 include/linux/iio/iio.h     | 8 +++++++-
 2 files changed, 8 insertions(+), 3 deletions(-)
---
base-commit: cc1ce839526a65620778617da0b022bd88e8a139
change-id: 20240612-dev-iio-scan-private-86f4a0fd288f
--

Thanks!
- Nuno Sá