To facilitate backends with different set of features, add support
for defining capabilities provided by the backend. These capabilities
typically extend beyond a single operation and are therefore not
directly linked to if a single function call is implemented or not.
Furthermore, the capabilities determine if a certain set of operations
should be attempted, or skipped by the frontend. This way
the frontend driver can work with a minimalistic set of features and
still have the device in fully functional state.
Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
---
Changes in v5:
- As per recommendation, use guard for whole block
- Typo fix in commit message and cover letter
- Link to v4: https://lore.kernel.org/r/20260121-b4-ad9467-optional-backend-v4-0-18d2c0d450cc@vaisala.com
Changes in v4:
- Readd CAP_BUFFERING and also add CAP_ALWAYS_ON to support backends
that do not need explicit enable/disable
- Don't mix checks for eopnotsupp and caps. Prefer capability checking
also for caps that map to single operation
- Move capability checking to top of call stack
- Revise iio_backend_has_caps to use bool signature and fixup semantics
- Amend documentation texts
- Add capability checks for axi-dac
- Drop two's complement patch from this series, already applied
- Link to v3: https://lore.kernel.org/r/20260114-b4-ad9467-optional-backend-v3-0-d2c84979d010@vaisala.com
Changes in v3:
- Reduce set of capabilities to only include calibration. The other
ones propsed in V2 can be seen as subset of calibration, or single
operation failing with opnotsupported
- Rename backends checking function
- Relocate caps field inside backend struct (pahole)
- Add kernel-docs
- Add capabilites for exisiting backend variants
- Link to v2: https://lore.kernel.org/r/20260113-b4-ad9467-optional-backend-v2-0-0a27e7e72f41@vaisala.com
Changes in v2:
- Added industrialio-backend capabilities feature
- Removed acceptance for fully optional backend, instead require atleast
minimalistic backend to exist
- Switched to FIELD_MODIFY()
- Fixed kernel test robot reported failure for missing bitfield.h
- Link to v1: https://lore.kernel.org/r/20251216-b4-ad9467-optional-backend-v1-0-83e61531ef4d@vaisala.com
---
Tomas Melin (4):
iio: industrialio-backend: support backend capabilities
iio: adc: adi-axi-adc: define supported iio-backend capabilities
iio: dac: adi-axi-dac: define supported iio-backend capabilities
iio: adc: ad9467: check for backend capabilities
drivers/iio/adc/ad9467.c | 69 ++++++++++++++++++++++++--------------
drivers/iio/adc/adi-axi-adc.c | 3 ++
drivers/iio/dac/adi-axi-dac.c | 2 ++
drivers/iio/industrialio-backend.c | 16 +++++++++
include/linux/iio/backend.h | 25 ++++++++++++++
5 files changed, 89 insertions(+), 26 deletions(-)
---
base-commit: a7b10f0963c651a6406d958a5f64b9c5594f84da
change-id: 20251215-b4-ad9467-optional-backend-23f1099ee4d7
Best regards,
--
Tomas Melin <tomas.melin@vaisala.com>