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Sharing a driver between similar devices

Michael Hope
 

Hi there.  I'm porting Zephyr to the Arduino Nano 33 IOT.  The board has a LSM6DS3 IMU which is very similar to the LSM6DSL that's already supported by Zephyr and I'd like to re-use it.

I've refactored [1] the lsm6dsl driver to be multi-instance.  What's the best way of then using the same driver for two different compats?  The best I've come up with is [2] but that has name collision issues.

Note that the chips also have a different WHO_AM_I value, so need very slightly different configuration.


-- Michael
Bolivar, Marti
 

Hi Michael,

"Michael Hope via lists.zephyrproject.org"
<michaelh=juju.nz@lists.zephyrproject.org> writes:

Hi there. I'm porting Zephyr to the Arduino Nano 33 IOT. The board has a
LSM6DS3 IMU which is very similar to the LSM6DSL that's already supported
by Zephyr and I'd like to re-use it.

I've refactored [1] the lsm6dsl driver to be multi-instance. What's the
best way of then using the same driver for two different compats? The best
I've come up with is [2] but that has name collision issues.
Have you tried to set some state in the config structure based on the
value of DT_NODE_HAS_COMPAT(DT_DRV_INST(your_instance_number), some_compat)?


Note that the chips also have a different WHO_AM_I value, so need very
slightly different configuration.
E.g. setting the WHO_AM_I in your config struct based on this, and using
that in your init functions to disambiguate.


[1]: https://github.com/zephyrproject-rtos/zephyr/pull/27064
[2]:
https://github.com/zephyrproject-rtos/zephyr/commit/cd65c39b3eeaa0d21ba90c30b13e4ca2952a6723

-- Michael
Thanks,
Martí
Michael Hope
 

On Fri, 24 Jul 2020 at 22:06, Bolivar, Marti <Marti.Bolivar@...> wrote:
Hi Michael,

"Michael Hope via lists.zephyrproject.org"
<michaelh=juju.nz@...> writes:

> Hi there.  I'm porting Zephyr to the Arduino Nano 33 IOT.  The board has a
> LSM6DS3 IMU which is very similar to the LSM6DSL that's already supported
> by Zephyr and I'd like to re-use it.
>
> I've refactored [1] the lsm6dsl driver to be multi-instance.  What's the
> best way of then using the same driver for two different compats?  The best
> I've come up with is [2] but that has name collision issues.

Have you tried to set some state in the config structure based on the
value of DT_NODE_HAS_COMPAT(DT_DRV_INST(your_instance_number), some_compat)?

That sounds good.

The second part of the problem is iterating over both the lsm6dsl and lsm6ds3 types.  Doing two DT_INST_FOREACH_STATUS_OKAY(fn), one for each compat, can give name collisions.  Any ideas?

-- Michael


>
> Note that the chips also have a different WHO_AM_I value, so need very
> slightly different configuration.

E.g. setting the WHO_AM_I in your config struct based on this, and using
that in your init functions to disambiguate.

>
> [1]: https://github.com/zephyrproject-rtos/zephyr/pull/27064
> [2]:
> https://github.com/zephyrproject-rtos/zephyr/commit/cd65c39b3eeaa0d21ba90c30b13e4ca2952a6723
>
> -- Michael

Thanks,
Martí

>
>

Peter A. Bigot
 

I believe https://github.com/zephyrproject-rtos/zephyr/issues/20287 is relevant to this problem.   At the time there was no solution; now it may be that 
DT_NODE_HAS_COMPAT(DT_DRV_INST(N), other_compat) handles it if just you iterate over the base lsm6dsl device.
William Fish
 

Michael,
Some interesting thoughts but it might be worth having a look at the lsm9ds0_mfd driver, it has configuration options for the various sensor functions. This might be a good guide to help achieve what you're planning.

Billy..
Bolivar, Marti
 

Michael Hope <michaelh@juju.nz> writes:

On Fri, 24 Jul 2020 at 22:06, Bolivar, Marti <Marti.Bolivar@nordicsemi.no>
wrote:

Hi Michael,

"Michael Hope via lists.zephyrproject.org"
<michaelh=juju.nz@lists.zephyrproject.org> writes:

Hi there. I'm porting Zephyr to the Arduino Nano 33 IOT. The board has
a
LSM6DS3 IMU which is very similar to the LSM6DSL that's already supported
by Zephyr and I'd like to re-use it.

I've refactored [1] the lsm6dsl driver to be multi-instance. What's the
best way of then using the same driver for two different compats? The
best
I've come up with is [2] but that has name collision issues.
Have you tried to set some state in the config structure based on the
value of DT_NODE_HAS_COMPAT(DT_DRV_INST(your_instance_number),
some_compat)?
That sounds good.

The second part of the problem is iterating over both the lsm6dsl and
lsm6ds3 types. Doing two DT_INST_FOREACH_STATUS_OKAY(fn), one for each
compat, can give name collisions. Any ideas?
Could you please describe the collisions in more detail? I checked the
patch in your footnote [2] below but I'm not seeing the issue, sorry.

Taking a guess, though, if there's an issue with naming a global
variable for a device config or data field within the "fn" expansion,
perhaps pasting DT_DRV_COMPAT onto the relevant variable names using the
## preprocessor operator is a fix?

Thanks,
Martí


-- Michael



Note that the chips also have a different WHO_AM_I value, so need very
slightly different configuration.
E.g. setting the WHO_AM_I in your config struct based on this, and using
that in your init functions to disambiguate.


[1]: https://github.com/zephyrproject-rtos/zephyr/pull/27064
[2]:
https://github.com/zephyrproject-rtos/zephyr/commit/cd65c39b3eeaa0d21ba90c30b13e4ca2952a6723

-- Michael
Thanks,
Martí
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