On Wed, 23 Jun 2021 09:37:41 +0100
Jonathan Cameron [off-list ref] wrote:

On Tue, 22 Jun 2021 14:36:17 -0300
Marcelo Schmitt [off-list ref] wrote:

quoted

Hey Jonathan,

On 06/14, Jonathan Cameron wrote:  

quoted

From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Hi All,

This one proved an interesting diversion.

Work done against a somewhat hacked up QEMU emulation of 3 daisy chained
ad7280a devices (18 channels).  Note that the emulation isn't complete
but does do chaining, CRC, and readout of channels etc in a fashion that
worked with the original driver (up to the bug in patch 1) and continues
to work with the updated version. I've not intention to upstream the
emulation (as would need to make it more completed and flexible), but
happy to share it with anyone who is interested.    

I'm interested in seeing your device emulation with QEMU.
I was looking at the ad7150 emulation you shared earlier this year but had
some trouble getting the i2c slave created.  

Sure.  Let me do a bit of tidying up they I'll push a suitable branch out.
(probably will still have lots of stuff missing!)

Might take a little while to get to this though.

I pretended to myself for a few weeks that I'd get around to tidying this up in
a remotely meaningful way.  That's clearly not happening so I pushed out the
untidy version with appropriate eats babies messages:

https://github.com/jic23/qemu/commits/ad7280a-hacks

Note there is loads of stuff that isn't implemented as it was developed alongside
this patch series to verify individual patches rather than with the intent of
actually emulating the device.

It's hard coded to 2 a chain of 3 ad7280a devices because that seemed to hit most possible
corner cases.

The top commit has the launch string I'm using.  You'll need a filesystem, but
you can probably use one of the convenient ones debian posts as nocloud cloud
images. 

There is some info on that on people.kernel.org/jic23 as I wrote up how to test
CXL stuff on ARM recently and gave guidance on easy ways to get a filesystem.
http://cdimage.debian.org/cdimage/cloud/sid/daily/20210702-691/debian-sid-nocloud-arm64-daily-20210702-691.qcow2
will probably work and is more recent than the one linked from that blog post. 

Give me a shout if you need more specific guidance than this very very rough guide!

I mentioned this thread in the diversion the rust on linux thread took into
use of QEMU to emulate devices which motivated me to stop being lazy and at least
post this hideous version.  Probably the most useful bit is how to get a working
spi device emulated on the arm virt machine as that is very handy for all manner
of testing.  One day someone might implement a large set of IIO device emulation
and bolt it into a CI...

Jonathan

quoted

Being able to see it running, I may feel more confident to provide a review
for this set :)  

:)

quoted

Regards,

Marcelo  

quoted

I briefly flirted with posting a patch to just drop the driver entirely,
but the part is still available and it looked like fun + isn't going
to greatly impact maintainability of the subsystem long term so is low
cost even if it goes obsolete sometime soonish.

There are lots of things we could do after this set to improved the driver
and make things more flexible, but it should basically 'just work'

Anyhow, as normal for staging graduations, last patch has rename detection
turned off so that people can easily see what I am proposing we move
out of staging.

Jonathan Cameron (17):
  staging:iio:adc:ad7280a: Fix handing of device address bit reversing.
  staging:iio:adc:ad7280a: Register define cleanup.
  staging:iio:adc:ad7280a: rename _read() to _read_reg()
  staging:iio:adc:ad7280a: Split buff[2] into tx and rx parts
  staging:iio:adc:ad7280a: Use bitfield ops to managed fields in
    transfers.
  staging:iio:adc:ad7280a: Switch to standard event control
  staging:iio:adc:ad7280a: Standardize extended ABI naming
  staging:iio:adc:ad7280a: Drop unused timestamp channel.
  staging:iio:adc:ad7280a: Trivial comment formatting cleanup
  staging:iio:adc:ad7280a: Make oversampling_ratio a runtime control
  staging:iio:adc:ad7280a: Cleanup includes
  staging:iio:ad7280a: Reflect optionality of irq in ABI
  staging:iio:adc:ad7280a: Use a local dev pointer to avoid &spi->dev
  staging:iio:adc:ad7280a: Use device properties to replace platform
    data.
  dt-bindings:iio:adc:ad7280a: Add binding
  iio:adc:ad7280a: Document ABI for cell balance switches
  iio:adc:ad7280a: Move out of staging

 .../ABI/testing/sysfs-bus-iio-adc-ad7280a     |   14 +
 .../bindings/iio/adc/adi,ad7280a.yaml         |   87 ++
 drivers/iio/adc/Kconfig                       |   11 +
 drivers/iio/adc/Makefile                      |    1 +
 drivers/iio/adc/ad7280a.c                     | 1116 +++++++++++++++++
 drivers/staging/iio/adc/Kconfig               |   11 -
 drivers/staging/iio/adc/Makefile              |    1 -
 drivers/staging/iio/adc/ad7280a.c             | 1044 ---------------
 drivers/staging/iio/adc/ad7280a.h             |   37 -
 9 files changed, 1229 insertions(+), 1093 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-ad7280a
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad7280a.yaml
 create mode 100644 drivers/iio/adc/ad7280a.c
 delete mode 100644 drivers/staging/iio/adc/ad7280a.c
 delete mode 100644 drivers/staging/iio/adc/ad7280a.h

-- 
2.32.0