ad4851: add linux support

[amiclaus]

Description

Add ad485x family pyadi-iio support for the linux driver.

https://github.com/torvalds/linux/blob/master/drivers/iio/adc/ad4851.c

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How has this been tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Test A
• Test B

Test Configuration:

• Hardware: Zedboard + EVAL-AD4857
• OS: Linux

Documentation

If this is a new feature or example please mention or link any documentation. All new hardware interface classes require documentation.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have signed off all commits and they contain "Signed-off by: "
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[github-actions]

Generated documentation for this PR is available at Link

[github-actions]

Test Results

1 715 tests  +1     462 ✅ ±0   12m 1s ⏱️ -3s
    1 suites ±0   1 253 💤 +1 
    1 files   ±0       0 ❌ ±0 

Results for commit 6c7049d. ± Comparison against base commit b89168a.

This pull request removes 4 and adds 5 tests. Note that renamed tests count towards both.

test.test_adrv9002_p ‑ test_adrv9002_hardware_gain[attr=rx_hardwaregain_chan0-val=[0.5, 11.0, 33.0, 31.0, 30.0, 14.0, 11.0, 4.0, 10.5, 1.0]-depends={'gain_control_mode_chan0': 'spi', 'rx_ensm_mode_chan0': 'rf_enabled'}-classname=adi.adrv9002]
test.test_adrv9002_p ‑ test_adrv9002_hardware_gain[attr=rx_hardwaregain_chan0-val=[8.0, 7.0, 12.0, 5.0, 19.5, 21.5, 25.0, 19.5, 24.5, 24.5]-depends={'gain_control_mode_chan1': 'spi', 'rx_ensm_mode_chan1': 'rf_enabled'}-classname=adi.adrv9002]
test.test_adrv9002_p ‑ test_adrv9002_hardware_gain[attr=tx_hardwaregain_chan0-val=[-32.7, -23.7, -3.0, -31.25, -6.9, -28.45, -1.05, -18.0, -19.4, -1.45]-depends={'atten_control_mode_chan0': 'spi'}-classname=adi.adrv9002]
test.test_adrv9002_p ‑ test_adrv9002_hardware_gain[attr=tx_hardwaregain_chan1-val=[-5.55, -17.9, -11.85, -33.15, -25.7, -37.1, -16.25, -2.5, -29.4, -22.25]-depends={'atten_control_mode_chan1': 'spi'}-classname=adi.adrv9002]

test.test_ad4851 ‑ test_ad4851_rx_data[channel=0-classname=adi.ad4851]
test.test_adrv9002_p ‑ test_adrv9002_hardware_gain[attr=rx_hardwaregain_chan0-val=[31.0, 32.0, 22.5, 9.0, 31.0, 9.0, 28.0, 25.5, 29.5, 20.0]-depends={'gain_control_mode_chan1': 'spi', 'rx_ensm_mode_chan1': 'rf_enabled'}-classname=adi.adrv9002]
test.test_adrv9002_p ‑ test_adrv9002_hardware_gain[attr=rx_hardwaregain_chan0-val=[31.5, 24.0, 13.5, 34.0, 16.0, 31.5, 15.0, 11.5, 11.0, 28.0]-depends={'gain_control_mode_chan0': 'spi', 'rx_ensm_mode_chan0': 'rf_enabled'}-classname=adi.adrv9002]
test.test_adrv9002_p ‑ test_adrv9002_hardware_gain[attr=tx_hardwaregain_chan0-val=[-31.6, -3.05, -27.3, -36.45, -4.65, -33.45, -39.75, -7.0, -1.1, -13.65]-depends={'atten_control_mode_chan0': 'spi'}-classname=adi.adrv9002]
test.test_adrv9002_p ‑ test_adrv9002_hardware_gain[attr=tx_hardwaregain_chan1-val=[-13.35, -25.1, -17.9, -26.2, -18.4, -30.55, -34.25, -9.3, -34.5, -30.75]-depends={'atten_control_mode_chan1': 'spi'}-classname=adi.adrv9002]

♻️ This comment has been updated with latest results.

[tfcollins]

This needs to include all parts now supported by the AD4851 class

[tfcollins]

Just minor issues

[tfcollins]

Will need a rebase

[amiclaus]

v2:

• add all supported parts
• fix conflicts