Add support for TI ADS7828/ADS7830 I2C ADCs

[TheMightyMadman]

This patch adds the TI ADS7828/ADS7830 I2C ADCs to the i2c-sensors overlay, and adds the appropriate hwmon driver as a module include in the default kernel configurations. I needed this for a project & it would be useful to have in-tree.

It also adds support for the hwmon driver "label" property - I haven't added this to the other drivers at this stage, as it is outside of the scope of this pull request, and it may only be supported by the hwmon drivers and not IIO drivers.

Tested and working OK on a CM4 with a pair of ADS7830 ADCs, overrides in /boot/firmware/config.txt as follows:
dtoverlay=i2c-sensor,ads7830,i2c_csi_dsi,addr=0x48,label="adc-1"
dtoverlay=i2c-sensor,ads7830,i2c_csi_dsi,addr=0x49,label="adc-2"

[6by9]

Forum thread https://forums.raspberrypi.com/viewtopic.php?p=2312304

[6by9]

Looks largely fine to me.

Two things:

• Patches 1 & 3 want to be squashed together
• we've gained arm64 / bcm2711_rt_defconfig as an extra defconfig recently for the realtime kernel. Could you add the module to that too please?

[TheMightyMadman]

Looks largely fine to me.

Two things:

• Patches 1 & 3 want to be squashed together
• we've gained arm64 / bcm2711_rt_defconfig as an extra defconfig recently for the realtime kernel. Could you add the module to that too please?

Thank you :) Apologies for the third commit, that was fixing a mistake I made in the first commit as I couldn't revert back to it (my git command line skills are limited at best).

And I'd be happy to add the extra config file, sure - thanks.

Do you just need all of the config changes in a single commit? I could add a commit reverting my config changes, then add a fresh commit with everything fixed and including the additional config file.

[pelwell]

To merge the 1st and 3rd commits:

$ git rebase -i HEAD~3
# Move the 3rd line up into 2nd place, and change the 'pick' to 'fixup' (or just 'f'), then close the editor
# You should now have 2 commits
$ git push --force TheMightyMadman HEAD:add_ads7828
# You may have a different name for the remote which is your fork of our Linux repo

[pelwell]

Note that there is a strict 80 character limit on lines in the README.

[TheMightyMadman]

To merge the 1st and 3rd commits:

$ git rebase -i HEAD~3
# Move the 3rd line up into 2nd place, and change the 'pick' to 'fixup' (or just 'f'), then close the editor
# You should now have 2 commits
$ git push --force TheMightyMadman HEAD:add_ads7828
# You may have a different name for the remote which is your fork of our Linux repo

This was very useful, thank you!
I've used this to fix the original configuration commit, and also add an entry to bcm2711_rt_defconfig.
Noted regarding the 80-character README line limit, I'll make the appropriate changes.

[TheMightyMadman]

To merge the 1st and 3rd commits:

$ git rebase -i HEAD~3
# Move the 3rd line up into 2nd place, and change the 'pick' to 'fixup' (or just 'f'), then close the editor
# You should now have 2 commits
$ git push --force TheMightyMadman HEAD:add_ads7828
# You may have a different name for the remote which is your fork of our Linux repo

This was very useful, thank you! I've used this to fix the original configuration commit, and also add an entry to bcm2711_rt_defconfig. Noted regarding the 80-character README line limit, I'll make the appropriate changes.

I've now fixed the line lengths in the README file, and we're down to the two required commits.