Re: [PATCH] platform/x86: Add intel_bytcrc_pwrsrc driver

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On Sat, Mar 4, 2023 at 12:19 AM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
> Add a new driver for the power-, wake- and reset-source functionality
> of the Bay Trail (BYT) version of the Crystal Cove PMIC.
> The main functionality here is detecting which power-sources (USB /
> DC in / battery) are active. This is normally exposed to userspace as
> a power_supply class charger device with an online sysfs attribute.
> But if a charger is online or not is already exposed on BYT-CRC devices
> through either an ACPI AC power_supply device, or through a native driver
> for the battery charger chip (e.g. a BQ24292i).
> So instead of adding duplicate info under the power_supply class this
> driver exports the info through debugfs and likewise adds debugfs files
> for the reset- and wake-source info / registers.
> Despite this driver only exporting debugfs bits it is still useful to
> have this driver because it clears the wake- and reset-source registers
> after reading them. Not clearing these can have undesirable side-effects.

Hmm... Why is the existing regmap debugfs not enough? OK, maybe adding
something (clearing bits) to the actual CRC PMIC driver.
(You also can add a write callback so regmap will provide the write
access to the registers).

> Specifically if the WAKESRC register contains 0x01 (wake by powerbutton)
> on reboot then the firmware on some tablets turns the reboot into
> a poweroff. I guess this may be necessary to make long power-presses turn
> into a poweroff somehow?

Have not a doc at hand. Next week I will try to dig into it to see if
there is anything regarding it.

With Best Regards,
Andy Shevchenko

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