On 26/04/2016 at 16:31:46 +0200, Jeppe Ledet-Pedersen wrote :

quoted

Good catch, I didn't look at this patch but it includes a lot of code
that should be going to the RTC driver.
If trickle charging is not enabled, I guess the RTC will not charge its
backup battery.

Thank you for the comments.

Alexandre is correct. If the "cypress,charge-enabled" property is
present, the internal 80 uA trickle charger is enabled to charge a
backup capacitor on the VBAK pin.

Do you want more code than the trickle charger setup moved to the RTC
driver?

I guess the 32k oscillator could go in the rtc driver too.

quoted

quoted

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+- cypress,charge-fast: enable fast (1 mA) charging

What does fast mean?

Fast charging means charging with 1 mA instead of 80 uA. The wording is
from the datasheet, but I agree it should be renamed to something that
better explains what the difference is.

quoted

quoted

I think it is time for a common binding here. There's all sorts of 
variations on setting the charge current in bindings. Add something like 
"charge-current-microamp" in power_supply.txt and use it here. Then 
1000uA implies "fast charge".

Well, this is not a power supply, it is an RTC.

I think both properties should got to the RTC subdevice and be parsed in
the RTC driver.

The backup capacitor is primarily used to supply current to the RTC, but
a couple of other registers are also battery-backed (watchdog reset
cause, event counter), so I put the charger setup in the main MFD file.

If you prefer, I can move them both to the RTC driver?

I would prefer unless you think that many people are not using the RTC
while still using the watchdog (I'd say that is not the case).

quoted

Note that for trickle charging, we currently have the following
properties:
 - trickle-resistor-ohms
 - trickle-diode-disable
 - abracon,tc-diode
 - abracon,tc-resistor

abracon,tc-resistor can be replaced by trickle-resistor-ohms, I'll make
a patch but abracon,tc-diode allows to select a diode type (and in
particular a voltage drop).

I think we could add a trickle-current-microamp like you suggested and
trickle-diode-disable can be reused.

So replace "cypress,charge-enabled/charge-fast" with
"trickle-current-microamp" and a check for 0/80/1000 uA?

Yeah, seems fine.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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