Enable charging from VBAT pin in Linux

CErik.1 · ‎2021-04-08

Hello,

I would like to enable battery/capacitor charging from the VBAT pin on an STM32MP1 and also change the charging resistor.

That would be VBE and VBRS of PWR_CR3.

What would be the proper way to enable/disable the charging together with the resistor value from Linux and/or U-boot?

The regulator driver managing PWR_CR3 does not mention VBE or VBRS.

Thanks

PatrickF · ‎2021-04-28

Hi,

I think for the moment, these bits are not managed by Device Tree, you could probably modify TF-A for that specific purpose.

Regards.

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Bernard PUEL · ‎2021-08-04

Hello,

A change request is under discussion in ST to implement it in Device tree. For ST this would be required only in TF-A but would you really need to enable the register settings in u-boot or Linux (or TF-a is enough for your need) ?

CErik.1 · ‎2021-08-04

I missed the reply button. See above.

(Unable to delete)

CErik.1 · ‎2021-08-04

Great thanks!

Currently I enable the setting in U-Boot, but any stage is fine (TF-A, U-Boot or Linux) . TF-A would work perfectly fine.

Again thanks!

Bernard PUEL · ‎2021-08-04

Ok thanks for the quick answer.

fyi, in tf-a and optee the function "raw_allowed_access_request()" allows to set these bits.