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RK818/816 Fuel Gauge Print Information Description

Release Version: 1.0

Author Email: chenjh@rock-chips.com

Date: 2018.05.28

Security Level: Public

Preface

Overview

RK818/RK816 provide built-in fuel gauge and charge functionality, i.e., battery capacity detection and battery charging management. The two chips implement these functions very similarly. This document uses RK818 as an example to introduce important information printed by the driver at various stages. The print information for RK816 is similar and can be referenced directly, without a separate document.

Product Versions

Chip NameKernel Version
RK818, RK816Linux 4.4

Intended Audience

This document (guide) is mainly applicable to the following engineers: Technical support engineers Software development engineers

Revision History

DateVersionAuthorDescription
2018.05.28V1.0Chen JianhongInitial version

[TOC]

Charger/OTG Detection​

Driver Files​

drivers/power/rk818_charger.c

This driver mainly implements charger/OTG plug-in/out event detection and charging current configuration. Print information uses "rk818-charger: " as a prefix for easy identification. "ac", "usb", "dc", "otg" in the prints represent different devices; 1 indicates connected, 0 indicates disconnected. Note: The PMIC itself cannot detect charger/OTG plug-in/out events; charger type detection relies on USB notification chain messages.

Probe Phase​

DC charger registration status:

rk818-charger: support dc
rk818-charger: not support dc

Register type-c port charger notification chain:

rk818-charger: register typec extcon evt notifier

Register traditional usb port charger notification chain:

rk818-charger: register bc evt notifier

Device connection status at the end of probe:

rk818-charger: ac=1, usb=0, dc=0, otg=0

Driver version number:

rk818-charger: driver version: 2.0

Running Phase​

Charger/OTG device plug-in/out events from USB notification chain:

rk818-charger: receive bc notifier event: DISCNT	// Charger unplugged
rk818-charger: receive bc notifier event: USB		// Computer charger plugged in
rk818-charger: receive bc notifier event: AC		// Standard charger plugged in
rk818-charger: receive bc notifier event: CDP1.5A	// CDP type charger plugged in
rk818-charger: receive bc notifier event: UNKNOWN	// Unrecognized charger plugged in
rk818-charger: receive bc notifier event: OTG ON	// OTG plugged in
rk818-charger: receive bc notifier event: OTG OFF	// OTG unplugged
rk818-charger: detect dc charger in					// DC plugged in
rk818-charger: detect dc charger out				// DC unplugged

The PMIC itself cannot determine the charger type but can detect whether a charging device is plugged in:

rk818-charger: pmic: plug out
rk818-charger: pmic: plug in

5V power supply changes when plugging/unplugging OTG:

rk818-charger: disable otg5v
rk818-charger: enable otg5v

After each charger/OTG plug-in/out, device and current information is updated:

rk818-charger: ac=1 usb=0 dc=0 otg=0 v=4200 chrg=1000 input=1800 virt=0

Suspend Phase​

5V power supply changes for OTG during suspend:

rk818-charger: suspend: otg 5v on
rk818-charger: suspend: otg 5v off

Shutdown Phase​

Connection status of each device at shutdown:

rk818-charger: shutdown: ac=1 usb=0 dc=0 otg=0

Battery Capacity Detection​

Driver Files​

drivers/power/rk818_battery.c
drivers/power/rk818_battery.h

This driver mainly implements fuel gauge functionality, providing a set of drivers for battery capacity information statistics. Print information uses "rk818-bat: " as a prefix for easy identification.

Probe Phase​

When powering on for the first time with a battery connected, there is a "first on" prompt:

rk818-bat: first on: dsoc=24, rsoc=24 cap=960, fcc=4000, ov=3840

When abnormal shutdown (e.g., continuous power drain after crash) causes coulomb counter anomalies, a forced coulomb counter calibration is performed at next boot:

rk818-bat: system halt last time... cap: pre=2400, now=120

When U-Boot has already initialized the fuel gauge, the kernel fuel gauge driver can skip part of the initialization to prevent duplicate initialization:

rk818-bat: initialized yet..

Coulomb counter initial state during probe:

rk818-bat: dsoc=32 cap=1000 v=3780 ov=3900 rv=3890 min=25 psoc=32 pcap=1000

Fuel gauge version number:

rk818-bat: driver version 7.1

Running Phase​

When the battery level changes, the driver reports to the framework with the following prints. The first line shows real-time parameter status; the second line shows parameter states at boot initialization, mainly for debugging:

rk818-bat: changed: dsoc=22, rsoc=24, v=3820, ov=3770 c=1018, cap=960, f=4000, st=cc cv, hotdie=0
rk818-bat: dl=10, rl=12, v=3670, halt=0, halt_n=0, max=0, init=0, sw=0, calib=0, below0=0, force=0

Suspend Phase​

After entering deep sleep, if prolonged standby causes the battery voltage to drop below the shutdown threshold, a PMIC wake-up interrupt is generated, followed by shutdown:

rk818-bat: lower power yet, power off system! v=3350, c=-125, dsoc=0

Shutdown Phase​

Relevant important information is displayed during shutdown:

rk818-bat: shutdown: dl=0 rl=2 c=-1220 v=3460 cap=88 f=4000 ch=1 n=0 mode=1 rest=128
Print meaning: <display soc> <real soc> <current> <voltage> <remaining capacity> <full charge capacity> <has charger> <others ignored...>

About RK816 Fuel Gauge​

The fuel gauge implementation of RK816 is essentially similar to RK818. Both the charger detection and fuel gauge changes are unified in:

drivers/power/rk816_battery.c

The print information content is very similar to RK818, with print information prefixed by "rk816-bat:" for easy identification. Therefore, for the RK816 part, please refer to the RK818 description above.