Rockchip RK817 (PineTab2 PMIC)

Identity


Part	Rockchip RK817
Role	System PMIC: DCDC/LDO regulators, RTC, 5 V charger path, fuel gauge, audio codec, boost/OTG switch
Bus / address	`i2c0` addr `0x20`
GPIO / IRQ	`GPIO0_A3`, level-low PMIC interrupt
PineTab2 battery node	`simple-battery`, 6000 mAh design capacity, 4.3 V constant-charge voltage
Linux reference	`drivers/power/supply/rk817_charger.c`
Register map reference	`include/linux/mfd/rk808.h`
DTS reference	`rk3566-pinetab2.dtsi`

Status — ◐ partial

The FreeBSD RK8xx PMIC core already knows the RK817 family and regulator layout. This repo now adds a PineTab2-safe battery/charger monitor: src/sys/dev/iicbus/pmic/rockchip/rk817_battery.c attaches from the RK8xx PMIC core when the charger child exists, reads the gas-gauge and charger registers, and exposes dev.rk8xx.N.rk817_* sysctls.

This is intentionally read-only. It does not program PMIC_CHRG_OUT, PMIC_CHRG_IN, GG_CON, relax thresholds, coulomb-counter initial state, or NVRAM. Linux does all of that during probe, but on an unbenched tablet the first FreeBSD pass should answer “what did firmware leave us?” before it starts changing charge limits.

Driver Surface

Sysctl	Meaning
`rk817_present`	`PMIC_CHRG_STS.BAT_EXS`
`rk817_online`	`SYS_STS.PLUG_IN_STS`
`rk817_status`	Decoded charger state string
`rk817_capacity_pct`	`Q_PRES / Q_MAX`, falling back to the DT design capacity
`rk817_voltage_uv` / `rk817_current_ua`	Battery voltage/current using Linux’s RK817 calibration math
`rk817_usb_voltage_uv` / `rk817_sys_voltage_uv`	Input and system rail voltage readouts
`rk817_chrg_out`, `rk817_chrg_in`, `rk817_chrg_term`, `rk817_chrg_sts`	Raw charger control/status registers
`rk817_adc_config0`, `rk817_adc_config1`, `rk817_gg_con`, `rk817_gg_sts`	Raw gas-gauge configuration/status
`rk817_dbg_reg` / `rk817_peek`	Read-only register peek for bench hypotheses
`rk817_dump`	Write non-zero to emit one decoded dmesg line

The patch into FreeBSD’s RK8xx core is deliberately small: patches/sys/dev/iicbus/pmic/rockchip/rk8xx.c.patch includes rk817_battery.h and calls rk817_battery_attach(sc->dev) only when sc->type == RK817. patches/sys/conf/files.arm64.patch builds the new file whenever rk8xx is in the kernel.

First Bench Predicate

After the tablet boots:

dmesg | grep -i rk817
sysctl dev.rk8xx.0 | grep rk817
sysctl dev.rk8xx.0.rk817_dump=1

The useful first proof is not “charging works”; it is:

rk817_id_msb/rk817_id_lsb read as a plausible RK817 ID.
rk817_present=1.
rk817_voltage_uv is in the single-cell Li-ion range.
rk817_res_div=1, matching the PineTab2 DTS 10000 micro-ohm sense resistor.
rk817_chrg_sts and rk817_sys_sts move when USB-C power is connected or removed.

Only after those are boring should the driver grow write-side support for ADC enables, charger limits, fuel-gauge initialization, and Type-C role handoff.

Open Work

Compile-test in a full PINETAB2 kernel once Coppice or honor is stable.
Decide whether to keep the read-only monitor as a separate file or fold RK817 into a more general RK8xx battery/charger layer.
Add controlled write-side initialization from Linux: ADC enables, GG_CON, relax thresholds, PMIC_CHRG_OUT, PMIC_CHRG_IN, and Q_INIT.
Wire the PMIC interrupt instead of polling.
Keep the RK817 codec/audio path separate; the charger monitor should not become a general PMIC kitchen sink.