feat(cpufreq): RK3588 ondemand CPU DVFS with voltage calibration

components/axcpu/src/aarch64/init.rs

@@ -118,6 +118,19 @@ pub fn init_trap() {
     #[cfg(feature = "uspace")]
     {
         CNTKCTL_EL1.modify(CNTKCTL_EL1::EL0VCTEN::TrappedNone + CNTKCTL_EL1::EL0PCTEN::TrappedNone);
+        // Start this CPU's free-running PMU cycle counter and let EL0 read it, so
+        // `PMCCNTR_EL0` yields real cycle counts at both EL1 and EL0. This is the
+        // exact-frequency oracle the DVFS calibration reads in-kernel and that
+        // `cpuprobe`'s `mhz_pmc` reads from userspace (both were 0/trapping before,
+        // because these registers were only ever set on the lazy perf_event_open
+        // path). Guarded on PMUv3 being present; a live system-wide `perf stat -e
+        // cycles` may momentarily reset/disable this shared counter, which is fine
+        // for a boot/idle calibration.
+        if crate::pmu::probe().is_some() {
+            crate::pmu::init_cpu();
+            crate::pmu::cycles::configure(false, false);
+            crate::pmu::cycles::enable();
+        }
         barrier::isb(barrier::SY);
     }
     unsafe extern "C" {

docs/rk3588-cpufreq.md

@@ -0,0 +1,62 @@
+# RK3588 CPU DVFS (cpufreq)
+
+Feature-gated ondemand CPU frequency/voltage scaling for the Orange Pi 5 Plus
+(RK3588). It is off by default in the generic and QEMU builds — the
+`ax-driver/rk3588-cpufreq` feature compiles the driver to no-ops there — and is
+enabled on the Orange Pi board build.
+
+## What it does
+
+The RK3588 CPU clock is a voltage-coupled PVTPLL. An **ondemand** governor scales
+each of the three CPU clusters (A55 little `cpu0-3`, two A76 big pairs `cpu4-5` /
+`cpu6-7`) between OPPs by pairing an SCMI PVTPLL ring target with a PMIC rail
+voltage:
+
+- **A76** uses the full voltage lever — its RK8602/RK8603 rails read back over I2C,
+  so every voltage write is confirmed and the SCMI clock rate is read back before an
+  OPP is committed.
+- **A55** is **ring-only**: its RK806 rail cannot be read back (a MISO hardware
+  limit), so it stays on the boot-confirmed 675 mV rail and scales only its SCMI
+  ring. 675 mV over-volts every A55 ring ≤ 1008 MHz, so it can never undervolt.
+
+It is **fail-safe**: if either PMIC bus does not come up at boot, `GOV_READY` stays
+`false` and every cluster is left on its boot OPP (no scaling).
+
+## Enable and build
+
+The feature is enabled in both Orange Pi 5 Plus build configs:
+
+- `test-suit/starryos/board-orangepi-5-plus/build-aarch64-unknown-none-softfloat.toml`
+  — the config the **board CI runner** actually builds, so the standard board
+  test entry compiles, boots and runs the governor on real hardware:
+
+  ```bash
+  cargo xtask starry test board --board orangepi-5-plus
+  ```
+
+  Every case there boots this kernel; a governor-induced boot panic/hang trips the
+  cases' `panic` fail-regex, so the board CI regression-guards the feature.
+- `os/StarryOS/configs/board/orangepi-5-plus.toml` — the general board build
+  template (for a full-board `max_cpu_num` build outside CI).
+
+To enable it in a custom build, add `"ax-driver/rk3588-cpufreq"` to that config's
+`features` list.
+
+## Observable verification
+
+At boot (early init, before the console handoff) the driver logs the rail bring-up
+and governor arming to the serial console:
+
+```
+cpufreq: A55 rail boot voltage = <uV> uV
+cpufreq: A55 <before>-><after>, A76 <before>-><after> MHz
+cpufreq: ondemand governor armed (both PMIC buses up)
+```
+
+Under load, per-cluster OPP transitions are logged
+(`gov: A76b0 peak=<n>% opp <i>-><j> = <mhz> MHz @ <mv> mV`), and the delivered
+frequency can be read exactly with `cpuprobe`'s `mhz_pmc` (the PMU cycle counter is
+enabled at boot): a busy cluster climbs toward its top OPP, an idle cluster sheds
+back down one step at a time. The companion `apps/starry/sysbench-board` harness
+(PR #1658) drives an all-core load and captures these numbers against a Linux
+baseline.

drivers/ax-driver/Cargo.toml

@@ -136,6 +136,12 @@ rockchip-soc = [
     "dep:rdif-reset",
     "dep:rockchip-soc",
 ]
+# RK3588 fixed-OPP-at-boot CPU DVFS (voltage-free rung): raises the CPU cluster
+# clocks via the SCMI seam at probe time. Board-only policy; keep it opt-in.
+rk3588-cpufreq = [
+    "rockchip-soc",
+    "dep:arm-scmi-rs",
+]
 rockchip-pm = ["rockchip-soc", "dep:rdif-power", "dep:rockchip-pm"]
 list-pci-devices = ["pci"]
 pci-list-devices = ["list-pci-devices"]

drivers/ax-driver/src/lib.rs

@@ -95,6 +95,44 @@ pub mod usb;
 #[cfg(virtio_dev)]
 pub mod virtio;
 
+/// RK3588 CPU DVFS ondemand governor, exposed as a stable, arch-neutral entry
+/// the kernel can drive from a periodic task without knowing the SoC specifics.
+///
+/// The governor's *policy + apply* live in the (arch-specific) cpufreq driver,
+/// but its *loop* — sleeping between samples and reading the per-CPU busy
+/// counters — cannot live in this crate: ax-driver sits below ax-task/ax-hal in
+/// the dependency graph, so spawning a task here would be a cyclic dependency.
+/// The kernel therefore owns the loop and calls [`cpufreq::governor_poll`] each
+/// tick. When the DVFS feature is off these are no-ops so callers stay generic.
+pub mod cpufreq {
+    #[cfg(feature = "rk3588-cpufreq")]
+    pub use crate::soc::rockchip::cpufreq::{
+        calibrate_cluster, calibrate_wanted, governor_period_ms, governor_poll, governor_wanted,
+    };
+
+    /// Feature-off stub: no governor, so the kernel never spawns its task.
+    #[cfg(not(feature = "rk3588-cpufreq"))]
+    pub fn governor_wanted() -> bool {
+        false
+    }
+    /// Feature-off stub.
+    #[cfg(not(feature = "rk3588-cpufreq"))]
+    pub fn governor_period_ms() -> u64 {
+        100
+    }
+    /// Feature-off stub.
+    #[cfg(not(feature = "rk3588-cpufreq"))]
+    pub fn governor_poll(_busy: &[u64]) {}
+    /// Feature-off stub: no calibration.
+    #[cfg(not(feature = "rk3588-cpufreq"))]
+    pub fn calibrate_wanted() -> bool {
+        false
+    }
+    /// Feature-off stub.
+    #[cfg(not(feature = "rk3588-cpufreq"))]
+    pub fn calibrate_cluster(_cluster_idx: usize, _intended_cpu: usize) {}
+}
+
 #[cfg(feature = "pci")]
 pub use binding_info::PciIrqRequirement;
 pub use binding_info::{BindingInfo, BindingIrq, BindingIrqBinding, BindingIrqSource, FdtIrqSpec};

drivers/ax-driver/src/soc/mod.rs

@@ -15,8 +15,8 @@
 #[cfg(feature = "pinctrl")]
 mod fixed_regulator;
 #[cfg(feature = "rockchip-soc")]
-mod rockchip;
-#[cfg(feature = "rockchip-dwmmc")]
+pub(crate) mod rockchip;
+#[cfg(any(feature = "rockchip-dwmmc", feature = "rk3588-cpufreq"))]
 pub mod scmi;
 #[cfg(feature = "starfive-soc")]
 mod starfive;