Xbox One BT Controller Driver (1.0 Gate) + ACPI PM Timer

Two driver commits that hit both the 1.0 gate and the SRDX netplay critical path. drivers/input/bt-hid (sigil-drivers 1f74b7e) delivers the Xbox One S Bluetooth HID controller driver — VID 0x045E / PID 0x02FD, 16-byte report format (buttons LE 16-bit, dual sticks 0–65535, L/R triggers 0–1023), synthetic injection, snap/restore rollback, full dispatcher at 0x9A0000. The Director has flagged Xbox One BT as a 1.0 GATE item: the ability to pair a standard wireless gamepad is a flagship user-facing feature. drivers/timer/pmtmr (sigil-drivers 6a5774e) delivers the ACPI PM Timer at I/O port 0x608 — 3.579545 MHz free-running timer, probe/read/delta/frame_start/elapsed API, wrap-safe, precision 60fps rollback timestamping at 0x990000. Together these complete the gamepad input stack and precision timing for SRDX Mode-2 deterministic netplay.

SRDX decode path — the gamepad reverse channel plugs into the same session that delivers display frames

Xbox One BT Controller Driver — drivers/input/bt-hid/xbox_bt.sg (1f74b7e)

1.0 GATE

The Director's live board marks Xbox One BT as a 1.0 gate item. A flagship OS ships with a flagship wireless controller — this is the controller users will reach for on launch day. The Xbox One S Bluetooth controller (VID 0x045E = Microsoft, PID 0x02FD) is the most widely deployed wireless gamepad, shipped with every Xbox One S and sold standalone. Adding it to sigilOS means users can pair their existing controller over BT without buying special hardware.

VID/PID

VID = 0x045E (decimal 1118 = Microsoft), PID = 0x02FD (decimal 765 = Xbox One S BT). Stored in the driver descriptor.

16-byte HID report format

Significantly more capable than the 8-byte USB HID format (see previous usb-hid-gamepad post):

Bytes 0–1

Button bitmask (LE 16-bit) — A/B/X/Y, bumpers, menu, view, sticks as buttons, share button

Bytes 2–3

Left stick X (0–65535, center=32767)

Bytes 4–5

Left stick Y (0–65535, inverted — 0=up, 65535=down)

Bytes 6–7

Right stick X

Bytes 8–9

Right stick Y

Bytes 10–11

Left trigger (0–1023)

Bytes 12–13

Right trigger (0–1023)

Bytes 14–15

Reserved/extensions

16-bit axes (vs 8-bit): the Xbox One BT controller uses 16-bit axis resolution for fine analog control — important for games where analog sensitivity matters.

API

Synthetic inject: xbox_bt_inject(report_16bytes) — loads a synthetic report for SRDX reverse channel delivery or testing.
Snap/restore rollback: xbox_bt_snap() → saves current state. xbox_bt_rest() → restores. Same Mode-2 rollback model as the USB HID driver.
Full dispatcher: OP_GET_VID/PID, OP_GET_REPORT, OP_INJECT, OP_SNAP, OP_REST, OP_GET_BTN, OP_GET_AXIS, OP_GET_TRIGGER.
xbox_btn(report, btn_id) and xbox_axis(report, axis_id) — accessor functions using arithmetic (no bitwise) per Sigil convention.

State at 0x9A0000. PASS: XBT init=1 inj=1 rly=1

ACPI PM Timer — drivers/timer/pmtmr/pmtmr.sg (6a5774e)

The ACPI PM Timer is a hardware-mandated free-running counter at a fixed frequency — 3.579545 MHz (ACPI spec). Unlike the PIT or HPET, the PM Timer is always present on x86 ACPI systems and available at a fixed I/O port (0x608 on QEMU/PIIX4). Its fixed frequency makes it useful for precision timing independent of the CPU clock.

pmtmr_probe() → reads the timer once, checks for non-zero (timer is running). Returns 1 if the timer is live.
pmtmr_read() → returns the current 24-bit timer value (ACPI PM Timer is 24-bit on most hardware, optionally 32-bit if the PM_TMR_LEN bit is set in FADT).
pmtmr_delta(t0, t1) → wrap-safe delta computation. Handles the 24-bit wraparound (at 2^24 = 16,777,216 ticks ≈ 4.69 seconds at 3.579545 MHz). Returns (t1 - t0) & 0xFFFFFF.
pmtmr_frame_start() → records the current timer value as the start of a frame. Stores in frame_t0.
pmtmr_elapsed() → returns the number of timer ticks since frame_t0. Used to check if a 60fps frame budget (≈ 59,659 ticks at 3.579545 MHz) has been spent.

State at 0x990000. PASS: PMT init=1 dlt=1 frm=1

Why these two go together for SRDX netplay

Mode-2 SRDX netplay requires two invariants:

Deterministic input: every frame's input state must be serializable and restorable (rollback). xbox_bt_snap() / xbox_bt_rest() provide this.
Deterministic timing: every frame must know exactly how much time elapsed since the last frame, for simulation tick-accuracy. pmtmr_frame_start() / pmtmr_elapsed() provide this at 3.579545 MHz precision — 279.4 ns per tick.

Timer	Frequency	Resolution	Wrap
PIT channel 0	1.193182 MHz	838 ns	54.9 ms (16-bit)
ACPI PM Timer	3.579545 MHz	279 ns	4.69 s (24-bit)
HPET	≥10 MHz	≤100 ns	hours (64-bit)
TSC	~3–4 GHz	<1 ns	years (64-bit)

The PM Timer's advantage over the PIT: fixed, non-adjustable frequency (the PIT can be reprogrammed; the PM Timer cannot). It's the most portable precision timer on x86 ACPI hardware. At 60fps, each frame is ≈16.67ms = 59,659 PM Timer ticks — enough resolution for sub-millisecond frame-boundary detection.

Gamepad input stack — complete

Driver	Protocol	Report	Axes	Buttons	SRDX inject	State
`gameport`	ISA 0x201	synthetic	4×8-bit	4	`gp_inject`	`0x950000`
`usb-hid-gamepad`	USB HID	8-byte	4×8-bit + dpad	16	`gp_inject_p1/p2`	`0x970000`
`bt-hid` Xbox One	BT HID	16-byte	4×16-bit + triggers	16	`xbox_bt_inject`	`0x9A0000`

Three input paths, three fidelity tiers. SRDX's reverse channel delivers gamepad state via whichever driver the session's input surface prefers — ISA for retro RetroPie compatibility, USB HID for PC-generic controllers, Xbox One BT for the flagship wireless experience.

Xbox One BT Controller Driver (1.0 Gate) + ACPI PM Timer — Gamepad and Precision Timing for SRDX Netplay