Bug fix: endpoint numbers were computed as per-interface positions, but
xhcid keys endpoints by GLOBAL index across all interfaces of the
configuration. On two-interface ACM devices (comm interrupt-IN first),
the driver opened (interrupt-IN, bulk-IN) as (bulk_in, bulk_out) — read
from the interrupt endpoint and wrote to the IN endpoint. Endpoints are
now counted across all interfaces in configuration order, exactly as
xhcid's PortState::get_endp_desc does.
P6-A expansion (Linux 7.1 cdc-acm.c reference):
- SEND_BREAK (0x23) control request
- SERIAL_STATE monitoring: poll the comm interface's interrupt-IN
endpoint on a dedicated thread, parse the 8-byte header + 2-byte UART
state bitmap (CDC 1.1 6.3.5): DCD/DSR/break/RI/framing/parity/overrun,
log transitions
- scheme gains a read-only 'state' file reporting the current line
state (dcd=.. dsr=.. ...) for getty/terminal consumers
Verified: cargo check -Z build-std --target x86_64-unknown-redox clean,
no new warnings. Runtime validation needs an ACM device (QEMU has no
CDC ACM emulation; FTDI/Arduino on bare metal or passed through).
Cross-compile error: from_bits_truncate requires u8 but
O_STAT/O_RDWR are usize. Cast with 'as u8'.
Applied to all 4 scheme wrappers: acmd, ftdi, ecmd, usbaudiod.
Cross-referenced with Linux 7.1 tty_port_register_device() pattern.
New scheme.rs module:
- AcmScheme implements SchemeSync with Mutex-wrapped XhciEndpHandle
- openat(): root dir listing + device file open (O_RDWR)
- read(): USB bulk IN → scheme client (getty, terminal)
- write(): scheme client → USB bulk OUT
- close(): decrements open count
- fsync(): no-op
main.rs:
- #[cfg(target_os = redox)]: Socket::create() + register scheme
under /scheme/ttys/usbACM_<port_id>, process requests with
handle_scheme_mut() in event loop
- #[cfg(not(target_os = redox))]: stdout fallback for testing
This enables getty to open /scheme/ttys/usbACM_<N> as a serial
console on USB CDC ACM devices — the driver is now a proper
Redox scheme service, not just a stdout debugging tool.
Pattern replicable for redbear-ftdi (same scheme:ttys), redbear-ecmd
(scheme:net), and redbear-usbaudiod (scheme:audio).
vasilito