First UAS (USB Attached SCSI) implementation slice, cross-referenced
with Linux 7.1 drivers/usb/storage/uas.c and uas-detect.h.
protocol/uas.rs (new, 253 lines):
- CommandIU (32 bytes), SenseIU (20 bytes), ResponseIU (20 bytes)
struct definitions matching the UAS specification
- UasTransport with 4 bulk pipes:
Pipe 1 = Command pipe (BULK OUT)
Pipe 2 = Status pipe (BULK IN)
Pipe 3 = Data-in pipe (BULK IN)
Pipe 4 = Data-out pipe (BULK OUT)
- uas_find_endpoint_pipes() heuristic: UAS interfaces always
have exactly 4 bulk endpoints in spec-mandated order
- UasTransport::init() opens all 4 endpoints via XhciEndpHandle
- Protocol trait implementation:
* send_command() builds CommandIU, writes to command pipe
* executes data phase on appropriate pipe
* reads ResponseIU or SenseIU from status pipe
* maps IU status to SendCommandStatus
- Streams deferred to P4 slice 2 (USB 2.0 sequential, no
CBW/CSW overhead)
protocol/mod.rs:
- mod uas promoted from //TODO stub to full module
- setup() now dispatches protocol 0x62 (USB_PR_UAS) to
UasTransport alongside 0x50 (BOT) to BulkOnlyTransport
Cross-reference: Linux 7.1
- drivers/usb/storage/uas.c: uas_configure_endpoints()
- drivers/usb/storage/uas-detect.h: uas_find_endpoints()
- drivers/usb/storage/uas.c: struct uas_dev_info pipe model
- include/uapi/linux/usb/ch11.h: USB_PR_UAS = 0x62
This means USB 3.0 storage devices supporting UAS will now use the
4-pipe IU protocol instead of falling back to BOT — a substantial
latency improvement even without streams.
Red Bear OS
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