Add USB Host (XHCI) driver and MSC support for Tegra X1 - #2
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Implements USB SSD as a third emuMMC storage backend alongside the
existing SD-partition and file-based paths. When usb_enabled=1 and
usb_sector=<lba> are set in the emummc INI, Atmosphere boots from
the USB drive rather than an SD card partition.
New files:
bdk/usb/usbh.c — XHCI host controller driver (pure MMIO,
no firmware blob); host clocks, PHY init
(mirrored from xusbd.c), port reset, ENABLE_SLOT,
ADDRESS_DEVICE, CONFIGURE_EP, control/bulk xfers.
Ring wrap follows XHCI §4.9.3: link TRB written
with current PCS before PCS is toggled.
bdk/usb/usbh.h — XHCI TRB constants, ring/context structs, public API.
bdk/usb/usbh_msc.c — BOT host driver: CBW→data→CSW, SCSI subset
(TEST_UNIT_READY, INQUIRY, READ_CAPACITY(10),
READ(10)), sector-chunked reads.
bdk/usb/usbh_msc.h — usbh_msc_t struct and declarations.
bdk/usb/usbh_hub.c — Hub class driver (powers ports, resets downstream
port); full multi-slot re-enumeration is TODO —
returns USB_ERROR_INIT with fallback message.
bootloader/storage/usb_blkdev.c — thin block-device wrapper over usbh_msc.
bootloader/storage/usb_blkdev.h — usb_blkdev_t and declarations.
Modified files:
bdk/memory_map.h — USBH_BULK_IN/OUT_BUF_ADDR + USBH_BULK_BUF_SZ.
bdk/usb/usb_t210.h — XUSB_HOST_CONFIGURATION / HOST_CONFIGURATION_EN_FPCI.
bootloader/storage/emummc.h — usb_enabled + usb_sector fields in emummc_cfg_t.
bootloader/storage/emummc.c — INI parsing + routing branches for USB path.
bootloader/main.c — early emummc_load_cfg() + conditional usbh_init().
https://claude.ai/code/session_01BAVie7bqN6o7NEcR5GSrr6
Verification pass against the XHCI spec, T210 TRM and Linux xhci-tegra found one missing hard requirement and several fatal bugs: Missing requirement: - The XUSB host complex is driven by an integrated Falcon microcontroller; the xHCI interface does not function until its firmware is loaded and booted (unlike the XUSB device block, which is pure hardware). Add the CSB/L2IMEM firmware loader (mirrors Linux xhci-tegra.c), reading the standard tegra21x XUSB firmware from sd:/bootloader/sys/xusbfw.bin into a resident DRAM buffer. Also program the XUSB_FALCON clock (204MHz). Fatal fixes: - CLK_SOURCE_XUSB_CORE_HOST is 0x600, not 0x614 (TRM CAR layout around the existing 0x608/0x60C/0x610 defines). - Runtime base had interrupter 0 offset applied twice (rt_base += 0x20 on top of 0x20-based register macros), so ERSTBA/ERDP landed on interrupter 1 and the event ring was never armed. - Input context EP entries were indexed by DCI instead of DCI-1, so ADDRESS_DEVICE read a zeroed EP0 context. - VBUS_ID write OR-ed in ID_OVR GND (value 0) without clearing the OVR field, leaving ID floating and the controller out of host role. - IOC was set on Setup/Data/Status TRBs but only 1-2 events were consumed, desynchronizing the event ring after the first control transfer. IOC is now only on the final TRB (one event per transfer). - Ring wrap mid-control-transfer overwrote the Link TRB (no per-TRB wrap check); replaced with a _trb_alloc helper that handles wrap per enqueue. - Unsolicited Port Status Change Events were consumed as command/transfer completions; they are now filtered out. - 1MB bulk chunks overflowed the 17-bit TRB transfer length field; chunk at 64KB. - emummc_storage_read() USB branch returned 0-on-success into a 1-on-success convention (every successful read reported failure). - emummc_storage_write() had no USB branch and could fall through to the SD-offset path; added a write path (WRITE10 through usbh_msc_write). Robustness/compat: - Parse the configuration descriptor for bConfigurationValue and the real bulk endpoint addresses/max-packet (devices are not all EP1/EP1); use dynamic DCIs for doorbells and endpoint contexts. - Allocate XHCI scratchpad buffers per HCSPARAMS2 (firmware requires them). - Wait for USBSTS.CNR before and after HC reset. - Preserve-mask PED and W1C bits on PORTSC writes (writing PED=1 disables the port); acknowledge CSC/PRC after port reset and check PED. - Source 5V onto VBUS via regulator_5v_usb_src_enable() for the handheld/OTG path (Icosa); dock supplies downstream power itself. - EP0 max packet 64 for FS devices (8 only for LS). - usbh_msc.c was missing the usbd.h include for USB_RES_*/USB_ERROR_*. https://claude.ai/code/session_01BAVie7bqN6o7NEcR5GSrr6
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This PR adds a complete USB Host (XHCI) driver implementation for Tegra X1, enabling the bootloader to read from USB Mass Storage Class (MSC) devices connected via the dock's USB port.
Summary
Implements a minimal but functional XHCI host controller driver that supports device enumeration, control transfers, and bulk I/O operations. Includes a USB MSC (Mass Storage Class) driver using the BOT (Bulk-Only Transport) protocol and a hub class driver stub for future multi-device support. Integrates USB storage as an alternative emuMMC backend alongside existing SD card and file-based options.
Key Changes
Core XHCI Host Driver (
bdk/usb/usbh.c)USB MSC Driver (
bdk/usb/usbh_msc.c)Hub Class Driver (
bdk/usb/usbh_hub.c)Block Device Abstraction (
bootloader/storage/usb_blkdev.c/h)Integration
emummc.cto support USB as an emuMMC backend with configurable LBA offsetmain.cto initialize USB host on boot when configuredmemory_map.husb_t210.hwith XUSB host register definitionsemummc.hto include USB configuration fieldsImplementation Details
https://claude.ai/code/session_01BAVie7bqN6o7NEcR5GSrr6