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usb: recognize and configure hubs, power downstream ports (B4a)

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First slice of hub support (docs/usb-hub.md), handled IN the xhci-bus
because a device behind a hub is reached by the CONTROLLER via a route
string in its slot context — topology only exists inside the driver
that owns the controller. When the scan enumerates a class-9 device it
now calls setupHub: read the hub descriptor for the downstream port
count and TT arrangement, tell the controller the slot is a hub
(Configure Endpoint with the slot add-flag sets the Hub bit, Number of
Ports, and MTT/TT-Think-Time per xHCI 4.6.6), SET_HUB_DEPTH for a
SuperSpeed hub so it can compose route strings, and SET_FEATURE
PORT_POWER every downstream port.

The Device gains topology fields (route string, root port, parent hub
slot/port for the TT) and buildAddressInputContext now fills them, so
the Address Device path is ready for downstream devices — those are
enumerated in B4b. A root-port device gets route 0 and its own port as
the chain root, unchanged behavior.

Verified in QEMU with a hub on a second controller and a device behind
it (a usb-hub QEMU case, since the boot controller's auto-assigned
devices collide on the low ports): 'hub slot 1: 8 downstream ports
powered (USB2 single-TT)'. Full suite 89/89. The user's SuperSpeed
Genesys hub is the real-hardware target, flagged separately (QEMU's
USB2 hub doesn't model the compound USB3 hub).
This commit is contained in:
Daniel Samson
2026-07-21 21:56:59 +01:00
parent 983b4ed05a
commit 92b03b8d07
4 changed files with 326 additions and 4 deletions
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system/drivers/usb-xhci-bus/usb-xhci-bus.zig
+15
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@@ -235,6 +235,21 @@ fn bringUpPort(manager: runtime.ipc.Handle, engine: *library.Controller, port: u
interface.registered_device_id = registered;
}
}
// A hub (class 9) is bus infrastructure the bus drives itself: configure it
// and power its downstream ports (docs/usb-hub.md). Its interfaces are still
// reported above, but no external class driver binds it.
if (deviceIsHub(usb_device)) _ = engine.setupHub(usb_device);
}
/// Whether an enumerated device is a hub — class 9 at the device or the
/// interface level (a hub's single interface is class 9/0/0).
fn deviceIsHub(usb_device: *const library.Device) bool {
if (usb_device.device_descriptor.device_class == @intFromEnum(usb_ids.Class.hub)) return true;
for (usb_device.interfaces[0..usb_device.interface_count]) |interface| {
if (interface.class == @intFromEnum(usb_ids.Class.hub)) return true;
}
return false;
}
/// Tear down whatever was on `port` after an unplug: report each registered