usb-ids: className/interfaceName helpers; readable device classes in the bus log

The logs read 'class 9/0/0' where they could say 'Hub'. usb-ids gains
className (a device/interface class byte -> 'Hub', 'HID', 'Mass Storage',
...) and interfaceName (a HID boot interface -> 'HID boot keyboard' /
'HID boot mouse'), both host-tested with usb-ids. The bus driver's
enumerate + register lines now read, e.g.:

  port 21 device: Hub vendor 0x05e3 product 0x0626, 1 interface(s)
  port 21 interface 0: Hub (9/0/0) registered as device 47
  port 5 interface 0: HID boot keyboard (3/1/1) registered as device 32

so a real-hardware log is scannable by eye. Full USB case set green
(hub regexes follow the new 'device: <name>' format).

system/devices/usb-ids.zig

@@ -70,6 +70,53 @@ pub const Class = enum(u8) {
     _,
 };
 
+/// A human-readable name for a device/interface class code, for logs. Unknown
+/// codes fall through to "class 0xNN".
+pub fn className(class: u8) []const u8 {
+    return switch (@as(Class, @enumFromInt(class))) {
+        .per_interface => "per-interface",
+        .audio => "Audio",
+        .communications => "Communications",
+        .hid => "HID",
+        .physical => "Physical",
+        .image => "Image",
+        .printer => "Printer",
+        .mass_storage => "Mass Storage",
+        .hub => "Hub",
+        .cdc_data => "CDC Data",
+        .smart_card => "Smart Card",
+        .content_security => "Content Security",
+        .video => "Video",
+        .personal_healthcare => "Personal Healthcare",
+        .audio_video => "Audio/Video",
+        .billboard => "Billboard",
+        .type_c_bridge => "Type-C Bridge",
+        .bulk_display => "Bulk Display",
+        .mctp => "MCTP",
+        .i3c => "I3C",
+        .diagnostic => "Diagnostic",
+        .wireless_controller => "Wireless Controller",
+        .miscellaneous => "Miscellaneous",
+        .application_specific => "Application-specific",
+        .vendor_specific => "Vendor-specific",
+        _ => "Unknown",
+    };
+}
+
+/// A fuller name for a HID interface's (subclass, protocol): "HID boot keyboard"
+/// / "HID boot mouse", else just the class name. Used to make input devices
+/// recognizable in logs.
+pub fn interfaceName(class: u8, subclass: u8, protocol: u8) []const u8 {
+    if (@as(Class, @enumFromInt(class)) == .hid and subclass == @intFromEnum(hid.SubClass.boot)) {
+        return switch (@as(hid.Protocol, @enumFromInt(protocol))) {
+            .keyboard => "HID boot keyboard",
+            .mouse => "HID boot mouse",
+            else => "HID",
+        };
+    }
+    return className(class);
+}
+
 // Subclass and protocol codes qualified by Class.hub. Hubs have no subclass codes; the
 // protocol distinguishes the hub's transaction-translator arrangement.
 pub const hub = struct {

system/drivers/usb-xhci-bus/usb-xhci-bus.zig

@@ -230,8 +230,9 @@ fn bringUpPort(manager: runtime.ipc.Handle, engine: *library.Controller, port: u
         std.log.info("port {d} enumeration failed", .{port});
         return;
     }
-    std.log.info("port {d} device vendor 0x{x:0>4} product 0x{x:0>4}, {d} interface(s)", .{
+    std.log.info("port {d} device: {s} vendor 0x{x:0>4} product 0x{x:0>4}, {d} interface(s)", .{
         port,
+        usb_ids.className(usb_device.device_descriptor.device_class),
         usb_device.device_descriptor.vendor_id,
         usb_device.device_descriptor.product_id,
         usb_device.interface_count,
@@ -279,8 +280,9 @@ fn bringUpBehindHub(manager: runtime.ipc.Handle, engine: *library.Controller, hu
         std.log.info("hub slot {d} port {d}: enumeration failed", .{ hub.slot_id, port });
         return;
     }
-    std.log.info("hub slot {d} port {d} device vendor 0x{x:0>4} product 0x{x:0>4}, {d} interface(s)", .{
+    std.log.info("hub slot {d} port {d} device: {s} vendor 0x{x:0>4} product 0x{x:0>4}, {d} interface(s)", .{
         hub.slot_id, port,
+        usb_ids.className(usb_device.device_descriptor.device_class),
         usb_device.device_descriptor.vendor_id,
         usb_device.device_descriptor.product_id,
         usb_device.interface_count,
@@ -387,9 +389,10 @@ fn reportInterface(manager: runtime.ipc.Handle, port: u32, interface: library.In
         std.log.info("child report for port {d} interface {d} failed", .{ port, interface.number });
         return null;
     };
-    std.log.info("port {d} interface {d} class {d}/{d}/{d} registered as device {d}", .{
+    std.log.info("port {d} interface {d}: {s} ({d}/{d}/{d}) registered as device {d}", .{
         port,
         interface.number,
+        usb_ids.interfaceName(interface.class, interface.subclass, interface.protocol),
         interface.class,
         interface.subclass,
         interface.protocol,

test/qemu_test.py

@@ -494,7 +494,7 @@ CASES = [
      # B4a: the hub powers its ports. B4b: the keyboard behind it enumerates
      # (route string + TT) and binds usb-hid-keyboard.
      "expect": r"(?s)(?=.*hub slot \d+: \d+ downstream ports powered)"
-               r"(?=.*hub slot \d+ port \d+ device vendor 0x0627)"
+               r"(?=.*hub slot \d+ port \d+ device:.*vendor 0x0627)"
                r"(?=.*usb-hid-keyboard: ok \(device 3)",
      "fail":   r"DANOS-TEST-RESULT: FAIL"},
     # USB mass storage end to end: the boot usb-storage device (the FAT32 image,
@@ -676,7 +676,7 @@ CASES = [
                     "-device", "usb-hub,bus=xhci2.0,port=1",
                     "-device", "usb-hub,bus=xhci2.0,port=1.1",
                     "-device", "usb-kbd,bus=xhci2.0,port=1.1.1"],
-     "expect": r"(?s)(?=.*hub slot \d+ port \d+ device vendor 0x0409)"
+     "expect": r"(?s)(?=.*hub slot \d+ port \d+ device:.*vendor 0x0409)"
                r"(?=.*usb-hid-keyboard: ok \(device 3)",
      "fail":   r"DANOS-TEST-RESULT: FAIL"},
     # Hub-downstream disconnect (B4c): device_del the keyboard behind the hub;