unable to use macbook pro retina webcam

cheese, google hangouts plugin, etc can't find a camera.
according to http://mactaris.blogspot.co.uk/2013/07/webcam-settings-20-will-support.html , the camera is no longer a UVC device, but on the PCIe bus instead.

lspci -vvv shows:
04:00.0 Multimedia controller: Broadcom Corporation Device 1570
 Subsystem: Broadcom Corporation Device 1570
 Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
 Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
 Latency: 0, Cache Line Size: 256 bytes
 Interrupt: pin A routed to IRQ 0
 Region 0: Memory at c1d00000 (64-bit, non-prefetchable) [size=64K]
 Region 2: Memory at a0000000 (64-bit, prefetchable) [size=256M]
 Region 4: Memory at c1c00000 (64-bit, non-prefetchable) [size=1M]
 Capabilities: [48] Power Management version 3
  Flags: PMEClk- DSI- D1+ D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold-)
  Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=2 PME-
 Capabilities: [58] MSI: Enable- Count=1/1 Maskable- 64bit+
  Address: 0000000000000000 Data: 0000
 Capabilities: [68] Vendor Specific Information: Len=44 <?>
 Capabilities: [ac] Express (v2) Endpoint, MSI 00
  DevCap: MaxPayload 512 bytes, PhantFunc 0, Latency L0s <4us, L1 unlimited
   ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
  DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
   RlxdOrd+ ExtTag- PhantFunc- AuxPwr+ NoSnoop+
   MaxPayload 128 bytes, MaxReadReq 512 bytes
  DevSta: CorrErr+ UncorrErr- FatalErr- UnsuppReq+ AuxPwr- TransPend-
  LnkCap: Port #0, Speed 5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <2us, L1 <32us
   ClockPM+ Surprise- LLActRep- BwNot-
  LnkCtl: ASPM L1 Enabled; RCB 64 bytes Disabled- CommClk+
   ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
  LnkSta: Speed 5GT/s, Width x1, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
  DevCap2: Completion Timeout: Range ABCD, TimeoutDis+, LTR+, OBFF Via WAKE#
  DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR+, OBFF Disabled
  LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
    Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
    Compliance De-emphasis: -6dB
  LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete-, EqualizationPhase1-
    EqualizationPhase2-, EqualizationPhase3-, LinkEqualizationRequest-
 Capabilities: [100 v1] Advanced Error Reporting
  UESta: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
  UEMsk: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
  UESvrt: DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
  CESta: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
  CEMsk: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
  AERCap: First Error Pointer: 00, GenCap+ CGenEn- ChkCap+ ChkEn-
 Capabilities: [13c v1] Device Serial Number 00-00-00-ff-ff-00-00-00
 Capabilities: [150 v1] Power Budgeting <?>
 Capabilities: [160 v1] Virtual Channel
  Caps: LPEVC=0 RefClk=100ns PATEntryBits=1
  Arb: Fixed- WRR32- WRR64- WRR128-
  Ctrl: ArbSelect=Fixed
  Status: InProgress-
  VC0: Caps: PATOffset=00 MaxTimeSlots=1 RejSnoopTrans-
   Arb: Fixed- WRR32- WRR64- WRR128- TWRR128- WRR256-
   Ctrl: Enable+ ID=0 ArbSelect=Fixed TC/VC=ff
   Status: NegoPending- InProgress-
 Capabilities: [1b0 v1] Latency Tolerance Reporting
  Max snoop latency: 71680ns
  Max no snoop latency: 71680ns
 Capabilities: [220 v1] #15

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-15-generic 3.13.0-15.35
ProcVersionSignature: Ubuntu 3.13.0-15.35-generic 3.13.5
Uname: Linux 3.13.0-15-generic x86_64
NonfreeKernelModules: nvidia wl
ApportVersion: 2.13.2-0ubuntu5
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: jbarnett 2348 F.... pulseaudio
 /dev/snd/controlC0: jbarnett 2348 F.... pulseaudio
 /dev/snd/pcmC0D0c: jbarnett 2348 F...m pulseaudio
 /dev/snd/pcmC0D0p: jbarnett 2348 F...m pulseaudio
CurrentDesktop: GNOME
Date: Tue Mar 4 16:25:48 2014
HibernationDevice: RESUME=UUID=948280a0-a059-468d-8484-f0d317f46e6d
InstallationDate: Installed on 2014-02-24 (8 days ago)
InstallationMedia: Ubuntu-GNOME 14.04 "Trusty Tahr" - Alpha amd64 (20140218)
MachineType: Apple Inc. MacBookPro11,3
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB: 0 EFI VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-15-generic.efi.signed root=UUID=135fd833-3282-4f3b-8802-0a27ec2765b9 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-15-generic N/A
 linux-backports-modules-3.13.0-15-generic N/A
 linux-firmware 1.125
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/18/2013
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MBP112.88Z.0138.B02.1310181745
dmi.board.asset.tag: Base Board Asset Tag#
dmi.board.name: Mac-2BD1B31983FE1663
dmi.board.vendor: Apple Inc.
dmi.board.version: MacBookPro11,3
dmi.chassis.type: 10
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-2BD1B31983FE1663
dmi.modalias: dmi:bvnAppleInc.:bvrMBP112.88Z.0138.B02.1310181745:bd10/18/2013:svnAppleInc.:pnMacBookPro11,3:pvr1.0:rvnAppleInc.:rnMac-2BD1B31983FE1663:rvrMacBookPro11,3:cvnAppleInc.:ct10:cvrMac-2BD1B31983FE1663:
dmi.product.name: MacBookPro11,3
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.