[Feature] Low Power I/O-SPI enumerates and provides legacy functionality

Per discussion between Canonical and Intel, retarget to 15.10.

Merged into maintainer's tree for next:
https://git.kernel.org/cgit/linux/kernel/git/broonie/spi.git/commit/?h=topic/pxa2xx&id=34cadd9c1bcbd5ad5a1f379b013526a8046d4aed

Hi Xiong,

The link to the commit in comment #2 is not longer valid unfortunately. Do you know if this made it upstream for 4.2 or will it be in 4.3? Thanks.

This feature depends on LP1460908. LP1460908 will be in 4.3 kernel.

Beside back port patches in LP1460908, please back port the following patches also from 4.3 kernel

757fe8d spi: spi-pxa2xx: Remove unused legacy null dma buffer and allocation for
94e5c23 spi: pxa2xx: Add terminating entry for pxa2xx_spi_pci_compound_match
f47da24 spi: spi-pxa2xx: Remove unused legacy PXA DMA API channel numbers
34cadd9 spi: pxa2xx: Add support for Intel Sunrisepoint

This bug was fixed in the package linux - 4.2.0-10.11

---------------
linux (4.2.0-10.11) wily; urgency=low

  [ Andy Whitcroft ]

  * Release Tracking Bug
    - LP: #1495208
  * No change rebuild to avoid issues with leading zero bytes on
    internal module signing key. (see launchpad bug 1494943)

  [ Ming Lei ]

  * [Config] SERIAL_8250_DW=y for arm64

  [ Upstream Kernel Changes ]

  * drm/i915: Move WaBarrierPerformanceFixDisable:skl to skl code from chv
    code
    - LP: #1484486
  * drm/i915/gen8: Add infrastructure to initialize WA batch buffers
    - LP: #1484486
  * drm/i915/gen8: Re-order init pipe_control in lrc mode
    - LP: #1484486
  * drm/i915/gen8: Add WaDisableCtxRestoreArbitration workaround
    - LP: #1484486
  * drm/i915/gen8: Add WaFlushCoherentL3CacheLinesAtContextSwitch
    workaround
    - LP: #1484486
  * drm/i915: Bail out early if WA batch is not available for given Gen
    - LP: #1484486
  * drm/i915/gen8: Add WaClearSlmSpaceAtContextSwitch workaround
    - LP: #1484486
  * drm/i915: Update WaFlushCoherentL3CacheLinesAtContextSwitch
    - LP: #1484486
  * drm/i915/gen9: Implement WaDisableKillLogic for gen 9
    - LP: #1484486
  * drm/i915: Enable WA batch buffers for Gen9
    - LP: #1484486
  * drm/i915/gen9: Add WaDisableCtxRestoreArbitration workaround
    - LP: #1484486
  * drm/i915: Update wa_ctx_emit() macro as per kernel coding guidelines
    - LP: #1484486
  * drm/i915/gen9: Add WaFlushCoherentL3CacheLinesAtContextSwitch
    workaround
    - LP: #1484486
  * drm/i915/gen9: Add
    WaSetDisablePixMaskCammingAndRhwoInCommonSliceChicken
    - LP: #1484486
  * drm/i915:skl: Add WaEnableGapsTsvCreditFix
    - LP: #1484486
  * drm/i915/skl: revert duplicated WaBarrierPerformanceFixDisable:skl
    - LP: #1484486
  * drm/i915/skl: Don't expose the top most plane on gen9 display
    - LP: #1484486
  * drm/i915/skl WaDisableSbeCacheDispatchPortSharing
    - LP: #1484486
  * drm/i915/skl: WaIgnoreDDIAStrap is forever, always init DDI A
    - LP: #1484486
  * drm/i915: reduce indent in i9xx_hpd_irq_handler
    - LP: #1484531
  * drm/i915: reduce duplicate conditions in i9xx_hpd_irq_handler
    - LP: #1484531
  * drm/i915: reduce indent in intel_hpd_irq_handler
    - LP: #1484531
  * drm/i915: group all hotplug related fields into a new struct in
    dev_priv
    - LP: #1484531
  * drm/i915: add for_each_hpd_pin to iterate over hotplug pins
    - LP: #1484531
  * drm/i915: simplify conditions for skipping the 2nd hpd loop iterations
    - LP: #1484531
  * drm/i915: put back the indent in intel_hpd_irq_handler
    - LP: #1484531
  * drm/i915: merge the two hpd loops in intel_hpd_irq_handler to one
    - LP: #1484531
  * drm/i915: simplify condition for digital port
    - LP: #1484531
  * drm/i915: abstract away platform specific parts from hpd handling
    - LP: #1484531
  * drm/i915: Handle HPD when it has actually occurred
    - LP: #1484531
  * drm/i915: Set power domain for DDI-E
    - LP: #1484531
  * drm/i915: Set alternate aux for DDI-E
    - LP: #1484531
  * drm/i915/skl: enable DDI-E hotplug
    - LP: #1484531
  * drm/i915/bxt: fix DDI PHY vswing scale value setting
    - LP: #1494163
  * drm/i915/skl: Buf...