[V2 0/3] spi: Add DMA mode support to spi-qcom-qspi

[Vijaya Krishna Nivarthi]

There are large number of QSPI irqs that fire during boot/init and later
on every suspend/resume.
This could be made faster by doing DMA instead of PIO.
Below is comparison for number of interrupts raised in 2 acenarios...
Boot up and stabilise
Suspend/Resume

Sequence   PIO    DMA
=======================
Boot-up    69088  19284
S/R        5066   3430

Though we have not made measurements for speed, power we expect
the performance to be better with DMA mode and no regressions were
encountered in testing.

Vijaya Krishna Nivarthi (3):
  spi: dt-bindings: qcom,spi-qcom-qspi: Add iommus binding for qspi
  arm64: dts: qcom: sc7280: Add stream-id of qspi to iommus
  spi: spi-qcom-qspi: Add DMA mode support
---
v1 -> v2:
- Added documentation file to the series
- Made changes to driver based on HPG re-review
---
 .../bindings/spi/qcom,spi-qcom-qspi.yaml           |   3 +
 arch/arm64/boot/dts/qcom/sc7280.dtsi               |   1 +
 drivers/spi/spi-qcom-qspi.c                        | 434 +++++++++++++++++++--
 3 files changed, 407 insertions(+), 31 deletions(-)

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