[PATCH v5] add support for Mediatek Command-Queue DMA controller on MT6765 SoC

[shun-chih.yu]

This patchset introduces support for MediaTek Command-Queue DMA controller.

MediaTek Command-Queue DMA controller (CQDMA) on MT6765 SoC is dedicated to memory-to-memory transfer through queue-based descriptor management.

There are only 3 physical channels inside CQDMA, while the driver is extended to support 32 virtual channels for multiple dma users to issue dma requests onto the CQDMA simultaneously.

dmatest result:
dmatest: dma0chan0-copy2: summary 5000 tests, 0 failures 3500 iops 28037 KB/s (0)
dmatest: dma0chan0-copy4: summary 5000 tests, 0 failures 3494 iops 27612 KB/s (0)
dmatest: dma0chan0-copy1: summary 5000 tests, 0 failures 3491 iops 27749 KB/s (0)
dmatest: dma0chan0-copy7: summary 5000 tests, 0 failures 3673 iops 29092 KB/s (0)
dmatest: dma0chan0-copy6: summary 5000 tests, 0 failures 3763 iops 30237 KB/s (0)
dmatest: dma0chan0-copy0: summary 5000 tests, 0 failures 3730 iops 30131 KB/s (0)
dmatest: dma0chan0-copy3: summary 5000 tests, 0 failures 3717 iops 29569 KB/s (0)
dmatest: dma0chan0-copy5: summary 5000 tests, 0 failures 3699 iops 29302 KB/s (0)

Changes since v4:
- remove redundant queue structure in mtk_cqdma_pchan
- remove redundant completion management
- fix wrong residue assignment in mtk_cqdma_tx_status
- fix typos

Changes since v3:
- simplify the ISR and management on descriptors by removing tasklet and ASYNC_TX_ENABLE_CHANNEL_SWITCH
- remove useless field in mtk_cqdma_vdesc structure
- change dev_info to dev_dbg
- fix typos

Changes since v2:
- fix build warning for kernel with DMA address in 32-bit

Changes since v1:
- remove unused macros, typos
- leverage ASYNC_TX_ENABLE_CHANNEL_SWITCH to maintain DMA descriptor list

Shun-Chih Yu (2):
  dt-bindings: dmaengine: Add MediaTek Command-Queue DMA controller
    bindings
  dmaengine: mediatek: Add MediaTek Command-Queue DMA controller for
    MT6765 SoC
 
 .../devicetree/bindings/dma/mtk-cqdma.txt          |   31 +
 drivers/dma/mediatek/Kconfig                       |   12 +
 drivers/dma/mediatek/Makefile                      |    1 +
 drivers/dma/mediatek/mtk-cqdma.c                   |  748 ++++++++++++++++++++
 4 files changed, 792 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/dma/mtk-cqdma.txt
 create mode 100644 drivers/dma/mediatek/mtk-cqdma.c