[PATCH v2 0/3] Add Loongson-2K0300 APB DMA mux support

[Binbin Zhou <zhoubinbin@loongson.cn>]

Hi all:

Loongson-2K0300 integrates a CMC DMA controller with 8 physical
channels. Peripheral DMA requests are not hard-wired to these channels;
they are routed through the CHIP_CTRL13/14/15 DMA_MAP fields.

This series adds support for that DMA request router.

Patch 1 adds the DT binding constants for the peripheral request IDs.
Patch 2 adds the DT binding documentation for the DMA mux.
Patch 3 adds the driver, Kconfig symbol and Makefile entry.

The driver registers with of_dma_router_register(). In the route
allocation callback it validates the <request> <channel> <flags>
specifier, programs the SoC-specific route register, and forwards
<channel> <flags> to the parent CMC DMA controller.

Thanks.
Binbin.

=========
V2:
Patch(1/3):
 - Drop LS2K0300_DMA_REQ_MAX as it is not part of the ABI;
Patch(2/3):
 - More detailed description of `dma-cells`;
 - Add the `dma_requests` constraint
Patch(3/3):
 - Drop loongson2_dmamux_map->shift;
 - Move of_parse_phandle() into loongson2_dmamux_route_allocate() avoid
   UAF;
 - Drop loongson2_dmamux->dma_np;
 - Check dma_requests;
 - Add devm_add_action_or_reset() instead of .remove();
 - Replace `metux()` with `spinlock()`, which has lower overhead;
 - Add loongson2_dmamux_route_free().

Link to V1:
https://lore.kernel.org/all/cover.1790068409.git.zhoubinbin@loongson.cn/

Binbin Zhou (3):
  dt-bindings: dma: loongson: Add Loongson-2 DMA mux request IDs
  dt-bindings: dma: loongson: Add Loongson-2K0300 DMA mux support
  dmaengine: loongson: Add Loongson-2K0300 APB DMA mux driver

 .../dma/loongson,ls2k0300-dmamux.yaml         |  72 ++++
 MAINTAINERS                                   |   3 +
 drivers/dma/loongson/Makefile                 |   1 +
 drivers/dma/loongson/loongson2-apb-dmamux.c   | 398 ++++++++++++++++++
 .../dt-bindings/dma/loongson,ls2k-dmamux.h    |  53 +++
 5 files changed, 527 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/dma/loongson,ls2k0300-dmamux.yaml
 create mode 100644 drivers/dma/loongson/loongson2-apb-dmamux.c
 create mode 100644 include/dt-bindings/dma/loongson,ls2k-dmamux.h


base-commit: 1d8ae2003de08f61095e4e928b1b8cce6c23cabd
-- 
2.52.0