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| author | Jae Hyun Yoo <jae.hyun.yoo@intel.com> | 2019-06-18 18:47:50 +0300 |
|---|---|---|
| committer | Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com> | 2021-11-05 10:22:08 +0300 |
| commit | 9ae84a5a6a44cf5625c088fa99876372c613ee63 (patch) | |
| tree | a7849b4bc5f60400067c5cf4763bdc0a99a26886 /Documentation/devicetree | |
| parent | 36b8d0f5c30ff7dea194ec18d32c5f07620202d6 (diff) | |
| download | linux-9ae84a5a6a44cf5625c088fa99876372c613ee63.tar.xz | |
i2c: aspeed: add DMA mode transfer support
This commit adds DMA mode transfer support.
Only AST2500 supports DMA mode under some limitations:
I2C is sharing the DMA H/W with UHCI host controller and MCTP
controller. Since those controllers operate with DMA mode only, I2C
has to use buffer mode or byte mode instead if one of those
controllers is enabled. Also make sure that if SD/eMMC or Port80
snoop uses DMA mode instead of PIO or FIFO respectively, I2C can't
use DMA mode.
Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@intel.com>
Diffstat (limited to 'Documentation/devicetree')
| -rw-r--r-- | Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml b/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml index 30f9b9bde47a..910182cc971a 100644 --- a/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml +++ b/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml @@ -58,6 +58,19 @@ properties: description: Number of retries for master transfer + aspeed,dma-buf-size: + $ref: /schemas/types.yaml#/definitions/uint32 + description: + size of DMA buffer (from 2 to 4095 in case of AST2500) + Only AST2500/2600 support DMA mode. + Limitations on AST2500 - I2C is sharing the DMA H/W with UHCI host + controller and MCTP controller. Since those controllers operate with DMA + mode only, I2C has to use buffer mode or byte mode instead if one of + those controllers is enabled. Also make sure that if SD/eMMC or Port80 + snoop uses DMA mode instead of PIO or FIFO respectively, I2C can't use + DMA mode. IF both DMA and buffer modes are enabled, DMA mode will be + selected. + required: - reg - compatible |