On Wed, Feb 24, 2021 at 11:17:17AM -0800, Jae Hyun Yoo wrote:
> Append bindings to support transfer mode.
>
> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@xxxxxxxxxxxxxxx>
> Reviewed-by: Brendan Higgins <brendanhiggins@xxxxxxxxxx>
> ---
> Changes since v3:
> - None
>
> Changes since v2:
> - Moved SRAM resources back to default dtsi and added mode selection
> property.
>
> Changes since v1:
> - Removed buffer reg settings from default device tree and added the settings
> into here to show the predefined buffer range per each bus.
>
> .../devicetree/bindings/i2c/i2c-aspeed.txt | 37 +++++++++++++++----
> 1 file changed, 30 insertions(+), 7 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-aspeed.txt b/Documentation/devicetree/bindings/i2c/i2c-aspeed.txt
> index b47f6ccb196a..242343177324 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-aspeed.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-aspeed.txt
> @@ -17,6 +17,20 @@ Optional Properties:
> - bus-frequency : frequency of the bus clock in Hz defaults to 100 kHz when not
> specified
> - multi-master : states that there is another master active on this bus.
> +- aspeed,i2c-xfer-mode : should be "byte", "buf" or "dma" to select transfer
> + mode defaults to "byte" mode when not specified.
> +
> + I2C DMA mode on AST2500 has these restrictions:
> + - If one of these controllers is enabled
> + * UHCI host controller
> + * MCTP controller
> + I2C has to use buffer mode or byte mode instead
> + since these controllers run only in DMA mode and
> + I2C is sharing the same DMA H/W with them.
> + - If one of these controllers uses DMA mode, I2C
> + can't use DMA mode
> + * SD/eMMC
> + * Port80 snoop
How does one decide between byte or buf mode?
>
> Example:
>
> @@ -26,20 +40,29 @@ i2c {
> #size-cells = <1>;
> ranges = <0 0x1e78a000 0x1000>;
>
> - i2c_ic: interrupt-controller@0 {
> - #interrupt-cells = <1>;
> - compatible = "aspeed,ast2400-i2c-ic";
> + i2c_gr: i2c-global-regs@0 {
> + compatible = "aspeed,ast2500-i2c-gr", "syscon";
> reg = <0x0 0x40>;
> - interrupts = <12>;
> - interrupt-controller;
> +
> + #address-cells = <1>;
> + #size-cells = <1>;
> + ranges = <0x0 0x0 0x40>;
> +
> + i2c_ic: interrupt-controller@0 {
> + #interrupt-cells = <1>;
> + compatible = "aspeed,ast2500-i2c-ic";
> + reg = <0x0 0x4>;
> + interrupts = <12>;
> + interrupt-controller;
> + };
> };
>
> i2c0: i2c-bus@40 {
> #address-cells = <1>;
> #size-cells = <0>;
> #interrupt-cells = <1>;
> - reg = <0x40 0x40>;
> - compatible = "aspeed,ast2400-i2c-bus";
> + reg = <0x40 0x40>, <0x200 0x10>;
> + compatible = "aspeed,ast2500-i2c-bus";
The example changes are all unrelated to adding the new property. Should
be a separate patch or just dropped.
> clocks = <&syscon ASPEED_CLK_APB>;
> resets = <&syscon ASPEED_RESET_I2C>;
> bus-frequency = <100000>;
> --
> 2.17.1
>
