From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Date: Sat, 6 Mar 2021 13:30:11 -0700 Subject: [PATCH v4 1/4] dt-bindings: i2c: aspeed: add transfer mode support In-Reply-To: <20210224191720.7724-2-jae.hyun.yoo@linux.intel.com> References: <20210224191720.7724-1-jae.hyun.yoo@linux.intel.com> <20210224191720.7724-2-jae.hyun.yoo@linux.intel.com> Message-ID: <20210306203011.GA1152769@robh.at.kernel.org> List-Id: To: linux-aspeed@lists.ozlabs.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 > Reviewed-by: Brendan Higgins > --- > 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 at 0 { > - #interrupt-cells = <1>; > - compatible = "aspeed,ast2400-i2c-ic"; > + i2c_gr: i2c-global-regs at 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 at 0 { > + #interrupt-cells = <1>; > + compatible = "aspeed,ast2500-i2c-ic"; > + reg = <0x0 0x4>; > + interrupts = <12>; > + interrupt-controller; > + }; > }; > > i2c0: i2c-bus at 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 >