This commit adds a dt-bindings document for Aspeed PECI.
Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@xxxxxxxxxxxxxxx>
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.../devicetree/bindings/misc/aspeed-peci.txt | 55 ++++++++++++++++++++++
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create mode 100644 Documentation/devicetree/bindings/misc/aspeed-peci.txt
diff --git a/Documentation/devicetree/bindings/misc/aspeed-peci.txt b/Documentation/devicetree/bindings/misc/aspeed-peci.txt
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+* ASPEED PECI (Platform Environment Control Interface) misc driver.
+
+Hardware Interfaces:
+- This driver implements support for the ASPEED AST2400/2500 PECI which has the
+ following features:
+ - Directly connected to APB bus
+ - Intel PECI 3.1 compliant (PECI 3.0 for AST2400)
+ - Maximum packet length is 256 bytes (Baseline transmission unit)
+ - Support up to 8 CPUs and 2 domains per CPU
+ - Integrate PECI compliant I/O buffers, can connect to PECI bus directly
+ - Transmit buffer 32 bytes and receive buffer 32 bytes
+
+Required properties:
+- compatible: "aspeed,ast2400-peci" or "aspeed,ast2500-peci"
+ - aspeed,ast2400-peci: Aspeed AST2400 family PECI control interface
+ - aspeed,ast2500-peci: Aspeed AST2500 family PECI control interface
+- reg: Should contain PECI registers location and length
+- interrupts: Should contain PECI interrupt
+- clocks: Should contain clock source. = <&clk_clkin>;
+- clock_frequency: Should contain the operation frequency of PECI controller.
+ 187500 ~ 24000000
+
+Optional properties:
+- msg-timing-nego: Message timing negotiation period.
+ This value will determine the period of message timing negotiation to be
+ issued by PECI controller. The unit of the programmed value is four
+ times of PECI clock period.
+ 0 ~ 255 (default: 1)
+- addr-timing-nego: Address timing negotiation period.
+ This value will determine the period of address timing negotiation to be
+ issued by PECI controller. The unit of the programmed value is four
+ times of PECI clock period.
+ 0 ~ 255 (default: 1)
+- rd-sampling-point: Read sampling point selection.
+ The whole period of a bit time will be divided into 16 time frames.
+ This value will determine which time frame this controller will sample
+ PECI signal for data read back. Usually in the middle of a bit time is
+ the best.
+ 0 ~ 15 (default: 8)
+- cmd_timeout_ms: Command timeout in units of ms
+ 1 ~ 60000 (default: 1000)
+
+Example:
+ peci: peci@1e78b000 {
+ compatible = "aspeed,ast2500-peci";
+ reg = <0x1e78b000 0x60>;
+ interrupt-controller;
+ interrupts = <15>;
+ clocks = <&clk_clkin>;
+ clock-frequency = <24000000>;
+ msg-timing-nego = <1>;
+ addr-timing-nego = <1>;
+ rd-sampling-point = <8>;
+ cmd-timeout-ms = <1000>;
+ };
--
2.7.4
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