[PATCH dev-5.4 01/14] dt-bindings: Add PECI subsystem document
Jae Hyun Yoo
jae.hyun.yoo at linux.intel.com
Wed Dec 18 12:27:55 AEDT 2019
This commit adds PECI subsystem document.
Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo at linux.intel.com>
---
Changes since v11:
- None
Changes since v10:
- Changed documents format to DT schema format so I dropped all review tags.
Please review it again.
.../devicetree/bindings/peci/peci-bus.yaml | 129 ++++++++++++++++++
.../devicetree/bindings/peci/peci-client.yaml | 54 ++++++++
2 files changed, 183 insertions(+)
create mode 100644 Documentation/devicetree/bindings/peci/peci-bus.yaml
create mode 100644 Documentation/devicetree/bindings/peci/peci-client.yaml
diff --git a/Documentation/devicetree/bindings/peci/peci-bus.yaml b/Documentation/devicetree/bindings/peci/peci-bus.yaml
new file mode 100644
index 000000000000..b085e67089cf
--- /dev/null
+++ b/Documentation/devicetree/bindings/peci/peci-bus.yaml
@@ -0,0 +1,129 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/peci/peci-bus.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic Device Tree Bindings for PECI bus
+
+maintainers:
+ - Jae Hyun Yoo <jae.hyun.yoo at linux.intel.com>
+
+description: |
+ PECI (Platform Environment Control Interface) is a one-wire bus interface that
+ provides a communication channel from Intel processors and chipset components
+ to external monitoring or control devices. PECI is designed to support the
+ following sideband functions:
+
+ * Processor and DRAM thermal management
+ - Processor fan speed control is managed by comparing Digital Thermal
+ Sensor (DTS) thermal readings acquired via PECI against the
+ processor-specific fan speed control reference point, or TCONTROL. Both
+ TCONTROL and DTS thermal readings are accessible via the processor PECI
+ client. These variables are referenced to a common temperature, the TCC
+ activation point, and are both defined as negative offsets from that
+ reference.
+ - PECI based access to the processor package configuration space provides
+ a means for Baseboard Management Controllers (BMC) or other platform
+ management devices to actively manage the processor and memory power
+ and thermal features.
+
+ * Platform Manageability
+ - Platform manageability functions including thermal, power, and error
+ monitoring. Note that platform 'power' management includes monitoring
+ and control for both the processor and DRAM subsystem to assist with
+ data center power limiting.
+ - PECI allows read access to certain error registers in the processor MSR
+ space and status monitoring registers in the PCI configuration space
+ within the processor and downstream devices.
+ - PECI permits writes to certain registers in the processor PCI
+ configuration space.
+
+ * Processor Interface Tuning and Diagnostics
+ - Processor interface tuning and diagnostics capabilities
+ (Intel Interconnect BIST). The processors Intel Interconnect Built In
+ Self Test (Intel IBIST) allows for infield diagnostic capabilities in
+ the Intel UPI and memory controller interfaces. PECI provides a port to
+ execute these diagnostics via its PCI Configuration read and write
+ capabilities.
+
+ * Failure Analysis
+ - Output the state of the processor after a failure for analysis via
+ Crashdump.
+
+ PECI uses a single wire for self-clocking and data transfer. The bus
+ requires no additional control lines. The physical layer is a self-clocked
+ one-wire bus that begins each bit with a driven, rising edge from an idle
+ level near zero volts. The duration of the signal driven high depends on
+ whether the bit value is a logic '0' or logic '1'. PECI also includes
+ variable data transfer rate established with every message. In this way, it
+ is highly flexible even though underlying logic is simple.
+
+ The interface design was optimized for interfacing between an Intel
+ processor and chipset components in both single processor and multiple
+ processor environments. The single wire interface provides low board
+ routing overhead for the multiple load connections in the congested routing
+ area near the processor and chipset components. Bus speed, error checking,
+ and low protocol overhead provides adequate link bandwidth and reliability
+ to transfer critical device operating conditions and configuration
+ information.
+
+ PECI subsystem provides single or multiple bus nodes support so each bus can
+ have one adapter node and multiple device specific client nodes that can be
+ attached to the PECI bus so each processor client's features can be supported
+ by the client node through an adapter connection in the bus.
+
+properties:
+ compatible:
+ const: simple-bus
+
+ "#address-cells":
+ # Required to define bus device control resource address.
+ const: 1
+
+ "#size-cells":
+ # Required to define bus device control resource address.
+ const: 1
+
+ ranges: true
+
+required:
+ - compatible
+ - "#address-cells"
+ - "#size-cells"
+ - ranges
+
+examples:
+ - |
+ #include <dt-bindings/interrupt-controller/arm-gic.h>
+ #include <dt-bindings/clock/ast2600-clock.h>
+ peci: bus at 1e78b000 {
+ compatible = "simple-bus";
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges = <0x0 0x1e78b000 0x200>;
+
+ peci0: peci-bus at 0 {
+ compatible = "aspeed,ast2600-peci";
+ reg = <0x0 0x100>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ interrupts = <GIC_SPI 38 IRQ_TYPE_LEVEL_HIGH>;
+ clocks = <&syscon ASPEED_CLK_GATE_REF0CLK>;
+ resets = <&syscon ASPEED_RESET_PECI>;
+ clock-frequency = <24000000>;
+ };
+
+ // Just an example. ast2600 doesn't have a second PECI module actually.
+ peci1: peci-bus at 100 {
+ compatible = "aspeed,ast2600-peci";
+ reg = <0x100 0x100>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ interrupts = <GIC_SPI 39 IRQ_TYPE_LEVEL_HIGH>;
+ clocks = <&syscon ASPEED_CLK_GATE_REF0CLK>;
+ resets = <&syscon ASPEED_RESET_PECI>;
+ clock-frequency = <24000000>;
+ };
+ };
+...
diff --git a/Documentation/devicetree/bindings/peci/peci-client.yaml b/Documentation/devicetree/bindings/peci/peci-client.yaml
new file mode 100644
index 000000000000..fc7c4110e929
--- /dev/null
+++ b/Documentation/devicetree/bindings/peci/peci-client.yaml
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/peci/peci-client.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic Device Tree Bindings for PECI clients
+
+maintainers:
+ - Jae Hyun Yoo <jae.hyun.yoo at linux.intel.com>
+
+properties:
+ compatible:
+ enum:
+ - intel,peci-client
+
+ reg:
+ description: |
+ Address of a client CPU. According to the PECI specification, client
+ addresses start from 0x30.
+ maxItems: 1
+
+examples:
+ - |
+ #include <dt-bindings/interrupt-controller/arm-gic.h>
+ #include <dt-bindings/clock/ast2600-clock.h>
+ peci: bus at 1e78b000 {
+ compatible = "simple-bus";
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges = <0x0 0x1e78b000 0x60>;
+
+ peci0: peci-bus at 0 {
+ compatible = "aspeed,ast2600-peci";
+ reg = <0x0 0x100>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ interrupts = <GIC_SPI 38 IRQ_TYPE_LEVEL_HIGH>;
+ clocks = <&syscon ASPEED_CLK_GATE_REF0CLK>;
+ resets = <&syscon ASPEED_RESET_PECI>;
+ clock-frequency = <24000000>;
+
+ peci-client at 30 {
+ compatible = "intel,peci-client";
+ reg = <0x30>;
+ };
+
+ peci-client at 31 {
+ compatible = "intel,peci-client";
+ reg = <0x31>;
+ };
+ };
+ };
+...
--
2.17.1
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