[PATCH linux-next v6 00/13] PECI device driver introduction

[PATCH linux-next v6 00/13] PECI device driver introduction

[Jae Hyun Yoo]

Introduction of the Platform Environment Control Interface (PECI) bus
device driver. PECI 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.

This implementation provides the basic framework to add PECI extensions to
the Linux bus and device models. A hardware specific 'Adapter' driver can
be attached to the PECI bus to provide sideband functions described above.
It is also possible to access all devices on an adapter from userspace
through the /dev interface. A device specific 'Client' driver also can be
attached to the PECI bus so each processor client's features can be
supported by the 'Client' driver through an adapter connection in the bus.
This patch set includes Aspeed 24xx/25xx PECI driver and PECI
cputemp/dimmtemp drivers as the first implementation for both adapter and
client drivers on the PECI bus framework.

Please review.

Thanks,

-Jae

Changes since v5:
* Added more detailed descriptions for PECI client MFD documents.
* Changed PECI client MFD souce file names.
* Fixed DT example of PECI client MFD.
* Removed unnecessary debug printings.
* Moved the asm/intel-family.h inclusion place.

Changes since v4:
* Fixed an incorrect endianness handling in peci-aspeed.
* Added a comment to explain about the asm/intel-family.h inclusion.
* Added an MFD module to support multi-function PECI client devices.

Changes since v3:
* Made code more simple and compact.
* Removed unused header file inclusion.
* Fixed incorrect error return values and messages.
* Removed DTS margin temperature from the peci-cputemp.
* Made some magic numbers use defines.
* Moved peci_get_cpu_id() into peci-core as a common function.
* Replaced the cancel_delayed_work() call with a cancel_delayed_work_sync().
* Replaced AST and Aspeed uses with ASPEED.
* Simplified peci command timeout checking logic using
  regmap_read_poll_timeout().
* Simplified endian swap codes using endian handling macros.
* Dropped regmap read/write error checking except for the first access.
* Added a PECI reset setting in the device tree node.
* Removed unnecessary sleep from the probe context.
* Removed IRQF_SHARED flag from irq request code in the ASPEED PECI driver.
* Fixed typos in documents.
* Combined peci-bus.txt, peci-adapter.txt and peci-client.txt into peci.txt.
* Fixed and swept documents to drop some incorrect or unnecessary
  descriptions.
* Fixed device tree to make unit-address format use reg contents.
* Simplified bit manipulations using <linux/bitfield.h>.
* Made client CPU model checking use <asm/intel-family.h> if available.
* Modified adapter heap allocation method to use kobject reference count
  based.
* Added the low-level PECI xfer IOCTL again to support the Redfish
  requirement.
* Added PM domain attach/detach code.
* Added logic for device instantiation through sysfs.
* Fix a bug of interrupt status checking code in peci-aspeed driver.

Changes since v2:
* Divided peci-hwmon driver into two drivers, peci-cputemp and
  peci-dimmtemp.
* Added generic dt binding documents for PECI bus, adapter and client.
* Removed in_atomic() call from the PECI core driver.
* Improved PECI commands masking logic.
* Added permission check logic for PECI ioctls.
* Removed unnecessary type casts.
* Fixed some invalid error return codes.
* Added the mark_updated() function to improve update interval checking
  logic.
* Fixed a bug in populated DIMM checking function.
* Fixed some typo, grammar and style issues in documents.
* Rewrote hwmon drivers to use devm_hwmon_device_register_with_info API.
* Made peci_match_id() function as a static.
* Replaced a deprecated create_singlethread_workqueue() call with an
  alloc_ordered_workqueue() call.
* Reordered local variable definitions in reversed xmas tree notation.
* Listed up client CPUs that can be supported by peci-cputemp and
  peci-dimmtemp hwmon drivers.
* Added CPU generation detection logic which checks CPUID signature through
  PECI connection.
* Improved interrupt handling logic in the Aspeed PECI adapter driver.
* Fixed SPDX license identifier style in header files.
* Changed some macros in peci.h to static inline functions.
* Dropped sleepable context checking code in peci-core.
* Adjusted rt_mutex protection scope in peci-core.
* Moved adapter->xfer() checking code into peci_register_adapter().
* Improved PECI command retry checking logic.
* Changed ioctl base from 'P' to 0xb6 to avoid confiliction and updated
  ioctl-number.txt to reflect the ioctl number of PECI subsystem.
* Added a comment to describe PECI retry action.
* Simplified return code handling of peci_ioctl_ping().
* Changed type of peci_ioctl_fn[] to static const.
* Fixed range checking code for valid PECI commands.
* Fixed the error return code on invalid PECI commands.
* Fixed incorrect definitions of PECI ioctl and its handling logic.

Changes since v1:
* Additionally implemented a core driver to support PECI linux bus driver
  model.
* Modified Aspeed PECI driver to make that to be an adapter driver in PECI
  bus.
* Modified PECI hwmon driver to make that to be a client driver in PECI
  bus.
* Simplified hwmon driver attribute labels and removed redundant strings.
* Removed core_nums from device tree setting of hwmon driver and modified
  core number detection logic to check the resolved_core register in client
  CPU's local PCI configuration area.
* Removed dimm_nums from device tree setting of hwmon driver and added
  populated DIMM detection logic to support dynamic creation.
* Removed indexing gap on core temperature and DIMM temperature attributes.
* Improved hwmon registration and dynamic attribute creation logic.
* Fixed structure definitions in PECI uapi header to make that use __u8,
  __u16 and etc.
* Modified wait_for_completion_interruptible_timeout error handling logic
  in Aspeed PECI driver to deliver errors correctly.
* Removed low-level xfer command from ioctl and kept only high-level PECI
  command suite as ioctls.
* Fixed I/O timeout logic in Aspeed PECI driver using ktime.
* Added a function into hwmon driver to simplify update delay checking.
* Added a function into hwmon driver to convert 10.6 to millidegree.
* Dropped non-standard attributes in hwmon driver.
* Fixed OF table for hwmon to make it indicate as a PECI client of Intel
  CPU target.
* Added a maintainer of PECI subsystem into MAINTAINERS document.

Jae Hyun Yoo (13):
  dt-bindings: Add a document of PECI subsystem
  Documentation: ioctl: Add ioctl numbers for PECI subsystem
  peci: Add support for PECI bus driver core
  dt-bindings: Add a document of PECI adapter driver for ASPEED
    AST24xx/25xx SoCs
  ARM: dts: aspeed: peci: Add PECI node
  peci: Add a PECI adapter driver for Aspeed AST24xx/AST25xx
  dt-bindings: mfd: Add a document for PECI client MFD
  mfd: intel-peci-client: Add PECI client MFD driver
  dt-bindings: hwmon: Add documents for PECI hwmon client drivers
  Documentation: hwmon: Add documents for PECI hwmon client drivers
  hwmon: Add PECI cputemp driver
  hwmon: Add PECI dimmtemp driver
  Add maintainers for the PECI subsystem

 .../bindings/hwmon/peci-cputemp.txt           |   11 +
 .../bindings/hwmon/peci-dimmtemp.txt          |   12 +
 .../bindings/mfd/intel-peci-client.txt        |   34 +
 .../devicetree/bindings/peci/peci-aspeed.txt  |   57 +
 .../devicetree/bindings/peci/peci.txt         |   60 +
 Documentation/hwmon/peci-cputemp              |   78 +
 Documentation/hwmon/peci-dimmtemp             |   50 +
 Documentation/ioctl/ioctl-number.txt          |    2 +
 MAINTAINERS                                   |   12 +
 arch/arm/boot/dts/aspeed-g4.dtsi              |   26 +
 arch/arm/boot/dts/aspeed-g5.dtsi              |   26 +
 drivers/Kconfig                               |    2 +
 drivers/Makefile                              |    1 +
 drivers/hwmon/Kconfig                         |   28 +
 drivers/hwmon/Makefile                        |    2 +
 drivers/hwmon/peci-cputemp.c                  |  401 +++++
 drivers/hwmon/peci-dimmtemp.c                 |  295 ++++
 drivers/mfd/Kconfig                           |   14 +
 drivers/mfd/Makefile                          |    1 +
 drivers/mfd/intel-peci-client.c               |  182 +++
 drivers/peci/Kconfig                          |   39 +
 drivers/peci/Makefile                         |    9 +
 drivers/peci/peci-aspeed.c                    |  498 ++++++
 drivers/peci/peci-core.c                      | 1438 +++++++++++++++++
 include/linux/mfd/intel-peci-client.h         |   81 +
 include/linux/peci.h                          |  104 ++
 include/uapi/linux/peci-ioctl.h               |  265 +++
 27 files changed, 3728 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/peci-cputemp.txt
 create mode 100644 Documentation/devicetree/bindings/hwmon/peci-dimmtemp.txt
 create mode 100644 Documentation/devicetree/bindings/mfd/intel-peci-client.txt
 create mode 100644 Documentation/devicetree/bindings/peci/peci-aspeed.txt
 create mode 100644 Documentation/devicetree/bindings/peci/peci.txt
 create mode 100644 Documentation/hwmon/peci-cputemp
 create mode 100644 Documentation/hwmon/peci-dimmtemp
 create mode 100644 drivers/hwmon/peci-cputemp.c
 create mode 100644 drivers/hwmon/peci-dimmtemp.c
 create mode 100644 drivers/mfd/intel-peci-client.c
 create mode 100644 drivers/peci/Kconfig
 create mode 100644 drivers/peci/Makefile
 create mode 100644 drivers/peci/peci-aspeed.c
 create mode 100644 drivers/peci/peci-core.c
 create mode 100644 include/linux/mfd/intel-peci-client.h
 create mode 100644 include/linux/peci.h
 create mode 100644 include/uapi/linux/peci-ioctl.h

-- 
2.17.1

[PATCH linux-next v6 01/13] dt-bindings: Add a document of PECI subsystem

[Jae Hyun Yoo]

This commit adds a document of generic PECI bus, adapter and client
driver.

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Reviewed-by: Haiyue Wang <haiyue.wang@linux.intel.com>
Reviewed-by: James Feist <james.feist@linux.intel.com>
Reviewed-by: Vernon Mauery <vernon.mauery@linux.intel.com>
Cc: Andrew Jeffery <andrew@aj.id.au>
Cc: Joel Stanley <joel@jms.id.au>
---
 .../devicetree/bindings/peci/peci.txt         | 60 +++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/peci/peci.txt

diff --git a/Documentation/devicetree/bindings/peci/peci.txt b/Documentation/devicetree/bindings/peci/peci.txt
new file mode 100644
index 000000000000..5583aa80b78a
--- /dev/null
+++ b/Documentation/devicetree/bindings/peci/peci.txt
@@ -0,0 +1,60 @@
+Generic device tree configuration for PECI buses
+================================================
+
+Required properties:
+- compatible     : Should be "simple-bus".
+- #address-cells : Should be present if the device has sub-nodes.
+- #size-cells    : Should be present if the device has sub-nodes.
+- ranges         : Should contain PECI controller registers ranges.
+
+Example:
+	peci: peci@10000000 {
+		compatible = "simple-bus";
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0x0 0x10000000 0x1000>;
+	};
+
+Generic device tree configuration for PECI adapters
+===================================================
+
+Required properties:
+- #address-cells : Should be <1>. Read more about client addresses below.
+- #size-cells    : Should be <0>. Read more about client addresses below.
+
+The cells properties above define that an address of CPU clients of a PECI bus
+are described by a single value.
+
+Example:
+	peci0: peci-bus@0 {
+		compatible = "vendor,soc-peci";
+		reg = <0x0 0x1000>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+	};
+
+Generic device tree configuration for PECI clients
+==================================================
+
+Required properties:
+- compatible : Should contain name of PECI client.
+- reg        : Should contain address of a client CPU. Address range of CPU
+	       clients starts from 0x30 based on PECI specification.
+
+Example:
+	peci-bus@0 {
+		compatible = "vendor,soc-peci";
+		reg = <0x0 0x1000>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		peci-client@30 {
+			compatible = "vendor,peci-client";
+			reg = <0x30>;
+		};
+
+		peci-client@31 {
+			compatible = "vendor,peci-client";
+			reg = <0x31>;
+		};
+	};
-- 
2.17.1

[PATCH linux-next v6 04/13] dt-bindings: Add a document of PECI adapter driver for ASPEED AST24xx/25xx SoCs

[Jae Hyun Yoo]

This commit adds a dt-bindings document of PECI adapter driver for ASPEED
AST24xx/25xx SoCs.

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Reviewed-by: Haiyue Wang <haiyue.wang@linux.intel.com>
Reviewed-by: James Feist <james.feist@linux.intel.com>
Reviewed-by: Vernon Mauery <vernon.mauery@linux.intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Jason M Biils <jason.m.bills@linux.intel.com>
Cc: Milton Miller II <miltonm@us.ibm.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Ryan Chen <ryan_chen@aspeedtech.com>
---
 .../devicetree/bindings/peci/peci-aspeed.txt  | 57 +++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/peci/peci-aspeed.txt

diff --git a/Documentation/devicetree/bindings/peci/peci-aspeed.txt b/Documentation/devicetree/bindings/peci/peci-aspeed.txt
new file mode 100644
index 000000000000..8c35f905589d
--- /dev/null
+++ b/Documentation/devicetree/bindings/peci/peci-aspeed.txt
@@ -0,0 +1,57 @@
+Device tree configuration for PECI buses on the AST24XX and AST25XX SoCs.
+
+Required properties:
+- compatible        : Should be "aspeed,ast2400-peci" or "aspeed,ast2500-peci"
+		      - aspeed,ast2400-peci: ASPEED AST2400 family PECI
+					     controller
+		      - aspeed,ast2500-peci: ASPEED AST2500 family PECI
+					     controller
+- reg               : Should contain PECI controller registers location and
+		      length.
+- #address-cells    : Should be <1> required to define a client address.
+- #size-cells       : Should be <0> required to define a client address.
+- interrupts        : Should contain PECI controller interrupt.
+- clocks            : Should contain clock source for PECI controller. Should
+		      reference the external oscillator clock in the second
+		      cell.
+- resets            : Should contain phandle to reset controller with the reset
+		      number in the second cell.
+- clock-frequency   : Should contain the operation frequency of PECI controller
+		      in units of Hz.
+		      187500 ~ 24000000
+
+Optional properties:
+- msg-timing        : 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       : 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 the time frame in which the 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:
+	peci0: peci-bus@0 {
+		compatible = "aspeed,ast2500-peci";
+		reg = <0x0 0x60>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		interrupts = <15>;
+		clocks = <&syscon ASPEED_CLK_GATE_REFCLK>;
+		resets = <&syscon ASPEED_RESET_PECI>;
+		clock-frequency = <24000000>;
+		msg-timing = <1>;
+		addr-timing = <1>;
+		rd-sampling-point = <8>;
+		cmd-timeout-ms = <1000>;
+	};
-- 
2.17.1

[PATCH linux-next v6 05/13] ARM: dts: aspeed: peci: Add PECI node

[Jae Hyun Yoo]

This commit adds PECI bus/adapter node of AST24xx/AST25xx into
aspeed-g4 and aspeed-g5.

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Reviewed-by: Haiyue Wang <haiyue.wang@linux.intel.com>
Reviewed-by: James Feist <james.feist@linux.intel.com>
Reviewed-by: Vernon Mauery <vernon.mauery@linux.intel.com>
Cc: Jason M Biils <jason.m.bills@linux.intel.com>
Cc: Ryan Chen <ryan_chen@aspeedtech.com>
---
 arch/arm/boot/dts/aspeed-g4.dtsi | 26 ++++++++++++++++++++++++++
 arch/arm/boot/dts/aspeed-g5.dtsi | 26 ++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/arch/arm/boot/dts/aspeed-g4.dtsi b/arch/arm/boot/dts/aspeed-g4.dtsi
index 75df1573380e..f7b83298e25f 100644
--- a/arch/arm/boot/dts/aspeed-g4.dtsi
+++ b/arch/arm/boot/dts/aspeed-g4.dtsi
@@ -29,6 +29,7 @@
 		serial3 = &uart4;
 		serial4 = &uart5;
 		serial5 = &vuart;
+		peci0 = &peci0;
 	};
 
 	cpus {
@@ -295,6 +296,13 @@
 				};
 			};
 
+			peci: peci@1e78b000 {
+				compatible = "simple-bus";
+				#address-cells = <1>;
+				#size-cells = <1>;
+				ranges = <0x0 0x1e78b000 0x60>;
+			};
+
 			uart2: serial@1e78d000 {
 				compatible = "ns16550a";
 				reg = <0x1e78d000 0x20>;
@@ -338,6 +346,24 @@
 	};
 };
 
+&peci {
+	peci0: peci-bus@0 {
+		compatible = "aspeed,ast2400-peci";
+		reg = <0x0 0x60>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		interrupts = <15>;
+		clocks = <&syscon ASPEED_CLK_GATE_REFCLK>;
+		resets = <&syscon ASPEED_RESET_PECI>;
+		clock-frequency = <24000000>;
+		msg-timing = <1>;
+		addr-timing = <1>;
+		rd-sampling-point = <8>;
+		cmd-timeout-ms = <1000>;
+		status = "disabled";
+	};
+};
+
 &i2c {
 	i2c_ic: interrupt-controller@0 {
 		#interrupt-cells = <1>;
diff --git a/arch/arm/boot/dts/aspeed-g5.dtsi b/arch/arm/boot/dts/aspeed-g5.dtsi
index 17f2714d18a7..f8eccdaacedc 100644
--- a/arch/arm/boot/dts/aspeed-g5.dtsi
+++ b/arch/arm/boot/dts/aspeed-g5.dtsi
@@ -29,6 +29,7 @@
 		serial3 = &uart4;
 		serial4 = &uart5;
 		serial5 = &vuart;
+		peci0 = &peci0;
 	};
 
 	cpus {
@@ -352,6 +353,13 @@
 				};
 			};
 
+			peci: peci@1e78b000 {
+				compatible = "simple-bus";
+				#address-cells = <1>;
+				#size-cells = <1>;
+				ranges = <0x0 0x1e78b000 0x60>;
+			};
+
 			uart2: serial@1e78d000 {
 				compatible = "ns16550a";
 				reg = <0x1e78d000 0x20>;
@@ -395,6 +403,24 @@
 	};
 };
 
+&peci {
+	peci0: peci-bus@0 {
+		compatible = "aspeed,ast2500-peci";
+		reg = <0x0 0x60>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		interrupts = <15>;
+		clocks = <&syscon ASPEED_CLK_GATE_REFCLK>;
+		resets = <&syscon ASPEED_RESET_PECI>;
+		clock-frequency = <24000000>;
+		msg-timing = <1>;
+		addr-timing = <1>;
+		rd-sampling-point = <8>;
+		cmd-timeout-ms = <1000>;
+		status = "disabled";
+	};
+};
+
 &i2c {
 	i2c_ic: interrupt-controller@0 {
 		#interrupt-cells = <1>;
-- 
2.17.1

[PATCH linux-next v6 07/13] dt-bindings: mfd: Add a document for PECI client MFD

[Jae Hyun Yoo]

This commit adds a dt-bindings document for PECI client MFD.

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Cc: Andrew Jeffery <andrew@aj.id.au>
Cc: James Feist <james.feist@linux.intel.com>
Cc: Jason M Biils <jason.m.bills@linux.intel.com>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Vernon Mauery <vernon.mauery@linux.intel.com>
---
 .../bindings/mfd/intel-peci-client.txt        | 34 +++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mfd/intel-peci-client.txt

diff --git a/Documentation/devicetree/bindings/mfd/intel-peci-client.txt b/Documentation/devicetree/bindings/mfd/intel-peci-client.txt
new file mode 100644
index 000000000000..cb341e363add
--- /dev/null
+++ b/Documentation/devicetree/bindings/mfd/intel-peci-client.txt
@@ -0,0 +1,34 @@
+* Intel PECI client bindings
+
+PECI (Platform Environment Control Interface) is a one-wire bus interface that
+provides a communication channel from PECI clients in 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
+- Platform Manageability
+- Processor Interface Tuning and Diagnostics
+- Failure Analysis
+
+Required properties:
+- compatible : Should be "intel,peci-client".
+- reg        : Should contain address of a client CPU. Address range of CPU
+	       clients starts from 0x30 based on PECI specification.
+
+Example:
+	peci-bus@0 {
+		compatible = "vendor,soc-peci";
+		reg = <0x0 0x1000>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		peci-client@30 {
+			compatible = "intel,peci-client";
+			reg = <0x30>;
+		};
+
+		peci-client@31 {
+			compatible = "intel,peci-client";
+			reg = <0x31>;
+		};
+	};
-- 
2.17.1

[PATCH linux-next v6 09/13] dt-bindings: hwmon: Add documents for PECI hwmon client drivers

[Jae Hyun Yoo]

This commit adds dt-bindings documents for PECI hwmon client drivers.

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Reviewed-by: Haiyue Wang <haiyue.wang@linux.intel.com>
Reviewed-by: James Feist <james.feist@linux.intel.com>
Reviewed-by: Vernon Mauery <vernon.mauery@linux.intel.com>
Cc: Andrew Jeffery <andrew@aj.id.au>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jason M Biils <jason.m.bills@linux.intel.com>
Cc: Joel Stanley <joel@jms.id.au>
---
 .../devicetree/bindings/hwmon/peci-cputemp.txt       | 11 +++++++++++
 .../devicetree/bindings/hwmon/peci-dimmtemp.txt      | 12 ++++++++++++
 2 files changed, 23 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/peci-cputemp.txt
 create mode 100644 Documentation/devicetree/bindings/hwmon/peci-dimmtemp.txt

diff --git a/Documentation/devicetree/bindings/hwmon/peci-cputemp.txt b/Documentation/devicetree/bindings/hwmon/peci-cputemp.txt
new file mode 100644
index 000000000000..19c7da57deab
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/peci-cputemp.txt
@@ -0,0 +1,11 @@
+Bindings for Intel PECI (Platform Environment Control Interface) cputemp driver.
+
+Required properties:
+- compatible : Should be "intel,peci-cputemp".
+
+This node is a subnode of the PECI client MFD.
+
+Example:
+	peci-cputemp {
+		compatible = "intel,peci-cputemp";
+	};
diff --git a/Documentation/devicetree/bindings/hwmon/peci-dimmtemp.txt b/Documentation/devicetree/bindings/hwmon/peci-dimmtemp.txt
new file mode 100644
index 000000000000..08ce163ba831
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/peci-dimmtemp.txt
@@ -0,0 +1,12 @@
+Bindings for Intel PECI (Platform Environment Control Interface) dimmtemp
+driver.
+
+Required properties:
+- compatible : Should be "intel,peci-dimmtemp".
+
+This node is a subnode of the PECI client MFD.
+
+Example:
+	peci-dimmtemp@30 {
+		compatible = "intel,peci-dimmtemp";
+	};
\ No newline at end of file
-- 
2.17.1

Re: [PATCH linux-next v6 01/13] dt-bindings: Add a document of PECI subsystem

[Rob Herring]

On Thu, Jun 21, 2018 at 12:39:47PM -0700, Jae Hyun Yoo wrote:
> This commit adds a document of generic PECI bus, adapter and client
> driver.
> 
> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
> Reviewed-by: Haiyue Wang <haiyue.wang@linux.intel.com>
> Reviewed-by: James Feist <james.feist@linux.intel.com>
> Reviewed-by: Vernon Mauery <vernon.mauery@linux.intel.com>
> Cc: Andrew Jeffery <andrew@aj.id.au>
> Cc: Joel Stanley <joel@jms.id.au>
> ---
>  .../devicetree/bindings/peci/peci.txt         | 60 +++++++++++++++++++
>  1 file changed, 60 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/peci/peci.txt
> 
> diff --git a/Documentation/devicetree/bindings/peci/peci.txt b/Documentation/devicetree/bindings/peci/peci.txt
> new file mode 100644
> index 000000000000..5583aa80b78a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/peci/peci.txt
> @@ -0,0 +1,60 @@
> +Generic device tree configuration for PECI buses
> +================================================
> +
> +Required properties:
> +- compatible     : Should be "simple-bus".
> +- #address-cells : Should be present if the device has sub-nodes.
> +- #size-cells    : Should be present if the device has sub-nodes.
> +- ranges         : Should contain PECI controller registers ranges.
> +
> +Example:
> +	peci: peci@10000000 {
> +		compatible = "simple-bus";
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges = <0x0 0x10000000 0x1000>;
> +	};

I don't think you need this section. It's just the parent of the 
controller, right?

> +
> +Generic device tree configuration for PECI adapters
> +===================================================
> +
> +Required properties:
> +- #address-cells : Should be <1>. Read more about client addresses below.
> +- #size-cells    : Should be <0>. Read more about client addresses below.
> +
> +The cells properties above define that an address of CPU clients of a PECI bus
> +are described by a single value.
> +
> +Example:
> +	peci0: peci-bus@0 {
> +		compatible = "vendor,soc-peci";
> +		reg = <0x0 0x1000>;
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +	};
> +
> +Generic device tree configuration for PECI clients
> +==================================================
> +
> +Required properties:
> +- compatible : Should contain name of PECI client.
> +- reg        : Should contain address of a client CPU. Address range of CPU
> +	       clients starts from 0x30 based on PECI specification.
> +
> +Example:
> +	peci-bus@0 {
> +		compatible = "vendor,soc-peci";
> +		reg = <0x0 0x1000>;
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		peci-client@30 {
> +			compatible = "vendor,peci-client";
> +			reg = <0x30>;
> +		};
> +
> +		peci-client@31 {
> +			compatible = "vendor,peci-client";
> +			reg = <0x31>;
> +		};
> +	};
> -- 
> 2.17.1
> 

Re: [PATCH linux-next v6 04/13] dt-bindings: Add a document of PECI adapter driver for ASPEED AST24xx/25xx SoCs

[Rob Herring]

On Thu, Jun 21, 2018 at 12:40:24PM -0700, Jae Hyun Yoo wrote:
> This commit adds a dt-bindings document of PECI adapter driver for ASPEED
> AST24xx/25xx SoCs.
> 
> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
> Reviewed-by: Haiyue Wang <haiyue.wang@linux.intel.com>
> Reviewed-by: James Feist <james.feist@linux.intel.com>
> Reviewed-by: Vernon Mauery <vernon.mauery@linux.intel.com>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Greg KH <gregkh@linuxfoundation.org>
> Cc: Jason M Biils <jason.m.bills@linux.intel.com>
> Cc: Milton Miller II <miltonm@us.ibm.com>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Cc: Ryan Chen <ryan_chen@aspeedtech.com>
> ---
>  .../devicetree/bindings/peci/peci-aspeed.txt  | 57 +++++++++++++++++++
>  1 file changed, 57 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/peci/peci-aspeed.txt
> 
> diff --git a/Documentation/devicetree/bindings/peci/peci-aspeed.txt b/Documentation/devicetree/bindings/peci/peci-aspeed.txt
> new file mode 100644
> index 000000000000..8c35f905589d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/peci/peci-aspeed.txt
> @@ -0,0 +1,57 @@
> +Device tree configuration for PECI buses on the AST24XX and AST25XX SoCs.
> +
> +Required properties:
> +- compatible        : Should be "aspeed,ast2400-peci" or "aspeed,ast2500-peci"
> +		      - aspeed,ast2400-peci: ASPEED AST2400 family PECI
> +					     controller
> +		      - aspeed,ast2500-peci: ASPEED AST2500 family PECI
> +					     controller

Just this is sufficient:

Should be one of: 
	"aspeed,ast2400-peci"
	"aspeed,ast2500-peci"

With that,

Reviewed-by: Rob Herring <robh@kernel.org>

> +- reg               : Should contain PECI controller registers location and
> +		      length.
> +- #address-cells    : Should be <1> required to define a client address.
> +- #size-cells       : Should be <0> required to define a client address.
> +- interrupts        : Should contain PECI controller interrupt.
> +- clocks            : Should contain clock source for PECI controller. Should
> +		      reference the external oscillator clock in the second
> +		      cell.
> +- resets            : Should contain phandle to reset controller with the reset
> +		      number in the second cell.
> +- clock-frequency   : Should contain the operation frequency of PECI controller
> +		      in units of Hz.
> +		      187500 ~ 24000000
> +
> +Optional properties:
> +- msg-timing        : 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       : 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 the time frame in which the 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:
> +	peci0: peci-bus@0 {
> +		compatible = "aspeed,ast2500-peci";
> +		reg = <0x0 0x60>;
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		interrupts = <15>;
> +		clocks = <&syscon ASPEED_CLK_GATE_REFCLK>;
> +		resets = <&syscon ASPEED_RESET_PECI>;
> +		clock-frequency = <24000000>;
> +		msg-timing = <1>;
> +		addr-timing = <1>;
> +		rd-sampling-point = <8>;
> +		cmd-timeout-ms = <1000>;
> +	};
> -- 
> 2.17.1
> 

Re: [PATCH linux-next v6 01/13] dt-bindings: Add a document of PECI subsystem

[Jae Hyun Yoo]

Hi Rob,

Thanks for the review. Please see my inline answer.

On 7/3/2018 9:47 AM, Rob Herring wrote:
> On Thu, Jun 21, 2018 at 12:39:47PM -0700, Jae Hyun Yoo wrote:
>> This commit adds a document of generic PECI bus, adapter and client
>> driver.
>>
>> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
>> Reviewed-by: Haiyue Wang <haiyue.wang@linux.intel.com>
>> Reviewed-by: James Feist <james.feist@linux.intel.com>
>> Reviewed-by: Vernon Mauery <vernon.mauery@linux.intel.com>
>> Cc: Andrew Jeffery <andrew@aj.id.au>
>> Cc: Joel Stanley <joel@jms.id.au>
>> ---
>>   .../devicetree/bindings/peci/peci.txt         | 60 +++++++++++++++++++
>>   1 file changed, 60 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/peci/peci.txt
>>
>> diff --git a/Documentation/devicetree/bindings/peci/peci.txt b/Documentation/devicetree/bindings/peci/peci.txt
>> new file mode 100644
>> index 000000000000..5583aa80b78a
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/peci/peci.txt
>> @@ -0,0 +1,60 @@
>> +Generic device tree configuration for PECI buses
>> +================================================
>> +
>> +Required properties:
>> +- compatible     : Should be "simple-bus".
>> +- #address-cells : Should be present if the device has sub-nodes.
>> +- #size-cells    : Should be present if the device has sub-nodes.
>> +- ranges         : Should contain PECI controller registers ranges.
>> +
>> +Example:
>> +	peci: peci@10000000 {
>> +		compatible = "simple-bus";
>> +		#address-cells = <1>;
>> +		#size-cells = <1>;
>> +		ranges = <0x0 0x10000000 0x1000>;
>> +	};
> 
> I don't think you need this section. It's just the parent of the
> controller, right?
> 

Right. I'll drop this section out.

Thanks a lot,

Jae

>> +
>> +Generic device tree configuration for PECI adapters
>> +===================================================
>> +
>> +Required properties:
>> +- #address-cells : Should be <1>. Read more about client addresses below.
>> +- #size-cells    : Should be <0>. Read more about client addresses below.
>> +
>> +The cells properties above define that an address of CPU clients of a PECI bus
>> +are described by a single value.
>> +
>> +Example:
>> +	peci0: peci-bus@0 {
>> +		compatible = "vendor,soc-peci";
>> +		reg = <0x0 0x1000>;
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>> +	};
>> +
>> +Generic device tree configuration for PECI clients
>> +==================================================
>> +
>> +Required properties:
>> +- compatible : Should contain name of PECI client.
>> +- reg        : Should contain address of a client CPU. Address range of CPU
>> +	       clients starts from 0x30 based on PECI specification.
>> +
>> +Example:
>> +	peci-bus@0 {
>> +		compatible = "vendor,soc-peci";
>> +		reg = <0x0 0x1000>;
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>> +
>> +		peci-client@30 {
>> +			compatible = "vendor,peci-client";
>> +			reg = <0x30>;
>> +		};
>> +
>> +		peci-client@31 {
>> +			compatible = "vendor,peci-client";
>> +			reg = <0x31>;
>> +		};
>> +	};
>> -- 
>> 2.17.1
>>

Re: [PATCH linux-next v6 07/13] dt-bindings: mfd: Add a document for PECI client MFD

[Rob Herring]

On Thu, Jun 21, 2018 at 12:40:54PM -0700, Jae Hyun Yoo wrote:
> This commit adds a dt-bindings document for PECI client MFD.

This and the next patch still have the same issues I've outlined in at 
least 2 prior versions.
 
> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
> Cc: Andrew Jeffery <andrew@aj.id.au>
> Cc: James Feist <james.feist@linux.intel.com>
> Cc: Jason M Biils <jason.m.bills@linux.intel.com>
> Cc: Joel Stanley <joel@jms.id.au>
> Cc: Vernon Mauery <vernon.mauery@linux.intel.com>
> ---
>  .../bindings/mfd/intel-peci-client.txt        | 34 +++++++++++++++++++
>  1 file changed, 34 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mfd/intel-peci-client.txt
> 
> diff --git a/Documentation/devicetree/bindings/mfd/intel-peci-client.txt b/Documentation/devicetree/bindings/mfd/intel-peci-client.txt
> new file mode 100644
> index 000000000000..cb341e363add
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/intel-peci-client.txt
> @@ -0,0 +1,34 @@
> +* Intel PECI client bindings
> +
> +PECI (Platform Environment Control Interface) is a one-wire bus interface that
> +provides a communication channel from PECI clients in 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
> +- Platform Manageability
> +- Processor Interface Tuning and Diagnostics
> +- Failure Analysis
> +
> +Required properties:
> +- compatible : Should be "intel,peci-client".
> +- reg        : Should contain address of a client CPU. Address range of CPU
> +	       clients starts from 0x30 based on PECI specification.
> +
> +Example:
> +	peci-bus@0 {
> +		compatible = "vendor,soc-peci";
> +		reg = <0x0 0x1000>;
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		peci-client@30 {
> +			compatible = "intel,peci-client";
> +			reg = <0x30>;
> +		};
> +
> +		peci-client@31 {
> +			compatible = "intel,peci-client";
> +			reg = <0x31>;
> +		};
> +	};
> -- 
> 2.17.1
> 

Re: [PATCH linux-next v6 04/13] dt-bindings: Add a document of PECI adapter driver for ASPEED AST24xx/25xx SoCs

[Jae Hyun Yoo]

Hi Rob,

Thanks a lot for the review. Please check my inline answer.

On 7/3/2018 9:51 AM, Rob Herring wrote:
> On Thu, Jun 21, 2018 at 12:40:24PM -0700, Jae Hyun Yoo wrote:
>> This commit adds a dt-bindings document of PECI adapter driver for ASPEED
>> AST24xx/25xx SoCs.
>>
>> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
>> Reviewed-by: Haiyue Wang <haiyue.wang@linux.intel.com>
>> Reviewed-by: James Feist <james.feist@linux.intel.com>
>> Reviewed-by: Vernon Mauery <vernon.mauery@linux.intel.com>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Cc: Greg KH <gregkh@linuxfoundation.org>
>> Cc: Jason M Biils <jason.m.bills@linux.intel.com>
>> Cc: Milton Miller II <miltonm@us.ibm.com>
>> Cc: Pavel Machek <pavel@ucw.cz>
>> Cc: Robin Murphy <robin.murphy@arm.com>
>> Cc: Ryan Chen <ryan_chen@aspeedtech.com>
>> ---
>>   .../devicetree/bindings/peci/peci-aspeed.txt  | 57 +++++++++++++++++++
>>   1 file changed, 57 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/peci/peci-aspeed.txt
>>
>> diff --git a/Documentation/devicetree/bindings/peci/peci-aspeed.txt b/Documentation/devicetree/bindings/peci/peci-aspeed.txt
>> new file mode 100644
>> index 000000000000..8c35f905589d
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/peci/peci-aspeed.txt
>> @@ -0,0 +1,57 @@
>> +Device tree configuration for PECI buses on the AST24XX and AST25XX SoCs.
>> +
>> +Required properties:
>> +- compatible        : Should be "aspeed,ast2400-peci" or "aspeed,ast2500-peci"
>> +		      - aspeed,ast2400-peci: ASPEED AST2400 family PECI
>> +					     controller
>> +		      - aspeed,ast2500-peci: ASPEED AST2500 family PECI
>> +					     controller
> 
> Just this is sufficient:
> 
> Should be one of:
> 	"aspeed,ast2400-peci"
> 	"aspeed,ast2500-peci"
> 
> With that,
> 
> Reviewed-by: Rob Herring <robh@kernel.org>
> 

Thanks! I'll change it as you commented out.

Jae

>> +- reg               : Should contain PECI controller registers location and
>> +		      length.
>> +- #address-cells    : Should be <1> required to define a client address.
>> +- #size-cells       : Should be <0> required to define a client address.
>> +- interrupts        : Should contain PECI controller interrupt.
>> +- clocks            : Should contain clock source for PECI controller. Should
>> +		      reference the external oscillator clock in the second
>> +		      cell.
>> +- resets            : Should contain phandle to reset controller with the reset
>> +		      number in the second cell.
>> +- clock-frequency   : Should contain the operation frequency of PECI controller
>> +		      in units of Hz.
>> +		      187500 ~ 24000000
>> +
>> +Optional properties:
>> +- msg-timing        : 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       : 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 the time frame in which the 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:
>> +	peci0: peci-bus@0 {
>> +		compatible = "aspeed,ast2500-peci";
>> +		reg = <0x0 0x60>;
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>> +		interrupts = <15>;
>> +		clocks = <&syscon ASPEED_CLK_GATE_REFCLK>;
>> +		resets = <&syscon ASPEED_RESET_PECI>;
>> +		clock-frequency = <24000000>;
>> +		msg-timing = <1>;
>> +		addr-timing = <1>;
>> +		rd-sampling-point = <8>;
>> +		cmd-timeout-ms = <1000>;
>> +	};
>> -- 
>> 2.17.1
>>

Re: [PATCH linux-next v6 07/13] dt-bindings: mfd: Add a document for PECI client MFD

[Jae Hyun Yoo]

Hi Rob,

Thanks for the review. Please see my inline answer.

On 7/3/2018 9:58 AM, Rob Herring wrote:
> On Thu, Jun 21, 2018 at 12:40:54PM -0700, Jae Hyun Yoo wrote:
>> This commit adds a dt-bindings document for PECI client MFD.
> 
> This and the next patch still have the same issues I've outlined in at
> least 2 prior versions.
>   

Okay. I think the next patch (9/13) for hwmon dt-bindings document
is not needed anymore because those were already added in MFD driver
implementation in the patch 8/13. Please correct me if it's not
you pointed.

>> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
>> Cc: Andrew Jeffery <andrew@aj.id.au>
>> Cc: James Feist <james.feist@linux.intel.com>
>> Cc: Jason M Biils <jason.m.bills@linux.intel.com>
>> Cc: Joel Stanley <joel@jms.id.au>
>> Cc: Vernon Mauery <vernon.mauery@linux.intel.com>
>> ---
>>   .../bindings/mfd/intel-peci-client.txt        | 34 +++++++++++++++++++
>>   1 file changed, 34 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/mfd/intel-peci-client.txt
>>
>> diff --git a/Documentation/devicetree/bindings/mfd/intel-peci-client.txt b/Documentation/devicetree/bindings/mfd/intel-peci-client.txt
>> new file mode 100644
>> index 000000000000..cb341e363add
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/mfd/intel-peci-client.txt
>> @@ -0,0 +1,34 @@
>> +* Intel PECI client bindings
>> +
>> +PECI (Platform Environment Control Interface) is a one-wire bus interface that
>> +provides a communication channel from PECI clients in 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
>> +- Platform Manageability
>> +- Processor Interface Tuning and Diagnostics
>> +- Failure Analysis
>> +
>> +Required properties:
>> +- compatible : Should be "intel,peci-client".
>> +- reg        : Should contain address of a client CPU. Address range of CPU
>> +	       clients starts from 0x30 based on PECI specification.
>> +
>> +Example:
>> +	peci-bus@0 {
>> +		compatible = "vendor,soc-peci";
>> +		reg = <0x0 0x1000>;
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>> +
>> +		peci-client@30 {
>> +			compatible = "intel,peci-client";
>> +			reg = <0x30>;
>> +		};
>> +
>> +		peci-client@31 {
>> +			compatible = "intel,peci-client";
>> +			reg = <0x31>;
>> +		};
>> +	};
>> -- 
>> 2.17.1
>>
>