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    Subject[PATCH v3 00/10] PECI device driver introduction
    Date
    Introduction of the Platform Environment Control Interface (PECI) bus
    device driver. PECI is a one-wire bus interface that provides a
    communication channel between an Intel processor 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 from 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 from 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.

    Fengguang Wu (1):
    drivers/peci: Add support for PECI bus driver core


    Jae Hyun Yoo (10):
    Documentations: dt-bindings: Add documents of generic PECI bus,
    adapter and client drivers
    Documentations: ioctl: Add ioctl numbers for PECI subsystem
    drivers/peci: Add support for PECI bus driver core
    Documentations: dt-bindings: Add a document of PECI adapter driver for
    Aspeed AST24xx/25xx SoCs
    ARM: dts: aspeed: peci: Add PECI node
    drivers/peci: Add a PECI adapter driver for Aspeed AST24xx/AST25xx
    Documentation: dt-bindings: Add documents for PECI hwmon client
    drivers
    Documentation: hwmon: Add documents for PECI hwmon client drivers
    drivers/hwmon: Add PECI hwmon client drivers
    Add a maintainer for the PECI subsystem

    .../devicetree/bindings/hwmon/peci-cputemp.txt | 24 +
    .../devicetree/bindings/hwmon/peci-dimmtemp.txt | 25 +
    .../devicetree/bindings/peci/peci-adapter.txt | 23 +
    .../devicetree/bindings/peci/peci-aspeed.txt | 60 +
    .../devicetree/bindings/peci/peci-bus.txt | 15 +
    .../devicetree/bindings/peci/peci-client.txt | 25 +
    Documentation/hwmon/peci-cputemp | 88 ++
    Documentation/hwmon/peci-dimmtemp | 50 +
    Documentation/ioctl/ioctl-number.txt | 2 +
    MAINTAINERS | 10 +
    arch/arm/boot/dts/aspeed-g4.dtsi | 25 +
    arch/arm/boot/dts/aspeed-g5.dtsi | 25 +
    drivers/Kconfig | 2 +
    drivers/Makefile | 1 +
    drivers/hwmon/Kconfig | 28 +
    drivers/hwmon/Makefile | 2 +
    drivers/hwmon/peci-cputemp.c | 783 ++++++++++++
    drivers/hwmon/peci-dimmtemp.c | 432 +++++++
    drivers/peci/Kconfig | 45 +
    drivers/peci/Makefile | 9 +
    drivers/peci/peci-aspeed.c | 504 ++++++++
    drivers/peci/peci-core.c | 1291 ++++++++++++++++++++
    include/linux/peci.h | 107 ++
    include/uapi/linux/peci-ioctl.h | 200 +++
    24 files changed, 3776 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/peci/peci-adapter.txt
    create mode 100644 Documentation/devicetree/bindings/peci/peci-aspeed.txt
    create mode 100644 Documentation/devicetree/bindings/peci/peci-bus.txt
    create mode 100644 Documentation/devicetree/bindings/peci/peci-client.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/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/peci.h
    create mode 100644 include/uapi/linux/peci-ioctl.h

    --
    2.16.2

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