Friendly ping.
On Wed, 2020-07-29 at 14:37 -0700, David E. Box wrote:
> Intel Platform Monitoring Technology (PMT) is an architecture for
> enumerating and accessing hardware monitoring capabilities on a
> device.
> With customers increasingly asking for hardware telemetry, engineers
> not
> only have to figure out how to measure and collect data, but also how
> to
> deliver it and make it discoverable. The latter may be through some
> device
> specific method requiring device specific tools to collect the data.
> This
> in turn requires customers to manage a suite of different tools in
> order to
> collect the differing assortment of monitoring data on their
> systems. Even
> when such information can be provided in kernel drivers, they may
> require
> constant maintenance to update register mappings as they change with
> firmware updates and new versions of hardware. PMT provides a
> solution for
> discovering and reading telemetry from a device through a hardware
> agnostic
> framework that allows for updates to systems without requiring
> patches to
> the kernel or software tools.
>
> PMT defines several capabilities to support collecting monitoring
> data from
> hardware. All are discoverable as separate instances of the PCIE
> Designated
> Vendor extended capability (DVSEC) with the Intel vendor code. The
> DVSEC ID
> field uniquely identifies the capability. Each DVSEC also provides a
> BAR
> offset to a header that defines capability-specific attributes,
> including
> GUID, feature type, offset and length, as well as configuration
> settings
> where applicable. The GUID uniquely identifies the register space of
> any
> monitor data exposed by the capability. The GUID is associated with
> an XML
> file from the vendor that describes the mapping of the register space
> along
> with properties of the monitor data. This allows vendors to perform
> firmware updates that can change the mapping (e.g. add new metrics)
> without
> requiring any changes to drivers or software tools. The new mapping
> is
> confirmed by an updated GUID, read from the hardware, which software
> uses
> with a new XML.
>
> The current capabilities defined by PMT are Telemetry, Watcher, and
> Crashlog. The Telemetry capability provides access to a continuous
> block
> of read only data. The Watcher capability provides access to hardware
> sampling and tracing features. Crashlog provides access to device
> crash
> dumps. While there is some relationship between capabilities
> (Watcher can
> be configured to sample from the Telemetry data set) each exists as
> stand
> alone features with no dependency on any other. The design therefore
> splits
> them into individual, capability specific drivers. MFD is used to
> create
> platform devices for each capability so that they may be managed by
> their
> own driver. The PMT architecture is (for the most part) agnostic to
> the
> type of device it can collect from. Devices nodes are consequently
> generic
> in naming, e.g. /dev/telem<n> and /dev/smplr<n>. Each capability
> driver
> creates a class to manage the list of devices supporting
> it. Software can
> determine which devices support a PMT feature by searching through
> each
> device node entry in the sysfs class folder. It can additionally
> determine
> if a particular device supports a PMT feature by checking for a PMT
> class
> folder in the device folder.
>
> This patch set provides support for the PMT framework, along with
> support
> for Telemetry on Tiger Lake.
>
> Changes from V4:
> - Replace MFD with PMT in driver title
> - Fix commit tags in chronological order
> - Fix includes in alphabetical order
> - Use 'raw' string instead of defines for device names
> - Add an error message when returning an error code for
> unrecognized capability id
> - Use dev_err instead of dev_warn for messages when returning
> an error
> - Change while loop to call pci_find_next_ext_capability once
> - Add missing continue in while loop
> - Keep PCI platform defines using PCI_DEVICE_DATA magic tied to
> the pci_device_id table
> - Comment and kernel message cleanup
>
> Changes from V3:
> - Write out full acronym for DVSEC in PCI patch commit message
> and
> add 'Designated' to comments
> - remove unused variable caught by kernel test robot <
> [email protected]>
> - Add required Co-developed-by signoffs, noted by Andy
> - Allow access using new CAP_PERFMON capability as suggested by
> Alexey Bundankov
> - Fix spacing in Kconfig, noted by Randy
> - Other style changes and fixups suggested by Andy
>
> Changes from V2:
> - In order to handle certain HW bugs from the telemetry
> capability
> driver, create a single platform device per capability
> instead of
> a device per entry. Add the entry data as device resources
> and
> let the capability driver manage them as a set allowing for
> cleaner HW bug resolution.
> - Handle discovery table offset bug in intel_pmt.c
> - Handle overlapping regions in intel_pmt_telemetry.c
> - Add description of sysfs class to testing ABI.
> - Don't check size and count until confirming support for the
> PMT
> capability to avoid bailing out when we need to skip it.
> - Remove unneeded header file. Move code to the intel_pmt.c,
> the
> only place where it's needed.
> - Remove now unused platform data.
> - Add missing header files types.h, bits.h.
> - Rename file name and build options from telem to telemetry.
> - Code cleanup suggested by Andy S.
> - x86 mailing list added.
>
> Changes from V1:
> - In the telemetry driver, set the device in device_create() to
> the parent PCI device (the monitoring device) for clear
> association in sysfs. Was set before to the platform device
> created by the PCI parent.
> - Move telem struct into driver and delete unneeded header
> file.
> - Start telem device numbering from 0 instead of 1. 1 was used
> due to anticipated changes, no longer needed.
> - Use helper macros suggested by Andy S.
> - Rename class to pmt_telemetry, spelling out full name
> - Move monitor device name defines to common header
> - Coding style, spelling, and Makefile/MAINTAINERS ordering
> fixes
>
> David E. Box (3):
> PCI: Add defines for Designated Vendor-Specific Extended Capability
> mfd: Intel Platform Monitoring Technology support
> platform/x86: Intel PMT Telemetry capability driver
>
> .../ABI/testing/sysfs-class-pmt_telemetry | 46 ++
> MAINTAINERS | 6 +
> drivers/mfd/Kconfig | 10 +
> drivers/mfd/Makefile | 1 +
> drivers/mfd/intel_pmt.c | 220 +++++++++
> drivers/platform/x86/Kconfig | 10 +
> drivers/platform/x86/Makefile | 1 +
> drivers/platform/x86/intel_pmt_telemetry.c | 448
> ++++++++++++++++++
> include/uapi/linux/pci_regs.h | 5 +
> 9 files changed, 747 insertions(+)
> create mode 100644 Documentation/ABI/testing/sysfs-class-
> pmt_telemetry
> create mode 100644 drivers/mfd/intel_pmt.c
> create mode 100644 drivers/platform/x86/intel_pmt_telemetry.c
>
