On Fri, Jul 17, 2020 at 10:05 PM David E. Box <david.e.box@xxxxxxxxxxxxxxx> 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. > I assume this goes thru MFD tree. > 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 <lkp@xxxxxxxxx> > - 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 | 215 +++++++++ > 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, 742 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 > > -- > 2.20.1 > -- With Best Regards, Andy Shevchenko
