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 < > 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 | 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 >
