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 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
