platform/x86: Intel PMT class driver

Intel Platform Monitoring Technology is meant to provide a common way to
access telemetry and system metrics.

Register mappings are not provided by the driver. Instead, a GUID is read
from a header for each endpoint. The GUID identifies the device and is to
be used with an XML, provided by the vendor, to discover the available set
of metrics and their register mapping.  This allows firmware updates to
modify the register space without needing to update the driver every time
with new mappings. Firmware writes a new GUID in this case to specify the
new mapping.  Software tools with access to the associated XML file can
then interpret the changes.

The module manages access to all Intel PMT endpoints on a system,
independent of the device exporting them. It creates an intel_pmt class
to manage the devices. For each telemetry endpoint, sysfs files provide
GUID and size information as well as a pointer to the parent device the
telemetry came from. Software may discover the association between
endpoints and devices by iterating through the list in sysfs, or by looking
for the existence of the class folder under the device of interest.  A
binary sysfs attribute of the same name allows software to then read or map
the telemetry space for direct access.

Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

1 files changed, 54 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-intel_pmt b/Documentation/ABI/testing/sysfs-class-intel_pmt
new file mode 100644
index 000000000000..926b5cf95fd1
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-intel_pmt
@@ -0,0 +1,54 @@
+What:		/sys/class/intel_pmt/
+Date:		October 2020
+KernelVersion:	5.10
+Contact:	David Box <david.e.box@linux.intel.com>
+Description:
+		The intel_pmt/ class directory contains information for
+		devices that expose hardware telemetry using Intel Platform
+		Monitoring Technology (PMT)
+
+What:		/sys/class/intel_pmt/telem<x>
+Date:		October 2020
+KernelVersion:	5.10
+Contact:	David Box <david.e.box@linux.intel.com>
+Description:
+		The telem<x> directory contains files describing an instance of
+		a PMT telemetry device that exposes hardware telemetry. Each
+		telem<x> directory has an associated telem file. This file
+		may be opened and mapped or read to access the telemetry space
+		of the device. The register layout of the telemetry space is
+		determined from an XML file that matches the PCI device id and
+		GUID for the device.
+
+What:		/sys/class/intel_pmt/telem<x>/telem
+Date:		October 2020
+KernelVersion:	5.10
+Contact:	David Box <david.e.box@linux.intel.com>
+Description:
+		(RO) The telemetry data for this telemetry device. This file
+		may be mapped or read to obtain the data.
+
+What:		/sys/class/intel_pmt/telem<x>/guid
+Date:		October 2020
+KernelVersion:	5.10
+Contact:	David Box <david.e.box@linux.intel.com>
+Description:
+		(RO) The GUID for this telemetry device. The GUID identifies
+		the version of the XML file for the parent device that is to
+		be used to get the register layout.
+
+What:		/sys/class/intel_pmt/telem<x>/size
+Date:		October 2020
+KernelVersion:	5.10
+Contact:	David Box <david.e.box@linux.intel.com>
+Description:
+		(RO) The size of telemetry region in bytes that corresponds to
+		the mapping size for the telem file.
+
+What:		/sys/class/intel_pmt/telem<x>/offset
+Date:		October 2020
+KernelVersion:	5.10
+Contact:	David Box <david.e.box@linux.intel.com>
+Description:
+		(RO) The offset of telemetry region in bytes that corresponds to
+		the mapping for the telem file.