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, 52 insertions, 0 deletions

diff --git a/drivers/platform/x86/intel_pmt_class.h b/drivers/platform/x86/intel_pmt_class.h
new file mode 100644
index 000000000000..de8f8139ba31
--- /dev/null
+++ b/drivers/platform/x86/intel_pmt_class.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _INTEL_PMT_CLASS_H
+#define _INTEL_PMT_CLASS_H
+
+#include <linux/platform_device.h>
+#include <linux/xarray.h>
+#include <linux/types.h>
+#include <linux/bits.h>
+#include <linux/err.h>
+#include <linux/io.h>
+
+/* PMT access types */
+#define ACCESS_BARID		2
+#define ACCESS_LOCAL		3
+
+/* PMT discovery base address/offset register layout */
+#define GET_BIR(v)		((v) & GENMASK(2, 0))
+#define GET_ADDRESS(v)		((v) & GENMASK(31, 3))
+
+struct intel_pmt_entry {
+	struct bin_attribute	pmt_bin_attr;
+	struct kobject		*kobj;
+	void __iomem		*disc_table;
+	void __iomem		*base;
+	unsigned long		base_addr;
+	size_t			size;
+	u32			guid;
+	int			devid;
+};
+
+struct intel_pmt_header {
+	u32	base_offset;
+	u32	size;
+	u32	guid;
+	u8	access_type;
+};
+
+struct intel_pmt_namespace {
+	const char *name;
+	struct xarray *xa;
+	const struct attribute_group *attr_grp;
+	int (*pmt_header_decode)(struct intel_pmt_entry *entry,
+				 struct intel_pmt_header *header,
+				 struct device *dev);
+};
+
+int intel_pmt_dev_create(struct intel_pmt_entry *entry,
+			 struct intel_pmt_namespace *ns,
+			 struct platform_device *pdev, int idx);
+void intel_pmt_dev_destroy(struct intel_pmt_entry *entry,
+			   struct intel_pmt_namespace *ns);
+#endif