platform/x86: Intel PMT Telemetry capability driver

PMT Telemetry is a capability of the Intel Platform Monitoring Technology.
The Telemetry capability provides access to device telemetry metrics that
provide hardware performance data to users from read-only register spaces.

With this driver present the intel_pmt directory can be populated with
telem<x> devices. These devices will contain the standard intel_pmt sysfs
data and a "telem" binary sysfs attribute which can be used to access the
telemetry data.

Also create a PCI device id list for early telemetry hardware that require
workarounds for known issues.

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

drivers/platform/x86/Kconfig

@@ -1374,6 +1374,17 @@ config INTEL_PMT_CLASS
 	  To compile this driver as a module, choose M here: the module
 	  will be called intel_pmt_class.
 
+config INTEL_PMT_TELEMETRY
+	tristate "Intel Platform Monitoring Technology (PMT) Telemetry driver"
+	select INTEL_PMT_CLASS
+	help
+	  The Intel Platform Monitory Technology (PMT) Telemetry driver provides
+	  access to hardware telemetry metrics on devices that support the
+	  feature.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called intel_pmt_telemetry.
+
 config INTEL_PUNIT_IPC
 	tristate "Intel P-Unit IPC Driver"
 	help

drivers/platform/x86/Makefile

@@ -141,6 +141,7 @@ obj-$(CONFIG_INTEL_MID_POWER_BUTTON)	+= intel_mid_powerbtn.o
 obj-$(CONFIG_INTEL_MRFLD_PWRBTN)	+= intel_mrfld_pwrbtn.o
 obj-$(CONFIG_INTEL_PMC_CORE)		+= intel_pmc_core.o intel_pmc_core_pltdrv.o
 obj-$(CONFIG_INTEL_PMT_CLASS)		+= intel_pmt_class.o
+obj-$(CONFIG_INTEL_PMT_TELEMETRY)	+= intel_pmt_telemetry.o
 obj-$(CONFIG_INTEL_PUNIT_IPC)		+= intel_punit_ipc.o
 obj-$(CONFIG_INTEL_SCU_IPC)		+= intel_scu_ipc.o
 obj-$(CONFIG_INTEL_SCU_PCI)		+= intel_scu_pcidrv.o

drivers/platform/x86/intel_pmt_telemetry.c

@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Intel Platform Monitory Technology Telemetry driver
+ *
+ * Copyright (c) 2020, Intel Corporation.
+ * All Rights Reserved.
+ *
+ * Author: "David E. Box" <david.e.box@linux.intel.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/overflow.h>
+
+#include "intel_pmt_class.h"
+
+#define TELEM_DEV_NAME		"pmt_telemetry"
+
+#define TELEM_SIZE_OFFSET	0x0
+#define TELEM_GUID_OFFSET	0x4
+#define TELEM_BASE_OFFSET	0x8
+#define TELEM_ACCESS(v)		((v) & GENMASK(3, 0))
+/* size is in bytes */
+#define TELEM_SIZE(v)		(((v) & GENMASK(27, 12)) >> 10)
+
+/* Used by client hardware to identify a fixed telemetry entry*/
+#define TELEM_CLIENT_FIXED_BLOCK_GUID	0x10000000
+
+struct pmt_telem_priv {
+	int				num_entries;
+	struct intel_pmt_entry		entry[];
+};
+
+/*
+ * Early implementations of PMT on client platforms have some
+ * differences from the server platforms (which use the Out Of Band
+ * Management Services Module OOBMSM). This list tracks those
+ * platforms as needed to handle those differences. Newer client
+ * platforms are expected to be fully compatible with server.
+ */
+static const struct pci_device_id pmt_telem_early_client_pci_ids[] = {
+	{ PCI_VDEVICE(INTEL, 0x9a0d) }, /* TGL */
+	{ PCI_VDEVICE(INTEL, 0x467d) }, /* ADL */
+	{ }
+};
+
+static bool intel_pmt_is_early_client_hw(struct device *dev)
+{
+	struct pci_dev *parent = to_pci_dev(dev->parent);
+
+	return !!pci_match_id(pmt_telem_early_client_pci_ids, parent);
+}
+
+static bool pmt_telem_region_overlaps(struct intel_pmt_entry *entry,
+				      struct device *dev)
+{
+	u32 guid = readl(entry->disc_table + TELEM_GUID_OFFSET);
+
+	if (guid != TELEM_CLIENT_FIXED_BLOCK_GUID)
+		return false;
+
+	return intel_pmt_is_early_client_hw(dev);
+}
+
+static int pmt_telem_header_decode(struct intel_pmt_entry *entry,
+				   struct intel_pmt_header *header,
+				   struct device *dev)
+{
+	void __iomem *disc_table = entry->disc_table;
+
+	if (pmt_telem_region_overlaps(entry, dev))
+		return 1;
+
+	header->access_type = TELEM_ACCESS(readl(disc_table));
+	header->guid = readl(disc_table + TELEM_GUID_OFFSET);
+	header->base_offset = readl(disc_table + TELEM_BASE_OFFSET);
+
+	/* Size is measured in DWORDS, but accessor returns bytes */
+	header->size = TELEM_SIZE(readl(disc_table));
+
+	return 0;
+}
+
+static DEFINE_XARRAY_ALLOC(telem_array);
+static struct intel_pmt_namespace pmt_telem_ns = {
+	.name = "telem",
+	.xa = &telem_array,
+	.pmt_header_decode = pmt_telem_header_decode,
+};
+
+static int pmt_telem_remove(struct platform_device *pdev)
+{
+	struct pmt_telem_priv *priv = platform_get_drvdata(pdev);
+	int i;
+
+	for (i = 0; i < priv->num_entries; i++)
+		intel_pmt_dev_destroy(&priv->entry[i], &pmt_telem_ns);
+
+	return 0;
+}
+
+static int pmt_telem_probe(struct platform_device *pdev)
+{
+	struct pmt_telem_priv *priv;
+	size_t size;
+	int i, ret;
+
+	size = struct_size(priv, entry, pdev->num_resources);
+	priv = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, priv);
+
+	for (i = 0; i < pdev->num_resources; i++) {
+		struct intel_pmt_entry *entry = &priv->entry[i];
+
+		ret = intel_pmt_dev_create(entry, &pmt_telem_ns, pdev, i);
+		if (ret < 0)
+			goto abort_probe;
+		if (ret)
+			continue;
+
+		priv->num_entries++;
+	}
+
+	return 0;
+abort_probe:
+	pmt_telem_remove(pdev);
+	return ret;
+}
+
+static struct platform_driver pmt_telem_driver = {
+	.driver = {
+		.name   = TELEM_DEV_NAME,
+	},
+	.remove = pmt_telem_remove,
+	.probe  = pmt_telem_probe,
+};
+
+static int __init pmt_telem_init(void)
+{
+	return platform_driver_register(&pmt_telem_driver);
+}
+module_init(pmt_telem_init);
+
+static void __exit pmt_telem_exit(void)
+{
+	platform_driver_unregister(&pmt_telem_driver);
+	xa_destroy(&telem_array);
+}
+module_exit(pmt_telem_exit);
+
+MODULE_AUTHOR("David E. Box <david.e.box@linux.intel.com>");
+MODULE_DESCRIPTION("Intel PMT Telemetry driver");
+MODULE_ALIAS("platform:" TELEM_DEV_NAME);
+MODULE_LICENSE("GPL v2");