platform/x86/intel/pmt/discovery: Get telemetry attributes

Add intel_pmt_get_features() in PMT Discovery to enable the PMT Telemetry
driver to obtain attributes of the aggregated telemetry spaces it
enumerates. The function gathers feature flags and associated data (like
the number of RMIDs) from each PMT entry, laying the groundwork for a
future kernel interface that will allow direct access to telemetry regions
based on their capabilities.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Link: https://lore.kernel.org/r/20250703022832.1302928-14-david.e.box@linux.intel.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Author: debox1

drivers/platform/x86/intel/pmt/Kconfig

@@ -18,6 +18,7 @@ config INTEL_PMT_CLASS
 config INTEL_PMT_TELEMETRY
 	tristate "Intel Platform Monitoring Technology (PMT) Telemetry driver"
 	depends on INTEL_VSEC
+	select INTEL_PMT_DISCOVERY
 	select INTEL_PMT_CLASS
 	help
 	  The Intel Platform Monitory Technology (PMT) Telemetry driver provides

drivers/platform/x86/intel/pmt/class.h

@@ -48,6 +48,7 @@ struct intel_pmt_entry {
 	struct pmt_callbacks	*cb;
 	unsigned long		base_addr;
 	size_t			size;
+	u64			feature_flags;
 	u32			guid;
 	u32			num_rmids; /* Number of Resource Monitoring IDs */
 	int			devid;
@@ -71,4 +72,10 @@ int intel_pmt_dev_create(struct intel_pmt_entry *entry,
 			 struct intel_vsec_device *dev, int idx);
 void intel_pmt_dev_destroy(struct intel_pmt_entry *entry,
 			   struct intel_pmt_namespace *ns);
+#if IS_ENABLED(CONFIG_INTEL_PMT_DISCOVERY)
+void intel_pmt_get_features(struct intel_pmt_entry *entry);
+#else
+static inline void intel_pmt_get_features(struct intel_pmt_entry *entry) {}
+#endif
+
 #endif

drivers/platform/x86/intel/pmt/discovery.c

@@ -583,6 +583,39 @@ static int pmt_features_probe(struct auxiliary_device *auxdev, const struct auxi
 	return ret;
 }
 
+static void pmt_get_features(struct intel_pmt_entry *entry, struct feature *f)
+{
+	int num_guids = f->table.header.num_guids;
+	int i;
+
+	for (i = 0; i < num_guids; i++) {
+		if (f->table.guids[i] != entry->guid)
+			continue;
+
+		entry->feature_flags |= BIT(f->id);
+
+		if (feature_layout[f->id] == LAYOUT_RMID)
+			entry->num_rmids = f->table.rmid.num_rmids;
+		else
+			entry->num_rmids = 0; /* entry is kzalloc but set anyway */
+	}
+}
+
+void intel_pmt_get_features(struct intel_pmt_entry *entry)
+{
+	struct feature *feature;
+
+	mutex_lock(&feature_list_lock);
+	list_for_each_entry(feature, &pmt_feature_list, list) {
+		if (feature->priv->parent != &entry->ep->pcidev->dev)
+			continue;
+
+		pmt_get_features(entry, feature);
+	}
+	mutex_unlock(&feature_list_lock);
+}
+EXPORT_SYMBOL_NS_GPL(intel_pmt_get_features, "INTEL_PMT");
+
 static const struct auxiliary_device_id pmt_features_id_table[] = {
 	{ .name = "intel_vsec.discovery" },
 	{}

drivers/platform/x86/intel/pmt/telemetry.c

@@ -9,11 +9,14 @@
  */
 
 #include <linux/auxiliary_bus.h>
+#include <linux/intel_pmt_features.h>
 #include <linux/intel_vsec.h>
 #include <linux/kernel.h>
+#include <linux/kref.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/slab.h>
+#include <linux/types.h>
 #include <linux/uaccess.h>
 #include <linux/overflow.h>
 
@@ -311,6 +314,8 @@ static int pmt_telem_probe(struct auxiliary_device *auxdev, const struct auxilia
 			continue;
 
 		priv->num_entries++;
+
+		intel_pmt_get_features(entry);
 	}
 
 	return 0;

include/linux/intel_vsec.h

@@ -4,6 +4,7 @@
 
 #include <linux/auxiliary_bus.h>
 #include <linux/bits.h>
+#include <linux/intel_pmt_features.h>
 
 /*
  * VSEC_CAP_UNUSED is reserved. It exists to prevent zero initialized
@@ -166,6 +167,21 @@ struct oobmsm_plat_info {
 	u8 function_number;
 };
 
+struct telemetry_region {
+	struct oobmsm_plat_info	plat_info;
+	void __iomem		*addr;
+	size_t			size;
+	u32			guid;
+	u32			num_rmids;
+};
+
+struct pmt_feature_group {
+	enum pmt_feature_id	id;
+	int			count;
+	struct kref		kref;
+	struct telemetry_region	regions[];
+};
+
 int intel_vsec_add_aux(struct pci_dev *pdev, struct device *parent,
 		       struct intel_vsec_device *intel_vsec_dev,
 		       const char *name);