platform/x86/intel/pmc: Add ACPI PWRM telemetry driver for Nova Lake S

Add an ACPI-based PMC PWRM telemetry driver for Nova Lake S. The driver
locates PMT discovery data in _DSD under the Intel VSEC UUID, parses it,
and registers telemetry regions with the PMT/VSEC framework so PMC
telemetry is exposed via existing PMT interfaces.

Export pmc_parse_telem_dsd() and pmc_find_telem_guid() to support ACPI
discovery in other PMC drivers (e.g., ssram_telemetry) without duplicating
ACPI parsing logic. Also export acpi_disc_t typedef from core.h for callers
to properly declare discovery table arrays.

Selected by INTEL_PMC_CORE. Existing PCI functionality is preserved.

Assisted-by: GitHub-Copilot:claude-opus-4.7
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Link: https://patch.msgid.link/09b8211d8a5a79fa019ee2397137a6a43cf19430.1781294741.git.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>

drivers/platform/x86/intel/pmc/Kconfig

@@ -9,6 +9,7 @@ config INTEL_PMC_CORE
 	depends on ACPI
 	depends on INTEL_PMT_TELEMETRY
 	select INTEL_PMC_SSRAM_TELEMETRY
+	select INTEL_PMC_PWRM_TELEMETRY
 	help
 	  The Intel Platform Controller Hub for Intel Core SoCs provides access
 	  to Power Management Controller registers via various interfaces. This
@@ -39,3 +40,16 @@ config INTEL_PMC_SSRAM_TELEMETRY
 	  (including sysfs).
 
 	  This option is selected by INTEL_PMC_CORE.
+
+config INTEL_PMC_PWRM_TELEMETRY
+	tristate
+	help
+	  This driver discovers PMC PWRM telemetry regions described in ACPI
+	  _DSD and registers them with the Intel VSEC framework as Intel PMT
+	  telemetry devices.
+
+	  It validates the ACPI discovery data and publishes the discovered
+	  regions so they can be accessed through the Intel PMT telemetry
+	  interfaces (including sysfs).
+
+	  This option is selected by INTEL_PMC_CORE.

drivers/platform/x86/intel/pmc/Makefile

@@ -13,3 +13,5 @@ obj-$(CONFIG_INTEL_PMC_CORE)		+= intel_pmc_core_pltdrv.o
 # Intel PMC SSRAM driver
 intel_pmc_ssram_telemetry-y		+= ssram_telemetry.o
 obj-$(CONFIG_INTEL_PMC_SSRAM_TELEMETRY)	+= intel_pmc_ssram_telemetry.o
+intel_pmc_pwrm_telemetry-y		+= pwrm_telemetry.o
+obj-$(CONFIG_INTEL_PMC_PWRM_TELEMETRY)	+= intel_pmc_pwrm_telemetry.o

drivers/platform/x86/intel/pmc/core.h

@@ -14,10 +14,15 @@
 
 #include <linux/acpi.h>
 #include <linux/bits.h>
+#include <linux/cleanup.h>
+#include <linux/intel_vsec.h>
 #include <linux/platform_device.h>
+#include <linux/uuid.h>
 
 struct telem_endpoint;
 
+DEFINE_FREE(pmc_acpi_free, void *, if (_T) ACPI_FREE(_T))
+
 #define SLP_S0_RES_COUNTER_MASK			GENMASK(31, 0)
 
 #define PMC_BASE_ADDR_DEFAULT			0xFE000000
@@ -622,6 +627,8 @@ int pmc_core_pmt_get_blk_sub_req(struct pmc_dev *pmcdev, struct pmc *pmc,
 extern const struct file_operations pmc_core_substate_req_regs_fops;
 extern const struct file_operations pmc_core_substate_blk_req_fops;
 
+extern const guid_t intel_vsec_guid;
+
 #define pmc_for_each_mode(mode, pmc)						\
 	for (unsigned int __i = 0, __cond;					\
 	     __cond = __i < (pmc)->num_lpm_modes,				\
@@ -643,4 +650,13 @@ static const struct file_operations __name ## _fops = {			\
 	.release	= single_release,				\
 }
 
+struct intel_vsec_header;
+union acpi_object;
+
+/* Avoid checkpatch warning */
+typedef u32 (*acpi_disc_t)[PMT_DISC_DWORDS];
+
+acpi_disc_t pmc_parse_telem_dsd(union acpi_object *obj,
+				struct intel_vsec_header *header);
+union acpi_object *pmc_find_telem_guid(union acpi_object *dsd);
 #endif /* PMC_CORE_H */

drivers/platform/x86/intel/pmc/pwrm_telemetry.c

@@ -0,0 +1,216 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Intel PMC PWRM ACPI driver
+ *
+ * Copyright (C) 2025, Intel Corporation
+ */
+
+#include <linux/acpi.h>
+#include <linux/bits.h>
+#include <linux/bitfield.h>
+#include <linux/cleanup.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/intel_vsec.h>
+#include <linux/limits.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/resource.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/uuid.h>
+
+#include "core.h"
+
+#define ENTRY_LEN		5
+
+/* DWORD2 */
+#define DVSEC_ID_MASK		GENMASK(15, 0)
+#define NUM_ENTRIES_MASK	GENMASK(23, 16)
+#define ENTRY_SIZE_MASK		GENMASK(31, 24)
+
+/* DWORD3 */
+#define TBIR_MASK		GENMASK(2, 0)
+#define DISC_TBL_OFF_MASK	GENMASK(31, 3)
+
+const guid_t intel_vsec_guid =
+	GUID_INIT(0x294903fb, 0x634d, 0x4fc7, 0xaf, 0x1f, 0x0f, 0xb9,
+		  0x56, 0xb0, 0x4f, 0xc1);
+
+static bool is_valid_entry(union acpi_object *pkg)
+{
+	int i;
+
+	if (!pkg || pkg->type != ACPI_TYPE_PACKAGE || pkg->package.count != ENTRY_LEN)
+		return false;
+
+	if (pkg->package.elements[0].type != ACPI_TYPE_STRING)
+		return false;
+
+	for (i = 1; i < ENTRY_LEN; i++)
+		if (pkg->package.elements[i].type != ACPI_TYPE_INTEGER)
+			return false;
+
+	return true;
+}
+
+acpi_disc_t pmc_parse_telem_dsd(union acpi_object *obj,
+			struct intel_vsec_header *header)
+{
+	union acpi_object *vsec_pkg;
+	union acpi_object *disc_pkg;
+	u64 hdr0, hdr1;
+	int num_regions;
+	int i;
+
+	if (!header)
+		return ERR_PTR(-EINVAL);
+
+	if (!obj || obj->type != ACPI_TYPE_PACKAGE || obj->package.count != 2)
+		return ERR_PTR(-EINVAL);
+
+	/* First Package is DVSEC info */
+	vsec_pkg = &obj->package.elements[0];
+	if (!is_valid_entry(vsec_pkg))
+		return ERR_PTR(-EINVAL);
+
+	hdr0 = vsec_pkg->package.elements[3].integer.value;
+	hdr1 = vsec_pkg->package.elements[4].integer.value;
+
+	header->id          = FIELD_GET(DVSEC_ID_MASK, hdr0);
+	header->num_entries = FIELD_GET(NUM_ENTRIES_MASK, hdr0);
+	header->entry_size  = FIELD_GET(ENTRY_SIZE_MASK, hdr0);
+	header->tbir        = FIELD_GET(TBIR_MASK, hdr1);
+	header->offset      = hdr1 & DISC_TBL_OFF_MASK;
+
+	/* Second Package contains the discovery tables */
+	disc_pkg = &obj->package.elements[1];
+	if (disc_pkg->type != ACPI_TYPE_PACKAGE || disc_pkg->package.count < 1)
+		return ERR_PTR(-EINVAL);
+
+	num_regions = disc_pkg->package.count;
+	if (header->num_entries != num_regions)
+		return ERR_PTR(-EINVAL);
+
+	acpi_disc_t disc __free(kfree) = kmalloc_array(num_regions, sizeof(*disc),
+						      GFP_KERNEL);
+	if (!disc)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < num_regions; i++) {
+		union acpi_object *pkg;
+		u64 value;
+		int j;
+
+		pkg = &disc_pkg->package.elements[i];
+		if (!is_valid_entry(pkg))
+			return ERR_PTR(-EINVAL);
+
+		/* Element 0 is a descriptive string; DWORD values start at index 1. */
+		for (j = 1; j < ENTRY_LEN; j++) {
+			value = pkg->package.elements[j].integer.value;
+			if (value > U32_MAX)
+				return ERR_PTR(-ERANGE);
+
+			disc[i][j - 1] = value;
+		}
+	}
+
+	return no_free_ptr(disc);
+}
+EXPORT_SYMBOL_NS_GPL(pmc_parse_telem_dsd, "INTEL_PMC_CORE");
+
+union acpi_object *pmc_find_telem_guid(union acpi_object *dsd)
+{
+	int i;
+
+	if (!dsd || dsd->type != ACPI_TYPE_PACKAGE)
+		return NULL;
+
+	for (i = 0; i + 1 < dsd->package.count; i += 2) {
+		union acpi_object *uuid_obj, *data_obj;
+		guid_t uuid;
+
+		uuid_obj = &dsd->package.elements[i];
+		data_obj = &dsd->package.elements[i + 1];
+
+		if (uuid_obj->type != ACPI_TYPE_BUFFER ||
+		    uuid_obj->buffer.length != 16)
+			continue;
+
+		memcpy(&uuid, uuid_obj->buffer.pointer, 16);
+		if (guid_equal(&uuid, &intel_vsec_guid))
+			return data_obj;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_NS_GPL(pmc_find_telem_guid, "INTEL_PMC_CORE");
+
+static int pmc_pwrm_acpi_probe(struct platform_device *pdev)
+{
+	struct intel_vsec_header header;
+	struct intel_vsec_header *headers[2] = { &header, NULL };
+	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
+	struct intel_vsec_platform_info info = { };
+	struct device *dev = &pdev->dev;
+	union acpi_object *dsd;
+	struct resource *res;
+	acpi_handle handle;
+	acpi_status status;
+
+	handle = ACPI_HANDLE(&pdev->dev);
+	if (!handle)
+		return -ENODEV;
+
+	status = acpi_evaluate_object(handle, "_DSD", NULL, &buf);
+	if (ACPI_FAILURE(status)) {
+		return dev_err_probe(dev, -ENODEV, "Could not evaluate _DSD: %s\n",
+				     acpi_format_exception(status));
+	}
+
+	void *dsd_buf __free(pmc_acpi_free) = buf.pointer;
+
+	dsd = pmc_find_telem_guid(dsd_buf);
+	if (!dsd)
+		return -ENODEV;
+
+	acpi_disc_t acpi_disc __free(kfree) = pmc_parse_telem_dsd(dsd, &header);
+	if (IS_ERR(acpi_disc))
+		return PTR_ERR(acpi_disc);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, header.tbir);
+	if (!res)
+		return -EINVAL;
+
+	info.headers = headers;
+	info.caps = VSEC_CAP_TELEMETRY;
+	info.acpi_disc = acpi_disc;
+	info.src = INTEL_VSEC_DISC_ACPI;
+	info.base_addr = res->start;
+
+	return intel_vsec_register(&pdev->dev, &info);
+}
+
+static const struct acpi_device_id pmc_pwrm_acpi_ids[] = {
+	{ "INTC1122", 0 }, /* Nova Lake */
+	{ "INTC1129", 0 }, /* Nova Lake */
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, pmc_pwrm_acpi_ids);
+
+static struct platform_driver pmc_pwrm_acpi_driver = {
+	.probe = pmc_pwrm_acpi_probe,
+	.driver = {
+		.name = "intel_pmc_pwrm_acpi",
+		.acpi_match_table = ACPI_PTR(pmc_pwrm_acpi_ids),
+	},
+};
+module_platform_driver(pmc_pwrm_acpi_driver);
+
+MODULE_AUTHOR("David E. Box <david.e.box@linux.intel.com>");
+MODULE_DESCRIPTION("Intel PMC PWRM ACPI driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("INTEL_VSEC");