[PATCH V3 08/16] platform/x86/intel/pmc: Add ACPI PWRM telemetry driver for Nova Lake S

David E. Box
2026-05-01T23:11:06Z

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.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
---
V3 changes:
- Updated pmc_parse_telem_dsd() in pwrm_telemetry.c to use acpi_disc_t
in the function return type for consistency with the exported typedef
- Moved acpi_disc_t allocation to the allocation site with cleanup
annotation (__free(kfree)), as now specified by cleanup.h
- Style, readability and cleanup-path refinement based on review
feedback

V2 changes:
- Added explicit <linux/uuid.h> include for guid_t type availability in
core.h
- Added explicit <linux/bits.h> include in pwrm_telemetry.c for GENMASK()
- Added <linux/cleanup.h> and converted goto based cleanup to __free()
attributes per Ilpo's feedback
- Combined u64 hdr0 and u64 hdr1 into single declaration
- Converted pmc_parse_telem_dsd() to return acpi_disc directly with
ERR_PTR() for failures
- Added braces around _DSD evaluation failure path

drivers/platform/x86/intel/pmc/Kconfig | 14 ++
drivers/platform/x86/intel/pmc/Makefile | 2 +
drivers/platform/x86/intel/pmc/core.h | 15 ++
.../platform/x86/intel/pmc/pwrm_telemetry.c | 214 ++++++++++++++++++
4 files changed, 245 insertions(+)
create mode 100644 drivers/platform/x86/intel/pmc/pwrm_telemetry.c

diff --git a/drivers/platform/x86/intel/pmc/Kconfig b/drivers/platform/x86/intel/pmc/Kconfig
index 0f19dc7edcf9..937186b0b5dd 100644
--- a/drivers/platform/x86/intel/pmc/Kconfig
+++ b/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.
diff --git a/drivers/platform/x86/intel/pmc/Makefile b/drivers/platform/x86/intel/pmc/Makefile
index bb960c8721d7..fdbb768f7b09 100644
--- a/drivers/platform/x86/intel/pmc/Makefile
+++ b/drivers/platform/x86/intel/pmc/Makefile
@@ -12,3 +12,5 @@ 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
diff --git a/drivers/platform/x86/intel/pmc/core.h b/drivers/platform/x86/intel/pmc/core.h
index 118c8740ad3a..24406534c7fc 100644
--- a/drivers/platform/x86/intel/pmc/core.h
+++ b/drivers/platform/x86/intel/pmc/core.h
@@ -14,10 +14,14 @@

#include <linux/acpi.h>
#include <linux/bits.h>
+#include <linux/cleanup.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
@@ -562,6 +566,8 @@ 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, \
@@ -583,4 +589,13 @@ 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)[4];
+
+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 */
diff --git a/drivers/platform/x86/intel/pmc/pwrm_telemetry.c b/drivers/platform/x86/intel/pmc/pwrm_telemetry.c
new file mode 100644
index 000000000000..e852ee2d6d9f
--- /dev/null
+++ b/drivers/platform/x86/intel/pmc/pwrm_telemetry.c
@@ -0,0 +1,214 @@
+// 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/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;
+}
+
+u32 (*pmc_parse_telem_dsd(union acpi_object *obj,
+ struct intel_vsec_header *header))[4]
+{
+ acpi_disc_t disc __free(kfree) = NULL;
+ 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 = FIELD_GET(DISC_TBL_OFF_MASK, hdr1);
+
+ /* 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);
+
+ disc = 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 acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
+ acpi_handle handle = ACPI_HANDLE(&pdev->dev);
+ struct intel_vsec_header header;
+ struct intel_vsec_header *headers[2] = { &header, NULL };
+ struct intel_vsec_platform_info info = { };
+ struct device *dev = &pdev->dev;
+ struct resource *res;
+ union acpi_object *dsd;
+ acpi_status status;
+
+ 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");
--
2.43.0