[PATCH V2 06/17] platform/x86/intel/pmt: Unify header fetch and add ACPI source

David E. Box
2026-03-25T01:48:29Z

Allow the PMT class to read discovery headers from either PCI MMIO or
ACPI-provided entries, depending on the discovery source. The new
source-aware fetch helper retrieves the first two QWORDs for both paths
while keeping the mapped discovery table available for users such as
crashlog.

Split intel_pmt_populate_entry() into source-specific resolvers:
- pmt_resolve_access_pci(): handles both ACCESS_LOCAL and ACCESS_BARID
for PCI-backed devices and sets entry->pcidev. Same existing
functionality.
- pmt_resolve_access_acpi(): handles only ACCESS_BARID for ACPI-backed
devices, rejecting ACCESS_LOCAL which has no valid semantics without
a physical discovery resource.

This maintains existing PCI behavior and makes no functional changes
for PCI devices.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
---

V2 changes:
- In pmt_resolve_access_acpi(), moved dev_err() call to single line
instead of split across two lines
- Restructured error handling in intel_pmt_populate_entry(), moving error
returns from after switch/case into each case statement for better
readability
- Addressed Ilpo's feedback on error message formatting and error
handling patterns

drivers/platform/x86/intel/pmt/class.c | 123 +++++++++++++++++++++++--
1 file changed, 114 insertions(+), 9 deletions(-)

diff --git a/drivers/platform/x86/intel/pmt/class.c b/drivers/platform/x86/intel/pmt/class.c
index 3fcea6a6e763..64678f55a20e 100644
--- a/drivers/platform/x86/intel/pmt/class.c
+++ b/drivers/platform/x86/intel/pmt/class.c
@@ -205,9 +205,9 @@ struct class intel_pmt_class = {
};
EXPORT_SYMBOL_GPL(intel_pmt_class);

-static int intel_pmt_populate_entry(struct intel_pmt_entry *entry,
- struct intel_vsec_device *ivdev,
- int idx)
+static int pmt_resolve_access_pci(struct intel_pmt_entry *entry,
+ struct intel_vsec_device *ivdev,
+ int idx)
{
struct pci_dev *pci_dev = to_pci_dev(ivdev->dev);
struct device *dev = &ivdev->auxdev.dev;
@@ -287,6 +287,81 @@ static int intel_pmt_populate_entry(struct intel_pmt_entry *entry,
}

entry->pcidev = pci_dev;
+
+ return 0;
+}
+
+static int pmt_resolve_access_acpi(struct intel_pmt_entry *entry,
+ struct intel_vsec_device *ivdev)
+{
+ struct pci_dev *pci_dev = NULL;
+ struct device *dev = &ivdev->auxdev.dev;
+ struct intel_pmt_header *header = &entry->header;
+ u8 bir;
+
+ if (dev_is_pci(ivdev->dev))
+ pci_dev = to_pci_dev(ivdev->dev);
+
+ /*
+ * The base offset should always be 8 byte aligned.
+ *
+ * For non-local access types the lower 3 bits of base offset
+ * contains the index of the base address register where the
+ * telemetry can be found.
+ */
+ bir = GET_BIR(header->base_offset);
+
+ switch (header->access_type) {
+ case ACCESS_BARID:
+ /* ACPI platform drivers use base_addr */
+ if (ivdev->base_addr) {
+ entry->base_addr = ivdev->base_addr +
+ GET_ADDRESS(header->base_offset);
+ break;
+ }
+
+ /* If base_addr is not provided, then this is an ACPI companion device */
+ if (!pci_dev) {
+ dev_err(dev, "ACCESS_BARID requires PCI BAR resources or base_addr\n");
+ return -EINVAL;
+ }
+
+ entry->base_addr = pci_resource_start(pci_dev, bir) +
+ GET_ADDRESS(header->base_offset);
+ break;
+ default:
+ dev_err(dev, "Unsupported access type %d for ACPI based PMT\n",
+ header->access_type);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int intel_pmt_populate_entry(struct intel_pmt_entry *entry,
+ struct intel_vsec_device *ivdev,
+ int idx)
+{
+ struct intel_pmt_header *header = &entry->header;
+ struct device *dev = &ivdev->auxdev.dev;
+ int ret;
+
+ switch (ivdev->src) {
+ case INTEL_VSEC_DISC_PCI:
+ ret = pmt_resolve_access_pci(entry, ivdev, idx);
+ if (ret)
+ return ret;
+ break;
+ case INTEL_VSEC_DISC_ACPI:
+ ret = pmt_resolve_access_acpi(entry, ivdev);
+ if (ret)
+ return ret;
+ break;
+ default:
+ dev_err(dev, "Unknown discovery source: %d\n", ivdev->src);
+ return -EINVAL;
+ }
+
entry->guid = header->guid;
entry->size = header->size;
entry->cb = ivdev->priv_data;
@@ -371,18 +446,48 @@ static int intel_pmt_dev_register(struct intel_pmt_entry *entry,
return ret;
}

+static int pmt_get_headers(struct intel_vsec_device *ivdev, int idx,
+ struct intel_pmt_entry *entry, u64 headers[2])
+{
+ struct device *dev = &ivdev->auxdev.dev;
+
+ switch (ivdev->src) {
+ case INTEL_VSEC_DISC_PCI: {
+ void __iomem *disc_table;
+
+ disc_table = devm_ioremap_resource(dev, &ivdev->resource[idx]);
+ if (IS_ERR(disc_table))
+ return PTR_ERR(disc_table);
+
+ memcpy_fromio(headers, disc_table, 2 * sizeof(u64));
+
+ /* Used by crashlog driver */
+ entry->disc_table = disc_table;
+
+ return 0;
+ }
+ case INTEL_VSEC_DISC_ACPI:
+ memcpy(headers, &ivdev->acpi_disc[idx][0], 2 * sizeof(u64));
+
+ return 0;
+ default:
+ dev_err(dev, "Unknown discovery source type: %d\n", ivdev->src);
+ break;
+ }
+
+ return -EINVAL;
+}
+
static int pmt_read_header(struct intel_vsec_device *ivdev, int idx,
struct intel_pmt_entry *entry)
{
struct intel_pmt_header *header = &entry->header;
- struct device *dev = &ivdev->auxdev.dev;
u64 headers[2];
+ int ret;

- entry->disc_table = devm_ioremap_resource(dev, &ivdev->resource[idx]);
- if (IS_ERR(entry->disc_table))
- return PTR_ERR(entry->disc_table);
-
- memcpy_fromio(headers, entry->disc_table, 2 * sizeof(u64));
+ ret = pmt_get_headers(ivdev, idx, entry, headers);
+ if (ret)
+ return ret;

header->access_type = FIELD_GET(PMT_ACCESS_TYPE, headers[0]);
header->telem_type = FIELD_GET(PMT_TELEM_TYPE, headers[0]);
--
2.43.0