[PATCH v4 6/6] platform/x86/intel/vsec: Plumb ACPI PMT discovery tables through vsec

["David E. Box" <david.e.box@linux.intel.com>]

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Some platforms expose PMT discovery via ACPI instead of PCI BARs. Add a
generic discovery source flag and carry ACPI discovery entries alongside
the existing PCI resource path so PMT clients can consume either.

Changes:
  - Add enum intel_vsec_disc_source { _PCI, _ACPI }.
  - Extend intel_vsec_platform_info and intel_vsec_device with source enum
    and ACPI discovery table pointer/
  - When src==ACPI, skip BAR resource setup and copy the ACPI discovery
    entries into the aux device.

No user-visible behavior change yet; this only wires ACPI data through vsec
in preparation for ACPI-enumerated PMT clients.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
---
v4:
  - Use check_mul_overflow() instead of array_size() which was
    incorrectly checking for 0 anyway.

v3:
  - Re-send with all changes intended for v2 which was sent without them
    being applied.

v2:
  - Improve comment to clarify BAR resource setup doesn't apply to ACPI
    discovery
  - Add missing #include for kmemdup()
  - Use array_size() for overflow protection
    (review comments by Ilpo Järvinen)

 drivers/platform/x86/intel/vsec.c | 23 +++++++++++++++++++++++
 include/linux/intel_vsec.h        | 20 +++++++++++++++++++-
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/intel/vsec.c b/drivers/platform/x86/intel/vsec.c
index 4aeb0728b435..cdbaa0a7f199 100644
--- a/drivers/platform/x86/intel/vsec.c
+++ b/drivers/platform/x86/intel/vsec.c
@@ -24,7 +24,9 @@
 #include <linux/intel_vsec.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/overflow.h>
 #include <linux/pci.h>
+#include <linux/string.h>
 #include <linux/types.h>
 
 #define PMT_XA_START			0
@@ -109,6 +111,7 @@ static void intel_vsec_dev_release(struct device *dev)
 
 	ida_free(intel_vsec_dev->ida, intel_vsec_dev->auxdev.id);
 
+	kfree(intel_vsec_dev->acpi_disc);
 	kfree(intel_vsec_dev->resource);
 	kfree(intel_vsec_dev);
 }
@@ -320,6 +323,13 @@ static int intel_vsec_add_dev(struct device *dev, struct intel_vsec_header *head
 	 * auxiliary device driver.
 	 */
 	for (i = 0, tmp = res; i < header->num_entries; i++, tmp++) {
+		/*
+		 * Skip resource mapping check for ACPI-based discovery
+		 * since those tables are read from _DSD, not MMIO.
+		 */
+		if (info->src == INTEL_VSEC_DISC_ACPI)
+			break;
+
 		tmp->start = base_addr + header->offset + i * (header->entry_size * sizeof(u32));
 		tmp->end = tmp->start + (header->entry_size * sizeof(u32)) - 1;
 		tmp->flags = IORESOURCE_MEM;
@@ -338,6 +348,19 @@ static int intel_vsec_add_dev(struct device *dev, struct intel_vsec_header *head
 	intel_vsec_dev->base_addr = info->base_addr;
 	intel_vsec_dev->priv_data = info->priv_data;
 	intel_vsec_dev->cap_id = cap_id;
+	intel_vsec_dev->src = info->src;
+
+	if (info->src == INTEL_VSEC_DISC_ACPI) {
+		size_t bytes;
+
+		if (check_mul_overflow(intel_vsec_dev->num_resources,
+			sizeof(*info->acpi_disc), &bytes))
+			return -EOVERFLOW;
+
+		intel_vsec_dev->acpi_disc = kmemdup(info->acpi_disc, bytes, GFP_KERNEL);
+		if (!intel_vsec_dev->acpi_disc)
+			return -ENOMEM;
+	}
 
 	if (header->id == VSEC_ID_SDSI)
 		intel_vsec_dev->ida = &intel_vsec_sdsi_ida;
diff --git a/include/linux/intel_vsec.h b/include/linux/intel_vsec.h
index 4eecb2a6bac4..1fe5665a9d02 100644
--- a/include/linux/intel_vsec.h
+++ b/include/linux/intel_vsec.h
@@ -33,6 +33,11 @@ struct device;
 struct pci_dev;
 struct resource;
 
+enum intel_vsec_disc_source {
+	INTEL_VSEC_DISC_PCI,	/* PCI, default */
+	INTEL_VSEC_DISC_ACPI,	/* ACPI */
+};
+
 enum intel_vsec_id {
 	VSEC_ID_TELEMETRY	= 2,
 	VSEC_ID_WATCHER		= 3,
@@ -103,6 +108,10 @@ struct vsec_feature_dependency {
  * @parent:    parent device in the auxbus chain
  * @headers:   list of headers to define the PMT client devices to create
  * @deps:      array of feature dependencies
+ * @acpi_disc: ACPI discovery tables, each entry is two QWORDs
+ *             in little-endian format as defined by the PMT ACPI spec.
+ *             Valid only when @provider == INTEL_VSEC_DISC_ACPI.
+ * @src:       source of discovery table data
  * @priv_data: private data, usable by parent devices, currently a callback
  * @caps:      bitmask of PMT capabilities for the given headers
  * @quirks:    bitmask of VSEC device quirks
@@ -113,6 +122,8 @@ struct intel_vsec_platform_info {
 	struct device *parent;
 	struct intel_vsec_header **headers;
 	const struct vsec_feature_dependency *deps;
+	u32 (*acpi_disc)[4];
+	enum intel_vsec_disc_source src;
 	void *priv_data;
 	unsigned long caps;
 	unsigned long quirks;
@@ -124,7 +135,12 @@ struct intel_vsec_platform_info {
  * struct intel_vsec_device - Auxbus specific device information
  * @auxdev:        auxbus device struct for auxbus access
  * @dev:           struct device associated with the device
- * @resource:      any resources shared by the parent
+ * @resource:      PCI discovery resources (BAR windows), one per discovery
+ *                 instance. Valid only when @src == INTEL_VSEC_DISC_PCI
+ * @acpi_disc:     ACPI discovery tables, each entry is two QWORDs
+ *                 in little-endian format as defined by the PMT ACPI spec.
+ *                 Valid only when @src == INTEL_VSEC_DISC_ACPI.
+ * @src:           source of discovery table data
  * @ida:           id reference
  * @num_resources: number of resources
  * @id:            xarray id
@@ -138,6 +154,8 @@ struct intel_vsec_device {
 	struct auxiliary_device auxdev;
 	struct device *dev;
 	struct resource *resource;
+	u32 (*acpi_disc)[4];
+	enum intel_vsec_disc_source src;
 	struct ida *ida;
 	int num_resources;
 	int id; /* xa */
-- 
2.43.0