platform/x86/intel/pmt: telemetry: Export API to read telemetry

Export symbols to allow access to Intel PMT Telemetry data on available
devices. Provides APIs to search, register, and read telemetry using a
kref managed pointer that serves as a handle to a telemetry endpoint.
To simplify searching for present devices, have the IDA start at 1
instead of 0 so that 0 can be used to indicate end of search.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20231129222132.2331261-11-david.e.box@linux.intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

1 files changed, 188 insertions, 3 deletions

diff --git a/drivers/platform/x86/intel/pmt/telemetry.c b/drivers/platform/x86/intel/pmt/telemetry.c
index f86080e8bebd..09258564dfc4 100644
--- a/drivers/platform/x86/intel/pmt/telemetry.c
+++ b/drivers/platform/x86/intel/pmt/telemetry.c
@@ -30,6 +30,15 @@
 /* Used by client hardware to identify a fixed telemetry entry*/
 #define TELEM_CLIENT_FIXED_BLOCK_GUID	0x10000000
 
+#define NUM_BYTES_QWORD(v)	((v) << 3)
+#define SAMPLE_ID_OFFSET(v)	((v) << 3)
+
+#define NUM_BYTES_DWORD(v)	((v) << 2)
+#define SAMPLE_ID_OFFSET32(v)	((v) << 2)
+
+/* Protects access to the xarray of telemetry endpoint handles */
+static DEFINE_MUTEX(ep_lock);
+
 enum telem_type {
 	TELEM_TYPE_PUNIT = 0,
 	TELEM_TYPE_CRASHLOG,
@@ -84,21 +93,195 @@ static int pmt_telem_header_decode(struct intel_pmt_entry *entry,
 	return 0;
 }
 
+static int pmt_telem_add_endpoint(struct intel_pmt_entry *entry,
+				  struct pci_dev *pdev)
+{
+	struct telem_endpoint *ep;
+
+	/* Endpoint lifetimes are managed by kref, not devres */
+	entry->ep = kzalloc(sizeof(*(entry->ep)), GFP_KERNEL);
+	if (!entry->ep)
+		return -ENOMEM;
+
+	ep = entry->ep;
+	ep->pcidev = pdev;
+	ep->header.access_type = entry->header.access_type;
+	ep->header.guid = entry->header.guid;
+	ep->header.base_offset = entry->header.base_offset;
+	ep->header.size = entry->header.size;
+	ep->base = entry->base;
+	ep->present = true;
+
+	kref_init(&ep->kref);
+
+	return 0;
+}
+
 static DEFINE_XARRAY_ALLOC(telem_array);
 static struct intel_pmt_namespace pmt_telem_ns = {
 	.name = "telem",
 	.xa = &telem_array,
 	.pmt_header_decode = pmt_telem_header_decode,
+	.pmt_add_endpoint = pmt_telem_add_endpoint,
 };
 
+/* Called when all users unregister and the device is removed */
+static void pmt_telem_ep_release(struct kref *kref)
+{
+	struct telem_endpoint *ep;
+
+	ep = container_of(kref, struct telem_endpoint, kref);
+	kfree(ep);
+}
+
+unsigned long pmt_telem_get_next_endpoint(unsigned long start)
+{
+	struct intel_pmt_entry *entry;
+	unsigned long found_idx;
+
+	mutex_lock(&ep_lock);
+	xa_for_each_start(&telem_array, found_idx, entry, start) {
+		/*
+		 * Return first found index after start.
+		 * 0 is not valid id.
+		 */
+		if (found_idx > start)
+			break;
+	}
+	mutex_unlock(&ep_lock);
+
+	return found_idx == start ? 0 : found_idx;
+}
+EXPORT_SYMBOL_NS_GPL(pmt_telem_get_next_endpoint, INTEL_PMT_TELEMETRY);
+
+struct telem_endpoint *pmt_telem_register_endpoint(int devid)
+{
+	struct intel_pmt_entry *entry;
+	unsigned long index = devid;
+
+	mutex_lock(&ep_lock);
+	entry = xa_find(&telem_array, &index, index, XA_PRESENT);
+	if (!entry) {
+		mutex_unlock(&ep_lock);
+		return ERR_PTR(-ENXIO);
+	}
+
+	kref_get(&entry->ep->kref);
+	mutex_unlock(&ep_lock);
+
+	return entry->ep;
+}
+EXPORT_SYMBOL_NS_GPL(pmt_telem_register_endpoint, INTEL_PMT_TELEMETRY);
+
+void pmt_telem_unregister_endpoint(struct telem_endpoint *ep)
+{
+	kref_put(&ep->kref, pmt_telem_ep_release);
+}
+EXPORT_SYMBOL_NS_GPL(pmt_telem_unregister_endpoint, INTEL_PMT_TELEMETRY);
+
+int pmt_telem_get_endpoint_info(int devid, struct telem_endpoint_info *info)
+{
+	struct intel_pmt_entry *entry;
+	unsigned long index = devid;
+	int err = 0;
+
+	if (!info)
+		return -EINVAL;
+
+	mutex_lock(&ep_lock);
+	entry = xa_find(&telem_array, &index, index, XA_PRESENT);
+	if (!entry) {
+		err = -ENXIO;
+		goto unlock;
+	}
+
+	info->pdev = entry->ep->pcidev;
+	info->header = entry->ep->header;
+
+unlock:
+	mutex_unlock(&ep_lock);
+	return err;
+
+}
+EXPORT_SYMBOL_NS_GPL(pmt_telem_get_endpoint_info, INTEL_PMT_TELEMETRY);
+
+int pmt_telem_read(struct telem_endpoint *ep, u32 id, u64 *data, u32 count)
+{
+	u32 offset, size;
+
+	if (!ep->present)
+		return -ENODEV;
+
+	offset = SAMPLE_ID_OFFSET(id);
+	size = ep->header.size;
+
+	if (offset + NUM_BYTES_QWORD(count) > size)
+		return -EINVAL;
+
+	memcpy_fromio(data, ep->base + offset, NUM_BYTES_QWORD(count));
+
+	return ep->present ? 0 : -EPIPE;
+}
+EXPORT_SYMBOL_NS_GPL(pmt_telem_read, INTEL_PMT_TELEMETRY);
+
+int pmt_telem_read32(struct telem_endpoint *ep, u32 id, u32 *data, u32 count)
+{
+	u32 offset, size;
+
+	if (!ep->present)
+		return -ENODEV;
+
+	offset = SAMPLE_ID_OFFSET32(id);
+	size = ep->header.size;
+
+	if (offset + NUM_BYTES_DWORD(count) > size)
+		return -EINVAL;
+
+	memcpy_fromio(data, ep->base + offset, NUM_BYTES_DWORD(count));
+
+	return ep->present ? 0 : -EPIPE;
+}
+EXPORT_SYMBOL_NS_GPL(pmt_telem_read32, INTEL_PMT_TELEMETRY);
+
+struct telem_endpoint *
+pmt_telem_find_and_register_endpoint(struct pci_dev *pcidev, u32 guid, u16 pos)
+{
+	int devid = 0;
+	int inst = 0;
+	int err = 0;
+
+	while ((devid = pmt_telem_get_next_endpoint(devid))) {
+		struct telem_endpoint_info ep_info;
+
+		err = pmt_telem_get_endpoint_info(devid, &ep_info);
+		if (err)
+			return ERR_PTR(err);
+
+		if (ep_info.header.guid == guid && ep_info.pdev == pcidev) {
+			if (inst == pos)
+				return pmt_telem_register_endpoint(devid);
+			++inst;
+		}
+	}
+
+	return ERR_PTR(-ENXIO);
+}
+EXPORT_SYMBOL_NS_GPL(pmt_telem_find_and_register_endpoint, INTEL_PMT_TELEMETRY);
+
 static void pmt_telem_remove(struct auxiliary_device *auxdev)
 {
 	struct pmt_telem_priv *priv = auxiliary_get_drvdata(auxdev);
 	int i;
 
-	for (i = 0; i < priv->num_entries; i++)
-		intel_pmt_dev_destroy(&priv->entry[i], &pmt_telem_ns);
-}
+	mutex_lock(&ep_lock);
+	for (i = 0; i < priv->num_entries; i++) {
+		struct intel_pmt_entry *entry = &priv->entry[i];
+
+		kref_put(&entry->ep->kref, pmt_telem_ep_release);
+		intel_pmt_dev_destroy(entry, &pmt_telem_ns);
+	}
+	mutex_unlock(&ep_lock);
+};
 
 static int pmt_telem_probe(struct auxiliary_device *auxdev, const struct auxiliary_device_id *id)
 {
@@ -117,7 +300,9 @@ static int pmt_telem_probe(struct auxiliary_device *auxdev, const struct auxilia
 	for (i = 0; i < intel_vsec_dev->num_resources; i++) {
 		struct intel_pmt_entry *entry = &priv->entry[priv->num_entries];
 
+		mutex_lock(&ep_lock);
 		ret = intel_pmt_dev_create(entry, &pmt_telem_ns, intel_vsec_dev, i);
+		mutex_unlock(&ep_lock);
 		if (ret < 0)
 			goto abort_probe;
 		if (ret)