[PATCH V6 10/20] platform/x86/intel/pmt: telemetry: Export API to read telemetry

David E. Box
2023-11-29T22:22:32Z

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>
---
V6 - No change

V5 - No change

V4 - No change

V3 - Add comment for mutex lock
- Fix multiline comments
- Fix line lengths
- Fix space/tab inconsistences in header doc

V2 - Add explanation of PMT_XA_START change in changelog
- change return and argument type of pmt_telem_get_next_endpoint() to
unsigned long
- style fixes

drivers/platform/x86/intel/pmt/class.c | 21 ++-
drivers/platform/x86/intel/pmt/class.h | 14 ++
drivers/platform/x86/intel/pmt/telemetry.c | 191 ++++++++++++++++++++-
drivers/platform/x86/intel/pmt/telemetry.h | 126 ++++++++++++++
4 files changed, 344 insertions(+), 8 deletions(-)
create mode 100644 drivers/platform/x86/intel/pmt/telemetry.h

diff --git a/drivers/platform/x86/intel/pmt/class.c b/drivers/platform/x86/intel/pmt/class.c
index 142a24e3727d..4b53940a64e2 100644
--- a/drivers/platform/x86/intel/pmt/class.c
+++ b/drivers/platform/x86/intel/pmt/class.c
@@ -17,7 +17,7 @@
#include "../vsec.h"
#include "class.h"

-#define PMT_XA_START 0
+#define PMT_XA_START 1
#define PMT_XA_MAX INT_MAX
#define PMT_XA_LIMIT XA_LIMIT(PMT_XA_START, PMT_XA_MAX)
#define GUID_SPR_PUNIT 0x9956f43f
@@ -247,6 +247,7 @@ static int intel_pmt_dev_register(struct intel_pmt_entry *entry,
struct intel_pmt_namespace *ns,
struct device *parent)
{
+ struct intel_vsec_device *ivdev = dev_to_ivdev(parent);
struct resource res = {0};
struct device *dev;
int ret;
@@ -270,7 +271,7 @@ static int intel_pmt_dev_register(struct intel_pmt_entry *entry,
if (ns->attr_grp) {
ret = sysfs_create_group(entry->kobj, ns->attr_grp);
if (ret)
- goto fail_sysfs;
+ goto fail_sysfs_create_group;
}

/* if size is 0 assume no data buffer, so no file needed */
@@ -295,13 +296,23 @@ static int intel_pmt_dev_register(struct intel_pmt_entry *entry,
entry->pmt_bin_attr.size = entry->size;

ret = sysfs_create_bin_file(&dev->kobj, &entry->pmt_bin_attr);
- if (!ret)
- return 0;
+ if (ret)
+ goto fail_ioremap;

+ if (ns->pmt_add_endpoint) {
+ ret = ns->pmt_add_endpoint(entry, ivdev->pcidev);
+ if (ret)
+ goto fail_add_endpoint;
+ }
+
+ return 0;
+
+fail_add_endpoint:
+ sysfs_remove_bin_file(entry->kobj, &entry->pmt_bin_attr);
fail_ioremap:
if (ns->attr_grp)
sysfs_remove_group(entry->kobj, ns->attr_grp);
-fail_sysfs:
+fail_sysfs_create_group:
device_unregister(dev);
fail_dev_create:
xa_erase(ns->xa, entry->devid);
diff --git a/drivers/platform/x86/intel/pmt/class.h b/drivers/platform/x86/intel/pmt/class.h
index e477a19f6700..d23c63b73ab7 100644
--- a/drivers/platform/x86/intel/pmt/class.h
+++ b/drivers/platform/x86/intel/pmt/class.h
@@ -9,6 +9,7 @@
#include <linux/io.h>

#include "../vsec.h"
+#include "telemetry.h"

/* PMT access types */
#define ACCESS_BARID 2
@@ -18,6 +19,16 @@
#define GET_BIR(v) ((v) & GENMASK(2, 0))
#define GET_ADDRESS(v) ((v) & GENMASK(31, 3))

+struct pci_dev;
+
+struct telem_endpoint {
+ struct pci_dev *pcidev;
+ struct telem_header header;
+ void __iomem *base;
+ bool present;
+ struct kref kref;
+};
+
struct intel_pmt_header {
u32 base_offset;
u32 size;
@@ -26,6 +37,7 @@ struct intel_pmt_header {
};

struct intel_pmt_entry {
+ struct telem_endpoint *ep;
struct intel_pmt_header header;
struct bin_attribute pmt_bin_attr;
struct kobject *kobj;
@@ -43,6 +55,8 @@ struct intel_pmt_namespace {
const struct attribute_group *attr_grp;
int (*pmt_header_decode)(struct intel_pmt_entry *entry,
struct device *dev);
+ int (*pmt_add_endpoint)(struct intel_pmt_entry *entry,
+ struct pci_dev *pdev);
};

bool intel_pmt_is_early_client_hw(struct device *dev);
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)
diff --git a/drivers/platform/x86/intel/pmt/telemetry.h b/drivers/platform/x86/intel/pmt/telemetry.h
new file mode 100644
index 000000000000..d45af5512b4e
--- /dev/null
+++ b/drivers/platform/x86/intel/pmt/telemetry.h
@@ -0,0 +1,126 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _TELEMETRY_H
+#define _TELEMETRY_H
+
+/* Telemetry types */
+#define PMT_TELEM_TELEMETRY 0
+#define PMT_TELEM_CRASHLOG 1
+
+struct telem_endpoint;
+struct pci_dev;
+
+struct telem_header {
+ u8 access_type;
+ u16 size;
+ u32 guid;
+ u32 base_offset;
+};
+
+struct telem_endpoint_info {
+ struct pci_dev *pdev;
+ struct telem_header header;
+};
+
+/**
+ * pmt_telem_get_next_endpoint() - Get next device id for a telemetry endpoint
+ * @start: starting devid to look from
+ *
+ * This functions can be used in a while loop predicate to retrieve the devid
+ * of all available telemetry endpoints. Functions pmt_telem_get_next_endpoint()
+ * and pmt_telem_register_endpoint() can be used inside of the loop to examine
+ * endpoint info and register to receive a pointer to the endpoint. The pointer
+ * is then usable in the telemetry read calls to access the telemetry data.
+ *
+ * Return:
+ * * devid - devid of the next present endpoint from start
+ * * 0 - when no more endpoints are present after start
+ */
+unsigned long pmt_telem_get_next_endpoint(unsigned long start);
+
+/**
+ * pmt_telem_register_endpoint() - Register a telemetry endpoint
+ * @devid: device id/handle of the telemetry endpoint
+ *
+ * Increments the kref usage counter for the endpoint.
+ *
+ * Return:
+ * * endpoint - On success returns pointer to the telemetry endpoint
+ * * -ENXIO - telemetry endpoint not found
+ */
+struct telem_endpoint *pmt_telem_register_endpoint(int devid);
+
+/**
+ * pmt_telem_unregister_endpoint() - Unregister a telemetry endpoint
+ * @ep: ep structure to populate.
+ *
+ * Decrements the kref usage counter for the endpoint.
+ */
+void pmt_telem_unregister_endpoint(struct telem_endpoint *ep);
+
+/**
+ * pmt_telem_get_endpoint_info() - Get info for an endpoint from its devid
+ * @devid: device id/handle of the telemetry endpoint
+ * @info: Endpoint info structure to be populated
+ *
+ * Return:
+ * * 0 - Success
+ * * -ENXIO - telemetry endpoint not found for the devid
+ * * -EINVAL - @info is NULL
+ */
+int pmt_telem_get_endpoint_info(int devid, struct telem_endpoint_info *info);
+
+/**
+ * pmt_telem_find_and_register_endpoint() - Get a telemetry endpoint from
+ * pci_dev device, guid and pos
+ * @pdev: PCI device inside the Intel vsec
+ * @guid: GUID of the telemetry space
+ * @pos: Instance of the guid
+ *
+ * Return:
+ * * endpoint - On success returns pointer to the telemetry endpoint
+ * * -ENXIO - telemetry endpoint not found
+ */
+struct telem_endpoint *pmt_telem_find_and_register_endpoint(struct pci_dev *pcidev,
+ u32 guid, u16 pos);
+
+/**
+ * pmt_telem_read() - Read qwords from counter sram using sample id
+ * @ep: Telemetry endpoint to be read
+ * @id: The beginning sample id of the metric(s) to be read
+ * @data: Allocated qword buffer
+ * @count: Number of qwords requested
+ *
+ * Callers must ensure reads are aligned. When the call returns -ENODEV,
+ * the device has been removed and callers should unregister the telemetry
+ * endpoint.
+ *
+ * Return:
+ * * 0 - Success
+ * * -ENODEV - The device is not present.
+ * * -EINVAL - The offset is out bounds
+ * * -EPIPE - The device was removed during the read. Data written
+ * but should be considered invalid.
+ */
+int pmt_telem_read(struct telem_endpoint *ep, u32 id, u64 *data, u32 count);
+
+/**
+ * pmt_telem_read32() - Read qwords from counter sram using sample id
+ * @ep: Telemetry endpoint to be read
+ * @id: The beginning sample id of the metric(s) to be read
+ * @data: Allocated dword buffer
+ * @count: Number of dwords requested
+ *
+ * Callers must ensure reads are aligned. When the call returns -ENODEV,
+ * the device has been removed and callers should unregister the telemetry
+ * endpoint.
+ *
+ * Return:
+ * * 0 - Success
+ * * -ENODEV - The device is not present.
+ * * -EINVAL - The offset is out bounds
+ * * -EPIPE - The device was removed during the read. Data written
+ * but should be considered invalid.
+ */
+int pmt_telem_read32(struct telem_endpoint *ep, u32 id, u32 *data, u32 count);
+
+#endif
--
2.34.1