Hi David,
On 14.07.2020 9:23, David E. Box wrote:
> PMT Telemetry is a capability of the Intel Platform Monitoring Technology.
> The Telemetry capability provides access to device telemetry metrics that
> provide hardware performance data to users from continuous, memory mapped,
> read-only register spaces.
>
> Register mappings are not provided by the driver. Instead, a GUID is read
> from a header for each endpoint. The GUID identifies the device and is to
> be used with an XML, provided by the vendor, to discover the available set
> of metrics and their register mapping. This allows firmware updates to
> modify the register space without needing to update the driver every time
> with new mappings. Firmware writes a new GUID in this case to specify the
> new mapping. Software tools with access to the associated XML file can
> then interpret the changes.
>
> This module manages access to all PMT Telemetry endpoints on a system,
> independent of the device exporting them. It creates a pmt_telemetry class
> to manage the devices. For each telemetry endpoint, sysfs files provide
> GUID and size information as well as a pointer to the parent device the
> telemetry came from. Software may discover the association between
> endpoints and devices by iterating through the list in sysfs, or by looking
> for the existence of the class folder under the device of interest. A
> device node of the same name allows software to then map the telemetry
> space for direct access.
>
> This patch also creates an pci device id list for early telemetry hardware
> that requires workarounds for known issues.
>
> Signed-off-by: David E. Box <david.e.box@xxxxxxxxxxxxxxx>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
> ---
> .../ABI/testing/sysfs-class-pmt_telemetry | 46 ++
> MAINTAINERS | 1 +
> drivers/platform/x86/Kconfig | 10 +
> drivers/platform/x86/Makefile | 1 +
> drivers/platform/x86/intel_pmt_telemetry.c | 454 ++++++++++++++++++
> 5 files changed, 512 insertions(+)
> create mode 100644 Documentation/ABI/testing/sysfs-class-pmt_telemetry
> create mode 100644 drivers/platform/x86/intel_pmt_telemetry.c
>
> diff --git a/Documentation/ABI/testing/sysfs-class-pmt_telemetry b/Documentation/ABI/testing/sysfs-class-pmt_telemetry
> new file mode 100644
> index 000000000000..381924549ecb
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-pmt_telemetry
> @@ -0,0 +1,46 @@
> +What: /sys/class/pmt_telemetry/
> +Date: July 2020
> +KernelVersion: 5.9
> +Contact: David Box <david.e.box@xxxxxxxxxxxxxxx>
> +Description:
> + The pmt_telemetry/ class directory contains information for
> + devices that expose hardware telemetry using Intel Platform
> + Monitoring Technology (PMT)
> +
> +What: /sys/class/pmt_telemetry/telem<x>
> +Date: July 2020
> +KernelVersion: 5.9
> +Contact: David Box <david.e.box@xxxxxxxxxxxxxxx>
> +Description:
> + The telem<x> directory contains files describing an instance of
> + a PMT telemetry device that exposes hardware telemetry. Each
> + telem<x> directory has an associated /dev/telem<x> node. This
> + node may be opened and mapped to access the telemetry space of
> + the device. The register layout of the telemetry space is
> + determined from an XML file that matches the pci device id and
> + guid for the device.
> +
> +What: /sys/class/pmt_telemetry/telem<x>/guid
> +Date: July 2020
> +KernelVersion: 5.9
> +Contact: David Box <david.e.box@xxxxxxxxxxxxxxx>
> +Description:
> + (RO) The guid for this telemetry device. The guid identifies
> + the version of the XML file for the parent device that is to
> + be used to get the register layout.
> +
> +What: /sys/class/pmt_telemetry/telem<x>/size
> +Date: July 2020
> +KernelVersion: 5.9
> +Contact: David Box <david.e.box@xxxxxxxxxxxxxxx>
> +Description:
> + (RO) The size of telemetry region in bytes that corresponds to
> + the mapping size for the /dev/telem<x> device node.
> +
> +What: /sys/class/pmt_telemetry/telem<x>/offset
> +Date: July 2020
> +KernelVersion: 5.9
> +Contact: David Box <david.e.box@xxxxxxxxxxxxxxx>
> +Description:
> + (RO) The offset of telemetry region in bytes that corresponds to
> + the mapping for the /dev/telem<x> device node.
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 2e42bf0c41ab..ebc145894abd 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8849,6 +8849,7 @@ INTEL PMT DRIVER
> M: "David E. Box" <david.e.box@xxxxxxxxxxxxxxx>
> S: Maintained
> F: drivers/mfd/intel_pmt.c
> +F: drivers/platform/x86/intel_pmt_*
>
> INTEL PRO/WIRELESS 2100, 2200BG, 2915ABG NETWORK CONNECTION SUPPORT
> M: Stanislav Yakovlev <stas.yakovlev@xxxxxxxxx>
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 0581a54cf562..5e1f7ce6e69f 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -1396,6 +1396,16 @@ config INTEL_TELEMETRY
> directly via debugfs files. Various tools may use
> this interface for SoC state monitoring.
>
> +config INTEL_PMT_TELEMETRY
> + tristate "Intel Platform Monitoring Technology (PMT) Telemetry driver"
> + help
> + The Intel Platform Monitory Technology (PMT) Telemetry driver provides
> + access to hardware telemetry metrics on devices that support the
> + feature.
> +
> + For more information, see
> + <file:Documentation/ABI/testing/sysfs-class-intel_pmt_telem>
> +
> endif # X86_PLATFORM_DEVICES
>
> config PMC_ATOM
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index 2b85852a1a87..95cd3d0be17f 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -139,6 +139,7 @@ obj-$(CONFIG_INTEL_MFLD_THERMAL) += intel_mid_thermal.o
> obj-$(CONFIG_INTEL_MID_POWER_BUTTON) += intel_mid_powerbtn.o
> obj-$(CONFIG_INTEL_MRFLD_PWRBTN) += intel_mrfld_pwrbtn.o
> obj-$(CONFIG_INTEL_PMC_CORE) += intel_pmc_core.o intel_pmc_core_pltdrv.o
> +obj-$(CONFIG_INTEL_PMT_TELEMETRY) += intel_pmt_telemetry.o
> obj-$(CONFIG_INTEL_PUNIT_IPC) += intel_punit_ipc.o
> obj-$(CONFIG_INTEL_SCU_IPC) += intel_scu_ipc.o
> obj-$(CONFIG_INTEL_SCU_PCI) += intel_scu_pcidrv.o
> diff --git a/drivers/platform/x86/intel_pmt_telemetry.c b/drivers/platform/x86/intel_pmt_telemetry.c
> new file mode 100644
> index 000000000000..e1856fc8c209
> --- /dev/null
> +++ b/drivers/platform/x86/intel_pmt_telemetry.c
> @@ -0,0 +1,454 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Intel Platform Monitory Technology Telemetry driver
> + *
> + * Copyright (c) 2020, Intel Corporation.
> + * All Rights Reserved.
> + *
> + * Author: "David E. Box" <david.e.box@xxxxxxxxxxxxxxx>
> + */
> +
> +#include <linux/bits.h>
> +#include <linux/cdev.h>
> +#include <linux/io-64-nonatomic-lo-hi.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +#include <linux/uaccess.h>
> +#include <linux/xarray.h>
> +
> +#define TELEM_DEV_NAME "pmt_telemetry"
> +
> +/* Telemetry access types */
> +#define TELEM_ACCESS_FUTURE 1
> +#define TELEM_ACCESS_BARID 2
> +#define TELEM_ACCESS_LOCAL 3
> +
> +#define TELEM_GUID_OFFSET 0x4
> +#define TELEM_BASE_OFFSET 0x8
> +#define TELEM_TBIR_MASK GENMASK(2, 0)
> +#define TELEM_ACCESS(v) ((v) & GENMASK(3, 0))
> +#define TELEM_TYPE(v) (((v) & GENMASK(7, 4)) >> 4)
> +/* size is in bytes */
> +#define TELEM_SIZE(v) (((v) & GENMASK(27, 12)) >> 10)
> +
> +#define TELEM_XA_START 0
> +#define TELEM_XA_MAX INT_MAX
> +#define TELEM_XA_LIMIT XA_LIMIT(TELEM_XA_START, TELEM_XA_MAX)
> +
> +/* Used by client hardware to identify a fixed telemetry entry*/
> +#define TELEM_CLIENT_FIXED_BLOCK_GUID 0x10000000
> +
> +static DEFINE_XARRAY_ALLOC(telem_array);
> +
> +struct pmt_telem_priv;
> +
> +struct telem_header {
> + u8 access_type;
> + u8 telem_type;
> + u16 size;
> + u32 guid;
> + u32 base_offset;
> + u8 tbir;
> +};
> +
> +struct pmt_telem_entry {
> + struct pmt_telem_priv *priv;
> + struct telem_header header;
> + struct resource *header_res;
> + unsigned long base_addr;
> + void __iomem *disc_table;
> + struct cdev cdev;
> + dev_t devt;
> + int devid;
> +};
> +
> +struct pmt_telem_priv {
> + struct pmt_telem_entry *entry;
> + int num_entries;
> + struct device *dev;
> +};
> +
> +/*
> + * devfs
> + */
> +static int pmt_telem_open(struct inode *inode, struct file *filp)
> +{
> + struct pmt_telem_priv *priv;
> + struct pmt_telem_entry *entry;
> + struct pci_driver *pci_drv;
> + struct pci_dev *pci_dev;
> +
> + if (!capable(CAP_SYS_ADMIN))
Thanks for supplying these patches.
Are there any reasons not to expose this feature to CAP_PERFMON privileged
processes too that currently have access to performance monitoring features
of the kernel without root/CAP_SYS_ADMIN credentials? This could be done by
pefmon_capable() function call starting from v5.8+.
Thanks,
Alexei
> + return -EPERM;
> +
> + entry = container_of(inode->i_cdev, struct pmt_telem_entry, cdev);
> + priv = entry->priv;
> + pci_dev = to_pci_dev(priv->dev->parent);
> +
> + pci_drv = pci_dev_driver(pci_dev);
> + if (!pci_drv)
> + return -ENODEV;
> +
> + filp->private_data = entry;
> + get_device(&pci_dev->dev);
> +
> + if (!try_module_get(pci_drv->driver.owner)) {
> + put_device(&pci_dev->dev);
> + return -ENODEV;
> + }
> +
> + return 0;
> +}
> +
> +static int pmt_telem_release(struct inode *inode, struct file *filp)
> +{
> + struct pmt_telem_entry *entry = filp->private_data;
> + struct pci_dev *pci_dev = to_pci_dev(entry->priv->dev->parent);
> + struct pci_driver *pci_drv = pci_dev_driver(pci_dev);
> +
> + put_device(&pci_dev->dev);
> + module_put(pci_drv->driver.owner);
> +
> + return 0;
> +}
> +
> +static int pmt_telem_mmap(struct file *filp, struct vm_area_struct *vma)
> +{
> + struct pmt_telem_entry *entry = filp->private_data;
> + struct pmt_telem_priv *priv;
> + unsigned long vsize = vma->vm_end - vma->vm_start;
> + unsigned long phys = entry->base_addr;
> + unsigned long pfn = PFN_DOWN(phys);
> + unsigned long psize;
> +
> + priv = entry->priv;
> + psize = (PFN_UP(entry->base_addr + entry->header.size) - pfn) *
> + PAGE_SIZE;
> + if (vsize > psize) {
> + dev_err(priv->dev, "Requested mmap size is too large\n");
> + return -EINVAL;
> + }
> +
> + if ((vma->vm_flags & VM_WRITE) || (vma->vm_flags & VM_MAYWRITE))
> + return -EPERM;
> +
> + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> +
> + if (io_remap_pfn_range(vma, vma->vm_start, pfn, vsize,
> + vma->vm_page_prot))
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static const struct file_operations pmt_telem_fops = {
> + .owner = THIS_MODULE,
> + .open = pmt_telem_open,
> + .mmap = pmt_telem_mmap,
> + .release = pmt_telem_release,
> +};
> +
> +/*
> + * sysfs
> + */
> +static ssize_t guid_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct pmt_telem_entry *entry = dev_get_drvdata(dev);
> +
> + return sprintf(buf, "0x%x\n", entry->header.guid);
> +}
> +static DEVICE_ATTR_RO(guid);
> +
> +static ssize_t size_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct pmt_telem_entry *entry = dev_get_drvdata(dev);
> +
> + /* Display buffer size in bytes */
> + return sprintf(buf, "%u\n", entry->header.size);
> +}
> +static DEVICE_ATTR_RO(size);
> +
> +static ssize_t offset_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct pmt_telem_entry *entry = dev_get_drvdata(dev);
> +
> + /* Display buffer offset in bytes */
> + return sprintf(buf, "%lu\n", offset_in_page(entry->base_addr));
> +}
> +static DEVICE_ATTR_RO(offset);
> +
> +static struct attribute *pmt_telem_attrs[] = {
> + &dev_attr_guid.attr,
> + &dev_attr_size.attr,
> + &dev_attr_offset.attr,
> + NULL
> +};
> +ATTRIBUTE_GROUPS(pmt_telem);
> +
> +struct class pmt_telem_class = {
> + .owner = THIS_MODULE,
> + .name = "pmt_telemetry",
> + .dev_groups = pmt_telem_groups,
> +};
> +
> +/*
> + * driver initialization
> + */
> +static const struct pci_device_id pmt_telem_early_client_pci_ids[] = {
> + { PCI_VDEVICE(INTEL, 0x9a0d) }, /* TGL */
> + { }
> +};
> +
> +static bool pmt_telem_is_early_client_hw(struct device *dev)
> +{
> + struct pci_dev *parent;
> +
> + parent = to_pci_dev(dev->parent);
> +
> + return !!pci_match_id(pmt_telem_early_client_pci_ids, parent);
> +}
> +
> +static int pmt_telem_create_dev(struct pmt_telem_priv *priv,
> + struct pmt_telem_entry *entry)
> +{
> + struct pci_dev *pci_dev;
> + struct device *dev;
> + int ret;
> +
> + cdev_init(&entry->cdev, &pmt_telem_fops);
> + ret = cdev_add(&entry->cdev, entry->devt, 1);
> + if (ret) {
> + dev_err(priv->dev, "Could not add char dev\n");
> + return ret;
> + }
> +
> + pci_dev = to_pci_dev(priv->dev->parent);
> + dev = device_create(&pmt_telem_class, &pci_dev->dev, entry->devt,
> + entry, "telem%d", entry->devid);
> + if (IS_ERR(dev)) {
> + dev_err(priv->dev, "Could not create device node\n");
> + cdev_del(&entry->cdev);
> + }
> +
> + return PTR_ERR_OR_ZERO(dev);
> +}
> +
> +static void pmt_telem_populate_header(void __iomem *disc_offset,
> + struct telem_header *header)
> +{
> + header->access_type = TELEM_ACCESS(readb(disc_offset));
> + header->telem_type = TELEM_TYPE(readb(disc_offset));
> + header->size = TELEM_SIZE(readl(disc_offset));
> + header->guid = readl(disc_offset + TELEM_GUID_OFFSET);
> + header->base_offset = readl(disc_offset + TELEM_BASE_OFFSET);
> +
> + /*
> + * 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.
> + */
> + header->tbir = header->base_offset & TELEM_TBIR_MASK;
> + header->base_offset ^= header->tbir;
> +}
> +
> +static int pmt_telem_add_entry(struct pmt_telem_priv *priv,
> + struct pmt_telem_entry *entry)
> +{
> + struct resource *res = entry->header_res;
> + struct pci_dev *pci_dev = to_pci_dev(priv->dev->parent);
> + int ret;
> +
> + pmt_telem_populate_header(entry->disc_table, &entry->header);
> +
> + /* Local access and BARID only for now */
> + switch (entry->header.access_type) {
> + case TELEM_ACCESS_LOCAL:
> + if (entry->header.tbir) {
> + dev_err(priv->dev,
> + "Unsupported BAR index %d for access type %d\n",
> + entry->header.tbir, entry->header.access_type);
> + return -EINVAL;
> + }
> +
> + /*
> + * For access_type LOCAL, the base address is as follows:
> + * base address = header address + header length + base offset
> + */
> + entry->base_addr = res->start + resource_size(res) +
> + entry->header.base_offset;
> + break;
> +
> + case TELEM_ACCESS_BARID:
> + entry->base_addr = pci_dev->resource[entry->header.tbir].start +
> + entry->header.base_offset;
> + break;
> +
> + default:
> + dev_err(priv->dev, "Unsupported access type %d\n",
> + entry->header.access_type);
> + return -EINVAL;
> + }
> +
> + ret = alloc_chrdev_region(&entry->devt, 0, 1, TELEM_DEV_NAME);
> + if (ret) {
> + dev_err(priv->dev,
> + "PMT telemetry chrdev_region error: %d\n", ret);
> + return ret;
> + }
> +
> + ret = xa_alloc(&telem_array, &entry->devid, entry, TELEM_XA_LIMIT,
> + GFP_KERNEL);
> + if (ret)
> + goto fail_xa_alloc;
> +
> + ret = pmt_telem_create_dev(priv, entry);
> + if (ret)
> + goto fail_create_dev;
> +
> + entry->priv = priv;
> + priv->num_entries++;
> + return 0;
> +
> +fail_create_dev:
> + xa_erase(&telem_array, entry->devid);
> +fail_xa_alloc:
> + unregister_chrdev_region(entry->devt, 1);
> +
> + return ret;
> +}
> +
> +static bool pmt_telem_region_overlaps(struct platform_device *pdev,
> + void __iomem *disc_table)
> +{
> + u32 guid;
> +
> + guid = readl(disc_table + TELEM_GUID_OFFSET);
> +
> + return guid == TELEM_CLIENT_FIXED_BLOCK_GUID;
> +}
> +
> +static void pmt_telem_remove_entries(struct pmt_telem_priv *priv)
> +{
> + int i;
> +
> + for (i = 0; i < priv->num_entries; i++) {
> + device_destroy(&pmt_telem_class, priv->entry[i].devt);
> + cdev_del(&priv->entry[i].cdev);
> + xa_erase(&telem_array, priv->entry[i].devid);
> + unregister_chrdev_region(priv->entry[i].devt, 1);
> + }
> +}
> +
> +static int pmt_telem_probe(struct platform_device *pdev)
> +{
> + struct pmt_telem_priv *priv;
> + struct pmt_telem_entry *entry;
> + bool early_hw;
> + int i;
> +
> + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + platform_set_drvdata(pdev, priv);
> + priv->dev = &pdev->dev;
> +
> + priv->entry = devm_kcalloc(&pdev->dev, pdev->num_resources,
> + sizeof(struct pmt_telem_entry), GFP_KERNEL);
> + if (!priv->entry)
> + return -ENOMEM;
> +
> + if (pmt_telem_is_early_client_hw(&pdev->dev))
> + early_hw = true;
> +
> + for (i = 0, entry = priv->entry; i < pdev->num_resources;
> + i++, entry++) {
> + int ret;
> +
> + entry->header_res = platform_get_resource(pdev, IORESOURCE_MEM,
> + i);
> + if (!entry->header_res) {
> + pmt_telem_remove_entries(priv);
> + return -ENODEV;
> + }
> +
> + entry->disc_table = devm_platform_ioremap_resource(pdev, i);
> + if (IS_ERR(entry->disc_table)) {
> + pmt_telem_remove_entries(priv);
> + return PTR_ERR(entry->disc_table);
> + }
> +
> + if (pmt_telem_region_overlaps(pdev, entry->disc_table) &&
> + early_hw)
> + continue;
> +
> + ret = pmt_telem_add_entry(priv, entry);
> + if (ret) {
> + pmt_telem_remove_entries(priv);
> + return ret;
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int pmt_telem_remove(struct platform_device *pdev)
> +{
> + struct pmt_telem_priv *priv = platform_get_drvdata(pdev);
> +
> + pmt_telem_remove_entries(priv);
> +
> + return 0;
> +}
> +
> +static const struct platform_device_id pmt_telem_table[] = {
> + {
> + .name = "pmt_telemetry",
> + },
> + {}
> +};
> +MODULE_DEVICE_TABLE(platform, pmt_telem_table);
> +
> +static struct platform_driver pmt_telem_driver = {
> + .driver = {
> + .name = TELEM_DEV_NAME,
> + },
> + .probe = pmt_telem_probe,
> + .remove = pmt_telem_remove,
> + .id_table = pmt_telem_table,
> +};
> +
> +static int __init pmt_telem_init(void)
> +{
> + int ret = class_register(&pmt_telem_class);
> +
> + if (ret)
> + return ret;
> +
> + ret = platform_driver_register(&pmt_telem_driver);
> + if (ret)
> + class_unregister(&pmt_telem_class);
> +
> + return ret;
> +}
> +module_init(pmt_telem_init);
> +
> +static void __exit pmt_telem_exit(void)
> +{
> + platform_driver_unregister(&pmt_telem_driver);
> + class_unregister(&pmt_telem_class);
> + xa_destroy(&telem_array);
> +}
> +module_exit(pmt_telem_exit);
> +
> +MODULE_AUTHOR("David E. Box <david.e.box@xxxxxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Intel PMT Telemetry driver");
> +MODULE_ALIAS("platform:" TELEM_DEV_NAME);
> +MODULE_LICENSE("GPL v2");
>
