Merge tag 'pci-v6.13-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci

Pull PCI updates from Bjorn Helgaas:
 "Enumeration:

   - Make pci_stop_dev() and pci_destroy_dev() safe so concurrent
     callers can't stop a device multiple times, even as we migrate from
     the global pci_rescan_remove_lock to finer-grained locking (Keith
     Busch)

   - Improve pci_walk_bus() implementation by making it recursive and
     moving locking up to avoid need for a 'locked' parameter (Keith
     Busch)

   - Unexport pci_walk_bus_locked(), which is only used internally by
     the PCI core (Keith Busch)

   - Detect some Thunderbolt chips that are built-in and hence
     'trustworthy' by a heuristic since the 'ExternalFacingPort' and
     'usb4-host-interface' ACPI properties are not quite enough (Esther
     Shimanovich)

  Resource management:

   - Use PCI bus addresses (not CPU addresses) in 'ranges' properties
     when building dynamic DT nodes so systems where PCI and CPU
     addresses differ work correctly (Andrea della Porta)

   - Tidy resource sizing and assignment with helpers to reduce
     redundancy (Ilpo Järvinen)

   - Improve pdev_sort_resources() 'bogus alignment' warning to be more
     specific (Ilpo Järvinen)

  Driver binding:

   - Convert driver .remove_new() callbacks to .remove() again to finish
     the conversion from returning 'int' to being 'void' (Sergio
     Paracuellos)

   - Export pcim_request_all_regions(), a managed interface to request
     all BARs (Philipp Stanner)

   - Replace pcim_iomap_regions_request_all() with
     pcim_request_all_regions(), and pcim_iomap_table()[n] with
     pcim_iomap(n), in the following drivers: ahci, crypto qat, crypto
     octeontx2, intel_th, iwlwifi, ntb idt, serial rp2, ALSA korg1212
     (Philipp Stanner)

   - Remove the now unused pcim_iomap_regions_request_all() (Philipp
     Stanner)

   - Export pcim_iounmap_region(), a managed interface to unmap and
     release a PCI BAR (Philipp Stanner)

   - Replace pcim_iomap_regions(mask) with pcim_iomap_region(n), and
     pcim_iounmap_regions(mask) with pcim_iounmap_region(n), in the
     following drivers: fpga dfl-pci, block mtip32xx, gpio-merrifield,
     cavium (Philipp Stanner)

  Error handling:

   - Add sysfs 'reset_subordinate' to reset the entire hierarchy below a
     bridge; previously Secondary Bus Reset could only be used when
     there was a single device below a bridge (Keith Busch)

   - Warn if we reset a running device where the driver didn't register
     pci_error_handlers notification callbacks (Keith Busch)

  ASPM:

   - Disable ASPM L1 before touching L1 PM Substates to follow the spec
     closer and avoid a CPU load timeout on some platforms (Ajay
     Agarwal)

   - Set devices below Intel VMD to D0 before enabling ASPM L1 Substates
     as required per spec for all L1 Substates changes (Jian-Hong Pan)

  Power management:

   - Enable starfive controller runtime PM before probing host bridge
     (Mayank Rana)

   - Enable runtime power management for host bridges (Krishna chaitanya
     chundru)

  Power control:

   - Use of_platform_device_create() instead of of_platform_populate()
     to create pwrctl platform devices so we can control it based on the
     child nodes (Manivannan Sadhasivam)

   - Create pwrctrl platform devices only if there's a relevant power
     supply property (Manivannan Sadhasivam)

   - Add device link from the pwrctl supplier to the PCI dev to ensure
     pwrctl drivers are probed before the PCI dev driver; this avoids a
     race where pwrctl could change device power state while the PCI
     driver was active (Manivannan Sadhasivam)

   - Find pwrctl device for removal with of_find_device_by_node()
     instead of searching all children of the parent (Manivannan
     Sadhasivam)

   - Rename 'pwrctl' to 'pwrctrl' to match new bandwidth controller
     ('bwctrl') and hotplug files (Bjorn Helgaas)

  Bandwidth control:

   - Add read/modify/write locking for Link Control 2, which is used to
     manage Link speed (Ilpo Järvinen)

   - Extract Link Bandwidth Management Status check into
     pcie_lbms_seen(), where it can be shared between the bandwidth
     controller and quirks that use it to help retrain failed links
     (Ilpo Järvinen)

   - Re-add Link Bandwidth notification support with updates to address
     the reasons it was previously reverted (Alexandru Gagniuc, Ilpo
     Järvinen)

   - Add pcie_set_target_speed() and related functionality so drivers
     can manage PCIe Link speed based on thermal or other constraints
     (Ilpo Järvinen)

   - Add a thermal cooling driver to throttle PCIe Links via the
     existing thermal management framework (Ilpo Järvinen)

   - Add a userspace selftest for the PCIe bandwidth controller (Ilpo
     Järvinen)

  PCI device hotplug:

   - Add hotplug controller driver for Marvell OCTEON multi-function
     device where function 0 has a management console interface to
     enable/disable and provision various personalities for the other
     functions (Shijith Thotton)

   - Retain a reference to the pci_bus for the lifetime of a pci_slot to
     avoid a use-after-free when the thunderbolt driver resets USB4 host
     routers on boot, causing hotplug remove/add of downstream docks or
     other devices (Lukas Wunner)

   - Remove unused cpcihp struct cpci_hp_controller_ops.hardware_test
     (Guilherme Giacomo Simoes)

   - Remove unused cpqphp struct ctrl_dbg.ctrl (Christophe JAILLET)

   - Use pci_bus_read_dev_vendor_id() instead of hand-coded presence
     detection in cpqphp (Ilpo Järvinen)

   - Simplify cpqphp enumeration, which is already simple-minded and
     doesn't handle devices below hot-added bridges (Ilpo Järvinen)

  Virtualization:

   - Add ACS quirk for Wangxun FF5xxx NICs, which don't advertise an ACS
     capability but do isolate functions as though PCI_ACS_RR and
     PCI_ACS_CR were set, so the functions can be in independent IOMMU
     groups (Mengyuan Lou)

  TLP Processing Hints (TPH):

   - Add and document TLP Processing Hints (TPH) support so drivers can
     enable and disable TPH and the kernel can save/restore TPH
     configuration (Wei Huang)

   - Add TPH Steering Tag support so drivers can retrieve Steering Tag
     values associated with specific CPUs via an ACPI _DSM to improve
     performance by directing DMA writes closer to their consumers (Wei
     Huang)

  Data Object Exchange (DOE):

   - Wait up to 1 second for DOE Busy bit to clear before writing a
     request to the mailbox to avoid failures if the mailbox is still
     busy from a previous transfer (Gregory Price)

  Endpoint framework:

   - Skip attempts to allocate from endpoint controller memory window if
     the requested size is larger than the window (Damien Le Moal)

   - Add and document pci_epc_mem_map() and pci_epc_mem_unmap() to
     handle controller-specific size and alignment constraints, and add
     test cases to the endpoint test driver (Damien Le Moal)

   - Implement dwc pci_epc_ops.align_addr() so pci_epc_mem_map() can
     observe DWC-specific alignment requirements (Damien Le Moal)

   - Synchronously cancel command handler work in endpoint test before
     cleaning up DMA and BARs (Damien Le Moal)

   - Respect endpoint page size in dw_pcie_ep_align_addr() (Niklas
     Cassel)

   - Use dw_pcie_ep_align_addr() in dw_pcie_ep_raise_msi_irq() and
     dw_pcie_ep_raise_msix_irq() instead of open coding the equivalent
     (Niklas Cassel)

   - Avoid NULL dereference if Modem Host Interface Endpoint lacks
     'mmio' DT property (Zhongqiu Han)

   - Release PCI domain ID of Endpoint controller parent (not controller
     itself) and before unregistering the controller, to avoid
     use-after-free (Zijun Hu)

   - Clear secondary (not primary) EPC in pci_epc_remove_epf() when
     removing the secondary controller associated with an NTB (Zijun Hu)

  Cadence PCIe controller driver:

   - Lower severity of 'phy-names' message (Bartosz Wawrzyniak)

  Freescale i.MX6 PCIe controller driver:

   - Fix suspend/resume support on i.MX6QDL, which has a hardware
     erratum that prevents use of L2 (Stefan Eichenberger)

  Intel VMD host bridge driver:

   - Add 0xb60b and 0xb06f Device IDs for client SKUs (Nirmal Patel)

  MediaTek PCIe Gen3 controller driver:

   - Update mediatek-gen3 DT binding to require the exact number of
     clocks for each SoC (Fei Shao)

   - Add support for DT 'max-link-speed' and 'num-lanes' properties to
     restrict the link speed and width (AngeloGioacchino Del Regno)

  Microchip PolarFlare PCIe controller driver:

   - Add DT and driver support for using either of the two PolarFire
     Root Ports (Conor Dooley)

  NVIDIA Tegra194 PCIe controller driver:

   - Move endpoint controller cleanups that depend on refclk from the
     host to the notifier that tells us the host has deasserted PERST#,
     when refclk should be valid (Manivannan Sadhasivam)

  Qualcomm PCIe controller driver:

   - Add qcom SAR2130P DT binding with an additional clock (Dmitry
     Baryshkov)

   - Enable MSI interrupts if 'global' IRQ is supported, since a
     previous commit unintentionally masked them (Manivannan Sadhasivam)

   - Move endpoint controller cleanups that depend on refclk from the
     host to the notifier that tells us the host has deasserted PERST#,
     when refclk should be valid (Manivannan Sadhasivam)

   - Add DT binding and driver support for IPQ9574, with Synopsys IP
     v5.80a and Qcom IP 1.27.0 (devi priya)

   - Move the OPP "operating-points-v2" table from the
     qcom,pcie-sm8450.yaml DT binding to qcom,pcie-common.yaml, where it
     can be used by other Qcom platforms (Qiang Yu)

   - Add 'global' SPI interrupt for events like link-up, link-down to
     qcom,pcie-x1e80100 DT binding so we can start enumeration when the
     link comes up (Qiang Yu)

   - Disable ASPM L0s for qcom,pcie-x1e80100 since the PHY is not tuned
     to support this (Qiang Yu)

   - Add ops_1_21_0 for SC8280X family SoC, which doesn't use the
     'iommu-map' DT property and doesn't need BDF-to-SID translation
     (Qiang Yu)

  Rockchip PCIe controller driver:

   - Define ROCKCHIP_PCIE_AT_SIZE_ALIGN to replace magic 256 endpoint
     .align value (Damien Le Moal)

   - When unmapping an endpoint window, compute the region index instead
     of searching for it, and verify that the address was mapped (Damien
     Le Moal)

   - When mapping an endpoint window, verify that the address hasn't
     been mapped already (Damien Le Moal)

   - Implement pci_epc_ops.align_addr() for rockchip-ep (Damien Le Moal)

   - Fix MSI IRQ data mapping to observe the alignment constraint, which
     fixes intermittent page faults in memcpy_toio() and memcpy_fromio()
     (Damien Le Moal)

   - Rename rockchip_pcie_parse_ep_dt() to
     rockchip_pcie_ep_get_resources() for consistency with similar DT
     interfaces (Damien Le Moal)

   - Skip the unnecessary link train in rockchip_pcie_ep_probe() and do
     it only in the endpoint start operation (Damien Le Moal)

   - Implement pci_epc_ops.stop_link() to disable link training and
     controller configuration (Damien Le Moal)

   - Attempt link training at 5 GT/s when both partners support it
     (Damien Le Moal)

   - Add a handler for PERST# signal so we can detect host-initiated
     resets and start link training after PERST# is deasserted (Damien
     Le Moal)

  Synopsys DesignWare PCIe controller driver:

   - Clear outbound address on unmap so dw_pcie_find_index() won't match
     an ATU index that was already unmapped (Damien Le Moal)

   - Use of_property_present() instead of of_property_read_bool() when
     testing for presence of non-boolean DT properties (Rob Herring)

   - Advertise 1MB size if endpoint supports Resizable BARs, which was
     inadvertently lost in v6.11 (Niklas Cassel)

  TI J721E PCIe driver:

   - Add PCIe support for J722S SoC (Siddharth Vadapalli)

   - Delay PCIE_T_PVPERL_MS (100 ms), not just PCIE_T_PERST_CLK_US (100
     us), before deasserting PERST# to ensure power and refclk are
     stable (Siddharth Vadapalli)

  TI Keystone PCIe controller driver:

   - Set the 'ti,keystone-pcie' mode so v3.65a devices work in Root
     Complex mode (Kishon Vijay Abraham I)

   - Try to avoid unrecoverable SError for attempts to issue config
     transactions when the link is down; this is racy but the best we
     can do (Kishon Vijay Abraham I)

  Miscellaneous:

   - Reorganize kerneldoc parameter names to match order in function
     signature (Julia Lawall)

   - Fix sysfs reset_method_store() memory leak (Todd Kjos)

   - Simplify pci_create_slot() (Ilpo Järvinen)

   - Fix incorrect printf format specifiers in pcitest (Luo Yifan)"

* tag 'pci-v6.13-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci: (127 commits)
  PCI: rockchip-ep: Handle PERST# signal in EP mode
  PCI: rockchip-ep: Improve link training
  PCI: rockship-ep: Implement the pci_epc_ops::stop_link() operation
  PCI: rockchip-ep: Refactor endpoint link training enable
  PCI: rockchip-ep: Refactor rockchip_pcie_ep_probe() MSI-X hiding
  PCI: rockchip-ep: Refactor rockchip_pcie_ep_probe() memory allocations
  PCI: rockchip-ep: Rename rockchip_pcie_parse_ep_dt()
  PCI: rockchip-ep: Fix MSI IRQ data mapping
  PCI: rockchip-ep: Implement the pci_epc_ops::align_addr() operation
  PCI: rockchip-ep: Improve rockchip_pcie_ep_map_addr()
  PCI: rockchip-ep: Improve rockchip_pcie_ep_unmap_addr()
  PCI: rockchip-ep: Use a macro to define EP controller .align feature
  PCI: rockchip-ep: Fix address translation unit programming
  PCI/pwrctrl: Rename pwrctrl functions and structures
  PCI/pwrctrl: Rename pwrctl files to pwrctrl
  PCI/pwrctl: Remove pwrctl device without iterating over all children of pwrctl parent
  PCI/pwrctl: Ensure that pwrctl drivers are probed before PCI client drivers
  PCI/pwrctl: Create pwrctl device only if at least one power supply is present
  PCI/pwrctl: Use of_platform_device_create() to create pwrctl devices
  tools: PCI: Fix incorrect printf format specifiers
  ...

1 files changed, 547 insertions, 0 deletions

diff --git a/drivers/pci/tph.c b/drivers/pci/tph.c
new file mode 100644
index 000000000000..1e604fbbda65
--- /dev/null
+++ b/drivers/pci/tph.c
@@ -0,0 +1,547 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * TPH (TLP Processing Hints) support
+ *
+ * Copyright (C) 2024 Advanced Micro Devices, Inc.
+ *     Eric Van Tassell <Eric.VanTassell@amd.com>
+ *     Wei Huang <wei.huang2@amd.com>
+ */
+#include <linux/pci.h>
+#include <linux/pci-acpi.h>
+#include <linux/msi.h>
+#include <linux/bitfield.h>
+#include <linux/pci-tph.h>
+
+#include "pci.h"
+
+/* System-wide TPH disabled */
+static bool pci_tph_disabled;
+
+#ifdef CONFIG_ACPI
+/*
+ * The st_info struct defines the Steering Tag (ST) info returned by the
+ * firmware PCI ACPI _DSM method (rev=0x7, func=0xF, "_DSM to Query Cache
+ * Locality TPH Features"), as specified in the approved ECN for PCI Firmware
+ * Spec and available at https://members.pcisig.com/wg/PCI-SIG/document/15470.
+ *
+ * @vm_st_valid:  8-bit ST for volatile memory is valid
+ * @vm_xst_valid: 16-bit extended ST for volatile memory is valid
+ * @vm_ph_ignore: 1 => PH was and will be ignored, 0 => PH should be supplied
+ * @vm_st:        8-bit ST for volatile mem
+ * @vm_xst:       16-bit extended ST for volatile mem
+ * @pm_st_valid:  8-bit ST for persistent memory is valid
+ * @pm_xst_valid: 16-bit extended ST for persistent memory is valid
+ * @pm_ph_ignore: 1 => PH was and will be ignored, 0 => PH should be supplied
+ * @pm_st:        8-bit ST for persistent mem
+ * @pm_xst:       16-bit extended ST for persistent mem
+ */
+union st_info {
+	struct {
+		u64 vm_st_valid : 1;
+		u64 vm_xst_valid : 1;
+		u64 vm_ph_ignore : 1;
+		u64 rsvd1 : 5;
+		u64 vm_st : 8;
+		u64 vm_xst : 16;
+		u64 pm_st_valid : 1;
+		u64 pm_xst_valid : 1;
+		u64 pm_ph_ignore : 1;
+		u64 rsvd2 : 5;
+		u64 pm_st : 8;
+		u64 pm_xst : 16;
+	};
+	u64 value;
+};
+
+static u16 tph_extract_tag(enum tph_mem_type mem_type, u8 req_type,
+			   union st_info *info)
+{
+	switch (req_type) {
+	case PCI_TPH_REQ_TPH_ONLY: /* 8-bit tag */
+		switch (mem_type) {
+		case TPH_MEM_TYPE_VM:
+			if (info->vm_st_valid)
+				return info->vm_st;
+			break;
+		case TPH_MEM_TYPE_PM:
+			if (info->pm_st_valid)
+				return info->pm_st;
+			break;
+		}
+		break;
+	case PCI_TPH_REQ_EXT_TPH: /* 16-bit tag */
+		switch (mem_type) {
+		case TPH_MEM_TYPE_VM:
+			if (info->vm_xst_valid)
+				return info->vm_xst;
+			break;
+		case TPH_MEM_TYPE_PM:
+			if (info->pm_xst_valid)
+				return info->pm_xst;
+			break;
+		}
+		break;
+	default:
+		return 0;
+	}
+
+	return 0;
+}
+
+#define TPH_ST_DSM_FUNC_INDEX	0xF
+static acpi_status tph_invoke_dsm(acpi_handle handle, u32 cpu_uid,
+				  union st_info *st_out)
+{
+	union acpi_object arg3[3], in_obj, *out_obj;
+
+	if (!acpi_check_dsm(handle, &pci_acpi_dsm_guid, 7,
+			    BIT(TPH_ST_DSM_FUNC_INDEX)))
+		return AE_ERROR;
+
+	/* DWORD: feature ID (0 for processor cache ST query) */
+	arg3[0].integer.type = ACPI_TYPE_INTEGER;
+	arg3[0].integer.value = 0;
+
+	/* DWORD: target UID */
+	arg3[1].integer.type = ACPI_TYPE_INTEGER;
+	arg3[1].integer.value = cpu_uid;
+
+	/* QWORD: properties, all 0's */
+	arg3[2].integer.type = ACPI_TYPE_INTEGER;
+	arg3[2].integer.value = 0;
+
+	in_obj.type = ACPI_TYPE_PACKAGE;
+	in_obj.package.count = ARRAY_SIZE(arg3);
+	in_obj.package.elements = arg3;
+
+	out_obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 7,
+				    TPH_ST_DSM_FUNC_INDEX, &in_obj);
+	if (!out_obj)
+		return AE_ERROR;
+
+	if (out_obj->type != ACPI_TYPE_BUFFER) {
+		ACPI_FREE(out_obj);
+		return AE_ERROR;
+	}
+
+	st_out->value = *((u64 *)(out_obj->buffer.pointer));
+
+	ACPI_FREE(out_obj);
+
+	return AE_OK;
+}
+#endif
+
+/* Update the TPH Requester Enable field of TPH Control Register */
+static void set_ctrl_reg_req_en(struct pci_dev *pdev, u8 req_type)
+{
+	u32 reg;
+
+	pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, &reg);
+
+	reg &= ~PCI_TPH_CTRL_REQ_EN_MASK;
+	reg |= FIELD_PREP(PCI_TPH_CTRL_REQ_EN_MASK, req_type);
+
+	pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, reg);
+}
+
+static u8 get_st_modes(struct pci_dev *pdev)
+{
+	u32 reg;
+
+	pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CAP, &reg);
+	reg &= PCI_TPH_CAP_ST_NS | PCI_TPH_CAP_ST_IV | PCI_TPH_CAP_ST_DS;
+
+	return reg;
+}
+
+static u32 get_st_table_loc(struct pci_dev *pdev)
+{
+	u32 reg;
+
+	pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CAP, &reg);
+
+	return FIELD_GET(PCI_TPH_CAP_LOC_MASK, reg);
+}
+
+/*
+ * Return the size of ST table. If ST table is not in TPH Requester Extended
+ * Capability space, return 0. Otherwise return the ST Table Size + 1.
+ */
+static u16 get_st_table_size(struct pci_dev *pdev)
+{
+	u32 reg;
+	u32 loc;
+
+	/* Check ST table location first */
+	loc = get_st_table_loc(pdev);
+
+	/* Convert loc to match with PCI_TPH_LOC_* defined in pci_regs.h */
+	loc = FIELD_PREP(PCI_TPH_CAP_LOC_MASK, loc);
+	if (loc != PCI_TPH_LOC_CAP)
+		return 0;
+
+	pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CAP, &reg);
+
+	return FIELD_GET(PCI_TPH_CAP_ST_MASK, reg) + 1;
+}
+
+/* Return device's Root Port completer capability */
+static u8 get_rp_completer_type(struct pci_dev *pdev)
+{
+	struct pci_dev *rp;
+	u32 reg;
+	int ret;
+
+	rp = pcie_find_root_port(pdev);
+	if (!rp)
+		return 0;
+
+	ret = pcie_capability_read_dword(rp, PCI_EXP_DEVCAP2, &reg);
+	if (ret)
+		return 0;
+
+	return FIELD_GET(PCI_EXP_DEVCAP2_TPH_COMP_MASK, reg);
+}
+
+/* Write ST to MSI-X vector control reg - Return 0 if OK, otherwise -errno */
+static int write_tag_to_msix(struct pci_dev *pdev, int msix_idx, u16 tag)
+{
+#ifdef CONFIG_PCI_MSI
+	struct msi_desc *msi_desc = NULL;
+	void __iomem *vec_ctrl;
+	u32 val;
+	int err = 0;
+
+	msi_lock_descs(&pdev->dev);
+
+	/* Find the msi_desc entry with matching msix_idx */
+	msi_for_each_desc(msi_desc, &pdev->dev, MSI_DESC_ASSOCIATED) {
+		if (msi_desc->msi_index == msix_idx)
+			break;
+	}
+
+	if (!msi_desc) {
+		err = -ENXIO;
+		goto err_out;
+	}
+
+	/* Get the vector control register (offset 0xc) pointed by msix_idx */
+	vec_ctrl = pdev->msix_base + msix_idx * PCI_MSIX_ENTRY_SIZE;
+	vec_ctrl += PCI_MSIX_ENTRY_VECTOR_CTRL;
+
+	val = readl(vec_ctrl);
+	val &= ~PCI_MSIX_ENTRY_CTRL_ST;
+	val |= FIELD_PREP(PCI_MSIX_ENTRY_CTRL_ST, tag);
+	writel(val, vec_ctrl);
+
+	/* Read back to flush the update */
+	val = readl(vec_ctrl);
+
+err_out:
+	msi_unlock_descs(&pdev->dev);
+	return err;
+#else
+	return -ENODEV;
+#endif
+}
+
+/* Write tag to ST table - Return 0 if OK, otherwise -errno */
+static int write_tag_to_st_table(struct pci_dev *pdev, int index, u16 tag)
+{
+	int st_table_size;
+	int offset;
+
+	/* Check if index is out of bound */
+	st_table_size = get_st_table_size(pdev);
+	if (index >= st_table_size)
+		return -ENXIO;
+
+	offset = pdev->tph_cap + PCI_TPH_BASE_SIZEOF + index * sizeof(u16);
+
+	return pci_write_config_word(pdev, offset, tag);
+}
+
+/**
+ * pcie_tph_get_cpu_st() - Retrieve Steering Tag for a target memory associated
+ * with a specific CPU
+ * @pdev: PCI device
+ * @mem_type: target memory type (volatile or persistent RAM)
+ * @cpu_uid: associated CPU id
+ * @tag: Steering Tag to be returned
+ *
+ * Return the Steering Tag for a target memory that is associated with a
+ * specific CPU as indicated by cpu_uid.
+ *
+ * Return: 0 if success, otherwise negative value (-errno)
+ */
+int pcie_tph_get_cpu_st(struct pci_dev *pdev, enum tph_mem_type mem_type,
+			unsigned int cpu_uid, u16 *tag)
+{
+#ifdef CONFIG_ACPI
+	struct pci_dev *rp;
+	acpi_handle rp_acpi_handle;
+	union st_info info;
+
+	rp = pcie_find_root_port(pdev);
+	if (!rp || !rp->bus || !rp->bus->bridge)
+		return -ENODEV;
+
+	rp_acpi_handle = ACPI_HANDLE(rp->bus->bridge);
+
+	if (tph_invoke_dsm(rp_acpi_handle, cpu_uid, &info) != AE_OK) {
+		*tag = 0;
+		return -EINVAL;
+	}
+
+	*tag = tph_extract_tag(mem_type, pdev->tph_req_type, &info);
+
+	pci_dbg(pdev, "get steering tag: mem_type=%s, cpu_uid=%d, tag=%#04x\n",
+		(mem_type == TPH_MEM_TYPE_VM) ? "volatile" : "persistent",
+		cpu_uid, *tag);
+
+	return 0;
+#else
+	return -ENODEV;
+#endif
+}
+EXPORT_SYMBOL(pcie_tph_get_cpu_st);
+
+/**
+ * pcie_tph_set_st_entry() - Set Steering Tag in the ST table entry
+ * @pdev: PCI device
+ * @index: ST table entry index
+ * @tag: Steering Tag to be written
+ *
+ * Figure out the proper location of ST table, either in the MSI-X table or
+ * in the TPH Extended Capability space, and write the Steering Tag into
+ * the ST entry pointed by index.
+ *
+ * Return: 0 if success, otherwise negative value (-errno)
+ */
+int pcie_tph_set_st_entry(struct pci_dev *pdev, unsigned int index, u16 tag)
+{
+	u32 loc;
+	int err = 0;
+
+	if (!pdev->tph_cap)
+		return -EINVAL;
+
+	if (!pdev->tph_enabled)
+		return -EINVAL;
+
+	/* No need to write tag if device is in "No ST Mode" */
+	if (pdev->tph_mode == PCI_TPH_ST_NS_MODE)
+		return 0;
+
+	/*
+	 * Disable TPH before updating ST to avoid potential instability as
+	 * cautioned in PCIe r6.2, sec 6.17.3, "ST Modes of Operation"
+	 */
+	set_ctrl_reg_req_en(pdev, PCI_TPH_REQ_DISABLE);
+
+	loc = get_st_table_loc(pdev);
+	/* Convert loc to match with PCI_TPH_LOC_* */
+	loc = FIELD_PREP(PCI_TPH_CAP_LOC_MASK, loc);
+
+	switch (loc) {
+	case PCI_TPH_LOC_MSIX:
+		err = write_tag_to_msix(pdev, index, tag);
+		break;
+	case PCI_TPH_LOC_CAP:
+		err = write_tag_to_st_table(pdev, index, tag);
+		break;
+	default:
+		err = -EINVAL;
+	}
+
+	if (err) {
+		pcie_disable_tph(pdev);
+		return err;
+	}
+
+	set_ctrl_reg_req_en(pdev, pdev->tph_mode);
+
+	pci_dbg(pdev, "set steering tag: %s table, index=%d, tag=%#04x\n",
+		(loc == PCI_TPH_LOC_MSIX) ? "MSI-X" : "ST", index, tag);
+
+	return 0;
+}
+EXPORT_SYMBOL(pcie_tph_set_st_entry);
+
+/**
+ * pcie_disable_tph - Turn off TPH support for device
+ * @pdev: PCI device
+ *
+ * Return: none
+ */
+void pcie_disable_tph(struct pci_dev *pdev)
+{
+	if (!pdev->tph_cap)
+		return;
+
+	if (!pdev->tph_enabled)
+		return;
+
+	pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, 0);
+
+	pdev->tph_mode = 0;
+	pdev->tph_req_type = 0;
+	pdev->tph_enabled = 0;
+}
+EXPORT_SYMBOL(pcie_disable_tph);
+
+/**
+ * pcie_enable_tph - Enable TPH support for device using a specific ST mode
+ * @pdev: PCI device
+ * @mode: ST mode to enable. Current supported modes include:
+ *
+ *   - PCI_TPH_ST_NS_MODE: NO ST Mode
+ *   - PCI_TPH_ST_IV_MODE: Interrupt Vector Mode
+ *   - PCI_TPH_ST_DS_MODE: Device Specific Mode
+ *
+ * Check whether the mode is actually supported by the device before enabling
+ * and return an error if not. Additionally determine what types of requests,
+ * TPH or extended TPH, can be issued by the device based on its TPH requester
+ * capability and the Root Port's completer capability.
+ *
+ * Return: 0 on success, otherwise negative value (-errno)
+ */
+int pcie_enable_tph(struct pci_dev *pdev, int mode)
+{
+	u32 reg;
+	u8 dev_modes;
+	u8 rp_req_type;
+
+	/* Honor "notph" kernel parameter */
+	if (pci_tph_disabled)
+		return -EINVAL;
+
+	if (!pdev->tph_cap)
+		return -EINVAL;
+
+	if (pdev->tph_enabled)
+		return -EBUSY;
+
+	/* Sanitize and check ST mode compatibility */
+	mode &= PCI_TPH_CTRL_MODE_SEL_MASK;
+	dev_modes = get_st_modes(pdev);
+	if (!((1 << mode) & dev_modes))
+		return -EINVAL;
+
+	pdev->tph_mode = mode;
+
+	/* Get req_type supported by device and its Root Port */
+	pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CAP, &reg);
+	if (FIELD_GET(PCI_TPH_CAP_EXT_TPH, reg))
+		pdev->tph_req_type = PCI_TPH_REQ_EXT_TPH;
+	else
+		pdev->tph_req_type = PCI_TPH_REQ_TPH_ONLY;
+
+	rp_req_type = get_rp_completer_type(pdev);
+
+	/* Final req_type is the smallest value of two */
+	pdev->tph_req_type = min(pdev->tph_req_type, rp_req_type);
+
+	if (pdev->tph_req_type == PCI_TPH_REQ_DISABLE)
+		return -EINVAL;
+
+	/* Write them into TPH control register */
+	pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, &reg);
+
+	reg &= ~PCI_TPH_CTRL_MODE_SEL_MASK;
+	reg |= FIELD_PREP(PCI_TPH_CTRL_MODE_SEL_MASK, pdev->tph_mode);
+
+	reg &= ~PCI_TPH_CTRL_REQ_EN_MASK;
+	reg |= FIELD_PREP(PCI_TPH_CTRL_REQ_EN_MASK, pdev->tph_req_type);
+
+	pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, reg);
+
+	pdev->tph_enabled = 1;
+
+	return 0;
+}
+EXPORT_SYMBOL(pcie_enable_tph);
+
+void pci_restore_tph_state(struct pci_dev *pdev)
+{
+	struct pci_cap_saved_state *save_state;
+	int num_entries, i, offset;
+	u16 *st_entry;
+	u32 *cap;
+
+	if (!pdev->tph_cap)
+		return;
+
+	if (!pdev->tph_enabled)
+		return;
+
+	save_state = pci_find_saved_ext_cap(pdev, PCI_EXT_CAP_ID_TPH);
+	if (!save_state)
+		return;
+
+	/* Restore control register and all ST entries */
+	cap = &save_state->cap.data[0];
+	pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, *cap++);
+	st_entry = (u16 *)cap;
+	offset = PCI_TPH_BASE_SIZEOF;
+	num_entries = get_st_table_size(pdev);
+	for (i = 0; i < num_entries; i++) {
+		pci_write_config_word(pdev, pdev->tph_cap + offset,
+				      *st_entry++);
+		offset += sizeof(u16);
+	}
+}
+
+void pci_save_tph_state(struct pci_dev *pdev)
+{
+	struct pci_cap_saved_state *save_state;
+	int num_entries, i, offset;
+	u16 *st_entry;
+	u32 *cap;
+
+	if (!pdev->tph_cap)
+		return;
+
+	if (!pdev->tph_enabled)
+		return;
+
+	save_state = pci_find_saved_ext_cap(pdev, PCI_EXT_CAP_ID_TPH);
+	if (!save_state)
+		return;
+
+	/* Save control register */
+	cap = &save_state->cap.data[0];
+	pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, cap++);
+
+	/* Save all ST entries in extended capability structure */
+	st_entry = (u16 *)cap;
+	offset = PCI_TPH_BASE_SIZEOF;
+	num_entries = get_st_table_size(pdev);
+	for (i = 0; i < num_entries; i++) {
+		pci_read_config_word(pdev, pdev->tph_cap + offset,
+				     st_entry++);
+		offset += sizeof(u16);
+	}
+}
+
+void pci_no_tph(void)
+{
+	pci_tph_disabled = true;
+
+	pr_info("PCIe TPH is disabled\n");
+}
+
+void pci_tph_init(struct pci_dev *pdev)
+{
+	int num_entries;
+	u32 save_size;
+
+	pdev->tph_cap = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_TPH);
+	if (!pdev->tph_cap)
+		return;
+
+	num_entries = get_st_table_size(pdev);
+	save_size = sizeof(u32) + num_entries * sizeof(u16);
+	pci_add_ext_cap_save_buffer(pdev, PCI_EXT_CAP_ID_TPH, save_size);
+}