PCI: Add Precision Time Measurement (PTM) support (9bb04a0c) · Commits · 戴 / test

drivers/pci/pci.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -332,6 +332,12 @@ static inline resource_size_t pci_resource_alignment(struct pci_dev *dev,

		void pci_enable_acs(struct pci_dev *dev);

		#ifdef CONFIG_PCIE_PTM
		void pci_ptm_init(struct pci_dev *dev);
		#else
		static inline void pci_ptm_init(struct pci_dev *dev) { }
		#endif

		struct pci_dev_reset_methods {
		u16 vendor;
		u16 device;

drivers/pci/pcie/Kconfig

+11 −0

Original line number	Diff line number	Diff line
		@@ -92,3 +92,14 @@ config PCIE_DPC
		will be handled by the DPC driver. If your system doesn't
		have this capability or you do not want to use this feature,
		it is safe to answer N.

		config PCIE_PTM
		bool "PCIe Precision Time Measurement support"
		default n
		depends on PCIEPORTBUS
		help
		This enables PCI Express Precision Time Measurement (PTM)
		support.

		This is only useful if you have devices that support PTM, but it
		is safe to enable even if you don't.

drivers/pci/pcie/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -16,3 +16,4 @@ obj-$(CONFIG_PCIEAER) += aer/
		obj-$(CONFIG_PCIE_PME) += pme.o

		obj-$(CONFIG_PCIE_DPC) += pcie-dpc.o
		obj-$(CONFIG_PCIE_PTM) += ptm.o

drivers/pci/pcie/ptm.c

0 → 100644

+70 −0

Original line number	Diff line number	Diff line
		/*
		* PCI Express Precision Time Measurement
		* Copyright (c) 2016, Intel Corporation.
		*
		* This program is free software; you can redistribute it and/or modify it
		* under the terms and conditions of the GNU General Public License,
		* version 2, as published by the Free Software Foundation.
		*
		* This program is distributed in the hope it will be useful, but WITHOUT
		* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
		* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
		* more details.
		*/

		#include <linux/module.h>
		#include <linux/init.h>
		#include <linux/pci.h>
		#include "../pci.h"

		static void pci_ptm_info(struct pci_dev *dev)
		{
		dev_info(&dev->dev, "PTM enabled%s\n", dev->ptm_root ? " (root)" : "");
		}

		void pci_ptm_init(struct pci_dev *dev)
		{
		int pos;
		u32 cap, ctrl;
		struct pci_dev *ups;

		if (!pci_is_pcie(dev))
		return;

		pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
		if (!pos)
		return;

		/*
		* Enable PTM only on interior devices (root ports, switch ports,
		* etc.) on the assumption that it causes no link traffic until an
		* endpoint enables it.
		*/
		if ((pci_pcie_type(dev) == PCI_EXP_TYPE_ENDPOINT \|\|
		pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END))
		return;

		pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap);

		/*
		* There's no point in enabling PTM unless it's enabled in the
		* upstream device or this device can be a PTM Root itself. Per
		* the spec recommendation (PCIe r3.1, sec 7.32.3), select the
		* furthest upstream Time Source as the PTM Root.
		*/
		ups = pci_upstream_bridge(dev);
		if (ups && ups->ptm_enabled) {
		ctrl = PCI_PTM_CTRL_ENABLE;
		} else {
		if (cap & PCI_PTM_CAP_ROOT) {
		ctrl = PCI_PTM_CTRL_ENABLE \| PCI_PTM_CTRL_ROOT;
		dev->ptm_root = 1;
		} else
		return;
		}

		pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl);
		dev->ptm_enabled = 1;

		pci_ptm_info(dev);
		}

drivers/pci/probe.c

+3 −0

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		@@ -1667,6 +1667,9 @@ static void pci_init_capabilities(struct pci_dev *dev)
		pci_enable_acs(dev);

		pci_cleanup_aer_error_status_regs(dev);

		/* Precision Time Measurement */
		pci_ptm_init(dev);
		}

		/*

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