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Wysocki" Cc: Koba Ko , Mika Westerberg , "David E . Box" , Sathyanarayanan Kuppuswamy , linux-pci@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Bjorn Helgaas Subject: [PATCH v4 4/9] PCI/PTM: Add pci_suspend_ptm() and pci_resume_ptm() Date: Fri, 9 Sep 2022 15:25:00 -0500 Message-Id: <20220909202505.314195-5-helgaas@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220909202505.314195-1-helgaas@kernel.org> References: <20220909202505.314195-1-helgaas@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org From: Bjorn Helgaas We disable PTM during suspend because that allows some Root Ports to enter lower-power PM states, which means we also need to disable PTM for all downstream devices. Add pci_suspend_ptm() and pci_resume_ptm() for this purpose. pci_enable_ptm() and pci_disable_ptm() are for drivers to use to enable or disable PTM. They use dev->ptm_enabled to keep track of whether PTM should be enabled. pci_suspend_ptm() and pci_resume_ptm() are PCI core-internal functions to temporarily disable PTM during suspend and (depending on dev->ptm_enabled) re-enable PTM during resume. Enable/disable/suspend/resume all use internal __pci_enable_ptm() and __pci_disable_ptm() functions that only update the PTM Control register. Outline: pci_enable_ptm(struct pci_dev *dev) { __pci_enable_ptm(dev); dev->ptm_enabled = 1; pci_ptm_info(dev); } pci_disable_ptm(struct pci_dev *dev) { if (dev->ptm_enabled) { __pci_disable_ptm(dev); dev->ptm_enabled = 0; } } pci_suspend_ptm(struct pci_dev *dev) { if (dev->ptm_enabled) __pci_disable_ptm(dev); } pci_resume_ptm(struct pci_dev *dev) { if (dev->ptm_enabled) __pci_enable_ptm(dev); } Nothing currently calls pci_resume_ptm(); the suspend path saves the PTM state before disabling PTM, so the PTM state restore in the resume path implicitly re-enables it. A future change will use pci_resume_ptm() to fix some problems with this approach. Signed-off-by: Bjorn Helgaas --- drivers/pci/pci.c | 4 +-- drivers/pci/pci.h | 6 ++-- drivers/pci/pcie/ptm.c | 71 +++++++++++++++++++++++++++++++++--------- include/linux/pci.h | 2 ++ 4 files changed, 65 insertions(+), 18 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 95bc329e74c0..83818f81577d 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -2714,7 +2714,7 @@ int pci_prepare_to_sleep(struct pci_dev *dev) * lower-power idle state as a whole. */ if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) - pci_disable_ptm(dev); + pci_suspend_ptm(dev); pci_enable_wake(dev, target_state, wakeup); @@ -2772,7 +2772,7 @@ int pci_finish_runtime_suspend(struct pci_dev *dev) * lower-power idle state as a whole. */ if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) - pci_disable_ptm(dev); + pci_suspend_ptm(dev); __pci_enable_wake(dev, target_state, pci_dev_run_wake(dev)); diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 785f31086313..ce4a277e3f41 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -507,11 +507,13 @@ static inline int pci_iov_bus_range(struct pci_bus *bus) #ifdef CONFIG_PCIE_PTM void pci_save_ptm_state(struct pci_dev *dev); void pci_restore_ptm_state(struct pci_dev *dev); -void pci_disable_ptm(struct pci_dev *dev); +void pci_suspend_ptm(struct pci_dev *dev); +void pci_resume_ptm(struct pci_dev *dev); #else static inline void pci_save_ptm_state(struct pci_dev *dev) { } static inline void pci_restore_ptm_state(struct pci_dev *dev) { } -static inline void pci_disable_ptm(struct pci_dev *dev) { } +static inline void pci_suspend_ptm(struct pci_dev *dev) { } +static inline void pci_resume_ptm(struct pci_dev *dev) { } #endif unsigned long pci_cardbus_resource_alignment(struct resource *); diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c index ba1d50c965fa..70a28b74e721 100644 --- a/drivers/pci/pcie/ptm.c +++ b/drivers/pci/pcie/ptm.c @@ -29,7 +29,7 @@ static void pci_ptm_info(struct pci_dev *dev) dev->ptm_root ? " (root)" : "", clock_desc); } -void pci_disable_ptm(struct pci_dev *dev) +static void __pci_disable_ptm(struct pci_dev *dev) { u16 ptm = dev->ptm_cap; u16 ctrl; @@ -42,6 +42,21 @@ void pci_disable_ptm(struct pci_dev *dev) pci_write_config_word(dev, ptm + PCI_PTM_CTRL, ctrl); } +/** + * pci_disable_ptm() - Disable Precision Time Measurement + * @dev: PCI device + * + * Disable Precision Time Measurement for @dev. + */ +void pci_disable_ptm(struct pci_dev *dev) +{ + if (dev->ptm_enabled) { + __pci_disable_ptm(dev); + dev->ptm_enabled = 0; + } +} +EXPORT_SYMBOL(pci_disable_ptm); + void pci_save_ptm_state(struct pci_dev *dev) { u16 ptm = dev->ptm_cap; @@ -151,18 +166,8 @@ void pci_ptm_init(struct pci_dev *dev) pci_enable_ptm(dev, NULL); } -/** - * pci_enable_ptm() - Enable Precision Time Measurement - * @dev: PCI device - * @granularity: pointer to return granularity - * - * Enable Precision Time Measurement for @dev. If successful and - * @granularity is non-NULL, return the Effective Granularity. - * - * Return: zero if successful, or -EINVAL if @dev lacks a PTM Capability or - * is not a PTM Root and lacks an upstream path of PTM-enabled devices. - */ -int pci_enable_ptm(struct pci_dev *dev, u8 *granularity) +/* Enable PTM in the Control register if possible */ +static int __pci_enable_ptm(struct pci_dev *dev) { u16 ptm = dev->ptm_cap; struct pci_dev *ups; @@ -191,8 +196,29 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity) ctrl |= PCI_PTM_CTRL_ROOT; pci_write_config_dword(dev, ptm + PCI_PTM_CTRL, ctrl); + return 0; +} + +/** + * pci_enable_ptm() - Enable Precision Time Measurement + * @dev: PCI device + * @granularity: pointer to return granularity + * + * Enable Precision Time Measurement for @dev. If successful and + * @granularity is non-NULL, return the Effective Granularity. + * + * Return: zero if successful, or -EINVAL if @dev lacks a PTM Capability or + * is not a PTM Root and lacks an upstream path of PTM-enabled devices. + */ +int pci_enable_ptm(struct pci_dev *dev, u8 *granularity) +{ + int rc; + + rc = __pci_enable_ptm(dev); + if (rc) + return rc; + dev->ptm_enabled = 1; - pci_ptm_info(dev); if (granularity) @@ -201,6 +227,23 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity) } EXPORT_SYMBOL(pci_enable_ptm); +/* + * Disable PTM, but preserve dev->ptm_enabled so we silently re-enable it on + * resume if necessary. + */ +void pci_suspend_ptm(struct pci_dev *dev) +{ + if (dev->ptm_enabled) + __pci_disable_ptm(dev); +} + +/* If PTM was enabled before suspend, re-enable it when resuming */ +void pci_resume_ptm(struct pci_dev *dev) +{ + if (dev->ptm_enabled) + __pci_enable_ptm(dev); +} + bool pcie_ptm_enabled(struct pci_dev *dev) { if (!dev) diff --git a/include/linux/pci.h b/include/linux/pci.h index 54be939023a3..cb5f796e3319 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1678,10 +1678,12 @@ bool pci_ats_disabled(void); #ifdef CONFIG_PCIE_PTM int pci_enable_ptm(struct pci_dev *dev, u8 *granularity); +void pci_disable_ptm(struct pci_dev *dev); bool pcie_ptm_enabled(struct pci_dev *dev); #else static inline int pci_enable_ptm(struct pci_dev *dev, u8 *granularity) { return -EINVAL; } +static inline void pci_disable_ptm(struct pci_dev *dev) { } static inline bool pcie_ptm_enabled(struct pci_dev *dev) { return false; } #endif