Commit e8bdc5ea authored by Bjorn Helgaas's avatar Bjorn Helgaas
Browse files

PCI/PTM: Add pci_suspend_ptm() and pci_resume_ptm() 

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.

Link: https://lore.kernel.org/r/20220909202505.314195-5-helgaas@kernel.org


Tested-by: default avatarRajvi Jingar <rajvi.jingar@linux.intel.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
parent 118b9dfd

drivers/pci/pci.c

+2 −2
Original line number Diff line number Diff line
@@ -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));

drivers/pci/pci.h

+4 −2
Original line number Diff line number Diff line
@@ -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 *);

drivers/pci/pcie/ptm.c

+57 −14
Original line number Diff line number Diff line
@@ -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);

	dev->ptm_enabled = 1;

	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)

include/linux/pci.h

+2 −0
Original line number Diff line number Diff line
@@ -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