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Commit eec097d4 authored by Bjorn Helgaas's avatar Bjorn Helgaas
Browse files

PCI: Add pci_enable_ptm() for drivers to enable PTM on endpoints 



Add an pci_enable_ptm() interface so drivers can enable PTM.

The PCI core enables PTM on PTM Roots and switches automatically, but we
don't enable PTM on endpoints unless a driver requests it.

Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 9bb04a0c

drivers/pci/pcie/ptm.c

+45 −0
Original line number Diff line number Diff line
@@ -68,3 +68,48 @@ void pci_ptm_init(struct pci_dev *dev) 


	pci_ptm_info(dev);

}



int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)

{

	int pos;

	u32 cap, ctrl;

	struct pci_dev *ups;



	if (!pci_is_pcie(dev))

		return -EINVAL;



	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);

	if (!pos)

		return -EINVAL;



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

	if (!(cap & PCI_PTM_CAP_REQ))

		return -EINVAL;



	/*

	 * For a PCIe Endpoint, PTM is only useful if the endpoint can

	 * issue PTM requests to upstream devices that have PTM enabled.

	 *

	 * For Root Complex Integrated Endpoints, there is no upstream

	 * device, so there must be some implementation-specific way to

	 * associate the endpoint with a time source.

	 */

	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ENDPOINT) {

		ups = pci_upstream_bridge(dev);

		if (!ups || !ups->ptm_enabled)

			return -EINVAL;

	} else if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) {

	} else

		return -EINVAL;



	ctrl = PCI_PTM_CTRL_ENABLE;

	pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl);

	dev->ptm_enabled = 1;



	pci_ptm_info(dev);



	if (granularity)

		*granularity = 0;

	return 0;

}

EXPORT_SYMBOL(pci_enable_ptm);

include/linux/pci.h

+7 −0
Original line number Diff line number Diff line
@@ -1407,6 +1407,13 @@ static inline void pci_disable_ats(struct pci_dev *d) { } 
static inline int pci_ats_queue_depth(struct pci_dev *d) { return -ENODEV; }

#endif



#ifdef CONFIG_PCIE_PTM

int pci_enable_ptm(struct pci_dev *dev, u8 *granularity);

#else

static inline int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)

{ return -EINVAL; }

#endif



void pci_cfg_access_lock(struct pci_dev *dev);

bool pci_cfg_access_trylock(struct pci_dev *dev);

void pci_cfg_access_unlock(struct pci_dev *dev);

include/uapi/linux/pci_regs.h

+1 −0
Original line number Diff line number Diff line
@@ -967,6 +967,7 @@ 


/* Precision Time Measurement */

#define PCI_PTM_CAP			0x04	    /* PTM Capability */

#define  PCI_PTM_CAP_REQ		0x00000001  /* Requester capable */

#define  PCI_PTM_CAP_ROOT		0x00000004  /* Root capable */

#define PCI_PTM_CTRL			0x08	    /* PTM Control */

#define  PCI_PTM_CTRL_ENABLE		0x00000001  /* PTM enable */