Commit 8c938ddc authored by Kuppuswamy Sathyanarayanan's avatar Kuppuswamy Sathyanarayanan Committed by Joerg Roedel
Browse files

PCI/ATS: Add pci_ats_page_aligned() interface 



Return the Page Aligned Request bit in the ATS Capability Register.

As per PCIe spec r4.0, sec 10.5.1.2, if the Page Aligned Request bit is
set, it indicates the Untranslated Addresses generated by the device are
always aligned to a 4096 byte boundary.

An IOMMU that can only translate page-aligned addresses can only be used
with devices that always produce aligned Untranslated Addresses. This
interface will be used by drivers for such IOMMUs to determine whether
devices can use the ATS service.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Suggested-by: default avatarAshok Raj <ashok.raj@intel.com>
Signed-off-by: default avatarKuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Acked-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 1b84778a

drivers/pci/ats.c

+27 −0
Original line number Diff line number Diff line
@@ -142,6 +142,33 @@ int pci_ats_queue_depth(struct pci_dev *dev) 
}

EXPORT_SYMBOL_GPL(pci_ats_queue_depth);



/**

 * pci_ats_page_aligned - Return Page Aligned Request bit status.

 * @pdev: the PCI device

 *

 * Returns 1, if the Untranslated Addresses generated by the device

 * are always aligned or 0 otherwise.

 *

 * Per PCIe spec r4.0, sec 10.5.1.2, if the Page Aligned Request bit

 * is set, it indicates the Untranslated Addresses generated by the

 * device are always aligned to a 4096 byte boundary.

 */

int pci_ats_page_aligned(struct pci_dev *pdev)

{

	u16 cap;



	if (!pdev->ats_cap)

		return 0;



	pci_read_config_word(pdev, pdev->ats_cap + PCI_ATS_CAP, &cap);



	if (cap & PCI_ATS_CAP_PAGE_ALIGNED)

		return 1;



	return 0;

}

EXPORT_SYMBOL_GPL(pci_ats_page_aligned);



#ifdef CONFIG_PCI_PRI

/**

 * pci_enable_pri - Enable PRI capability

include/linux/pci.h

+2 −0
Original line number Diff line number Diff line
@@ -1524,11 +1524,13 @@ void pci_ats_init(struct pci_dev *dev); 
int pci_enable_ats(struct pci_dev *dev, int ps);

void pci_disable_ats(struct pci_dev *dev);

int pci_ats_queue_depth(struct pci_dev *dev);

int pci_ats_page_aligned(struct pci_dev *dev);

#else

static inline void pci_ats_init(struct pci_dev *d) { }

static inline int pci_enable_ats(struct pci_dev *d, int ps) { return -ENODEV; }

static inline void pci_disable_ats(struct pci_dev *d) { }

static inline int pci_ats_queue_depth(struct pci_dev *d) { return -ENODEV; }

static inline int pci_ats_page_aligned(struct pci_dev *dev) { return 0; }

#endif



#ifdef CONFIG_PCIE_PTM

include/uapi/linux/pci_regs.h

+1 −0
Original line number Diff line number Diff line
@@ -866,6 +866,7 @@ 
#define PCI_ATS_CAP		0x04	/* ATS Capability Register */

#define  PCI_ATS_CAP_QDEP(x)	((x) & 0x1f)	/* Invalidate Queue Depth */

#define  PCI_ATS_MAX_QDEP	32	/* Max Invalidate Queue Depth */

#define  PCI_ATS_CAP_PAGE_ALIGNED	0x0020 /* Page Aligned Request */

#define PCI_ATS_CTRL		0x06	/* ATS Control Register */

#define  PCI_ATS_CTRL_ENABLE	0x8000	/* ATS Enable */

#define  PCI_ATS_CTRL_STU(x)	((x) & 0x1f)	/* Smallest Translation Unit */

CRA Git | Maintained and supported by SUSTech CRA and CCSE