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authorKuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>2019-02-19 11:06:09 -0800
committerJoerg Roedel <jroedel@suse.de>2019-02-26 11:08:07 +0100
commit8c938ddc6df3bbe72809db1be6c9f3af83f5d7a9 (patch)
treea537049ef8689b691c19a966137140965bb10f83 /drivers/pci/ats.c
parent1b84778a62ad6d0d97ace457072d93933f306ef5 (diff)
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: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/pci/ats.c')
-rw-r--r--drivers/pci/ats.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index 420cd0a578d0..97c08146534a 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -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