From e5567f5f67621877726f99be040af9fbedda37dc Mon Sep 17 00:00:00 2001 From: Kuppuswamy Sathyanarayanan Date: Tue, 19 Feb 2019 11:04:51 -0800 Subject: PCI/ATS: Add pci_prg_resp_pasid_required() interface. Return the PRG Response PASID Required bit in the Page Request Status Register. As per PCIe spec r4.0, sec 10.5.2.3, if this bit is Set, the device expects a PASID TLP Prefix on PRG Response Messages when the corresponding Page Requests had a PASID TLP Prefix. If Clear, the device does not expect PASID TLP Prefixes on any PRG Response Message, and the device behavior is undefined if the device receives a PRG Response Message with a PASID TLP Prefix. Also the device behavior is undefined if this bit is Set and the device receives a PRG Response Message with no PASID TLP Prefix when the corresponding Page Requests had a PASID TLP Prefix. This function will be used by drivers like IOMMU, if it is required to check the status of the PRG Response PASID Required bit before enabling the PASID support of the device. Cc: Ashok Raj Cc: Jacob Pan Cc: Keith Busch Suggested-by: Ashok Raj Signed-off-by: Kuppuswamy Sathyanarayanan Acked-by: Bjorn Helgaas Signed-off-by: Joerg Roedel --- drivers/pci/ats.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'drivers') diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c index 5b78f3b1b918..420cd0a578d0 100644 --- a/drivers/pci/ats.c +++ b/drivers/pci/ats.c @@ -368,6 +368,36 @@ int pci_pasid_features(struct pci_dev *pdev) } EXPORT_SYMBOL_GPL(pci_pasid_features); +/** + * pci_prg_resp_pasid_required - Return PRG Response PASID Required bit + * status. + * @pdev: PCI device structure + * + * Returns 1 if PASID is required in PRG Response Message, 0 otherwise. + * + * Even though the PRG response PASID status is read from PRI Status + * Register, since this API will mainly be used by PASID users, this + * function is defined within #ifdef CONFIG_PCI_PASID instead of + * CONFIG_PCI_PRI. + */ +int pci_prg_resp_pasid_required(struct pci_dev *pdev) +{ + u16 status; + int pos; + + pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI); + if (!pos) + return 0; + + pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status); + + if (status & PCI_PRI_STATUS_PASID) + return 1; + + return 0; +} +EXPORT_SYMBOL_GPL(pci_prg_resp_pasid_required); + #define PASID_NUMBER_SHIFT 8 #define PASID_NUMBER_MASK (0x1f << PASID_NUMBER_SHIFT) /** -- cgit v1.2.3