PCI: Add ACS quirk for Zhaoxin Root/Downstream Ports

Many Zhaoxin Root Ports and Switch Downstream Ports do provide ACS-like
capability but have no ACS Capability Structure.  Peer-to-Peer transactions
could be blocked between these ports, so add quirk so devices behind them
could be assigned to different IOMMU group.

Link: https://lore.kernel.org/r/20200327091148.5190-4-RaymondPang-oc@zhaoxin.comSigned-off-by: Raymond Pang <RaymondPang-oc@zhaoxin.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/quirks.c

@@ -4399,6 +4399,29 @@ static int pci_quirk_xgene_acs(struct pci_dev *dev, u16 acs_flags)
 		PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF);
 }
 
+/*
+ * Many Zhaoxin Root Ports and Switch Downstream Ports have no ACS capability.
+ * But the implementation could block peer-to-peer transactions between them
+ * and provide ACS-like functionality.
+ */
+static int  pci_quirk_zhaoxin_pcie_ports_acs(struct pci_dev *dev, u16 acs_flags)
+{
+	if (!pci_is_pcie(dev) ||
+	    ((pci_pcie_type(dev) != PCI_EXP_TYPE_ROOT_PORT) &&
+	     (pci_pcie_type(dev) != PCI_EXP_TYPE_DOWNSTREAM)))
+		return -ENOTTY;
+
+	switch (dev->device) {
+	case 0x0710 ... 0x071e:
+	case 0x0721:
+	case 0x0723 ... 0x0732:
+		return pci_acs_ctrl_enabled(acs_flags,
+			PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF);
+	}
+
+	return false;
+}
+
 /*
  * Many Intel PCH Root Ports do provide ACS-like features to disable peer
  * transactions and validate bus numbers in requests, but do not provide an
@@ -4705,6 +4728,8 @@ static const struct pci_dev_acs_enabled {
 	{ PCI_VENDOR_ID_ZHAOXIN, 0x3038, pci_quirk_mf_endpoint_acs },
 	{ PCI_VENDOR_ID_ZHAOXIN, 0x3104, pci_quirk_mf_endpoint_acs },
 	{ PCI_VENDOR_ID_ZHAOXIN, 0x9083, pci_quirk_mf_endpoint_acs },
+	/* Zhaoxin Root/Downstream Ports */
+	{ PCI_VENDOR_ID_ZHAOXIN, PCI_ANY_ID, pci_quirk_zhaoxin_pcie_ports_acs },
 	{ 0 }
 };