PCI: Add device-specific PCI ACS enable

Some devices support PCI ACS-like features, but don't report it using the
standard PCIe capabilities.  We already provide hooks for device-specific
testing of ACS, but not for device-specific enabling of ACS.  This provides
that setup hook.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 20 insertions, 6 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 1febe90831b4..b89502ff3139 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2180,21 +2180,18 @@ void pci_request_acs(void)
 }
 
 /**
- * pci_enable_acs - enable ACS if hardware support it
+ * pci_std_enable_acs - enable ACS on devices using standard ACS capabilites
  * @dev: the PCI device
  */
-void pci_enable_acs(struct pci_dev *dev)
+static int pci_std_enable_acs(struct pci_dev *dev)
 {
         int pos;
         u16 cap;
         u16 ctrl;
 
-        if (!pci_acs_enable)
-                return;
-
         pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ACS);
         if (!pos)
-                return;
+                return -ENODEV;
 
         pci_read_config_word(dev, pos + PCI_ACS_CAP, &cap);
         pci_read_config_word(dev, pos + PCI_ACS_CTRL, &ctrl);
@@ -2212,6 +2209,23 @@ void pci_enable_acs(struct pci_dev *dev)
         ctrl |= (cap & PCI_ACS_UF);
 
         pci_write_config_word(dev, pos + PCI_ACS_CTRL, ctrl);
+
+        return 0;
+}
+
+/**
+ * pci_enable_acs - enable ACS if hardware support it
+ * @dev: the PCI device
+ */
+void pci_enable_acs(struct pci_dev *dev)
+{
+        if (!pci_acs_enable)
+                return;
+
+        if (!pci_std_enable_acs(dev))
+                return;
+
+        pci_dev_specific_enable_acs(dev);
 }
 
 static bool pci_acs_flags_enabled(struct pci_dev *pdev, u16 acs_flags)