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>

3 files changed, 47 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)
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 5cb726c193de..f681fb08f5e4 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -3461,3 +3461,28 @@ int pci_dev_specific_acs_enabled(struct pci_dev *dev, u16 acs_flags)
 
         return -ENOTTY;
 }
+
+static const struct pci_dev_enable_acs {
+        u16 vendor;
+        u16 device;
+        int (*enable_acs)(struct pci_dev *dev);
+} pci_dev_enable_acs[] = {
+        { 0 }
+};
+
+void pci_dev_specific_enable_acs(struct pci_dev *dev)
+{
+        const struct pci_dev_enable_acs *i;
+        int ret;
+
+        for (i = pci_dev_enable_acs; i->enable_acs; i++) {
+                if ((i->vendor == dev->vendor ||
+                     i->vendor == (u16)PCI_ANY_ID) &&
+                    (i->device == dev->device ||
+                     i->device == (u16)PCI_ANY_ID)) {
+                        ret = i->enable_acs(dev);
+                        if (ret >= 0)
+                                return;
+                }
+        }
+}
diff --git a/include/linux/pci.h b/include/linux/pci.h
index fb57c892b214..0f76d0f66365 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1510,6 +1510,7 @@ enum pci_fixup_pass {
 void pci_fixup_device(enum pci_fixup_pass pass, struct pci_dev *dev);
 struct pci_dev *pci_get_dma_source(struct pci_dev *dev);
 int pci_dev_specific_acs_enabled(struct pci_dev *dev, u16 acs_flags);
+void pci_dev_specific_enable_acs(struct pci_dev *dev);
 #else
 static inline void pci_fixup_device(enum pci_fixup_pass pass,
                                     struct pci_dev *dev) { }
@@ -1522,6 +1523,7 @@ static inline int pci_dev_specific_acs_enabled(struct pci_dev *dev,
 {
         return -ENOTTY;
 }
+static inline void pci_dev_specific_enable_acs(struct pci_dev *dev) { }
 #endif
 
 void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen);