ACPI / hotplug / PCI: Make device_is_managed_by_native_pciehp() public

We're about to add runtime PM of hotplug ports, but we need to restrict it
to ports that are handled natively by the OS:  If they're handled by the
firmware (which is the case for Thunderbolt on non-Macs), things would
break if the OS put the ports into D3hot behind the firmware's back.

To determine if a hotplug port is handled natively, one has to walk up from
the port to the root bridge and check the cached _OSC Control Field for the
value of the "PCI Express Native Hot Plug control" bit.  There's already a
function to do that, device_is_managed_by_native_pciehp(), but it's private
to drivers/pci/hotplug/acpiphp_glue.c and only compiled in if
CONFIG_HOTPLUG_PCI_ACPI is enabled.

Make it public and move it to drivers/pci/pci-acpi.c, so that it is
available in the more general CONFIG_ACPI case.

The function contains a check if the device in question is a hotplug port
and returns false if it's not.  The caller we're going to add doesn't need
this as it only calls the function if it actually *is* a hotplug port.
Move the check out of the function into the single existing caller.

Rename it to pciehp_is_native() and add some kerneldoc and polish.

No functional change intended.

Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index b286a56..5ed2dca 100644 (file)
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -222,32 +222,6 @@ static void acpiphp_post_dock_fixup(struct acpi_device *adev)
        acpiphp_let_context_go(context);
 }
 
-/* Check whether the PCI device is managed by native PCIe hotplug driver */
-static bool device_is_managed_by_native_pciehp(struct pci_dev *pdev)
-{
-       acpi_handle tmp;
-       struct acpi_pci_root *root;
-
-       /* Check whether the PCIe port supports native PCIe hotplug */
-       if (!pdev->is_hotplug_bridge)
-               return false;
-
-       /*
-        * Check whether native PCIe hotplug has been enabled for
-        * this PCIe hierarchy.
-        */
-       tmp = acpi_find_root_bridge_handle(pdev);
-       if (!tmp)
-               return false;
-       root = acpi_pci_find_root(tmp);
-       if (!root)
-               return false;
-       if (!(root->osc_control_set & OSC_PCI_EXPRESS_NATIVE_HP_CONTROL))
-               return false;
-
-       return true;
-}
-
 /**
  * acpiphp_add_context - Add ACPIPHP context to an ACPI device object.
  * @handle: ACPI handle of the object to add a context to.
@@ -331,7 +305,7 @@ static acpi_status acpiphp_add_context(acpi_handle handle, u32 lvl, void *data,
         * expose slots to user space in those cases.
         */
        if ((acpi_pci_check_ejectable(pbus, handle) || is_dock_device(adev))
-           && !(pdev && device_is_managed_by_native_pciehp(pdev))) {
+           && !(pdev && pdev->is_hotplug_bridge && pciehp_is_native(pdev))) {
                unsigned long long sun;
                int retval;
 

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index d966d47..ed3daa8 100644 (file)
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -294,6 +294,30 @@ int pci_get_hp_params(struct pci_dev *dev, struct hotplug_params *hpp)
 EXPORT_SYMBOL_GPL(pci_get_hp_params);
 
 /**
+ * pciehp_is_native - Check whether a hotplug port is handled by the OS
+ * @pdev: Hotplug port to check
+ *
+ * Walk up from @pdev to the host bridge, obtain its cached _OSC Control Field
+ * and return the value of the "PCI Express Native Hot Plug control" bit.
+ * On failure to obtain the _OSC Control Field return %false.
+ */
+bool pciehp_is_native(struct pci_dev *pdev)
+{
+       struct acpi_pci_root *root;
+       acpi_handle handle;
+
+       handle = acpi_find_root_bridge_handle(pdev);
+       if (!handle)
+               return false;
+
+       root = acpi_pci_find_root(handle);
+       if (!root)
+               return false;
+
+       return root->osc_control_set & OSC_PCI_EXPRESS_NATIVE_HP_CONTROL;
+}
+
+/**
  * pci_acpi_wake_bus - Root bus wakeup notification fork function.
  * @work: Work item to handle.
  */

diff --git a/include/linux/pci_hotplug.h b/include/linux/pci_hotplug.h
index 8c78950..2e855af 100644 (file)
--- a/include/linux/pci_hotplug.h
+++ b/include/linux/pci_hotplug.h
@@ -176,6 +176,7 @@ struct hotplug_params {
 #ifdef CONFIG_ACPI
 #include <linux/acpi.h>
 int pci_get_hp_params(struct pci_dev *dev, struct hotplug_params *hpp);
+bool pciehp_is_native(struct pci_dev *pdev);
 int acpi_get_hp_hw_control_from_firmware(struct pci_dev *dev, u32 flags);
 int acpi_pci_check_ejectable(struct pci_bus *pbus, acpi_handle handle);
 int acpi_pci_detect_ejectable(acpi_handle handle);
@@ -185,5 +186,6 @@ static inline int pci_get_hp_params(struct pci_dev *dev,
 {
        return -ENODEV;
 }
+static inline bool pciehp_is_native(struct pci_dev *pdev) { return true; }
 #endif
 #endif