PCI/PM: Fix proc config reg access for D3cold and bridge suspending

In https://bugzilla.kernel.org/show_bug.cgi?id=48981
Peter reported that /proc/bus/pci/??/??.? does not work for 3.6.
This is because the device configuration space registers are
not accessible if the corresponding parent bridge is suspended or
the device is put into D3cold state.

This is the same as /sys/bus/pci/devices/0000:??:??.?/config access
issue.  So the function used to solve sysfs issue is used to solve
this issue.

This patch moves pci_config_pm_runtime_get()/_put() from pci/pci-sysfs.c
to pci/pci.c and makes them extern so they can be used by both the
sysfs and proc paths.

[bhelgaas: changelog, references, reporters]
Reference: https://bugzilla.kernel.org/show_bug.cgi?id=48981
Reference: https://bugzilla.kernel.org/show_bug.cgi?id=49031
Reported-by: Forrest Loomis <cybercyst@gmail.com>
Reported-by: Peter <lekensteyn@gmail.com>
Reported-by: Micael Dias <kam1kaz3@gmail.com>
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
CC: stable@vger.kernel.org		# v3.6+

1 files changed, 32 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 54858838f098..aabf64798bda 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1858,6 +1858,38 @@ bool pci_dev_run_wake(struct pci_dev *dev)
 }
 EXPORT_SYMBOL_GPL(pci_dev_run_wake);
 
+void pci_config_pm_runtime_get(struct pci_dev *pdev)
+{
+        struct device *dev = &pdev->dev;
+        struct device *parent = dev->parent;
+
+        if (parent)
+                pm_runtime_get_sync(parent);
+        pm_runtime_get_noresume(dev);
+        /*
+         * pdev->current_state is set to PCI_D3cold during suspending,
+         * so wait until suspending completes
+         */
+        pm_runtime_barrier(dev);
+        /*
+         * Only need to resume devices in D3cold, because config
+         * registers are still accessible for devices suspended but
+         * not in D3cold.
+         */
+        if (pdev->current_state == PCI_D3cold)
+                pm_runtime_resume(dev);
+}
+
+void pci_config_pm_runtime_put(struct pci_dev *pdev)
+{
+        struct device *dev = &pdev->dev;
+        struct device *parent = dev->parent;
+
+        pm_runtime_put(dev);
+        if (parent)
+                pm_runtime_put_sync(parent);
+}
+
 /**
  * pci_pm_init - Initialize PM functions of given PCI device
  * @dev: PCI device to handle.