PCI / ACPI / PM: Platform support for PCI PME wake-up

Although the majority of PCI devices can generate PMEs that in
principle may be used to wake up devices suspended at run time,
platform support is generally necessary to convert PMEs into wake-up
events that can be delivered to the kernel.  If ACPI is used for this
purpose, PME signals generated by a PCI device will trigger the ACPI
GPE associated with the device to generate an ACPI wake-up event that
we can set up a handler for, provided that everything is configured
correctly.

Unfortunately, the subset of PCI devices that have GPEs associated
with them is quite limited.  The devices without dedicated GPEs have
to rely on the GPEs associated with other devices (in the majority of
cases their upstream bridges and, possibly, the root bridge) to
generate ACPI wake-up events in response to PME signals from them.

Add ACPI platform support for PCI PME wake-up:
o Add a framework making is possible to use ACPI system notify
  handlers for run-time PM.
o Add new PCI platform callback ->run_wake() to struct
  pci_platform_pm_ops allowing us to enable/disable the platform to
  generate wake-up events for given device.  Implemet this callback
  for the ACPI platform.
o Define ACPI wake-up handlers for PCI devices and PCI root buses and
  make the PCI-ACPI binding code register wake-up notifiers for all
  PCI devices present in the ACPI tables.
o Add function pci_dev_run_wake() which can be used by PCI drivers to
  check if given device is capable of generating wake-up events at
  run time.

Developed in cooperation with Matthew Garrett <mjg@redhat.com>.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 67 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 5723446544fd..df55a2f351b3 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -20,6 +20,7 @@
 #include <linux/pm_wakeup.h>
 #include <linux/interrupt.h>
 #include <linux/device.h>
+#include <linux/pm_runtime.h>
 #include <asm/setup.h>
 #include "pci.h"
 
@@ -462,6 +463,12 @@ static inline int platform_pci_sleep_wake(struct pci_dev *dev, bool enable)
                         pci_platform_pm->sleep_wake(dev, enable) : -ENODEV;
 }
 
+static inline int platform_pci_run_wake(struct pci_dev *dev, bool enable)
+{
+        return pci_platform_pm ?
+                        pci_platform_pm->run_wake(dev, enable) : -ENODEV;
+}
+
 /**
  * pci_raw_set_power_state - Use PCI PM registers to set the power state of
  *                           given PCI device
@@ -1230,6 +1237,31 @@ bool pci_check_pme_status(struct pci_dev *dev)
 }
 
 /**
+ * pci_pme_wakeup - Wake up a PCI device if its PME Status bit is set.
+ * @dev: Device to handle.
+ * @ign: Ignored.
+ *
+ * Check if @dev has generated PME and queue a resume request for it in that
+ * case.
+ */
+static int pci_pme_wakeup(struct pci_dev *dev, void *ign)
+{
+        if (pci_check_pme_status(dev))
+                pm_request_resume(&dev->dev);
+        return 0;
+}
+
+/**
+ * pci_pme_wakeup_bus - Walk given bus and wake up devices on it, if necessary.
+ * @bus: Top bus of the subtree to walk.
+ */
+void pci_pme_wakeup_bus(struct pci_bus *bus)
+{
+        if (bus)
+                pci_walk_bus(bus, pci_pme_wakeup, NULL);
+}
+
+/**
  * pci_pme_capable - check the capability of PCI device to generate PME#
  * @dev: PCI device to handle.
  * @state: PCI state from which device will issue PME#.
@@ -1434,6 +1466,41 @@ int pci_back_from_sleep(struct pci_dev *dev)
 }
 
 /**
+ * pci_dev_run_wake - Check if device can generate run-time wake-up events.
+ * @dev: Device to check.
+ *
+ * Return true if the device itself is cabable of generating wake-up events
+ * (through the platform or using the native PCIe PME) or if the device supports
+ * PME and one of its upstream bridges can generate wake-up events.
+ */
+bool pci_dev_run_wake(struct pci_dev *dev)
+{
+        struct pci_bus *bus = dev->bus;
+
+        if (device_run_wake(&dev->dev))
+                return true;
+
+        if (!dev->pme_support)
+                return false;
+
+        while (bus->parent) {
+                struct pci_dev *bridge = bus->self;
+
+                if (device_run_wake(&bridge->dev))
+                        return true;
+
+                bus = bus->parent;
+        }
+
+        /* We have reached the root bus. */
+        if (bus->bridge)
+                return device_run_wake(bus->bridge);
+
+        return false;
+}
+EXPORT_SYMBOL_GPL(pci_dev_run_wake);
+
+/**
  * pci_pm_init - Initialize PM functions of given PCI device
  * @dev: PCI device to handle.
  */