PCI PM: Add function for checking PME status of devices

Add function pci_check_pme_status() that will check the PME status
bit of given device and clear it along with the PME enable bit.  It
will be necessary for PCI run-time power management.

Based on a patch from Shaohua Li <shaohua.li@intel.com>

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

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 1f9be53..5723446 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1195,6 +1195,41 @@ int pci_set_pcie_reset_state(struct pci_dev *dev, enum pcie_reset_state state)
 }
 
 /**
+ * pci_check_pme_status - Check if given device has generated PME.
+ * @dev: Device to check.
+ *
+ * Check the PME status of the device and if set, clear it and clear PME enable
+ * (if set).  Return 'true' if PME status and PME enable were both set or
+ * 'false' otherwise.
+ */
+bool pci_check_pme_status(struct pci_dev *dev)
+{
+       int pmcsr_pos;
+       u16 pmcsr;
+       bool ret = false;
+
+       if (!dev->pm_cap)
+               return false;
+
+       pmcsr_pos = dev->pm_cap + PCI_PM_CTRL;
+       pci_read_config_word(dev, pmcsr_pos, &pmcsr);
+       if (!(pmcsr & PCI_PM_CTRL_PME_STATUS))
+               return false;
+
+       /* Clear PME status. */
+       pmcsr |= PCI_PM_CTRL_PME_STATUS;
+       if (pmcsr & PCI_PM_CTRL_PME_ENABLE) {
+               /* Disable PME to avoid interrupt flood. */
+               pmcsr &= ~PCI_PM_CTRL_PME_ENABLE;
+               ret = true;
+       }
+
+       pci_write_config_word(dev, pmcsr_pos, pmcsr);
+
+       return ret;
+}
+
+/**
  * 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#.

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 5d169bc..b95b0a0 100644 (file)
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -49,6 +49,7 @@ struct pci_platform_pm_ops {
 extern int pci_set_platform_pm(struct pci_platform_pm_ops *ops);
 extern void pci_update_current_state(struct pci_dev *dev, pci_power_t state);
 extern void pci_disable_enabled_device(struct pci_dev *dev);
+extern bool pci_check_pme_status(struct pci_dev *dev);
 extern void pci_pm_init(struct pci_dev *dev);
 extern void platform_pci_wakeup_init(struct pci_dev *dev);
 extern void pci_allocate_cap_save_buffers(struct pci_dev *dev);