Add an implementation how to detect wakeup event for PCI. PCI device can
invoke PME, platform or PCIe native approach can collect the event and
report to OS. OS should identify exactly which device invokes PME as
several devices can share PME pin.
In platform approach (ACPI in this case), some BIOS give exact device which
invokes PME but others doesn't.
In PCIe native approach, if PME source device is a pcie endpoint, the device
is the exact PME source. If the device is root port or pcie-to-pci bridge,
we need scan the hierarchy under the device.
To identify PME source, the patch does:
1. if the source is a pci device, the device is the only source for PME
2. if the source is a bridge, scan the hierarchy under the bridge. Several
devices under the bridge could be the sources.
Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
---
drivers/pci/pci-driver.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++
drivers/pci/pci.h | 2 +
2 files changed, 79 insertions(+)
Index: linux/drivers/pci/pci-driver.c
===================================================================
--- linux.orig/drivers/pci/pci-driver.c 2009-08-24 10:50:12.000000000 +0800
+++ linux/drivers/pci/pci-driver.c 2009-08-24 15:42:49.000000000 +0800
@@ -17,6 +17,7 @@
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/cpu.h>
+#include <linux/pm_runtime.h>
#include "pci.h"
/*
@@ -570,6 +571,82 @@ static void pci_pm_complete(struct devic
drv->pm->complete(dev);
}
+/*
+ * Called when dev is suspected to invoke a wakeup event
+ * */
+static bool pci_pm_check_wakeup_event(struct pci_dev *pdev)
+{
+ int pme_pos = pdev->pm_cap;
+ u16 pmcsr;
+ bool spurious = false;
+
+ if (pme_pos == 0) {
+ /*
+ * Some USB devices haven't PME, but have specific registers to
+ * control wakeup
+ */
+ return false;
+ }
+
+ /* clear PME status and disable PME to avoid interrupt flood */
+ pci_read_config_word(pdev, pme_pos + PCI_PM_CTRL, &pmcsr);
+ if (!(pmcsr & PCI_PM_CTRL_PME_STATUS))
+ return false;
+ /* I see spurious PME here, just ignore it for now */
+ if (!(pmcsr & PCI_PM_CTRL_PME_ENABLE))
+ spurious = true;
+ else
+ pmcsr &= ~PCI_PM_CTRL_PME_ENABLE;
+ pmcsr |= PCI_PM_CTRL_PME_STATUS;
+ pci_write_config_word(pdev, pme_pos + PCI_PM_CTRL, pmcsr);
+
+ if (spurious)
+ return false;
+ return true;
+}
+
+/* @target is suspected to invoke a wakeup event. Return true if it's true */
+bool pci_pm_handle_wakeup_event(struct pci_dev *target)
+{
+ bool ret;
+ struct pci_dev *tmp = NULL;
+ int domain_nr, bus_start, bus_end;
+
+ /*
+ * @target could be a bridge or a device.
+ * if target is device, trust the device invokes PME. If target is a
+ * bridge, scan devices under the bridge and only trust device invokes
+ * PME which we can detect
+ **/
+ ret = pci_pm_check_wakeup_event(target);
+ if (!target->subordinate || (target->is_pcie &&
+ target->pcie_type != PCI_EXP_TYPE_ROOT_PORT &&
+ target->pcie_type != PCI_EXP_TYPE_PCI_BRIDGE)) {
+ /* always trust the device invokes PME even we can't detect */
+ pm_request_resume(&target->dev);
+ return true;
+ }
+
+ if (ret)
+ pm_request_resume(&target->dev);
+
+ /* scan devices under the bridge */
+ domain_nr = pci_domain_nr(target->bus);
+ bus_start = target->subordinate->secondary;
+ bus_end = target->subordinate->subordinate;
+ while ((tmp = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, tmp)) != NULL) {
+ if (pci_domain_nr(tmp->bus) == domain_nr &&
+ tmp->bus->number >= bus_start &&
+ tmp->bus->number <= bus_end) {
+ if (pci_pm_check_wakeup_event(tmp)) {
+ ret = true;
+ pm_request_resume(&tmp->dev);
+ }
+ }
+ }
+ return ret;
+}
+
#ifdef CONFIG_SUSPEND
static int pci_pm_suspend(struct device *dev)
Index: linux/drivers/pci/pci.h
===================================================================
--- linux.orig/drivers/pci/pci.h 2009-08-24 11:04:22.000000000 +0800
+++ linux/drivers/pci/pci.h 2009-08-24 11:05:24.000000000 +0800
@@ -83,6 +83,8 @@ static inline void pci_vpd_release(struc
dev->vpd->ops->release(dev);
}
+extern bool pci_pm_handle_wakeup_event(struct pci_dev *target);
+
/* PCI /proc functions */
#ifdef CONFIG_PROC_FS
extern int pci_proc_attach_device(struct pci_dev *dev);
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