On Wednesday 19 August 2009, Shaohua Li wrote:
> Add an implementation how to detect wakeup event for PCI bus level. PCI device
> can invoke PME and platform or PCIe native approach can collect the PME and
> reports to OS. OS should identify exactly which device invokes PME as several
> devices can share interrupts.
>
> 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 source.
>
>
> ---
> drivers/pci/pci-driver.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 90 insertions(+)
>
> Index: linux/drivers/pci/pci-driver.c
> ===================================================================
> --- linux.orig/drivers/pci/pci-driver.c 2009-08-19 13:43:18.000000000 +0800
> +++ linux/drivers/pci/pci-driver.c 2009-08-19 13:50:29.000000000 +0800
> @@ -570,6 +570,95 @@ static void pci_pm_complete(struct devic
> drv->pm->complete(dev);
> }
>
> +/*
> + * Called when dev is suspected to invoke a wakeup event
> + * */
> +static bool pci_handle_one_wakeup_event(struct pci_dev *pdev)
> +{
> + int pme_pos = pdev->pm_cap;
> + struct pci_driver *drv = pdev->driver;
> + u16 pmcsr;
> + bool spurious = false;
> +
> + if (pme_pos == 0) {
> + /*
> + * Some USB devices haven't PME, but have specific registers to
> + * control wakeup
> + */
> + goto out;
> + }
> +
> + /* 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;
> +out:
> + if (drv && drv->driver.pm && drv->driver.pm->wakeup_event)
> + return drv->driver.pm->wakeup_event(&pdev->dev);
> + return false;
> +}
> +
> +static bool pci_pm_wakeup_event(struct device *dev)
> +{
> + bool ret;
> + struct pci_dev *tmp = NULL, *target = to_pci_dev(dev);
> + int domain_nr, bus_start, bus_end;
> +
> + /*
> + * @target could be a bridge or a device.
> + * PCIe native PME case:
> + * @target is device - @target must be the exact device invoking PME
> + * @target is a root port or pcie-pci bridge - should scan legacy pci
> + * devices under the bridge
> + * ACPI GPE case:
> + * @target is device - AML code could clear PME status before this
> + * routine is called, so we can't detect if @target invokes PME.
> + * Let's trust AML code
> + * @target is bridge - scan devices under the bridge
> + * So: if target is device, trust the device invokes PME. If target is
> + * bridge, scan devices under the bridge and only trust device invokes
> + * PME which we can detect
> + **/
> + ret = pci_handle_one_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 */
> + device_receive_wakeup_event(&target->dev);
How's that thing defined? We want to call pm_request_resume() at this point.
> + return true;
> + }
> +
> + if (ret)
> + device_receive_wakeup_event(&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_handle_one_wakeup_event(tmp)) {
> + ret = true;
> + device_receive_wakeup_event(&tmp->dev);
And here.
> + }
> + }
> + }
> + return ret;
> +}
> +
> #ifdef CONFIG_SUSPEND
>
> static int pci_pm_suspend(struct device *dev)
> @@ -925,6 +1014,7 @@ struct dev_pm_ops pci_dev_pm_ops = {
> .thaw_noirq = pci_pm_thaw_noirq,
> .poweroff_noirq = pci_pm_poweroff_noirq,
> .restore_noirq = pci_pm_restore_noirq,
> + .wakeup_event = pci_pm_wakeup_event,
Please don't do that.
> };
>
> #define PCI_PM_OPS_PTR (&pci_dev_pm_ops)
Best,
Rafael
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