From 437eb7bf7b28472f8b7689e166dc1dd691367121 Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Fri, 28 Oct 2016 10:52:06 +0200 Subject: ACPI / hotplug / PCI: Make device_is_managed_by_native_pciehp() public We're about to add runtime PM of hotplug ports, but we need to restrict it to ports that are handled natively by the OS: If they're handled by the firmware (which is the case for Thunderbolt on non-Macs), things would break if the OS put the ports into D3hot behind the firmware's back. To determine if a hotplug port is handled natively, one has to walk up from the port to the root bridge and check the cached _OSC Control Field for the value of the "PCI Express Native Hot Plug control" bit. There's already a function to do that, device_is_managed_by_native_pciehp(), but it's private to drivers/pci/hotplug/acpiphp_glue.c and only compiled in if CONFIG_HOTPLUG_PCI_ACPI is enabled. Make it public and move it to drivers/pci/pci-acpi.c, so that it is available in the more general CONFIG_ACPI case. The function contains a check if the device in question is a hotplug port and returns false if it's not. The caller we're going to add doesn't need this as it only calls the function if it actually *is* a hotplug port. Move the check out of the function into the single existing caller. Rename it to pciehp_is_native() and add some kerneldoc and polish. No functional change intended. Tested-by: Mika Westerberg Signed-off-by: Lukas Wunner Signed-off-by: Bjorn Helgaas Reviewed-by: Rafael J. Wysocki --- drivers/pci/pci-acpi.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'drivers/pci/pci-acpi.c') diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c index d966d47c9e80..ed3daa8e7658 100644 --- a/drivers/pci/pci-acpi.c +++ b/drivers/pci/pci-acpi.c @@ -293,6 +293,30 @@ int pci_get_hp_params(struct pci_dev *dev, struct hotplug_params *hpp) } EXPORT_SYMBOL_GPL(pci_get_hp_params); +/** + * pciehp_is_native - Check whether a hotplug port is handled by the OS + * @pdev: Hotplug port to check + * + * Walk up from @pdev to the host bridge, obtain its cached _OSC Control Field + * and return the value of the "PCI Express Native Hot Plug control" bit. + * On failure to obtain the _OSC Control Field return %false. + */ +bool pciehp_is_native(struct pci_dev *pdev) +{ + struct acpi_pci_root *root; + acpi_handle handle; + + handle = acpi_find_root_bridge_handle(pdev); + if (!handle) + return false; + + root = acpi_pci_find_root(handle); + if (!root) + return false; + + return root->osc_control_set & OSC_PCI_EXPRESS_NATIVE_HP_CONTROL; +} + /** * pci_acpi_wake_bus - Root bus wakeup notification fork function. * @work: Work item to handle. -- cgit v1.2.3