PCI: shpchp: Request SHPC control via _OSC when adding host bridge

The SHPC driver now must be builtin (it cannot be a module).  If it is
present, request SHPC control immediately when adding the ACPI host bridge.
This is similar to how we handle native PCIe hotplug via pciehp.

Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[bhelgaas: split to separate patch]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/pci_root.c

@@ -477,6 +477,9 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm)
 	if (IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))
 		control |= OSC_PCI_EXPRESS_NATIVE_HP_CONTROL;
 
+	if (IS_ENABLED(CONFIG_HOTPLUG_PCI_SHPC))
+		control |= OSC_PCI_SHPC_NATIVE_HP_CONTROL;
+
 	if (pci_aer_available()) {
 		if (aer_acpi_firmware_first())
 			dev_info(&device->dev,
@@ -903,6 +906,8 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
 	host_bridge = to_pci_host_bridge(bus->bridge);
 	if (!(root->osc_control_set & OSC_PCI_EXPRESS_NATIVE_HP_CONTROL))
 		host_bridge->native_pcie_hotplug = 0;
+	if (!(root->osc_control_set & OSC_PCI_SHPC_NATIVE_HP_CONTROL))
+		host_bridge->native_shpc_hotplug = 0;
 	if (!(root->osc_control_set & OSC_PCI_EXPRESS_AER_CONTROL))
 		host_bridge->native_aer = 0;
 	if (!(root->osc_control_set & OSC_PCI_EXPRESS_PME_CONTROL))

drivers/pci/probe.c

@@ -553,6 +553,7 @@ struct pci_host_bridge *pci_alloc_host_bridge(size_t priv)
 	 */
 	bridge->native_aer = 1;
 	bridge->native_pcie_hotplug = 1;
+	bridge->native_shpc_hotplug = 1;
 	bridge->native_pme = 1;
 
 	return bridge;

include/linux/pci.h

@@ -475,6 +475,7 @@ struct pci_host_bridge {
 	unsigned int	no_ext_tags:1;		/* No Extended Tags */
 	unsigned int	native_aer:1;		/* OS may use PCIe AER */
 	unsigned int	native_pcie_hotplug:1;	/* OS may use PCIe hotplug */
+	unsigned int	native_shpc_hotplug:1;	/* OS may use SHPC hotplug */
 	unsigned int	native_pme:1;		/* OS may use PCIe PME */
 	/* Resource alignment requirements */
 	resource_size_t (*align_resource)(struct pci_dev *dev,