PCI: acpiphp: Do not use ACPI PCI subdriver mechanism

Previously the acpiphp driver registered itself as an ACPI PCI subdriver,
so its callbacks were invoked when creating/destroying PCI root
buses to manage ACPI-based PCI hotplug slots.  But it doesn't handle
P2P bridge hotplug events, so it will cause strange behaviour if there
are hotplug slots associated with a hot-removed P2P bridge.

This patch fixes this issue by:
1) Directly hooking into PCI core to update hotplug slot devices when
   creating/destroying PCI buses through:
	pci_{add|remove}_bus() -> acpi_pci_{add|remove}_bus()
2) Getting rid of unused ACPI PCI subdriver-related code

It also cleans up unused code in the acpiphp driver.

[bhelgaas: keep acpi_pci_add_bus() stub for CONFIG_ACPI=n]
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Yinghai Lu <yinghai@kernel.org>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Toshi Kani <toshi.kani@hp.com>

drivers/pci/hotplug/acpiphp.h

@@ -119,7 +119,6 @@ struct acpiphp_slot {
  */
 struct acpiphp_func {
 	struct acpiphp_slot *slot;	/* parent */
-	struct acpiphp_bridge *bridge;	/* Ejectable PCI-to-PCI bridge */
 
 	struct list_head sibling;
 	struct notifier_block nb;
@@ -176,8 +175,6 @@ extern int acpiphp_register_hotplug_slot(struct acpiphp_slot *slot);
 extern void acpiphp_unregister_hotplug_slot(struct acpiphp_slot *slot);
 
 /* acpiphp_glue.c */
-extern int acpiphp_glue_init (void);
-extern void acpiphp_glue_exit (void);
 typedef int (*acpiphp_callback)(struct acpiphp_slot *slot, void *data);
 
 extern int acpiphp_enable_slot (struct acpiphp_slot *slot);

drivers/pci/hotplug/acpiphp_core.c

@@ -37,6 +37,7 @@
 
 #include <linux/kernel.h>
 #include <linux/pci.h>
+#include <linux/pci-acpi.h>
 #include <linux/pci_hotplug.h>
 #include <linux/slab.h>
 #include <linux/smp.h>
@@ -354,19 +355,9 @@ void acpiphp_unregister_hotplug_slot(struct acpiphp_slot *acpiphp_slot)
 }
 
 
-static int __init acpiphp_init(void)
+void __init acpiphp_init(void)
 {
 	info(DRIVER_DESC " version: " DRIVER_VERSION "%s\n",
 		acpiphp_disabled ? ", disabled by user; please report a bug"
 				 : "");
-
-	if (acpi_pci_disabled || acpiphp_disabled)
-		return 0;
-
-	/* read all the ACPI info from the system */
-	/* initialize internal data structure etc. */
-	return acpiphp_glue_init();
 }
-
-
-module_init(acpiphp_init);