ACPI / hotplug: Introduce user space interface for hotplug profiles

Introduce user space interface for manipulating hotplug profiles
associated with ACPI scan handlers.

The interface consists of sysfs directories under
/sys/firmware/acpi/hotplug/, one for each hotplug profile, containing
an attribute allowing user space to manipulate the enabled field of
the corresponding profile.  Namely, switching the enabled attribute
from '0' to '1' will cause the common hotplug notify handler to be
installed for all ACPI namespace objects representing devices matching
the scan handler associated with the given hotplug profile (and
analogously for the converse switch).

Drivers willing to use the new user space interface should add their
ACPI scan handlers with the help of new funtion
acpi_scan_add_handler_with_hotplug().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Tested-by: Toshi Kani <toshi.kani@hp.com>
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 3c94a73..c708e4b 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -42,6 +42,12 @@
 static inline void acpi_container_init(void) {}
 #endif
 
+void acpi_sysfs_add_hotplug_profile(struct acpi_hotplug_profile *hotplug,
+				    const char *name);
+int acpi_scan_add_handler_with_hotplug(struct acpi_scan_handler *handler,
+				       const char *hotplug_profile_name);
+void acpi_scan_hotplug_enabled(struct acpi_hotplug_profile *hotplug, bool val);
+
 #ifdef CONFIG_DEBUG_FS
 extern struct dentry *acpi_debugfs_dir;
 int acpi_debugfs_init(void);