driver core: auxiliary bus: Introduce dev_is_auxiliary()

Introduce dev_is_auxiliary() in analogy with dev_is_platform() to
facilitate subsequent changes.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/5079467.GXAFRqVoOG@rafael.j.wysocki

Author: rafaeljw

drivers/base/auxiliary.c

@@ -502,6 +502,16 @@ struct auxiliary_device *__devm_auxiliary_device_create(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(__devm_auxiliary_device_create);
 
+/**
+ * dev_is_auxiliary - check if the device is an auxiliary one
+ * @dev: device to check
+ */
+bool dev_is_auxiliary(struct device *dev)
+{
+	return dev->bus == &auxiliary_bus_type;
+}
+EXPORT_SYMBOL_GPL(dev_is_auxiliary);
+
 void __init auxiliary_bus_init(void)
 {
 	WARN_ON(bus_register(&auxiliary_bus_type));

include/linux/auxiliary_bus.h

@@ -271,6 +271,8 @@ struct auxiliary_device *__devm_auxiliary_device_create(struct device *dev,
 	__devm_auxiliary_device_create(dev, KBUILD_MODNAME, devname,  \
 				       platform_data, 0)
 
+bool dev_is_auxiliary(struct device *dev);
+
 /**
  * module_auxiliary_driver() - Helper macro for registering an auxiliary driver
  * @__auxiliary_driver: auxiliary driver struct