devres: allow adding custom actions to the stack

Sometimes drivers need to execute one-off actions in their error handling
or device teardown paths. An example would be toggling a GPIO line to
reset the controlled device into predefined state.

To allow performing such actions when using managed resources let's allow
adding them to stack/group of devres resources.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
diff --git a/include/linux/device.h b/include/linux/device.h
index 86ef6ab..854b247 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -567,6 +567,10 @@
 void __iomem *devm_request_and_ioremap(struct device *dev,
 			struct resource *res);
 
+/* allows to add/remove a custom action to devres stack */
+int devm_add_action(struct device *dev, void (*action)(void *), void *data);
+void devm_remove_action(struct device *dev, void (*action)(void *), void *data);
+
 struct device_dma_parameters {
 	/*
 	 * a low level driver may set these to teach IOMMU code about