devm-helpers: Add resource managed version of work init

A few drivers which need a work-queue must cancel work at driver detach.
Some of those implement remove() solely for this purpose. Help drivers to
avoid unnecessary remove and error-branch implementation by adding managed
verision of work initialization. This will also help drivers to avoid
mixing manual and devm based unwinding when other resources are handled by
devm.

Signed-off-by: Matti Vaittinen <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: Hans de Goede <[e-mail]>
Link: https://lore.kernel.org/r/94ff417[e-mail]
Signed-off-by: Hans de Goede <[e-mail]>

include/linux/devm-helpers.h

···
 	return devm_add_action(dev, devm_delayed_work_drop, w);
 }
 
+static inline void devm_work_drop(void *res)
+{
+	cancel_work_sync(res);
+}
+
+/**
+ * devm_work_autocancel - Resource-managed work allocation
+ * @dev:	Device which lifetime work is bound to
+ * @w:		Work to be added (and automatically cancelled)
+ * @worker:	Worker function
+ *
+ * Initialize work which is automatically cancelled when driver is detached.
+ * A few drivers need to queue work which must be cancelled before driver
+ * is detached to avoid accessing removed resources.
+ * devm_work_autocancel() can be used to omit the explicit
+ * cancelleation when driver is detached.
+ */
+static inline int devm_work_autocancel(struct device *dev,
+				       struct work_struct *w,
+				       work_func_t worker)
+{
+	INIT_WORK(w, worker);
+	return devm_add_action(dev, devm_work_drop, w);
+}
+
 #endif