remoteproc: Introduce subdevices

A subdevice is an abstract entity that can be used to tie actions to the
booting and shutting down of a remote processor. The subdevice object is
expected to be embedded in concrete implementations, allowing for a
variety of use cases to be implemented.

Signed-off-by: Bjorn Andersson <[e-mail]>

drivers/remoteproc/remoteproc_core.c

···
 	return ret;
 }
 
+static int rproc_probe_subdevices(struct rproc *rproc)
+{
+	struct rproc_subdev *subdev;
+	int ret;
+
+	list_for_each_entry(subdev, &rproc->subdevs, node) {
+		ret = subdev->probe(subdev);
+		if (ret)
+			goto unroll_registration;
+	}
+
+	return 0;
+
+unroll_registration:
+	list_for_each_entry_continue_reverse(subdev, &rproc->subdevs, node)
+		subdev->remove(subdev);
+
+	return ret;
+}
+
+static void rproc_remove_subdevices(struct rproc *rproc)
+{
+	struct rproc_subdev *subdev;
+
+	list_for_each_entry(subdev, &rproc->subdevs, node)
+		subdev->remove(subdev);
+}
+
 /**
  * rproc_resource_cleanup() - clean up and free all acquired resources
  * @rproc: rproc handle
···
 		goto clean_up_resources;
 	}
 
+	/* probe any subdevices for the remote processor */
+	ret = rproc_probe_subdevices(rproc);
+	if (ret) {
+		dev_err(dev, "failed to probe subdevices for %s: %d\n",
+			rproc->name, ret);
+		goto stop_rproc;
+	}
+
 	rproc->state = RPROC_RUNNING;
 
 	dev_info(dev, "remote processor %s is now up\n", rproc->name);
 
 	return 0;
 
+stop_rproc:
+	rproc->ops->stop(rproc);
 clean_up_resources:
 	rproc_resource_cleanup(rproc);
 clean_up:
···
 	/* if the remote proc is still needed, bail out */
 	if (!atomic_dec_and_test(&rproc->power))
 		goto out;
+
+	/* remove any subdevices for the remote processor */
+	rproc_remove_subdevices(rproc);
 
 	/* power off the remote processor */
 	ret = rproc->ops->stop(rproc);
···
 	INIT_LIST_HEAD(&rproc->mappings);
 	INIT_LIST_HEAD(&rproc->traces);
 	INIT_LIST_HEAD(&rproc->rvdevs);
+	INIT_LIST_HEAD(&rproc->subdevs);
 
 	INIT_WORK(&rproc->crash_handler, rproc_crash_handler_work);
 	init_completion(&rproc->crash_comp);
···
 	return 0;
 }
 EXPORT_SYMBOL(rproc_del);
+
+/**
+ * rproc_add_subdev() - add a subdevice to a remoteproc
+ * @rproc: rproc handle to add the subdevice to
+ * @subdev: subdev handle to register
+ * @probe: function to call when the rproc boots
+ * @remove: function to call when the rproc shuts down
+ */
+void rproc_add_subdev(struct rproc *rproc,
+		      struct rproc_subdev *subdev,
+		      int (*probe)(struct rproc_subdev *subdev),
+		      void (*remove)(struct rproc_subdev *subdev))
+{
+	subdev->probe = probe;
+	subdev->remove = remove;
+
+	list_add_tail(&subdev->node, &rproc->subdevs);
+}
+EXPORT_SYMBOL(rproc_add_subdev);
+
+/**
+ * rproc_remove_subdev() - remove a subdevice from a remoteproc
+ * @rproc: rproc handle to remove the subdevice from
+ * @subdev: subdev handle, previously registered with rproc_add_subdev()
+ */
+void rproc_remove_subdev(struct rproc *rproc, struct rproc_subdev *subdev)
+{
+	list_del(&subdev->node);
+}
+EXPORT_SYMBOL(rproc_remove_subdev);
 
 /**
  * rproc_report_crash() - rproc crash reporter function

include/linux/remoteproc.h

···
  * @firmware_loading_complete: marks e/o asynchronous firmware loading
  * @bootaddr: address of first instruction to boot rproc with (optional)
  * @rvdevs: list of remote virtio devices
+ * @subdevs: list of subdevices, to following the running state
  * @notifyids: idr for dynamically assigning rproc-wide unique notify ids
  * @index: index of this rproc device
  * @crash_handler: workqueue for handling a crash
···
 	struct completion firmware_loading_complete;
 	u32 bootaddr;
 	struct list_head rvdevs;
+	struct list_head subdevs;
 	struct idr notifyids;
 	int index;
 	struct work_struct crash_handler;
···
 	struct resource_table *cached_table;
 	bool has_iommu;
 	bool auto_boot;
+};
+
+/**
+ * struct rproc_subdev - subdevice tied to a remoteproc
+ * @node: list node related to the rproc subdevs list
+ * @probe: probe function, called as the rproc is started
+ * @remove: remove function, called as the rproc is stopped
+ */
+struct rproc_subdev {
+	struct list_head node;
+
+	int (*probe)(struct rproc_subdev *subdev);
+	void (*remove)(struct rproc_subdev *subdev);
 };
 
 /* we currently support only two vrings per rvdev */
···
 
 	return rvdev->rproc;
 }
+
+void rproc_add_subdev(struct rproc *rproc,
+		      struct rproc_subdev *subdev,
+		      int (*probe)(struct rproc_subdev *subdev),
+		      void (*remove)(struct rproc_subdev *subdev));
+
+void rproc_remove_subdev(struct rproc *rproc, struct rproc_subdev *subdev);
 
 #endif /* REMOTEPROC_H */