[PATCH v4 3/9] remoteproc: Introducing function rproc_attach()

[Mathieu Poirier]

Introducing function rproc_attach() to enact the same actions as
rproc_start(), but without the steps related to the handling of
a firmware image.  That way we can properly deal with scenarios
where the remoteproc core needs to attach with a remote processsor
that has been booted by another entity.

Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
---
 drivers/remoteproc/remoteproc_core.c | 42 ++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 9f04c30c4aaf..0b323f6b554b 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -1370,6 +1370,48 @@ static int rproc_start(struct rproc *rproc, const struct firmware *fw)
 	return ret;
 }
 
+static int __maybe_unused rproc_attach(struct rproc *rproc)
+{
+	struct device *dev = &rproc->dev;
+	int ret;
+
+	ret = rproc_prepare_subdevices(rproc);
+	if (ret) {
+		dev_err(dev, "failed to prepare subdevices for %s: %d\n",
+			rproc->name, ret);
+		goto out;
+	}
+
+	/* Attach to the remote processor */
+	ret = rproc_attach_device(rproc);
+	if (ret) {
+		dev_err(dev, "can't attach to rproc %s: %d\n",
+			rproc->name, ret);
+		goto unprepare_subdevices;
+	}
+
+	/* Start any subdevices for the remote processor */
+	ret = rproc_start_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 attached\n", rproc->name);
+
+	return 0;
+
+stop_rproc:
+	rproc->ops->stop(rproc);
+unprepare_subdevices:
+	rproc_unprepare_subdevices(rproc);
+out:
+	return ret;
+}
+
 /*
  * take a firmware and boot a remote processor with it.
  */
-- 
2.20.1