remoteproc: Introducing function rproc_validate()

Add a new function to assert the general health of the remote
processor before handing it to the remoteproc core.
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Tested-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Link: https://lore.kernel.org/r/20200714195035.1426873-6-mathieu.poirier@linaro.orgSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/remoteproc/remoteproc_core.c

@@ -2043,6 +2043,43 @@ struct rproc *rproc_get_by_phandle(phandle phandle)
 #endif
 EXPORT_SYMBOL(rproc_get_by_phandle);
 
+static int rproc_validate(struct rproc *rproc)
+{
+	switch (rproc->state) {
+	case RPROC_OFFLINE:
+		/*
+		 * An offline processor without a start()
+		 * function makes no sense.
+		 */
+		if (!rproc->ops->start)
+			return -EINVAL;
+		break;
+	case RPROC_DETACHED:
+		/*
+		 * A remote processor in a detached state without an
+		 * attach() function makes not sense.
+		 */
+		if (!rproc->ops->attach)
+			return -EINVAL;
+		/*
+		 * When attaching to a remote processor the device memory
+		 * is already available and as such there is no need to have a
+		 * cached table.
+		 */
+		if (rproc->cached_table)
+			return -EINVAL;
+		break;
+	default:
+		/*
+		 * When adding a remote processor, the state of the device
+		 * can be offline or detached, nothing else.
+		 */
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 /**
  * rproc_add() - register a remote processor
  * @rproc: the remote processor handle to register
@@ -2072,6 +2109,10 @@ int rproc_add(struct rproc *rproc)
 	if (ret < 0)
 		return ret;
 
+	ret = rproc_validate(rproc);
+	if (ret < 0)
+		return ret;
+
 	dev_info(dev, "%s is available\n", rproc->name);
 
 	/* create debugfs entries */