remoteproc: xlnx: Add shutdown callback

In case of kexec call, each driver's shutdown callback is called. Handle
this call for rproc driver and shutdown/detach each core that was powered
on before. This is needed for proper Life Cycle Management of remote
processor. Otherwise on next linux boot, remote processor can't be
started due to bad refcount of power-domain managed by platform
management controller.

Signed-off-by: Tanmay Shah <tanmay.shah@amd.com>
Link: https://lore.kernel.org/r/20250620195728.3216935-1-tanmay.shah@amd.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

Author: tnmysh

drivers/remoteproc/xlnx_r5_remoteproc.c

@@ -1467,6 +1467,45 @@ static void zynqmp_r5_cluster_exit(void *data)
 	platform_set_drvdata(pdev, NULL);
 }
 
+/*
+ * zynqmp_r5_remoteproc_shutdown()
+ * Follow shutdown sequence in case of kexec call.
+ *
+ * @pdev: domain platform device for cluster
+ *
+ * Return: None.
+ */
+static void zynqmp_r5_remoteproc_shutdown(struct platform_device *pdev)
+{
+	const char *rproc_state_str = NULL;
+	struct zynqmp_r5_cluster *cluster;
+	struct zynqmp_r5_core *r5_core;
+	struct rproc *rproc;
+	int i, ret = 0;
+
+	cluster = platform_get_drvdata(pdev);
+
+	for (i = 0; i < cluster->core_count; i++) {
+		r5_core = cluster->r5_cores[i];
+		rproc = r5_core->rproc;
+
+		if (rproc->state == RPROC_RUNNING) {
+			ret = rproc_shutdown(rproc);
+			rproc_state_str = "shutdown";
+		} else if (rproc->state == RPROC_ATTACHED) {
+			ret = rproc_detach(rproc);
+			rproc_state_str = "detach";
+		} else {
+			ret = 0;
+		}
+
+		if (ret) {
+			dev_err(cluster->dev, "failed to %s rproc %d\n",
+				rproc_state_str, rproc->index);
+		}
+	}
+}
+
 /*
  * zynqmp_r5_remoteproc_probe()
  * parse device-tree, initialize hardware and allocate required resources
@@ -1528,6 +1567,7 @@ static struct platform_driver zynqmp_r5_remoteproc_driver = {
 		.name = "zynqmp_r5_remoteproc",
 		.of_match_table = zynqmp_r5_remoteproc_match,
 	},
+	.shutdown = zynqmp_r5_remoteproc_shutdown,
 };
 module_platform_driver(zynqmp_r5_remoteproc_driver);