From 8b46dc5cfa5ffea279aed0fc05dc4b1c39a51517 Mon Sep 17 00:00:00 2001
From: Mathieu Poirier <mathieu.poirier@linaro.org>
Date: Tue, 30 Jan 2024 07:48:49 -0800
Subject: remoteproc: Make rproc_get_by_phandle() work for clusters

Multi-cluster remoteproc designs typically have the following DT
declaration:

        remoteproc-cluster {
                compatible = "soc,remoteproc-cluster";

                core0: core0 {
                        compatible = "soc,remoteproc-core"
                        memory-region;
                        sram;
                };

                core1: core1 {
                        compatible = "soc,remoteproc-core"
                        memory-region;
                        sram;
                }
        };

A driver exists for the cluster rather than the individual cores
themselves so that operation mode and HW specific configurations
applicable to the cluster can be made.

Because the driver exists at the cluster level and not the individual
core level, function rproc_get_by_phandle() fails to return the
remoteproc associated with the phandled it is called for.

This patch enhances rproc_get_by_phandle() by looking for the cluster's
driver when the driver for the immediate remoteproc's parent is not
found.

Reported-by: Ben Levinsky <ben.levinsky@xilinx.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Co-developed-by: Tarak Reddy <tarak.reddy@amd.com>
Signed-off-by: Tarak Reddy <tarak.reddy@amd.com>
Co-developed-by: Tanmay Shah <tanmay.shah@amd.com>
Signed-off-by: Tanmay Shah <tanmay.shah@amd.com>
Link: https://lore.kernel.org/r/20240130154849.1018666-1-tanmay.shah@amd.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
---
 drivers/remoteproc/remoteproc_core.c | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

(limited to 'drivers/remoteproc')

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 695cce218e8c..f276956f2c5c 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -33,6 +33,7 @@
 #include <linux/idr.h>
 #include <linux/elf.h>
 #include <linux/crc32.h>
+#include <linux/of_platform.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/virtio_ids.h>
 #include <linux/virtio_ring.h>
@@ -2112,6 +2113,7 @@ EXPORT_SYMBOL(rproc_detach);
 struct rproc *rproc_get_by_phandle(phandle phandle)
 {
 	struct rproc *rproc = NULL, *r;
+	struct device_driver *driver;
 	struct device_node *np;
 
 	np = of_find_node_by_phandle(phandle);
@@ -2122,7 +2124,26 @@ struct rproc *rproc_get_by_phandle(phandle phandle)
 	list_for_each_entry_rcu(r, &rproc_list, node) {
 		if (r->dev.parent && device_match_of_node(r->dev.parent, np)) {
 			/* prevent underlying implementation from being removed */
-			if (!try_module_get(r->dev.parent->driver->owner)) {
+
+			/*
+			 * If the remoteproc's parent has a driver, the
+			 * remoteproc is not part of a cluster and we can use
+			 * that driver.
+			 */
+			driver = r->dev.parent->driver;
+
+			/*
+			 * If the remoteproc's parent does not have a driver,
+			 * look for the driver associated with the cluster.
+			 */
+			if (!driver) {
+				if (r->dev.parent->parent)
+					driver = r->dev.parent->parent->driver;
+				if (!driver)
+					break;
+			}
+
+			if (!try_module_get(driver->owner)) {
 				dev_err(&r->dev, "can't get owner\n");
 				break;
 			}
@@ -2533,7 +2554,11 @@ EXPORT_SYMBOL(rproc_free);
  */
 void rproc_put(struct rproc *rproc)
 {
-	module_put(rproc->dev.parent->driver->owner);
+	if (rproc->dev.parent->driver)
+		module_put(rproc->dev.parent->driver->owner);
+	else
+		module_put(rproc->dev.parent->parent->driver->owner);
+
 	put_device(&rproc->dev);
 }
 EXPORT_SYMBOL(rproc_put);
-- 
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