[PATCH v3 1/5] remoteproc: Change rproc_shutdown() to return a status

[Suman Anna <s-anna@ti.com>]

The rproc_shutdown() function is currently not returning any
error code, and any failures within rproc_stop() are not passed
back to the users. Change the signature to return a success value
back to the callers.

The remoteproc sysfs and cdev interfaces are also updated to
return back this status to userspace.

Signed-off-by: Suman Anna <s-anna@ti.com>
---
v3:
 - New patch in place of v2 patch "remoteproc: Add support for detach-only 
   during shutdown",  
   https://patchwork.kernel.org/project/linux-remoteproc/patch/20210723220248.6554-2-s-anna@ti.com/

 Documentation/staging/remoteproc.rst  | 3 ++-
 drivers/remoteproc/remoteproc_cdev.c  | 2 +-
 drivers/remoteproc/remoteproc_core.c  | 9 ++++++---
 drivers/remoteproc/remoteproc_sysfs.c | 2 +-
 include/linux/remoteproc.h            | 2 +-
 5 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/Documentation/staging/remoteproc.rst b/Documentation/staging/remoteproc.rst
index 9cccd3dd6a4b..348ee7e508ac 100644
--- a/Documentation/staging/remoteproc.rst
+++ b/Documentation/staging/remoteproc.rst
@@ -49,13 +49,14 @@ might also consider using dev_archdata for this).
 
 ::
 
-  void rproc_shutdown(struct rproc *rproc)
+  int rproc_shutdown(struct rproc *rproc)
 
 Power off a remote processor (previously booted with rproc_boot()).
 In case @rproc is still being used by an additional user(s), then
 this function will just decrement the power refcount and exit,
 without really powering off the device.
 
+Returns 0 on success, and an appropriate error value otherwise.
 Every call to rproc_boot() must (eventually) be accompanied by a call
 to rproc_shutdown(). Calling rproc_shutdown() redundantly is a bug.
 
diff --git a/drivers/remoteproc/remoteproc_cdev.c b/drivers/remoteproc/remoteproc_cdev.c
index 4ad98b0b8caa..906ff3c4dfdd 100644
--- a/drivers/remoteproc/remoteproc_cdev.c
+++ b/drivers/remoteproc/remoteproc_cdev.c
@@ -42,7 +42,7 @@ static ssize_t rproc_cdev_write(struct file *filp, const char __user *buf, size_
 		    rproc->state != RPROC_ATTACHED)
 			return -EINVAL;
 
-		rproc_shutdown(rproc);
+		ret = rproc_shutdown(rproc);
 	} else if (!strncmp(cmd, "detach", len)) {
 		if (rproc->state != RPROC_ATTACHED)
 			return -EINVAL;
diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 69f51acf235e..c510125769b9 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -2061,16 +2061,18 @@ EXPORT_SYMBOL(rproc_boot);
  *   which means that the @rproc handle stays valid even after rproc_shutdown()
  *   returns, and users can still use it with a subsequent rproc_boot(), if
  *   needed.
+ *
+ * Return: 0 on success, and an appropriate error value otherwise
  */
-void rproc_shutdown(struct rproc *rproc)
+int rproc_shutdown(struct rproc *rproc)
 {
 	struct device *dev = &rproc->dev;
-	int ret;
+	int ret = 0;
 
 	ret = mutex_lock_interruptible(&rproc->lock);
 	if (ret) {
 		dev_err(dev, "can't lock rproc %s: %d\n", rproc->name, ret);
-		return;
+		return ret;
 	}
 
 	/* if the remote proc is still needed, bail out */
@@ -2097,6 +2099,7 @@ void rproc_shutdown(struct rproc *rproc)
 	rproc->table_ptr = NULL;
 out:
 	mutex_unlock(&rproc->lock);
+	return ret;
 }
 EXPORT_SYMBOL(rproc_shutdown);
 
diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
index ea8b89f97d7b..645c70c8109b 100644
--- a/drivers/remoteproc/remoteproc_sysfs.c
+++ b/drivers/remoteproc/remoteproc_sysfs.c
@@ -206,7 +206,7 @@ static ssize_t state_store(struct device *dev,
 		    rproc->state != RPROC_ATTACHED)
 			return -EINVAL;
 
-		rproc_shutdown(rproc);
+		ret = rproc_shutdown(rproc);
 	} else if (sysfs_streq(buf, "detach")) {
 		if (rproc->state != RPROC_ATTACHED)
 			return -EINVAL;
diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index e0600e1e5c17..cfc0c95c95b2 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -669,7 +669,7 @@ rproc_of_resm_mem_entry_init(struct device *dev, u32 of_resm_idx, size_t len,
 			     u32 da, const char *name, ...);
 
 int rproc_boot(struct rproc *rproc);
-void rproc_shutdown(struct rproc *rproc);
+int rproc_shutdown(struct rproc *rproc);
 int rproc_detach(struct rproc *rproc);
 int rproc_set_firmware(struct rproc *rproc, const char *fw_name);
 void rproc_report_crash(struct rproc *rproc, enum rproc_crash_type type);
-- 
2.32.0