mtd: hyperbus: Make hyperbus_unregister_device() return void

The only thing that could theoretically fail in that function is
mtd_device_unregister(). However it's not supposed to fail and when
used correctly it doesn't. So wail loudly if it does anyhow.

This matches how other drivers (e.g. nand/raw/nandsim.c) use
mtd_device_unregister().

This is a preparation for making platform remove callbacks return void.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220603210758.148493-2-u.kleine-koenig@pengutronix.de

drivers/mtd/hyperbus/hbmc-am654.c

@@ -233,16 +233,16 @@ static int am654_hbmc_remove(struct platform_device *pdev)
 {
 	struct am654_hbmc_priv *priv = platform_get_drvdata(pdev);
 	struct am654_hbmc_device_priv *dev_priv = priv->hbdev.priv;
-	int ret;
 
-	ret = hyperbus_unregister_device(&priv->hbdev);
+	hyperbus_unregister_device(&priv->hbdev);
+
 	if (priv->mux_ctrl)
 		mux_control_deselect(priv->mux_ctrl);
 
 	if (dev_priv->rx_chan)
 		dma_release_channel(dev_priv->rx_chan);
 
-	return ret;
+	return 0;
 }
 
 static const struct of_device_id am654_hbmc_dt_ids[] = {

drivers/mtd/hyperbus/hyperbus-core.c

@@ -126,16 +126,12 @@ int hyperbus_register_device(struct hyperbus_device *hbdev)
 }
 EXPORT_SYMBOL_GPL(hyperbus_register_device);
 
-int hyperbus_unregister_device(struct hyperbus_device *hbdev)
+void hyperbus_unregister_device(struct hyperbus_device *hbdev)
 {
-	int ret = 0;
-
 	if (hbdev && hbdev->mtd) {
-		ret = mtd_device_unregister(hbdev->mtd);
+		WARN_ON(mtd_device_unregister(hbdev->mtd));
 		map_destroy(hbdev->mtd);
 	}
-
-	return ret;
 }
 EXPORT_SYMBOL_GPL(hyperbus_unregister_device);
 

drivers/mtd/hyperbus/rpc-if.c

@@ -153,11 +153,12 @@ static int rpcif_hb_probe(struct platform_device *pdev)
 static int rpcif_hb_remove(struct platform_device *pdev)
 {
 	struct rpcif_hyperbus *hyperbus = platform_get_drvdata(pdev);
-	int error = hyperbus_unregister_device(&hyperbus->hbdev);
+
+	hyperbus_unregister_device(&hyperbus->hbdev);
 
 	rpcif_disable_rpm(&hyperbus->rpc);
 
-	return error;
+	return 0;
 }
 
 static struct platform_driver rpcif_platform_driver = {

include/linux/mtd/hyperbus.h

@@ -89,9 +89,7 @@ int hyperbus_register_device(struct hyperbus_device *hbdev);
 /**
  * hyperbus_unregister_device - deregister HyperBus slave memory device
  * @hbdev: hyperbus_device to be unregistered
- *
- * Return: 0 for success, others for failure.
  */
-int hyperbus_unregister_device(struct hyperbus_device *hbdev);
+void hyperbus_unregister_device(struct hyperbus_device *hbdev);
 
 #endif /* __LINUX_MTD_HYPERBUS_H__ */