spi: bcm-qspi: return error if neither hif_mspi nor mspi is available

If neither a "hif_mspi" nor "mspi" resource is present, the driver will
just early exit in probe but still return success. Apart from not doing
anything meaningful, this would then also lead to a null pointer access
on removal, as platform_get_drvdata() would return NULL, which it would
then try to dereference when trying to unregister the spi master.

Fix this by unconditionally calling devm_ioremap_resource(), as it can
handle a NULL res and will then return a viable ERR_PTR() if we get one.

The "return 0;" was previously a "goto qspi_resource_err;" where then
ret was returned, but since ret was still initialized to 0 at this place
this was a valid conversion in 63c5395 ("spi: bcm-qspi: Fix
use-after-free on unbind"). The issue was not introduced by this commit,
only made more obvious.

Fixes: fa236a7 ("spi: bcm-qspi: Add Broadcom MSPI driver")
Signed-off-by: Jonas Gorski <[email protected]>
Reviewed-by: Kamal Dasu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: KanjiMonster

drivers/spi/spi-bcm-qspi.c

@@ -1543,13 +1543,9 @@ int bcm_qspi_probe(struct platform_device *pdev,
 		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
 						   "mspi");
 
-	if (res) {
-		qspi->base[MSPI]  = devm_ioremap_resource(dev, res);
-		if (IS_ERR(qspi->base[MSPI]))
-			return PTR_ERR(qspi->base[MSPI]);
-	} else {
-		return 0;
-	}
+	qspi->base[MSPI]  = devm_ioremap_resource(dev, res);
+	if (IS_ERR(qspi->base[MSPI]))
+		return PTR_ERR(qspi->base[MSPI]);
 
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "bspi");
 	if (res) {