MTD: MIPS: lantiq: verify that the NOR interface is available on falcon soc

When running on a FALC-ON SoC, we need to check the bootstrap options to see
if NOR is available.

Signed-off-by: John Crispin <blogic@openwrt.org>
Acked-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: linux-mtd@lists.infradead.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3815/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

drivers/mtd/maps/lantiq-flash.c

@@ -19,6 +19,7 @@
 #include <linux/mtd/cfi.h>
 #include <linux/platform_device.h>
 #include <linux/mtd/physmap.h>
+#include <linux/of.h>
 
 #include <lantiq_soc.h>
 
@@ -116,6 +117,12 @@ ltq_mtd_probe(struct platform_device *pdev)
 	struct cfi_private *cfi;
 	int err;
 
+	if (of_machine_is_compatible("lantiq,falcon") &&
+			(ltq_boot_select() != BS_FLASH)) {
+		dev_err(&pdev->dev, "invalid bootstrap options\n");
+		return -ENODEV;
+	}
+
 	ltq_mtd = kzalloc(sizeof(struct ltq_mtd), GFP_KERNEL);
 	platform_set_drvdata(pdev, ltq_mtd);