MIPS: Create a helper function for DT setup

A couple of platforms register two buses and call of_platform_populate().
Move this into a common function to reduce duplication.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: mbizon@freebox.fr
Cc: jogo@openwrt.org
Cc: jfraser@broadcom.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8167/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/prom.c

@@ -16,6 +16,7 @@
 #include <linux/debugfs.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
+#include <linux/of_platform.h>
 
 #include <asm/page.h>
 #include <asm/prom.h>
@@ -54,4 +55,21 @@ void __init __dt_setup_arch(void *bph)
 
 	mips_set_machine_name(of_flat_dt_get_machine_name());
 }
+
+int __init __dt_register_buses(const char *bus0, const char *bus1)
+{
+	static struct of_device_id of_ids[3];
+
+	if (!of_have_populated_dt())
+		panic("device tree not present");
+
+	strlcpy(of_ids[0].compatible, bus0, sizeof(of_ids[0].compatible));
+	strlcpy(of_ids[1].compatible, bus1, sizeof(of_ids[1].compatible));
+
+	if (of_platform_populate(NULL, of_ids, NULL, NULL))
+		panic("failed to populate DT");
+
+	return 0;
+}
+
 #endif