From a32285ed4ba970b868b7fb49b716d776f4410ef6 Mon Sep 17 00:00:00 2001
From: Hauke Mehrtens <hauke@hauke-m.de>
Date: Sat, 19 Mar 2016 16:52:46 +0100
Subject: [PATCH] MIPS: lantiq: add support for device tree file from boot
 loader

This fetches the device tree file like it is specified in the MIPS UHI
interface if one was found. This is also used when the device tree file
was appended to the kernel image with cat.
This code is copied from arch/mips/bmips/setup.c.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
---
 arch/mips/lantiq/prom.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

--- a/arch/mips/lantiq/prom.c
+++ b/arch/mips/lantiq/prom.c
@@ -65,6 +65,8 @@ static void __init prom_init_cmdline(voi
 
 void __init plat_mem_setup(void)
 {
+	void *dtb;
+
 	ioport_resource.start = IOPORT_RESOURCE_START;
 	ioport_resource.end = IOPORT_RESOURCE_END;
 	iomem_resource.start = IOMEM_RESOURCE_START;
@@ -72,11 +74,18 @@ void __init plat_mem_setup(void)
 
 	set_io_port_base((unsigned long) KSEG1);
 
+	if (fw_arg0 == -2) /* UHI interface */
+		dtb = (void *)fw_arg1;
+	else if (__dtb_start != __dtb_end)
+		dtb = (void *)__dtb_start;
+	else
+		panic("no dtb found");
+
 	/*
-	 * Load the builtin devicetree. This causes the chosen node to be
+	 * Load the devicetree. This causes the chosen node to be
 	 * parsed resulting in our memory appearing
 	 */
-	__dt_setup_arch(__dtb_start);
+	__dt_setup_arch(dtb);
 }
 
 void __init device_tree_init(void)
