Commit dec83018 authored by Stefan Kristiansson's avatar Stefan Kristiansson Committed by Jonas Bonn
Browse files

openrisc: enable passing of flattened device tree pointer 



This patch enables passing a fdt pointer to the kernel.

This makes for the kernel parameter API:

void kernel(unsigned int fdt);

which, in accordance with the OpenRISC ABI results in:
r3 = pointer to fdt

Signed-off-by: default avatarStefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Signed-off-by: default avatarJonas Bonn <jonas@southpole.se>
parent 2e1c958d

arch/openrisc/kernel/head.S

+16 −1
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <asm/cache.h>

#include <asm/spr_defs.h>

#include <asm/asm-offsets.h>

#include <linux/of_fdt.h>



#define tophys(rd,rs)				\

	l.movhi	rd,hi(-KERNELBASE)		;\
@@ -440,6 +441,9 @@ _dispatch_do_ipage_fault: 
	__HEAD

	.global _start

_start:

	/* save kernel parameters */

	l.or	r25,r0,r3	/* pointer to fdt */



	/*

	 * ensure a deterministic start

	 */
@@ -471,7 +475,6 @@ _start: 
	CLEAR_GPR(r22)

	CLEAR_GPR(r23)

	CLEAR_GPR(r24)

	CLEAR_GPR(r25)

	CLEAR_GPR(r26)

	CLEAR_GPR(r27)

	CLEAR_GPR(r28)
@@ -565,6 +568,18 @@ enable_mmu: 
	// reset the simulation counters

	l.nop 5



	/* check fdt header magic word */

	l.lwz	r3,0(r25)	/* load magic from fdt into r3 */

	l.movhi	r4,hi(OF_DT_HEADER)

	l.ori	r4,r4,lo(OF_DT_HEADER)

	l.sfeq	r3,r4

	l.bf	_fdt_found

	 l.nop

	/* magic number mismatch, set fdt pointer to null */

	l.or	r25,r0,r0

_fdt_found:

	/* pass fdt pointer to or32_early_setup in r3 */

	l.or	r3,r0,r25

	LOAD_SYMBOL_2_GPR(r24, or32_early_setup)

	l.jalr r24

	 l.nop

arch/openrisc/kernel/setup.c

+9 −9
Original line number Diff line number Diff line
@@ -207,18 +207,18 @@ void __init setup_cpuinfo(void) 
 * Handles the pointer to the device tree that this kernel is to use

 * for establishing the available platform devices.

 *

 * For now, this is limited to using the built-in device tree.  In the future,

 * it is intended that this function will take a pointer to the device tree

 * that is potentially built-in, but potentially also passed in by the

 * bootloader, or discovered by some equally clever means...

 * Falls back on built-in device tree in case null pointer is passed.

 */



void __init or32_early_setup(void)

void __init or32_early_setup(unsigned int fdt)

{



	if (fdt) {

		early_init_devtree((void*) fdt);

		printk(KERN_INFO "FDT at 0x%08x\n", fdt);

	} else {

		early_init_devtree(__dtb_start);



	printk(KERN_INFO "Compiled-in FDT at 0x%p\n", __dtb_start);

		printk(KERN_INFO "Compiled-in FDT at %p\n", __dtb_start);

	}

}



static int __init openrisc_device_probe(void)