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openrisc: enable passing of flattened device tree pointer

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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: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Signed-off-by: Jonas Bonn <jonas@southpole.se>
This commit is contained in:
Stefan Kristiansson 2011-11-10 16:38:29 +01:00 committed by Jonas Bonn
parent 2e1c958de4
commit dec830189e
2 changed files with 25 additions and 10 deletions
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17
arch/openrisc/kernel/head.S
View File

@ -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

18
arch/openrisc/kernel/setup.c
View File

@ -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)
{
early_init_devtree(__dtb_start);
printk(KERN_INFO "Compiled-in FDT at 0x%p\n", __dtb_start);
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 %p\n", __dtb_start);
}
}
static int __init openrisc_device_probe(void)