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authorStefan Kristiansson <stefan.kristiansson@saunalahti.fi>2011-11-10 16:38:29 +0100
committerJonas Bonn <jonas@southpole.se>2012-02-17 09:55:22 +0100
commitdec830189e1e192a80f574243a2dc31bdc1c4fc5 (patch)
tree864ae5fd9b3975805195eb2b0396d80e6a408425 /arch/openrisc/kernel
parent2e1c958de4e22b6badc13dba1a0ebaa5aa798664 (diff)
downloadlinux-dec830189e1e192a80f574243a2dc31bdc1c4fc5.tar.gz
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: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> Signed-off-by: Jonas Bonn <jonas@southpole.se>
Diffstat (limited to 'arch/openrisc/kernel')
-rw-r--r--arch/openrisc/kernel/head.S17
-rw-r--r--arch/openrisc/kernel/setup.c18
2 files changed, 25 insertions, 10 deletions
diff --git a/arch/openrisc/kernel/head.S b/arch/openrisc/kernel/head.S
index c75018d2264..1088b5fca3b 100644
--- a/arch/openrisc/kernel/head.S
+++ b/arch/openrisc/kernel/head.S
@@ -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
diff --git a/arch/openrisc/kernel/setup.c b/arch/openrisc/kernel/setup.c
index 1422f747f52..bf5eba22ce9 100644
--- a/arch/openrisc/kernel/setup.c
+++ b/arch/openrisc/kernel/setup.c
@@ -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)