u-boot/arch/nios2/cpu/cpu.c
Thomas Chou 7a6a7d10e6 nios2: fix out of reach case for do_reset
There is a limitation (or bug?) of nios2 toolchain. The nios2 gcc
didn't generate correct code when the reset vector is passed as a
constant. It just generated a direct "call", which was wrong when
the reset vector was not located in the same 256MB span as u-boot.

The "Nios II Processor Reference Handbook" said,
"call can transfer execution anywhere within the 256 MByte range
determined by PC31..28. The Nios II GNU linker does not automatically
handle cases in which the address is out of this range."

So we have to use registered "callr" instruction to do the job.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Signed-off-by: Scott McNutt <smcnutt@psyent.com>
2010-08-19 22:15:49 -04:00

49 lines
1.4 KiB
C

/*
* (C) Copyright 2004, Psyent Corporation <www.psyent.com>
* Scott McNutt <smcnutt@psyent.com>
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <common.h>
#include <nios2.h>
#include <nios2-io.h>
#if defined (CONFIG_SYS_NIOS_SYSID_BASE)
extern void display_sysid (void);
#endif /* CONFIG_SYS_NIOS_SYSID_BASE */
int checkcpu (void)
{
printf ("CPU : Nios-II\n");
#if !defined(CONFIG_SYS_NIOS_SYSID_BASE)
printf ("SYSID : <unknown>\n");
#else
display_sysid ();
#endif
return (0);
}
int do_reset(void)
{
disable_interrupts();
/* indirect call to go beyond 256MB limitation of toolchain */
nios2_callr(CONFIG_SYS_RESET_ADDR);
return 0;
}