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Pointer arguments for 32bit ARC PROMs must reside in CKSEG0/1. While the initial stack resides in CKSEG0 the first kernel thread stack is already placed at a XKPHYS address, which ARC32 can't handle. The workaround here is to use static variables, which are placed into BSS and linked to a CKSEG0 address. Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org
62 lines
1.6 KiB
C
62 lines
1.6 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 1996 David S. Miller (dm@sgi.com)
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* Compatibility with board caches, Ulf Carlsson
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*/
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#include <linux/kernel.h>
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#include <asm/sgialib.h>
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#include <asm/bcache.h>
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#include <asm/setup.h>
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#if defined(CONFIG_64BIT) && defined(CONFIG_FW_ARC32)
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/*
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* For 64bit kernels working with a 32bit ARC PROM pointer arguments
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* for ARC calls need to reside in CKEG0/1. But as soon as the kernel
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* switches to it's first kernel thread stack is set to an address in
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* XKPHYS, so anything on stack can't be used anymore. This is solved
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* by using a * static declartion variables are put into BSS, which is
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* linked to a CKSEG0 address. Since this is only used on UP platforms
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* there is not spinlock needed
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*/
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#define O32_STATIC static
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#else
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#define O32_STATIC
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#endif
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/*
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* IP22 boardcache is not compatible with board caches. Thus we disable it
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* during romvec action. Since r4xx0.c is always compiled and linked with your
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* kernel, this shouldn't cause any harm regardless what MIPS processor you
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* have.
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*
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* The ARC write and read functions seem to interfere with the serial lines
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* in some way. You should be careful with them.
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*/
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void prom_putchar(char c)
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{
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O32_STATIC ULONG cnt;
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O32_STATIC CHAR it;
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it = c;
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bc_disable();
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ArcWrite(1, &it, 1, &cnt);
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bc_enable();
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}
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char prom_getchar(void)
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{
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O32_STATIC ULONG cnt;
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O32_STATIC CHAR c;
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bc_disable();
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ArcRead(0, &c, 1, &cnt);
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bc_enable();
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return c;
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}
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