diff options
Diffstat (limited to 'arch/mips/lib/uncached.c')
| -rw-r--r-- | arch/mips/lib/uncached.c | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/arch/mips/lib/uncached.c b/arch/mips/lib/uncached.c new file mode 100644 index 00000000000..98ce89f8068 --- /dev/null +++ b/arch/mips/lib/uncached.c @@ -0,0 +1,76 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 2005 Thiemo Seufer + * Copyright (C) 2005 MIPS Technologies, Inc. All rights reserved. + * Author: Maciej W. Rozycki <macro@mips.com> + */ + +#include <linux/init.h> + +#include <asm/addrspace.h> +#include <asm/bug.h> + +#ifndef CKSEG2 +#define CKSEG2 CKSSEG +#endif +#ifndef TO_PHYS_MASK +#define TO_PHYS_MASK -1 +#endif + +/* + * FUNC is executed in one of the uncached segments, depending on its + * original address as follows: + * + * 1. If the original address is in CKSEG0 or CKSEG1, then the uncached + * segment used is CKSEG1. + * 2. If the original address is in XKPHYS, then the uncached segment + * used is XKPHYS(2). + * 3. Otherwise it's a bug. + * + * The same remapping is done with the stack pointer. Stack handling + * works because we don't handle stack arguments or more complex return + * values, so we can avoid sharing the same stack area between a cached + * and the uncached mode. + */ +unsigned long __init run_uncached(void *func) +{ + register long sp __asm__("$sp"); + register long ret __asm__("$2"); + long lfunc = (long)func, ufunc; + long usp; + + if (sp >= (long)CKSEG0 && sp < (long)CKSEG2) + usp = CKSEG1ADDR(sp); + else if ((long long)sp >= (long long)PHYS_TO_XKPHYS(0LL, 0) && + (long long)sp < (long long)PHYS_TO_XKPHYS(8LL, 0)) + usp = PHYS_TO_XKPHYS((long long)K_CALG_UNCACHED, + XKPHYS_TO_PHYS((long long)sp)); + else { + BUG(); + usp = sp; + } + if (lfunc >= (long)CKSEG0 && lfunc < (long)CKSEG2) + ufunc = CKSEG1ADDR(lfunc); + else if ((long long)lfunc >= (long long)PHYS_TO_XKPHYS(0LL, 0) && + (long long)lfunc < (long long)PHYS_TO_XKPHYS(8LL, 0)) + ufunc = PHYS_TO_XKPHYS((long long)K_CALG_UNCACHED, + XKPHYS_TO_PHYS((long long)lfunc)); + else { + BUG(); + ufunc = lfunc; + } + + __asm__ __volatile__ ( + " move $16, $sp\n" + " move $sp, %1\n" + " jalr %2\n" + " move $sp, $16" + : "=r" (ret) + : "r" (usp), "r" (ufunc) + : "$16", "$31"); + + return ret; +} |