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Diffstat (limited to 'include/asm-mips/delay.h')
| -rw-r--r-- | include/asm-mips/delay.h | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/include/asm-mips/delay.h b/include/asm-mips/delay.h new file mode 100644 index 00000000000..d0f68447e5a --- /dev/null +++ b/include/asm-mips/delay.h @@ -0,0 +1,93 @@ +/* + * 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) 1994 by Waldorf Electronics + * Copyright (C) 1995 - 2000, 01, 03 by Ralf Baechle + * Copyright (C) 1999, 2000 Silicon Graphics, Inc. + */ +#ifndef _ASM_DELAY_H +#define _ASM_DELAY_H + +#include <linux/config.h> +#include <linux/param.h> + +#include <asm/compiler.h> + +extern unsigned long loops_per_jiffy; + +static inline void __delay(unsigned long loops) +{ + if (sizeof(long) == 4) + __asm__ __volatile__ ( + ".set\tnoreorder\n" + "1:\tbnez\t%0,1b\n\t" + "subu\t%0,1\n\t" + ".set\treorder" + : "=r" (loops) + : "0" (loops)); + else if (sizeof(long) == 8) + __asm__ __volatile__ ( + ".set\tnoreorder\n" + "1:\tbnez\t%0,1b\n\t" + "dsubu\t%0,1\n\t" + ".set\treorder" + :"=r" (loops) + :"0" (loops)); +} + + +/* + * Division by multiplication: you don't have to worry about + * loss of precision. + * + * Use only for very small delays ( < 1 msec). Should probably use a + * lookup table, really, as the multiplications take much too long with + * short delays. This is a "reasonable" implementation, though (and the + * first constant multiplications gets optimized away if the delay is + * a constant) + */ + +static inline void __udelay(unsigned long usecs, unsigned long lpj) +{ + unsigned long lo; + + /* + * The common rates of 1000 and 128 are rounded wrongly by the + * catchall case for 64-bit. Excessive precission? Probably ... + */ +#if defined(CONFIG_MIPS64) && (HZ == 128) + usecs *= 0x0008637bd05af6c7UL; /* 2**64 / (1000000 / HZ) */ +#elif defined(CONFIG_MIPS64) && (HZ == 1000) + usecs *= 0x004189374BC6A7f0UL; /* 2**64 / (1000000 / HZ) */ +#elif defined(CONFIG_MIPS64) + usecs *= (0x8000000000000000UL / (500000 / HZ)); +#else /* 32-bit junk follows here */ + usecs *= (unsigned long) (((0x8000000000000000ULL / (500000 / HZ)) + + 0x80000000ULL) >> 32); +#endif + + if (sizeof(long) == 4) + __asm__("multu\t%2, %3" + : "=h" (usecs), "=l" (lo) + : "r" (usecs), "r" (lpj) + : GCC_REG_ACCUM); + else if (sizeof(long) == 8) + __asm__("dmultu\t%2, %3" + : "=h" (usecs), "=l" (lo) + : "r" (usecs), "r" (lpj) + : GCC_REG_ACCUM); + + __delay(usecs); +} + +#ifdef CONFIG_SMP +#define __udelay_val cpu_data[smp_processor_id()].udelay_val +#else +#define __udelay_val loops_per_jiffy +#endif + +#define udelay(usecs) __udelay((usecs),__udelay_val) + +#endif /* _ASM_DELAY_H */ |