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Diffstat (limited to 'arch/m68knommu/include/asm/delay.h')
-rw-r--r-- | arch/m68knommu/include/asm/delay.h | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/arch/m68knommu/include/asm/delay.h b/arch/m68knommu/include/asm/delay.h new file mode 100644 index 0000000..55cbd62 --- /dev/null +++ b/arch/m68knommu/include/asm/delay.h @@ -0,0 +1,76 @@ +#ifndef _M68KNOMMU_DELAY_H +#define _M68KNOMMU_DELAY_H + +/* + * Copyright (C) 1994 Hamish Macdonald + * Copyright (C) 2004 Greg Ungerer <gerg@snapgear.com> + */ + +#include <asm/param.h> + +static inline void __delay(unsigned long loops) +{ +#if defined(CONFIG_COLDFIRE) + /* The coldfire runs this loop at significantly different speeds + * depending upon long word alignment or not. We'll pad it to + * long word alignment which is the faster version. + * The 0x4a8e is of course a 'tstl %fp' instruction. This is better + * than using a NOP (0x4e71) instruction because it executes in one + * cycle not three and doesn't allow for an arbitary delay waiting + * for bus cycles to finish. Also fp/a6 isn't likely to cause a + * stall waiting for the register to become valid if such is added + * to the coldfire at some stage. + */ + __asm__ __volatile__ ( ".balignw 4, 0x4a8e\n\t" + "1: subql #1, %0\n\t" + "jcc 1b" + : "=d" (loops) : "0" (loops)); +#else + __asm__ __volatile__ ( "1: subql #1, %0\n\t" + "jcc 1b" + : "=d" (loops) : "0" (loops)); +#endif +} + +/* + * Ideally we use a 32*32->64 multiply to calculate the number of + * loop iterations, but the older standard 68k and ColdFire do not + * have this instruction. So for them we have a clsoe approximation + * loop using 32*32->32 multiplies only. This calculation based on + * the ARM version of delay. + * + * We want to implement: + * + * loops = (usecs * 0x10c6 * HZ * loops_per_jiffy) / 2^32 + */ + +#define HZSCALE (268435456 / (1000000/HZ)) + +extern unsigned long loops_per_jiffy; + +static inline void _udelay(unsigned long usecs) +{ +#if defined(CONFIG_M68328) || defined(CONFIG_M68EZ328) || \ + defined(CONFIG_M68VZ328) || defined(CONFIG_M68360) || \ + defined(CONFIG_COLDFIRE) + __delay((((usecs * HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6); +#else + unsigned long tmp; + + usecs *= 4295; /* 2**32 / 1000000 */ + __asm__ ("mulul %2,%0:%1" + : "=d" (usecs), "=d" (tmp) + : "d" (usecs), "1" (loops_per_jiffy*HZ)); + __delay(usecs); +#endif +} + +/* + * Moved the udelay() function into library code, no longer inlined. + * I had to change the algorithm because we are overflowing now on + * the faster ColdFire parts. The code is a little bigger, so it makes + * sense to library it. + */ +extern void udelay(unsigned long usecs); + +#endif /* defined(_M68KNOMMU_DELAY_H) */ |