1 #ifndef _M68KNOMMU_DELAY_H
2 #define _M68KNOMMU_DELAY_H
5 * Copyright (C) 1994 Hamish Macdonald
6 * Copyright (C) 2004 Greg Ungerer <gerg@snapgear.com>
11 static inline void __delay(unsigned long loops
)
13 #if defined(CONFIG_COLDFIRE)
14 /* The coldfire runs this loop at significantly different speeds
15 * depending upon long word alignment or not. We'll pad it to
16 * long word alignment which is the faster version.
17 * The 0x4a8e is of course a 'tstl %fp' instruction. This is better
18 * than using a NOP (0x4e71) instruction because it executes in one
19 * cycle not three and doesn't allow for an arbitary delay waiting
20 * for bus cycles to finish. Also fp/a6 isn't likely to cause a
21 * stall waiting for the register to become valid if such is added
22 * to the coldfire at some stage.
24 __asm__
__volatile__ ( ".balignw 4, 0x4a8e\n\t"
27 : "=d" (loops
) : "0" (loops
));
29 __asm__
__volatile__ ( "1: subql #1, %0\n\t"
31 : "=d" (loops
) : "0" (loops
));
36 * Ideally we use a 32*32->64 multiply to calculate the number of
37 * loop iterations, but the older standard 68k and ColdFire do not
38 * have this instruction. So for them we have a clsoe approximation
39 * loop using 32*32->32 multiplies only. This calculation based on
40 * the ARM version of delay.
42 * We want to implement:
44 * loops = (usecs * 0x10c6 * HZ * loops_per_jiffy) / 2^32
47 #define HZSCALE (268435456 / (1000000/HZ))
49 extern unsigned long loops_per_jiffy
;
51 static inline void _udelay(unsigned long usecs
)
53 #if defined(CONFIG_M68328) || defined(CONFIG_M68EZ328) || \
54 defined(CONFIG_M68VZ328) || defined(CONFIG_M68360) || \
55 defined(CONFIG_COLDFIRE)
56 __delay((((usecs
* HZSCALE
) >> 11) * (loops_per_jiffy
>> 11)) >> 6);
60 usecs
*= 4295; /* 2**32 / 1000000 */
61 __asm__ ("mulul %2,%0:%1"
62 : "=d" (usecs
), "=d" (tmp
)
63 : "d" (usecs
), "1" (loops_per_jiffy
*HZ
));
69 * Moved the udelay() function into library code, no longer inlined.
70 * I had to change the algorithm because we are overflowing now on
71 * the faster ColdFire parts. The code is a little bigger, so it makes
72 * sense to library it.
74 extern void udelay(unsigned long usecs
);
76 #endif /* defined(_M68KNOMMU_DELAY_H) */
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