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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /arch/m68k/include/asm/delay.h | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | arch/m68k/include/asm/delay.h | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/arch/m68k/include/asm/delay.h b/arch/m68k/include/asm/delay.h new file mode 100644 index 000000000..751712f8b --- /dev/null +++ b/arch/m68k/include/asm/delay.h @@ -0,0 +1,125 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _M68K_DELAY_H +#define _M68K_DELAY_H + +#include <asm/param.h> + +/* + * Copyright (C) 1994 Hamish Macdonald + * Copyright (C) 2004 Greg Ungerer <gerg@uclinux.com> + * + * Delay routines, using a pre-computed "loops_per_jiffy" value. + */ + +#if defined(CONFIG_COLDFIRE) +/* + * The ColdFire runs the delay 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 arbitrary 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. + */ +#define DELAY_ALIGN ".balignw 4, 0x4a8e\n\t" +#else +/* + * No instruction alignment required for other m68k types. + */ +#define DELAY_ALIGN +#endif + +static inline void __delay(unsigned long loops) +{ + __asm__ __volatile__ ( + DELAY_ALIGN + "1: subql #1,%0\n\t" + "jcc 1b" + : "=d" (loops) + : "0" (loops)); +} + +extern void __bad_udelay(void); + + +#ifdef CONFIG_CPU_HAS_NO_MULDIV64 +/* + * The simpler m68k and ColdFire processors do not have a 32*32->64 + * multiply instruction. So we need to handle them a little differently. + * We use a bit of shifting and a single 32*32->32 multiply to get close. + */ +#define HZSCALE (268435456 / (1000000 / HZ)) + +#define __const_udelay(u) \ + __delay(((((u) * HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6) + +#else + +static inline void __xdelay(unsigned long xloops) +{ + unsigned long tmp; + + __asm__ ("mulul %2,%0:%1" + : "=d" (xloops), "=d" (tmp) + : "d" (xloops), "1" (loops_per_jiffy)); + __delay(xloops * HZ); +} + +/* + * The definition of __const_udelay is specifically made a macro so that + * the const factor (4295 = 2**32 / 1000000) can be optimized out when + * the delay is a const. + */ +#define __const_udelay(n) (__xdelay((n) * 4295)) + +#endif + +static inline void __udelay(unsigned long usecs) +{ + __const_udelay(usecs); +} + +/* + * 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) + */ +#define udelay(n) (__builtin_constant_p(n) ? \ + ((n) > 20000 ? __bad_udelay() : __const_udelay(n)) : __udelay(n)) + +/* + * nanosecond delay: + * + * ((((HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6) is the number of loops + * per microsecond + * + * 1000 / ((((HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6) is the number of + * nanoseconds per loop + * + * So n / ( 1000 / ((((HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6) ) would + * be the number of loops for n nanoseconds + */ + +/* + * The simpler m68k and ColdFire processors do not have a 32*32->64 + * multiply instruction. So we need to handle them a little differently. + * We use a bit of shifting and a single 32*32->32 multiply to get close. + * This is a macro so that the const version can factor out the first + * multiply and shift. + */ +#define HZSCALE (268435456 / (1000000 / HZ)) + +static inline void ndelay(unsigned long nsec) +{ + __delay(DIV_ROUND_UP(nsec * + ((((HZSCALE) >> 11) * + (loops_per_jiffy >> 11)) >> 6), + 1000)); +} +#define ndelay(n) ndelay(n) + +#endif /* defined(_M68K_DELAY_H) */ |