diff options
Diffstat (limited to 'arch/arm/lib/delay.c')
-rw-r--r-- | arch/arm/lib/delay.c | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/arch/arm/lib/delay.c b/arch/arm/lib/delay.c new file mode 100644 index 00000000000..b8d636e8ef8 --- /dev/null +++ b/arch/arm/lib/delay.c @@ -0,0 +1,81 @@ +/* + * Originally from linux/arch/arm/lib/delay.S + * + * Copyright (C) 1995, 1996 Russell King + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#include <linux/module.h> +#include <linux/delay.h> +#include <linux/timex.h> + +/* + * Oh, if only we had a cycle counter... + */ +static void delay_loop(unsigned long loops) +{ + asm volatile( + "1: subs %0, %0, #1 \n" + " bhi 1b \n" + : /* No output */ + : "r" (loops) + ); +} + +#ifdef ARCH_HAS_READ_CURRENT_TIMER +/* + * Assumes read_current_timer() is monotonically increasing + * across calls and wraps at most once within MAX_UDELAY_MS. + */ +void read_current_timer_delay_loop(unsigned long loops) +{ + unsigned long bclock, now; + + read_current_timer(&bclock); + do { + read_current_timer(&now); + } while ((now - bclock) < loops); +} +#endif + +void (*delay_fn)(unsigned long) = delay_loop; + +/* + * loops = usecs * HZ * loops_per_jiffy / 1000000 + */ +void __delay(unsigned long loops) +{ + delay_fn(loops); +} +EXPORT_SYMBOL(__delay); + +/* + * 0 <= xloops <= 0x7fffff06 + * loops_per_jiffy <= 0x01ffffff (max. 3355 bogomips) + */ +void __const_udelay(unsigned long xloops) +{ + unsigned long lpj; + unsigned long loops; + + xloops >>= 14; /* max = 0x01ffffff */ + lpj = loops_per_jiffy >> 10; /* max = 0x0001ffff */ + loops = lpj * xloops; /* max = 0x00007fff */ + loops >>= 6; /* max = 2^32-1 */ + + if (likely(loops)) + __delay(loops); +} +EXPORT_SYMBOL(__const_udelay); + +/* + * usecs <= 2000 + * HZ <= 1000 + */ +void __udelay(unsigned long usecs) +{ + __const_udelay(usecs * ((2199023UL*HZ)>>11)); +} +EXPORT_SYMBOL(__udelay); |