1 /* 2 * Precise Delay Loops for Meta 3 * 4 * Copyright (C) 1993 Linus Torvalds 5 * Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz> 6 * Copyright (C) 2007,2009 Imagination Technologies Ltd. 7 * 8 */ 9 10 #include <linux/export.h> 11 #include <linux/sched.h> 12 #include <linux/delay.h> 13 14 #include <asm/core_reg.h> 15 #include <asm/processor.h> 16 17 /* 18 * TXTACTCYC is only 24 bits, so on chips with fast clocks it will wrap 19 * many times per-second. If it does wrap __delay will return prematurely, 20 * but this is only likely with large delay values. 21 * 22 * We also can't implement read_current_timer() with TXTACTCYC due to 23 * this wrapping behaviour. 24 */ 25 #define rdtimer(t) t = __core_reg_get(TXTACTCYC) 26 __delay(unsigned long loops)27void __delay(unsigned long loops) 28 { 29 unsigned long bclock, now; 30 31 rdtimer(bclock); 32 do { 33 asm("NOP"); 34 rdtimer(now); 35 } while ((now-bclock) < loops); 36 } 37 EXPORT_SYMBOL(__delay); 38 __const_udelay(unsigned long xloops)39inline void __const_udelay(unsigned long xloops) 40 { 41 u64 loops = (u64)xloops * (u64)loops_per_jiffy * HZ; 42 __delay(loops >> 32); 43 } 44 EXPORT_SYMBOL(__const_udelay); 45 __udelay(unsigned long usecs)46void __udelay(unsigned long usecs) 47 { 48 __const_udelay(usecs * 0x000010c7); /* 2**32 / 1000000 (rounded up) */ 49 } 50 EXPORT_SYMBOL(__udelay); 51 __ndelay(unsigned long nsecs)52void __ndelay(unsigned long nsecs) 53 { 54 __const_udelay(nsecs * 0x00005); /* 2**32 / 1000000000 (rounded up) */ 55 } 56 EXPORT_SYMBOL(__ndelay); 57