1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Precise Delay Loops for S390 4 * 5 * Copyright IBM Corp. 1999, 2008 6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>, 7 */ 8 9 #include <linux/processor.h> 10 #include <linux/delay.h> 11 #include <asm/div64.h> 12 #include <asm/timex.h> 13 14 void __delay(unsigned long loops) 15 { 16 /* 17 * Loop 'loops' times. Callers must not assume a specific 18 * amount of time passes before this function returns. 19 */ 20 asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1)); 21 } 22 EXPORT_SYMBOL(__delay); 23 24 static void delay_loop(unsigned long delta) 25 { 26 unsigned long end; 27 28 end = get_tod_clock_monotonic() + delta; 29 while (!tod_after(get_tod_clock_monotonic(), end)) 30 cpu_relax(); 31 } 32 33 void __udelay(unsigned long usecs) 34 { 35 delay_loop(usecs << 12); 36 } 37 EXPORT_SYMBOL(__udelay); 38 39 void __ndelay(unsigned long nsecs) 40 { 41 nsecs <<= 9; 42 do_div(nsecs, 125); 43 delay_loop(nsecs); 44 } 45 EXPORT_SYMBOL(__ndelay); 46