1 /* 2 * Precise Delay Loops for S390 3 * 4 * Copyright IBM Corp. 1999, 2008 5 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>, 6 * Heiko Carstens <heiko.carstens@de.ibm.com>, 7 */ 8 9 #include <linux/sched.h> 10 #include <linux/delay.h> 11 #include <linux/timex.h> 12 #include <linux/module.h> 13 #include <linux/irqflags.h> 14 #include <linux/interrupt.h> 15 #include <asm/vtimer.h> 16 #include <asm/div64.h> 17 18 void __delay(unsigned long loops) 19 { 20 /* 21 * To end the bloody studid and useless discussion about the 22 * BogoMips number I took the liberty to define the __delay 23 * function in a way that that resulting BogoMips number will 24 * yield the megahertz number of the cpu. The important function 25 * is udelay and that is done using the tod clock. -- martin. 26 */ 27 asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1)); 28 } 29 30 static void __udelay_disabled(unsigned long long usecs) 31 { 32 unsigned long cr0, cr6, new; 33 u64 clock_saved, end; 34 35 end = get_tod_clock() + (usecs << 12); 36 clock_saved = local_tick_disable(); 37 __ctl_store(cr0, 0, 0); 38 __ctl_store(cr6, 6, 6); 39 new = (cr0 & 0xffff00e0) | 0x00000800; 40 __ctl_load(new , 0, 0); 41 new = 0; 42 __ctl_load(new, 6, 6); 43 lockdep_off(); 44 do { 45 set_clock_comparator(end); 46 vtime_stop_cpu(); 47 } while (get_tod_clock_fast() < end); 48 lockdep_on(); 49 __ctl_load(cr0, 0, 0); 50 __ctl_load(cr6, 6, 6); 51 local_tick_enable(clock_saved); 52 } 53 54 static void __udelay_enabled(unsigned long long usecs) 55 { 56 u64 clock_saved, end; 57 58 end = get_tod_clock_fast() + (usecs << 12); 59 do { 60 clock_saved = 0; 61 if (end < S390_lowcore.clock_comparator) { 62 clock_saved = local_tick_disable(); 63 set_clock_comparator(end); 64 } 65 vtime_stop_cpu(); 66 if (clock_saved) 67 local_tick_enable(clock_saved); 68 } while (get_tod_clock_fast() < end); 69 } 70 71 /* 72 * Waits for 'usecs' microseconds using the TOD clock comparator. 73 */ 74 void __udelay(unsigned long long usecs) 75 { 76 unsigned long flags; 77 78 preempt_disable(); 79 local_irq_save(flags); 80 if (in_irq()) { 81 __udelay_disabled(usecs); 82 goto out; 83 } 84 if (in_softirq()) { 85 if (raw_irqs_disabled_flags(flags)) 86 __udelay_disabled(usecs); 87 else 88 __udelay_enabled(usecs); 89 goto out; 90 } 91 if (raw_irqs_disabled_flags(flags)) { 92 local_bh_disable(); 93 __udelay_disabled(usecs); 94 _local_bh_enable(); 95 goto out; 96 } 97 __udelay_enabled(usecs); 98 out: 99 local_irq_restore(flags); 100 preempt_enable(); 101 } 102 EXPORT_SYMBOL(__udelay); 103 104 /* 105 * Simple udelay variant. To be used on startup and reboot 106 * when the interrupt handler isn't working. 107 */ 108 void udelay_simple(unsigned long long usecs) 109 { 110 u64 end; 111 112 end = get_tod_clock_fast() + (usecs << 12); 113 while (get_tod_clock_fast() < end) 114 cpu_relax(); 115 } 116 117 void __ndelay(unsigned long long nsecs) 118 { 119 u64 end; 120 121 nsecs <<= 9; 122 do_div(nsecs, 125); 123 end = get_tod_clock_fast() + nsecs; 124 if (nsecs & ~0xfffUL) 125 __udelay(nsecs >> 12); 126 while (get_tod_clock_fast() < end) 127 barrier(); 128 } 129 EXPORT_SYMBOL(__ndelay); 130