1 /* 2 * Copyright 2001 MontaVista Software Inc. 3 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net 4 * Copyright (c) 2003, 2004 Maciej W. Rozycki 5 * 6 * Common time service routines for MIPS machines. 7 * 8 * This program is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License as published by the 10 * Free Software Foundation; either version 2 of the License, or (at your 11 * option) any later version. 12 */ 13 #include <linux/bug.h> 14 #include <linux/clockchips.h> 15 #include <linux/types.h> 16 #include <linux/kernel.h> 17 #include <linux/init.h> 18 #include <linux/sched.h> 19 #include <linux/param.h> 20 #include <linux/time.h> 21 #include <linux/timex.h> 22 #include <linux/smp.h> 23 #include <linux/spinlock.h> 24 #include <linux/module.h> 25 26 #include <asm/cpu-features.h> 27 #include <asm/div64.h> 28 #include <asm/smtc_ipi.h> 29 #include <asm/time.h> 30 31 /* 32 * forward reference 33 */ 34 DEFINE_SPINLOCK(rtc_lock); 35 EXPORT_SYMBOL(rtc_lock); 36 37 int __weak rtc_mips_set_time(unsigned long sec) 38 { 39 return 0; 40 } 41 EXPORT_SYMBOL(rtc_mips_set_time); 42 43 int __weak rtc_mips_set_mmss(unsigned long nowtime) 44 { 45 return rtc_mips_set_time(nowtime); 46 } 47 48 int update_persistent_clock(struct timespec now) 49 { 50 return rtc_mips_set_mmss(now.tv_sec); 51 } 52 53 int null_perf_irq(void) 54 { 55 return 0; 56 } 57 58 EXPORT_SYMBOL(null_perf_irq); 59 60 int (*perf_irq)(void) = null_perf_irq; 61 62 EXPORT_SYMBOL(perf_irq); 63 64 /* 65 * time_init() - it does the following things. 66 * 67 * 1) plat_time_init() - 68 * a) (optional) set up RTC routines, 69 * b) (optional) calibrate and set the mips_hpt_frequency 70 * (only needed if you intended to use cpu counter as timer interrupt 71 * source) 72 * 2) calculate a couple of cached variables for later usage 73 */ 74 75 unsigned int mips_hpt_frequency; 76 77 void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock) 78 { 79 u64 temp; 80 u32 shift; 81 82 /* Find a shift value */ 83 for (shift = 32; shift > 0; shift--) { 84 temp = (u64) NSEC_PER_SEC << shift; 85 do_div(temp, clock); 86 if ((temp >> 32) == 0) 87 break; 88 } 89 cs->shift = shift; 90 cs->mult = (u32) temp; 91 } 92 93 void __cpuinit clockevent_set_clock(struct clock_event_device *cd, 94 unsigned int clock) 95 { 96 u64 temp; 97 u32 shift; 98 99 /* Find a shift value */ 100 for (shift = 32; shift > 0; shift--) { 101 temp = (u64) clock << shift; 102 do_div(temp, NSEC_PER_SEC); 103 if ((temp >> 32) == 0) 104 break; 105 } 106 cd->shift = shift; 107 cd->mult = (u32) temp; 108 } 109 110 /* 111 * This function exists in order to cause an error due to a duplicate 112 * definition if platform code should have its own implementation. The hook 113 * to use instead is plat_time_init. plat_time_init does not receive the 114 * irqaction pointer argument anymore. This is because any function which 115 * initializes an interrupt timer now takes care of its own request_irq rsp. 116 * setup_irq calls and each clock_event_device should use its own 117 * struct irqrequest. 118 */ 119 void __init plat_timer_setup(void) 120 { 121 BUG(); 122 } 123 124 static __init int cpu_has_mfc0_count_bug(void) 125 { 126 switch (current_cpu_type()) { 127 case CPU_R4000PC: 128 case CPU_R4000SC: 129 case CPU_R4000MC: 130 /* 131 * V3.0 is documented as suffering from the mfc0 from count bug. 132 * Afaik this is the last version of the R4000. Later versions 133 * were marketed as R4400. 134 */ 135 return 1; 136 137 case CPU_R4400PC: 138 case CPU_R4400SC: 139 case CPU_R4400MC: 140 /* 141 * The published errata for the R4400 upto 3.0 say the CPU 142 * has the mfc0 from count bug. 143 */ 144 if ((current_cpu_data.processor_id & 0xff) <= 0x30) 145 return 1; 146 147 /* 148 * we assume newer revisions are ok 149 */ 150 return 0; 151 } 152 153 return 0; 154 } 155 156 void __init time_init(void) 157 { 158 plat_time_init(); 159 160 if (mips_clockevent_init() || !cpu_has_mfc0_count_bug()) 161 init_mips_clocksource(); 162 } 163