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 (*mips_timer_state)(void); 54 55 int null_perf_irq(void) 56 { 57 return 0; 58 } 59 60 EXPORT_SYMBOL(null_perf_irq); 61 62 int (*perf_irq)(void) = null_perf_irq; 63 64 EXPORT_SYMBOL(perf_irq); 65 66 /* 67 * time_init() - it does the following things. 68 * 69 * 1) plat_time_init() - 70 * a) (optional) set up RTC routines, 71 * b) (optional) calibrate and set the mips_hpt_frequency 72 * (only needed if you intended to use cpu counter as timer interrupt 73 * source) 74 * 2) calculate a couple of cached variables for later usage 75 */ 76 77 unsigned int mips_hpt_frequency; 78 79 void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock) 80 { 81 u64 temp; 82 u32 shift; 83 84 /* Find a shift value */ 85 for (shift = 32; shift > 0; shift--) { 86 temp = (u64) NSEC_PER_SEC << shift; 87 do_div(temp, clock); 88 if ((temp >> 32) == 0) 89 break; 90 } 91 cs->shift = shift; 92 cs->mult = (u32) temp; 93 } 94 95 void __cpuinit clockevent_set_clock(struct clock_event_device *cd, 96 unsigned int clock) 97 { 98 u64 temp; 99 u32 shift; 100 101 /* Find a shift value */ 102 for (shift = 32; shift > 0; shift--) { 103 temp = (u64) clock << shift; 104 do_div(temp, NSEC_PER_SEC); 105 if ((temp >> 32) == 0) 106 break; 107 } 108 cd->shift = shift; 109 cd->mult = (u32) temp; 110 } 111 112 /* 113 * This function exists in order to cause an error due to a duplicate 114 * definition if platform code should have its own implementation. The hook 115 * to use instead is plat_time_init. plat_time_init does not receive the 116 * irqaction pointer argument anymore. This is because any function which 117 * initializes an interrupt timer now takes care of its own request_irq rsp. 118 * setup_irq calls and each clock_event_device should use its own 119 * struct irqrequest. 120 */ 121 void __init plat_timer_setup(void) 122 { 123 BUG(); 124 } 125 126 static __init int cpu_has_mfc0_count_bug(void) 127 { 128 switch (current_cpu_type()) { 129 case CPU_R4000PC: 130 case CPU_R4000SC: 131 case CPU_R4000MC: 132 /* 133 * V3.0 is documented as suffering from the mfc0 from count bug. 134 * Afaik this is the last version of the R4000. Later versions 135 * were marketed as R4400. 136 */ 137 return 1; 138 139 case CPU_R4400PC: 140 case CPU_R4400SC: 141 case CPU_R4400MC: 142 /* 143 * The published errata for the R4400 upto 3.0 say the CPU 144 * has the mfc0 from count bug. 145 */ 146 if ((current_cpu_data.processor_id & 0xff) <= 0x30) 147 return 1; 148 149 /* 150 * we assume newer revisions are ok 151 */ 152 return 0; 153 } 154 155 return 0; 156 } 157 158 void __init time_init(void) 159 { 160 plat_time_init(); 161 162 if (mips_clockevent_init() || !cpu_has_mfc0_count_bug()) 163 init_mips_clocksource(); 164 } 165