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 42 int __weak rtc_mips_set_mmss(unsigned long nowtime) 43 { 44 return rtc_mips_set_time(nowtime); 45 } 46 47 int update_persistent_clock(struct timespec now) 48 { 49 return rtc_mips_set_mmss(now.tv_sec); 50 } 51 52 static int null_perf_irq(void) 53 { 54 return 0; 55 } 56 57 int (*perf_irq)(void) = null_perf_irq; 58 59 EXPORT_SYMBOL(perf_irq); 60 61 /* 62 * time_init() - it does the following things. 63 * 64 * 1) plat_time_init() - 65 * a) (optional) set up RTC routines, 66 * b) (optional) calibrate and set the mips_hpt_frequency 67 * (only needed if you intended to use cpu counter as timer interrupt 68 * source) 69 * 2) calculate a couple of cached variables for later usage 70 */ 71 72 unsigned int mips_hpt_frequency; 73 74 void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock) 75 { 76 u64 temp; 77 u32 shift; 78 79 /* Find a shift value */ 80 for (shift = 32; shift > 0; shift--) { 81 temp = (u64) NSEC_PER_SEC << shift; 82 do_div(temp, clock); 83 if ((temp >> 32) == 0) 84 break; 85 } 86 cs->shift = shift; 87 cs->mult = (u32) temp; 88 } 89 90 void __cpuinit clockevent_set_clock(struct clock_event_device *cd, 91 unsigned int clock) 92 { 93 u64 temp; 94 u32 shift; 95 96 /* Find a shift value */ 97 for (shift = 32; shift > 0; shift--) { 98 temp = (u64) clock << shift; 99 do_div(temp, NSEC_PER_SEC); 100 if ((temp >> 32) == 0) 101 break; 102 } 103 cd->shift = shift; 104 cd->mult = (u32) temp; 105 } 106 107 /* 108 * This function exists in order to cause an error due to a duplicate 109 * definition if platform code should have its own implementation. The hook 110 * to use instead is plat_time_init. plat_time_init does not receive the 111 * irqaction pointer argument anymore. This is because any function which 112 * initializes an interrupt timer now takes care of its own request_irq rsp. 113 * setup_irq calls and each clock_event_device should use its own 114 * struct irqrequest. 115 */ 116 void __init plat_timer_setup(void) 117 { 118 BUG(); 119 } 120 121 static __init int cpu_has_mfc0_count_bug(void) 122 { 123 switch (current_cpu_type()) { 124 case CPU_R4000PC: 125 case CPU_R4000SC: 126 case CPU_R4000MC: 127 /* 128 * V3.0 is documented as suffering from the mfc0 from count bug. 129 * Afaik this is the last version of the R4000. Later versions 130 * were marketed as R4400. 131 */ 132 return 1; 133 134 case CPU_R4400PC: 135 case CPU_R4400SC: 136 case CPU_R4400MC: 137 /* 138 * The published errata for the R4400 upto 3.0 say the CPU 139 * has the mfc0 from count bug. 140 */ 141 if ((current_cpu_data.processor_id & 0xff) <= 0x30) 142 return 1; 143 144 /* 145 * we assume newer revisions are ok 146 */ 147 return 0; 148 } 149 150 return 0; 151 } 152 153 void __init time_init(void) 154 { 155 plat_time_init(); 156 157 if (!mips_clockevent_init() || !cpu_has_mfc0_count_bug()) 158 init_mips_clocksource(); 159 } 160