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/export.h> 25 26 #include <asm/cpu-features.h> 27 #include <asm/cpu-type.h> 28 #include <asm/div64.h> 29 #include <asm/smtc_ipi.h> 30 #include <asm/time.h> 31 32 /* 33 * forward reference 34 */ 35 DEFINE_SPINLOCK(rtc_lock); 36 EXPORT_SYMBOL(rtc_lock); 37 38 int __weak rtc_mips_set_time(unsigned long sec) 39 { 40 return 0; 41 } 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 static int null_perf_irq(void) 54 { 55 return 0; 56 } 57 58 int (*perf_irq)(void) = null_perf_irq; 59 60 EXPORT_SYMBOL(perf_irq); 61 62 /* 63 * time_init() - it does the following things. 64 * 65 * 1) plat_time_init() - 66 * a) (optional) set up RTC routines, 67 * b) (optional) calibrate and set the mips_hpt_frequency 68 * (only needed if you intended to use cpu counter as timer interrupt 69 * source) 70 * 2) calculate a couple of cached variables for later usage 71 */ 72 73 unsigned int mips_hpt_frequency; 74 75 /* 76 * This function exists in order to cause an error due to a duplicate 77 * definition if platform code should have its own implementation. The hook 78 * to use instead is plat_time_init. plat_time_init does not receive the 79 * irqaction pointer argument anymore. This is because any function which 80 * initializes an interrupt timer now takes care of its own request_irq rsp. 81 * setup_irq calls and each clock_event_device should use its own 82 * struct irqrequest. 83 */ 84 void __init plat_timer_setup(void) 85 { 86 BUG(); 87 } 88 89 static __init int cpu_has_mfc0_count_bug(void) 90 { 91 switch (current_cpu_type()) { 92 case CPU_R4000PC: 93 case CPU_R4000SC: 94 case CPU_R4000MC: 95 /* 96 * V3.0 is documented as suffering from the mfc0 from count bug. 97 * Afaik this is the last version of the R4000. Later versions 98 * were marketed as R4400. 99 */ 100 return 1; 101 102 case CPU_R4400PC: 103 case CPU_R4400SC: 104 case CPU_R4400MC: 105 /* 106 * The published errata for the R4400 up to 3.0 say the CPU 107 * has the mfc0 from count bug. 108 */ 109 if ((current_cpu_data.processor_id & 0xff) <= 0x30) 110 return 1; 111 112 /* 113 * we assume newer revisions are ok 114 */ 115 return 0; 116 } 117 118 return 0; 119 } 120 121 void __init time_init(void) 122 { 123 plat_time_init(); 124 125 /* 126 * The use of the R4k timer as a clock event takes precedence; 127 * if reading the Count register might interfere with the timer 128 * interrupt, then we don't use the timer as a clock source. 129 * We may still use the timer as a clock source though if the 130 * timer interrupt isn't reliable; the interference doesn't 131 * matter then, because we don't use the interrupt. 132 */ 133 if (mips_clockevent_init() != 0 || !cpu_has_mfc0_count_bug()) 134 init_mips_clocksource(); 135 } 136