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/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 /* 75 * This function exists in order to cause an error due to a duplicate 76 * definition if platform code should have its own implementation. The hook 77 * to use instead is plat_time_init. plat_time_init does not receive the 78 * irqaction pointer argument anymore. This is because any function which 79 * initializes an interrupt timer now takes care of its own request_irq rsp. 80 * setup_irq calls and each clock_event_device should use its own 81 * struct irqrequest. 82 */ 83 void __init plat_timer_setup(void) 84 { 85 BUG(); 86 } 87 88 static __init int cpu_has_mfc0_count_bug(void) 89 { 90 switch (current_cpu_type()) { 91 case CPU_R4000PC: 92 case CPU_R4000SC: 93 case CPU_R4000MC: 94 /* 95 * V3.0 is documented as suffering from the mfc0 from count bug. 96 * Afaik this is the last version of the R4000. Later versions 97 * were marketed as R4400. 98 */ 99 return 1; 100 101 case CPU_R4400PC: 102 case CPU_R4400SC: 103 case CPU_R4400MC: 104 /* 105 * The published errata for the R4400 up to 3.0 say the CPU 106 * has the mfc0 from count bug. 107 */ 108 if ((current_cpu_data.processor_id & 0xff) <= 0x30) 109 return 1; 110 111 /* 112 * we assume newer revisions are ok 113 */ 114 return 0; 115 } 116 117 return 0; 118 } 119 120 void __init time_init(void) 121 { 122 plat_time_init(); 123 124 /* 125 * The use of the R4k timer as a clock event takes precedence; 126 * if reading the Count register might interfere with the timer 127 * interrupt, then we don't use the timer as a clock source. 128 * We may still use the timer as a clock source though if the 129 * timer interrupt isn't reliable; the interference doesn't 130 * matter then, because we don't use the interrupt. 131 */ 132 if (mips_clockevent_init() != 0 || !cpu_has_mfc0_count_bug()) 133 init_mips_clocksource(); 134 } 135