1 /* 2 * arch/xtensa/kernel/time.c 3 * 4 * Timer and clock support. 5 * 6 * This file is subject to the terms and conditions of the GNU General Public 7 * License. See the file "COPYING" in the main directory of this archive 8 * for more details. 9 * 10 * Copyright (C) 2005 Tensilica Inc. 11 * 12 * Chris Zankel <chris@zankel.net> 13 */ 14 15 #include <linux/errno.h> 16 #include <linux/time.h> 17 #include <linux/timex.h> 18 #include <linux/interrupt.h> 19 #include <linux/module.h> 20 #include <linux/init.h> 21 #include <linux/irq.h> 22 #include <linux/profile.h> 23 #include <linux/delay.h> 24 25 #include <asm/timex.h> 26 #include <asm/platform.h> 27 28 29 DEFINE_SPINLOCK(rtc_lock); 30 EXPORT_SYMBOL(rtc_lock); 31 32 33 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 34 unsigned long ccount_per_jiffy; /* per 1/HZ */ 35 unsigned long ccount_nsec; /* nsec per ccount increment */ 36 #endif 37 38 unsigned int last_ccount_stamp; 39 static long last_rtc_update = 0; 40 41 /* 42 * Scheduler clock - returns current tim in nanosec units. 43 */ 44 45 unsigned long long sched_clock(void) 46 { 47 return (unsigned long long)jiffies * (1000000000 / HZ); 48 } 49 50 static irqreturn_t timer_interrupt(int irq, void *dev_id); 51 static struct irqaction timer_irqaction = { 52 .handler = timer_interrupt, 53 .flags = IRQF_DISABLED, 54 .name = "timer", 55 }; 56 57 void __init time_init(void) 58 { 59 time_t sec_o, sec_n = 0; 60 61 /* The platform must provide a function to calibrate the processor 62 * speed for the CALIBRATE. 63 */ 64 65 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 66 printk("Calibrating CPU frequency "); 67 platform_calibrate_ccount(); 68 printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ), 69 (int)(ccount_per_jiffy/(10000/HZ))%100); 70 #endif 71 72 /* Set time from RTC (if provided) */ 73 74 if (platform_get_rtc_time(&sec_o) == 0) 75 while (platform_get_rtc_time(&sec_n)) 76 if (sec_o != sec_n) 77 break; 78 79 xtime.tv_nsec = 0; 80 last_rtc_update = xtime.tv_sec = sec_n; 81 last_ccount_stamp = get_ccount(); 82 83 set_normalized_timespec(&wall_to_monotonic, 84 -xtime.tv_sec, -xtime.tv_nsec); 85 86 /* Initialize the linux timer interrupt. */ 87 88 setup_irq(LINUX_TIMER_INT, &timer_irqaction); 89 set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY); 90 } 91 92 93 int do_settimeofday(struct timespec *tv) 94 { 95 time_t wtm_sec, sec = tv->tv_sec; 96 long wtm_nsec, nsec = tv->tv_nsec; 97 unsigned long ccount; 98 99 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) 100 return -EINVAL; 101 102 write_seqlock_irq(&xtime_lock); 103 104 /* This is revolting. We need to set "xtime" correctly. However, the 105 * value in this location is the value at the most recent update of 106 * wall time. Discover what correction gettimeofday() would have 107 * made, and then undo it! 108 */ 109 ccount = get_ccount(); 110 nsec -= (ccount - last_ccount_stamp) * CCOUNT_NSEC; 111 112 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec); 113 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec); 114 115 set_normalized_timespec(&xtime, sec, nsec); 116 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec); 117 118 ntp_clear(); 119 write_sequnlock_irq(&xtime_lock); 120 return 0; 121 } 122 123 EXPORT_SYMBOL(do_settimeofday); 124 125 126 void do_gettimeofday(struct timeval *tv) 127 { 128 unsigned long flags; 129 unsigned long sec, usec, delta, seq; 130 131 do { 132 seq = read_seqbegin_irqsave(&xtime_lock, flags); 133 134 delta = get_ccount() - last_ccount_stamp; 135 sec = xtime.tv_sec; 136 usec = (xtime.tv_nsec / NSEC_PER_USEC); 137 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); 138 139 usec += (delta * CCOUNT_NSEC) / NSEC_PER_USEC; 140 for (; usec >= 1000000; sec++, usec -= 1000000) 141 ; 142 143 tv->tv_sec = sec; 144 tv->tv_usec = usec; 145 } 146 147 EXPORT_SYMBOL(do_gettimeofday); 148 149 /* 150 * The timer interrupt is called HZ times per second. 151 */ 152 153 irqreturn_t timer_interrupt (int irq, void *dev_id) 154 { 155 156 unsigned long next; 157 158 next = get_linux_timer(); 159 160 again: 161 while ((signed long)(get_ccount() - next) > 0) { 162 163 profile_tick(CPU_PROFILING); 164 #ifndef CONFIG_SMP 165 update_process_times(user_mode(get_irq_regs())); 166 #endif 167 168 write_seqlock(&xtime_lock); 169 170 last_ccount_stamp = next; 171 next += CCOUNT_PER_JIFFY; 172 do_timer (1); /* Linux handler in kernel/timer.c */ 173 174 if (ntp_synced() && 175 xtime.tv_sec - last_rtc_update >= 659 && 176 abs((xtime.tv_nsec/1000)-(1000000-1000000/HZ))<5000000/HZ) { 177 178 if (platform_set_rtc_time(xtime.tv_sec+1) == 0) 179 last_rtc_update = xtime.tv_sec+1; 180 else 181 /* Do it again in 60 s */ 182 last_rtc_update += 60; 183 } 184 write_sequnlock(&xtime_lock); 185 } 186 187 /* NOTE: writing CCOMPAREn clears the interrupt. */ 188 189 set_linux_timer (next); 190 191 /* Make sure we didn't miss any tick... */ 192 193 if ((signed long)(get_ccount() - next) > 0) 194 goto again; 195 196 /* Allow platform to do something useful (Wdog). */ 197 198 platform_heartbeat(); 199 200 return IRQ_HANDLED; 201 } 202 203 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY 204 void __devinit calibrate_delay(void) 205 { 206 loops_per_jiffy = CCOUNT_PER_JIFFY; 207 printk("Calibrating delay loop (skipped)... " 208 "%lu.%02lu BogoMIPS preset\n", 209 loops_per_jiffy/(1000000/HZ), 210 (loops_per_jiffy/(10000/HZ)) % 100); 211 } 212 #endif 213 214