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/config.h> 16 #include <linux/errno.h> 17 #include <linux/time.h> 18 #include <linux/timex.h> 19 #include <linux/interrupt.h> 20 #include <linux/module.h> 21 #include <linux/init.h> 22 #include <linux/irq.h> 23 #include <linux/profile.h> 24 #include <linux/delay.h> 25 26 #include <asm/timex.h> 27 #include <asm/platform.h> 28 29 30 extern volatile unsigned long wall_jiffies; 31 32 spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED; 33 EXPORT_SYMBOL(rtc_lock); 34 35 36 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 37 unsigned long ccount_per_jiffy; /* per 1/HZ */ 38 unsigned long ccount_nsec; /* nsec per ccount increment */ 39 #endif 40 41 unsigned int last_ccount_stamp; 42 static long last_rtc_update = 0; 43 44 /* 45 * Scheduler clock - returns current tim in nanosec units. 46 */ 47 48 unsigned long long sched_clock(void) 49 { 50 return (unsigned long long)jiffies * (1000000000 / HZ); 51 } 52 53 static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs); 54 static struct irqaction timer_irqaction = { 55 .handler = timer_interrupt, 56 .flags = SA_INTERRUPT, 57 .name = "timer", 58 }; 59 60 void __init time_init(void) 61 { 62 time_t sec_o, sec_n = 0; 63 64 /* The platform must provide a function to calibrate the processor 65 * speed for the CALIBRATE. 66 */ 67 68 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT 69 printk("Calibrating CPU frequency "); 70 platform_calibrate_ccount(); 71 printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ), 72 (int)(ccount_per_jiffy/(10000/HZ))%100); 73 #endif 74 75 /* Set time from RTC (if provided) */ 76 77 if (platform_get_rtc_time(&sec_o) == 0) 78 while (platform_get_rtc_time(&sec_n)) 79 if (sec_o != sec_n) 80 break; 81 82 xtime.tv_nsec = 0; 83 last_rtc_update = xtime.tv_sec = sec_n; 84 last_ccount_stamp = get_ccount(); 85 86 set_normalized_timespec(&wall_to_monotonic, 87 -xtime.tv_sec, -xtime.tv_nsec); 88 89 /* Initialize the linux timer interrupt. */ 90 91 setup_irq(LINUX_TIMER_INT, &timer_irqaction); 92 set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY); 93 } 94 95 96 int do_settimeofday(struct timespec *tv) 97 { 98 time_t wtm_sec, sec = tv->tv_sec; 99 long wtm_nsec, nsec = tv->tv_nsec; 100 unsigned long ccount; 101 102 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) 103 return -EINVAL; 104 105 write_seqlock_irq(&xtime_lock); 106 107 /* This is revolting. We need to set "xtime" correctly. However, the 108 * value in this location is the value at the most recent update of 109 * wall time. Discover what correction gettimeofday() would have 110 * made, and then undo it! 111 */ 112 ccount = get_ccount(); 113 nsec -= (ccount - last_ccount_stamp) * CCOUNT_NSEC; 114 nsec -= (jiffies - wall_jiffies) * CCOUNT_PER_JIFFY * CCOUNT_NSEC; 115 116 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec); 117 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec); 118 119 set_normalized_timespec(&xtime, sec, nsec); 120 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec); 121 122 ntp_clear(); 123 write_sequnlock_irq(&xtime_lock); 124 return 0; 125 } 126 127 EXPORT_SYMBOL(do_settimeofday); 128 129 130 void do_gettimeofday(struct timeval *tv) 131 { 132 unsigned long flags; 133 unsigned long sec, usec, delta, lost, seq; 134 135 do { 136 seq = read_seqbegin_irqsave(&xtime_lock, flags); 137 138 delta = get_ccount() - last_ccount_stamp; 139 sec = xtime.tv_sec; 140 usec = (xtime.tv_nsec / NSEC_PER_USEC); 141 142 lost = jiffies - wall_jiffies; 143 144 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); 145 146 usec += lost * (1000000UL/HZ) + (delta * CCOUNT_NSEC) / NSEC_PER_USEC; 147 for (; usec >= 1000000; sec++, usec -= 1000000) 148 ; 149 150 tv->tv_sec = sec; 151 tv->tv_usec = usec; 152 } 153 154 EXPORT_SYMBOL(do_gettimeofday); 155 156 /* 157 * The timer interrupt is called HZ times per second. 158 */ 159 160 irqreturn_t timer_interrupt (int irq, void *dev_id, struct pt_regs *regs) 161 { 162 163 unsigned long next; 164 165 next = get_linux_timer(); 166 167 again: 168 while ((signed long)(get_ccount() - next) > 0) { 169 170 profile_tick(CPU_PROFILING, regs); 171 #ifndef CONFIG_SMP 172 update_process_times(user_mode(regs)); 173 #endif 174 175 write_seqlock(&xtime_lock); 176 177 last_ccount_stamp = next; 178 next += CCOUNT_PER_JIFFY; 179 do_timer (regs); /* Linux handler in kernel/timer.c */ 180 181 if (ntp_synced() && 182 xtime.tv_sec - last_rtc_update >= 659 && 183 abs((xtime.tv_nsec/1000)-(1000000-1000000/HZ))<5000000/HZ && 184 jiffies - wall_jiffies == 1) { 185 186 if (platform_set_rtc_time(xtime.tv_sec+1) == 0) 187 last_rtc_update = xtime.tv_sec+1; 188 else 189 /* Do it again in 60 s */ 190 last_rtc_update += 60; 191 } 192 write_sequnlock(&xtime_lock); 193 } 194 195 /* NOTE: writing CCOMPAREn clears the interrupt. */ 196 197 set_linux_timer (next); 198 199 /* Make sure we didn't miss any tick... */ 200 201 if ((signed long)(get_ccount() - next) > 0) 202 goto again; 203 204 /* Allow platform to do something useful (Wdog). */ 205 206 platform_heartbeat(); 207 208 return IRQ_HANDLED; 209 } 210 211 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY 212 void __devinit calibrate_delay(void) 213 { 214 loops_per_jiffy = CCOUNT_PER_JIFFY; 215 printk("Calibrating delay loop (skipped)... " 216 "%lu.%02lu BogoMIPS preset\n", 217 loops_per_jiffy/(1000000/HZ), 218 (loops_per_jiffy/(10000/HZ)) % 100); 219 } 220 #endif 221 222