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