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