2 * File: arch/blackfin/kernel/time.c
3 * Based on: none - original work
7 * Description: This file contains the bfin-specific time handling details.
8 * Most of the stuff is located in the machine specific files.
9 * FIXME: (This file is subject for removal)
12 * Copyright 2004-2008 Analog Devices Inc.
14 * Bugs: Enter bugs at http://blackfin.uclinux.org/
16 * This program is free software; you can redistribute it and/or modify
17 * it under the terms of the GNU General Public License as published by
18 * the Free Software Foundation; either version 2 of the License, or
19 * (at your option) any later version.
21 * This program is distributed in the hope that it will be useful,
22 * but WITHOUT ANY WARRANTY; without even the implied warranty of
23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
24 * GNU General Public License for more details.
26 * You should have received a copy of the GNU General Public License
27 * along with this program; if not, see the file COPYING, or write
28 * to the Free Software Foundation, Inc.,
29 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
32 #include <linux/module.h>
33 #include <linux/profile.h>
34 #include <linux/interrupt.h>
35 #include <linux/time.h>
36 #include <linux/irq.h>
37 #include <linux/delay.h>
39 #include <asm/blackfin.h>
41 #include <asm/gptimers.h>
43 /* This is an NTP setting */
44 #define TICK_SIZE (tick_nsec / 1000)
46 static void time_sched_init(irq_handler_t timer_routine);
47 static unsigned long gettimeoffset(void);
49 static struct irqaction bfin_timer_irq = {
50 .name = "BFIN Timer Tick",
51 #ifdef CONFIG_IRQ_PER_CPU
52 .flags = IRQF_DISABLED | IRQF_PERCPU,
54 .flags = IRQF_DISABLED
58 void setup_core_timer(void)
62 /* power up the timer, but don't enable it just yet */
67 * the TSCALE prescaler counter.
69 bfin_write_TSCALE((TIME_SCALE - 1));
71 tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
72 bfin_write_TPERIOD(tcount);
73 bfin_write_TCOUNT(tcount);
75 /* now enable the timer */
81 #ifdef CONFIG_TICK_SOURCE_SYSTMR0
82 void setup_system_timer0(void)
84 /* Power down the core timer, just to play safe. */
87 disable_gptimers(TIMER0bit);
88 set_gptimer_status(0, TIMER_STATUS_TRUN0);
89 while (get_gptimer_status(0) & TIMER_STATUS_TRUN0)
92 set_gptimer_config(0, 0x59); /* IRQ enable, periodic, PWM_OUT, SCLKed, OUT PAD disabled */
93 set_gptimer_period(TIMER0_id, get_sclk() / HZ);
94 set_gptimer_pwidth(TIMER0_id, 1);
96 enable_gptimers(TIMER0bit);
101 time_sched_init(irqreturn_t(*timer_routine) (int, void *))
103 #ifdef CONFIG_TICK_SOURCE_SYSTMR0
104 setup_system_timer0();
108 bfin_timer_irq.handler = (irq_handler_t)timer_routine;
109 #ifdef CONFIG_TICK_SOURCE_SYSTMR0
110 setup_irq(IRQ_TIMER0, &bfin_timer_irq);
112 setup_irq(IRQ_CORETMR, &bfin_timer_irq);
117 * Should return useconds since last timer tick
119 static unsigned long gettimeoffset(void)
121 unsigned long offset;
122 unsigned long clocks_per_jiffy;
124 #ifdef CONFIG_TICK_SOURCE_SYSTMR0
125 clocks_per_jiffy = bfin_read_TIMER0_PERIOD();
126 offset = bfin_read_TIMER0_COUNTER() / \
127 (((clocks_per_jiffy + 1) * HZ) / USEC_PER_SEC);
129 if ((get_gptimer_status(0) & TIMER_STATUS_TIMIL0) && offset < (100000 / HZ / 2))
130 offset += (USEC_PER_SEC / HZ);
132 clocks_per_jiffy = bfin_read_TPERIOD();
133 offset = (clocks_per_jiffy - bfin_read_TCOUNT()) / \
134 (((clocks_per_jiffy + 1) * HZ) / USEC_PER_SEC);
136 /* Check if we just wrapped the counters and maybe missed a tick */
137 if ((bfin_read_ILAT() & (1 << IRQ_CORETMR))
138 && (offset < (100000 / HZ / 2)))
139 offset += (USEC_PER_SEC / HZ);
144 static inline int set_rtc_mmss(unsigned long nowtime)
150 * timer_interrupt() needs to keep up the real-time clock,
151 * as well as call the "do_timer()" routine every clocktick
153 #ifdef CONFIG_CORE_TIMER_IRQ_L1
154 irqreturn_t timer_interrupt(int irq, void *dummy)__attribute__((l1_text));
157 irqreturn_t timer_interrupt(int irq, void *dummy)
159 /* last time the cmos clock got updated */
160 static long last_rtc_update;
162 write_seqlock(&xtime_lock);
163 #ifdef CONFIG_TICK_SOURCE_SYSTMR0
164 if (get_gptimer_status(0) & TIMER_STATUS_TIMIL0) {
170 * If we have an externally synchronized Linux clock, then update
171 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
172 * called as close as possible to 500 ms before the new second starts.
176 xtime.tv_sec > last_rtc_update + 660 &&
177 (xtime.tv_nsec / NSEC_PER_USEC) >=
178 500000 - ((unsigned)TICK_SIZE) / 2
179 && (xtime.tv_nsec / NSEC_PER_USEC) <=
180 500000 + ((unsigned)TICK_SIZE) / 2) {
181 if (set_rtc_mmss(xtime.tv_sec) == 0)
182 last_rtc_update = xtime.tv_sec;
184 /* Do it again in 60s. */
185 last_rtc_update = xtime.tv_sec - 600;
187 #ifdef CONFIG_TICK_SOURCE_SYSTMR0
188 set_gptimer_status(0, TIMER_STATUS_TIMIL0);
191 write_sequnlock(&xtime_lock);
193 update_process_times(user_mode(get_irq_regs()));
194 profile_tick(CPU_PROFILING);
199 void __init time_init(void)
201 time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
203 #ifdef CONFIG_RTC_DRV_BFIN
204 /* [#2663] hack to filter junk RTC values that would cause
205 * userspace to have to deal with time values greater than
206 * 2^31 seconds (which uClibc cannot cope with yet)
208 if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
209 printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
210 bfin_write_RTC_STAT(0);
214 /* Initialize xtime. From now on, xtime is updated with timer interrupts */
215 xtime.tv_sec = secs_since_1970;
218 wall_to_monotonic.tv_sec = -xtime.tv_sec;
220 time_sched_init(timer_interrupt);
223 #ifndef CONFIG_GENERIC_TIME
224 void do_gettimeofday(struct timeval *tv)
228 unsigned long usec, sec;
231 seq = read_seqbegin_irqsave(&xtime_lock, flags);
232 usec = gettimeoffset();
234 usec += (xtime.tv_nsec / NSEC_PER_USEC);
236 while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
238 while (usec >= USEC_PER_SEC) {
239 usec -= USEC_PER_SEC;
246 EXPORT_SYMBOL(do_gettimeofday);
248 int do_settimeofday(struct timespec *tv)
250 time_t wtm_sec, sec = tv->tv_sec;
251 long wtm_nsec, nsec = tv->tv_nsec;
253 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
256 write_seqlock_irq(&xtime_lock);
258 * This is revolting. We need to set the xtime.tv_usec
259 * correctly. However, the value in this location is
260 * is value at the last tick.
261 * Discover what correction gettimeofday
262 * would have done, and then undo it!
264 nsec -= (gettimeoffset() * NSEC_PER_USEC);
266 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
267 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
269 set_normalized_timespec(&xtime, sec, nsec);
270 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
274 write_sequnlock_irq(&xtime_lock);
279 EXPORT_SYMBOL(do_settimeofday);
280 #endif /* !CONFIG_GENERIC_TIME */
283 * Scheduler clock - returns current time in nanosec units.
285 unsigned long long sched_clock(void)
287 return (unsigned long long)jiffies *(NSEC_PER_SEC / HZ);