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Bryan Wu1394f032007-05-06 14:50:22 -07001/*
2 * File: arch/blackfin/kernel/time.c
3 * Based on: none - original work
4 * Author:
5 *
6 * Created:
7 * Description: This file contains the bfin-specific time handling details.
8 * Most of the stuff is located in the machine specific files.
9 *
10 * Modified:
11 * Copyright 2004-2006 Analog Devices Inc.
12 *
13 * Bugs: Enter bugs at http://blackfin.uclinux.org/
14 *
15 * This program is free software; you can redistribute it and/or modify
16 * it under the terms of the GNU General Public License as published by
17 * the Free Software Foundation; either version 2 of the License, or
18 * (at your option) any later version.
19 *
20 * This program is distributed in the hope that it will be useful,
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
23 * GNU General Public License for more details.
24 *
25 * You should have received a copy of the GNU General Public License
26 * along with this program; if not, see the file COPYING, or write
27 * to the Free Software Foundation, Inc.,
28 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
29 */
30
31#include <linux/module.h>
32#include <linux/profile.h>
33#include <linux/interrupt.h>
34#include <linux/time.h>
35#include <linux/irq.h>
36
37#include <asm/blackfin.h>
38
39/* This is an NTP setting */
40#define TICK_SIZE (tick_nsec / 1000)
41
42static void time_sched_init(irqreturn_t(*timer_routine)
43 (int, void *));
44static unsigned long gettimeoffset(void);
Bryan Wu1394f032007-05-06 14:50:22 -070045
46static struct irqaction bfin_timer_irq = {
47 .name = "BFIN Timer Tick",
48 .flags = IRQF_DISABLED
49};
50
51/*
52 * The way that the Blackfin core timer works is:
53 * - CCLK is divided by a programmable 8-bit pre-scaler (TSCALE)
54 * - Every time TSCALE ticks, a 32bit is counted down (TCOUNT)
55 *
56 * If you take the fastest clock (1ns, or 1GHz to make the math work easier)
57 * 10ms is 10,000,000 clock ticks, which fits easy into a 32-bit counter
58 * (32 bit counter is 4,294,967,296ns or 4.2 seconds) so, we don't need
59 * to use TSCALE, and program it to zero (which is pass CCLK through).
60 * If you feel like using it, try to keep HZ * TIMESCALE to some
61 * value that divides easy (like power of 2).
62 */
63
64#define TIME_SCALE 1
65
66static void
67time_sched_init(irqreturn_t(*timer_routine) (int, void *))
68{
69 u32 tcount;
70
71 /* power up the timer, but don't enable it just yet */
72 bfin_write_TCNTL(1);
73 CSYNC();
74
75 /*
76 * the TSCALE prescaler counter.
77 */
78 bfin_write_TSCALE((TIME_SCALE - 1));
79
80 tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
81 bfin_write_TPERIOD(tcount);
82 bfin_write_TCOUNT(tcount);
83
84 /* now enable the timer */
85 CSYNC();
86
87 bfin_write_TCNTL(7);
88
89 bfin_timer_irq.handler = (irq_handler_t)timer_routine;
90 /* call setup_irq instead of request_irq because request_irq calls
91 * kmalloc which has not been initialized yet
92 */
93 setup_irq(IRQ_CORETMR, &bfin_timer_irq);
94}
95
96/*
97 * Should return useconds since last timer tick
98 */
99static unsigned long gettimeoffset(void)
100{
101 unsigned long offset;
102 unsigned long clocks_per_jiffy;
103
104 clocks_per_jiffy = bfin_read_TPERIOD();
105 offset =
106 (clocks_per_jiffy -
107 bfin_read_TCOUNT()) / (((clocks_per_jiffy + 1) * HZ) /
108 USEC_PER_SEC);
109
110 /* Check if we just wrapped the counters and maybe missed a tick */
111 if ((bfin_read_ILAT() & (1 << IRQ_CORETMR))
112 && (offset < (100000 / HZ / 2)))
113 offset += (USEC_PER_SEC / HZ);
114
115 return offset;
116}
117
118static inline int set_rtc_mmss(unsigned long nowtime)
119{
120 return 0;
121}
122
123/*
124 * timer_interrupt() needs to keep up the real-time clock,
125 * as well as call the "do_timer()" routine every clocktick
126 */
127#ifdef CONFIG_CORE_TIMER_IRQ_L1
128irqreturn_t timer_interrupt(int irq, void *dummy)__attribute__((l1_text));
129#endif
130
131irqreturn_t timer_interrupt(int irq, void *dummy)
132{
133 /* last time the cmos clock got updated */
Mike Frysinger1f83b8f2007-07-12 22:58:21 +0800134 static long last_rtc_update;
Bryan Wu1394f032007-05-06 14:50:22 -0700135
136 write_seqlock(&xtime_lock);
137
138 do_timer(1);
Bryan Wu1394f032007-05-06 14:50:22 -0700139
140#ifndef CONFIG_SMP
141 update_process_times(user_mode(get_irq_regs()));
142#endif
143 profile_tick(CPU_PROFILING);
144
145 /*
146 * If we have an externally synchronized Linux clock, then update
147 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
148 * called as close as possible to 500 ms before the new second starts.
149 */
150
151 if (ntp_synced() &&
152 xtime.tv_sec > last_rtc_update + 660 &&
153 (xtime.tv_nsec / NSEC_PER_USEC) >=
154 500000 - ((unsigned)TICK_SIZE) / 2
155 && (xtime.tv_nsec / NSEC_PER_USEC) <=
156 500000 + ((unsigned)TICK_SIZE) / 2) {
157 if (set_rtc_mmss(xtime.tv_sec) == 0)
158 last_rtc_update = xtime.tv_sec;
159 else
160 /* Do it again in 60s. */
161 last_rtc_update = xtime.tv_sec - 600;
162 }
163 write_sequnlock(&xtime_lock);
164 return IRQ_HANDLED;
165}
166
167void __init time_init(void)
168{
169 time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
170
171#ifdef CONFIG_RTC_DRV_BFIN
172 /* [#2663] hack to filter junk RTC values that would cause
173 * userspace to have to deal with time values greater than
174 * 2^31 seconds (which uClibc cannot cope with yet)
175 */
176 if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
177 printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
178 bfin_write_RTC_STAT(0);
179 }
180#endif
181
182 /* Initialize xtime. From now on, xtime is updated with timer interrupts */
183 xtime.tv_sec = secs_since_1970;
184 xtime.tv_nsec = 0;
185
186 wall_to_monotonic.tv_sec = -xtime.tv_sec;
187
188 time_sched_init(timer_interrupt);
189}
190
191#ifndef CONFIG_GENERIC_TIME
192void do_gettimeofday(struct timeval *tv)
193{
194 unsigned long flags;
195 unsigned long seq;
196 unsigned long usec, sec;
197
198 do {
199 seq = read_seqbegin_irqsave(&xtime_lock, flags);
200 usec = gettimeoffset();
201 sec = xtime.tv_sec;
202 usec += (xtime.tv_nsec / NSEC_PER_USEC);
203 }
204 while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
205
206 while (usec >= USEC_PER_SEC) {
207 usec -= USEC_PER_SEC;
208 sec++;
209 }
210
211 tv->tv_sec = sec;
212 tv->tv_usec = usec;
213}
214EXPORT_SYMBOL(do_gettimeofday);
215
216int do_settimeofday(struct timespec *tv)
217{
218 time_t wtm_sec, sec = tv->tv_sec;
219 long wtm_nsec, nsec = tv->tv_nsec;
220
221 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
222 return -EINVAL;
223
224 write_seqlock_irq(&xtime_lock);
225 /*
226 * This is revolting. We need to set the xtime.tv_usec
227 * correctly. However, the value in this location is
228 * is value at the last tick.
229 * Discover what correction gettimeofday
230 * would have done, and then undo it!
231 */
232 nsec -= (gettimeoffset() * NSEC_PER_USEC);
233
234 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
235 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
236
237 set_normalized_timespec(&xtime, sec, nsec);
238 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
239
240 ntp_clear();
241
242 write_sequnlock_irq(&xtime_lock);
243 clock_was_set();
244
245 return 0;
246}
247EXPORT_SYMBOL(do_settimeofday);
248#endif /* !CONFIG_GENERIC_TIME */
249
250/*
251 * Scheduler clock - returns current time in nanosec units.
252 */
253unsigned long long sched_clock(void)
254{
255 return (unsigned long long)jiffies *(NSEC_PER_SEC / HZ);
256}