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1da177e4 LT |
1 | /* |
2 | * linux/arch/arm26/kernel/time.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1995 Linus Torvalds | |
5 | * Modifications for ARM (C) 1994-2001 Russell King | |
6 | * Mods for ARM26 (C) 2003 Ian Molton | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License version 2 as | |
10 | * published by the Free Software Foundation. | |
11 | * | |
12 | * This file contains the ARM-specific time handling details: | |
13 | * reading the RTC at bootup, etc... | |
14 | * | |
15 | * 1994-07-02 Alan Modra | |
16 | * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime | |
17 | * 1998-12-20 Updated NTP code according to technical memorandum Jan '96 | |
18 | * "A Kernel Model for Precision Timekeeping" by Dave Mills | |
19 | */ | |
20 | ||
1da177e4 LT |
21 | #include <linux/module.h> |
22 | #include <linux/kernel.h> | |
23 | #include <linux/interrupt.h> | |
24 | #include <linux/time.h> | |
25 | #include <linux/init.h> | |
26 | #include <linux/smp.h> | |
27 | #include <linux/timex.h> | |
28 | #include <linux/errno.h> | |
29 | #include <linux/profile.h> | |
30 | ||
31 | #include <asm/hardware.h> | |
32 | #include <asm/io.h> | |
33 | #include <asm/irq.h> | |
34 | #include <asm/ioc.h> | |
35 | ||
1da177e4 LT |
36 | /* this needs a better home */ |
37 | DEFINE_SPINLOCK(rtc_lock); | |
38 | ||
39 | /* change this if you have some constant time drift */ | |
40 | #define USECS_PER_JIFFY (1000000/HZ) | |
41 | ||
42 | static int dummy_set_rtc(void) | |
43 | { | |
44 | return 0; | |
45 | } | |
46 | ||
47 | /* | |
48 | * hook for setting the RTC's idea of the current time. | |
49 | */ | |
50 | int (*set_rtc)(void) = dummy_set_rtc; | |
51 | ||
52 | /* | |
53 | * Get time offset based on IOCs timer. | |
54 | * FIXME - if this is called with interrutps off, why the shennanigans | |
55 | * below ? | |
56 | */ | |
57 | static unsigned long gettimeoffset(void) | |
58 | { | |
59 | unsigned int count1, count2, status; | |
60 | long offset; | |
61 | ||
62 | ioc_writeb (0, IOC_T0LATCH); | |
63 | barrier (); | |
64 | count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8); | |
65 | barrier (); | |
66 | status = ioc_readb(IOC_IRQREQA); | |
67 | barrier (); | |
68 | ioc_writeb (0, IOC_T0LATCH); | |
69 | barrier (); | |
70 | count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8); | |
71 | ||
72 | offset = count2; | |
73 | if (count2 < count1) { | |
74 | /* | |
75 | * We have not had an interrupt between reading count1 | |
76 | * and count2. | |
77 | */ | |
78 | if (status & (1 << 5)) | |
79 | offset -= LATCH; | |
80 | } else if (count2 > count1) { | |
81 | /* | |
82 | * We have just had another interrupt between reading | |
83 | * count1 and count2. | |
84 | */ | |
85 | offset -= LATCH; | |
86 | } | |
87 | ||
88 | offset = (LATCH - offset) * (tick_nsec / 1000); | |
89 | return (offset + LATCH/2) / LATCH; | |
90 | } | |
91 | ||
1da177e4 LT |
92 | static unsigned long next_rtc_update; |
93 | ||
94 | /* | |
95 | * If we have an externally synchronized linux clock, then update | |
96 | * CMOS clock accordingly every ~11 minutes. set_rtc() has to be | |
97 | * called as close as possible to 500 ms before the new second | |
98 | * starts. | |
99 | */ | |
100 | static inline void do_set_rtc(void) | |
101 | { | |
b149ee22 | 102 | if (!ntp_synced() || set_rtc == NULL) |
1da177e4 LT |
103 | return; |
104 | ||
105 | //FIXME - timespec.tv_sec is a time_t not unsigned long | |
106 | if (next_rtc_update && | |
107 | time_before((unsigned long)xtime.tv_sec, next_rtc_update)) | |
108 | return; | |
109 | ||
110 | if (xtime.tv_nsec < 500000000 - ((unsigned) tick_nsec >> 1) && | |
111 | xtime.tv_nsec >= 500000000 + ((unsigned) tick_nsec >> 1)) | |
112 | return; | |
113 | ||
114 | if (set_rtc()) | |
115 | /* | |
116 | * rtc update failed. Try again in 60s | |
117 | */ | |
118 | next_rtc_update = xtime.tv_sec + 60; | |
119 | else | |
120 | next_rtc_update = xtime.tv_sec + 660; | |
121 | } | |
122 | ||
123 | #define do_leds() | |
124 | ||
125 | void do_gettimeofday(struct timeval *tv) | |
126 | { | |
127 | unsigned long flags; | |
128 | unsigned long seq; | |
8ef38609 | 129 | unsigned long usec, sec; |
1da177e4 LT |
130 | |
131 | do { | |
132 | seq = read_seqbegin_irqsave(&xtime_lock, flags); | |
133 | usec = gettimeoffset(); | |
1da177e4 LT |
134 | sec = xtime.tv_sec; |
135 | usec += xtime.tv_nsec / 1000; | |
136 | } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); | |
137 | ||
138 | /* usec may have gone up a lot: be safe */ | |
139 | while (usec >= 1000000) { | |
140 | usec -= 1000000; | |
141 | sec++; | |
142 | } | |
143 | ||
144 | tv->tv_sec = sec; | |
145 | tv->tv_usec = usec; | |
146 | } | |
147 | ||
148 | EXPORT_SYMBOL(do_gettimeofday); | |
149 | ||
150 | int do_settimeofday(struct timespec *tv) | |
151 | { | |
152 | if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) | |
153 | return -EINVAL; | |
154 | ||
155 | write_seqlock_irq(&xtime_lock); | |
156 | /* | |
157 | * This is revolting. We need to set "xtime" correctly. However, the | |
158 | * value in this location is the value at the most recent update of | |
159 | * wall time. Discover what correction gettimeofday() would have | |
160 | * done, and then undo it! | |
161 | */ | |
8ef38609 | 162 | tv->tv_nsec -= 1000 * gettimeoffset(); |
1da177e4 LT |
163 | |
164 | while (tv->tv_nsec < 0) { | |
165 | tv->tv_nsec += NSEC_PER_SEC; | |
166 | tv->tv_sec--; | |
167 | } | |
168 | ||
169 | xtime.tv_sec = tv->tv_sec; | |
170 | xtime.tv_nsec = tv->tv_nsec; | |
b149ee22 | 171 | ntp_clear(); |
1da177e4 LT |
172 | write_sequnlock_irq(&xtime_lock); |
173 | clock_was_set(); | |
174 | return 0; | |
175 | } | |
176 | ||
177 | EXPORT_SYMBOL(do_settimeofday); | |
178 | ||
179 | static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) | |
180 | { | |
3171a030 | 181 | do_timer(1); |
1da177e4 LT |
182 | #ifndef CONFIG_SMP |
183 | update_process_times(user_mode(regs)); | |
184 | #endif | |
185 | do_set_rtc(); //FIME - EVERY timer IRQ? | |
186 | profile_tick(CPU_PROFILING, regs); | |
187 | return IRQ_HANDLED; //FIXME - is this right? | |
188 | } | |
189 | ||
190 | static struct irqaction timer_irq = { | |
191 | .name = "timer", | |
af0f4d36 | 192 | .flags = IRQF_DISABLED, |
1da177e4 LT |
193 | .handler = timer_interrupt, |
194 | }; | |
195 | ||
196 | extern void ioctime_init(void); | |
197 | ||
198 | /* | |
199 | * Set up timer interrupt. | |
200 | */ | |
201 | void __init time_init(void) | |
202 | { | |
203 | ioc_writeb(LATCH & 255, IOC_T0LTCHL); | |
204 | ioc_writeb(LATCH >> 8, IOC_T0LTCHH); | |
205 | ioc_writeb(0, IOC_T0GO); | |
206 | ||
207 | ||
208 | setup_irq(IRQ_TIMER, &timer_irq); | |
209 | } | |
210 |