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1da177e4 LT |
1 | /* |
2 | * arch/arm/mach-pxa/time.c | |
3 | * | |
4 | * Author: Nicolas Pitre | |
5 | * Created: Jun 15, 2001 | |
6 | * Copyright: MontaVista Software Inc. | |
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 | ||
1da177e4 LT |
13 | #include <linux/kernel.h> |
14 | #include <linux/init.h> | |
15 | #include <linux/delay.h> | |
16 | #include <linux/interrupt.h> | |
17 | #include <linux/time.h> | |
18 | #include <linux/signal.h> | |
19 | #include <linux/errno.h> | |
20 | #include <linux/sched.h> | |
c80204e5 | 21 | #include <linux/clocksource.h> |
1da177e4 LT |
22 | |
23 | #include <asm/system.h> | |
24 | #include <asm/hardware.h> | |
25 | #include <asm/io.h> | |
26 | #include <asm/leds.h> | |
27 | #include <asm/irq.h> | |
28 | #include <asm/mach/irq.h> | |
29 | #include <asm/mach/time.h> | |
30 | #include <asm/arch/pxa-regs.h> | |
31 | ||
32 | ||
33 | static inline unsigned long pxa_get_rtc_time(void) | |
34 | { | |
35 | return RCNR; | |
36 | } | |
37 | ||
38 | static int pxa_set_rtc(void) | |
39 | { | |
40 | unsigned long current_time = xtime.tv_sec; | |
41 | ||
42 | if (RTSR & RTSR_ALE) { | |
43 | /* make sure not to forward the clock over an alarm */ | |
44 | unsigned long alarm = RTAR; | |
45 | if (current_time >= alarm && alarm >= RCNR) | |
46 | return -ERESTARTSYS; | |
47 | } | |
48 | RCNR = current_time; | |
49 | return 0; | |
50 | } | |
51 | ||
5c53ff08 NP |
52 | #ifdef CONFIG_NO_IDLE_HZ |
53 | static unsigned long initial_match; | |
54 | static int match_posponed; | |
55 | #endif | |
56 | ||
1da177e4 | 57 | static irqreturn_t |
0cd61b68 | 58 | pxa_timer_interrupt(int irq, void *dev_id) |
1da177e4 LT |
59 | { |
60 | int next_match; | |
61 | ||
62 | write_seqlock(&xtime_lock); | |
63 | ||
5c53ff08 NP |
64 | #ifdef CONFIG_NO_IDLE_HZ |
65 | if (match_posponed) { | |
66 | match_posponed = 0; | |
67 | OSMR0 = initial_match; | |
68 | } | |
69 | #endif | |
70 | ||
1da177e4 LT |
71 | /* Loop until we get ahead of the free running timer. |
72 | * This ensures an exact clock tick count and time accuracy. | |
20e91268 NP |
73 | * Since IRQs are disabled at this point, coherence between |
74 | * lost_ticks(updated in do_timer()) and the match reg value is | |
75 | * ensured, hence we can use do_gettimeofday() from interrupt | |
76 | * handlers. | |
1da177e4 LT |
77 | * |
78 | * HACK ALERT: it seems that the PXA timer regs aren't updated right | |
79 | * away in all cases when a write occurs. We therefore compare with | |
80 | * 8 instead of 0 in the while() condition below to avoid missing a | |
81 | * match if OSCR has already reached the next OSMR value. | |
82 | * Experience has shown that up to 6 ticks are needed to work around | |
83 | * this problem, but let's use 8 to be conservative. Note that this | |
84 | * affect things only when the timer IRQ has been delayed by nearly | |
85 | * exactly one tick period which should be a pretty rare event. | |
86 | */ | |
87 | do { | |
0cd61b68 | 88 | timer_tick(); |
1da177e4 LT |
89 | OSSR = OSSR_M0; /* Clear match on timer 0 */ |
90 | next_match = (OSMR0 += LATCH); | |
91 | } while( (signed long)(next_match - OSCR) <= 8 ); | |
92 | ||
93 | write_sequnlock(&xtime_lock); | |
94 | ||
95 | return IRQ_HANDLED; | |
96 | } | |
97 | ||
98 | static struct irqaction pxa_timer_irq = { | |
99 | .name = "PXA Timer Tick", | |
b30fabad | 100 | .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, |
09b8b5f8 | 101 | .handler = pxa_timer_interrupt, |
1da177e4 LT |
102 | }; |
103 | ||
35108fb9 | 104 | static cycle_t pxa_get_cycles(void) |
c80204e5 SH |
105 | { |
106 | return OSCR; | |
107 | } | |
108 | ||
109 | static struct clocksource clocksource_pxa = { | |
110 | .name = "pxa_timer", | |
111 | .rating = 200, | |
112 | .read = pxa_get_cycles, | |
113 | .mask = CLOCKSOURCE_MASK(32), | |
114 | .shift = 20, | |
c66699a7 | 115 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, |
c80204e5 SH |
116 | }; |
117 | ||
1da177e4 LT |
118 | static void __init pxa_timer_init(void) |
119 | { | |
120 | struct timespec tv; | |
46ec0ce8 | 121 | unsigned long flags; |
1da177e4 LT |
122 | |
123 | set_rtc = pxa_set_rtc; | |
124 | ||
125 | tv.tv_nsec = 0; | |
126 | tv.tv_sec = pxa_get_rtc_time(); | |
127 | do_settimeofday(&tv); | |
128 | ||
5285eb57 | 129 | OIER = 0; /* disable any timer interrupts */ |
1da177e4 LT |
130 | OSSR = 0xf; /* clear status on all timers */ |
131 | setup_irq(IRQ_OST0, &pxa_timer_irq); | |
46ec0ce8 | 132 | local_irq_save(flags); |
5285eb57 | 133 | OIER = OIER_E0; /* enable match on timer 0 to cause interrupts */ |
46ec0ce8 NP |
134 | OSMR0 = OSCR + LATCH; /* set initial match */ |
135 | local_irq_restore(flags); | |
c80204e5 | 136 | |
35108fb9 NP |
137 | /* |
138 | * OSCR runs continuously on PXA and is not written to, | |
139 | * so we can use it as clock source directly. | |
c80204e5 SH |
140 | */ |
141 | clocksource_pxa.mult = | |
142 | clocksource_hz2mult(CLOCK_TICK_RATE, clocksource_pxa.shift); | |
143 | clocksource_register(&clocksource_pxa); | |
1da177e4 LT |
144 | } |
145 | ||
5c53ff08 NP |
146 | #ifdef CONFIG_NO_IDLE_HZ |
147 | static int pxa_dyn_tick_enable_disable(void) | |
148 | { | |
149 | /* nothing to do */ | |
150 | return 0; | |
151 | } | |
152 | ||
153 | static void pxa_dyn_tick_reprogram(unsigned long ticks) | |
154 | { | |
155 | if (ticks > 1) { | |
156 | initial_match = OSMR0; | |
157 | OSMR0 = initial_match + ticks * LATCH; | |
158 | match_posponed = 1; | |
159 | } | |
160 | } | |
161 | ||
162 | static irqreturn_t | |
0cd61b68 | 163 | pxa_dyn_tick_handler(int irq, void *dev_id) |
5c53ff08 NP |
164 | { |
165 | if (match_posponed) { | |
166 | match_posponed = 0; | |
167 | OSMR0 = initial_match; | |
168 | if ( (signed long)(initial_match - OSCR) <= 8 ) | |
0cd61b68 | 169 | return pxa_timer_interrupt(irq, dev_id); |
5c53ff08 NP |
170 | } |
171 | return IRQ_NONE; | |
172 | } | |
173 | ||
174 | static struct dyn_tick_timer pxa_dyn_tick = { | |
175 | .enable = pxa_dyn_tick_enable_disable, | |
176 | .disable = pxa_dyn_tick_enable_disable, | |
177 | .reprogram = pxa_dyn_tick_reprogram, | |
178 | .handler = pxa_dyn_tick_handler, | |
179 | }; | |
180 | #endif | |
181 | ||
1da177e4 LT |
182 | #ifdef CONFIG_PM |
183 | static unsigned long osmr[4], oier; | |
184 | ||
185 | static void pxa_timer_suspend(void) | |
186 | { | |
187 | osmr[0] = OSMR0; | |
188 | osmr[1] = OSMR1; | |
189 | osmr[2] = OSMR2; | |
190 | osmr[3] = OSMR3; | |
191 | oier = OIER; | |
192 | } | |
193 | ||
194 | static void pxa_timer_resume(void) | |
195 | { | |
196 | OSMR0 = osmr[0]; | |
197 | OSMR1 = osmr[1]; | |
198 | OSMR2 = osmr[2]; | |
199 | OSMR3 = osmr[3]; | |
200 | OIER = oier; | |
201 | ||
202 | /* | |
203 | * OSMR0 is the system timer: make sure OSCR is sufficiently behind | |
204 | */ | |
205 | OSCR = OSMR0 - LATCH; | |
206 | } | |
207 | #else | |
208 | #define pxa_timer_suspend NULL | |
209 | #define pxa_timer_resume NULL | |
210 | #endif | |
211 | ||
212 | struct sys_timer pxa_timer = { | |
213 | .init = pxa_timer_init, | |
214 | .suspend = pxa_timer_suspend, | |
215 | .resume = pxa_timer_resume, | |
5c53ff08 NP |
216 | #ifdef CONFIG_NO_IDLE_HZ |
217 | .dyn_tick = &pxa_dyn_tick, | |
218 | #endif | |
1da177e4 | 219 | }; |