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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 | ||
13 | #include <linux/config.h> | |
14 | #include <linux/kernel.h> | |
15 | #include <linux/init.h> | |
16 | #include <linux/delay.h> | |
17 | #include <linux/interrupt.h> | |
18 | #include <linux/time.h> | |
19 | #include <linux/signal.h> | |
20 | #include <linux/errno.h> | |
21 | #include <linux/sched.h> | |
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 | ||
52 | /* IRQs are disabled before entering here from do_gettimeofday() */ | |
53 | static unsigned long pxa_gettimeoffset (void) | |
54 | { | |
55 | long ticks_to_match, elapsed, usec; | |
56 | ||
57 | /* Get ticks before next timer match */ | |
58 | ticks_to_match = OSMR0 - OSCR; | |
59 | ||
60 | /* We need elapsed ticks since last match */ | |
61 | elapsed = LATCH - ticks_to_match; | |
62 | ||
63 | /* don't get fooled by the workaround in pxa_timer_interrupt() */ | |
64 | if (elapsed <= 0) | |
65 | return 0; | |
66 | ||
67 | /* Now convert them to usec */ | |
68 | usec = (unsigned long)(elapsed * (tick_nsec / 1000))/LATCH; | |
69 | ||
70 | return usec; | |
71 | } | |
72 | ||
5c53ff08 NP |
73 | #ifdef CONFIG_NO_IDLE_HZ |
74 | static unsigned long initial_match; | |
75 | static int match_posponed; | |
76 | #endif | |
77 | ||
1da177e4 LT |
78 | static irqreturn_t |
79 | pxa_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) | |
80 | { | |
81 | int next_match; | |
82 | ||
83 | write_seqlock(&xtime_lock); | |
84 | ||
5c53ff08 NP |
85 | #ifdef CONFIG_NO_IDLE_HZ |
86 | if (match_posponed) { | |
87 | match_posponed = 0; | |
88 | OSMR0 = initial_match; | |
89 | } | |
90 | #endif | |
91 | ||
1da177e4 LT |
92 | /* Loop until we get ahead of the free running timer. |
93 | * This ensures an exact clock tick count and time accuracy. | |
20e91268 NP |
94 | * Since IRQs are disabled at this point, coherence between |
95 | * lost_ticks(updated in do_timer()) and the match reg value is | |
96 | * ensured, hence we can use do_gettimeofday() from interrupt | |
97 | * handlers. | |
1da177e4 LT |
98 | * |
99 | * HACK ALERT: it seems that the PXA timer regs aren't updated right | |
100 | * away in all cases when a write occurs. We therefore compare with | |
101 | * 8 instead of 0 in the while() condition below to avoid missing a | |
102 | * match if OSCR has already reached the next OSMR value. | |
103 | * Experience has shown that up to 6 ticks are needed to work around | |
104 | * this problem, but let's use 8 to be conservative. Note that this | |
105 | * affect things only when the timer IRQ has been delayed by nearly | |
106 | * exactly one tick period which should be a pretty rare event. | |
107 | */ | |
108 | do { | |
109 | timer_tick(regs); | |
110 | OSSR = OSSR_M0; /* Clear match on timer 0 */ | |
111 | next_match = (OSMR0 += LATCH); | |
112 | } while( (signed long)(next_match - OSCR) <= 8 ); | |
113 | ||
114 | write_sequnlock(&xtime_lock); | |
115 | ||
116 | return IRQ_HANDLED; | |
117 | } | |
118 | ||
119 | static struct irqaction pxa_timer_irq = { | |
120 | .name = "PXA Timer Tick", | |
09b8b5f8 RK |
121 | .flags = SA_INTERRUPT | SA_TIMER, |
122 | .handler = pxa_timer_interrupt, | |
1da177e4 LT |
123 | }; |
124 | ||
125 | static void __init pxa_timer_init(void) | |
126 | { | |
127 | struct timespec tv; | |
128 | ||
129 | set_rtc = pxa_set_rtc; | |
130 | ||
131 | tv.tv_nsec = 0; | |
132 | tv.tv_sec = pxa_get_rtc_time(); | |
133 | do_settimeofday(&tv); | |
134 | ||
135 | OSMR0 = 0; /* set initial match at 0 */ | |
136 | OSSR = 0xf; /* clear status on all timers */ | |
137 | setup_irq(IRQ_OST0, &pxa_timer_irq); | |
138 | OIER |= OIER_E0; /* enable match on timer 0 to cause interrupts */ | |
139 | OSCR = 0; /* initialize free-running timer, force first match */ | |
140 | } | |
141 | ||
5c53ff08 NP |
142 | #ifdef CONFIG_NO_IDLE_HZ |
143 | static int pxa_dyn_tick_enable_disable(void) | |
144 | { | |
145 | /* nothing to do */ | |
146 | return 0; | |
147 | } | |
148 | ||
149 | static void pxa_dyn_tick_reprogram(unsigned long ticks) | |
150 | { | |
151 | if (ticks > 1) { | |
152 | initial_match = OSMR0; | |
153 | OSMR0 = initial_match + ticks * LATCH; | |
154 | match_posponed = 1; | |
155 | } | |
156 | } | |
157 | ||
158 | static irqreturn_t | |
159 | pxa_dyn_tick_handler(int irq, void *dev_id, struct pt_regs *regs) | |
160 | { | |
161 | if (match_posponed) { | |
162 | match_posponed = 0; | |
163 | OSMR0 = initial_match; | |
164 | if ( (signed long)(initial_match - OSCR) <= 8 ) | |
165 | return pxa_timer_interrupt(irq, dev_id, regs); | |
166 | } | |
167 | return IRQ_NONE; | |
168 | } | |
169 | ||
170 | static struct dyn_tick_timer pxa_dyn_tick = { | |
171 | .enable = pxa_dyn_tick_enable_disable, | |
172 | .disable = pxa_dyn_tick_enable_disable, | |
173 | .reprogram = pxa_dyn_tick_reprogram, | |
174 | .handler = pxa_dyn_tick_handler, | |
175 | }; | |
176 | #endif | |
177 | ||
1da177e4 LT |
178 | #ifdef CONFIG_PM |
179 | static unsigned long osmr[4], oier; | |
180 | ||
181 | static void pxa_timer_suspend(void) | |
182 | { | |
183 | osmr[0] = OSMR0; | |
184 | osmr[1] = OSMR1; | |
185 | osmr[2] = OSMR2; | |
186 | osmr[3] = OSMR3; | |
187 | oier = OIER; | |
188 | } | |
189 | ||
190 | static void pxa_timer_resume(void) | |
191 | { | |
192 | OSMR0 = osmr[0]; | |
193 | OSMR1 = osmr[1]; | |
194 | OSMR2 = osmr[2]; | |
195 | OSMR3 = osmr[3]; | |
196 | OIER = oier; | |
197 | ||
198 | /* | |
199 | * OSMR0 is the system timer: make sure OSCR is sufficiently behind | |
200 | */ | |
201 | OSCR = OSMR0 - LATCH; | |
202 | } | |
203 | #else | |
204 | #define pxa_timer_suspend NULL | |
205 | #define pxa_timer_resume NULL | |
206 | #endif | |
207 | ||
208 | struct sys_timer pxa_timer = { | |
209 | .init = pxa_timer_init, | |
210 | .suspend = pxa_timer_suspend, | |
211 | .resume = pxa_timer_resume, | |
212 | .offset = pxa_gettimeoffset, | |
5c53ff08 NP |
213 | #ifdef CONFIG_NO_IDLE_HZ |
214 | .dyn_tick = &pxa_dyn_tick, | |
215 | #endif | |
1da177e4 | 216 | }; |