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1 | /* | |
2 | * arch/arm/mach-pxa/time.c | |
3 | * | |
4 | * PXA clocksource, clockevents, and OST interrupt handlers. | |
5 | * Copyright (c) 2007 by Bill Gatliff <bgat@billgatliff.com>. | |
6 | * | |
7 | * Derived from Nicolas Pitre's PXA timer handler Copyright (c) 2001 | |
8 | * by MontaVista Software, Inc. (Nico, your code rocks!) | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or modify | |
11 | * it under the terms of the GNU General Public License version 2 as | |
12 | * published by the Free Software Foundation. | |
13 | */ | |
14 | ||
15 | #include <linux/kernel.h> | |
16 | #include <linux/init.h> | |
17 | #include <linux/interrupt.h> | |
18 | #include <linux/clockchips.h> | |
19 | #include <linux/sched.h> | |
20 | #include <linux/cnt32_to_63.h> | |
21 | ||
22 | #include <asm/div64.h> | |
23 | #include <asm/mach/irq.h> | |
24 | #include <asm/mach/time.h> | |
25 | #include <mach/pxa-regs.h> | |
26 | #include <asm/mach-types.h> | |
27 | ||
28 | /* | |
29 | * This is PXA's sched_clock implementation. This has a resolution | |
30 | * of at least 308 ns and a maximum value of 208 days. | |
31 | * | |
32 | * The return value is guaranteed to be monotonic in that range as | |
33 | * long as there is always less than 582 seconds between successive | |
34 | * calls to sched_clock() which should always be the case in practice. | |
35 | */ | |
36 | ||
37 | #define OSCR2NS_SCALE_FACTOR 10 | |
38 | ||
39 | static unsigned long oscr2ns_scale; | |
40 | ||
41 | static void __init set_oscr2ns_scale(unsigned long oscr_rate) | |
42 | { | |
43 | unsigned long long v = 1000000000ULL << OSCR2NS_SCALE_FACTOR; | |
44 | do_div(v, oscr_rate); | |
45 | oscr2ns_scale = v; | |
46 | /* | |
47 | * We want an even value to automatically clear the top bit | |
48 | * returned by cnt32_to_63() without an additional run time | |
49 | * instruction. So if the LSB is 1 then round it up. | |
50 | */ | |
51 | if (oscr2ns_scale & 1) | |
52 | oscr2ns_scale++; | |
53 | } | |
54 | ||
55 | unsigned long long sched_clock(void) | |
56 | { | |
57 | unsigned long long v = cnt32_to_63(OSCR); | |
58 | return (v * oscr2ns_scale) >> OSCR2NS_SCALE_FACTOR; | |
59 | } | |
60 | ||
61 | ||
62 | #define MIN_OSCR_DELTA 16 | |
63 | ||
64 | static irqreturn_t | |
65 | pxa_ost0_interrupt(int irq, void *dev_id) | |
66 | { | |
67 | struct clock_event_device *c = dev_id; | |
68 | ||
69 | /* Disarm the compare/match, signal the event. */ | |
70 | OIER &= ~OIER_E0; | |
71 | OSSR = OSSR_M0; | |
72 | c->event_handler(c); | |
73 | ||
74 | return IRQ_HANDLED; | |
75 | } | |
76 | ||
77 | static int | |
78 | pxa_osmr0_set_next_event(unsigned long delta, struct clock_event_device *dev) | |
79 | { | |
80 | unsigned long flags, next, oscr; | |
81 | ||
82 | raw_local_irq_save(flags); | |
83 | OIER |= OIER_E0; | |
84 | next = OSCR + delta; | |
85 | OSMR0 = next; | |
86 | oscr = OSCR; | |
87 | raw_local_irq_restore(flags); | |
88 | ||
89 | return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0; | |
90 | } | |
91 | ||
92 | static void | |
93 | pxa_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *dev) | |
94 | { | |
95 | unsigned long irqflags; | |
96 | ||
97 | switch (mode) { | |
98 | case CLOCK_EVT_MODE_ONESHOT: | |
99 | raw_local_irq_save(irqflags); | |
100 | OIER &= ~OIER_E0; | |
101 | OSSR = OSSR_M0; | |
102 | raw_local_irq_restore(irqflags); | |
103 | break; | |
104 | ||
105 | case CLOCK_EVT_MODE_UNUSED: | |
106 | case CLOCK_EVT_MODE_SHUTDOWN: | |
107 | /* initializing, released, or preparing for suspend */ | |
108 | raw_local_irq_save(irqflags); | |
109 | OIER &= ~OIER_E0; | |
110 | OSSR = OSSR_M0; | |
111 | raw_local_irq_restore(irqflags); | |
112 | break; | |
113 | ||
114 | case CLOCK_EVT_MODE_RESUME: | |
115 | case CLOCK_EVT_MODE_PERIODIC: | |
116 | break; | |
117 | } | |
118 | } | |
119 | ||
120 | static struct clock_event_device ckevt_pxa_osmr0 = { | |
121 | .name = "osmr0", | |
122 | .features = CLOCK_EVT_FEAT_ONESHOT, | |
123 | .shift = 32, | |
124 | .rating = 200, | |
125 | .cpumask = CPU_MASK_CPU0, | |
126 | .set_next_event = pxa_osmr0_set_next_event, | |
127 | .set_mode = pxa_osmr0_set_mode, | |
128 | }; | |
129 | ||
130 | static cycle_t pxa_read_oscr(void) | |
131 | { | |
132 | return OSCR; | |
133 | } | |
134 | ||
135 | static struct clocksource cksrc_pxa_oscr0 = { | |
136 | .name = "oscr0", | |
137 | .rating = 200, | |
138 | .read = pxa_read_oscr, | |
139 | .mask = CLOCKSOURCE_MASK(32), | |
140 | .shift = 20, | |
141 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, | |
142 | }; | |
143 | ||
144 | static struct irqaction pxa_ost0_irq = { | |
145 | .name = "ost0", | |
146 | .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, | |
147 | .handler = pxa_ost0_interrupt, | |
148 | .dev_id = &ckevt_pxa_osmr0, | |
149 | }; | |
150 | ||
151 | static void __init pxa_timer_init(void) | |
152 | { | |
153 | unsigned long clock_tick_rate; | |
154 | ||
155 | OIER = 0; | |
156 | OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3; | |
157 | ||
158 | if (cpu_is_pxa25x()) | |
159 | clock_tick_rate = 3686400; | |
160 | else if (machine_is_mainstone()) | |
161 | clock_tick_rate = 3249600; | |
162 | else | |
163 | clock_tick_rate = 3250000; | |
164 | ||
165 | set_oscr2ns_scale(clock_tick_rate); | |
166 | ||
167 | ckevt_pxa_osmr0.mult = | |
168 | div_sc(clock_tick_rate, NSEC_PER_SEC, ckevt_pxa_osmr0.shift); | |
169 | ckevt_pxa_osmr0.max_delta_ns = | |
170 | clockevent_delta2ns(0x7fffffff, &ckevt_pxa_osmr0); | |
171 | ckevt_pxa_osmr0.min_delta_ns = | |
172 | clockevent_delta2ns(MIN_OSCR_DELTA * 2, &ckevt_pxa_osmr0) + 1; | |
173 | ||
174 | cksrc_pxa_oscr0.mult = | |
175 | clocksource_hz2mult(clock_tick_rate, cksrc_pxa_oscr0.shift); | |
176 | ||
177 | setup_irq(IRQ_OST0, &pxa_ost0_irq); | |
178 | ||
179 | clocksource_register(&cksrc_pxa_oscr0); | |
180 | clockevents_register_device(&ckevt_pxa_osmr0); | |
181 | } | |
182 | ||
183 | #ifdef CONFIG_PM | |
184 | static unsigned long osmr[4], oier, oscr; | |
185 | ||
186 | static void pxa_timer_suspend(void) | |
187 | { | |
188 | osmr[0] = OSMR0; | |
189 | osmr[1] = OSMR1; | |
190 | osmr[2] = OSMR2; | |
191 | osmr[3] = OSMR3; | |
192 | oier = OIER; | |
193 | oscr = OSCR; | |
194 | } | |
195 | ||
196 | static void pxa_timer_resume(void) | |
197 | { | |
198 | /* | |
199 | * Ensure that we have at least MIN_OSCR_DELTA between match | |
200 | * register 0 and the OSCR, to guarantee that we will receive | |
201 | * the one-shot timer interrupt. We adjust OSMR0 in preference | |
202 | * to OSCR to guarantee that OSCR is monotonically incrementing. | |
203 | */ | |
204 | if (osmr[0] - oscr < MIN_OSCR_DELTA) | |
205 | osmr[0] += MIN_OSCR_DELTA; | |
206 | ||
207 | OSMR0 = osmr[0]; | |
208 | OSMR1 = osmr[1]; | |
209 | OSMR2 = osmr[2]; | |
210 | OSMR3 = osmr[3]; | |
211 | OIER = oier; | |
212 | OSCR = oscr; | |
213 | } | |
214 | #else | |
215 | #define pxa_timer_suspend NULL | |
216 | #define pxa_timer_resume NULL | |
217 | #endif | |
218 | ||
219 | struct sys_timer pxa_timer = { | |
220 | .init = pxa_timer_init, | |
221 | .suspend = pxa_timer_suspend, | |
222 | .resume = pxa_timer_resume, | |
223 | }; |