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5a0015d6 CZ |
1 | /* |
2 | * arch/xtensa/kernel/time.c | |
3 | * | |
4 | * Timer and clock support. | |
5 | * | |
6 | * This file is subject to the terms and conditions of the GNU General Public | |
7 | * License. See the file "COPYING" in the main directory of this archive | |
8 | * for more details. | |
9 | * | |
10 | * Copyright (C) 2005 Tensilica Inc. | |
11 | * | |
12 | * Chris Zankel <chris@zankel.net> | |
13 | */ | |
14 | ||
5a0015d6 CZ |
15 | #include <linux/errno.h> |
16 | #include <linux/time.h> | |
fcc8f0f8 | 17 | #include <linux/clocksource.h> |
5a0015d6 CZ |
18 | #include <linux/interrupt.h> |
19 | #include <linux/module.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/irq.h> | |
22 | #include <linux/profile.h> | |
23 | #include <linux/delay.h> | |
24 | ||
25 | #include <asm/timex.h> | |
26 | #include <asm/platform.h> | |
27 | ||
5a0015d6 CZ |
28 | #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT |
29 | unsigned long ccount_per_jiffy; /* per 1/HZ */ | |
2b8aea74 | 30 | unsigned long nsec_per_ccount; /* nsec per ccount increment */ |
5a0015d6 CZ |
31 | #endif |
32 | ||
fcc8f0f8 JW |
33 | static cycle_t ccount_read(void) |
34 | { | |
35 | return (cycle_t)get_ccount(); | |
36 | } | |
37 | ||
38 | static struct clocksource ccount_clocksource = { | |
39 | .name = "ccount", | |
40 | .rating = 200, | |
41 | .read = ccount_read, | |
42 | .mask = CLOCKSOURCE_MASK(32), | |
43 | /* | |
44 | * With a shift of 22 the lower limit of the cpu clock is | |
45 | * 1MHz, where NSEC_PER_CCOUNT is 1000 or a bit less than | |
46 | * 2^10: Since we have 32 bits and the multiplicator can | |
47 | * already take up as much as 10 bits, this leaves us with | |
48 | * remaining upper 22 bits. | |
49 | */ | |
50 | .shift = 22, | |
51 | }; | |
52 | ||
fd43fe19 | 53 | static irqreturn_t timer_interrupt(int irq, void *dev_id); |
5a0015d6 CZ |
54 | static struct irqaction timer_irqaction = { |
55 | .handler = timer_interrupt, | |
85ac3ab2 | 56 | .flags = IRQF_DISABLED, |
5a0015d6 CZ |
57 | .name = "timer", |
58 | }; | |
59 | ||
60 | void __init time_init(void) | |
61 | { | |
d4f587c6 MS |
62 | /* FIXME: xtime&wall_to_monotonic are set in timekeeping_init. */ |
63 | read_persistent_clock(&xtime); | |
fcc8f0f8 JW |
64 | set_normalized_timespec(&wall_to_monotonic, |
65 | -xtime.tv_sec, -xtime.tv_nsec); | |
5a0015d6 | 66 | |
288a60cf | 67 | #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT |
5a0015d6 CZ |
68 | printk("Calibrating CPU frequency "); |
69 | platform_calibrate_ccount(); | |
70 | printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ), | |
71 | (int)(ccount_per_jiffy/(10000/HZ))%100); | |
72 | #endif | |
fcc8f0f8 JW |
73 | ccount_clocksource.mult = |
74 | clocksource_hz2mult(CCOUNT_PER_JIFFY * HZ, | |
75 | ccount_clocksource.shift); | |
76 | clocksource_register(&ccount_clocksource); | |
5a0015d6 CZ |
77 | |
78 | /* Initialize the linux timer interrupt. */ | |
79 | ||
80 | setup_irq(LINUX_TIMER_INT, &timer_irqaction); | |
81 | set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY); | |
82 | } | |
83 | ||
5a0015d6 CZ |
84 | /* |
85 | * The timer interrupt is called HZ times per second. | |
86 | */ | |
87 | ||
fd43fe19 | 88 | irqreturn_t timer_interrupt (int irq, void *dev_id) |
5a0015d6 CZ |
89 | { |
90 | ||
91 | unsigned long next; | |
92 | ||
93 | next = get_linux_timer(); | |
94 | ||
95 | again: | |
96 | while ((signed long)(get_ccount() - next) > 0) { | |
97 | ||
fd43fe19 | 98 | profile_tick(CPU_PROFILING); |
5a0015d6 | 99 | #ifndef CONFIG_SMP |
fd43fe19 | 100 | update_process_times(user_mode(get_irq_regs())); |
5a0015d6 CZ |
101 | #endif |
102 | ||
103 | write_seqlock(&xtime_lock); | |
104 | ||
2b8aea74 CZ |
105 | do_timer(1); /* Linux handler in kernel/timer.c */ |
106 | ||
107 | /* Note that writing CCOMPARE clears the interrupt. */ | |
108 | ||
5a0015d6 | 109 | next += CCOUNT_PER_JIFFY; |
2b8aea74 | 110 | set_linux_timer(next); |
5a0015d6 | 111 | |
5a0015d6 CZ |
112 | write_sequnlock(&xtime_lock); |
113 | } | |
114 | ||
2b8aea74 | 115 | /* Allow platform to do something useful (Wdog). */ |
5a0015d6 | 116 | |
2b8aea74 | 117 | platform_heartbeat(); |
5a0015d6 CZ |
118 | |
119 | /* Make sure we didn't miss any tick... */ | |
120 | ||
121 | if ((signed long)(get_ccount() - next) > 0) | |
122 | goto again; | |
123 | ||
5a0015d6 CZ |
124 | return IRQ_HANDLED; |
125 | } | |
126 | ||
127 | #ifndef CONFIG_GENERIC_CALIBRATE_DELAY | |
6c81c32f | 128 | void __cpuinit calibrate_delay(void) |
5a0015d6 CZ |
129 | { |
130 | loops_per_jiffy = CCOUNT_PER_JIFFY; | |
131 | printk("Calibrating delay loop (skipped)... " | |
132 | "%lu.%02lu BogoMIPS preset\n", | |
133 | loops_per_jiffy/(1000000/HZ), | |
134 | (loops_per_jiffy/(10000/HZ)) % 100); | |
135 | } | |
136 | #endif |