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b920de1b DH |
1 | /* MN10300 Low level time management |
2 | * | |
3 | * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. | |
4 | * Written by David Howells (dhowells@redhat.com) | |
5 | * - Derived from arch/i386/kernel/time.c | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public Licence | |
9 | * as published by the Free Software Foundation; either version | |
10 | * 2 of the Licence, or (at your option) any later version. | |
11 | */ | |
12 | #include <linux/sched.h> | |
13 | #include <linux/kernel.h> | |
14 | #include <linux/interrupt.h> | |
15 | #include <linux/time.h> | |
16 | #include <linux/init.h> | |
17 | #include <linux/smp.h> | |
18 | #include <linux/profile.h> | |
19 | #include <asm/irq.h> | |
20 | #include <asm/div64.h> | |
21 | #include <asm/processor.h> | |
22 | #include <asm/intctl-regs.h> | |
23 | #include <asm/rtc.h> | |
24 | ||
25 | #ifdef CONFIG_MN10300_RTC | |
26 | unsigned long mn10300_ioclk; /* system I/O clock frequency */ | |
27 | unsigned long mn10300_iobclk; /* system I/O clock frequency */ | |
28 | unsigned long mn10300_tsc_per_HZ; /* number of ioclks per jiffy */ | |
29 | #endif /* CONFIG_MN10300_RTC */ | |
30 | ||
31 | static unsigned long mn10300_last_tsc; /* time-stamp counter at last time | |
32 | * interrupt occurred */ | |
33 | ||
34 | static irqreturn_t timer_interrupt(int irq, void *dev_id); | |
35 | ||
36 | static struct irqaction timer_irq = { | |
37 | .handler = timer_interrupt, | |
38 | .flags = IRQF_DISABLED | IRQF_SHARED | IRQF_TIMER, | |
39 | .mask = CPU_MASK_NONE, | |
40 | .name = "timer", | |
41 | }; | |
42 | ||
43 | /* | |
44 | * scheduler clock - returns current time in nanosec units. | |
45 | */ | |
46 | unsigned long long sched_clock(void) | |
47 | { | |
48 | union { | |
49 | unsigned long long l; | |
50 | u32 w[2]; | |
51 | } quot; | |
52 | ||
53 | quot.w[0] = mn10300_last_tsc - get_cycles(); | |
54 | quot.w[1] = 1000000000; | |
55 | ||
56 | asm("mulu %2,%3,%0,%1" | |
57 | : "=r"(quot.w[1]), "=r"(quot.w[0]) | |
58 | : "0"(quot.w[1]), "1"(quot.w[0]) | |
59 | : "cc"); | |
60 | ||
61 | do_div(quot.l, MN10300_TSCCLK); | |
62 | ||
63 | return quot.l; | |
64 | } | |
65 | ||
66 | /* | |
67 | * advance the kernel's time keeping clocks (xtime and jiffies) | |
68 | * - we use Timer 0 & 1 cascaded as a clock to nudge us the next time | |
69 | * there's a need to update | |
70 | */ | |
71 | static irqreturn_t timer_interrupt(int irq, void *dev_id) | |
72 | { | |
73 | unsigned tsc, elapse; | |
74 | ||
75 | write_seqlock(&xtime_lock); | |
76 | ||
77 | while (tsc = get_cycles(), | |
78 | elapse = mn10300_last_tsc - tsc, /* time elapsed since last | |
79 | * tick */ | |
80 | elapse > MN10300_TSC_PER_HZ | |
81 | ) { | |
82 | mn10300_last_tsc -= MN10300_TSC_PER_HZ; | |
83 | ||
84 | /* advance the kernel's time tracking system */ | |
85 | profile_tick(CPU_PROFILING); | |
86 | do_timer(1); | |
b920de1b DH |
87 | check_rtc_time(); |
88 | } | |
89 | ||
90 | write_sequnlock(&xtime_lock); | |
2b79aac9 DH |
91 | |
92 | update_process_times(user_mode(get_irq_regs())); | |
93 | ||
b920de1b DH |
94 | return IRQ_HANDLED; |
95 | } | |
96 | ||
97 | /* | |
98 | * initialise the various timers used by the main part of the kernel | |
99 | */ | |
100 | void __init time_init(void) | |
101 | { | |
102 | /* we need the prescalar running to be able to use IOCLK/8 | |
103 | * - IOCLK runs at 1/4 (ST5 open) or 1/8 (ST5 closed) internal CPU clock | |
104 | * - IOCLK runs at Fosc rate (crystal speed) | |
105 | */ | |
106 | TMPSCNT |= TMPSCNT_ENABLE; | |
107 | ||
108 | startup_timestamp_counter(); | |
109 | ||
110 | printk(KERN_INFO | |
111 | "timestamp counter I/O clock running at %lu.%02lu" | |
112 | " (calibrated against RTC)\n", | |
113 | MN10300_TSCCLK / 1000000, (MN10300_TSCCLK / 10000) % 100); | |
114 | ||
115 | xtime.tv_sec = get_initial_rtc_time(); | |
116 | xtime.tv_nsec = 0; | |
117 | ||
118 | mn10300_last_tsc = TMTSCBC; | |
119 | ||
120 | /* use timer 0 & 1 cascaded to tick at as close to HZ as possible */ | |
121 | setup_irq(TMJCIRQ, &timer_irq); | |
122 | ||
123 | set_intr_level(TMJCIRQ, TMJCICR_LEVEL); | |
124 | ||
125 | startup_jiffies_counter(); | |
126 | ||
127 | #ifdef CONFIG_MN10300_WD_TIMER | |
128 | /* start the watchdog timer */ | |
129 | watchdog_go(); | |
130 | #endif | |
131 | } |