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b920de1b DH |
1 | /* MN10300 Low level time management |
2 | * | |
08ec3c2d | 3 | * Copyright (C) 2007-2008 Red Hat, Inc. All Rights Reserved. |
b920de1b DH |
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> | |
08ec3c2d | 19 | #include <linux/cnt32_to_63.h> |
b920de1b DH |
20 | #include <asm/irq.h> |
21 | #include <asm/div64.h> | |
22 | #include <asm/processor.h> | |
23 | #include <asm/intctl-regs.h> | |
24 | #include <asm/rtc.h> | |
368dd5ac | 25 | #include "internal.h" |
b920de1b DH |
26 | |
27 | static unsigned long mn10300_last_tsc; /* time-stamp counter at last time | |
28 | * interrupt occurred */ | |
29 | ||
30 | static irqreturn_t timer_interrupt(int irq, void *dev_id); | |
31 | ||
32 | static struct irqaction timer_irq = { | |
33 | .handler = timer_interrupt, | |
34 | .flags = IRQF_DISABLED | IRQF_SHARED | IRQF_TIMER, | |
b920de1b DH |
35 | .name = "timer", |
36 | }; | |
37 | ||
08ec3c2d DH |
38 | static unsigned long sched_clock_multiplier; |
39 | ||
b920de1b DH |
40 | /* |
41 | * scheduler clock - returns current time in nanosec units. | |
42 | */ | |
43 | unsigned long long sched_clock(void) | |
44 | { | |
45 | union { | |
08ec3c2d DH |
46 | unsigned long long ll; |
47 | unsigned l[2]; | |
48 | } tsc64, result; | |
49 | unsigned long tsc, tmp; | |
50 | unsigned product[3]; /* 96-bit intermediate value */ | |
51 | ||
3b950de9 DH |
52 | /* cnt32_to_63() is not safe with preemption */ |
53 | preempt_disable(); | |
54 | ||
08ec3c2d DH |
55 | /* read the TSC value |
56 | */ | |
57 | tsc = 0 - get_cycles(); /* get_cycles() counts down */ | |
b920de1b | 58 | |
08ec3c2d DH |
59 | /* expand to 64-bits. |
60 | * - sched_clock() must be called once a minute or better or the | |
61 | * following will go horribly wrong - see cnt32_to_63() | |
62 | */ | |
63 | tsc64.ll = cnt32_to_63(tsc) & 0x7fffffffffffffffULL; | |
b920de1b | 64 | |
3b950de9 DH |
65 | preempt_enable(); |
66 | ||
08ec3c2d DH |
67 | /* scale the 64-bit TSC value to a nanosecond value via a 96-bit |
68 | * intermediate | |
69 | */ | |
70 | asm("mulu %2,%0,%3,%0 \n" /* LSW * mult -> 0:%3:%0 */ | |
71 | "mulu %2,%1,%2,%1 \n" /* MSW * mult -> %2:%1:0 */ | |
72 | "add %3,%1 \n" | |
73 | "addc 0,%2 \n" /* result in %2:%1:%0 */ | |
74 | : "=r"(product[0]), "=r"(product[1]), "=r"(product[2]), "=r"(tmp) | |
75 | : "0"(tsc64.l[0]), "1"(tsc64.l[1]), "2"(sched_clock_multiplier) | |
b920de1b DH |
76 | : "cc"); |
77 | ||
08ec3c2d DH |
78 | result.l[0] = product[1] << 16 | product[0] >> 16; |
79 | result.l[1] = product[2] << 16 | product[1] >> 16; | |
b920de1b | 80 | |
08ec3c2d DH |
81 | return result.ll; |
82 | } | |
83 | ||
84 | /* | |
85 | * initialise the scheduler clock | |
86 | */ | |
87 | static void __init mn10300_sched_clock_init(void) | |
88 | { | |
89 | sched_clock_multiplier = | |
90 | __muldiv64u(NSEC_PER_SEC, 1 << 16, MN10300_TSCCLK); | |
b920de1b DH |
91 | } |
92 | ||
368dd5ac AT |
93 | /** |
94 | * local_timer_interrupt - Local timer interrupt handler | |
95 | * | |
96 | * Handle local timer interrupts for this CPU. They may have been propagated | |
97 | * to this CPU from the CPU that actually gets them by way of an IPI. | |
98 | */ | |
99 | irqreturn_t local_timer_interrupt(void) | |
100 | { | |
101 | profile_tick(CPU_PROFILING); | |
102 | update_process_times(user_mode(get_irq_regs())); | |
103 | return IRQ_HANDLED; | |
104 | } | |
105 | ||
b920de1b DH |
106 | /* |
107 | * advance the kernel's time keeping clocks (xtime and jiffies) | |
108 | * - we use Timer 0 & 1 cascaded as a clock to nudge us the next time | |
109 | * there's a need to update | |
110 | */ | |
111 | static irqreturn_t timer_interrupt(int irq, void *dev_id) | |
112 | { | |
113 | unsigned tsc, elapse; | |
368dd5ac | 114 | irqreturn_t ret; |
b920de1b DH |
115 | |
116 | write_seqlock(&xtime_lock); | |
117 | ||
118 | while (tsc = get_cycles(), | |
119 | elapse = mn10300_last_tsc - tsc, /* time elapsed since last | |
120 | * tick */ | |
121 | elapse > MN10300_TSC_PER_HZ | |
122 | ) { | |
123 | mn10300_last_tsc -= MN10300_TSC_PER_HZ; | |
124 | ||
125 | /* advance the kernel's time tracking system */ | |
b920de1b | 126 | do_timer(1); |
b920de1b DH |
127 | } |
128 | ||
129 | write_sequnlock(&xtime_lock); | |
2b79aac9 | 130 | |
368dd5ac AT |
131 | ret = local_timer_interrupt(); |
132 | #ifdef CONFIG_SMP | |
133 | send_IPI_allbutself(LOCAL_TIMER_IPI); | |
134 | #endif | |
135 | return ret; | |
b920de1b DH |
136 | } |
137 | ||
138 | /* | |
139 | * initialise the various timers used by the main part of the kernel | |
140 | */ | |
141 | void __init time_init(void) | |
142 | { | |
143 | /* we need the prescalar running to be able to use IOCLK/8 | |
144 | * - IOCLK runs at 1/4 (ST5 open) or 1/8 (ST5 closed) internal CPU clock | |
145 | * - IOCLK runs at Fosc rate (crystal speed) | |
146 | */ | |
147 | TMPSCNT |= TMPSCNT_ENABLE; | |
148 | ||
149 | startup_timestamp_counter(); | |
150 | ||
151 | printk(KERN_INFO | |
152 | "timestamp counter I/O clock running at %lu.%02lu" | |
153 | " (calibrated against RTC)\n", | |
154 | MN10300_TSCCLK / 1000000, (MN10300_TSCCLK / 10000) % 100); | |
155 | ||
b920de1b DH |
156 | mn10300_last_tsc = TMTSCBC; |
157 | ||
158 | /* use timer 0 & 1 cascaded to tick at as close to HZ as possible */ | |
159 | setup_irq(TMJCIRQ, &timer_irq); | |
160 | ||
368dd5ac | 161 | set_intr_level(TMJCIRQ, NUM2GxICR_LEVEL(CONFIG_TIMER_IRQ_LEVEL)); |
b920de1b DH |
162 | |
163 | startup_jiffies_counter(); | |
164 | ||
165 | #ifdef CONFIG_MN10300_WD_TIMER | |
166 | /* start the watchdog timer */ | |
167 | watchdog_go(); | |
168 | #endif | |
08ec3c2d DH |
169 | |
170 | mn10300_sched_clock_init(); | |
b920de1b | 171 | } |