| 1 | |
| 2 | |
| 3 | * i8253.c 8253/PIT functions
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| 4 | *
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| 5 |
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| 6 | #include <linux/clockchips.h>
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| 7 | #include <linux/i8253.h>
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| 8 | #include <linux/export.h>
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| 9 | #include <linux/smp.h>
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| 10 | #include <linux/irq.h>
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| 11 |
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| 12 | #include <asm/time.h>
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| 13 |
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| 14 | static irqreturn_t timer_interrupt(int irq, void *dev_id)
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| 15 | {
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| 16 | i8253_clockevent.event_handler(&i8253_clockevent);
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| 17 |
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| 18 | return IRQ_HANDLED;
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| 19 | }
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| 20 |
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| 21 | void __init setup_pit_timer(void)
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| 22 | {
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| 23 | unsigned long flags = IRQF_NOBALANCING | IRQF_TIMER;
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| 24 |
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| 25 | clockevent_i8253_init(true);
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| 26 | if (request_irq(0, timer_interrupt, flags, "timer", NULL))
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| 27 | pr_err("Failed to request irq 0 (timer)\n");
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| 28 | }
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| 29 |
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| 30 | static int __init init_pit_clocksource(void)
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| 31 | {
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| 32 | if (num_possible_cpus() > 1 ||
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| 33 | !clockevent_state_periodic(&i8253_clockevent))
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| 34 | return 0;
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| 35 |
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| 36 | return clocksource_i8253_init();
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| 37 | }
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| 38 | arch_initcall(init_pit_clocksource);
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