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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/mips/kernel/cevt-ds1287.c
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// SPDX-License-Identifier: GPL-2.0-or-later

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/*

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 *  DS1287 clockevent driver

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 *

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 *  Copyright (C) 2008	Yoichi Yuasa <[email protected]>

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 */

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#include <linux/clockchips.h>

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#include <linux/init.h>

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#include <linux/interrupt.h>

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#include <linux/mc146818rtc.h>

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#include <linux/irq.h>

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#include <asm/ds1287.h>

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#include <asm/time.h>

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int ds1287_timer_state(void)

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{

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	return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0;

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}

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int ds1287_set_base_clock(unsigned int hz)

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{

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	u8 rate;

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	switch (hz) {

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	case 128:

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		rate = 0x9;

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		break;

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	case 256:

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		rate = 0x8;

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		break;

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	case 1024:

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		rate = 0x6;

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		break;

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	default:

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		return -EINVAL;

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	}

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	CMOS_WRITE(RTC_REF_CLCK_32KHZ | rate, RTC_REG_A);

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	return 0;

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}

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static int ds1287_set_next_event(unsigned long delta,

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				 struct clock_event_device *evt)

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{

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	return -EINVAL;

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}

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static int ds1287_shutdown(struct clock_event_device *evt)

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{

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	u8 val;

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	spin_lock(&rtc_lock);

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	val = CMOS_READ(RTC_REG_B);

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	val &= ~RTC_PIE;

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	CMOS_WRITE(val, RTC_REG_B);

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	spin_unlock(&rtc_lock);

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	return 0;

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}

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static int ds1287_set_periodic(struct clock_event_device *evt)

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{

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	u8 val;

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	spin_lock(&rtc_lock);

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	val = CMOS_READ(RTC_REG_B);

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	val |= RTC_PIE;

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	CMOS_WRITE(val, RTC_REG_B);

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	spin_unlock(&rtc_lock);

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	return 0;

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}

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static void ds1287_event_handler(struct clock_event_device *dev)

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{

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}

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static struct clock_event_device ds1287_clockevent = {

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	.name			= "ds1287",

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	.features		= CLOCK_EVT_FEAT_PERIODIC,

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	.set_next_event		= ds1287_set_next_event,

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	.set_state_shutdown	= ds1287_shutdown,

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	.set_state_periodic	= ds1287_set_periodic,

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	.tick_resume		= ds1287_shutdown,

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	.event_handler		= ds1287_event_handler,

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};

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static irqreturn_t ds1287_interrupt(int irq, void *dev_id)

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{

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	struct clock_event_device *cd = &ds1287_clockevent;

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	/* Ack the RTC interrupt. */

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	CMOS_READ(RTC_REG_C);

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	cd->event_handler(cd);

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	return IRQ_HANDLED;

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}

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int __init ds1287_clockevent_init(int irq)

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{

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	unsigned long flags = IRQF_PERCPU | IRQF_TIMER;

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	struct clock_event_device *cd;

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	cd = &ds1287_clockevent;

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	cd->rating = 100;

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	cd->irq = irq;

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	clockevent_set_clock(cd, 32768);

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	cd->max_delta_ns = clockevent_delta2ns(0x7fffffff, cd);

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	cd->max_delta_ticks = 0x7fffffff;

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	cd->min_delta_ns = clockevent_delta2ns(0x300, cd);

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	cd->min_delta_ticks = 0x300;

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	cd->cpumask = cpumask_of(0);

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	clockevents_register_device(&ds1287_clockevent);

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	return request_irq(irq, ds1287_interrupt, flags, "ds1287", NULL);

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}

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