time.c

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/*
 * linux/arch/arm/mach-w90x900/time.c
 *
 * Based on linux/arch/arm/plat-s3c24xx/time.c by Ben Dooks
 *
 * Copyright (c) 2009 Nuvoton technology corporation
 * All rights reserved.
 *
 * Wan ZongShun <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/leds.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>

#include <asm/mach-types.h>
#include <asm/mach/irq.h>
#include <asm/mach/time.h>

#include <mach/map.h>
#include <mach/regs-timer.h>

#include "nuc9xx.h"

#define RESETINT    0x1f
#define PERIOD      (0x01 << 27)
#define ONESHOT     (0x00 << 27)
#define COUNTEN     (0x01 << 30)
#define INTEN       (0x01 << 29)

#define TICKS_PER_SEC   100
#define PRESCALE    0x63 /* Divider = prescale + 1 */

#define TDR_SHIFT   24

static unsigned int timer0_load;

static void nuc900_clockevent_setmode(enum clock_event_mode mode,
        struct clock_event_device *clk)
{
    unsigned int val;

    val = __raw_readl(REG_TCSR0);
    val &= ~(0x03 << 27);

    switch (mode) {
    case CLOCK_EVT_MODE_PERIODIC:
        __raw_writel(timer0_load, REG_TICR0);
        val |= (PERIOD | COUNTEN | INTEN | PRESCALE);
        break;

    case CLOCK_EVT_MODE_ONESHOT:
        val |= (ONESHOT | COUNTEN | INTEN | PRESCALE);
        break;

    case CLOCK_EVT_MODE_UNUSED:
    case CLOCK_EVT_MODE_SHUTDOWN:
    case CLOCK_EVT_MODE_RESUME:
        break;
    }

    __raw_writel(val, REG_TCSR0);
}

static int nuc900_clockevent_setnextevent(unsigned long evt,
        struct clock_event_device *clk)
{
    unsigned int val;

    __raw_writel(evt, REG_TICR0);

    val = __raw_readl(REG_TCSR0);
    val |= (COUNTEN | INTEN | PRESCALE);
    __raw_writel(val, REG_TCSR0);

    return 0;
}

static struct clock_event_device nuc900_clockevent_device = {
    .name       = "nuc900-timer0",
    .shift      = 32,
    .features   = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
    .set_mode   = nuc900_clockevent_setmode,
    .set_next_event = nuc900_clockevent_setnextevent,
    .rating     = 300,
};

/*IRQ handler for the timer*/

static irqreturn_t nuc900_timer0_interrupt(int irq, void *dev_id)
{
    struct clock_event_device *evt = &nuc900_clockevent_device;

    __raw_writel(0x01, REG_TISR); /* clear TIF0 */

    evt->event_handler(evt);
    return IRQ_HANDLED;
}

static struct irqaction nuc900_timer0_irq = {
    .name       = "nuc900-timer0",
    .flags      = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
    .handler    = nuc900_timer0_interrupt,
};

static void __init nuc900_clockevents_init(void)
{
    unsigned int rate;
    struct clk *clk = clk_get(NULL, "timer0");

    BUG_ON(IS_ERR(clk));

    __raw_writel(0x00, REG_TCSR0);

    clk_enable(clk);
    rate = clk_get_rate(clk) / (PRESCALE + 1);

    timer0_load = (rate / TICKS_PER_SEC);

    __raw_writel(RESETINT, REG_TISR);
    setup_irq(IRQ_TIMER0, &nuc900_timer0_irq);

    nuc900_clockevent_device.mult = div_sc(rate, NSEC_PER_SEC,
                    nuc900_clockevent_device.shift);
    nuc900_clockevent_device.max_delta_ns = clockevent_delta2ns(0xffffffff,
                    &nuc900_clockevent_device);
    nuc900_clockevent_device.min_delta_ns = clockevent_delta2ns(0xf,
                    &nuc900_clockevent_device);
    nuc900_clockevent_device.cpumask = cpumask_of(0);

    clockevents_register_device(&nuc900_clockevent_device);
}

static void __init nuc900_clocksource_init(void)
{
    unsigned int val;
    unsigned int rate;
    struct clk *clk = clk_get(NULL, "timer1");

    BUG_ON(IS_ERR(clk));

    __raw_writel(0x00, REG_TCSR1);

    clk_enable(clk);
    rate = clk_get_rate(clk) / (PRESCALE + 1);

    __raw_writel(0xffffffff, REG_TICR1);

    val = __raw_readl(REG_TCSR1);
    val |= (COUNTEN | PERIOD | PRESCALE);
    __raw_writel(val, REG_TCSR1);

    clocksource_mmio_init(REG_TDR1, "nuc900-timer1", rate, 200,
        TDR_SHIFT, clocksource_mmio_readl_down);
}

static void __init nuc900_timer_init(void)
{
    nuc900_clocksource_init();
    nuc900_clockevents_init();
}

struct sys_timer nuc900_timer = {
    .init       = nuc900_timer_init,
};