/*
 * linux/arch/arm/mach-mmp/time.c
 *
 *   Support for clocksource and clockevents
 *
 * Copyright (C) 2008 Marvell International Ltd.
 * All rights reserved.
 *
 *   2008-04-11: Jason Chagas <Jason.chagas@marvell.com>
 *   2008-10-08: Bin Yang <bin.yang@marvell.com>
 *
 * The timers module actually includes three timers, each timer with up to
 * three match comparators. Timer #0 is used here in free-running mode as
 * the clock source, and match comparator #1 used as clock event device.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/clockchips.h>

#include <linux/io.h>
#include <linux/irq.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/sched_clock.h>

#include <mach/addr-map.h>
#include <mach/regs-timers.h>
#include <mach/regs-apbc.h>
#include <mach/irqs.h>
#include <mach/cputype.h>
#include <asm/mach/time.h>

#include "clock.h"

#ifdef CONFIG_CPU_MMP2
#define MMP_CLOCK_FREQ          6500000
#else
#define MMP_CLOCK_FREQ          3250000
#endif

#define TIMERS_VIRT_BASE        TIMERS1_VIRT_BASE

#define MAX_DELTA               (0xfffffffe)
#define MIN_DELTA               (16)

static void __iomem *mmp_timer_base = TIMERS_VIRT_BASE;

/*
 * FIXME: the timer needs some delay to stablize the counter capture
 */
static inline uint32_t timer_read(void)
{
        int delay = 100;

        __raw_writel(1, mmp_timer_base + TMR_CVWR(1));

        while (delay--)
                cpu_relax();

        return __raw_readl(mmp_timer_base + TMR_CVWR(1));
}

static u64 notrace mmp_read_sched_clock(void)
{
        return timer_read();
}

static irqreturn_t timer_interrupt(int irq, void *dev_id)
{
        struct clock_event_device *c = dev_id;

        /*
         * Clear pending interrupt status.
         */
        __raw_writel(0x01, mmp_timer_base + TMR_ICR(0));

        /*
         * Disable timer 0.
         */
        __raw_writel(0x02, mmp_timer_base + TMR_CER);

        c->event_handler(c);

        return IRQ_HANDLED;
}

static int timer_set_next_event(unsigned long delta,
                                struct clock_event_device *dev)
{
        unsigned long flags;

        local_irq_save(flags);

        /*
         * Disable timer 0.
         */
        __raw_writel(0x02, mmp_timer_base + TMR_CER);

        /*
         * Clear and enable timer match 0 interrupt.
         */
        __raw_writel(0x01, mmp_timer_base + TMR_ICR(0));
        __raw_writel(0x01, mmp_timer_base + TMR_IER(0));

        /*
         * Setup new clockevent timer value.
         */
        __raw_writel(delta - 1, mmp_timer_base + TMR_TN_MM(0, 0));

        /*
         * Enable timer 0.
         */
        __raw_writel(0x03, mmp_timer_base + TMR_CER);

        local_irq_restore(flags);

        return 0;
}

static void timer_set_mode(enum clock_event_mode mode,
                           struct clock_event_device *dev)
{
        unsigned long flags;

        local_irq_save(flags);
        switch (mode) {
        case CLOCK_EVT_MODE_ONESHOT:
        case CLOCK_EVT_MODE_UNUSED:
        case CLOCK_EVT_MODE_SHUTDOWN:
                /* disable the matching interrupt */
                __raw_writel(0x00, mmp_timer_base + TMR_IER(0));
                break;
        case CLOCK_EVT_MODE_RESUME:
        case CLOCK_EVT_MODE_PERIODIC:
                break;
        }
        local_irq_restore(flags);
}

static struct clock_event_device ckevt = {
        .name           = "clockevent",
        .features       = CLOCK_EVT_FEAT_ONESHOT,
        .rating         = 200,
        .set_next_event = timer_set_next_event,
        .set_mode       = timer_set_mode,
};

static cycle_t clksrc_read(struct clocksource *cs)
{
        return timer_read();
}

static struct clocksource cksrc = {
        .name           = "clocksource",
        .rating         = 200,
        .read           = clksrc_read,
        .mask           = CLOCKSOURCE_MASK(32),
        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
};

static void __init timer_config(void)
{
        uint32_t ccr = __raw_readl(mmp_timer_base + TMR_CCR);

        __raw_writel(0x0, mmp_timer_base + TMR_CER); /* disable */

        ccr &= (cpu_is_mmp2()) ? (TMR_CCR_CS_0(0) | TMR_CCR_CS_1(0)) :
                (TMR_CCR_CS_0(3) | TMR_CCR_CS_1(3));
        __raw_writel(ccr, mmp_timer_base + TMR_CCR);

        /* set timer 0 to periodic mode, and timer 1 to free-running mode */
        __raw_writel(0x2, mmp_timer_base + TMR_CMR);

        __raw_writel(0x1, mmp_timer_base + TMR_PLCR(0)); /* periodic */
        __raw_writel(0x7, mmp_timer_base + TMR_ICR(0));  /* clear status */
        __raw_writel(0x0, mmp_timer_base + TMR_IER(0));

        __raw_writel(0x0, mmp_timer_base + TMR_PLCR(1)); /* free-running */
        __raw_writel(0x7, mmp_timer_base + TMR_ICR(1));  /* clear status */
        __raw_writel(0x0, mmp_timer_base + TMR_IER(1));

        /* enable timer 1 counter */
        __raw_writel(0x2, mmp_timer_base + TMR_CER);
}

static struct irqaction timer_irq = {
        .name           = "timer",
        .flags          = IRQF_TIMER | IRQF_IRQPOLL,
        .handler        = timer_interrupt,
        .dev_id         = &ckevt,
};

void __init timer_init(int irq)
{
        timer_config();

        sched_clock_register(mmp_read_sched_clock, 32, MMP_CLOCK_FREQ);

        ckevt.cpumask = cpumask_of(0);

        setup_irq(irq, &timer_irq);

        clocksource_register_hz(&cksrc, MMP_CLOCK_FREQ);
        clockevents_config_and_register(&ckevt, MMP_CLOCK_FREQ,
                                        MIN_DELTA, MAX_DELTA);
}

#ifdef CONFIG_OF
static struct of_device_id mmp_timer_dt_ids[] = {
        { .compatible = "mrvl,mmp-timer", },
        {}
};

void __init mmp_dt_init_timer(void)
{
        struct device_node *np;
        int irq, ret;

        np = of_find_matching_node(NULL, mmp_timer_dt_ids);
        if (!np) {
                ret = -ENODEV;
                goto out;
        }

        irq = irq_of_parse_and_map(np, 0);
        if (!irq) {
                ret = -EINVAL;
                goto out;
        }
        mmp_timer_base = of_iomap(np, 0);
        if (!mmp_timer_base) {
                ret = -ENOMEM;
                goto out;
        }
        timer_init(irq);
        return;
out:
        pr_err("Failed to get timer from device tree with error:%d\n", ret);
}
#endif