/*
 * arch/xtensa/kernel/time.c
 *
 * Timer and clock support.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2005 Tensilica Inc.
 *
 * Chris Zankel <chris@zankel.net>
 */

#include <linux/clk.h>
#include <linux/of_clk.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/profile.h>
#include <linux/delay.h>
#include <linux/irqdomain.h>
#include <linux/sched_clock.h>

#include <asm/timex.h>
#include <asm/platform.h>

unsigned long ccount_freq;              /* ccount Hz */
EXPORT_SYMBOL(ccount_freq);

static u64 ccount_read(struct clocksource *cs)
{
        return (u64)get_ccount();
}

static u64 notrace ccount_sched_clock_read(void)
{
        return get_ccount();
}

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

struct ccount_timer {
        struct clock_event_device evt;
        int irq_enabled;
        char name[24];
};

static int ccount_timer_set_next_event(unsigned long delta,
                struct clock_event_device *dev)
{
        unsigned long flags, next;
        int ret = 0;

        local_irq_save(flags);
        next = get_ccount() + delta;
        set_linux_timer(next);
        if (next - get_ccount() > delta)
                ret = -ETIME;
        local_irq_restore(flags);

        return ret;
}

/*
 * There is no way to disable the timer interrupt at the device level,
 * only at the intenable register itself. Since enable_irq/disable_irq
 * calls are nested, we need to make sure that these calls are
 * balanced.
 */
static int ccount_timer_shutdown(struct clock_event_device *evt)
{
        struct ccount_timer *timer =
                container_of(evt, struct ccount_timer, evt);

        if (timer->irq_enabled) {
                disable_irq_nosync(evt->irq);
                timer->irq_enabled = 0;
        }
        return 0;
}

static int ccount_timer_set_oneshot(struct clock_event_device *evt)
{
        struct ccount_timer *timer =
                container_of(evt, struct ccount_timer, evt);

        if (!timer->irq_enabled) {
                enable_irq(evt->irq);
                timer->irq_enabled = 1;
        }
        return 0;
}

static DEFINE_PER_CPU(struct ccount_timer, ccount_timer) = {
        .evt = {
                .features = CLOCK_EVT_FEAT_ONESHOT,
                .rating = 300,
                .set_next_event = ccount_timer_set_next_event,
                .set_state_shutdown = ccount_timer_shutdown,
                .set_state_oneshot = ccount_timer_set_oneshot,
                .tick_resume = ccount_timer_set_oneshot,
        },
};

static irqreturn_t timer_interrupt(int irq, void *dev_id)
{
        struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt;

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

void local_timer_setup(unsigned cpu)
{
        struct ccount_timer *timer = &per_cpu(ccount_timer, cpu);
        struct clock_event_device *clockevent = &timer->evt;

        timer->irq_enabled = 1;
        snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu);
        clockevent->name = timer->name;
        clockevent->cpumask = cpumask_of(cpu);
        clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
        if (WARN(!clockevent->irq, "error: can't map timer irq"))
                return;
        clockevents_config_and_register(clockevent, ccount_freq,
                                        0xf, 0xffffffff);
}

#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
#ifdef CONFIG_OF
static void __init calibrate_ccount(void)
{
        struct device_node *cpu;
        struct clk *clk;

        cpu = of_find_compatible_node(NULL, NULL, "cdns,xtensa-cpu");
        if (cpu) {
                clk = of_clk_get(cpu, 0);
                of_node_put(cpu);
                if (!IS_ERR(clk)) {
                        ccount_freq = clk_get_rate(clk);
                        return;
                } else {
                        pr_warn("%s: CPU input clock not found\n",
                                __func__);
                }
        } else {
                pr_warn("%s: CPU node not found in the device tree\n",
                        __func__);
        }

        platform_calibrate_ccount();
}
#else
static inline void calibrate_ccount(void)
{
        platform_calibrate_ccount();
}
#endif
#endif

void __init time_init(void)
{
        int irq;

        of_clk_init(NULL);
#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
        pr_info("Calibrating CPU frequency ");
        calibrate_ccount();
        pr_cont("%d.%02d MHz\n",
                (int)ccount_freq / 1000000,
                (int)(ccount_freq / 10000) % 100);
#else
        ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL;
#endif
        WARN(!ccount_freq,
             "%s: CPU clock frequency is not set up correctly\n",
             __func__);
        clocksource_register_hz(&ccount_clocksource, ccount_freq);
        local_timer_setup(0);
        irq = this_cpu_ptr(&ccount_timer)->evt.irq;
        if (request_irq(irq, timer_interrupt, IRQF_TIMER, "timer", NULL))
                pr_err("Failed to request irq %d (timer)\n", irq);
        sched_clock_register(ccount_sched_clock_read, 32, ccount_freq);
        timer_probe();
}

#ifndef CONFIG_GENERIC_CALIBRATE_DELAY
void calibrate_delay(void)
{
        loops_per_jiffy = ccount_freq / HZ;
        pr_info("Calibrating delay loop (skipped)... %lu.%02lu BogoMIPS preset\n",
                loops_per_jiffy / (1000000 / HZ),
                (loops_per_jiffy / (10000 / HZ)) % 100);
}
#endif