// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.

#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/sched_clock.h>
#include <linux/cpu.h>
#include <linux/of_irq.h>
#include <asm/reg_ops.h>

#include "timer-of.h"

#define PTIM_CCVR       "cr<3, 14>"
#define PTIM_CTLR       "cr<0, 14>"
#define PTIM_LVR        "cr<6, 14>"
#define PTIM_TSR        "cr<1, 14>"

static int csky_mptimer_irq;

static int csky_mptimer_set_next_event(unsigned long delta,
                                       struct clock_event_device *ce)
{
        mtcr(PTIM_LVR, delta);

        return 0;
}

static int csky_mptimer_shutdown(struct clock_event_device *ce)
{
        mtcr(PTIM_CTLR, 0);

        return 0;
}

static int csky_mptimer_oneshot(struct clock_event_device *ce)
{
        mtcr(PTIM_CTLR, 1);

        return 0;
}

static int csky_mptimer_oneshot_stopped(struct clock_event_device *ce)
{
        mtcr(PTIM_CTLR, 0);

        return 0;
}

static DEFINE_PER_CPU(struct timer_of, csky_to) = {
        .flags                                  = TIMER_OF_CLOCK,
        .clkevt = {
                .rating                         = 300,
                .features                       = CLOCK_EVT_FEAT_PERCPU |
                                                  CLOCK_EVT_FEAT_ONESHOT,
                .set_state_shutdown             = csky_mptimer_shutdown,
                .set_state_oneshot              = csky_mptimer_oneshot,
                .set_state_oneshot_stopped      = csky_mptimer_oneshot_stopped,
                .set_next_event                 = csky_mptimer_set_next_event,
        },
};

static irqreturn_t csky_timer_interrupt(int irq, void *dev)
{
        struct timer_of *to = this_cpu_ptr(&csky_to);

        mtcr(PTIM_TSR, 0);

        to->clkevt.event_handler(&to->clkevt);

        return IRQ_HANDLED;
}

/*
 * clock event for percpu
 */
static int csky_mptimer_starting_cpu(unsigned int cpu)
{
        struct timer_of *to = per_cpu_ptr(&csky_to, cpu);

        to->clkevt.cpumask = cpumask_of(cpu);

        enable_percpu_irq(csky_mptimer_irq, 0);

        clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
                                        2, ULONG_MAX);

        return 0;
}

static int csky_mptimer_dying_cpu(unsigned int cpu)
{
        disable_percpu_irq(csky_mptimer_irq);

        return 0;
}

/*
 * clock source
 */
static u64 notrace sched_clock_read(void)
{
        return (u64)mfcr(PTIM_CCVR);
}

static u64 clksrc_read(struct clocksource *c)
{
        return (u64)mfcr(PTIM_CCVR);
}

struct clocksource csky_clocksource = {
        .name   = "csky",
        .rating = 400,
        .mask   = CLOCKSOURCE_MASK(32),
        .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
        .read   = clksrc_read,
};

static int __init csky_mptimer_init(struct device_node *np)
{
        int ret, cpu, cpu_rollback;
        struct timer_of *to = NULL;

        /*
         * Csky_mptimer is designed for C-SKY SMP multi-processors and
         * every core has it's own private irq and regs for clkevt and
         * clksrc.
         *
         * The regs is accessed by cpu instruction: mfcr/mtcr instead of
         * mmio map style. So we needn't mmio-address in dts, but we still
         * need to give clk and irq number.
         *
         * We use private irq for the mptimer and irq number is the same
         * for every core. So we use request_percpu_irq() in timer_of_init.
         */
        csky_mptimer_irq = irq_of_parse_and_map(np, 0);
        if (csky_mptimer_irq <= 0)
                return -EINVAL;

        ret = request_percpu_irq(csky_mptimer_irq, csky_timer_interrupt,
                                 "csky_mp_timer", &csky_to);
        if (ret)
                return -EINVAL;

        for_each_possible_cpu(cpu) {
                to = per_cpu_ptr(&csky_to, cpu);
                ret = timer_of_init(np, to);
                if (ret)
                        goto rollback;
        }

        clocksource_register_hz(&csky_clocksource, timer_of_rate(to));
        sched_clock_register(sched_clock_read, 32, timer_of_rate(to));

        ret = cpuhp_setup_state(CPUHP_AP_CSKY_TIMER_STARTING,
                                "clockevents/csky/timer:starting",
                                csky_mptimer_starting_cpu,
                                csky_mptimer_dying_cpu);
        if (ret)
                return -EINVAL;

        return 0;

rollback:
        for_each_possible_cpu(cpu_rollback) {
                if (cpu_rollback == cpu)
                        break;

                to = per_cpu_ptr(&csky_to, cpu_rollback);
                timer_of_cleanup(to);
        }
        return -EINVAL;
}
TIMER_OF_DECLARE(csky_mptimer, "csky,mptimer", csky_mptimer_init);