// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2018 Socionext Inc.
 */

#include <linux/clk.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqreturn.h>
#include <linux/sched_clock.h>
#include "timer-of.h"

#define MLB_TMR_TMCSR_OFS       0x0
#define MLB_TMR_TMR_OFS         0x4
#define MLB_TMR_TMRLR1_OFS      0x8
#define MLB_TMR_TMRLR2_OFS      0xc
#define MLB_TMR_REGSZPCH        0x10

#define MLB_TMR_TMCSR_OUTL      BIT(5)
#define MLB_TMR_TMCSR_RELD      BIT(4)
#define MLB_TMR_TMCSR_INTE      BIT(3)
#define MLB_TMR_TMCSR_UF        BIT(2)
#define MLB_TMR_TMCSR_CNTE      BIT(1)
#define MLB_TMR_TMCSR_TRG       BIT(0)

#define MLB_TMR_TMCSR_CSL_DIV2  0
#define MLB_TMR_DIV_CNT         2

#define MLB_TMR_SRC_CH          1
#define MLB_TMR_EVT_CH          0

#define MLB_TMR_SRC_CH_OFS      (MLB_TMR_REGSZPCH * MLB_TMR_SRC_CH)
#define MLB_TMR_EVT_CH_OFS      (MLB_TMR_REGSZPCH * MLB_TMR_EVT_CH)

#define MLB_TMR_SRC_TMCSR_OFS   (MLB_TMR_SRC_CH_OFS + MLB_TMR_TMCSR_OFS)
#define MLB_TMR_SRC_TMR_OFS     (MLB_TMR_SRC_CH_OFS + MLB_TMR_TMR_OFS)
#define MLB_TMR_SRC_TMRLR1_OFS  (MLB_TMR_SRC_CH_OFS + MLB_TMR_TMRLR1_OFS)
#define MLB_TMR_SRC_TMRLR2_OFS  (MLB_TMR_SRC_CH_OFS + MLB_TMR_TMRLR2_OFS)

#define MLB_TMR_EVT_TMCSR_OFS   (MLB_TMR_EVT_CH_OFS + MLB_TMR_TMCSR_OFS)
#define MLB_TMR_EVT_TMR_OFS     (MLB_TMR_EVT_CH_OFS + MLB_TMR_TMR_OFS)
#define MLB_TMR_EVT_TMRLR1_OFS  (MLB_TMR_EVT_CH_OFS + MLB_TMR_TMRLR1_OFS)
#define MLB_TMR_EVT_TMRLR2_OFS  (MLB_TMR_EVT_CH_OFS + MLB_TMR_TMRLR2_OFS)

#define MLB_TIMER_RATING        500
#define MLB_TIMER_ONESHOT       0
#define MLB_TIMER_PERIODIC      1

static irqreturn_t mlb_timer_interrupt(int irq, void *dev_id)
{
        struct clock_event_device *clk = dev_id;
        struct timer_of *to = to_timer_of(clk);
        u32 val;

        val = readl_relaxed(timer_of_base(to) + MLB_TMR_EVT_TMCSR_OFS);
        val &= ~MLB_TMR_TMCSR_UF;
        writel_relaxed(val, timer_of_base(to) + MLB_TMR_EVT_TMCSR_OFS);

        clk->event_handler(clk);

        return IRQ_HANDLED;
}

static void mlb_evt_timer_start(struct timer_of *to, bool periodic)
{
        u32 val = MLB_TMR_TMCSR_CSL_DIV2;

        val |= MLB_TMR_TMCSR_CNTE | MLB_TMR_TMCSR_TRG | MLB_TMR_TMCSR_INTE;
        if (periodic)
                val |= MLB_TMR_TMCSR_RELD;
        writel_relaxed(val, timer_of_base(to) + MLB_TMR_EVT_TMCSR_OFS);
}

static void mlb_evt_timer_stop(struct timer_of *to)
{
        u32 val = readl_relaxed(timer_of_base(to) + MLB_TMR_EVT_TMCSR_OFS);

        val &= ~MLB_TMR_TMCSR_CNTE;
        writel_relaxed(val, timer_of_base(to) + MLB_TMR_EVT_TMCSR_OFS);
}

static void mlb_evt_timer_register_count(struct timer_of *to, unsigned long cnt)
{
        writel_relaxed(cnt, timer_of_base(to) + MLB_TMR_EVT_TMRLR1_OFS);
}

static int mlb_set_state_periodic(struct clock_event_device *clk)
{
        struct timer_of *to = to_timer_of(clk);

        mlb_evt_timer_stop(to);
        mlb_evt_timer_register_count(to, to->of_clk.period);
        mlb_evt_timer_start(to, MLB_TIMER_PERIODIC);
        return 0;
}

static int mlb_set_state_oneshot(struct clock_event_device *clk)
{
        struct timer_of *to = to_timer_of(clk);

        mlb_evt_timer_stop(to);
        mlb_evt_timer_start(to, MLB_TIMER_ONESHOT);
        return 0;
}

static int mlb_set_state_shutdown(struct clock_event_device *clk)
{
        struct timer_of *to = to_timer_of(clk);

        mlb_evt_timer_stop(to);
        return 0;
}

static int mlb_clkevt_next_event(unsigned long event,
                                   struct clock_event_device *clk)
{
        struct timer_of *to = to_timer_of(clk);

        mlb_evt_timer_stop(to);
        mlb_evt_timer_register_count(to, event);
        mlb_evt_timer_start(to, MLB_TIMER_ONESHOT);
        return 0;
}

static int mlb_config_clock_source(struct timer_of *to)
{
        u32 val = MLB_TMR_TMCSR_CSL_DIV2;

        writel_relaxed(val, timer_of_base(to) + MLB_TMR_SRC_TMCSR_OFS);
        writel_relaxed(~0, timer_of_base(to) + MLB_TMR_SRC_TMRLR1_OFS);
        writel_relaxed(~0, timer_of_base(to) + MLB_TMR_SRC_TMRLR2_OFS);
        val |= MLB_TMR_TMCSR_RELD | MLB_TMR_TMCSR_CNTE | MLB_TMR_TMCSR_TRG;
        writel_relaxed(val, timer_of_base(to) + MLB_TMR_SRC_TMCSR_OFS);
        return 0;
}

static int mlb_config_clock_event(struct timer_of *to)
{
        writel_relaxed(0, timer_of_base(to) + MLB_TMR_EVT_TMCSR_OFS);
        return 0;
}

static struct timer_of to = {
        .flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,

        .clkevt = {
                .name = "mlb-clkevt",
                .rating = MLB_TIMER_RATING,
                .cpumask = cpu_possible_mask,
                .features = CLOCK_EVT_FEAT_DYNIRQ | CLOCK_EVT_FEAT_ONESHOT,
                .set_state_oneshot = mlb_set_state_oneshot,
                .set_state_periodic = mlb_set_state_periodic,
                .set_state_shutdown = mlb_set_state_shutdown,
                .set_next_event = mlb_clkevt_next_event,
        },

        .of_irq = {
                .flags = IRQF_TIMER | IRQF_IRQPOLL,
                .handler = mlb_timer_interrupt,
        },
};

static u64 notrace mlb_timer_sched_read(void)
{
        return ~readl_relaxed(timer_of_base(&to) + MLB_TMR_SRC_TMR_OFS);
}

static int __init mlb_timer_init(struct device_node *node)
{
        int ret;
        unsigned long rate;

        ret = timer_of_init(node, &to);
        if (ret)
                return ret;

        rate = timer_of_rate(&to) / MLB_TMR_DIV_CNT;
        mlb_config_clock_source(&to);
        clocksource_mmio_init(timer_of_base(&to) + MLB_TMR_SRC_TMR_OFS,
                node->name, rate, MLB_TIMER_RATING, 32,
                clocksource_mmio_readl_down);
        sched_clock_register(mlb_timer_sched_read, 32, rate);
        mlb_config_clock_event(&to);
        clockevents_config_and_register(&to.clkevt, timer_of_rate(&to), 15,
                0xffffffff);
        return 0;
}
TIMER_OF_DECLARE(mlb_peritimer, "socionext,milbeaut-timer",
                mlb_timer_init);