// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Mediatek SoCs General-Purpose Timer handling.
 *
 * Copyright (C) 2014 Matthias Brugger
 *
 * Matthias Brugger <matthias.bgg@gmail.com>
 */

#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt

#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/interrupt.h>
#include <linux/irqreturn.h>
#include <linux/sched_clock.h>
#include <linux/slab.h>
#include "timer-of.h"

#define TIMER_CLK_EVT           (1)
#define TIMER_CLK_SRC           (2)

#define TIMER_SYNC_TICKS        (3)

/* gpt */
#define GPT_IRQ_EN_REG          0x00
#define GPT_IRQ_ENABLE(val)     BIT((val) - 1)
#define GPT_IRQ_ACK_REG         0x08
#define GPT_IRQ_ACK(val)        BIT((val) - 1)

#define GPT_CTRL_REG(val)       (0x10 * (val))
#define GPT_CTRL_OP(val)        (((val) & 0x3) << 4)
#define GPT_CTRL_OP_ONESHOT     (0)
#define GPT_CTRL_OP_REPEAT      (1)
#define GPT_CTRL_OP_FREERUN     (3)
#define GPT_CTRL_CLEAR          (2)
#define GPT_CTRL_ENABLE         (1)
#define GPT_CTRL_DISABLE        (0)

#define GPT_CLK_REG(val)        (0x04 + (0x10 * (val)))
#define GPT_CLK_SRC(val)        (((val) & 0x1) << 4)
#define GPT_CLK_SRC_SYS13M      (0)
#define GPT_CLK_SRC_RTC32K      (1)
#define GPT_CLK_DIV1            (0x0)
#define GPT_CLK_DIV2            (0x1)

#define GPT_CNT_REG(val)        (0x08 + (0x10 * (val)))
#define GPT_CMP_REG(val)        (0x0C + (0x10 * (val)))

/* system timer */
#define SYST_BASE               (0x40)

#define SYST_CON                (SYST_BASE + 0x0)
#define SYST_VAL                (SYST_BASE + 0x4)

#define SYST_CON_REG(to)        (timer_of_base(to) + SYST_CON)
#define SYST_VAL_REG(to)        (timer_of_base(to) + SYST_VAL)

/*
 * SYST_CON_EN: Clock enable. Shall be set to
 *   - Start timer countdown.
 *   - Allow timeout ticks being updated.
 *   - Allow changing interrupt status,like clear irq pending.
 *
 * SYST_CON_IRQ_EN: Set to enable interrupt.
 *
 * SYST_CON_IRQ_CLR: Set to clear interrupt.
 */
#define SYST_CON_EN              BIT(0)
#define SYST_CON_IRQ_EN          BIT(1)
#define SYST_CON_IRQ_CLR         BIT(4)

static void __iomem *gpt_sched_reg __read_mostly;

static void mtk_syst_ack_irq(struct timer_of *to)
{
        /* Clear and disable interrupt */
        writel(SYST_CON_EN, SYST_CON_REG(to));
        writel(SYST_CON_IRQ_CLR | SYST_CON_EN, SYST_CON_REG(to));
}

static irqreturn_t mtk_syst_handler(int irq, void *dev_id)
{
        struct clock_event_device *clkevt = dev_id;
        struct timer_of *to = to_timer_of(clkevt);

        mtk_syst_ack_irq(to);
        clkevt->event_handler(clkevt);

        return IRQ_HANDLED;
}

static int mtk_syst_clkevt_next_event(unsigned long ticks,
                                      struct clock_event_device *clkevt)
{
        struct timer_of *to = to_timer_of(clkevt);

        /* Enable clock to allow timeout tick update later */
        writel(SYST_CON_EN, SYST_CON_REG(to));

        /*
         * Write new timeout ticks. Timer shall start countdown
         * after timeout ticks are updated.
         */
        writel(ticks, SYST_VAL_REG(to));

        /* Enable interrupt */
        writel(SYST_CON_EN | SYST_CON_IRQ_EN, SYST_CON_REG(to));

        return 0;
}

static int mtk_syst_clkevt_shutdown(struct clock_event_device *clkevt)
{
        /* Clear any irq */
        mtk_syst_ack_irq(to_timer_of(clkevt));

        /* Disable timer */
        writel(0, SYST_CON_REG(to_timer_of(clkevt)));

        return 0;
}

static int mtk_syst_clkevt_resume(struct clock_event_device *clkevt)
{
        return mtk_syst_clkevt_shutdown(clkevt);
}

static int mtk_syst_clkevt_oneshot(struct clock_event_device *clkevt)
{
        return 0;
}

static u64 notrace mtk_gpt_read_sched_clock(void)
{
        return readl_relaxed(gpt_sched_reg);
}

static void mtk_gpt_clkevt_time_stop(struct timer_of *to, u8 timer)
{
        u32 val;

        val = readl(timer_of_base(to) + GPT_CTRL_REG(timer));
        writel(val & ~GPT_CTRL_ENABLE, timer_of_base(to) +
               GPT_CTRL_REG(timer));
}

static void mtk_gpt_clkevt_time_setup(struct timer_of *to,
                                      unsigned long delay, u8 timer)
{
        writel(delay, timer_of_base(to) + GPT_CMP_REG(timer));
}

static void mtk_gpt_clkevt_time_start(struct timer_of *to,
                                      bool periodic, u8 timer)
{
        u32 val;

        /* Acknowledge interrupt */
        writel(GPT_IRQ_ACK(timer), timer_of_base(to) + GPT_IRQ_ACK_REG);

        val = readl(timer_of_base(to) + GPT_CTRL_REG(timer));

        /* Clear 2 bit timer operation mode field */
        val &= ~GPT_CTRL_OP(0x3);

        if (periodic)
                val |= GPT_CTRL_OP(GPT_CTRL_OP_REPEAT);
        else
                val |= GPT_CTRL_OP(GPT_CTRL_OP_ONESHOT);

        writel(val | GPT_CTRL_ENABLE | GPT_CTRL_CLEAR,
               timer_of_base(to) + GPT_CTRL_REG(timer));
}

static int mtk_gpt_clkevt_shutdown(struct clock_event_device *clk)
{
        mtk_gpt_clkevt_time_stop(to_timer_of(clk), TIMER_CLK_EVT);

        return 0;
}

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

        mtk_gpt_clkevt_time_stop(to, TIMER_CLK_EVT);
        mtk_gpt_clkevt_time_setup(to, to->of_clk.period, TIMER_CLK_EVT);
        mtk_gpt_clkevt_time_start(to, true, TIMER_CLK_EVT);

        return 0;
}

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

        mtk_gpt_clkevt_time_stop(to, TIMER_CLK_EVT);
        mtk_gpt_clkevt_time_setup(to, event, TIMER_CLK_EVT);
        mtk_gpt_clkevt_time_start(to, false, TIMER_CLK_EVT);

        return 0;
}

static irqreturn_t mtk_gpt_interrupt(int irq, void *dev_id)
{
        struct clock_event_device *clkevt = (struct clock_event_device *)dev_id;
        struct timer_of *to = to_timer_of(clkevt);

        /* Acknowledge timer0 irq */
        writel(GPT_IRQ_ACK(TIMER_CLK_EVT), timer_of_base(to) + GPT_IRQ_ACK_REG);
        clkevt->event_handler(clkevt);

        return IRQ_HANDLED;
}

static void
__init mtk_gpt_setup(struct timer_of *to, u8 timer, u8 option)
{
        writel(GPT_CTRL_CLEAR | GPT_CTRL_DISABLE,
               timer_of_base(to) + GPT_CTRL_REG(timer));

        writel(GPT_CLK_SRC(GPT_CLK_SRC_SYS13M) | GPT_CLK_DIV1,
               timer_of_base(to) + GPT_CLK_REG(timer));

        writel(0x0, timer_of_base(to) + GPT_CMP_REG(timer));

        writel(GPT_CTRL_OP(option) | GPT_CTRL_ENABLE,
               timer_of_base(to) + GPT_CTRL_REG(timer));
}

static void mtk_gpt_enable_irq(struct timer_of *to, u8 timer)
{
        u32 val;

        /* Disable all interrupts */
        writel(0x0, timer_of_base(to) + GPT_IRQ_EN_REG);

        /* Acknowledge all spurious pending interrupts */
        writel(0x3f, timer_of_base(to) + GPT_IRQ_ACK_REG);

        val = readl(timer_of_base(to) + GPT_IRQ_EN_REG);
        writel(val | GPT_IRQ_ENABLE(timer),
               timer_of_base(to) + GPT_IRQ_EN_REG);
}

static void mtk_gpt_resume(struct clock_event_device *clk)
{
        struct timer_of *to = to_timer_of(clk);

        mtk_gpt_enable_irq(to, TIMER_CLK_EVT);
}

static void mtk_gpt_suspend(struct clock_event_device *clk)
{
        struct timer_of *to = to_timer_of(clk);

        /* Disable all interrupts */
        writel(0x0, timer_of_base(to) + GPT_IRQ_EN_REG);

        /*
         * This is called with interrupts disabled,
         * so we need to ack any interrupt that is pending
         * or for example ATF will prevent a suspend from completing.
         */
        writel(0x3f, timer_of_base(to) + GPT_IRQ_ACK_REG);
}

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

        .clkevt = {
                .name = "mtk-clkevt",
                .rating = 300,
                .cpumask = cpu_possible_mask,
        },

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

static int __init mtk_syst_init(struct device_node *node)
{
        int ret;

        to.clkevt.features = CLOCK_EVT_FEAT_DYNIRQ | CLOCK_EVT_FEAT_ONESHOT;
        to.clkevt.set_state_shutdown = mtk_syst_clkevt_shutdown;
        to.clkevt.set_state_oneshot = mtk_syst_clkevt_oneshot;
        to.clkevt.tick_resume = mtk_syst_clkevt_resume;
        to.clkevt.set_next_event = mtk_syst_clkevt_next_event;
        to.of_irq.handler = mtk_syst_handler;

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

        clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
                                        TIMER_SYNC_TICKS, 0xffffffff);

        return 0;
}

static int __init mtk_gpt_init(struct device_node *node)
{
        int ret;

        to.clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
        to.clkevt.set_state_shutdown = mtk_gpt_clkevt_shutdown;
        to.clkevt.set_state_periodic = mtk_gpt_clkevt_set_periodic;
        to.clkevt.set_state_oneshot = mtk_gpt_clkevt_shutdown;
        to.clkevt.tick_resume = mtk_gpt_clkevt_shutdown;
        to.clkevt.set_next_event = mtk_gpt_clkevt_next_event;
        to.clkevt.suspend = mtk_gpt_suspend;
        to.clkevt.resume = mtk_gpt_resume;
        to.of_irq.handler = mtk_gpt_interrupt;

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

        /* Configure clock source */
        mtk_gpt_setup(&to, TIMER_CLK_SRC, GPT_CTRL_OP_FREERUN);
        clocksource_mmio_init(timer_of_base(&to) + GPT_CNT_REG(TIMER_CLK_SRC),
                              node->name, timer_of_rate(&to), 300, 32,
                              clocksource_mmio_readl_up);
        gpt_sched_reg = timer_of_base(&to) + GPT_CNT_REG(TIMER_CLK_SRC);
        sched_clock_register(mtk_gpt_read_sched_clock, 32, timer_of_rate(&to));

        /* Configure clock event */
        mtk_gpt_setup(&to, TIMER_CLK_EVT, GPT_CTRL_OP_REPEAT);
        clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
                                        TIMER_SYNC_TICKS, 0xffffffff);

        mtk_gpt_enable_irq(&to, TIMER_CLK_EVT);

        return 0;
}
TIMER_OF_DECLARE(mtk_mt6577, "mediatek,mt6577-timer", mtk_gpt_init);
TIMER_OF_DECLARE(mtk_mt6765, "mediatek,mt6765-timer", mtk_syst_init);