// SPDX-License-Identifier: GPL-2.0
/*
 * Clocksource driver for NXP LPC32xx/18xx/43xx timer
 *
 * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
 *
 * Based on:
 * time-efm32 Copyright (C) 2013 Pengutronix
 * mach-lpc32xx/timer.c Copyright (C) 2009 - 2010 NXP Semiconductors
 */

#define pr_fmt(fmt) "%s: " fmt, __func__

#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/sched_clock.h>

#define LPC32XX_TIMER_IR                0x000
#define  LPC32XX_TIMER_IR_MR0INT        BIT(0)
#define LPC32XX_TIMER_TCR               0x004
#define  LPC32XX_TIMER_TCR_CEN          BIT(0)
#define  LPC32XX_TIMER_TCR_CRST         BIT(1)
#define LPC32XX_TIMER_TC                0x008
#define LPC32XX_TIMER_PR                0x00c
#define LPC32XX_TIMER_MCR               0x014
#define  LPC32XX_TIMER_MCR_MR0I         BIT(0)
#define  LPC32XX_TIMER_MCR_MR0R         BIT(1)
#define  LPC32XX_TIMER_MCR_MR0S         BIT(2)
#define LPC32XX_TIMER_MR0               0x018
#define LPC32XX_TIMER_CTCR              0x070

struct lpc32xx_clock_event_ddata {
        struct clock_event_device evtdev;
        void __iomem *base;
        u32 ticks_per_jiffy;
};

/* Needed for the sched clock */
static void __iomem *clocksource_timer_counter;

static u64 notrace lpc32xx_read_sched_clock(void)
{
        return readl(clocksource_timer_counter);
}

static unsigned long lpc32xx_delay_timer_read(void)
{
        return readl(clocksource_timer_counter);
}

static struct delay_timer lpc32xx_delay_timer = {
        .read_current_timer = lpc32xx_delay_timer_read,
};

static int lpc32xx_clkevt_next_event(unsigned long delta,
                                     struct clock_event_device *evtdev)
{
        struct lpc32xx_clock_event_ddata *ddata =
                container_of(evtdev, struct lpc32xx_clock_event_ddata, evtdev);

        /*
         * Place timer in reset and program the delta in the match
         * channel 0 (MR0). When the timer counter matches the value
         * in MR0 register the match will trigger an interrupt.
         * After setup the timer is released from reset and enabled.
         */
        writel_relaxed(LPC32XX_TIMER_TCR_CRST, ddata->base + LPC32XX_TIMER_TCR);
        writel_relaxed(delta, ddata->base + LPC32XX_TIMER_MR0);
        writel_relaxed(LPC32XX_TIMER_TCR_CEN, ddata->base + LPC32XX_TIMER_TCR);

        return 0;
}

static int lpc32xx_clkevt_shutdown(struct clock_event_device *evtdev)
{
        struct lpc32xx_clock_event_ddata *ddata =
                container_of(evtdev, struct lpc32xx_clock_event_ddata, evtdev);

        /* Disable the timer */
        writel_relaxed(0, ddata->base + LPC32XX_TIMER_TCR);

        return 0;
}

static int lpc32xx_clkevt_oneshot(struct clock_event_device *evtdev)
{
        struct lpc32xx_clock_event_ddata *ddata =
                container_of(evtdev, struct lpc32xx_clock_event_ddata, evtdev);

        /*
         * When using oneshot, we must also disable the timer
         * to wait for the first call to set_next_event().
         */
        writel_relaxed(0, ddata->base + LPC32XX_TIMER_TCR);

        /* Enable interrupt, reset on match and stop on match (MCR). */
        writel_relaxed(LPC32XX_TIMER_MCR_MR0I | LPC32XX_TIMER_MCR_MR0R |
                       LPC32XX_TIMER_MCR_MR0S, ddata->base + LPC32XX_TIMER_MCR);
        return 0;
}

static int lpc32xx_clkevt_periodic(struct clock_event_device *evtdev)
{
        struct lpc32xx_clock_event_ddata *ddata =
                container_of(evtdev, struct lpc32xx_clock_event_ddata, evtdev);

        /* Enable interrupt and reset on match. */
        writel_relaxed(LPC32XX_TIMER_MCR_MR0I | LPC32XX_TIMER_MCR_MR0R,
                       ddata->base + LPC32XX_TIMER_MCR);

        /*
         * Place timer in reset and program the delta in the match
         * channel 0 (MR0).
         */
        writel_relaxed(LPC32XX_TIMER_TCR_CRST, ddata->base + LPC32XX_TIMER_TCR);
        writel_relaxed(ddata->ticks_per_jiffy, ddata->base + LPC32XX_TIMER_MR0);
        writel_relaxed(LPC32XX_TIMER_TCR_CEN, ddata->base + LPC32XX_TIMER_TCR);

        return 0;
}

static irqreturn_t lpc32xx_clock_event_handler(int irq, void *dev_id)
{
        struct lpc32xx_clock_event_ddata *ddata = dev_id;

        /* Clear match on channel 0 */
        writel_relaxed(LPC32XX_TIMER_IR_MR0INT, ddata->base + LPC32XX_TIMER_IR);

        ddata->evtdev.event_handler(&ddata->evtdev);

        return IRQ_HANDLED;
}

static struct lpc32xx_clock_event_ddata lpc32xx_clk_event_ddata = {
        .evtdev = {
                .name                   = "lpc3220 clockevent",
                .features               = CLOCK_EVT_FEAT_ONESHOT |
                                          CLOCK_EVT_FEAT_PERIODIC,
                .rating                 = 300,
                .set_next_event         = lpc32xx_clkevt_next_event,
                .set_state_shutdown     = lpc32xx_clkevt_shutdown,
                .set_state_oneshot      = lpc32xx_clkevt_oneshot,
                .set_state_periodic     = lpc32xx_clkevt_periodic,
        },
};

static int __init lpc32xx_clocksource_init(struct device_node *np)
{
        void __iomem *base;
        unsigned long rate;
        struct clk *clk;
        int ret;

        clk = of_clk_get_by_name(np, "timerclk");
        if (IS_ERR(clk)) {
                pr_err("clock get failed (%ld)\n", PTR_ERR(clk));
                return PTR_ERR(clk);
        }

        ret = clk_prepare_enable(clk);
        if (ret) {
                pr_err("clock enable failed (%d)\n", ret);
                goto err_clk_enable;
        }

        base = of_iomap(np, 0);
        if (!base) {
                pr_err("unable to map registers\n");
                ret = -EADDRNOTAVAIL;
                goto err_iomap;
        }

        /*
         * Disable and reset timer then set it to free running timer
         * mode (CTCR) with no prescaler (PR) or match operations (MCR).
         * After setup the timer is released from reset and enabled.
         */
        writel_relaxed(LPC32XX_TIMER_TCR_CRST, base + LPC32XX_TIMER_TCR);
        writel_relaxed(0, base + LPC32XX_TIMER_PR);
        writel_relaxed(0, base + LPC32XX_TIMER_MCR);
        writel_relaxed(0, base + LPC32XX_TIMER_CTCR);
        writel_relaxed(LPC32XX_TIMER_TCR_CEN, base + LPC32XX_TIMER_TCR);

        rate = clk_get_rate(clk);
        ret = clocksource_mmio_init(base + LPC32XX_TIMER_TC, "lpc3220 timer",
                                    rate, 300, 32, clocksource_mmio_readl_up);
        if (ret) {
                pr_err("failed to init clocksource (%d)\n", ret);
                goto err_clocksource_init;
        }

        clocksource_timer_counter = base + LPC32XX_TIMER_TC;
        lpc32xx_delay_timer.freq = rate;
        register_current_timer_delay(&lpc32xx_delay_timer);
        sched_clock_register(lpc32xx_read_sched_clock, 32, rate);

        return 0;

err_clocksource_init:
        iounmap(base);
err_iomap:
        clk_disable_unprepare(clk);
err_clk_enable:
        clk_put(clk);
        return ret;
}

static int __init lpc32xx_clockevent_init(struct device_node *np)
{
        void __iomem *base;
        unsigned long rate;
        struct clk *clk;
        int ret, irq;

        clk = of_clk_get_by_name(np, "timerclk");
        if (IS_ERR(clk)) {
                pr_err("clock get failed (%ld)\n", PTR_ERR(clk));
                return PTR_ERR(clk);
        }

        ret = clk_prepare_enable(clk);
        if (ret) {
                pr_err("clock enable failed (%d)\n", ret);
                goto err_clk_enable;
        }

        base = of_iomap(np, 0);
        if (!base) {
                pr_err("unable to map registers\n");
                ret = -EADDRNOTAVAIL;
                goto err_iomap;
        }

        irq = irq_of_parse_and_map(np, 0);
        if (!irq) {
                pr_err("get irq failed\n");
                ret = -ENOENT;
                goto err_irq;
        }

        /*
         * Disable timer and clear any pending interrupt (IR) on match
         * channel 0 (MR0). Clear the prescaler as it's not used.
         */
        writel_relaxed(0, base + LPC32XX_TIMER_TCR);
        writel_relaxed(0, base + LPC32XX_TIMER_PR);
        writel_relaxed(0, base + LPC32XX_TIMER_CTCR);
        writel_relaxed(LPC32XX_TIMER_IR_MR0INT, base + LPC32XX_TIMER_IR);

        rate = clk_get_rate(clk);
        lpc32xx_clk_event_ddata.base = base;
        lpc32xx_clk_event_ddata.ticks_per_jiffy = DIV_ROUND_CLOSEST(rate, HZ);
        clockevents_config_and_register(&lpc32xx_clk_event_ddata.evtdev,
                                        rate, 1, -1);

        ret = request_irq(irq, lpc32xx_clock_event_handler,
                          IRQF_TIMER | IRQF_IRQPOLL, "lpc3220 clockevent",
                          &lpc32xx_clk_event_ddata);
        if (ret) {
                pr_err("request irq failed\n");
                goto err_irq;
        }

        return 0;

err_irq:
        iounmap(base);
err_iomap:
        clk_disable_unprepare(clk);
err_clk_enable:
        clk_put(clk);
        return ret;
}

/*
 * This function asserts that we have exactly one clocksource and one
 * clock_event_device in the end.
 */
static int __init lpc32xx_timer_init(struct device_node *np)
{
        static int has_clocksource, has_clockevent;
        int ret = 0;

        if (!has_clocksource) {
                ret = lpc32xx_clocksource_init(np);
                if (!ret) {
                        has_clocksource = 1;
                        return 0;
                }
        }

        if (!has_clockevent) {
                ret = lpc32xx_clockevent_init(np);
                if (!ret) {
                        has_clockevent = 1;
                        return 0;
                }
        }

        return ret;
}
TIMER_OF_DECLARE(lpc32xx_timer, "nxp,lpc3220-timer", lpc32xx_timer_init);