// SPDX-License-Identifier: GPL-2.0+
//
//  Copyright (C) 2000-2001 Deep Blue Solutions
//  Copyright (C) 2002 Shane Nay (shane@minirl.com)
//  Copyright (C) 2006-2007 Pavel Pisa (ppisa@pikron.com)
//  Copyright (C) 2008 Juergen Beisert (kernel@pengutronix.de)

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

/*
 * There are 4 versions of the timer hardware on Freescale MXC hardware.
 *  - MX1/MXL
 *  - MX21, MX27.
 *  - MX25, MX31, MX35, MX37, MX51, MX6Q(rev1.0)
 *  - MX6DL, MX6SX, MX6Q(rev1.1+)
 */
enum imx_gpt_type {
        GPT_TYPE_IMX1,          /* i.MX1 */
        GPT_TYPE_IMX21,         /* i.MX21/27 */
        GPT_TYPE_IMX31,         /* i.MX31/35/25/37/51/6Q */
        GPT_TYPE_IMX6DL,        /* i.MX6DL/SX/SL */
};

/* defines common for all i.MX */
#define MXC_TCTL                0x00
#define MXC_TCTL_TEN            (1 << 0) /* Enable module */
#define MXC_TPRER               0x04

/* MX1, MX21, MX27 */
#define MX1_2_TCTL_CLK_PCLK1    (1 << 1)
#define MX1_2_TCTL_IRQEN        (1 << 4)
#define MX1_2_TCTL_FRR          (1 << 8)
#define MX1_2_TCMP              0x08
#define MX1_2_TCN               0x10
#define MX1_2_TSTAT             0x14

/* MX21, MX27 */
#define MX2_TSTAT_CAPT          (1 << 1)
#define MX2_TSTAT_COMP          (1 << 0)

/* MX31, MX35, MX25, MX5, MX6 */
#define V2_TCTL_WAITEN          (1 << 3) /* Wait enable mode */
#define V2_TCTL_CLK_IPG         (1 << 6)
#define V2_TCTL_CLK_PER         (2 << 6)
#define V2_TCTL_CLK_OSC_DIV8    (5 << 6)
#define V2_TCTL_FRR             (1 << 9)
#define V2_TCTL_24MEN           (1 << 10)
#define V2_TPRER_PRE24M         12
#define V2_IR                   0x0c
#define V2_TSTAT                0x08
#define V2_TSTAT_OF1            (1 << 0)
#define V2_TCN                  0x24
#define V2_TCMP                 0x10

#define V2_TIMER_RATE_OSC_DIV8  3000000

struct imx_timer {
        enum imx_gpt_type type;
        void __iomem *base;
        int irq;
        struct clk *clk_per;
        struct clk *clk_ipg;
        const struct imx_gpt_data *gpt;
        struct clock_event_device ced;
};

struct imx_gpt_data {
        int reg_tstat;
        int reg_tcn;
        int reg_tcmp;
        void (*gpt_setup_tctl)(struct imx_timer *imxtm);
        void (*gpt_irq_enable)(struct imx_timer *imxtm);
        void (*gpt_irq_disable)(struct imx_timer *imxtm);
        void (*gpt_irq_acknowledge)(struct imx_timer *imxtm);
        int (*set_next_event)(unsigned long evt,
                              struct clock_event_device *ced);
};

static inline struct imx_timer *to_imx_timer(struct clock_event_device *ced)
{
        return container_of(ced, struct imx_timer, ced);
}

static void imx1_gpt_irq_disable(struct imx_timer *imxtm)
{
        unsigned int tmp;

        tmp = readl_relaxed(imxtm->base + MXC_TCTL);
        writel_relaxed(tmp & ~MX1_2_TCTL_IRQEN, imxtm->base + MXC_TCTL);
}

static void imx31_gpt_irq_disable(struct imx_timer *imxtm)
{
        writel_relaxed(0, imxtm->base + V2_IR);
}

static void imx1_gpt_irq_enable(struct imx_timer *imxtm)
{
        unsigned int tmp;

        tmp = readl_relaxed(imxtm->base + MXC_TCTL);
        writel_relaxed(tmp | MX1_2_TCTL_IRQEN, imxtm->base + MXC_TCTL);
}

static void imx31_gpt_irq_enable(struct imx_timer *imxtm)
{
        writel_relaxed(1<<0, imxtm->base + V2_IR);
}

static void imx1_gpt_irq_acknowledge(struct imx_timer *imxtm)
{
        writel_relaxed(0, imxtm->base + MX1_2_TSTAT);
}

static void imx21_gpt_irq_acknowledge(struct imx_timer *imxtm)
{
        writel_relaxed(MX2_TSTAT_CAPT | MX2_TSTAT_COMP,
                                imxtm->base + MX1_2_TSTAT);
}

static void imx31_gpt_irq_acknowledge(struct imx_timer *imxtm)
{
        writel_relaxed(V2_TSTAT_OF1, imxtm->base + V2_TSTAT);
}

static void __iomem *sched_clock_reg;

static u64 notrace mxc_read_sched_clock(void)
{
        return sched_clock_reg ? readl_relaxed(sched_clock_reg) : 0;
}

#if defined(CONFIG_ARM)
static struct delay_timer imx_delay_timer;

static unsigned long imx_read_current_timer(void)
{
        return readl_relaxed(sched_clock_reg);
}
#endif

static int __init mxc_clocksource_init(struct imx_timer *imxtm)
{
        unsigned int c = clk_get_rate(imxtm->clk_per);
        void __iomem *reg = imxtm->base + imxtm->gpt->reg_tcn;

#if defined(CONFIG_ARM)
        imx_delay_timer.read_current_timer = &imx_read_current_timer;
        imx_delay_timer.freq = c;
        register_current_timer_delay(&imx_delay_timer);
#endif

        sched_clock_reg = reg;

        sched_clock_register(mxc_read_sched_clock, 32, c);
        return clocksource_mmio_init(reg, "mxc_timer1", c, 200, 32,
                        clocksource_mmio_readl_up);
}

/* clock event */

static int mx1_2_set_next_event(unsigned long evt,
                              struct clock_event_device *ced)
{
        struct imx_timer *imxtm = to_imx_timer(ced);
        unsigned long tcmp;

        tcmp = readl_relaxed(imxtm->base + MX1_2_TCN) + evt;

        writel_relaxed(tcmp, imxtm->base + MX1_2_TCMP);

        return (int)(tcmp - readl_relaxed(imxtm->base + MX1_2_TCN)) < 0 ?
                                -ETIME : 0;
}

static int v2_set_next_event(unsigned long evt,
                              struct clock_event_device *ced)
{
        struct imx_timer *imxtm = to_imx_timer(ced);
        unsigned long tcmp;

        tcmp = readl_relaxed(imxtm->base + V2_TCN) + evt;

        writel_relaxed(tcmp, imxtm->base + V2_TCMP);

        return evt < 0x7fffffff &&
                (int)(tcmp - readl_relaxed(imxtm->base + V2_TCN)) < 0 ?
                                -ETIME : 0;
}

static int mxc_shutdown(struct clock_event_device *ced)
{
        struct imx_timer *imxtm = to_imx_timer(ced);
        u32 tcn;

        /* Disable interrupt in GPT module */
        imxtm->gpt->gpt_irq_disable(imxtm);

        tcn = readl_relaxed(imxtm->base + imxtm->gpt->reg_tcn);
        /* Set event time into far-far future */
        writel_relaxed(tcn - 3, imxtm->base + imxtm->gpt->reg_tcmp);

        /* Clear pending interrupt */
        imxtm->gpt->gpt_irq_acknowledge(imxtm);

#ifdef DEBUG
        printk(KERN_INFO "%s: changing mode\n", __func__);
#endif /* DEBUG */

        return 0;
}

static int mxc_set_oneshot(struct clock_event_device *ced)
{
        struct imx_timer *imxtm = to_imx_timer(ced);

        /* Disable interrupt in GPT module */
        imxtm->gpt->gpt_irq_disable(imxtm);

        if (!clockevent_state_oneshot(ced)) {
                u32 tcn = readl_relaxed(imxtm->base + imxtm->gpt->reg_tcn);
                /* Set event time into far-far future */
                writel_relaxed(tcn - 3, imxtm->base + imxtm->gpt->reg_tcmp);

                /* Clear pending interrupt */
                imxtm->gpt->gpt_irq_acknowledge(imxtm);
        }

#ifdef DEBUG
        printk(KERN_INFO "%s: changing mode\n", __func__);
#endif /* DEBUG */

        /*
         * Do not put overhead of interrupt enable/disable into
         * mxc_set_next_event(), the core has about 4 minutes
         * to call mxc_set_next_event() or shutdown clock after
         * mode switching
         */
        imxtm->gpt->gpt_irq_enable(imxtm);

        return 0;
}

/*
 * IRQ handler for the timer
 */
static irqreturn_t mxc_timer_interrupt(int irq, void *dev_id)
{
        struct clock_event_device *ced = dev_id;
        struct imx_timer *imxtm = to_imx_timer(ced);

        readl_relaxed(imxtm->base + imxtm->gpt->reg_tstat);

        imxtm->gpt->gpt_irq_acknowledge(imxtm);

        ced->event_handler(ced);

        return IRQ_HANDLED;
}

static int __init mxc_clockevent_init(struct imx_timer *imxtm)
{
        struct clock_event_device *ced = &imxtm->ced;

        ced->name = "mxc_timer1";
        ced->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_DYNIRQ;
        ced->set_state_shutdown = mxc_shutdown;
        ced->set_state_oneshot = mxc_set_oneshot;
        ced->tick_resume = mxc_shutdown;
        ced->set_next_event = imxtm->gpt->set_next_event;
        ced->rating = 200;
        ced->cpumask = cpumask_of(0);
        ced->irq = imxtm->irq;
        clockevents_config_and_register(ced, clk_get_rate(imxtm->clk_per),
                                        0xff, 0xfffffffe);

        return request_irq(imxtm->irq, mxc_timer_interrupt,
                           IRQF_TIMER | IRQF_IRQPOLL, "i.MX Timer Tick", ced);
}

static void imx1_gpt_setup_tctl(struct imx_timer *imxtm)
{
        u32 tctl_val;

        tctl_val = MX1_2_TCTL_FRR | MX1_2_TCTL_CLK_PCLK1 | MXC_TCTL_TEN;
        writel_relaxed(tctl_val, imxtm->base + MXC_TCTL);
}

static void imx31_gpt_setup_tctl(struct imx_timer *imxtm)
{
        u32 tctl_val;

        tctl_val = V2_TCTL_FRR | V2_TCTL_WAITEN | MXC_TCTL_TEN;
        if (clk_get_rate(imxtm->clk_per) == V2_TIMER_RATE_OSC_DIV8)
                tctl_val |= V2_TCTL_CLK_OSC_DIV8;
        else
                tctl_val |= V2_TCTL_CLK_PER;

        writel_relaxed(tctl_val, imxtm->base + MXC_TCTL);
}

static void imx6dl_gpt_setup_tctl(struct imx_timer *imxtm)
{
        u32 tctl_val;

        tctl_val = V2_TCTL_FRR | V2_TCTL_WAITEN | MXC_TCTL_TEN;
        if (clk_get_rate(imxtm->clk_per) == V2_TIMER_RATE_OSC_DIV8) {
                tctl_val |= V2_TCTL_CLK_OSC_DIV8;
                /* 24 / 8 = 3 MHz */
                writel_relaxed(7 << V2_TPRER_PRE24M, imxtm->base + MXC_TPRER);
                tctl_val |= V2_TCTL_24MEN;
        } else {
                tctl_val |= V2_TCTL_CLK_PER;
        }

        writel_relaxed(tctl_val, imxtm->base + MXC_TCTL);
}

static const struct imx_gpt_data imx1_gpt_data = {
        .reg_tstat = MX1_2_TSTAT,
        .reg_tcn = MX1_2_TCN,
        .reg_tcmp = MX1_2_TCMP,
        .gpt_irq_enable = imx1_gpt_irq_enable,
        .gpt_irq_disable = imx1_gpt_irq_disable,
        .gpt_irq_acknowledge = imx1_gpt_irq_acknowledge,
        .gpt_setup_tctl = imx1_gpt_setup_tctl,
        .set_next_event = mx1_2_set_next_event,
};

static const struct imx_gpt_data imx21_gpt_data = {
        .reg_tstat = MX1_2_TSTAT,
        .reg_tcn = MX1_2_TCN,
        .reg_tcmp = MX1_2_TCMP,
        .gpt_irq_enable = imx1_gpt_irq_enable,
        .gpt_irq_disable = imx1_gpt_irq_disable,
        .gpt_irq_acknowledge = imx21_gpt_irq_acknowledge,
        .gpt_setup_tctl = imx1_gpt_setup_tctl,
        .set_next_event = mx1_2_set_next_event,
};

static const struct imx_gpt_data imx31_gpt_data = {
        .reg_tstat = V2_TSTAT,
        .reg_tcn = V2_TCN,
        .reg_tcmp = V2_TCMP,
        .gpt_irq_enable = imx31_gpt_irq_enable,
        .gpt_irq_disable = imx31_gpt_irq_disable,
        .gpt_irq_acknowledge = imx31_gpt_irq_acknowledge,
        .gpt_setup_tctl = imx31_gpt_setup_tctl,
        .set_next_event = v2_set_next_event,
};

static const struct imx_gpt_data imx6dl_gpt_data = {
        .reg_tstat = V2_TSTAT,
        .reg_tcn = V2_TCN,
        .reg_tcmp = V2_TCMP,
        .gpt_irq_enable = imx31_gpt_irq_enable,
        .gpt_irq_disable = imx31_gpt_irq_disable,
        .gpt_irq_acknowledge = imx31_gpt_irq_acknowledge,
        .gpt_setup_tctl = imx6dl_gpt_setup_tctl,
        .set_next_event = v2_set_next_event,
};

static int __init _mxc_timer_init(struct imx_timer *imxtm)
{
        int ret;

        switch (imxtm->type) {
        case GPT_TYPE_IMX1:
                imxtm->gpt = &imx1_gpt_data;
                break;
        case GPT_TYPE_IMX21:
                imxtm->gpt = &imx21_gpt_data;
                break;
        case GPT_TYPE_IMX31:
                imxtm->gpt = &imx31_gpt_data;
                break;
        case GPT_TYPE_IMX6DL:
                imxtm->gpt = &imx6dl_gpt_data;
                break;
        default:
                return -EINVAL;
        }

        if (IS_ERR(imxtm->clk_per)) {
                pr_err("i.MX timer: unable to get clk\n");
                return PTR_ERR(imxtm->clk_per);
        }

        if (!IS_ERR(imxtm->clk_ipg))
                clk_prepare_enable(imxtm->clk_ipg);

        clk_prepare_enable(imxtm->clk_per);

        /*
         * Initialise to a known state (all timers off, and timing reset)
         */

        writel_relaxed(0, imxtm->base + MXC_TCTL);
        writel_relaxed(0, imxtm->base + MXC_TPRER); /* see datasheet note */

        imxtm->gpt->gpt_setup_tctl(imxtm);

        /* init and register the timer to the framework */
        ret = mxc_clocksource_init(imxtm);
        if (ret)
                return ret;

        return mxc_clockevent_init(imxtm);
}

static int __init mxc_timer_init_dt(struct device_node *np,  enum imx_gpt_type type)
{
        struct imx_timer *imxtm;
        static int initialized;
        int ret;

        /* Support one instance only */
        if (initialized)
                return 0;

        imxtm = kzalloc_obj(*imxtm);
        if (!imxtm)
                return -ENOMEM;

        imxtm->base = of_iomap(np, 0);
        if (!imxtm->base) {
                ret = -ENXIO;
                goto err_kfree;
        }

        imxtm->irq = irq_of_parse_and_map(np, 0);
        if (imxtm->irq <= 0) {
                ret = -EINVAL;
                goto err_kfree;
        }

        imxtm->clk_ipg = of_clk_get_by_name(np, "ipg");

        /* Try osc_per first, and fall back to per otherwise */
        imxtm->clk_per = of_clk_get_by_name(np, "osc_per");
        if (IS_ERR(imxtm->clk_per))
                imxtm->clk_per = of_clk_get_by_name(np, "per");

        imxtm->type = type;

        ret = _mxc_timer_init(imxtm);
        if (ret)
                goto err_kfree;

        initialized = 1;

        return 0;

err_kfree:
        kfree(imxtm);
        return ret;
}

static int __init imx1_timer_init_dt(struct device_node *np)
{
        return mxc_timer_init_dt(np, GPT_TYPE_IMX1);
}

static int __init imx21_timer_init_dt(struct device_node *np)
{
        return mxc_timer_init_dt(np, GPT_TYPE_IMX21);
}

static int __init imx31_timer_init_dt(struct device_node *np)
{
        enum imx_gpt_type type = GPT_TYPE_IMX31;

        /*
         * We were using the same compatible string for i.MX6Q/D and i.MX6DL/S
         * GPT device, while they actually have different programming model.
         * This is a workaround to keep the existing i.MX6DL/S DTBs continue
         * working with the new kernel.
         */
        if (of_machine_is_compatible("fsl,imx6dl"))
                type = GPT_TYPE_IMX6DL;

        return mxc_timer_init_dt(np, type);
}

static int __init imx6dl_timer_init_dt(struct device_node *np)
{
        return mxc_timer_init_dt(np, GPT_TYPE_IMX6DL);
}

TIMER_OF_DECLARE(imx1_timer, "fsl,imx1-gpt", imx1_timer_init_dt);
TIMER_OF_DECLARE(imx21_timer, "fsl,imx21-gpt", imx21_timer_init_dt);
TIMER_OF_DECLARE(imx27_timer, "fsl,imx27-gpt", imx21_timer_init_dt);
TIMER_OF_DECLARE(imx31_timer, "fsl,imx31-gpt", imx31_timer_init_dt);
TIMER_OF_DECLARE(imx25_timer, "fsl,imx25-gpt", imx31_timer_init_dt);
TIMER_OF_DECLARE(imx50_timer, "fsl,imx50-gpt", imx31_timer_init_dt);
TIMER_OF_DECLARE(imx51_timer, "fsl,imx51-gpt", imx31_timer_init_dt);
TIMER_OF_DECLARE(imx53_timer, "fsl,imx53-gpt", imx31_timer_init_dt);
TIMER_OF_DECLARE(imx6q_timer, "fsl,imx6q-gpt", imx31_timer_init_dt);
TIMER_OF_DECLARE(imx6dl_timer, "fsl,imx6dl-gpt", imx6dl_timer_init_dt);
TIMER_OF_DECLARE(imx6sl_timer, "fsl,imx6sl-gpt", imx6dl_timer_init_dt);
TIMER_OF_DECLARE(imx6sx_timer, "fsl,imx6sx-gpt", imx6dl_timer_init_dt);