// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright 2018-2019 NXP.
 */

#include <linux/arm-smccc.h>
#include <linux/firmware/imx/sci.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>

#define DEFAULT_TIMEOUT 60
/*
 * Software timer tick implemented in scfw side, support 10ms to 0xffffffff ms
 * in theory, but for normal case, 1s~128s is enough, you can change this max
 * value in case it's not enough.
 */
#define MAX_TIMEOUT 128

#define IMX_SIP_TIMER                   0xC2000002
#define IMX_SIP_TIMER_START_WDOG                0x01
#define IMX_SIP_TIMER_STOP_WDOG         0x02
#define IMX_SIP_TIMER_SET_WDOG_ACT      0x03
#define IMX_SIP_TIMER_PING_WDOG         0x04
#define IMX_SIP_TIMER_SET_TIMEOUT_WDOG  0x05
#define IMX_SIP_TIMER_GET_WDOG_STAT     0x06
#define IMX_SIP_TIMER_SET_PRETIME_WDOG  0x07

#define SC_TIMER_WDOG_ACTION_PARTITION  0

#define SC_IRQ_WDOG                     1
#define SC_IRQ_GROUP_WDOG               1
#define SC_TIMER_ERR_BUSY               10

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0000);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

struct imx_sc_wdt_device {
        struct watchdog_device wdd;
        struct notifier_block wdt_notifier;
};

static int imx_sc_wdt_ping(struct watchdog_device *wdog)
{
        struct arm_smccc_res res;

        arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_PING_WDOG,
                      0, 0, 0, 0, 0, 0, &res);

        return 0;
}

static bool imx_sc_wdt_is_running(void)
{
        struct arm_smccc_res res;

        arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_START_WDOG,
                      0, 0, 0, 0, 0, 0, &res);

        /* Already enabled (SC_TIMER_ERR_BUSY)? */
        if (res.a0 == SC_TIMER_ERR_BUSY)
                return true;

        /* Undo only if that was us who has (successfully) enabled the WDT */
        if (!res.a0)
                arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_STOP_WDOG,
                              0, 0, 0, 0, 0, 0, &res);

        return false;
}

static int imx_sc_wdt_start(struct watchdog_device *wdog)
{
        struct arm_smccc_res res;

        arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_START_WDOG,
                      0, 0, 0, 0, 0, 0, &res);

        /* Ignore if already enabled(SC_TIMER_ERR_BUSY) */
        if (res.a0 && res.a0 != SC_TIMER_ERR_BUSY)
                return -EACCES;

        arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_SET_WDOG_ACT,
                      SC_TIMER_WDOG_ACTION_PARTITION,
                      0, 0, 0, 0, 0, &res);
        return res.a0 ? -EACCES : 0;
}

static int imx_sc_wdt_stop(struct watchdog_device *wdog)
{
        struct arm_smccc_res res;

        arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_STOP_WDOG,
                      0, 0, 0, 0, 0, 0, &res);

        return res.a0 ? -EACCES : 0;
}

static int imx_sc_wdt_set_timeout(struct watchdog_device *wdog,
                                unsigned int timeout)
{
        struct arm_smccc_res res;

        wdog->timeout = timeout;
        arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_SET_TIMEOUT_WDOG,
                      timeout * 1000, 0, 0, 0, 0, 0, &res);

        return res.a0 ? -EACCES : 0;
}

static int imx_sc_wdt_set_pretimeout(struct watchdog_device *wdog,
                                     unsigned int pretimeout)
{
        struct arm_smccc_res res;

        /*
         * SCU firmware calculates pretimeout based on current time
         * stamp instead of watchdog timeout stamp, need to convert
         * the pretimeout to SCU firmware's timeout value.
         */
        arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_SET_PRETIME_WDOG,
                      (wdog->timeout - pretimeout) * 1000, 0, 0, 0,
                      0, 0, &res);
        if (res.a0)
                return -EACCES;

        wdog->pretimeout = pretimeout;

        return 0;
}

static int imx_sc_wdt_notify(struct notifier_block *nb,
                             unsigned long event, void *group)
{
        struct imx_sc_wdt_device *imx_sc_wdd =
                                 container_of(nb,
                                              struct imx_sc_wdt_device,
                                              wdt_notifier);

        if (event & SC_IRQ_WDOG &&
            *(u8 *)group == SC_IRQ_GROUP_WDOG)
                watchdog_notify_pretimeout(&imx_sc_wdd->wdd);

        return 0;
}

static void imx_sc_wdt_action(void *data)
{
        struct notifier_block *wdt_notifier = data;

        imx_scu_irq_unregister_notifier(wdt_notifier);
        imx_scu_irq_group_enable(SC_IRQ_GROUP_WDOG,
                                 SC_IRQ_WDOG,
                                 false);
}

static const struct watchdog_ops imx_sc_wdt_ops = {
        .owner = THIS_MODULE,
        .start = imx_sc_wdt_start,
        .stop  = imx_sc_wdt_stop,
        .ping  = imx_sc_wdt_ping,
        .set_timeout = imx_sc_wdt_set_timeout,
        .set_pretimeout = imx_sc_wdt_set_pretimeout,
};

static struct watchdog_info imx_sc_wdt_info = {
        .identity       = "i.MX SC watchdog timer",
        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
                          WDIOF_MAGICCLOSE,
};

static int imx_sc_wdt_probe(struct platform_device *pdev)
{
        struct imx_sc_wdt_device *imx_sc_wdd;
        struct watchdog_device *wdog;
        struct device *dev = &pdev->dev;
        int ret;

        imx_sc_wdd = devm_kzalloc(dev, sizeof(*imx_sc_wdd), GFP_KERNEL);
        if (!imx_sc_wdd)
                return -ENOMEM;

        platform_set_drvdata(pdev, imx_sc_wdd);

        wdog = &imx_sc_wdd->wdd;
        wdog->info = &imx_sc_wdt_info;
        wdog->ops = &imx_sc_wdt_ops;
        wdog->min_timeout = 1;
        wdog->max_timeout = MAX_TIMEOUT;
        wdog->parent = dev;
        wdog->timeout = DEFAULT_TIMEOUT;

        watchdog_init_timeout(wdog, 0, dev);

        ret = imx_sc_wdt_set_timeout(wdog, wdog->timeout);
        if (ret)
                return ret;

        if (imx_sc_wdt_is_running())
                set_bit(WDOG_HW_RUNNING, &wdog->status);

        watchdog_stop_on_reboot(wdog);
        watchdog_stop_on_unregister(wdog);

        ret = imx_scu_irq_group_enable(SC_IRQ_GROUP_WDOG,
                                       SC_IRQ_WDOG,
                                       true);
        if (ret) {
                dev_warn(dev, "Enable irq failed, pretimeout NOT supported\n");
                goto register_device;
        }

        imx_sc_wdd->wdt_notifier.notifier_call = imx_sc_wdt_notify;
        ret = imx_scu_irq_register_notifier(&imx_sc_wdd->wdt_notifier);
        if (ret) {
                imx_scu_irq_group_enable(SC_IRQ_GROUP_WDOG,
                                         SC_IRQ_WDOG,
                                         false);
                dev_warn(dev,
                         "Register irq notifier failed, pretimeout NOT supported\n");
                goto register_device;
        }

        ret = devm_add_action_or_reset(dev, imx_sc_wdt_action,
                                       &imx_sc_wdd->wdt_notifier);
        if (!ret)
                imx_sc_wdt_info.options |= WDIOF_PRETIMEOUT;
        else
                dev_warn(dev, "Add action failed, pretimeout NOT supported\n");

register_device:
        return devm_watchdog_register_device(dev, wdog);
}

static const struct of_device_id imx_sc_wdt_dt_ids[] = {
        { .compatible = "fsl,imx-sc-wdt", },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, imx_sc_wdt_dt_ids);

static struct platform_driver imx_sc_wdt_driver = {
        .probe          = imx_sc_wdt_probe,
        .driver         = {
                .name   = "imx-sc-wdt",
                .of_match_table = imx_sc_wdt_dt_ids,
        },
};
module_platform_driver(imx_sc_wdt_driver);

MODULE_AUTHOR("Robin Gong <yibin.gong@nxp.com>");
MODULE_DESCRIPTION("NXP i.MX system controller watchdog driver");
MODULE_LICENSE("GPL v2");