// SPDX-License-Identifier: GPL-2.0+
/*
 * Watchdog device driver for DA9062 and DA9061 PMICs
 * Copyright (C) 2015  Dialog Semiconductor Ltd.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/watchdog.h>
#include <linux/platform_device.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/mfd/da9062/registers.h>
#include <linux/mfd/da9062/core.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/of.h>

static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 };
#define DA9062_TWDSCALE_DISABLE         0
#define DA9062_TWDSCALE_MIN             1
#define DA9062_TWDSCALE_MAX             (ARRAY_SIZE(wdt_timeout) - 1)
#define DA9062_WDT_MIN_TIMEOUT          wdt_timeout[DA9062_TWDSCALE_MIN]
#define DA9062_WDT_MAX_TIMEOUT          wdt_timeout[DA9062_TWDSCALE_MAX]
#define DA9062_WDG_DEFAULT_TIMEOUT      wdt_timeout[DA9062_TWDSCALE_MAX-1]
#define DA9062_RESET_PROTECTION_MS      300

struct da9062_watchdog {
        struct da9062 *hw;
        struct watchdog_device wdtdev;
        bool use_sw_pm;
};

static unsigned int da9062_wdt_read_timeout(struct da9062_watchdog *wdt)
{
        unsigned int val;

        regmap_read(wdt->hw->regmap, DA9062AA_CONTROL_D, &val);

        return wdt_timeout[val & DA9062AA_TWDSCALE_MASK];
}

static unsigned int da9062_wdt_timeout_to_sel(unsigned int secs)
{
        unsigned int i;

        for (i = DA9062_TWDSCALE_MIN; i <= DA9062_TWDSCALE_MAX; i++) {
                if (wdt_timeout[i] >= secs)
                        return i;
        }

        return DA9062_TWDSCALE_MAX;
}

static int da9062_reset_watchdog_timer(struct da9062_watchdog *wdt)
{
        return regmap_update_bits(wdt->hw->regmap, DA9062AA_CONTROL_F,
                                  DA9062AA_WATCHDOG_MASK,
                                  DA9062AA_WATCHDOG_MASK);
}

static int da9062_wdt_update_timeout_register(struct da9062_watchdog *wdt,
                                              unsigned int regval)
{
        struct da9062 *chip = wdt->hw;

        regmap_update_bits(chip->regmap,
                                  DA9062AA_CONTROL_D,
                                  DA9062AA_TWDSCALE_MASK,
                                  DA9062_TWDSCALE_DISABLE);

        usleep_range(150, 300);

        return regmap_update_bits(chip->regmap,
                                  DA9062AA_CONTROL_D,
                                  DA9062AA_TWDSCALE_MASK,
                                  regval);
}

static int da9062_wdt_start(struct watchdog_device *wdd)
{
        struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
        unsigned int selector;
        int ret;

        selector = da9062_wdt_timeout_to_sel(wdt->wdtdev.timeout);
        ret = da9062_wdt_update_timeout_register(wdt, selector);
        if (ret)
                dev_err(wdt->hw->dev, "Watchdog failed to start (err = %d)\n",
                        ret);

        return ret;
}

static int da9062_wdt_stop(struct watchdog_device *wdd)
{
        struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
        int ret;

        ret = regmap_update_bits(wdt->hw->regmap,
                                 DA9062AA_CONTROL_D,
                                 DA9062AA_TWDSCALE_MASK,
                                 DA9062_TWDSCALE_DISABLE);
        if (ret)
                dev_err(wdt->hw->dev, "Watchdog failed to stop (err = %d)\n",
                        ret);

        return ret;
}

static int da9062_wdt_ping(struct watchdog_device *wdd)
{
        struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
        int ret;

        /*
         * Prevent pings from occurring late in system poweroff/reboot sequence
         * and possibly locking out restart handler from accessing i2c bus.
         */
        if (system_state > SYSTEM_RUNNING)
                return 0;

        ret = da9062_reset_watchdog_timer(wdt);
        if (ret)
                dev_err(wdt->hw->dev, "Failed to ping the watchdog (err = %d)\n",
                        ret);

        return ret;
}

static int da9062_wdt_set_timeout(struct watchdog_device *wdd,
                                  unsigned int timeout)
{
        struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
        unsigned int selector;
        int ret;

        selector = da9062_wdt_timeout_to_sel(timeout);
        ret = da9062_wdt_update_timeout_register(wdt, selector);
        if (ret)
                dev_err(wdt->hw->dev, "Failed to set watchdog timeout (err = %d)\n",
                        ret);
        else
                wdd->timeout = wdt_timeout[selector];

        return ret;
}

static int da9062_wdt_restart(struct watchdog_device *wdd, unsigned long action,
                              void *data)
{
        struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
        struct i2c_client *client = to_i2c_client(wdt->hw->dev);
        union i2c_smbus_data msg;
        int ret;

        /*
         * Don't use regmap because it is not atomic safe. Additionally, use
         * unlocked flavor of i2c_smbus_xfer to avoid scenario where i2c bus
         * might be previously locked by some process unable to release the
         * lock due to interrupts already being disabled at this late stage.
         */
        msg.byte = DA9062AA_SHUTDOWN_MASK;
        ret = __i2c_smbus_xfer(client->adapter, client->addr, client->flags,
                               I2C_SMBUS_WRITE, DA9062AA_CONTROL_F,
                               I2C_SMBUS_BYTE_DATA, &msg);

        if (ret < 0)
                dev_alert(wdt->hw->dev, "Failed to shutdown (err = %d)\n",
                          ret);

        /* wait for reset to assert... */
        mdelay(500);

        return ret;
}

static const struct watchdog_info da9062_watchdog_info = {
        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
        .identity = "DA9062 WDT",
};

static const struct watchdog_ops da9062_watchdog_ops = {
        .owner = THIS_MODULE,
        .start = da9062_wdt_start,
        .stop = da9062_wdt_stop,
        .ping = da9062_wdt_ping,
        .set_timeout = da9062_wdt_set_timeout,
        .restart = da9062_wdt_restart,
};

static const struct of_device_id da9062_compatible_id_table[] = {
        { .compatible = "dlg,da9062-watchdog", },
        { },
};

MODULE_DEVICE_TABLE(of, da9062_compatible_id_table);

static int da9062_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        unsigned int timeout;
        struct da9062 *chip;
        struct da9062_watchdog *wdt;

        chip = dev_get_drvdata(dev->parent);
        if (!chip)
                return -EINVAL;

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

        wdt->use_sw_pm = device_property_present(dev, "dlg,use-sw-pm");

        wdt->hw = chip;

        wdt->wdtdev.info = &da9062_watchdog_info;
        wdt->wdtdev.ops = &da9062_watchdog_ops;
        wdt->wdtdev.min_timeout = DA9062_WDT_MIN_TIMEOUT;
        wdt->wdtdev.max_timeout = DA9062_WDT_MAX_TIMEOUT;
        wdt->wdtdev.min_hw_heartbeat_ms = DA9062_RESET_PROTECTION_MS;
        wdt->wdtdev.timeout = DA9062_WDG_DEFAULT_TIMEOUT;
        wdt->wdtdev.status = WATCHDOG_NOWAYOUT_INIT_STATUS;
        wdt->wdtdev.parent = dev;

        watchdog_set_restart_priority(&wdt->wdtdev, 128);

        watchdog_set_drvdata(&wdt->wdtdev, wdt);
        dev_set_drvdata(dev, &wdt->wdtdev);

        timeout = da9062_wdt_read_timeout(wdt);
        if (timeout)
                wdt->wdtdev.timeout = timeout;

        /* Set timeout from DT value if available */
        watchdog_init_timeout(&wdt->wdtdev, 0, dev);

        if (timeout) {
                da9062_wdt_set_timeout(&wdt->wdtdev, wdt->wdtdev.timeout);
                set_bit(WDOG_HW_RUNNING, &wdt->wdtdev.status);
        }

        return devm_watchdog_register_device(dev, &wdt->wdtdev);
}

static int __maybe_unused da9062_wdt_suspend(struct device *dev)
{
        struct watchdog_device *wdd = dev_get_drvdata(dev);
        struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);

        if (!wdt->use_sw_pm)
                return 0;

        if (watchdog_active(wdd))
                return da9062_wdt_stop(wdd);

        return 0;
}

static int __maybe_unused da9062_wdt_resume(struct device *dev)
{
        struct watchdog_device *wdd = dev_get_drvdata(dev);
        struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);

        if (!wdt->use_sw_pm)
                return 0;

        if (watchdog_active(wdd))
                return da9062_wdt_start(wdd);

        return 0;
}

static SIMPLE_DEV_PM_OPS(da9062_wdt_pm_ops,
                         da9062_wdt_suspend, da9062_wdt_resume);

static struct platform_driver da9062_wdt_driver = {
        .probe = da9062_wdt_probe,
        .driver = {
                .name = "da9062-watchdog",
                .pm = &da9062_wdt_pm_ops,
                .of_match_table = da9062_compatible_id_table,
        },
};
module_platform_driver(da9062_wdt_driver);

MODULE_AUTHOR("S Twiss <stwiss.opensource@diasemi.com>");
MODULE_DESCRIPTION("WDT device driver for Dialog DA9062 and DA9061");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:da9062-watchdog");