// SPDX-License-Identifier: GPL-2.0+
/*
 * Watchdog driver for DA9063 PMICs.
 *
 * Copyright(c) 2012 Dialog Semiconductor Ltd.
 *
 * Author: Mariusz Wojtasik <mariusz.wojtasik@diasemi.com>
 *
 */

#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/mfd/da9063/registers.h>
#include <linux/mfd/da9063/core.h>
#include <linux/property.h>
#include <linux/regmap.h>

/*
 * Watchdog selector to timeout in seconds.
 *   0: WDT disabled;
 *   others: timeout = 2048 ms * 2^(TWDSCALE-1).
 */
static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 };

#define DA9063_TWDSCALE_DISABLE         0
#define DA9063_TWDSCALE_MIN             1
#define DA9063_TWDSCALE_MAX             (ARRAY_SIZE(wdt_timeout) - 1)
#define DA9063_WDT_MIN_TIMEOUT          wdt_timeout[DA9063_TWDSCALE_MIN]
#define DA9063_WDT_MAX_TIMEOUT          wdt_timeout[DA9063_TWDSCALE_MAX]
#define DA9063_WDG_TIMEOUT              wdt_timeout[3]
#define DA9063_RESET_PROTECTION_MS      256

static unsigned int da9063_wdt_timeout_to_sel(unsigned int secs)
{
        unsigned int i;

        for (i = DA9063_TWDSCALE_MIN; i <= DA9063_TWDSCALE_MAX; i++) {
                if (wdt_timeout[i] >= secs)
                        return i;
        }

        return DA9063_TWDSCALE_MAX;
}

/*
 * Read the currently active timeout.
 * Zero means the watchdog is disabled.
 */
static unsigned int da9063_wdt_read_timeout(struct da9063 *da9063)
{
        unsigned int val;

        regmap_read(da9063->regmap, DA9063_REG_CONTROL_D, &val);

        return wdt_timeout[val & DA9063_TWDSCALE_MASK];
}

static int da9063_wdt_disable_timer(struct da9063 *da9063)
{
        return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
                                  DA9063_TWDSCALE_MASK,
                                  DA9063_TWDSCALE_DISABLE);
}

static int
da9063_wdt_update_timeout(struct da9063 *da9063, unsigned int timeout)
{
        unsigned int regval;
        int ret;

        /*
         * The watchdog triggers a reboot if a timeout value is already
         * programmed because the timeout value combines two functions
         * in one: indicating the counter limit and starting the watchdog.
         * The watchdog must be disabled to be able to change the timeout
         * value if the watchdog is already running. Then we can set the
         * new timeout value which enables the watchdog again.
         */
        ret = da9063_wdt_disable_timer(da9063);
        if (ret)
                return ret;

        usleep_range(150, 300);
        regval = da9063_wdt_timeout_to_sel(timeout);

        return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
                                  DA9063_TWDSCALE_MASK, regval);
}

static int da9063_wdt_start(struct watchdog_device *wdd)
{
        struct da9063 *da9063 = watchdog_get_drvdata(wdd);
        int ret;

        ret = da9063_wdt_update_timeout(da9063, wdd->timeout);
        if (ret)
                dev_err(da9063->dev, "Watchdog failed to start (err = %d)\n",
                        ret);

        return ret;
}

static int da9063_wdt_stop(struct watchdog_device *wdd)
{
        struct da9063 *da9063 = watchdog_get_drvdata(wdd);
        int ret;

        ret = da9063_wdt_disable_timer(da9063);
        if (ret)
                dev_alert(da9063->dev, "Watchdog failed to stop (err = %d)\n",
                          ret);

        return ret;
}

static int da9063_wdt_ping(struct watchdog_device *wdd)
{
        struct da9063 *da9063 = 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 = regmap_write(da9063->regmap, DA9063_REG_CONTROL_F,
                           DA9063_WATCHDOG);
        if (ret)
                dev_alert(da9063->dev, "Failed to ping the watchdog (err = %d)\n",
                          ret);

        return ret;
}

static int da9063_wdt_set_timeout(struct watchdog_device *wdd,
                                  unsigned int timeout)
{
        struct da9063 *da9063 = watchdog_get_drvdata(wdd);
        int ret = 0;

        /*
         * There are two cases when a set_timeout() will be called:
         * 1. The watchdog is off and someone wants to set the timeout for the
         *    further use.
         * 2. The watchdog is already running and a new timeout value should be
         *    set.
         *
         * The watchdog can't store a timeout value not equal zero without
         * enabling the watchdog, so the timeout must be buffered by the driver.
         */
        if (watchdog_active(wdd))
                ret = da9063_wdt_update_timeout(da9063, timeout);

        if (ret)
                dev_err(da9063->dev, "Failed to set watchdog timeout (err = %d)\n",
                        ret);
        else
                wdd->timeout = wdt_timeout[da9063_wdt_timeout_to_sel(timeout)];

        return ret;
}

static int da9063_wdt_restart(struct watchdog_device *wdd, unsigned long action,
                              void *data)
{
        struct da9063 *da9063 = watchdog_get_drvdata(wdd);
        struct i2c_client *client = to_i2c_client(da9063->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 previously be locked by some process unable to release the
         * lock due to interrupts already being disabled at this late stage.
         */
        msg.byte = DA9063_SHUTDOWN;
        ret = __i2c_smbus_xfer(client->adapter, client->addr, client->flags,
                        I2C_SMBUS_WRITE, DA9063_REG_CONTROL_F,
                        I2C_SMBUS_BYTE_DATA, &msg);

        if (ret < 0)
                dev_alert(da9063->dev, "Failed to shutdown (err = %d)\n",
                          ret);

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

        return ret;
}

static const struct watchdog_info da9063_watchdog_info = {
        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
        .identity = "DA9063 Watchdog",
};

static const struct watchdog_ops da9063_watchdog_ops = {
        .owner = THIS_MODULE,
        .start = da9063_wdt_start,
        .stop = da9063_wdt_stop,
        .ping = da9063_wdt_ping,
        .set_timeout = da9063_wdt_set_timeout,
        .restart = da9063_wdt_restart,
};

static int da9063_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct da9063 *da9063;
        struct watchdog_device *wdd;
        unsigned int timeout;

        if (!dev->parent)
                return -EINVAL;

        da9063 = dev_get_drvdata(dev->parent);
        if (!da9063)
                return -EINVAL;

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

        da9063->use_sw_pm = device_property_present(dev, "dlg,use-sw-pm");

        wdd->info = &da9063_watchdog_info;
        wdd->ops = &da9063_watchdog_ops;
        wdd->min_timeout = DA9063_WDT_MIN_TIMEOUT;
        wdd->max_timeout = DA9063_WDT_MAX_TIMEOUT;
        wdd->min_hw_heartbeat_ms = DA9063_RESET_PROTECTION_MS;
        wdd->parent = dev;
        wdd->status = WATCHDOG_NOWAYOUT_INIT_STATUS;

        watchdog_set_restart_priority(wdd, 128);
        watchdog_set_drvdata(wdd, da9063);
        dev_set_drvdata(dev, wdd);

        wdd->timeout = DA9063_WDG_TIMEOUT;

        /* Use pre-configured timeout if watchdog is already running. */
        timeout = da9063_wdt_read_timeout(da9063);
        if (timeout)
                wdd->timeout = timeout;

        /* Set timeout, maybe override it with DT value, scale it */
        watchdog_init_timeout(wdd, 0, dev);
        da9063_wdt_set_timeout(wdd, wdd->timeout);

        /* Update timeout if the watchdog is already running. */
        if (timeout) {
                da9063_wdt_update_timeout(da9063, wdd->timeout);
                set_bit(WDOG_HW_RUNNING, &wdd->status);
        }

        return devm_watchdog_register_device(dev, wdd);
}

static int da9063_wdt_suspend(struct device *dev)
{
        struct watchdog_device *wdd = dev_get_drvdata(dev);
        struct da9063 *da9063 = watchdog_get_drvdata(wdd);

        if (!da9063->use_sw_pm)
                return 0;

        if (watchdog_active(wdd))
                return da9063_wdt_stop(wdd);

        return 0;
}

static int da9063_wdt_resume(struct device *dev)
{
        struct watchdog_device *wdd = dev_get_drvdata(dev);
        struct da9063 *da9063 = watchdog_get_drvdata(wdd);

        if (!da9063->use_sw_pm)
                return 0;

        if (watchdog_active(wdd))
                return da9063_wdt_start(wdd);

        return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(da9063_wdt_pm_ops, da9063_wdt_suspend,
                                da9063_wdt_resume);

static struct platform_driver da9063_wdt_driver = {
        .probe = da9063_wdt_probe,
        .driver = {
                .name = DA9063_DRVNAME_WATCHDOG,
                .pm = pm_sleep_ptr(&da9063_wdt_pm_ops),
        },
};
module_platform_driver(da9063_wdt_driver);

MODULE_AUTHOR("Mariusz Wojtasik <mariusz.wojtasik@diasemi.com>");
MODULE_DESCRIPTION("Watchdog driver for Dialog DA9063");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DA9063_DRVNAME_WATCHDOG);