// SPDX-License-Identifier: GPL-2.0-only
/*
 * Maxim MAX77620 Watchdog Driver
 *
 * Copyright (C) 2016 NVIDIA CORPORATION. All rights reserved.
 * Copyright (C) 2022 Luca Ceresoli
 *
 * Author: Laxman Dewangan <ldewangan@nvidia.com>
 * Author: Luca Ceresoli <luca.ceresoli@bootlin.com>
 */

#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/mfd/max77620.h>
#include <linux/mfd/max77714.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/watchdog.h>

static bool nowayout = WATCHDOG_NOWAYOUT;

/**
 * struct max77620_variant - Data specific to a chip variant
 * @wdt_info:            watchdog descriptor
 * @reg_onoff_cnfg2:     ONOFF_CNFG2 register offset
 * @reg_cnfg_glbl2:      CNFG_GLBL2 register offset
 * @reg_cnfg_glbl3:      CNFG_GLBL3 register offset
 * @wdtc_mask:           WDTC bit mask in CNFG_GLBL3 (=bits to update to ping the watchdog)
 * @bit_wd_rst_wk:       WD_RST_WK bit offset within ONOFF_CNFG2
 * @cnfg_glbl2_cfg_bits: configuration bits to enable in CNFG_GLBL2 register
 */
struct max77620_variant {
	u8 reg_onoff_cnfg2;
	u8 reg_cnfg_glbl2;
	u8 reg_cnfg_glbl3;
	u8 wdtc_mask;
	u8 bit_wd_rst_wk;
	u8 cnfg_glbl2_cfg_bits;
};

struct max77620_wdt {
	struct device			*dev;
	struct regmap			*rmap;
	const struct max77620_variant	*drv_data;
	struct watchdog_device		wdt_dev;
};

static const struct max77620_variant max77620_wdt_data = {
	.reg_onoff_cnfg2     = MAX77620_REG_ONOFFCNFG2,
	.reg_cnfg_glbl2      = MAX77620_REG_CNFGGLBL2,
	.reg_cnfg_glbl3      = MAX77620_REG_CNFGGLBL3,
	.wdtc_mask           = MAX77620_WDTC_MASK,
	.bit_wd_rst_wk       = MAX77620_ONOFFCNFG2_WD_RST_WK,
	/* Set WDT clear in OFF and sleep mode */
	.cnfg_glbl2_cfg_bits = MAX77620_WDTSLPC | MAX77620_WDTOFFC,
};

static const struct max77620_variant max77714_wdt_data = {
	.reg_onoff_cnfg2     = MAX77714_CNFG2_ONOFF,
	.reg_cnfg_glbl2      = MAX77714_CNFG_GLBL2,
	.reg_cnfg_glbl3      = MAX77714_CNFG_GLBL3,
	.wdtc_mask           = MAX77714_WDTC,
	.bit_wd_rst_wk       = MAX77714_WD_RST_WK,
	/* Set WDT clear in sleep mode (there is no WDTOFFC on MAX77714) */
	.cnfg_glbl2_cfg_bits = MAX77714_WDTSLPC,
};

static int max77620_wdt_start(struct watchdog_device *wdt_dev)
{
	struct max77620_wdt *wdt = watchdog_get_drvdata(wdt_dev);

	return regmap_update_bits(wdt->rmap, wdt->drv_data->reg_cnfg_glbl2,
				  MAX77620_WDTEN, MAX77620_WDTEN);
}

static int max77620_wdt_stop(struct watchdog_device *wdt_dev)
{
	struct max77620_wdt *wdt = watchdog_get_drvdata(wdt_dev);

	return regmap_update_bits(wdt->rmap, wdt->drv_data->reg_cnfg_glbl2,
				  MAX77620_WDTEN, 0);
}

static int max77620_wdt_ping(struct watchdog_device *wdt_dev)
{
	struct max77620_wdt *wdt = watchdog_get_drvdata(wdt_dev);

	return regmap_update_bits(wdt->rmap, wdt->drv_data->reg_cnfg_glbl3,
				  wdt->drv_data->wdtc_mask, 0x1);
}

static int max77620_wdt_set_timeout(struct watchdog_device *wdt_dev,
				    unsigned int timeout)
{
	struct max77620_wdt *wdt = watchdog_get_drvdata(wdt_dev);
	unsigned int wdt_timeout;
	u8 regval;
	int ret;

	switch (timeout) {
	case 0 ... 2:
		regval = MAX77620_TWD_2s;
		wdt_timeout = 2;
		break;

	case 3 ... 16:
		regval = MAX77620_TWD_16s;
		wdt_timeout = 16;
		break;

	case 17 ... 64:
		regval = MAX77620_TWD_64s;
		wdt_timeout = 64;
		break;

	default:
		regval = MAX77620_TWD_128s;
		wdt_timeout = 128;
		break;
	}

	/*
	 * "If the value of TWD needs to be changed, clear the system
	 * watchdog timer first [...], then change the value of TWD."
	 * (MAX77714 datasheet but applies to MAX77620 too)
	 */
	ret = regmap_update_bits(wdt->rmap, wdt->drv_data->reg_cnfg_glbl3,
				 wdt->drv_data->wdtc_mask, 0x1);
	if (ret < 0)
		return ret;

	ret = regmap_update_bits(wdt->rmap, wdt->drv_data->reg_cnfg_glbl2,
				 MAX77620_TWD_MASK, regval);
	if (ret < 0)
		return ret;

	wdt_dev->timeout = wdt_timeout;

	return 0;
}

static const struct watchdog_info max77620_wdt_info = {
	.identity = "max77620-watchdog",
	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
};

static const struct watchdog_ops max77620_wdt_ops = {
	.start		= max77620_wdt_start,
	.stop		= max77620_wdt_stop,
	.ping		= max77620_wdt_ping,
	.set_timeout	= max77620_wdt_set_timeout,
};

static int max77620_wdt_probe(struct platform_device *pdev)
{
	const struct platform_device_id *id = platform_get_device_id(pdev);
	struct device *dev = &pdev->dev;
	struct max77620_wdt *wdt;
	struct watchdog_device *wdt_dev;
	unsigned int regval;
	int ret;

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

	wdt->dev = dev;
	wdt->drv_data = (const struct max77620_variant *) id->driver_data;

	wdt->rmap = dev_get_regmap(dev->parent, NULL);
	if (!wdt->rmap) {
		dev_err(wdt->dev, "Failed to get parent regmap\n");
		return -ENODEV;
	}

	wdt_dev = &wdt->wdt_dev;
	wdt_dev->info = &max77620_wdt_info;
	wdt_dev->ops = &max77620_wdt_ops;
	wdt_dev->min_timeout = 2;
	wdt_dev->max_timeout = 128;
	wdt_dev->max_hw_heartbeat_ms = 128 * 1000;

	platform_set_drvdata(pdev, wdt);

	/* Enable WD_RST_WK - WDT expire results in a restart */
	ret = regmap_update_bits(wdt->rmap, wdt->drv_data->reg_onoff_cnfg2,
				 wdt->drv_data->bit_wd_rst_wk,
				 wdt->drv_data->bit_wd_rst_wk);
	if (ret < 0) {
		dev_err(wdt->dev, "Failed to set WD_RST_WK: %d\n", ret);
		return ret;
	}

	/* Set the "auto WDT clear" bits available on the chip */
	ret = regmap_update_bits(wdt->rmap, wdt->drv_data->reg_cnfg_glbl2,
				 wdt->drv_data->cnfg_glbl2_cfg_bits,
				 wdt->drv_data->cnfg_glbl2_cfg_bits);
	if (ret < 0) {
		dev_err(wdt->dev, "Failed to set WDT OFF mode: %d\n", ret);
		return ret;
	}

	/* Check if WDT running and if yes then set flags properly */
	ret = regmap_read(wdt->rmap, wdt->drv_data->reg_cnfg_glbl2, &regval);
	if (ret < 0) {
		dev_err(wdt->dev, "Failed to read WDT CFG register: %d\n", ret);
		return ret;
	}

	switch (regval & MAX77620_TWD_MASK) {
	case MAX77620_TWD_2s:
		wdt_dev->timeout = 2;
		break;
	case MAX77620_TWD_16s:
		wdt_dev->timeout = 16;
		break;
	case MAX77620_TWD_64s:
		wdt_dev->timeout = 64;
		break;
	default:
		wdt_dev->timeout = 128;
		break;
	}

	if (regval & MAX77620_WDTEN)
		set_bit(WDOG_HW_RUNNING, &wdt_dev->status);

	watchdog_set_nowayout(wdt_dev, nowayout);
	watchdog_set_drvdata(wdt_dev, wdt);

	watchdog_stop_on_unregister(wdt_dev);
	return devm_watchdog_register_device(dev, wdt_dev);
}

static const struct platform_device_id max77620_wdt_devtype[] = {
	{ "max77620-watchdog", (kernel_ulong_t)&max77620_wdt_data },
	{ "max77714-watchdog", (kernel_ulong_t)&max77714_wdt_data },
	{ },
};
MODULE_DEVICE_TABLE(platform, max77620_wdt_devtype);

static struct platform_driver max77620_wdt_driver = {
	.driver	= {
		.name	= "max77620-watchdog",
	},
	.probe	= max77620_wdt_probe,
	.id_table = max77620_wdt_devtype,
};

module_platform_driver(max77620_wdt_driver);

MODULE_DESCRIPTION("Max77620 watchdog timer driver");

module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
MODULE_AUTHOR("Luca Ceresoli <luca.ceresoli@bootlin.com>");
MODULE_LICENSE("GPL v2");