// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * WDT driver for Lenovo SE10.
 */

#include <linux/delay.h>
#include <linux/dmi.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/watchdog.h>

#define STATUS_PORT     0x6C
#define CMD_PORT        0x6C
#define DATA_PORT       0x68
#define OUTBUF_FULL     0x01
#define INBUF_EMPTY     0x02
#define CFG_LDN         0x07
#define CFG_BRAM_LDN    0x10 /* for BRAM Base */
#define CFG_PORT        0x2E
#define CFG_SIZE           2
#define CMD_SIZE           4
#define BRAM_SIZE          2

#define UNLOCK_KEY      0x87
#define LOCK_KEY        0xAA

#define CUS_WDT_SWI     0x1A
#define CUS_WDT_CFG     0x1B
#define CUS_WDT_FEED    0xB0
#define CUS_WDT_CNT     0xB1

#define DRVNAME "lenovo-se10-wdt"

/*The timeout range is 1-255 seconds*/
#define MIN_TIMEOUT 1
#define MAX_TIMEOUT 255
#define MAX_WAIT    10

#define WATCHDOG_TIMEOUT 60 /* 60 sec default timeout */
static unsigned short bram_base;
static struct platform_device *se10_pdev;

static int timeout; /* in seconds */
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
                 "Watchdog timeout in seconds. 1 <= timeout <= 255, default="
                 __MODULE_STRING(WATCHDOG_TIMEOUT) ".");

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

struct se10_wdt {
        struct watchdog_device wdd;
};

static int set_bram(unsigned char offset, unsigned char val)
{
        if (!request_muxed_region(bram_base, BRAM_SIZE, DRVNAME))
                return -EBUSY;
        outb(offset, bram_base);
        outb(val, bram_base + 1);
        release_region(bram_base, BRAM_SIZE);
        return 0;
}

static void wait_for_buffer(int condition)
{
        int loop = 0;

        while (1) {
                if (inb(STATUS_PORT) & condition || loop > MAX_WAIT)
                        break;
                loop++;
                usleep_range(10, 125);
        }
}

static void send_cmd(unsigned char cmd)
{
        wait_for_buffer(INBUF_EMPTY);
        outb(cmd, CMD_PORT);
        wait_for_buffer(INBUF_EMPTY);
}

static void lpc_write(unsigned char index, unsigned char data)
{
        outb(index, CFG_PORT);
        outb(data, CFG_PORT + 1);
}

static unsigned char lpc_read(unsigned char index)
{
        outb(index, CFG_PORT);
        return inb(CFG_PORT + 1);
}

static int wdt_start(struct watchdog_device *wdog)
{
        return set_bram(CUS_WDT_SWI, 0x80);
}

static int wdt_set_timeout(struct watchdog_device *wdog, unsigned int timeout)
{
        wdog->timeout = timeout;
        return set_bram(CUS_WDT_CFG, wdog->timeout);
}

static int wdt_stop(struct watchdog_device *wdog)
{
        return set_bram(CUS_WDT_SWI, 0);
}

static unsigned int wdt_get_time(struct watchdog_device *wdog)
{
        unsigned char time;

        if (!request_muxed_region(CMD_PORT, CMD_SIZE, DRVNAME))
                return -EBUSY;
        send_cmd(CUS_WDT_CNT);
        wait_for_buffer(OUTBUF_FULL);
        time = inb(DATA_PORT);
        release_region(CMD_PORT, CMD_SIZE);
        return time;
}

static int wdt_ping(struct watchdog_device *wdog)
{
        if (!request_muxed_region(CMD_PORT, CMD_SIZE, DRVNAME))
                return -EBUSY;
        send_cmd(CUS_WDT_FEED);
        release_region(CMD_PORT, CMD_SIZE);
        return 0;
}

static const struct watchdog_info wdt_info = {
        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
        .identity = "Lenovo SE10 Watchdog",
};

static const struct watchdog_ops se10_wdt_ops = {
        .owner = THIS_MODULE,
        .start = wdt_start,
        .stop = wdt_stop,
        .ping = wdt_ping,
        .set_timeout = wdt_set_timeout,
        .get_timeleft = wdt_get_time,
};

static unsigned int get_chipID(void)
{
        unsigned char msb, lsb;

        outb(UNLOCK_KEY, CFG_PORT);
        outb(0x01, CFG_PORT);
        outb(0x55, CFG_PORT);
        outb(0x55, CFG_PORT);
        msb = lpc_read(0x20);
        lsb = lpc_read(0x21);
        outb(LOCK_KEY, CFG_PORT);
        return (msb * 256 + lsb);
}

static int se10_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct se10_wdt *priv;
        unsigned int chip_id;
        int ret;

        if (!request_muxed_region(CFG_PORT, CFG_SIZE, DRVNAME))
                return -EBUSY;

        chip_id = get_chipID();
        if (chip_id != 0x5632) {
                release_region(CFG_PORT, CFG_SIZE);
                return -ENODEV;
        }

        lpc_write(CFG_LDN, CFG_BRAM_LDN);
        bram_base = (lpc_read(0x60) << 8) | lpc_read(0x61);
        release_region(CFG_PORT, CFG_SIZE);

        dev_info(dev, "Found Lenovo SE10 0x%x\n", chip_id);

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

        watchdog_set_drvdata(&priv->wdd, priv);

        priv->wdd.parent = dev;
        priv->wdd.info = &wdt_info;
        priv->wdd.ops = &se10_wdt_ops;
        priv->wdd.timeout = WATCHDOG_TIMEOUT; /* Set default timeout */
        priv->wdd.min_timeout = MIN_TIMEOUT;
        priv->wdd.max_timeout = MAX_TIMEOUT;

        set_bram(CUS_WDT_CFG, WATCHDOG_TIMEOUT); /* Set time to default */

        watchdog_init_timeout(&priv->wdd, timeout, dev);
        watchdog_set_nowayout(&priv->wdd, nowayout);
        watchdog_stop_on_reboot(&priv->wdd);
        watchdog_stop_on_unregister(&priv->wdd);

        ret = devm_watchdog_register_device(dev, &priv->wdd);

        dev_dbg(&pdev->dev, "initialized. timeout=%d sec (nowayout=%d)\n",
                priv->wdd.timeout, nowayout);

        return ret;
}

static struct platform_driver se10_wdt_driver = {
        .driver = {
                .name = DRVNAME,
        },
        .probe  = se10_wdt_probe,
};

static int se10_create_platform_device(const struct dmi_system_id *id)
{
        int err;

        se10_pdev = platform_device_alloc("lenovo-se10-wdt", -1);
        if (!se10_pdev)
                return -ENOMEM;

        err = platform_device_add(se10_pdev);
        if (err)
                platform_device_put(se10_pdev);

        return err;
}

static const struct dmi_system_id se10_dmi_table[] __initconst = {
        {
                .ident = "LENOVO-SE10",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "12NH"),
                },
                .callback = se10_create_platform_device,
        },
        {
                .ident = "LENOVO-SE10",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "12NJ"),
                },
                .callback = se10_create_platform_device,
        },
        {
                .ident = "LENOVO-SE10",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "12NK"),
                },
                .callback = se10_create_platform_device,
        },
        {
                .ident = "LENOVO-SE10",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "12NL"),
                },
                .callback = se10_create_platform_device,
        },
        {
                .ident = "LENOVO-SE10",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "12NM"),
                },
                .callback = se10_create_platform_device,
        },
        {}
};
MODULE_DEVICE_TABLE(dmi, se10_dmi_table);

static int __init se10_wdt_init(void)
{
        if (!dmi_check_system(se10_dmi_table))
                return -ENODEV;

        return platform_driver_register(&se10_wdt_driver);
}

static void __exit se10_wdt_exit(void)
{
        if (se10_pdev)
                platform_device_unregister(se10_pdev);
        platform_driver_unregister(&se10_wdt_driver);
}

module_init(se10_wdt_init);
module_exit(se10_wdt_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Ober<dober@lenovo.com>");
MODULE_AUTHOR("Mark Pearson <mpearson-lenovo@squebb.ca>");
MODULE_DESCRIPTION("WDT driver for Lenovo SE10");