// SPDX-License-Identifier: GPL-2.0+
/*
 *      intel TCO Watchdog Driver
 *
 *      (c) Copyright 2006-2011 Wim Van Sebroeck <wim@iguana.be>.
 *
 *      Neither Wim Van Sebroeck nor Iguana vzw. admit liability nor
 *      provide warranty for any of this software. This material is
 *      provided "AS-IS" and at no charge.
 *
 *      The TCO watchdog is implemented in the following I/O controller hubs:
 *      (See the intel documentation on http://developer.intel.com.)
 *      document number 290655-003, 290677-014: 82801AA (ICH), 82801AB (ICHO)
 *      document number 290687-002, 298242-027: 82801BA (ICH2)
 *      document number 290733-003, 290739-013: 82801CA (ICH3-S)
 *      document number 290716-001, 290718-007: 82801CAM (ICH3-M)
 *      document number 290744-001, 290745-025: 82801DB (ICH4)
 *      document number 252337-001, 252663-008: 82801DBM (ICH4-M)
 *      document number 273599-001, 273645-002: 82801E (C-ICH)
 *      document number 252516-001, 252517-028: 82801EB (ICH5), 82801ER (ICH5R)
 *      document number 300641-004, 300884-013: 6300ESB
 *      document number 301473-002, 301474-026: 82801F (ICH6)
 *      document number 313082-001, 313075-006: 631xESB, 632xESB
 *      document number 307013-003, 307014-024: 82801G (ICH7)
 *      document number 322896-001, 322897-001: NM10
 *      document number 313056-003, 313057-017: 82801H (ICH8)
 *      document number 316972-004, 316973-012: 82801I (ICH9)
 *      document number 319973-002, 319974-002: 82801J (ICH10)
 *      document number 322169-001, 322170-003: 5 Series, 3400 Series (PCH)
 *      document number 320066-003, 320257-008: EP80597 (IICH)
 *      document number 324645-001, 324646-001: Cougar Point (CPT)
 *      document number TBD                   : Patsburg (PBG)
 *      document number TBD                   : DH89xxCC
 *      document number TBD                   : Panther Point
 *      document number TBD                   : Lynx Point
 *      document number TBD                   : Lynx Point-LP
 */

/*
 *      Includes, defines, variables, module parameters, ...
 */

/* Module and version information */
#define DRV_NAME        "iTCO_wdt"
#define DRV_VERSION     "1.11"

/* Includes */
#include <linux/acpi.h>                 /* For ACPI support */
#include <linux/bits.h>                 /* For BIT() */
#include <linux/module.h>               /* For module specific items */
#include <linux/moduleparam.h>          /* For new moduleparam's */
#include <linux/types.h>                /* For standard types (like size_t) */
#include <linux/errno.h>                /* For the -ENODEV/... values */
#include <linux/kernel.h>               /* For printk/panic/... */
#include <linux/watchdog.h>             /* For the watchdog specific items */
#include <linux/init.h>                 /* For __init/__exit/... */
#include <linux/fs.h>                   /* For file operations */
#include <linux/platform_device.h>      /* For platform_driver framework */
#include <linux/pci.h>                  /* For pci functions */
#include <linux/ioport.h>               /* For io-port access */
#include <linux/uaccess.h>              /* For copy_to_user/put_user/... */
#include <linux/io.h>                   /* For inb/outb/... */
#include <linux/platform_data/itco_wdt.h>
#include <linux/mfd/intel_pmc_bxt.h>

/* Address definitions for the TCO */
/* TCO base address */
#define TCOBASE(p)      ((p)->tco_res->start)
/* SMI Control and Enable Register */
#define SMI_EN(p)       ((p)->smi_res->start)

#define TCO_RLD(p)      (TCOBASE(p) + 0x00) /* TCO Timer Reload/Curr. Value */
#define TCOv1_TMR(p)    (TCOBASE(p) + 0x01) /* TCOv1 Timer Initial Value*/
#define TCO_DAT_IN(p)   (TCOBASE(p) + 0x02) /* TCO Data In Register     */
#define TCO_DAT_OUT(p)  (TCOBASE(p) + 0x03) /* TCO Data Out Register    */
#define TCO1_STS(p)     (TCOBASE(p) + 0x04) /* TCO1 Status Register     */
#define TCO2_STS(p)     (TCOBASE(p) + 0x06) /* TCO2 Status Register     */
#define TCO1_CNT(p)     (TCOBASE(p) + 0x08) /* TCO1 Control Register    */
#define TCO2_CNT(p)     (TCOBASE(p) + 0x0a) /* TCO2 Control Register    */
#define TCOv2_TMR(p)    (TCOBASE(p) + 0x12) /* TCOv2 Timer Initial Value*/

/*
 * NMI_NOW is bit 8 of TCO1_CNT register
 * Read/Write
 * This bit is implemented as RW but has no effect on HW.
 */
#define NMI_NOW         BIT(8)

/* internal variables */
struct iTCO_wdt_private {
        struct watchdog_device wddev;

        /* TCO version/generation */
        unsigned int iTCO_version;
        struct resource *tco_res;
        struct resource *smi_res;
        /*
         * NO_REBOOT flag is Memory-Mapped GCS register bit 5 (TCO version 2),
         * or memory-mapped PMC register bit 4 (TCO version 3).
         */
        unsigned long __iomem *gcs_pmc;
        /* the PCI-device */
        struct pci_dev *pci_dev;
        /* whether or not the watchdog has been suspended */
        bool suspended;
        /* no reboot API private data */
        void *no_reboot_priv;
        /* no reboot update function pointer */
        int (*update_no_reboot_bit)(void *p, bool set);
};

/* module parameters */
#define WATCHDOG_TIMEOUT 30     /* 30 sec default heartbeat */
static int heartbeat = WATCHDOG_TIMEOUT;  /* in seconds */
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog timeout in seconds. "
        "5..76 (TCO v1) or 3..614 (TCO v2), 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) ")");

static int turn_SMI_watchdog_clear_off = 1;
module_param(turn_SMI_watchdog_clear_off, int, 0);
MODULE_PARM_DESC(turn_SMI_watchdog_clear_off,
        "Turn off SMI clearing watchdog (depends on TCO-version)(default=1)");

/*
 * Some TCO specific functions
 */

/*
 * The iTCO v1 and v2's internal timer is stored as ticks which decrement
 * every 0.6 seconds.  v3's internal timer is stored as seconds (some
 * datasheets incorrectly state 0.6 seconds).
 */
static inline unsigned int seconds_to_ticks(struct iTCO_wdt_private *p,
                                            int secs)
{
        return p->iTCO_version == 3 ? secs : (secs * 10) / 6;
}

static inline unsigned int ticks_to_seconds(struct iTCO_wdt_private *p,
                                            int ticks)
{
        return p->iTCO_version == 3 ? ticks : (ticks * 6) / 10;
}

static inline u32 no_reboot_bit(struct iTCO_wdt_private *p)
{
        u32 enable_bit;

        switch (p->iTCO_version) {
        case 5:
        case 3:
                enable_bit = 0x00000010;
                break;
        case 2:
                enable_bit = 0x00000020;
                break;
        case 4:
        case 1:
        default:
                enable_bit = 0x00000002;
                break;
        }

        return enable_bit;
}

static int update_no_reboot_bit_def(void *priv, bool set)
{
        return 0;
}

static int update_no_reboot_bit_pci(void *priv, bool set)
{
        struct iTCO_wdt_private *p = priv;
        u32 val32 = 0, newval32 = 0;

        pci_read_config_dword(p->pci_dev, 0xd4, &val32);
        if (set)
                val32 |= no_reboot_bit(p);
        else
                val32 &= ~no_reboot_bit(p);
        pci_write_config_dword(p->pci_dev, 0xd4, val32);
        pci_read_config_dword(p->pci_dev, 0xd4, &newval32);

        /* make sure the update is successful */
        if (val32 != newval32)
                return -EIO;

        return 0;
}

static int update_no_reboot_bit_mem(void *priv, bool set)
{
        struct iTCO_wdt_private *p = priv;
        u32 val32 = 0, newval32 = 0;

        val32 = readl(p->gcs_pmc);
        if (set)
                val32 |= no_reboot_bit(p);
        else
                val32 &= ~no_reboot_bit(p);
        writel(val32, p->gcs_pmc);
        newval32 = readl(p->gcs_pmc);

        /* make sure the update is successful */
        if (val32 != newval32)
                return -EIO;

        return 0;
}

static int update_no_reboot_bit_cnt(void *priv, bool set)
{
        struct iTCO_wdt_private *p = priv;
        u16 val, newval;

        /*
         * writing back 1b1 to NMI_NOW of TCO1_CNT register
         * causes NMI_NOW bit inversion what consequently does
         * not allow to perform the register's value comparison
         * properly.
         *
         * NMI_NOW bit masking for TCO1_CNT register values
         * helps to avoid possible NMI_NOW bit inversions on
         * following write operation.
         */
        val = inw(TCO1_CNT(p)) & ~NMI_NOW;
        if (set)
                val |= BIT(0);
        else
                val &= ~BIT(0);
        outw(val, TCO1_CNT(p));
        newval = inw(TCO1_CNT(p)) & ~NMI_NOW;

        /* make sure the update is successful */
        return val != newval ? -EIO : 0;
}

static int update_no_reboot_bit_pmc(void *priv, bool set)
{
        struct intel_pmc_dev *pmc = priv;
        u32 bits = PMC_CFG_NO_REBOOT_EN;
        u32 value = set ? bits : 0;

        return intel_pmc_gcr_update(pmc, PMC_GCR_PMC_CFG_REG, bits, value);
}

static void iTCO_wdt_no_reboot_bit_setup(struct iTCO_wdt_private *p,
                                         struct platform_device *pdev,
                                         struct itco_wdt_platform_data *pdata)
{
        if (pdata->no_reboot_use_pmc) {
                struct intel_pmc_dev *pmc = dev_get_drvdata(pdev->dev.parent);

                p->update_no_reboot_bit = update_no_reboot_bit_pmc;
                p->no_reboot_priv = pmc;
                return;
        }

        if (p->iTCO_version >= 6)
                p->update_no_reboot_bit = update_no_reboot_bit_cnt;
        else if (p->iTCO_version >= 2)
                p->update_no_reboot_bit = update_no_reboot_bit_mem;
        else if (p->iTCO_version == 1)
                p->update_no_reboot_bit = update_no_reboot_bit_pci;
        else
                p->update_no_reboot_bit = update_no_reboot_bit_def;

        p->no_reboot_priv = p;
}

static int iTCO_wdt_start(struct watchdog_device *wd_dev)
{
        struct iTCO_wdt_private *p = watchdog_get_drvdata(wd_dev);
        unsigned int val;

        /* disable chipset's NO_REBOOT bit */
        if (p->update_no_reboot_bit(p->no_reboot_priv, false)) {
                dev_err(wd_dev->parent, "failed to reset NO_REBOOT flag, reboot disabled by hardware/BIOS\n");
                return -EIO;
        }

        /* Force the timer to its reload value by writing to the TCO_RLD
           register */
        if (p->iTCO_version >= 2)
                outw(0x01, TCO_RLD(p));
        else if (p->iTCO_version == 1)
                outb(0x01, TCO_RLD(p));

        /* Bit 11: TCO Timer Halt -> 0 = The TCO timer is enabled to count */
        val = inw(TCO1_CNT(p));
        val &= 0xf7ff;
        outw(val, TCO1_CNT(p));
        val = inw(TCO1_CNT(p));

        if (val & 0x0800)
                return -1;
        return 0;
}

static int iTCO_wdt_stop(struct watchdog_device *wd_dev)
{
        struct iTCO_wdt_private *p = watchdog_get_drvdata(wd_dev);
        unsigned int val;

        /* Bit 11: TCO Timer Halt -> 1 = The TCO timer is disabled */
        val = inw(TCO1_CNT(p));
        val |= 0x0800;
        outw(val, TCO1_CNT(p));
        val = inw(TCO1_CNT(p));

        /* Set the NO_REBOOT bit to prevent later reboots, just for sure */
        p->update_no_reboot_bit(p->no_reboot_priv, true);

        if ((val & 0x0800) == 0)
                return -1;
        return 0;
}

static int iTCO_wdt_ping(struct watchdog_device *wd_dev)
{
        struct iTCO_wdt_private *p = watchdog_get_drvdata(wd_dev);

        /* Reload the timer by writing to the TCO Timer Counter register */
        if (p->iTCO_version >= 2) {
                outw(0x01, TCO_RLD(p));
        } else if (p->iTCO_version == 1) {
                /* Reset the timeout status bit so that the timer
                 * needs to count down twice again before rebooting */
                outw(0x0008, TCO1_STS(p));      /* write 1 to clear bit */

                outb(0x01, TCO_RLD(p));
        }

        return 0;
}

static int iTCO_wdt_set_timeout(struct watchdog_device *wd_dev, unsigned int t)
{
        struct iTCO_wdt_private *p = watchdog_get_drvdata(wd_dev);
        unsigned int val16;
        unsigned char val8;
        unsigned int tmrval;

        tmrval = seconds_to_ticks(p, t);

        /* For TCO v1 the timer counts down twice before rebooting */
        if (p->iTCO_version == 1)
                tmrval /= 2;

        /* from the specs: */
        /* "Values of 0h-3h are ignored and should not be attempted" */
        if (tmrval < 0x04)
                return -EINVAL;
        if ((p->iTCO_version >= 2 && tmrval > 0x3ff) ||
            (p->iTCO_version == 1 && tmrval > 0x03f))
                return -EINVAL;

        /* Write new heartbeat to watchdog */
        if (p->iTCO_version >= 2) {
                val16 = inw(TCOv2_TMR(p));
                val16 &= 0xfc00;
                val16 |= tmrval;
                outw(val16, TCOv2_TMR(p));
                val16 = inw(TCOv2_TMR(p));

                if ((val16 & 0x3ff) != tmrval)
                        return -EINVAL;
        } else if (p->iTCO_version == 1) {
                val8 = inb(TCOv1_TMR(p));
                val8 &= 0xc0;
                val8 |= (tmrval & 0xff);
                outb(val8, TCOv1_TMR(p));
                val8 = inb(TCOv1_TMR(p));

                if ((val8 & 0x3f) != tmrval)
                        return -EINVAL;
        }

        wd_dev->timeout = t;
        return 0;
}

static unsigned int iTCO_wdt_get_timeleft(struct watchdog_device *wd_dev)
{
        struct iTCO_wdt_private *p = watchdog_get_drvdata(wd_dev);
        unsigned int val16;
        unsigned char val8;
        unsigned int time_left = 0;

        /* read the TCO Timer */
        if (p->iTCO_version >= 2) {
                val16 = inw(TCO_RLD(p));
                val16 &= 0x3ff;

                time_left = ticks_to_seconds(p, val16);
        } else if (p->iTCO_version == 1) {
                val8 = inb(TCO_RLD(p));
                val8 &= 0x3f;
                if (!(inw(TCO1_STS(p)) & 0x0008))
                        val8 += (inb(TCOv1_TMR(p)) & 0x3f);

                time_left = ticks_to_seconds(p, val8);
        }
        return time_left;
}

/* Returns true if the watchdog was running */
static bool iTCO_wdt_set_running(struct iTCO_wdt_private *p)
{
        u16 val;

        /* Bit 11: TCO Timer Halt -> 0 = The TCO timer is enabled */
        val = inw(TCO1_CNT(p));
        if (!(val & BIT(11))) {
                set_bit(WDOG_HW_RUNNING, &p->wddev.status);
                return true;
        }
        return false;
}

/*
 *      Kernel Interfaces
 */

static struct watchdog_info ident = {
        .options =              WDIOF_SETTIMEOUT |
                                WDIOF_KEEPALIVEPING |
                                WDIOF_MAGICCLOSE,
        .identity =             DRV_NAME,
};

static const struct watchdog_ops iTCO_wdt_ops = {
        .owner =                THIS_MODULE,
        .start =                iTCO_wdt_start,
        .stop =                 iTCO_wdt_stop,
        .ping =                 iTCO_wdt_ping,
        .set_timeout =          iTCO_wdt_set_timeout,
        .get_timeleft =         iTCO_wdt_get_timeleft,
};

/*
 *      Init & exit routines
 */

static int iTCO_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct itco_wdt_platform_data *pdata = dev_get_platdata(dev);
        struct iTCO_wdt_private *p;
        unsigned long val32;
        int ret;

        if (!pdata)
                return -ENODEV;

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

        p->tco_res = platform_get_resource(pdev, IORESOURCE_IO, ICH_RES_IO_TCO);
        if (!p->tco_res)
                return -ENODEV;

        p->iTCO_version = pdata->version;
        p->pci_dev = to_pci_dev(dev->parent);

        p->smi_res = platform_get_resource(pdev, IORESOURCE_IO, ICH_RES_IO_SMI);
        if (p->smi_res) {
                /* The TCO logic uses the TCO_EN bit in the SMI_EN register */
                if (!devm_request_region(dev, p->smi_res->start,
                                         resource_size(p->smi_res),
                                         pdev->name)) {
                        dev_err(dev, "I/O address 0x%04llx already in use, device disabled\n",
                               (u64)SMI_EN(p));
                        return -EBUSY;
                }
        } else if (turn_SMI_watchdog_clear_off >= p->iTCO_version) {
                dev_err(dev, "SMI I/O resource is missing\n");
                return -ENODEV;
        }

        iTCO_wdt_no_reboot_bit_setup(p, pdev, pdata);

        /*
         * Get the Memory-Mapped GCS or PMC register, we need it for the
         * NO_REBOOT flag (TCO v2 and v3).
         */
        if (p->iTCO_version >= 2 && p->iTCO_version < 6 &&
            !pdata->no_reboot_use_pmc) {
                p->gcs_pmc = devm_platform_ioremap_resource(pdev, ICH_RES_MEM_GCS_PMC);
                if (IS_ERR(p->gcs_pmc))
                        return PTR_ERR(p->gcs_pmc);
        }

        /* Check chipset's NO_REBOOT bit */
        if (p->update_no_reboot_bit(p->no_reboot_priv, false)) {
                dev_info(dev, "unable to reset NO_REBOOT flag, device disabled by hardware/BIOS\n");
                return -ENODEV; /* Cannot reset NO_REBOOT bit */
        }

        if (turn_SMI_watchdog_clear_off >= p->iTCO_version) {
                /*
                 * Bit 13: TCO_EN -> 0
                 * Disables TCO logic generating an SMI#
                 */
                val32 = inl(SMI_EN(p));
                val32 &= 0xffffdfff;    /* Turn off SMI clearing watchdog */
                outl(val32, SMI_EN(p));
        }

        if (!devm_request_region(dev, p->tco_res->start,
                                 resource_size(p->tco_res),
                                 pdev->name)) {
                dev_err(dev, "I/O address 0x%04llx already in use, device disabled\n",
                       (u64)TCOBASE(p));
                return -EBUSY;
        }

        dev_info(dev, "Found a %s TCO device (Version=%d, TCOBASE=0x%04llx)\n",
                pdata->name, pdata->version, (u64)TCOBASE(p));

        /* Clear out the (probably old) status */
        switch (p->iTCO_version) {
        case 6:
        case 5:
        case 4:
                outw(0x0008, TCO1_STS(p)); /* Clear the Time Out Status bit */
                outw(0x0002, TCO2_STS(p)); /* Clear SECOND_TO_STS bit */
                break;
        case 3:
                outl(0x20008, TCO1_STS(p));
                break;
        case 2:
        case 1:
        default:
                outw(0x0008, TCO1_STS(p)); /* Clear the Time Out Status bit */
                outw(0x0002, TCO2_STS(p)); /* Clear SECOND_TO_STS bit */
                outw(0x0004, TCO2_STS(p)); /* Clear BOOT_STS bit */
                break;
        }

        ident.firmware_version = p->iTCO_version;
        p->wddev.info = &ident;
        p->wddev.ops = &iTCO_wdt_ops;
        p->wddev.bootstatus = 0;
        p->wddev.timeout = WATCHDOG_TIMEOUT;
        watchdog_set_nowayout(&p->wddev, nowayout);
        p->wddev.parent = dev;

        watchdog_set_drvdata(&p->wddev, p);
        platform_set_drvdata(pdev, p);

        if (!iTCO_wdt_set_running(p)) {
                /*
                 * If the watchdog was not running set NO_REBOOT now to
                 * prevent later reboots.
                 */
                p->update_no_reboot_bit(p->no_reboot_priv, true);
        }

        /* Check that the heartbeat value is within it's range;
           if not reset to the default */
        if (iTCO_wdt_set_timeout(&p->wddev, heartbeat)) {
                ret = iTCO_wdt_set_timeout(&p->wddev, WATCHDOG_TIMEOUT);
                if (ret != 0) {
                        dev_err(dev, "Failed to set watchdog timeout (%d)\n", WATCHDOG_TIMEOUT);
                        return ret;
                }
                dev_info(dev, "timeout value out of range, using %d\n",
                        WATCHDOG_TIMEOUT);
                heartbeat = WATCHDOG_TIMEOUT;
        }

        watchdog_stop_on_reboot(&p->wddev);
        watchdog_stop_on_unregister(&p->wddev);
        ret = devm_watchdog_register_device(dev, &p->wddev);
        if (ret != 0)
                return ret;

        dev_info(dev, "initialized. heartbeat=%d sec (nowayout=%d)\n",
                heartbeat, nowayout);

        return 0;
}

/*
 * Suspend-to-idle requires this, because it stops the ticks and timekeeping, so
 * the watchdog cannot be pinged while in that state.  In ACPI sleep states the
 * watchdog is stopped by the platform firmware.
 */

#ifdef CONFIG_ACPI
static inline bool __maybe_unused need_suspend(void)
{
        return acpi_target_system_state() == ACPI_STATE_S0;
}
#else
static inline bool __maybe_unused need_suspend(void) { return true; }
#endif

static int __maybe_unused iTCO_wdt_suspend_noirq(struct device *dev)
{
        struct iTCO_wdt_private *p = dev_get_drvdata(dev);
        int ret = 0;

        p->suspended = false;
        if (watchdog_active(&p->wddev) && need_suspend()) {
                ret = iTCO_wdt_stop(&p->wddev);
                if (!ret)
                        p->suspended = true;
        }
        return ret;
}

static int __maybe_unused iTCO_wdt_resume_noirq(struct device *dev)
{
        struct iTCO_wdt_private *p = dev_get_drvdata(dev);

        if (p->suspended)
                iTCO_wdt_start(&p->wddev);

        return 0;
}

static const struct dev_pm_ops iTCO_wdt_pm = {
        SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(iTCO_wdt_suspend_noirq,
                                      iTCO_wdt_resume_noirq)
};

static struct platform_driver iTCO_wdt_driver = {
        .probe          = iTCO_wdt_probe,
        .driver         = {
                .name   = DRV_NAME,
                .pm     = &iTCO_wdt_pm,
        },
};

module_platform_driver(iTCO_wdt_driver);

MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
MODULE_DESCRIPTION("Intel TCO WatchDog Timer Driver");
MODULE_VERSION(DRV_VERSION);
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);