/*
 *      intel TCO vendor specific watchdog driver support
 *
 *      (c) Copyright 2006-2009 Wim Van Sebroeck <wim@iguana.be>.
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 *      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.
 */

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

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

/* Module and version information */
#define DRV_NAME        "iTCO_vendor_support"
#define DRV_VERSION     "1.04"

/* Includes */
#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/init.h>                 /* For __init/__exit/... */
#include <linux/ioport.h>               /* For io-port access */
#include <linux/io.h>                   /* For inb/outb/... */

#include "iTCO_vendor.h"

/* List of vendor support modes */
/* SuperMicro Pentium 3 Era 370SSE+-OEM1/P3TSSE */
#define SUPERMICRO_OLD_BOARD    1
/* SuperMicro Pentium 4 / Xeon 4 / EMT64T Era Systems */
#define SUPERMICRO_NEW_BOARD    2
/* Broken BIOS */
#define BROKEN_BIOS             911

static int vendorsupport;
module_param(vendorsupport, int, 0);
MODULE_PARM_DESC(vendorsupport, "iTCO vendor specific support mode, default="
                        "0 (none), 1=SuperMicro Pent3, 2=SuperMicro Pent4+, "
                                                        "911=Broken SMI BIOS");

/*
 *      Vendor Specific Support
 */

/*
 *      Vendor Support: 1
 *      Board: Super Micro Computer Inc. 370SSE+-OEM1/P3TSSE
 *      iTCO chipset: ICH2
 *
 *      Code contributed by: R. Seretny <lkpatches@paypc.com>
 *      Documentation obtained by R. Seretny from SuperMicro Technical Support
 *
 *      To enable Watchdog function:
 *          BIOS setup -> Power -> TCO Logic SMI Enable -> Within5Minutes
 *          This setting enables SMI to clear the watchdog expired flag.
 *          If BIOS or CPU fail which may cause SMI hang, then system will
 *          reboot. When application starts to use watchdog function,
 *          application has to take over the control from SMI.
 *
 *          For P3TSSE, J36 jumper needs to be removed to enable the Watchdog
 *          function.
 *
 *          Note: The system will reboot when Expire Flag is set TWICE.
 *          So, if the watchdog timer is 20 seconds, then the maximum hang
 *          time is about 40 seconds, and the minimum hang time is about
 *          20.6 seconds.
 */

static void supermicro_old_pre_start(struct resource *smires)
{
        unsigned long val32;

        /* Bit 13: TCO_EN -> 0 = Disables TCO logic generating an SMI# */
        val32 = inl(smires->start);
        val32 &= 0xffffdfff;    /* Turn off SMI clearing watchdog */
        outl(val32, smires->start);     /* Needed to activate watchdog */
}

static void supermicro_old_pre_stop(struct resource *smires)
{
        unsigned long val32;

        /* Bit 13: TCO_EN -> 1 = Enables the TCO logic to generate SMI# */
        val32 = inl(smires->start);
        val32 |= 0x00002000;    /* Turn on SMI clearing watchdog */
        outl(val32, smires->start);     /* Needed to deactivate watchdog */
}

/*
 *      Vendor Support: 2
 *      Board: Super Micro Computer Inc. P4SBx, P4DPx
 *      iTCO chipset: ICH4
 *
 *      Code contributed by: R. Seretny <lkpatches@paypc.com>
 *      Documentation obtained by R. Seretny from SuperMicro Technical Support
 *
 *      To enable Watchdog function:
 *       1. BIOS
 *        For P4SBx:
 *        BIOS setup -> Advanced -> Integrated Peripherals -> Watch Dog Feature
 *        For P4DPx:
 *        BIOS setup -> Advanced -> I/O Device Configuration -> Watch Dog
 *       This setting enables or disables Watchdog function. When enabled, the
 *       default watchdog timer is set to be 5 minutes (about 4m35s). It is
 *       enough to load and run the OS. The application (service or driver) has
 *       to take over the control once OS is running up and before watchdog
 *       expires.
 *
 *       2. JUMPER
 *        For P4SBx: JP39
 *        For P4DPx: JP37
 *        This jumper is used for safety.  Closed is enabled. This jumper
 *        prevents user enables watchdog in BIOS by accident.
 *
 *       To enable Watch Dog function, both BIOS and JUMPER must be enabled.
 *
 *      The documentation lists motherboards P4SBx and P4DPx series as of
 *      20-March-2002. However, this code works flawlessly with much newer
 *      motherboards, such as my X6DHR-8G2 (SuperServer 6014H-82).
 *
 *      The original iTCO driver as written does not actually reset the
 *      watchdog timer on these machines, as a result they reboot after five
 *      minutes.
 *
 *      NOTE: You may leave the Watchdog function disabled in the SuperMicro
 *      BIOS to avoid a "boot-race"... This driver will enable watchdog
 *      functionality even if it's disabled in the BIOS once the /dev/watchdog
 *      file is opened.
 */

/* I/O Port's */
#define SM_REGINDEX     0x2e    /* SuperMicro ICH4+ Register Index */
#define SM_DATAIO       0x2f    /* SuperMicro ICH4+ Register Data I/O */

/* Control Register's */
#define SM_CTLPAGESW    0x07    /* SuperMicro ICH4+ Control Page Switch */
#define SM_CTLPAGE      0x08    /* SuperMicro ICH4+ Control Page Num */

#define SM_WATCHENABLE  0x30    /* Watchdog enable: Bit 0: 0=off, 1=on */

#define SM_WATCHPAGE    0x87    /* Watchdog unlock control page */

#define SM_ENDWATCH     0xAA    /* Watchdog lock control page */

#define SM_COUNTMODE    0xf5    /* Watchdog count mode select */
                                /* (Bit 3: 0 = seconds, 1 = minutes */

#define SM_WATCHTIMER   0xf6    /* 8-bits, Watchdog timer counter (RW) */

#define SM_RESETCONTROL 0xf7    /* Watchdog reset control */
                                /* Bit 6: timer is reset by kbd interrupt */
                                /* Bit 7: timer is reset by mouse interrupt */

static void supermicro_new_unlock_watchdog(void)
{
        /* Write 0x87 to port 0x2e twice */
        outb(SM_WATCHPAGE, SM_REGINDEX);
        outb(SM_WATCHPAGE, SM_REGINDEX);
        /* Switch to watchdog control page */
        outb(SM_CTLPAGESW, SM_REGINDEX);
        outb(SM_CTLPAGE, SM_DATAIO);
}

static void supermicro_new_lock_watchdog(void)
{
        outb(SM_ENDWATCH, SM_REGINDEX);
}

static void supermicro_new_pre_start(unsigned int heartbeat)
{
        unsigned int val;

        supermicro_new_unlock_watchdog();

        /* Watchdog timer setting needs to be in seconds*/
        outb(SM_COUNTMODE, SM_REGINDEX);
        val = inb(SM_DATAIO);
        val &= 0xF7;
        outb(val, SM_DATAIO);

        /* Write heartbeat interval to WDOG */
        outb(SM_WATCHTIMER, SM_REGINDEX);
        outb((heartbeat & 255), SM_DATAIO);

        /* Make sure keyboard/mouse interrupts don't interfere */
        outb(SM_RESETCONTROL, SM_REGINDEX);
        val = inb(SM_DATAIO);
        val &= 0x3f;
        outb(val, SM_DATAIO);

        /* enable watchdog by setting bit 0 of Watchdog Enable to 1 */
        outb(SM_WATCHENABLE, SM_REGINDEX);
        val = inb(SM_DATAIO);
        val |= 0x01;
        outb(val, SM_DATAIO);

        supermicro_new_lock_watchdog();
}

static void supermicro_new_pre_stop(void)
{
        unsigned int val;

        supermicro_new_unlock_watchdog();

        /* disable watchdog by setting bit 0 of Watchdog Enable to 0 */
        outb(SM_WATCHENABLE, SM_REGINDEX);
        val = inb(SM_DATAIO);
        val &= 0xFE;
        outb(val, SM_DATAIO);

        supermicro_new_lock_watchdog();
}

static void supermicro_new_pre_set_heartbeat(unsigned int heartbeat)
{
        supermicro_new_unlock_watchdog();

        /* reset watchdog timeout to heartveat value */
        outb(SM_WATCHTIMER, SM_REGINDEX);
        outb((heartbeat & 255), SM_DATAIO);

        supermicro_new_lock_watchdog();
}

/*
 *      Vendor Support: 911
 *      Board: Some Intel ICHx based motherboards
 *      iTCO chipset: ICH7+
 *
 *      Some Intel motherboards have a broken BIOS implementation: i.e.
 *      the SMI handler clear's the TIMEOUT bit in the TC01_STS register
 *      and does not reload the time. Thus the TCO watchdog does not reboot
 *      the system.
 *
 *      These are the conclusions of Andriy Gapon <avg@icyb.net.ua> after
 *      debugging: the SMI handler is quite simple - it tests value in
 *      TCO1_CNT against 0x800, i.e. checks TCO_TMR_HLT. If the bit is set
 *      the handler goes into an infinite loop, apparently to allow the
 *      second timeout and reboot. Otherwise it simply clears TIMEOUT bit
 *      in TCO1_STS and that's it.
 *      So the logic seems to be reversed, because it is hard to see how
 *      TIMEOUT can get set to 1 and SMI generated when TCO_TMR_HLT is set
 *      (other than a transitional effect).
 *
 *      The only fix found to get the motherboard(s) to reboot is to put
 *      the glb_smi_en bit to 0. This is a dirty hack that bypasses the
 *      broken code by disabling Global SMI.
 *
 *      WARNING: globally disabling SMI could possibly lead to dramatic
 *      problems, especially on laptops! I.e. various ACPI things where
 *      SMI is used for communication between OS and firmware.
 *
 *      Don't use this fix if you don't need to!!!
 */

static void broken_bios_start(struct resource *smires)
{
        unsigned long val32;

        val32 = inl(smires->start);
        /* Bit 13: TCO_EN     -> 0 = Disables TCO logic generating an SMI#
           Bit  0: GBL_SMI_EN -> 0 = No SMI# will be generated by ICH. */
        val32 &= 0xffffdffe;
        outl(val32, smires->start);
}

static void broken_bios_stop(struct resource *smires)
{
        unsigned long val32;

        val32 = inl(smires->start);
        /* Bit 13: TCO_EN     -> 1 = Enables TCO logic generating an SMI#
           Bit  0: GBL_SMI_EN -> 1 = Turn global SMI on again. */
        val32 |= 0x00002001;
        outl(val32, smires->start);
}

/*
 *      Generic Support Functions
 */

void iTCO_vendor_pre_start(struct resource *smires,
                           unsigned int heartbeat)
{
        switch (vendorsupport) {
        case SUPERMICRO_OLD_BOARD:
                supermicro_old_pre_start(smires);
                break;
        case SUPERMICRO_NEW_BOARD:
                supermicro_new_pre_start(heartbeat);
                break;
        case BROKEN_BIOS:
                broken_bios_start(smires);
                break;
        }
}
EXPORT_SYMBOL(iTCO_vendor_pre_start);

void iTCO_vendor_pre_stop(struct resource *smires)
{
        switch (vendorsupport) {
        case SUPERMICRO_OLD_BOARD:
                supermicro_old_pre_stop(smires);
                break;
        case SUPERMICRO_NEW_BOARD:
                supermicro_new_pre_stop();
                break;
        case BROKEN_BIOS:
                broken_bios_stop(smires);
                break;
        }
}
EXPORT_SYMBOL(iTCO_vendor_pre_stop);

void iTCO_vendor_pre_keepalive(struct resource *smires, unsigned int heartbeat)
{
        if (vendorsupport == SUPERMICRO_NEW_BOARD)
                supermicro_new_pre_set_heartbeat(heartbeat);
}
EXPORT_SYMBOL(iTCO_vendor_pre_keepalive);

void iTCO_vendor_pre_set_heartbeat(unsigned int heartbeat)
{
        if (vendorsupport == SUPERMICRO_NEW_BOARD)
                supermicro_new_pre_set_heartbeat(heartbeat);
}
EXPORT_SYMBOL(iTCO_vendor_pre_set_heartbeat);

int iTCO_vendor_check_noreboot_on(void)
{
        switch (vendorsupport) {
        case SUPERMICRO_OLD_BOARD:
                return 0;
        default:
                return 1;
        }
}
EXPORT_SYMBOL(iTCO_vendor_check_noreboot_on);

static int __init iTCO_vendor_init_module(void)
{
        pr_info("vendor-support=%d\n", vendorsupport);
        return 0;
}

static void __exit iTCO_vendor_exit_module(void)
{
        pr_info("Module Unloaded\n");
}

module_init(iTCO_vendor_init_module);
module_exit(iTCO_vendor_exit_module);

MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>, "
                "R. Seretny <lkpatches@paypc.com>");
MODULE_DESCRIPTION("Intel TCO Vendor Specific WatchDog Timer Driver Support");
MODULE_VERSION(DRV_VERSION);
MODULE_LICENSE("GPL");