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/*

 *      NS pc87413-wdt Watchdog Timer driver for Linux 2.6.x.x

 *

 *      This code is based on wdt.c with original copyright.

 *

 *      (C) Copyright 2006 Sven Anders, <anders@anduras.de>

 *                     and Marcus Junker, <junker@anduras.de>

 *

 *      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 Sven Anders, Marcus Junker nor ANDURAS AG

 *      admit liability nor provide warranty for any of this software.

 *      This material is provided "AS-IS" and at no charge.

 *

 *      Release 1.1

 */

#include <linux/module.h>

#include <linux/types.h>

#include <linux/miscdevice.h>

#include <linux/watchdog.h>

#include <linux/ioport.h>

#include <linux/delay.h>

#include <linux/notifier.h>

#include <linux/fs.h>

#include <linux/reboot.h>

#include <linux/init.h>

#include <linux/spinlock.h>

#include <linux/moduleparam.h>

#include <linux/version.h>

#include <asm/io.h>

#include <asm/uaccess.h>

#include <asm/system.h>

/* #define DEBUG 1 */

#define DEFAULT_TIMEOUT     1            /* 1 minute */

#define MAX_TIMEOUT         255

#define VERSION             "1.1"

#define MODNAME             "pc87413 WDT"

#define PFX                 MODNAME ": "

#define DPFX                MODNAME " - DEBUG: "

#define WDT_INDEX_IO_PORT   (io+0)       /* I/O port base (index register) */

#define WDT_DATA_IO_PORT    (WDT_INDEX_IO_PORT+1)

#define SWC_LDN             0x04

#define SIOCFG2             0x22         /* Serial IO register */

#define WDCTL               0x10         /* Watchdog-Timer-Controll-Register */

#define WDTO                0x11         /* Watchdog timeout register */

#define WDCFG               0x12         /* Watchdog config register */

static int io = 0x2E;                    /* Address used on Portwell Boards */

static int timeout = DEFAULT_TIMEOUT;    /* timeout value */

static unsigned long timer_enabled = 0;  /* is the timer enabled? */

static char expect_close;                /* is the close expected? */

static DEFINE_SPINLOCK(io_lock);/* to guard the watchdog from io races */

static int nowayout = WATCHDOG_NOWAYOUT;

/* -- Low level function ----------------------------------------*/

/* Select pins for Watchdog output */

static inline void pc87413_select_wdt_out (void)

{

        unsigned int cr_data = 0;

        /* Step 1: Select multiple pin,pin55,as WDT output */

        outb_p(SIOCFG2, WDT_INDEX_IO_PORT);

        cr_data = inb (WDT_DATA_IO_PORT);

        cr_data |= 0x80; /* Set Bit7 to 1*/

        outb_p(SIOCFG2, WDT_INDEX_IO_PORT);

        outb_p(cr_data, WDT_DATA_IO_PORT);

#ifdef DEBUG

        printk(KERN_INFO DPFX "Select multiple pin,pin55,as WDT output:"

                              " Bit7 to 1: %d\n", cr_data);

#endif

}

/* Enable SWC functions */

static inline void pc87413_enable_swc(void)

{

        unsigned int cr_data=0;

        /* Step 2: Enable SWC functions */

        outb_p(0x07, WDT_INDEX_IO_PORT);        /* Point SWC_LDN (LDN=4) */

        outb_p(SWC_LDN, WDT_DATA_IO_PORT);

        outb_p(0x30, WDT_INDEX_IO_PORT);        /* Read Index 0x30 First */

        cr_data = inb(WDT_DATA_IO_PORT);

        cr_data |= 0x01;                        /* Set Bit0 to 1 */

        outb_p(0x30, WDT_INDEX_IO_PORT);

        outb_p(cr_data, WDT_DATA_IO_PORT);      /* Index0x30_bit0P1 */

#ifdef DEBUG

        printk(KERN_INFO DPFX "pc87413 - Enable SWC functions\n");

#endif

}

/* Read SWC I/O base address */

static inline unsigned int pc87413_get_swc_base(void)

{

        unsigned int  swc_base_addr = 0;

        unsigned char addr_l, addr_h = 0;

        /* Step 3: Read SWC I/O Base Address */

        outb_p(0x60, WDT_INDEX_IO_PORT);        /* Read Index 0x60 */

        addr_h = inb(WDT_DATA_IO_PORT);

        outb_p(0x61, WDT_INDEX_IO_PORT);        /* Read Index 0x61 */

        addr_l = inb(WDT_DATA_IO_PORT);

        swc_base_addr = (addr_h << 8) + addr_l;

#ifdef DEBUG

        printk(KERN_INFO DPFX "Read SWC I/O Base Address: low %d, high %d,"

                              " res %d\n", addr_l, addr_h, swc_base_addr);

#endif

        return swc_base_addr;

}

/* Select Bank 3 of SWC */

static inline void pc87413_swc_bank3(unsigned int swc_base_addr)

{

        /* Step 4: Select Bank3 of SWC */

        outb_p(inb(swc_base_addr + 0x0f) | 0x03, swc_base_addr + 0x0f);

#ifdef DEBUG

        printk(KERN_INFO DPFX "Select Bank3 of SWC\n");

#endif

}

/* Set watchdog timeout to x minutes */

static inline void pc87413_programm_wdto(unsigned int swc_base_addr,

                                         char pc87413_time)

{

        /* Step 5: Programm WDTO, Twd. */

        outb_p(pc87413_time, swc_base_addr + WDTO);

#ifdef DEBUG

        printk(KERN_INFO DPFX "Set WDTO to %d minutes\n", pc87413_time);

#endif

}

/* Enable WDEN */

static inline void pc87413_enable_wden(unsigned int swc_base_addr)

{

        /* Step 6: Enable WDEN */

        outb_p(inb (swc_base_addr + WDCTL) | 0x01, swc_base_addr + WDCTL);

#ifdef DEBUG

        printk(KERN_INFO DPFX "Enable WDEN\n");

#endif

}

/* Enable SW_WD_TREN */

static inline void pc87413_enable_sw_wd_tren(unsigned int swc_base_addr)

{

        /* Enable SW_WD_TREN */

        outb_p(inb (swc_base_addr + WDCFG) | 0x80, swc_base_addr + WDCFG);

#ifdef DEBUG

        printk(KERN_INFO DPFX "Enable SW_WD_TREN\n");

#endif

}

/* Disable SW_WD_TREN */

static inline void pc87413_disable_sw_wd_tren(unsigned int swc_base_addr)

{

        /* Disable SW_WD_TREN */

        outb_p(inb (swc_base_addr + WDCFG) & 0x7f, swc_base_addr + WDCFG);

#ifdef DEBUG

        printk(KERN_INFO DPFX "pc87413 - Disable SW_WD_TREN\n");

#endif

}

/* Enable SW_WD_TRG */

static inline void pc87413_enable_sw_wd_trg(unsigned int swc_base_addr)

{

        /* Enable SW_WD_TRG */

        outb_p(inb (swc_base_addr + WDCTL) | 0x80, swc_base_addr + WDCTL);

#ifdef DEBUG

        printk(KERN_INFO DPFX "pc87413 - Enable SW_WD_TRG\n");

#endif

}

/* Disable SW_WD_TRG */

static inline void pc87413_disable_sw_wd_trg(unsigned int swc_base_addr)

{

        /* Disable SW_WD_TRG */

        outb_p(inb (swc_base_addr + WDCTL) & 0x7f, swc_base_addr + WDCTL);

#ifdef DEBUG

        printk(KERN_INFO DPFX "Disable SW_WD_TRG\n");

#endif

}

/* -- Higher level functions ------------------------------------*/

/* Enable the watchdog */

static void pc87413_enable(void)

{

        unsigned int swc_base_addr;

        spin_lock(&io_lock);

        pc87413_select_wdt_out();

        pc87413_enable_swc();

        swc_base_addr = pc87413_get_swc_base();

        pc87413_swc_bank3(swc_base_addr);

        pc87413_programm_wdto(swc_base_addr, timeout);

        pc87413_enable_wden(swc_base_addr);

        pc87413_enable_sw_wd_tren(swc_base_addr);

        pc87413_enable_sw_wd_trg(swc_base_addr);

        spin_unlock(&io_lock);

}

/* Disable the watchdog */

static void pc87413_disable(void)

{

        unsigned int swc_base_addr;

        spin_lock(&io_lock);

        pc87413_select_wdt_out();

        pc87413_enable_swc();

        swc_base_addr = pc87413_get_swc_base();

        pc87413_swc_bank3(swc_base_addr);

        pc87413_disable_sw_wd_tren(swc_base_addr);

        pc87413_disable_sw_wd_trg(swc_base_addr);

        pc87413_programm_wdto(swc_base_addr, 0);

        spin_unlock(&io_lock);

}

/* Refresh the watchdog */

static void pc87413_refresh(void)

{

        unsigned int swc_base_addr;

        spin_lock(&io_lock);

        pc87413_select_wdt_out();

        pc87413_enable_swc();

        swc_base_addr = pc87413_get_swc_base();

        pc87413_swc_bank3(swc_base_addr);

        pc87413_disable_sw_wd_tren(swc_base_addr);

        pc87413_disable_sw_wd_trg(swc_base_addr);

        pc87413_programm_wdto(swc_base_addr, timeout);

        pc87413_enable_wden(swc_base_addr);

        pc87413_enable_sw_wd_tren(swc_base_addr);

        pc87413_enable_sw_wd_trg(swc_base_addr);

        spin_unlock(&io_lock);

}

/* -- File operations -------------------------------------------*/

/**

 *      pc87413_open:

 *      @inode: inode of device

 *      @file: file handle to device

 *

 */

static int pc87413_open(struct inode *inode, struct file *file)

{

        /* /dev/watchdog can only be opened once */

        if (test_and_set_bit(0, &timer_enabled))

                return -EBUSY;

        if (nowayout)

                __module_get(THIS_MODULE);

        /* Reload and activate timer */

        pc87413_refresh();

        printk(KERN_INFO MODNAME "Watchdog enabled. Timeout set to"

                                 " %d minute(s).\n", timeout);

        return nonseekable_open(inode, file);

}

/**

 *      pc87413_release:

 *      @inode: inode to board

 *      @file: file handle to board

 *

 *      The watchdog has a configurable API. There is a religious dispute

 *      between people who want their watchdog to be able to shut down and

 *      those who want to be sure if the watchdog manager dies the machine

 *      reboots. In the former case we disable the counters, in the latter

 *      case you have to open it again very soon.

 */

static int pc87413_release(struct inode *inode, struct file *file)

{

        /* Shut off the timer. */

        if (expect_close == 42) {

                pc87413_disable();

                printk(KERN_INFO MODNAME "Watchdog disabled,"

                                         " sleeping again...\n");

        } else {

                printk(KERN_CRIT MODNAME "Unexpected close, not stopping"

                                         " watchdog!\n");

                pc87413_refresh();

        }

        clear_bit(0, &timer_enabled);

        expect_close = 0;

        return 0;

}

/**

 *      pc87413_status:

 *

 *      return, if the watchdog is enabled (timeout is set...)

 */

static int pc87413_status(void)

{

          return 0; /* currently not supported */

}

/**

 *      pc87413_write:

 *      @file: file handle to the watchdog

 *      @data: data buffer to write

 *      @len: length in bytes

 *      @ppos: pointer to the position to write. No seeks allowed

 *

 *      A write to a watchdog device is defined as a keepalive signal. Any

 *      write of data will do, as we we don't define content meaning.

 */

static ssize_t pc87413_write(struct file *file, const char __user *data,

                             size_t len, loff_t *ppos)

{

        /* See if we got the magic character 'V' and reload the timer */

        if (len) {

                if (!nowayout) {

                        size_t i;

                        /* reset expect flag */

                        expect_close = 0;

                        /* scan to see whether or not we got the magic character */

                        for (i = 0; i != len; i++) {

                                char c;

                                if (get_user(c, data+i))

                                        return -EFAULT;

                                if (c == 'V')

                                        expect_close = 42;

                        }

                }

                /* someone wrote to us, we should reload the timer */

                pc87413_refresh();

        }

        return len;

}

/**

 *      pc87413_ioctl:

 *      @inode: inode of the device

 *      @file: file handle to the device

 *      @cmd: watchdog command

 *      @arg: argument pointer

 *

 *      The watchdog API defines a common set of functions for all watchdogs

 *      according to their available features. We only actually usefully support

 *      querying capabilities and current status.

 */

static int pc87413_ioctl(struct inode *inode, struct file *file,

                         unsigned int cmd, unsigned long arg)

{

        int new_timeout;

        union {

                struct watchdog_info __user *ident;

                int __user *i;

        } uarg;

        static struct watchdog_info ident = {

                .options          = WDIOF_KEEPALIVEPING |

                                    WDIOF_SETTIMEOUT |

                                    WDIOF_MAGICCLOSE,

                .firmware_version = 1,

                .identity         = "PC87413(HF/F) watchdog"

        };

        uarg.i = (int __user *)arg;

        switch(cmd) {

                default:

                        return -ENOTTY;

                case WDIOC_GETSUPPORT:

                        return copy_to_user(uarg.ident, &ident,

                                sizeof(ident)) ? -EFAULT : 0;

                case WDIOC_GETSTATUS:

                        return put_user(pc87413_status(), uarg.i);

                case WDIOC_GETBOOTSTATUS:

                        return put_user(0, uarg.i);

                case WDIOC_KEEPALIVE:

                        pc87413_refresh();

#ifdef DEBUG

                        printk(KERN_INFO DPFX "keepalive\n");

#endif

                        return 0;

                case WDIOC_SETTIMEOUT:

                        if (get_user(new_timeout, uarg.i))

                                return -EFAULT;

                        // the API states this is given in secs

                        new_timeout /= 60;

                        if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)

                                return -EINVAL;

                        timeout = new_timeout;

                        pc87413_refresh();

                        // fall through and return the new timeout...

                case WDIOC_GETTIMEOUT:

                        new_timeout = timeout * 60;

                        return put_user(new_timeout, uarg.i);

                case WDIOC_SETOPTIONS:

                {

                        int options, retval = -EINVAL;

                        if (get_user(options, uarg.i))

                                return -EFAULT;

                        if (options & WDIOS_DISABLECARD) {

                                pc87413_disable();

                                retval = 0;

                        }

                        if (options & WDIOS_ENABLECARD) {

                                pc87413_enable();

                                retval = 0;

                        }

                        return retval;

                }

        }

}

/* -- Notifier funtions -----------------------------------------*/

/**

 *      notify_sys:

 *      @this: our notifier block

 *      @code: the event being reported

 *      @unused: unused

 *

 *      Our notifier is called on system shutdowns. We want to turn the card

 *      off at reboot otherwise the machine will reboot again during memory

 *      test or worse yet during the following fsck. This would suck, in fact

 *      trust me - if it happens it does suck.

 */

static int pc87413_notify_sys(struct notifier_block *this,

                              unsigned long code,

                              void *unused)

{

        if (code == SYS_DOWN || code == SYS_HALT)

        {

                /* Turn the card off */

                pc87413_disable();

        }

        return NOTIFY_DONE;

}

/* -- Module's structures ---------------------------------------*/

static const struct file_operations pc87413_fops = {

        .owner          = THIS_MODULE,

        .llseek         = no_llseek,

        .write          = pc87413_write,

        .ioctl          = pc87413_ioctl,

        .open           = pc87413_open,

        .release        = pc87413_release,

};

static struct notifier_block pc87413_notifier =

{

        .notifier_call  = pc87413_notify_sys,

};

static struct miscdevice pc87413_miscdev=

{

        .minor          = WATCHDOG_MINOR,

        .name           = "watchdog",

        .fops           = &pc87413_fops

};

/* -- Module init functions -------------------------------------*/

/**

 *      pc87413_init: module's "constructor"

 *

 *      Set up the WDT watchdog board. All we have to do is grab the

 *      resources we require and bitch if anyone beat us to them.

 *      The open() function will actually kick the board off.

 */

static int __init pc87413_init(void)

{

        int ret;

        printk(KERN_INFO PFX "Version " VERSION " at io 0x%X\n", WDT_INDEX_IO_PORT);

        /* request_region(io, 2, "pc87413"); */

        ret = register_reboot_notifier(&pc87413_notifier);

        if (ret != 0) {

                printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",

                        ret);

        }

        ret = misc_register(&pc87413_miscdev);

        if (ret != 0) {

                printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",

                        WATCHDOG_MINOR, ret);

                unregister_reboot_notifier(&pc87413_notifier);

                return ret;

        }

        printk(KERN_INFO PFX "initialized. timeout=%d min \n", timeout);

        pc87413_enable();

        return 0;

}

/**

 *      pc87413_exit: module's "destructor"

 *

 *      Unload the watchdog. You cannot do this with any file handles open.

 *      If your watchdog is set to continue ticking on close and you unload

 *      it, well it keeps ticking. We won't get the interrupt but the board

 *      will not touch PC memory so all is fine. You just have to load a new

 *      module in 60 seconds or reboot.

 */

static void __exit pc87413_exit(void)

{

        /* Stop the timer before we leave */

        if (!nowayout)

        {

                pc87413_disable();

                printk(KERN_INFO MODNAME "Watchdog disabled.\n");

        }

        misc_deregister(&pc87413_miscdev);

        unregister_reboot_notifier(&pc87413_notifier);

        /* release_region(io,2); */

        printk(MODNAME " watchdog component driver removed.\n");

}

module_init(pc87413_init);

module_exit(pc87413_exit);

MODULE_AUTHOR("Sven Anders <anders@anduras.de>, Marcus Junker <junker@anduras.de>,");

MODULE_DESCRIPTION("PC87413 WDT driver");

MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

module_param(io, int, 0);

MODULE_PARM_DESC(io, MODNAME " I/O port (default: " __MODULE_STRING(io) ").");

module_param(timeout, int, 0);

MODULE_PARM_DESC(timeout, "Watchdog timeout in minutes (default=" __MODULE_STRING(timeout) ").");

module_param(nowayout, int, 0);

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