/*
 *      sch311x_wdt.c - Driver for the SCH311x Super-I/O chips
 *                      integrated watchdog.
 *
 *      (c) Copyright 2008 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

/* 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/... */
#include <linux/miscdevice.h>           /* For struct miscdevice */
#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/ioport.h>               /* For io-port access */
#include <linux/spinlock.h>             /* For spin_lock/spin_unlock/... */
#include <linux/uaccess.h>              /* For copy_to_user/put_user/... */
#include <linux/io.h>                   /* For inb/outb/... */

/* Module and version information */
#define DRV_NAME        "sch311x_wdt"

/* Runtime registers */
#define GP60                    0x47
#define WDT_TIME_OUT            0x65
#define WDT_VAL                 0x66
#define WDT_CFG                 0x67
#define WDT_CTRL                0x68

/* internal variables */
static unsigned long sch311x_wdt_is_open;
static char sch311x_wdt_expect_close;
static struct platform_device *sch311x_wdt_pdev;

static int sch311x_ioports[] = { 0x2e, 0x4e, 0x162e, 0x164e, 0x00 };

static struct { /* The devices private data */
        /* the Runtime Register base address */
        unsigned short runtime_reg;
        /* The card's boot status */
        int boot_status;
        /* the lock for io operations */
        spinlock_t io_lock;
} sch311x_wdt_data;

/* Module load parameters */
static unsigned short force_id;
module_param(force_id, ushort, 0);
MODULE_PARM_DESC(force_id, "Override the detected device ID");

#define WATCHDOG_TIMEOUT 60             /* 60 sec default timeout */
static int timeout = WATCHDOG_TIMEOUT;  /* in seconds */
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
        "Watchdog timeout in seconds. 1<= timeout <=15300, 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) ")");

/*
 *      Super-IO functions
 */

static inline void sch311x_sio_enter(int sio_config_port)
{
        outb(0x55, sio_config_port);
}

static inline void sch311x_sio_exit(int sio_config_port)
{
        outb(0xaa, sio_config_port);
}

static inline int sch311x_sio_inb(int sio_config_port, int reg)
{
        outb(reg, sio_config_port);
        return inb(sio_config_port + 1);
}

static inline void sch311x_sio_outb(int sio_config_port, int reg, int val)
{
        outb(reg, sio_config_port);
        outb(val, sio_config_port + 1);
}

/*
 *      Watchdog Operations
 */

static void sch311x_wdt_set_timeout(int t)
{
        unsigned char timeout_unit = 0x80;

        /* When new timeout is bigger then 255 seconds, we will use minutes */
        if (t > 255) {
                timeout_unit = 0;
                t /= 60;
        }

        /* -- Watchdog Timeout --
         * Bit 0-6 (Reserved)
         * Bit 7   WDT Time-out Value Units Select
         *         (0 = Minutes, 1 = Seconds)
         */
        outb(timeout_unit, sch311x_wdt_data.runtime_reg + WDT_TIME_OUT);

        /* -- Watchdog Timer Time-out Value --
         * Bit 0-7 Binary coded units (0=Disabled, 1..255)
         */
        outb(t, sch311x_wdt_data.runtime_reg + WDT_VAL);
}

static void sch311x_wdt_start(void)
{
        unsigned char t;

        spin_lock(&sch311x_wdt_data.io_lock);

        /* set watchdog's timeout */
        sch311x_wdt_set_timeout(timeout);
        /* enable the watchdog */
        /* -- General Purpose I/O Bit 6.0 --
         * Bit 0,   In/Out: 0 = Output, 1 = Input
         * Bit 1,   Polarity: 0 = No Invert, 1 = Invert
         * Bit 2-3, Function select: 00 = GPI/O, 01 = LED1, 11 = WDT,
         *                           10 = Either Edge Triggered Intr.4
         * Bit 4-6  (Reserved)
         * Bit 7,   Output Type: 0 = Push Pull Bit, 1 = Open Drain
         */
        t = inb(sch311x_wdt_data.runtime_reg + GP60);
        outb((t & ~0x0d) | 0x0c, sch311x_wdt_data.runtime_reg + GP60);

        spin_unlock(&sch311x_wdt_data.io_lock);

}

static void sch311x_wdt_stop(void)
{
        unsigned char t;

        spin_lock(&sch311x_wdt_data.io_lock);

        /* stop the watchdog */
        t = inb(sch311x_wdt_data.runtime_reg + GP60);
        outb((t & ~0x0d) | 0x01, sch311x_wdt_data.runtime_reg + GP60);
        /* disable timeout by setting it to 0 */
        sch311x_wdt_set_timeout(0);

        spin_unlock(&sch311x_wdt_data.io_lock);
}

static void sch311x_wdt_keepalive(void)
{
        spin_lock(&sch311x_wdt_data.io_lock);
        sch311x_wdt_set_timeout(timeout);
        spin_unlock(&sch311x_wdt_data.io_lock);
}

static int sch311x_wdt_set_heartbeat(int t)
{
        if (t < 1 || t > (255*60))
                return -EINVAL;

        /* When new timeout is bigger then 255 seconds,
         * we will round up to minutes (with a max of 255) */
        if (t > 255)
                t = (((t - 1) / 60) + 1) * 60;

        timeout = t;
        return 0;
}

static void sch311x_wdt_get_status(int *status)
{
        unsigned char new_status;

        *status = 0;

        spin_lock(&sch311x_wdt_data.io_lock);

        /* -- Watchdog timer control --
         * Bit 0   Status Bit: 0 = Timer counting, 1 = Timeout occurred
         * Bit 1   Reserved
         * Bit 2   Force Timeout: 1 = Forces WD timeout event (self-cleaning)
         * Bit 3   P20 Force Timeout enabled:
         *          0 = P20 activity does not generate the WD timeout event
         *          1 = P20 Allows rising edge of P20, from the keyboard
         *              controller, to force the WD timeout event.
         * Bit 4-7 Reserved
         */
        new_status = inb(sch311x_wdt_data.runtime_reg + WDT_CTRL);
        if (new_status & 0x01)
                *status |= WDIOF_CARDRESET;

        spin_unlock(&sch311x_wdt_data.io_lock);
}

/*
 *      /dev/watchdog handling
 */

static ssize_t sch311x_wdt_write(struct file *file, const char __user *buf,
                                                size_t count, loff_t *ppos)
{
        if (count) {
                if (!nowayout) {
                        size_t i;

                        sch311x_wdt_expect_close = 0;

                        for (i = 0; i != count; i++) {
                                char c;
                                if (get_user(c, buf + i))
                                        return -EFAULT;
                                if (c == 'V')
                                        sch311x_wdt_expect_close = 42;
                        }
                }
                sch311x_wdt_keepalive();
        }
        return count;
}

static long sch311x_wdt_ioctl(struct file *file, unsigned int cmd,
                                                        unsigned long arg)
{
        int status;
        int new_timeout;
        void __user *argp = (void __user *)arg;
        int __user *p = argp;
        static const struct watchdog_info ident = {
                .options                = WDIOF_KEEPALIVEPING |
                                          WDIOF_SETTIMEOUT |
                                          WDIOF_MAGICCLOSE,
                .firmware_version       = 1,
                .identity               = DRV_NAME,
        };

        switch (cmd) {
        case WDIOC_GETSUPPORT:
                if (copy_to_user(argp, &ident, sizeof(ident)))
                        return -EFAULT;
                break;

        case WDIOC_GETSTATUS:
        {
                sch311x_wdt_get_status(&status);
                return put_user(status, p);
        }
        case WDIOC_GETBOOTSTATUS:
                return put_user(sch311x_wdt_data.boot_status, p);

        case WDIOC_SETOPTIONS:
        {
                int options, retval = -EINVAL;

                if (get_user(options, p))
                        return -EFAULT;
                if (options & WDIOS_DISABLECARD) {
                        sch311x_wdt_stop();
                        retval = 0;
                }
                if (options & WDIOS_ENABLECARD) {
                        sch311x_wdt_start();
                        retval = 0;
                }
                return retval;
        }
        case WDIOC_KEEPALIVE:
                sch311x_wdt_keepalive();
                break;

        case WDIOC_SETTIMEOUT:
                if (get_user(new_timeout, p))
                        return -EFAULT;
                if (sch311x_wdt_set_heartbeat(new_timeout))
                        return -EINVAL;
                sch311x_wdt_keepalive();
                /* Fall */
        case WDIOC_GETTIMEOUT:
                return put_user(timeout, p);
        default:
                return -ENOTTY;
        }
        return 0;
}

static int sch311x_wdt_open(struct inode *inode, struct file *file)
{
        if (test_and_set_bit(0, &sch311x_wdt_is_open))
                return -EBUSY;
        /*
         *      Activate
         */
        sch311x_wdt_start();
        return nonseekable_open(inode, file);
}

static int sch311x_wdt_close(struct inode *inode, struct file *file)
{
        if (sch311x_wdt_expect_close == 42) {
                sch311x_wdt_stop();
        } else {
                pr_crit("Unexpected close, not stopping watchdog!\n");
                sch311x_wdt_keepalive();
        }
        clear_bit(0, &sch311x_wdt_is_open);
        sch311x_wdt_expect_close = 0;
        return 0;
}

/*
 *      Kernel Interfaces
 */

static const struct file_operations sch311x_wdt_fops = {
        .owner          = THIS_MODULE,
        .llseek         = no_llseek,
        .write          = sch311x_wdt_write,
        .unlocked_ioctl = sch311x_wdt_ioctl,
        .open           = sch311x_wdt_open,
        .release        = sch311x_wdt_close,
};

static struct miscdevice sch311x_wdt_miscdev = {
        .minor  = WATCHDOG_MINOR,
        .name   = "watchdog",
        .fops   = &sch311x_wdt_fops,
};

/*
 *      Init & exit routines
 */

static int sch311x_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        int err;

        spin_lock_init(&sch311x_wdt_data.io_lock);

        if (!request_region(sch311x_wdt_data.runtime_reg + GP60, 1, DRV_NAME)) {
                dev_err(dev, "Failed to request region 0x%04x-0x%04x.\n",
                        sch311x_wdt_data.runtime_reg + GP60,
                        sch311x_wdt_data.runtime_reg + GP60);
                err = -EBUSY;
                goto exit;
        }

        if (!request_region(sch311x_wdt_data.runtime_reg + WDT_TIME_OUT, 4,
                                                                DRV_NAME)) {
                dev_err(dev, "Failed to request region 0x%04x-0x%04x.\n",
                        sch311x_wdt_data.runtime_reg + WDT_TIME_OUT,
                        sch311x_wdt_data.runtime_reg + WDT_CTRL);
                err = -EBUSY;
                goto exit_release_region;
        }

        /* Make sure that the watchdog is not running */
        sch311x_wdt_stop();

        /* Disable keyboard and mouse interaction and interrupt */
        /* -- Watchdog timer configuration --
         * Bit 0   Reserved
         * Bit 1   Keyboard enable: 0* = No Reset, 1 = Reset WDT upon KBD Intr.
         * Bit 2   Mouse enable: 0* = No Reset, 1 = Reset WDT upon Mouse Intr
         * Bit 3   Reserved
         * Bit 4-7 WDT Interrupt Mapping: (0000* = Disabled,
         *            0001=IRQ1, 0010=(Invalid), 0011=IRQ3 to 1111=IRQ15)
         */
        outb(0, sch311x_wdt_data.runtime_reg + WDT_CFG);

        /* Check that the heartbeat value is within it's range ;
         * if not reset to the default */
        if (sch311x_wdt_set_heartbeat(timeout)) {
                sch311x_wdt_set_heartbeat(WATCHDOG_TIMEOUT);
                dev_info(dev, "timeout value must be 1<=x<=15300, using %d\n",
                        timeout);
        }

        /* Get status at boot */
        sch311x_wdt_get_status(&sch311x_wdt_data.boot_status);

        sch311x_wdt_miscdev.parent = dev;

        err = misc_register(&sch311x_wdt_miscdev);
        if (err != 0) {
                dev_err(dev, "cannot register miscdev on minor=%d (err=%d)\n",
                                                        WATCHDOG_MINOR, err);
                goto exit_release_region2;
        }

        dev_info(dev,
                "SMSC SCH311x WDT initialized. timeout=%d sec (nowayout=%d)\n",
                timeout, nowayout);

        return 0;

exit_release_region2:
        release_region(sch311x_wdt_data.runtime_reg + WDT_TIME_OUT, 4);
exit_release_region:
        release_region(sch311x_wdt_data.runtime_reg + GP60, 1);
        sch311x_wdt_data.runtime_reg = 0;
exit:
        return err;
}

static int sch311x_wdt_remove(struct platform_device *pdev)
{
        /* Stop the timer before we leave */
        if (!nowayout)
                sch311x_wdt_stop();

        /* Deregister */
        misc_deregister(&sch311x_wdt_miscdev);
        release_region(sch311x_wdt_data.runtime_reg + WDT_TIME_OUT, 4);
        release_region(sch311x_wdt_data.runtime_reg + GP60, 1);
        sch311x_wdt_data.runtime_reg = 0;
        return 0;
}

static void sch311x_wdt_shutdown(struct platform_device *dev)
{
        /* Turn the WDT off if we have a soft shutdown */
        sch311x_wdt_stop();
}

static struct platform_driver sch311x_wdt_driver = {
        .probe          = sch311x_wdt_probe,
        .remove         = sch311x_wdt_remove,
        .shutdown       = sch311x_wdt_shutdown,
        .driver         = {
                .name = DRV_NAME,
        },
};

static int __init sch311x_detect(int sio_config_port, unsigned short *addr)
{
        int err = 0, reg;
        unsigned short base_addr;
        unsigned char dev_id;

        sch311x_sio_enter(sio_config_port);

        /* Check device ID. We currently know about:
         * SCH3112 (0x7c), SCH3114 (0x7d), and SCH3116 (0x7f). */
        reg = force_id ? force_id : sch311x_sio_inb(sio_config_port, 0x20);
        if (!(reg == 0x7c || reg == 0x7d || reg == 0x7f)) {
                err = -ENODEV;
                goto exit;
        }
        dev_id = reg == 0x7c ? 2 : reg == 0x7d ? 4 : 6;

        /* Select logical device A (runtime registers) */
        sch311x_sio_outb(sio_config_port, 0x07, 0x0a);

        /* Check if Logical Device Register is currently active */
        if ((sch311x_sio_inb(sio_config_port, 0x30) & 0x01) == 0)
                pr_info("Seems that LDN 0x0a is not active...\n");

        /* Get the base address of the runtime registers */
        base_addr = (sch311x_sio_inb(sio_config_port, 0x60) << 8) |
                           sch311x_sio_inb(sio_config_port, 0x61);
        if (!base_addr) {
                pr_err("Base address not set\n");
                err = -ENODEV;
                goto exit;
        }
        *addr = base_addr;

        pr_info("Found an SMSC SCH311%d chip at 0x%04x\n", dev_id, base_addr);

exit:
        sch311x_sio_exit(sio_config_port);
        return err;
}

static int __init sch311x_wdt_init(void)
{
        int err, i, found = 0;
        unsigned short addr = 0;

        for (i = 0; !found && sch311x_ioports[i]; i++)
                if (sch311x_detect(sch311x_ioports[i], &addr) == 0)
                        found++;

        if (!found)
                return -ENODEV;

        sch311x_wdt_data.runtime_reg = addr;

        err = platform_driver_register(&sch311x_wdt_driver);
        if (err)
                return err;

        sch311x_wdt_pdev = platform_device_register_simple(DRV_NAME, addr,
                                                                NULL, 0);

        if (IS_ERR(sch311x_wdt_pdev)) {
                err = PTR_ERR(sch311x_wdt_pdev);
                goto unreg_platform_driver;
        }

        return 0;

unreg_platform_driver:
        platform_driver_unregister(&sch311x_wdt_driver);
        return err;
}

static void __exit sch311x_wdt_exit(void)
{
        platform_device_unregister(sch311x_wdt_pdev);
        platform_driver_unregister(&sch311x_wdt_driver);
}

module_init(sch311x_wdt_init);
module_exit(sch311x_wdt_exit);

MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
MODULE_DESCRIPTION("SMSC SCH311x WatchDog Timer Driver");
MODULE_LICENSE("GPL");