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/*

 *  Watchdog implementation for GPI h/w found on PMC-Sierra RM9xxx

 *  chips.

 *

 *  Copyright (C) 2004 by Basler Vision Technologies AG

 *  Author: Thomas Koeller <thomas.koeller@baslerweb.com>

 *

 *  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.

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with this program; if not, write to the Free Software

 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

#include <linux/platform_device.h>

#include <linux/module.h>

#include <linux/moduleparam.h>

#include <linux/interrupt.h>

#include <linux/fs.h>

#include <linux/reboot.h>

#include <linux/notifier.h>

#include <linux/miscdevice.h>

#include <linux/watchdog.h>

#include <asm/io.h>

#include <asm/atomic.h>

#include <asm/processor.h>

#include <asm/uaccess.h>

#include <asm/system.h>

#include <asm/rm9k-ocd.h>

#include <rm9k_wdt.h>

#define CLOCK                  125000000

#define MAX_TIMEOUT_SECONDS    32

#define CPCCR                  0x0080

#define CPGIG1SR               0x0044

#define CPGIG1ER               0x0054

/* Function prototypes */

static irqreturn_t wdt_gpi_irqhdl(int, void *);

static void wdt_gpi_start(void);

static void wdt_gpi_stop(void);

static void wdt_gpi_set_timeout(unsigned int);

static int wdt_gpi_open(struct inode *, struct file *);

static int wdt_gpi_release(struct inode *, struct file *);

static ssize_t wdt_gpi_write(struct file *, const char __user *, size_t, loff_t *);

static long wdt_gpi_ioctl(struct file *, unsigned int, unsigned long);

static int wdt_gpi_notify(struct notifier_block *, unsigned long, void *);

static const struct resource *wdt_gpi_get_resource(struct platform_device *, const char *, unsigned int);

static int __init wdt_gpi_probe(struct device *);

static int __exit wdt_gpi_remove(struct device *);

static const char wdt_gpi_name[] = "wdt_gpi";

static atomic_t opencnt;

static int expect_close;

static int locked;

/* These are set from device resources */

static void __iomem * wd_regs;

static unsigned int wd_irq, wd_ctr;

/* Module arguments */

static int timeout = MAX_TIMEOUT_SECONDS;

module_param(timeout, int, 0444);

MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");

static unsigned long resetaddr = 0xbffdc200;

module_param(resetaddr, ulong, 0444);

MODULE_PARM_DESC(resetaddr, "Address to write to to force a reset");

static unsigned long flagaddr = 0xbffdc104;

module_param(flagaddr, ulong, 0444);

MODULE_PARM_DESC(flagaddr, "Address to write to boot flags to");

static int powercycle;

module_param(powercycle, bool, 0444);

MODULE_PARM_DESC(powercycle, "Cycle power if watchdog expires");

static int nowayout = WATCHDOG_NOWAYOUT;

module_param(nowayout, bool, 0444);

MODULE_PARM_DESC(nowayout, "Watchdog cannot be disabled once started");

/* Kernel interfaces */

static const struct file_operations fops = {

        .owner          = THIS_MODULE,

        .open           = wdt_gpi_open,

        .release        = wdt_gpi_release,

        .write          = wdt_gpi_write,

        .unlocked_ioctl = wdt_gpi_ioctl,

};

static struct miscdevice miscdev = {

        .minor          = WATCHDOG_MINOR,

        .name           = wdt_gpi_name,

        .fops           = &fops,

};

static struct notifier_block wdt_gpi_shutdown = {

        .notifier_call  = wdt_gpi_notify,

};

/* Interrupt handler */

static irqreturn_t wdt_gpi_irqhdl(int irq, void *ctxt)

{

        if (!unlikely(__raw_readl(wd_regs + 0x0008) & 0x1))

                return IRQ_NONE;

        __raw_writel(0x1, wd_regs + 0x0008);

        printk(KERN_CRIT "%s: watchdog expired - resetting system\n",

                wdt_gpi_name);

        *(volatile char *) flagaddr |= 0x01;

        *(volatile char *) resetaddr = powercycle ? 0x01 : 0x2;

        iob();

        while (1)

                cpu_relax();

}

/* Watchdog functions */

static void wdt_gpi_start(void)

{

        u32 reg;

        lock_titan_regs();

        reg = titan_readl(CPGIG1ER);

        titan_writel(reg | (0x100 << wd_ctr), CPGIG1ER);

        iob();

        unlock_titan_regs();

}

static void wdt_gpi_stop(void)

{

        u32 reg;

        lock_titan_regs();

        reg = titan_readl(CPCCR) & ~(0xf << (wd_ctr * 4));

        titan_writel(reg, CPCCR);

        reg = titan_readl(CPGIG1ER);

        titan_writel(reg & ~(0x100 << wd_ctr), CPGIG1ER);

        iob();

        unlock_titan_regs();

}

static void wdt_gpi_set_timeout(unsigned int to)

{

        u32 reg;

        const u32 wdval = (to * CLOCK) & ~0x0000000f;

        lock_titan_regs();

        reg = titan_readl(CPCCR) & ~(0xf << (wd_ctr * 4));

        titan_writel(reg, CPCCR);

        wmb();

        __raw_writel(wdval, wd_regs + 0x0000);

        wmb();

        titan_writel(reg | (0x2 << (wd_ctr * 4)), CPCCR);

        wmb();

        titan_writel(reg | (0x5 << (wd_ctr * 4)), CPCCR);

        iob();

        unlock_titan_regs();

}

/* /dev/watchdog operations */

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

{

        int res;

        if (unlikely(atomic_dec_if_positive(&opencnt) < 0))

                return -EBUSY;

        expect_close = 0;

        if (locked) {

                module_put(THIS_MODULE);

                free_irq(wd_irq, &miscdev);

                locked = 0;

        }

        res = request_irq(wd_irq, wdt_gpi_irqhdl, IRQF_SHARED | IRQF_DISABLED,

                          wdt_gpi_name, &miscdev);

        if (unlikely(res))

                return res;

        wdt_gpi_set_timeout(timeout);

        wdt_gpi_start();

        printk(KERN_INFO "%s: watchdog started, timeout = %u seconds\n",

                wdt_gpi_name, timeout);

        return nonseekable_open(inode, file);

}

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

{

        if (nowayout) {

                printk(KERN_INFO "%s: no way out - watchdog left running\n",

                        wdt_gpi_name);

                __module_get(THIS_MODULE);

                locked = 1;

        } else {

                if (expect_close) {

                        wdt_gpi_stop();

                        free_irq(wd_irq, &miscdev);

                        printk(KERN_INFO "%s: watchdog stopped\n", wdt_gpi_name);

                } else {

                        printk(KERN_CRIT "%s: unexpected close() -"

                                " watchdog left running\n",

                                wdt_gpi_name);

                        wdt_gpi_set_timeout(timeout);

                        __module_get(THIS_MODULE);

                        locked = 1;

                }

        }

        atomic_inc(&opencnt);

        return 0;

}

static ssize_t

wdt_gpi_write(struct file *f, const char __user *d, size_t s, loff_t *o)

{

        char val;

        wdt_gpi_set_timeout(timeout);

        expect_close = (s > 0) && !get_user(val, d) && (val == 'V');

        return s ? 1 : 0;

}

static long

wdt_gpi_ioctl(struct file *f, unsigned int cmd, unsigned long arg)

{

        long res = -ENOTTY;

        const long size = _IOC_SIZE(cmd);

        int stat;

        void __user *argp = (void __user *)arg;

        static struct watchdog_info wdinfo = {

                .identity               = "RM9xxx/GPI watchdog",

                .firmware_version       = 0,

                .options                = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING

        };

        if (unlikely(_IOC_TYPE(cmd) != WATCHDOG_IOCTL_BASE))

                return -ENOTTY;

        if ((_IOC_DIR(cmd) & _IOC_READ)

            && !access_ok(VERIFY_WRITE, arg, size))

                return -EFAULT;

        if ((_IOC_DIR(cmd) & _IOC_WRITE)

            && !access_ok(VERIFY_READ, arg, size))

                return -EFAULT;

        expect_close = 0;

        switch (cmd) {

        case WDIOC_GETSUPPORT:

                wdinfo.options = nowayout ?

                        WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING :

                        WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE;

                res = __copy_to_user(argp, &wdinfo, size) ?  -EFAULT : size;

                break;

        case WDIOC_GETSTATUS:

                break;

        case WDIOC_GETBOOTSTATUS:

                stat = (*(volatile char *) flagaddr & 0x01)

                        ? WDIOF_CARDRESET : 0;

                res = __copy_to_user(argp, &stat, size) ?

                        -EFAULT : size;

                break;

        case WDIOC_SETOPTIONS:

                break;

        case WDIOC_KEEPALIVE:

                wdt_gpi_set_timeout(timeout);

                res = size;

                break;

        case WDIOC_SETTIMEOUT:

                {

                        int val;

                        if (unlikely(__copy_from_user(&val, argp, size))) {

                                res = -EFAULT;

                                break;

                        }

                        if (val > MAX_TIMEOUT_SECONDS)

                                val = MAX_TIMEOUT_SECONDS;

                        timeout = val;

                        wdt_gpi_set_timeout(val);

                        res = size;

                        printk(KERN_INFO "%s: timeout set to %u seconds\n",

                                wdt_gpi_name, timeout);

                }

                break;

        case WDIOC_GETTIMEOUT:

                res = __copy_to_user(argp, &timeout, size) ?

                        -EFAULT : size;

                break;

        }

        return res;

}

/* Shutdown notifier */

static int

wdt_gpi_notify(struct notifier_block *this, unsigned long code, void *unused)

{

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

                wdt_gpi_stop();

        return NOTIFY_DONE;

}

/* Init & exit procedures */

static const struct resource *

wdt_gpi_get_resource(struct platform_device *pdv, const char *name,

                      unsigned int type)

{

        char buf[80];

        if (snprintf(buf, sizeof buf, "%s_0", name) >= sizeof buf)

                return NULL;

        return platform_get_resource_byname(pdv, type, buf);

}

/* No hotplugging on the platform bus - use __init */

static int __init wdt_gpi_probe(struct device *dev)

{

        int res;

        struct platform_device * const pdv = to_platform_device(dev);

        const struct resource

                * const rr = wdt_gpi_get_resource(pdv, WDT_RESOURCE_REGS,

                                                  IORESOURCE_MEM),

                * const ri = wdt_gpi_get_resource(pdv, WDT_RESOURCE_IRQ,

                                                  IORESOURCE_IRQ),

                * const rc = wdt_gpi_get_resource(pdv, WDT_RESOURCE_COUNTER,

                                                  0);

        if (unlikely(!rr || !ri || !rc))

                return -ENXIO;

        wd_regs = ioremap_nocache(rr->start, rr->end + 1 - rr->start);

        if (unlikely(!wd_regs))

                return -ENOMEM;

        wd_irq = ri->start;

        wd_ctr = rc->start;

        res = misc_register(&miscdev);

        if (res)

                iounmap(wd_regs);

        else

                register_reboot_notifier(&wdt_gpi_shutdown);

        return res;

}

static int __exit wdt_gpi_remove(struct device *dev)

{

        int res;

        unregister_reboot_notifier(&wdt_gpi_shutdown);

        res = misc_deregister(&miscdev);

        iounmap(wd_regs);

        wd_regs = NULL;

        return res;

}

/* Device driver init & exit */

static struct device_driver wdt_gpi_driver = {

        .name           = (char *) wdt_gpi_name,

        .bus            = &platform_bus_type,

        .owner          = THIS_MODULE,

        .probe          = wdt_gpi_probe,

        .remove         = __exit_p(wdt_gpi_remove),

        .shutdown       = NULL,

        .suspend        = NULL,

        .resume         = NULL,

};

static int __init wdt_gpi_init_module(void)

{

        atomic_set(&opencnt, 1);

        if (timeout > MAX_TIMEOUT_SECONDS)

                timeout = MAX_TIMEOUT_SECONDS;

        return driver_register(&wdt_gpi_driver);

}

static void __exit wdt_gpi_cleanup_module(void)

{

        driver_unregister(&wdt_gpi_driver);

}

module_init(wdt_gpi_init_module);

module_exit(wdt_gpi_cleanup_module);

MODULE_AUTHOR("Thomas Koeller <thomas.koeller@baslerweb.com>");

MODULE_DESCRIPTION("Basler eXcite watchdog driver for gpi devices");

MODULE_VERSION("0.1");

MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);