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    SubjectRe: [PATCH] Added MIPS RM9K watchdog driver
    Hi All,

    Can you all review the following watchdog driver? I want to include
    it in my linux-2.6-watchdog-mm tree, but would appreciate it if you
    could have all a look at it again.

    Thomas: I moved start and stop code into seperate functions. I also
    deleted the #include <rm9k_wdt.h> because the file doesn't exist.
    Note that the shutdown function of the platform_device_driver is
    similar to a reboot notifier.

    Thanks in advance,
    Wim.

    --------------------------------------------------------------------------------
    /*
    * 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>


    #define CLOCK 125000000
    #define MAX_TIMEOUT_SECONDS 32
    #define CPCCR 0x0080
    #define CPGIG1SR 0x0044
    #define CPGIG1ER 0x0054



    /* Function prototypes */
    static int __init wdt_gpi_probe(struct device *);
    static int __exit wdt_gpi_remove(struct device *);
    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 const struct resource *wdt_gpi_get_resource(struct platform_device *, const char *, unsigned int);
    static int wdt_gpi_notify(struct notifier_block *, unsigned long, void *);
    static irqreturn_t wdt_gpi_irqhdl(int, void *, struct pt_regs *);




    static const char wdt_gpi_name[] = "wdt_gpi";
    static atomic_t opencnt;
    static int expect_close;
    static int locked = 0;



    /* 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);
    static unsigned long resetaddr = 0xbffdc200;
    module_param(resetaddr, ulong, 0444);
    static unsigned long flagaddr = 0xbffdc104;
    module_param(flagaddr, ulong, 0444);
    static int powercycle = 0;
    module_param(powercycle, bool, 0444);

    static int nowayout = WATCHDOG_NOWAYOUT;
    module_param(nowayout, bool, 0444);



    static 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 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 struct notifier_block wdt_gpi_shutdown = {
    .notifier_call = wdt_gpi_notify,
    };



    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;
    }


    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();
    }



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

    if (unlikely(0 > atomic_dec_if_positive(&opencnt)))
    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, SA_SHIRQ | SA_INTERRUPT,
    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 *i, struct file *f)
    {
    if (nowayout) {
    printk(KERN_NOTICE "%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_NOTICE "%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;
    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((void __user *)arg, &wdinfo, size) ?
    -EFAULT : size;
    break;

    case WDIOC_GETSTATUS:
    break;

    case WDIOC_GETBOOTSTATUS:
    stat = (*(volatile char *) flagaddr & 0x01)
    ? WDIOF_CARDRESET : 0;
    res = __copy_to_user((void __user *)arg, &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, (const void __user *) arg,
    size))) {
    res = -EFAULT;
    break;
    }

    if (val > 32)
    val = 32;
    timeout = val;
    wdt_gpi_set_timeout(val);
    res = size;
    printk("%s: timeout set to %u seconds\n",
    wdt_gpi_name, timeout);
    }
    break;

    case WDIOC_GETTIMEOUT:
    res = __copy_to_user((void __user *) arg, &timeout, size) ?
    -EFAULT : size;
    break;
    }

    return res;
    }




    static irqreturn_t wdt_gpi_irqhdl(int irq, void *ctxt, struct pt_regs *regs)
    {
    if (!unlikely(__raw_readl(wd_regs + 0x0008) & 0x1))
    return IRQ_NONE;
    __raw_writel(0x1, wd_regs + 0x0008);


    printk(KERN_WARNING "%s: watchdog expired - resetting system\n",
    wdt_gpi_name);

    *(volatile char *) flagaddr |= 0x01;
    *(volatile char *) resetaddr = powercycle ? 0x01 : 0x2;
    iob();
    while (1)
    cpu_relax();
    }



    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;
    }



    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);
    MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
    MODULE_PARM_DESC(resetaddr, "Address to write to to force a reset");
    MODULE_PARM_DESC(flagaddr, "Address to write to boot flags to");
    MODULE_PARM_DESC(nowayout, "Watchdog cannot be disabled once started");
    MODULE_PARM_DESC(powercycle, "Cycle power if watchdog expires");
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