cpwd.c

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/* cpwd.c - driver implementation for hardware watchdog
 * timers found on Sun Microsystems CP1400 and CP1500 boards.
 *
 * This device supports both the generic Linux watchdog
 * interface and Solaris-compatible ioctls as best it is
 * able.
 *
 * NOTE:    CP1400 systems appear to have a defective intr_mask
 *          register on the PLD, preventing the disabling of
 *          timer interrupts.  We use a timer to periodically
 *          reset 'stopped' watchdogs on affected platforms.
 *
 * Copyright (c) 2000 Eric Brower ([email protected])
 * Copyright (C) 2008 David S. Miller <[email protected]>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/major.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/uaccess.h>

#include <asm/irq.h>
#include <asm/watchdog.h>

#define DRIVER_NAME "cpwd"

#define WD_OBPNAME  "watchdog"
#define WD_BADMODEL "SUNW,501-5336"
#define WD_BTIMEOUT (jiffies + (HZ * 1000))
#define WD_BLIMIT   0xFFFF

#define WD0_MINOR   212
#define WD1_MINOR   213
#define WD2_MINOR   214

/* Internal driver definitions.  */
#define WD0_ID          0
#define WD1_ID          1
#define WD2_ID          2
#define WD_NUMDEVS      3

#define WD_INTR_OFF     0
#define WD_INTR_ON      1

#define WD_STAT_INIT    0x01    /* Watchdog timer is initialized    */
#define WD_STAT_BSTOP   0x02    /* Watchdog timer is brokenstopped  */
#define WD_STAT_SVCD    0x04    /* Watchdog interrupt occurred      */

/* Register value definitions
 */
#define WD0_INTR_MASK   0x01    /* Watchdog device interrupt masks  */
#define WD1_INTR_MASK   0x02
#define WD2_INTR_MASK   0x04

#define WD_S_RUNNING    0x01    /* Watchdog device status running   */
#define WD_S_EXPIRED    0x02    /* Watchdog device status expired   */

struct cpwd {
    void __iomem    *regs;
    spinlock_t  lock;

    unsigned int    irq;

    unsigned long   timeout;
    bool        enabled;
    bool        reboot;
    bool        broken;
    bool        initialized;

    struct {
        struct miscdevice   misc;
        void __iomem        *regs;
        u8          intr_mask;
        u8          runstatus;
        u16         timeout;
    } devs[WD_NUMDEVS];
};

static DEFINE_MUTEX(cpwd_mutex);
static struct cpwd *cpwd_device;

/* Sun uses Altera PLD EPF8820ATC144-4
 * providing three hardware watchdogs:
 *
 * 1) RIC - sends an interrupt when triggered
 * 2) XIR - asserts XIR_B_RESET when triggered, resets CPU
 * 3) POR - asserts POR_B_RESET when triggered, resets CPU, backplane, board
 *
 *** Timer register block definition (struct wd_timer_regblk)
 *
 * dcntr and limit registers (halfword access):
 * -------------------
 * | 15 | ...| 1 | 0 |
 * -------------------
 * |-  counter val  -|
 * -------------------
 * dcntr -  Current 16-bit downcounter value.
 *          When downcounter reaches '0' watchdog expires.
 *          Reading this register resets downcounter with
 *          'limit' value.
 * limit -  16-bit countdown value in 1/10th second increments.
 *          Writing this register begins countdown with input value.
 *          Reading from this register does not affect counter.
 * NOTES:   After watchdog reset, dcntr and limit contain '1'
 *
 * status register (byte access):
 * ---------------------------
 * | 7 | ... | 2 |  1  |  0  |
 * --------------+------------
 * |-   UNUSED  -| EXP | RUN |
 * ---------------------------
 * status-  Bit 0 - Watchdog is running
 *          Bit 1 - Watchdog has expired
 *
 *** PLD register block definition (struct wd_pld_regblk)
 *
 * intr_mask register (byte access):
 * ---------------------------------
 * | 7 | ... | 3 |  2  |  1  |  0  |
 * +-------------+------------------
 * |-   UNUSED  -| WD3 | WD2 | WD1 |
 * ---------------------------------
 * WD3 -  1 == Interrupt disabled for watchdog 3
 * WD2 -  1 == Interrupt disabled for watchdog 2
 * WD1 -  1 == Interrupt disabled for watchdog 1
 *
 * pld_status register (byte access):
 * UNKNOWN, MAGICAL MYSTERY REGISTER
 *
 */
#define WD_TIMER_REGSZ  16
#define WD0_OFF     0
#define WD1_OFF     (WD_TIMER_REGSZ * 1)
#define WD2_OFF     (WD_TIMER_REGSZ * 2)
#define PLD_OFF     (WD_TIMER_REGSZ * 3)

#define WD_DCNTR    0x00
#define WD_LIMIT    0x04
#define WD_STATUS   0x08

#define PLD_IMASK   (PLD_OFF + 0x00)
#define PLD_STATUS  (PLD_OFF + 0x04)

static struct timer_list cpwd_timer;

static int wd0_timeout;
static int wd1_timeout;
static int wd2_timeout;

module_param(wd0_timeout, int, 0);
MODULE_PARM_DESC(wd0_timeout, "Default watchdog0 timeout in 1/10secs");
module_param(wd1_timeout, int, 0);
MODULE_PARM_DESC(wd1_timeout, "Default watchdog1 timeout in 1/10secs");
module_param(wd2_timeout, int, 0);
MODULE_PARM_DESC(wd2_timeout, "Default watchdog2 timeout in 1/10secs");

MODULE_AUTHOR("Eric Brower <[email protected]>");
MODULE_DESCRIPTION("Hardware watchdog driver for Sun Microsystems CP1400/1500");
MODULE_LICENSE("GPL");
MODULE_SUPPORTED_DEVICE("watchdog");

static void cpwd_writew(u16 val, void __iomem *addr)
{
    writew(cpu_to_le16(val), addr);
}
static u16 cpwd_readw(void __iomem *addr)
{
    u16 val = readw(addr);

    return le16_to_cpu(val);
}

static void cpwd_writeb(u8 val, void __iomem *addr)
{
    writeb(val, addr);
}

static u8 cpwd_readb(void __iomem *addr)
{
    return readb(addr);
}

/* Enable or disable watchdog interrupts
 * Because of the CP1400 defect this should only be
 * called during initialzation or by wd_[start|stop]timer()
 *
 * index    - sub-device index, or -1 for 'all'
 * enable   - non-zero to enable interrupts, zero to disable
 */
static void cpwd_toggleintr(struct cpwd *p, int index, int enable)
{
    unsigned char curregs = cpwd_readb(p->regs + PLD_IMASK);
    unsigned char setregs =
        (index == -1) ?
        (WD0_INTR_MASK | WD1_INTR_MASK | WD2_INTR_MASK) :
        (p->devs[index].intr_mask);

    if (enable == WD_INTR_ON)
        curregs &= ~setregs;
    else
        curregs |= setregs;

    cpwd_writeb(curregs, p->regs + PLD_IMASK);
}

/* Restarts timer with maximum limit value and
 * does not unset 'brokenstop' value.
 */
static void cpwd_resetbrokentimer(struct cpwd *p, int index)
{
    cpwd_toggleintr(p, index, WD_INTR_ON);
    cpwd_writew(WD_BLIMIT, p->devs[index].regs + WD_LIMIT);
}

/* Timer method called to reset stopped watchdogs--
 * because of the PLD bug on CP1400, we cannot mask
 * interrupts within the PLD so me must continually
 * reset the timers ad infinitum.
 */
static void cpwd_brokentimer(unsigned long data)
{
    struct cpwd *p = (struct cpwd *) data;
    int id, tripped = 0;

    /* kill a running timer instance, in case we
     * were called directly instead of by kernel timer
     */
    if (timer_pending(&cpwd_timer))
        del_timer(&cpwd_timer);

    for (id = 0; id < WD_NUMDEVS; id++) {
        if (p->devs[id].runstatus & WD_STAT_BSTOP) {
            ++tripped;
            cpwd_resetbrokentimer(p, id);
        }
    }

    if (tripped) {
        /* there is at least one timer brokenstopped-- reschedule */
        cpwd_timer.expires = WD_BTIMEOUT;
        add_timer(&cpwd_timer);
    }
}

/* Reset countdown timer with 'limit' value and continue countdown.
 * This will not start a stopped timer.
 */
static void cpwd_pingtimer(struct cpwd *p, int index)
{
    if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING)
        cpwd_readw(p->devs[index].regs + WD_DCNTR);
}

/* Stop a running watchdog timer-- the timer actually keeps
 * running, but the interrupt is masked so that no action is
 * taken upon expiration.
 */
static void cpwd_stoptimer(struct cpwd *p, int index)
{
    if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING) {
        cpwd_toggleintr(p, index, WD_INTR_OFF);

        if (p->broken) {
            p->devs[index].runstatus |= WD_STAT_BSTOP;
            cpwd_brokentimer((unsigned long) p);
        }
    }
}

/* Start a watchdog timer with the specified limit value
 * If the watchdog is running, it will be restarted with
 * the provided limit value.
 *
 * This function will enable interrupts on the specified
 * watchdog.
 */
static void cpwd_starttimer(struct cpwd *p, int index)
{
    if (p->broken)
        p->devs[index].runstatus &= ~WD_STAT_BSTOP;

    p->devs[index].runstatus &= ~WD_STAT_SVCD;

    cpwd_writew(p->devs[index].timeout, p->devs[index].regs + WD_LIMIT);
    cpwd_toggleintr(p, index, WD_INTR_ON);
}

static int cpwd_getstatus(struct cpwd *p, int index)
{
    unsigned char stat = cpwd_readb(p->devs[index].regs + WD_STATUS);
    unsigned char intr = cpwd_readb(p->devs[index].regs + PLD_IMASK);
    unsigned char ret  = WD_STOPPED;

    /* determine STOPPED */
    if (!stat)
        return ret;

    /* determine EXPIRED vs FREERUN vs RUNNING */
    else if (WD_S_EXPIRED & stat) {
        ret = WD_EXPIRED;
    } else if (WD_S_RUNNING & stat) {
        if (intr & p->devs[index].intr_mask) {
            ret = WD_FREERUN;
        } else {
            /* Fudge WD_EXPIRED status for defective CP1400--
             * IF timer is running
             *  AND brokenstop is set
             *  AND an interrupt has been serviced
             * we are WD_EXPIRED.
             *
             * IF timer is running
             *  AND brokenstop is set
             *  AND no interrupt has been serviced
             * we are WD_FREERUN.
             */
            if (p->broken &&
                (p->devs[index].runstatus & WD_STAT_BSTOP)) {
                if (p->devs[index].runstatus & WD_STAT_SVCD) {
                    ret = WD_EXPIRED;
                } else {
                    /* we could as well pretend
                     * we are expired */
                    ret = WD_FREERUN;
                }
            } else {
                ret = WD_RUNNING;
            }
        }
    }

    /* determine SERVICED */
    if (p->devs[index].runstatus & WD_STAT_SVCD)
        ret |= WD_SERVICED;

    return ret;
}

static irqreturn_t cpwd_interrupt(int irq, void *dev_id)
{
    struct cpwd *p = dev_id;

    /* Only WD0 will interrupt-- others are NMI and we won't
     * see them here....
     */
    spin_lock_irq(&p->lock);

    cpwd_stoptimer(p, WD0_ID);
    p->devs[WD0_ID].runstatus |=  WD_STAT_SVCD;

    spin_unlock_irq(&p->lock);

    return IRQ_HANDLED;
}

static int cpwd_open(struct inode *inode, struct file *f)
{
    struct cpwd *p = cpwd_device;

    mutex_lock(&cpwd_mutex);
    switch (iminor(inode)) {
    case WD0_MINOR:
    case WD1_MINOR:
    case WD2_MINOR:
        break;

    default:
        mutex_unlock(&cpwd_mutex);
        return -ENODEV;
    }

    /* Register IRQ on first open of device */
    if (!p->initialized) {
        if (request_irq(p->irq, &cpwd_interrupt,
                IRQF_SHARED, DRIVER_NAME, p)) {
            pr_err("Cannot register IRQ %d\n", p->irq);
            mutex_unlock(&cpwd_mutex);
            return -EBUSY;
        }
        p->initialized = true;
    }

    mutex_unlock(&cpwd_mutex);

    return nonseekable_open(inode, f);
}

static int cpwd_release(struct inode *inode, struct file *file)
{
    return 0;
}

static long cpwd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    static const struct watchdog_info info = {
        .options        = WDIOF_SETTIMEOUT,
        .firmware_version   = 1,
        .identity       = DRIVER_NAME,
    };
    void __user *argp = (void __user *)arg;
    struct inode *inode = file->f_path.dentry->d_inode;
    int index = iminor(inode) - WD0_MINOR;
    struct cpwd *p = cpwd_device;
    int setopt = 0;

    switch (cmd) {
    /* Generic Linux IOCTLs */
    case WDIOC_GETSUPPORT:
        if (copy_to_user(argp, &info, sizeof(struct watchdog_info)))
            return -EFAULT;
        break;

    case WDIOC_GETSTATUS:
    case WDIOC_GETBOOTSTATUS:
        if (put_user(0, (int __user *)argp))
            return -EFAULT;
        break;

    case WDIOC_KEEPALIVE:
        cpwd_pingtimer(p, index);
        break;

    case WDIOC_SETOPTIONS:
        if (copy_from_user(&setopt, argp, sizeof(unsigned int)))
            return -EFAULT;

        if (setopt & WDIOS_DISABLECARD) {
            if (p->enabled)
                return -EINVAL;
            cpwd_stoptimer(p, index);
        } else if (setopt & WDIOS_ENABLECARD) {
            cpwd_starttimer(p, index);
        } else {
            return -EINVAL;
        }
        break;

    /* Solaris-compatible IOCTLs */
    case WIOCGSTAT:
        setopt = cpwd_getstatus(p, index);
        if (copy_to_user(argp, &setopt, sizeof(unsigned int)))
            return -EFAULT;
        break;

    case WIOCSTART:
        cpwd_starttimer(p, index);
        break;

    case WIOCSTOP:
        if (p->enabled)
            return -EINVAL;

        cpwd_stoptimer(p, index);
        break;

    default:
        return -EINVAL;
    }

    return 0;
}

static long cpwd_compat_ioctl(struct file *file, unsigned int cmd,
                  unsigned long arg)
{
    int rval = -ENOIOCTLCMD;

    switch (cmd) {
    /* solaris ioctls are specific to this driver */
    case WIOCSTART:
    case WIOCSTOP:
    case WIOCGSTAT:
        mutex_lock(&cpwd_mutex);
        rval = cpwd_ioctl(file, cmd, arg);
        mutex_unlock(&cpwd_mutex);
        break;

    /* everything else is handled by the generic compat layer */
    default:
        break;
    }

    return rval;
}

static ssize_t cpwd_write(struct file *file, const char __user *buf,
              size_t count, loff_t *ppos)
{
    struct inode *inode = file->f_path.dentry->d_inode;
    struct cpwd *p = cpwd_device;
    int index = iminor(inode);

    if (count) {
        cpwd_pingtimer(p, index);
        return 1;
    }

    return 0;
}

static ssize_t cpwd_read(struct file *file, char __user *buffer,
             size_t count, loff_t *ppos)
{
    return -EINVAL;
}

static const struct file_operations cpwd_fops = {
    .owner =        THIS_MODULE,
    .unlocked_ioctl =   cpwd_ioctl,
    .compat_ioctl =     cpwd_compat_ioctl,
    .open =         cpwd_open,
    .write =        cpwd_write,
    .read =         cpwd_read,
    .release =      cpwd_release,
    .llseek =       no_llseek,
};

static int __devinit cpwd_probe(struct platform_device *op)
{
    struct device_node *options;
    const char *str_prop;
    const void *prop_val;
    int i, err = -EINVAL;
    struct cpwd *p;

    if (cpwd_device)
        return -EINVAL;

    p = kzalloc(sizeof(*p), GFP_KERNEL);
    err = -ENOMEM;
    if (!p) {
        pr_err("Unable to allocate struct cpwd\n");
        goto out;
    }

    p->irq = op->archdata.irqs[0];

    spin_lock_init(&p->lock);

    p->regs = of_ioremap(&op->resource[0], 0,
                 4 * WD_TIMER_REGSZ, DRIVER_NAME);
    if (!p->regs) {
        pr_err("Unable to map registers\n");
        goto out_free;
    }

    options = of_find_node_by_path("/options");
    err = -ENODEV;
    if (!options) {
        pr_err("Unable to find /options node\n");
        goto out_iounmap;
    }

    prop_val = of_get_property(options, "watchdog-enable?", NULL);
    p->enabled = (prop_val ? true : false);

    prop_val = of_get_property(options, "watchdog-reboot?", NULL);
    p->reboot = (prop_val ? true : false);

    str_prop = of_get_property(options, "watchdog-timeout", NULL);
    if (str_prop)
        p->timeout = simple_strtoul(str_prop, NULL, 10);

    /* CP1400s seem to have broken PLD implementations-- the
     * interrupt_mask register cannot be written, so no timer
     * interrupts can be masked within the PLD.
     */
    str_prop = of_get_property(op->dev.of_node, "model", NULL);
    p->broken = (str_prop && !strcmp(str_prop, WD_BADMODEL));

    if (!p->enabled)
        cpwd_toggleintr(p, -1, WD_INTR_OFF);

    for (i = 0; i < WD_NUMDEVS; i++) {
        static const char *cpwd_names[] = { "RIC", "XIR", "POR" };
        static int *parms[] = { &wd0_timeout,
                    &wd1_timeout,
                    &wd2_timeout };
        struct miscdevice *mp = &p->devs[i].misc;

        mp->minor = WD0_MINOR + i;
        mp->name = cpwd_names[i];
        mp->fops = &cpwd_fops;

        p->devs[i].regs = p->regs + (i * WD_TIMER_REGSZ);
        p->devs[i].intr_mask = (WD0_INTR_MASK << i);
        p->devs[i].runstatus &= ~WD_STAT_BSTOP;
        p->devs[i].runstatus |= WD_STAT_INIT;
        p->devs[i].timeout = p->timeout;
        if (*parms[i])
            p->devs[i].timeout = *parms[i];

        err = misc_register(&p->devs[i].misc);
        if (err) {
            pr_err("Could not register misc device for dev %d\n",
                   i);
            goto out_unregister;
        }
    }

    if (p->broken) {
        init_timer(&cpwd_timer);
        cpwd_timer.function = cpwd_brokentimer;
        cpwd_timer.data     = (unsigned long) p;
        cpwd_timer.expires  = WD_BTIMEOUT;

        pr_info("PLD defect workaround enabled for model %s\n",
            WD_BADMODEL);
    }

    dev_set_drvdata(&op->dev, p);
    cpwd_device = p;
    err = 0;

out:
    return err;

out_unregister:
    for (i--; i >= 0; i--)
        misc_deregister(&p->devs[i].misc);

out_iounmap:
    of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);

out_free:
    kfree(p);
    goto out;
}

static int __devexit cpwd_remove(struct platform_device *op)
{
    struct cpwd *p = dev_get_drvdata(&op->dev);
    int i;

    for (i = 0; i < WD_NUMDEVS; i++) {
        misc_deregister(&p->devs[i].misc);

        if (!p->enabled) {
            cpwd_stoptimer(p, i);
            if (p->devs[i].runstatus & WD_STAT_BSTOP)
                cpwd_resetbrokentimer(p, i);
        }
    }

    if (p->broken)
        del_timer_sync(&cpwd_timer);

    if (p->initialized)
        free_irq(p->irq, p);

    of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
    kfree(p);

    cpwd_device = NULL;

    return 0;
}

static const struct of_device_id cpwd_match[] = {
    {
        .name = "watchdog",
    },
    {},
};
MODULE_DEVICE_TABLE(of, cpwd_match);

static struct platform_driver cpwd_driver = {
    .driver = {
        .name = DRIVER_NAME,
        .owner = THIS_MODULE,
        .of_match_table = cpwd_match,
    },
    .probe      = cpwd_probe,
    .remove     = __devexit_p(cpwd_remove),
};

module_platform_driver(cpwd_driver);