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Re: [PATCH] Added MIPS RM9K watchdog driver

To: Thomas Koeller <thomas@koeller.dyndns.org>, Ralf Baechle <ralf@linux-mips.org>, Dave Jones <davej@redhat.com>, Alan Cox <alan@lxorguk.ukuu.org.uk>, Sam Ravnborg <sam@ravnborg.org>, "Randy. Dunlap" <rdunlap@xenotime.net>, Alexey Dobriyan <adobriyan@gmail.com>
Subject: Re: [PATCH] Added MIPS RM9K watchdog driver
From: Wim Van Sebroeck <wim@iguana.be>
Date: Wed, 1 Nov 2006 19:46:33 +0100
Cc: linux-kernel@vger.kernel.org, linux-mips@linux-mips.org
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.4.2.1i
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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