78d88fc012
Add support for extra ioctl calls by adding a ioctl watchdog operation. This operation will be called before we do our own handling of ioctl commands. This way we can override the internal ioctl command handling and we can also add extra ioctl commands. The ioctl watchdog operation should return the appropriate error codes or -ENOIOCTLCMD if the ioctl command should be handled through the internal ioctl handling of the framework. Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Wim Van Sebroeck <wim@iguana.be> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Wolfram Sang <w.sang@pengutronix.de>
393 lines
9.9 KiB
C
393 lines
9.9 KiB
C
/*
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* watchdog_dev.c
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*
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* (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
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* All Rights Reserved.
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*
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* (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
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*
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*
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* This source code is part of the generic code that can be used
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* by all the watchdog timer drivers.
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*
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* This part of the generic code takes care of the following
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* misc device: /dev/watchdog.
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*
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* Based on source code of the following authors:
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* Matt Domsch <Matt_Domsch@dell.com>,
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* Rob Radez <rob@osinvestor.com>,
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* Rusty Lynch <rusty@linux.co.intel.com>
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* Satyam Sharma <satyam@infradead.org>
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* Randy Dunlap <randy.dunlap@oracle.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
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* admit liability nor provide warranty for any of this software.
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* This material is provided "AS-IS" and at no charge.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h> /* For module stuff/... */
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#include <linux/types.h> /* For standard types (like size_t) */
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#include <linux/errno.h> /* For the -ENODEV/... values */
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#include <linux/kernel.h> /* For printk/panic/... */
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#include <linux/fs.h> /* For file operations */
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#include <linux/watchdog.h> /* For watchdog specific items */
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#include <linux/miscdevice.h> /* For handling misc devices */
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#include <linux/init.h> /* For __init/__exit/... */
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#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
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/* make sure we only register one /dev/watchdog device */
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static unsigned long watchdog_dev_busy;
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/* the watchdog device behind /dev/watchdog */
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static struct watchdog_device *wdd;
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/*
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* watchdog_ping: ping the watchdog.
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* @wddev: the watchdog device to ping
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*
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* If the watchdog has no own ping operation then it needs to be
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* restarted via the start operation. This wrapper function does
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* exactly that.
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* We only ping when the watchdog device is running.
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*/
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static int watchdog_ping(struct watchdog_device *wddev)
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{
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if (test_bit(WDOG_ACTIVE, &wdd->status)) {
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if (wddev->ops->ping)
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return wddev->ops->ping(wddev); /* ping the watchdog */
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else
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return wddev->ops->start(wddev); /* restart watchdog */
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}
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return 0;
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}
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/*
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* watchdog_start: wrapper to start the watchdog.
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* @wddev: the watchdog device to start
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*
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* Start the watchdog if it is not active and mark it active.
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* This function returns zero on success or a negative errno code for
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* failure.
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*/
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static int watchdog_start(struct watchdog_device *wddev)
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{
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int err;
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if (!test_bit(WDOG_ACTIVE, &wdd->status)) {
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err = wddev->ops->start(wddev);
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if (err < 0)
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return err;
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set_bit(WDOG_ACTIVE, &wdd->status);
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}
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return 0;
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}
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/*
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* watchdog_stop: wrapper to stop the watchdog.
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* @wddev: the watchdog device to stop
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*
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* Stop the watchdog if it is still active and unmark it active.
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* This function returns zero on success or a negative errno code for
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* failure.
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* If the 'nowayout' feature was set, the watchdog cannot be stopped.
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*/
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static int watchdog_stop(struct watchdog_device *wddev)
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{
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int err = -EBUSY;
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if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
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pr_info("%s: nowayout prevents watchdog to be stopped!\n",
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wdd->info->identity);
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return err;
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}
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if (test_bit(WDOG_ACTIVE, &wdd->status)) {
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err = wddev->ops->stop(wddev);
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if (err < 0)
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return err;
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clear_bit(WDOG_ACTIVE, &wdd->status);
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}
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return 0;
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}
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/*
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* watchdog_write: writes to the watchdog.
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* @file: file from VFS
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* @data: user address of data
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* @len: length of data
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* @ppos: pointer to the file offset
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*
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* A write to a watchdog device is defined as a keepalive ping.
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* Writing the magic 'V' sequence allows the next close to turn
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* off the watchdog (if 'nowayout' is not set).
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*/
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static ssize_t watchdog_write(struct file *file, const char __user *data,
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size_t len, loff_t *ppos)
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{
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size_t i;
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char c;
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if (len == 0)
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return 0;
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/*
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* Note: just in case someone wrote the magic character
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* five months ago...
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*/
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clear_bit(WDOG_ALLOW_RELEASE, &wdd->status);
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/* scan to see whether or not we got the magic character */
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for (i = 0; i != len; i++) {
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if (get_user(c, data + i))
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return -EFAULT;
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if (c == 'V')
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set_bit(WDOG_ALLOW_RELEASE, &wdd->status);
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}
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/* someone wrote to us, so we send the watchdog a keepalive ping */
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watchdog_ping(wdd);
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return len;
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}
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/*
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* watchdog_ioctl: handle the different ioctl's for the watchdog device.
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* @file: file handle to the device
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* @cmd: watchdog command
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* @arg: argument pointer
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*
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* The watchdog API defines a common set of functions for all watchdogs
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* according to their available features.
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*/
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static long watchdog_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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void __user *argp = (void __user *)arg;
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int __user *p = argp;
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unsigned int val;
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int err;
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if (wdd->ops->ioctl) {
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err = wdd->ops->ioctl(wdd, cmd, arg);
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if (err != -ENOIOCTLCMD)
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return err;
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}
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switch (cmd) {
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case WDIOC_GETSUPPORT:
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return copy_to_user(argp, wdd->info,
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sizeof(struct watchdog_info)) ? -EFAULT : 0;
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case WDIOC_GETSTATUS:
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val = wdd->ops->status ? wdd->ops->status(wdd) : 0;
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return put_user(val, p);
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case WDIOC_GETBOOTSTATUS:
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return put_user(wdd->bootstatus, p);
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case WDIOC_SETOPTIONS:
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if (get_user(val, p))
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return -EFAULT;
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if (val & WDIOS_DISABLECARD) {
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err = watchdog_stop(wdd);
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if (err < 0)
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return err;
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}
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if (val & WDIOS_ENABLECARD) {
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err = watchdog_start(wdd);
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if (err < 0)
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return err;
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}
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return 0;
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case WDIOC_KEEPALIVE:
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if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
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return -EOPNOTSUPP;
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watchdog_ping(wdd);
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return 0;
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case WDIOC_SETTIMEOUT:
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if ((wdd->ops->set_timeout == NULL) ||
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!(wdd->info->options & WDIOF_SETTIMEOUT))
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return -EOPNOTSUPP;
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if (get_user(val, p))
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return -EFAULT;
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err = wdd->ops->set_timeout(wdd, val);
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if (err < 0)
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return err;
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wdd->timeout = val;
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/* If the watchdog is active then we send a keepalive ping
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* to make sure that the watchdog keep's running (and if
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* possible that it takes the new timeout) */
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watchdog_ping(wdd);
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/* Fall */
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case WDIOC_GETTIMEOUT:
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/* timeout == 0 means that we don't know the timeout */
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if (wdd->timeout == 0)
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return -EOPNOTSUPP;
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return put_user(wdd->timeout, p);
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default:
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return -ENOTTY;
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}
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}
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/*
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* watchdog_open: open the /dev/watchdog device.
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* @inode: inode of device
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* @file: file handle to device
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*
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* When the /dev/watchdog device gets opened, we start the watchdog.
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* Watch out: the /dev/watchdog device is single open, so we make sure
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* it can only be opened once.
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*/
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static int watchdog_open(struct inode *inode, struct file *file)
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{
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int err = -EBUSY;
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/* the watchdog is single open! */
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if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status))
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return -EBUSY;
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/*
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* If the /dev/watchdog device is open, we don't want the module
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* to be unloaded.
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*/
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if (!try_module_get(wdd->ops->owner))
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goto out;
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err = watchdog_start(wdd);
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if (err < 0)
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goto out_mod;
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/* dev/watchdog is a virtual (and thus non-seekable) filesystem */
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return nonseekable_open(inode, file);
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out_mod:
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module_put(wdd->ops->owner);
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out:
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clear_bit(WDOG_DEV_OPEN, &wdd->status);
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return err;
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}
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/*
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* watchdog_release: release the /dev/watchdog device.
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* @inode: inode of device
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* @file: file handle to device
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*
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* This is the code for when /dev/watchdog gets closed. We will only
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* stop the watchdog when we have received the magic char (and nowayout
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* was not set), else the watchdog will keep running.
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*/
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static int watchdog_release(struct inode *inode, struct file *file)
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{
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int err = -EBUSY;
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/*
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* We only stop the watchdog if we received the magic character
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* or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
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* watchdog_stop will fail.
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*/
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if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) ||
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!(wdd->info->options & WDIOF_MAGICCLOSE))
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err = watchdog_stop(wdd);
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/* If the watchdog was not stopped, send a keepalive ping */
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if (err < 0) {
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pr_crit("%s: watchdog did not stop!\n", wdd->info->identity);
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watchdog_ping(wdd);
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}
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/* Allow the owner module to be unloaded again */
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module_put(wdd->ops->owner);
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/* make sure that /dev/watchdog can be re-opened */
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clear_bit(WDOG_DEV_OPEN, &wdd->status);
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return 0;
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}
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static const struct file_operations watchdog_fops = {
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.owner = THIS_MODULE,
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.write = watchdog_write,
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.unlocked_ioctl = watchdog_ioctl,
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.open = watchdog_open,
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.release = watchdog_release,
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};
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static struct miscdevice watchdog_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &watchdog_fops,
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};
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/*
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* watchdog_dev_register:
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* @watchdog: watchdog device
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*
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* Register a watchdog device as /dev/watchdog. /dev/watchdog
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* is actually a miscdevice and thus we set it up like that.
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*/
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int watchdog_dev_register(struct watchdog_device *watchdog)
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{
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int err;
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/* Only one device can register for /dev/watchdog */
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if (test_and_set_bit(0, &watchdog_dev_busy)) {
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pr_err("only one watchdog can use /dev/watchdog.\n");
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return -EBUSY;
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}
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wdd = watchdog;
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err = misc_register(&watchdog_miscdev);
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if (err != 0) {
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pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
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watchdog->info->identity, WATCHDOG_MINOR, err);
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goto out;
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}
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return 0;
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out:
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wdd = NULL;
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clear_bit(0, &watchdog_dev_busy);
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return err;
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}
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/*
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* watchdog_dev_unregister:
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* @watchdog: watchdog device
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*
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* Deregister the /dev/watchdog device.
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*/
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int watchdog_dev_unregister(struct watchdog_device *watchdog)
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{
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/* Check that a watchdog device was registered in the past */
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if (!test_bit(0, &watchdog_dev_busy) || !wdd)
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return -ENODEV;
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/* We can only unregister the watchdog device that was registered */
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if (watchdog != wdd) {
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pr_err("%s: watchdog was not registered as /dev/watchdog.\n",
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watchdog->info->identity);
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return -ENODEV;
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}
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misc_deregister(&watchdog_miscdev);
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wdd = NULL;
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clear_bit(0, &watchdog_dev_busy);
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return 0;
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}
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