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    Subject[PATCH 4/9] watchdog: WatchDog Timer Driver Core - Add WDIOC_SETOPTIONS ioctl
    Date
    This part add's the WDIOC_SETOPTIONS ioctl functionality
    to the WatchDog Timer Driver Core 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>
    ---
    Documentation/watchdog/watchdog-kernel-api.txt | 9 ++-
    drivers/watchdog/watchdog_dev.c | 79 +++++++++++++++++++++--
    include/linux/watchdog.h | 1 +
    3 files changed, 80 insertions(+), 9 deletions(-)

    diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
    index abbcf2c..429f81b 100644
    --- a/Documentation/watchdog/watchdog-kernel-api.txt
    +++ b/Documentation/watchdog/watchdog-kernel-api.txt
    @@ -56,8 +56,9 @@ It contains following fields:
    This data should only be accessed via the watchdog_set_drvadata and
    watchdog_get_drvdata routines.
    * status: this field contains a number of status bits that give extra
    - information about the status of the device (Like: is the device opened via
    - the /dev/watchdog interface or not, ...).
    + information about the status of the device (Like: is the watchdog timer
    + running/active, is the device opened via the /dev/watchdog interface or not,
    + ...).

    The list of watchdog operations is defined as:

    @@ -109,6 +110,10 @@ they are supported. These optional routines/operations are:

    The status bits should (preferably) be set with the set_bit and clear_bit alike
    bit-operations. The status bits that are defined are:
    +* WDOG_ACTIVE: this status bit indicates whether or not a watchdog timer device
    + is active or not. When the watchdog is active after booting, then you should
    + set this status bit (Note: when you register the watchdog timer device with
    + this bit set, then opening /dev/watchdog will skip the start operation)
    * WDOG_DEV_OPEN: this status bit shows whether or not the watchdog device
    was opened via /dev/watchdog.
    (This bit should only be used by the WatchDog Timer Driver Core).
    diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
    index 2fb4cec..9f5550e 100644
    --- a/drivers/watchdog/watchdog_dev.c
    +++ b/drivers/watchdog/watchdog_dev.c
    @@ -54,14 +54,64 @@ static struct watchdog_device *wdd;
    * If the watchdog has no own ping operation then it needs to be
    * restarted via the start operation. This wrapper function does
    * exactly that.
    + * We only ping when the watchdog device is running.
    */

    static int watchdog_ping(struct watchdog_device *wddev)
    {
    - if (wddev->ops->ping)
    - return wddev->ops->ping(wddev); /* ping the watchdog */
    - else
    - return wddev->ops->start(wddev); /* restart the watchdog */
    + if (test_bit(WDOG_ACTIVE, &wdd->status)) {
    + if (wddev->ops->ping)
    + return wddev->ops->ping(wddev); /* ping the watchdog */
    + else
    + return wddev->ops->start(wddev); /* restart watchdog */
    + }
    + return 0;
    +}
    +
    +/*
    + * watchdog_start: wrapper to start the watchdog.
    + * @wddev: the watchdog device to start
    + *
    + * Start the watchdog if it is not active and mark it active.
    + * This function returns zero on success or a negative errno code for
    + * failure.
    + */
    +
    +static int watchdog_start(struct watchdog_device *wddev)
    +{
    + int err;
    +
    + if (!test_bit(WDOG_ACTIVE, &wdd->status)) {
    + err = wddev->ops->start(wddev);
    + if (err < 0)
    + return err;
    +
    + set_bit(WDOG_ACTIVE, &wdd->status);
    + }
    + return 0;
    +}
    +
    +/*
    + * watchdog_stop: wrapper to stop the watchdog.
    + * @wddev: the watchdog device to stop
    + *
    + * Stop the watchdog if it is still active and unmark it active.
    + * This function returns zero on success or a negative errno code for
    + * failure.
    + */
    +
    +static int watchdog_stop(struct watchdog_device *wddev)
    +{
    + int err;
    +
    + if (test_bit(WDOG_ACTIVE, &wdd->status)) {
    + err = wddev->ops->stop(wddev);
    + if (err < 0)
    + return err;
    +
    + clear_bit(WDOG_ACTIVE, &wdd->status);
    + }
    + return 0;
    }

    /*
    @@ -110,6 +160,7 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    unsigned int val;
    + int err;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
    @@ -120,6 +171,20 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
    return put_user(val, p);
    case WDIOC_GETBOOTSTATUS:
    return put_user(wdd->bootstatus, p);
    + case WDIOC_SETOPTIONS:
    + if (get_user(val, p))
    + return -EFAULT;
    + if (val & WDIOS_DISABLECARD) {
    + err = watchdog_stop(wdd);
    + if (err < 0)
    + return err;
    + }
    + if (val & WDIOS_ENABLECARD) {
    + err = watchdog_start(wdd);
    + if (err < 0)
    + return err;
    + }
    + return 0;
    case WDIOC_KEEPALIVE:
    if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
    return -EOPNOTSUPP;
    @@ -155,7 +220,7 @@ static int watchdog_open(struct inode *inode, struct file *file)
    if (!try_module_get(wdd->ops->owner))
    goto out;

    - err = wdd->ops->start(wdd);
    + err = watchdog_start(wdd);
    if (err < 0)
    goto out_mod;

    @@ -181,8 +246,8 @@ static int watchdog_release(struct inode *inode, struct file *file)
    {
    int err;

    - err = wdd->ops->stop(wdd);
    - if (err != 0) {
    + err = watchdog_stop(wdd);
    + if (err < 0) {
    pr_crit("%s: watchdog did not stop!\n", wdd->info->identity);
    watchdog_ping(wdd);
    }
    diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
    index 29ff808..db46fe8 100644
    --- a/include/linux/watchdog.h
    +++ b/include/linux/watchdog.h
    @@ -106,6 +106,7 @@ struct watchdog_device {
    void *driver_data;
    unsigned long status;
    /* Bit numbers for status flags */
    +#define WDOG_ACTIVE 0 /* Is the watchdog running/active */
    #define WDOG_DEV_OPEN 1 /* Opened via /dev/watchdog ? */
    };

    --
    1.7.6


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