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    SubjectRe: [RFC] Watchdog device class
    Hi Rudolf,

    > > It's not about different approaches: we have to find the best thing for watchdog
    > > devicesi, so the best thing is to talk about pro's and con's and see what we should
    > > do best. (I for instance didn't come to the sysfs part yet of my code (which would
    > > be in watchdog_sysfs.c)
    >
    > Ok I will look into your code.

    Please have a look at the experimental code in the linux-2.6-watchdog-experimental git tree
    (http://www.kernel.org/git/?p=linux/kernel/git/wim/linux-2.6-watchdog-experimental.git;a=summary).

    It's a first draft of the generic code. (it's split into tree main parts: the core code, the
    /dev/watchdog code and the sysfs code). (Note: I used Greg's new "class" device setup).
    And it basically uses the following operations and watchdog_device structure:

    struct watchdog_ops {
    /* mandatory routines */
    int (*start)(struct watchdog_device *); /* operation = start watchdog */
    int (*stop)(struct watchdog_device *); /* operation = stop watchdog */
    int (*keepalive)(struct watchdog_device *); /* operation = send keepalive ping */
    /* optional routines */
    int (*set_heartbeat)(struct watchdog_device *,int); /* operation = set watchdog's heartbeat */
    int (*get_status)(struct watchdog_device *,int *); /* operation = get the watchdog's status */
    int (*get_timeleft)(struct watchdog_device *, int *); /* operation = get the time left before reboot */
    int (*sys_restart)(struct watchdog_device *); /* operation = force a system_restart for rebooting */
    };

    struct watchdog_device {
    unsigned char name[32]; /* The watchdog's 'identity' */
    unsigned long options; /* The supported capabilities/options */
    unsigned long firmware; /* The Watchdog's Firmware version */
    int heartbeat; /* The watchdog's heartbeat */
    int nowayout; /* The nowayout setting for this watchdog */
    int bootstatus; /* The watchdog's bootstatus */
    int temppanic; /* wether or not to panic on temperature trip's */
    struct watchdog_ops *watchdog_ops; /* link to watchdog_ops */

    /* watchdog status (register/unregister) state machine */
    enum { WATCHDOG_UNINITIALIZED=0,
    WATCHDOG_REGISTERED, /* completed register_watchdogdevice */
    WATCHDOG_STARTED, /* watchdog device started */
    WATCHDOG_STOPPED, /* watchdog device stopped */
    WATCHDOG_UNREGISTERED, /* completed unregister_watchdogdevice */
    } watchdog_state;

    struct semaphore sem; /* locks this structure */

    struct device *cdev; /* Sysfs watchdog class device */

    /* From here on everything is device dependent */
    void *private;
    };

    There are still a number of things to be added:
    * have a list under register_watchdogdevice so that we can register multiple watchdog devices
    (Note: only one watchdog device will be linked to /dev/watchdog)
    * add pre-timeout stuff
    * clean-up sysfs code
    * do proper locking
    * add documentation
    * make docbook ready
    * decide how we will handle the old temperature ioctl
    ...

    All comments/suggestions are welcome. Let's see/discuss what's missing, what we should do different, ...

    Greetings,
    Wim.

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