Re: [RFC] PPS: Implementing LinuxPPS API with new syscalls

[Rodolfo Giometti]

On Wed, Jun 06, 2007 at 01:29:34PM -0700, Andrew Morton wrote:

> >    asmlinkage long sys_time_pps_find(int cmd, int __user *source,
> >                                           char __user *name, int namelen,
> >                                           char __user *path, int pathlen);

Try to find a PPS source into the system giving one of its feature.

With cmd==PPS_FIND_SRC we check for a PPS source with index number
equal to *source, if *source==-1 we just ask for the first PPS source
defined into the system.

With cmd=PPS_FIND_PATH we check for a PPS source with path name equal
to path.

Selected source is returned into *source and PPS source info are
placed into path and name arrays.

> >    asmlinkage long sys_time_pps_getparams(int source,
> >                                           struct pps_params __user *params);

struct pps_params {
        int api_version;                /* API version # */
        int mode;                       /* mode bits */
        union pps_timeu assert_off_tu;  /* offset compensation for assert */
        union pps_timeu clear_off_tu;   /* offset compensation for clear */
};

Given a PPS source index returns its parameters setting.

> >    asmlinkage long sys_time_pps_setparams(int source,
> >                                           const struct pps_params __user *params);

Sets PPS source parameters.

> >    asmlinkage long sys_time_pps_getcap(int source, int __user *mode);

Given a	PPS source index returns its functioning modes.

> >    asmlinkage long sys_time_pps_fetch(int source, const int tsformat,
> >                                           struct pps_info __user *info,
> >                                           const struct timespec __user *timeout);

struct pps_info {
        unsigned long assert_sequence;  /* seq. num. of assert event */
        unsigned long clear_sequence;   /* seq. num. of clear event */
        union pps_timeu assert_tu;      /* time of assert event */
        union pps_timeu clear_tu;       /* time of clear event */
        int current_mode;               /* current mode bits */
};

Given a PPS source index, a time format and, optionally, a timeout
time returns PPS time data.

Further info on these structs can be get on RFC 2783.

Apart sys_time_pps_find() the other syscalls derive directly from RFC
2783 suggestions.

I hope these info are enough... :)

Rodolfo

-- 

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