diff options
| -rw-r--r-- | drivers/pps/pps.c | 33 | ||||
| -rw-r--r-- | include/linux/pps_kernel.h | 17 |
2 files changed, 47 insertions, 3 deletions
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c index 2420d5af0583..a70e384262e5 100644 --- a/drivers/pps/pps.c +++ b/drivers/pps/pps.c @@ -352,11 +352,44 @@ free_idr: void pps_unregister_cdev(struct pps_device *pps) { + pps->lookup_cookie = NULL; device_destroy(pps_class, pps->dev->devt); cdev_del(&pps->cdev); } /* + * Look up a pps device by magic cookie. + * The cookie is usually a pointer to some enclosing device, but this + * code doesn't care; you should never be dereferencing it. + * + * This is a bit of a kludge that is currently used only by the PPS + * serial line discipline. It may need to be tweaked when a second user + * is found. + * + * There is no function interface for setting the lookup_cookie field. + * It's initialized to NULL when the pps device is created, and if a + * client wants to use it, just fill it in afterward. + * + * The cookie is automatically set to NULL in pps_unregister_source() + * so that it will not be used again, even if the pps device cannot + * be removed from the idr due to pending references holding the minor + * number in use. + */ +struct pps_device *pps_lookup_dev(void const *cookie) +{ + struct pps_device *pps; + unsigned id; + + rcu_read_lock(); + idr_for_each_entry(&pps_idr, pps, id) + if (cookie == pps->lookup_cookie) + break; + rcu_read_unlock(); + return pps; +} +EXPORT_SYMBOL(pps_lookup_dev); + +/* * Module stuff */ diff --git a/include/linux/pps_kernel.h b/include/linux/pps_kernel.h index 0cc45ae1afd5..7db3eb93a079 100644 --- a/include/linux/pps_kernel.h +++ b/include/linux/pps_kernel.h @@ -43,7 +43,7 @@ struct pps_source_info { int event, void *data); /* PPS echo function */ struct module *owner; - struct device *dev; + struct device *dev; /* Parent device for device_create */ }; struct pps_event_time { @@ -69,6 +69,7 @@ struct pps_device { wait_queue_head_t queue; /* PPS event queue */ unsigned int id; /* PPS source unique ID */ + void const *lookup_cookie; /* pps_lookup_dev only */ struct cdev cdev; struct device *dev; struct fasync_struct *async_queue; /* fasync method */ @@ -82,16 +83,26 @@ struct pps_device { extern struct device_attribute pps_attrs[]; /* + * Internal functions. + * + * These are not actually part of the exported API, but this is a + * convenient header file to put them in. + */ + +extern int pps_register_cdev(struct pps_device *pps); +extern void pps_unregister_cdev(struct pps_device *pps); + +/* * Exported functions */ extern struct pps_device *pps_register_source( struct pps_source_info *info, int default_params); extern void pps_unregister_source(struct pps_device *pps); -extern int pps_register_cdev(struct pps_device *pps); -extern void pps_unregister_cdev(struct pps_device *pps); extern void pps_event(struct pps_device *pps, struct pps_event_time *ts, int event, void *data); +/* Look up a pps device by magic cookie */ +struct pps_device *pps_lookup_dev(void const *cookie); static inline void timespec_to_pps_ktime(struct pps_ktime *kt, struct timespec ts) |