/* * kernel API * * * Copyright (C) 2005-2009 Rodolfo Giometti <giometti@linux.it> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/init.h> #include <linux/sched.h> #include <linux/time.h> #include <linux/spinlock.h> #include <linux/idr.h> #include <linux/fs.h> #include <linux/pps_kernel.h> /* * Global variables */ DEFINE_SPINLOCK(pps_idr_lock); DEFINE_IDR(pps_idr); /* * Local functions */ static void pps_add_offset(struct pps_ktime *ts, struct pps_ktime *offset) { ts->nsec += offset->nsec; while (ts->nsec >= NSEC_PER_SEC) { ts->nsec -= NSEC_PER_SEC; ts->sec++; } while (ts->nsec < 0) { ts->nsec += NSEC_PER_SEC; ts->sec--; } ts->sec += offset->sec; } /* * Exported functions */ /* pps_get_source - find a PPS source * @source: the PPS source ID. * * This function is used to find an already registered PPS source into the * system. * * The function returns NULL if found nothing, otherwise it returns a pointer * to the PPS source data struct (the refcounter is incremented by 1). */ struct pps_device *pps_get_source(int source) { struct pps_device *pps; unsigned long flags; spin_lock_irqsave(&pps_idr_lock, flags); pps = idr_find(&pps_idr, source); if (pps != NULL) atomic_inc(&pps->usage); spin_unlock_irqrestore(&pps_idr_lock, flags); return pps; } /* pps_put_source - free the PPS source data * @pps: a pointer to the PPS source. * * This function is used to free a PPS data struct if its refcount is 0. */ void pps_put_source(struct pps_device *pps) { unsigned long flags; spin_lock_irqsave(&pps_idr_lock, flags); BUG_ON(atomic_read(&pps->usage) == 0); if (!atomic_dec_and_test(&pps->usage)) { pps = NULL; goto exit; } /* No more reference to the PPS source. We can safely remove the * PPS data struct. */ idr_remove(&pps_idr, pps->id); exit: spin_unlock_irqrestore(&pps_idr_lock, flags); kfree(pps); } /* pps_register_source - add a PPS source in the system * @info: the PPS info struct * @default_params: the default PPS parameters of the new source * * This function is used to add a new PPS source in the system. The new * source is described by info's fields and it will have, as default PPS * parameters, the ones specified into default_params. * * The function returns, in case of success, the PPS source ID. */ int pps_register_source(struct pps_source_info *info, int default_params) { struct pps_device *pps; int id; int err; /* Sanity checks */ if ((info->mode & default_params) != default_params) { printk(KERN_ERR "pps: %s: unsupported default parameters\n", info->name); err = -EINVAL; goto pps_register_source_exit; } if ((info->mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) != 0 && info->echo == NULL) { printk(KERN_ERR "pps: %s: echo function is not defined\n", info->name); err = -EINVAL; goto pps_register_source_exit; } if ((info->mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) { printk(KERN_ERR "pps: %s: unspecified time format\n", info->name); err = -EINVAL; goto pps_register_source_exit; } /* Allocate memory for the new PPS source struct */ pps = kzalloc(sizeof(struct pps_device), GFP_KERNEL); if (pps == NULL) { err = -ENOMEM; goto pps_register_source_exit; } /* These initializations must be done before calling idr_get_new() * in order to avoid reces into pps_event(). */ pps->params.api_version = PPS_API_VERS; pps->params.mode = default_params; pps->info = *info; init_waitqueue_head(&pps->queue); spin_lock_init(&pps->lock); atomic_set(&pps->usage, 1); /* Get new ID for the new PPS source */ if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) { err = -ENOMEM; goto kfree_pps; } spin_lock_irq(&pps_idr_lock); /* Now really allocate the PPS source. * After idr_get_new() calling the new source will be freely available * into the kernel. */ err = idr_get_new(&pps_idr, pps, &id); if (err < 0) { spin_unlock_irq(&pps_idr_lock); goto kfree_pps; } id = id & MAX_ID_MASK; if (id >= PPS_MAX_SOURCES) { spin_unlock_irq(&pps_idr_lock); printk(KERN_ERR "pps: %s: too many PPS sources in the system\n", info->name); err = -EBUSY; goto free_idr; } pps->id = id; spin_unlock_irq(&pps_idr_lock); /* Create the char device */ err = pps_register_cdev(pps); if (err < 0) { printk(KERN_ERR "pps: %s: unable to create char device\n", info->name); goto free_idr; } pr_info("new PPS source %s at ID %d\n", info->name, id); return id; free_idr: spin_lock_irq(&pps_idr_lock); idr_remove(&pps_idr, id); spin_unlock_irq(&pps_idr_lock); kfree_pps: kfree(pps); pps_register_source_exit: printk(KERN_ERR "pps: %s: unable to register source\n", info->name); return err; } EXPORT_SYMBOL(pps_register_source); /* pps_unregister_source - remove a PPS source from the system * @source: the PPS source ID * * This function is used to remove a previously registered PPS source from * the system. */ void pps_unregister_source(int source) { struct pps_device *pps; spin_lock_irq(&pps_idr_lock); pps = idr_find(&pps_idr, source); if (!pps) { BUG(); spin_unlock_irq(&pps_idr_lock); return; } spin_unlock_irq(&pps_idr_lock); pps_unregister_cdev(pps); pps_put_source(pps); } EXPORT_SYMBOL(pps_unregister_source); /* pps_event - register a PPS event into the system * @source: the PPS source ID * @ts: the event timestamp * @event: the event type * @data: userdef pointer * * This function is used by each PPS client in order to register a new * PPS event into the system (it's usually called inside an IRQ handler). * * If an echo function is associated with the PPS source it will be called * as: * pps->info.echo(source, event, data); */ void pps_event(int source, struct pps_ktime *ts, int event, void *data) { struct pps_device *pps; unsigned long flags; int captured = 0; if ((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0) { printk(KERN_ERR "pps: unknown event (%x) for source %d\n", event, source); return; } pps = pps_get_source(source); if (!pps) return; pr_debug("PPS event on source %d at %llu.%06u\n", pps->id, (unsigned long long) ts->sec, ts->nsec); spin_lock_irqsave(&pps->lock, flags); /* Must call the echo function? */ if ((pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR))) pps->info.echo(source, event, data); /* Check the event */ pps->current_mode = pps->params.mode; if ((event & PPS_CAPTUREASSERT) & (pps->params.mode & PPS_CAPTUREASSERT)) { /* We have to add an offset? */ if (pps->params.mode & PPS_OFFSETASSERT) pps_add_offset(ts, &pps->params.assert_off_tu); /* Save the time stamp */ pps->assert_tu = *ts; pps->assert_sequence++; pr_debug("capture assert seq #%u for source %d\n", pps->assert_sequence, source); captured = ~0; } if ((event & PPS_CAPTURECLEAR) & (pps->params.mode & PPS_CAPTURECLEAR)) { /* We have to add an offset? */ if (pps->params.mode & PPS_OFFSETCLEAR) pps_add_offset(ts, &pps->params.clear_off_tu); /* Save the time stamp */ pps->clear_tu = *ts; pps->clear_sequence++; pr_debug("capture clear seq #%u for source %d\n", pps->clear_sequence, source); captured = ~0; } /* Wake up iif captured somthing */ if (captured) { pps->go = ~0; wake_up_interruptible(&pps->queue); kill_fasync(&pps->async_queue, SIGIO, POLL_IN); } spin_unlock_irqrestore(&pps->lock, flags); /* Now we can release the PPS source for (possible) deregistration */ pps_put_source(pps); } EXPORT_SYMBOL(pps_event);