Root/drivers/pps/pps.c

1/*
2 * PPS core file
3 *
4 *
5 * Copyright (C) 2005-2009 Rodolfo Giometti <giometti@linux.it>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 */
21
22#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23
24#include <linux/kernel.h>
25#include <linux/module.h>
26#include <linux/init.h>
27#include <linux/sched.h>
28#include <linux/uaccess.h>
29#include <linux/idr.h>
30#include <linux/mutex.h>
31#include <linux/cdev.h>
32#include <linux/poll.h>
33#include <linux/pps_kernel.h>
34#include <linux/slab.h>
35
36#include "kc.h"
37
38/*
39 * Local variables
40 */
41
42static dev_t pps_devt;
43static struct class *pps_class;
44
45static DEFINE_MUTEX(pps_idr_lock);
46static DEFINE_IDR(pps_idr);
47
48/*
49 * Char device methods
50 */
51
52static unsigned int pps_cdev_poll(struct file *file, poll_table *wait)
53{
54    struct pps_device *pps = file->private_data;
55
56    poll_wait(file, &pps->queue, wait);
57
58    return POLLIN | POLLRDNORM;
59}
60
61static int pps_cdev_fasync(int fd, struct file *file, int on)
62{
63    struct pps_device *pps = file->private_data;
64    return fasync_helper(fd, file, on, &pps->async_queue);
65}
66
67static long pps_cdev_ioctl(struct file *file,
68        unsigned int cmd, unsigned long arg)
69{
70    struct pps_device *pps = file->private_data;
71    struct pps_kparams params;
72    void __user *uarg = (void __user *) arg;
73    int __user *iuarg = (int __user *) arg;
74    int err;
75
76    switch (cmd) {
77    case PPS_GETPARAMS:
78        dev_dbg(pps->dev, "PPS_GETPARAMS\n");
79
80        spin_lock_irq(&pps->lock);
81
82        /* Get the current parameters */
83        params = pps->params;
84
85        spin_unlock_irq(&pps->lock);
86
87        err = copy_to_user(uarg, &params, sizeof(struct pps_kparams));
88        if (err)
89            return -EFAULT;
90
91        break;
92
93    case PPS_SETPARAMS:
94        dev_dbg(pps->dev, "PPS_SETPARAMS\n");
95
96        /* Check the capabilities */
97        if (!capable(CAP_SYS_TIME))
98            return -EPERM;
99
100        err = copy_from_user(&params, uarg, sizeof(struct pps_kparams));
101        if (err)
102            return -EFAULT;
103        if (!(params.mode & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR))) {
104            dev_dbg(pps->dev, "capture mode unspecified (%x)\n",
105                                params.mode);
106            return -EINVAL;
107        }
108
109        /* Check for supported capabilities */
110        if ((params.mode & ~pps->info.mode) != 0) {
111            dev_dbg(pps->dev, "unsupported capabilities (%x)\n",
112                                params.mode);
113            return -EINVAL;
114        }
115
116        spin_lock_irq(&pps->lock);
117
118        /* Save the new parameters */
119        pps->params = params;
120
121        /* Restore the read only parameters */
122        if ((params.mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
123            /* section 3.3 of RFC 2783 interpreted */
124            dev_dbg(pps->dev, "time format unspecified (%x)\n",
125                                params.mode);
126            pps->params.mode |= PPS_TSFMT_TSPEC;
127        }
128        if (pps->info.mode & PPS_CANWAIT)
129            pps->params.mode |= PPS_CANWAIT;
130        pps->params.api_version = PPS_API_VERS;
131
132        spin_unlock_irq(&pps->lock);
133
134        break;
135
136    case PPS_GETCAP:
137        dev_dbg(pps->dev, "PPS_GETCAP\n");
138
139        err = put_user(pps->info.mode, iuarg);
140        if (err)
141            return -EFAULT;
142
143        break;
144
145    case PPS_FETCH: {
146        struct pps_fdata fdata;
147        unsigned int ev;
148
149        dev_dbg(pps->dev, "PPS_FETCH\n");
150
151        err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
152        if (err)
153            return -EFAULT;
154
155        ev = pps->last_ev;
156
157        /* Manage the timeout */
158        if (fdata.timeout.flags & PPS_TIME_INVALID)
159            err = wait_event_interruptible(pps->queue,
160                    ev != pps->last_ev);
161        else {
162            unsigned long ticks;
163
164            dev_dbg(pps->dev, "timeout %lld.%09d\n",
165                    (long long) fdata.timeout.sec,
166                    fdata.timeout.nsec);
167            ticks = fdata.timeout.sec * HZ;
168            ticks += fdata.timeout.nsec / (NSEC_PER_SEC / HZ);
169
170            if (ticks != 0) {
171                err = wait_event_interruptible_timeout(
172                        pps->queue,
173                        ev != pps->last_ev,
174                        ticks);
175                if (err == 0)
176                    return -ETIMEDOUT;
177            }
178        }
179
180        /* Check for pending signals */
181        if (err == -ERESTARTSYS) {
182            dev_dbg(pps->dev, "pending signal caught\n");
183            return -EINTR;
184        }
185
186        /* Return the fetched timestamp */
187        spin_lock_irq(&pps->lock);
188
189        fdata.info.assert_sequence = pps->assert_sequence;
190        fdata.info.clear_sequence = pps->clear_sequence;
191        fdata.info.assert_tu = pps->assert_tu;
192        fdata.info.clear_tu = pps->clear_tu;
193        fdata.info.current_mode = pps->current_mode;
194
195        spin_unlock_irq(&pps->lock);
196
197        err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
198        if (err)
199            return -EFAULT;
200
201        break;
202    }
203    case PPS_KC_BIND: {
204        struct pps_bind_args bind_args;
205
206        dev_dbg(pps->dev, "PPS_KC_BIND\n");
207
208        /* Check the capabilities */
209        if (!capable(CAP_SYS_TIME))
210            return -EPERM;
211
212        if (copy_from_user(&bind_args, uarg,
213                    sizeof(struct pps_bind_args)))
214            return -EFAULT;
215
216        /* Check for supported capabilities */
217        if ((bind_args.edge & ~pps->info.mode) != 0) {
218            dev_err(pps->dev, "unsupported capabilities (%x)\n",
219                    bind_args.edge);
220            return -EINVAL;
221        }
222
223        /* Validate parameters roughly */
224        if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
225                (bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
226                bind_args.consumer != PPS_KC_HARDPPS) {
227            dev_err(pps->dev, "invalid kernel consumer bind"
228                    " parameters (%x)\n", bind_args.edge);
229            return -EINVAL;
230        }
231
232        err = pps_kc_bind(pps, &bind_args);
233        if (err < 0)
234            return err;
235
236        break;
237    }
238    default:
239        return -ENOTTY;
240    }
241
242    return 0;
243}
244
245static int pps_cdev_open(struct inode *inode, struct file *file)
246{
247    struct pps_device *pps = container_of(inode->i_cdev,
248                        struct pps_device, cdev);
249    file->private_data = pps;
250
251    return 0;
252}
253
254static int pps_cdev_release(struct inode *inode, struct file *file)
255{
256    return 0;
257}
258
259/*
260 * Char device stuff
261 */
262
263static const struct file_operations pps_cdev_fops = {
264    .owner = THIS_MODULE,
265    .llseek = no_llseek,
266    .poll = pps_cdev_poll,
267    .fasync = pps_cdev_fasync,
268    .unlocked_ioctl = pps_cdev_ioctl,
269    .open = pps_cdev_open,
270    .release = pps_cdev_release,
271};
272
273static void pps_device_destruct(struct device *dev)
274{
275    struct pps_device *pps = dev_get_drvdata(dev);
276
277    /* release id here to protect others from using it while it's
278     * still in use */
279    mutex_lock(&pps_idr_lock);
280    idr_remove(&pps_idr, pps->id);
281    mutex_unlock(&pps_idr_lock);
282
283    kfree(dev);
284    kfree(pps);
285}
286
287int pps_register_cdev(struct pps_device *pps)
288{
289    int err;
290    dev_t devt;
291
292    mutex_lock(&pps_idr_lock);
293    /* Get new ID for the new PPS source */
294    if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) {
295        mutex_unlock(&pps_idr_lock);
296        return -ENOMEM;
297    }
298
299    /* Now really allocate the PPS source.
300     * After idr_get_new() calling the new source will be freely available
301     * into the kernel.
302     */
303    err = idr_get_new(&pps_idr, pps, &pps->id);
304    mutex_unlock(&pps_idr_lock);
305
306    if (err < 0)
307        return err;
308
309    pps->id &= MAX_ID_MASK;
310    if (pps->id >= PPS_MAX_SOURCES) {
311        pr_err("%s: too many PPS sources in the system\n",
312                    pps->info.name);
313        err = -EBUSY;
314        goto free_idr;
315    }
316
317    devt = MKDEV(MAJOR(pps_devt), pps->id);
318
319    cdev_init(&pps->cdev, &pps_cdev_fops);
320    pps->cdev.owner = pps->info.owner;
321
322    err = cdev_add(&pps->cdev, devt, 1);
323    if (err) {
324        pr_err("%s: failed to add char device %d:%d\n",
325                pps->info.name, MAJOR(pps_devt), pps->id);
326        goto free_idr;
327    }
328    pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
329                            "pps%d", pps->id);
330    if (IS_ERR(pps->dev)) {
331        err = PTR_ERR(pps->dev);
332        goto del_cdev;
333    }
334
335    pps->dev->release = pps_device_destruct;
336
337    pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
338            MAJOR(pps_devt), pps->id);
339
340    return 0;
341
342del_cdev:
343    cdev_del(&pps->cdev);
344
345free_idr:
346    mutex_lock(&pps_idr_lock);
347    idr_remove(&pps_idr, pps->id);
348    mutex_unlock(&pps_idr_lock);
349
350    return err;
351}
352
353void pps_unregister_cdev(struct pps_device *pps)
354{
355    device_destroy(pps_class, pps->dev->devt);
356    cdev_del(&pps->cdev);
357}
358
359/*
360 * Module stuff
361 */
362
363static void __exit pps_exit(void)
364{
365    class_destroy(pps_class);
366    unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
367}
368
369static int __init pps_init(void)
370{
371    int err;
372
373    pps_class = class_create(THIS_MODULE, "pps");
374    if (IS_ERR(pps_class)) {
375        pr_err("failed to allocate class\n");
376        return PTR_ERR(pps_class);
377    }
378    pps_class->dev_attrs = pps_attrs;
379
380    err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
381    if (err < 0) {
382        pr_err("failed to allocate char device region\n");
383        goto remove_class;
384    }
385
386    pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
387    pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
388        "<giometti@linux.it>\n", PPS_VERSION);
389
390    return 0;
391
392remove_class:
393    class_destroy(pps_class);
394
395    return err;
396}
397
398subsys_initcall(pps_init);
399module_exit(pps_exit);
400
401MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
402MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
403MODULE_LICENSE("GPL");
404

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