1 /*
2 * PTP 1588 clock support
3 *
4 * Copyright (C) 2010 OMICRON electronics GmbH
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 */
20 #include <linux/bitops.h>
21 #include <linux/device.h>
22 #include <linux/err.h>
23 #include <linux/init.h>
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/posix-clock.h>
27 #include <linux/pps_kernel.h>
28 #include <linux/slab.h>
29 #include <linux/syscalls.h>
30 #include <linux/uaccess.h>
31
32 #include "ptp_private.h"
33
34 #define PTP_MAX_ALARMS 4
35 #define PTP_MAX_CLOCKS 8
36 #define PTP_PPS_DEFAULTS (PPS_CAPTUREASSERT | PPS_OFFSETASSERT)
37 #define PTP_PPS_EVENT PPS_CAPTUREASSERT
38 #define PTP_PPS_MODE (PTP_PPS_DEFAULTS | PPS_CANWAIT | PPS_TSFMT_TSPEC)
39
40 /* private globals */
41
42 static dev_t ptp_devt;
43 static struct class *ptp_class;
44
45 static DECLARE_BITMAP(ptp_clocks_map, PTP_MAX_CLOCKS);
46 static DEFINE_MUTEX(ptp_clocks_mutex); /* protects 'ptp_clocks_map' */
47
48 /* time stamp event queue operations */
49
queue_free(struct timestamp_event_queue * q)50 static inline int queue_free(struct timestamp_event_queue *q)
51 {
52 return PTP_MAX_TIMESTAMPS - queue_cnt(q) - 1;
53 }
54
enqueue_external_timestamp(struct timestamp_event_queue * queue,struct ptp_clock_event * src)55 static void enqueue_external_timestamp(struct timestamp_event_queue *queue,
56 struct ptp_clock_event *src)
57 {
58 struct ptp_extts_event *dst;
59 unsigned long flags;
60 s64 seconds;
61 u32 remainder;
62
63 seconds = div_u64_rem(src->timestamp, 1000000000, &remainder);
64
65 spin_lock_irqsave(&queue->lock, flags);
66
67 dst = &queue->buf[queue->tail];
68 dst->index = src->index;
69 dst->t.sec = seconds;
70 dst->t.nsec = remainder;
71
72 if (!queue_free(queue))
73 queue->head = (queue->head + 1) % PTP_MAX_TIMESTAMPS;
74
75 queue->tail = (queue->tail + 1) % PTP_MAX_TIMESTAMPS;
76
77 spin_unlock_irqrestore(&queue->lock, flags);
78 }
79
scaled_ppm_to_ppb(long ppm)80 static s32 scaled_ppm_to_ppb(long ppm)
81 {
82 /*
83 * The 'freq' field in the 'struct timex' is in parts per
84 * million, but with a 16 bit binary fractional field.
85 *
86 * We want to calculate
87 *
88 * ppb = scaled_ppm * 1000 / 2^16
89 *
90 * which simplifies to
91 *
92 * ppb = scaled_ppm * 125 / 2^13
93 */
94 s64 ppb = 1 + ppm;
95 ppb *= 125;
96 ppb >>= 13;
97 return (s32) ppb;
98 }
99
100 /* posix clock implementation */
101
ptp_clock_getres(struct posix_clock * pc,struct timespec * tp)102 static int ptp_clock_getres(struct posix_clock *pc, struct timespec *tp)
103 {
104 tp->tv_sec = 0;
105 tp->tv_nsec = 1;
106 return 0;
107 }
108
ptp_clock_settime(struct posix_clock * pc,const struct timespec * tp)109 static int ptp_clock_settime(struct posix_clock *pc, const struct timespec *tp)
110 {
111 struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
112 return ptp->info->settime(ptp->info, tp);
113 }
114
ptp_clock_gettime(struct posix_clock * pc,struct timespec * tp)115 static int ptp_clock_gettime(struct posix_clock *pc, struct timespec *tp)
116 {
117 struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
118 return ptp->info->gettime(ptp->info, tp);
119 }
120
ptp_clock_adjtime(struct posix_clock * pc,struct timex * tx)121 static int ptp_clock_adjtime(struct posix_clock *pc, struct timex *tx)
122 {
123 struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
124 struct ptp_clock_info *ops;
125 int err = -EOPNOTSUPP;
126
127 ops = ptp->info;
128
129 if (tx->modes & ADJ_SETOFFSET) {
130 struct timespec ts;
131 ktime_t kt;
132 s64 delta;
133
134 ts.tv_sec = tx->time.tv_sec;
135 ts.tv_nsec = tx->time.tv_usec;
136
137 if (!(tx->modes & ADJ_NANO))
138 ts.tv_nsec *= 1000;
139
140 if ((unsigned long) ts.tv_nsec >= NSEC_PER_SEC)
141 return -EINVAL;
142
143 kt = timespec_to_ktime(ts);
144 delta = ktime_to_ns(kt);
145 err = ops->adjtime(ops, delta);
146
147 } else if (tx->modes & ADJ_FREQUENCY) {
148
149 err = ops->adjfreq(ops, scaled_ppm_to_ppb(tx->freq));
150 }
151
152 return err;
153 }
154
155 static struct posix_clock_operations ptp_clock_ops = {
156 .owner = THIS_MODULE,
157 .clock_adjtime = ptp_clock_adjtime,
158 .clock_gettime = ptp_clock_gettime,
159 .clock_getres = ptp_clock_getres,
160 .clock_settime = ptp_clock_settime,
161 .ioctl = ptp_ioctl,
162 .open = ptp_open,
163 .poll = ptp_poll,
164 .read = ptp_read,
165 };
166
delete_ptp_clock(struct posix_clock * pc)167 static void delete_ptp_clock(struct posix_clock *pc)
168 {
169 struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
170
171 mutex_destroy(&ptp->tsevq_mux);
172
173 /* Remove the clock from the bit map. */
174 mutex_lock(&ptp_clocks_mutex);
175 clear_bit(ptp->index, ptp_clocks_map);
176 mutex_unlock(&ptp_clocks_mutex);
177
178 kfree(ptp);
179 }
180
181 /* public interface */
182
ptp_clock_register(struct ptp_clock_info * info)183 struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info)
184 {
185 struct ptp_clock *ptp;
186 int err = 0, index, major = MAJOR(ptp_devt);
187
188 if (info->n_alarm > PTP_MAX_ALARMS)
189 return ERR_PTR(-EINVAL);
190
191 /* Find a free clock slot and reserve it. */
192 err = -EBUSY;
193 mutex_lock(&ptp_clocks_mutex);
194 index = find_first_zero_bit(ptp_clocks_map, PTP_MAX_CLOCKS);
195 if (index < PTP_MAX_CLOCKS)
196 set_bit(index, ptp_clocks_map);
197 else
198 goto no_slot;
199
200 /* Initialize a clock structure. */
201 err = -ENOMEM;
202 ptp = kzalloc(sizeof(struct ptp_clock), GFP_KERNEL);
203 if (ptp == NULL)
204 goto no_memory;
205
206 ptp->clock.ops = ptp_clock_ops;
207 ptp->clock.release = delete_ptp_clock;
208 ptp->info = info;
209 ptp->devid = MKDEV(major, index);
210 ptp->index = index;
211 spin_lock_init(&ptp->tsevq.lock);
212 mutex_init(&ptp->tsevq_mux);
213 init_waitqueue_head(&ptp->tsev_wq);
214
215 /* Create a new device in our class. */
216 ptp->dev = device_create(ptp_class, NULL, ptp->devid, ptp,
217 "ptp%d", ptp->index);
218 if (IS_ERR(ptp->dev))
219 goto no_device;
220
221 dev_set_drvdata(ptp->dev, ptp);
222
223 err = ptp_populate_sysfs(ptp);
224 if (err)
225 goto no_sysfs;
226
227 /* Register a new PPS source. */
228 if (info->pps) {
229 struct pps_source_info pps;
230 memset(&pps, 0, sizeof(pps));
231 snprintf(pps.name, PPS_MAX_NAME_LEN, "ptp%d", index);
232 pps.mode = PTP_PPS_MODE;
233 pps.owner = info->owner;
234 ptp->pps_source = pps_register_source(&pps, PTP_PPS_DEFAULTS);
235 if (!ptp->pps_source) {
236 pr_err("failed to register pps source\n");
237 goto no_pps;
238 }
239 }
240
241 /* Create a posix clock. */
242 err = posix_clock_register(&ptp->clock, ptp->devid);
243 if (err) {
244 pr_err("failed to create posix clock\n");
245 goto no_clock;
246 }
247
248 mutex_unlock(&ptp_clocks_mutex);
249 return ptp;
250
251 no_clock:
252 if (ptp->pps_source)
253 pps_unregister_source(ptp->pps_source);
254 no_pps:
255 ptp_cleanup_sysfs(ptp);
256 no_sysfs:
257 device_destroy(ptp_class, ptp->devid);
258 no_device:
259 mutex_destroy(&ptp->tsevq_mux);
260 kfree(ptp);
261 no_memory:
262 clear_bit(index, ptp_clocks_map);
263 no_slot:
264 mutex_unlock(&ptp_clocks_mutex);
265 return ERR_PTR(err);
266 }
267 EXPORT_SYMBOL(ptp_clock_register);
268
ptp_clock_unregister(struct ptp_clock * ptp)269 int ptp_clock_unregister(struct ptp_clock *ptp)
270 {
271 ptp->defunct = 1;
272 wake_up_interruptible(&ptp->tsev_wq);
273
274 /* Release the clock's resources. */
275 if (ptp->pps_source)
276 pps_unregister_source(ptp->pps_source);
277 ptp_cleanup_sysfs(ptp);
278 device_destroy(ptp_class, ptp->devid);
279
280 posix_clock_unregister(&ptp->clock);
281 return 0;
282 }
283 EXPORT_SYMBOL(ptp_clock_unregister);
284
ptp_clock_event(struct ptp_clock * ptp,struct ptp_clock_event * event)285 void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
286 {
287 struct pps_event_time evt;
288
289 switch (event->type) {
290
291 case PTP_CLOCK_ALARM:
292 break;
293
294 case PTP_CLOCK_EXTTS:
295 enqueue_external_timestamp(&ptp->tsevq, event);
296 wake_up_interruptible(&ptp->tsev_wq);
297 break;
298
299 case PTP_CLOCK_PPS:
300 pps_get_ts(&evt);
301 pps_event(ptp->pps_source, &evt, PTP_PPS_EVENT, NULL);
302 break;
303 }
304 }
305 EXPORT_SYMBOL(ptp_clock_event);
306
307 /* module operations */
308
ptp_exit(void)309 static void __exit ptp_exit(void)
310 {
311 class_destroy(ptp_class);
312 unregister_chrdev_region(ptp_devt, PTP_MAX_CLOCKS);
313 }
314
ptp_init(void)315 static int __init ptp_init(void)
316 {
317 int err;
318
319 ptp_class = class_create(THIS_MODULE, "ptp");
320 if (IS_ERR(ptp_class)) {
321 pr_err("ptp: failed to allocate class\n");
322 return PTR_ERR(ptp_class);
323 }
324
325 err = alloc_chrdev_region(&ptp_devt, 0, PTP_MAX_CLOCKS, "ptp");
326 if (err < 0) {
327 pr_err("ptp: failed to allocate device region\n");
328 goto no_region;
329 }
330
331 ptp_class->dev_attrs = ptp_dev_attrs;
332 pr_info("PTP clock support registered\n");
333 return 0;
334
335 no_region:
336 class_destroy(ptp_class);
337 return err;
338 }
339
340 subsys_initcall(ptp_init);
341 module_exit(ptp_exit);
342
343 MODULE_AUTHOR("Richard Cochran <richardcochran@gmail.com>");
344 MODULE_DESCRIPTION("PTP clocks support");
345 MODULE_LICENSE("GPL");
346