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
42static dev_t ptp_devt;
43static struct class *ptp_class;
44
45static DECLARE_BITMAP(ptp_clocks_map, PTP_MAX_CLOCKS);
46static DEFINE_MUTEX(ptp_clocks_mutex); /* protects 'ptp_clocks_map' */
47
48/* time stamp event queue operations */
49
50static inline int queue_free(struct timestamp_event_queue *q)
51{
52	return PTP_MAX_TIMESTAMPS - queue_cnt(q) - 1;
53}
54
55static 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
80static 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
102static 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
109static 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
115static 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
121static 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
155static 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
167static 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
183struct 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
251no_clock:
252	if (ptp->pps_source)
253		pps_unregister_source(ptp->pps_source);
254no_pps:
255	ptp_cleanup_sysfs(ptp);
256no_sysfs:
257	device_destroy(ptp_class, ptp->devid);
258no_device:
259	mutex_destroy(&ptp->tsevq_mux);
260	kfree(ptp);
261no_memory:
262	clear_bit(index, ptp_clocks_map);
263no_slot:
264	mutex_unlock(&ptp_clocks_mutex);
265	return ERR_PTR(err);
266}
267EXPORT_SYMBOL(ptp_clock_register);
268
269int 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}
283EXPORT_SYMBOL(ptp_clock_unregister);
284
285void 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}
305EXPORT_SYMBOL(ptp_clock_event);
306
307/* module operations */
308
309static void __exit ptp_exit(void)
310{
311	class_destroy(ptp_class);
312	unregister_chrdev_region(ptp_devt, PTP_MAX_CLOCKS);
313}
314
315static 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
335no_region:
336	class_destroy(ptp_class);
337	return err;
338}
339
340subsys_initcall(ptp_init);
341module_exit(ptp_exit);
342
343MODULE_AUTHOR("Richard Cochran <richardcochran@gmail.com>");
344MODULE_DESCRIPTION("PTP clocks support");
345MODULE_LICENSE("GPL");
346