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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2015-2017 Pengutronix, Uwe Kleine-König <kernel@pengutronix.de>
4 */
5#include <linux/kernel.h>
6#include <linux/device.h>
7#include <linux/module.h>
8#include <linux/slab.h>
9#include <linux/sysfs.h>
10
11#include "siox.h"
12
13/*
14 * The lowest bit in the SIOX status word signals if the in-device watchdog is
15 * ok. If the bit is set, the device is functional.
16 *
17 * On writing the watchdog timer is reset when this bit toggles.
18 */
19#define SIOX_STATUS_WDG 0x01
20
21/*
22 * Bits 1 to 3 of the status word read as the bitwise negation of what was
23 * clocked in before. The value clocked in is changed in each cycle and so
24 * allows to detect transmit/receive problems.
25 */
26#define SIOX_STATUS_COUNTER 0x0e
27
28/*
29 * Each Siox-Device has a 4 bit type number that is neither 0 nor 15. This is
30 * available in the upper nibble of the read status.
31 *
32 * On write these bits are DC.
33 */
34#define SIOX_STATUS_TYPE 0xf0
35
36#define CREATE_TRACE_POINTS
37#include <trace/events/siox.h>
38
39static bool siox_is_registered;
40
41static void siox_master_lock(struct siox_master *smaster)
42{
43 mutex_lock(&smaster->lock);
44}
45
46static void siox_master_unlock(struct siox_master *smaster)
47{
48 mutex_unlock(&smaster->lock);
49}
50
51static inline u8 siox_status_clean(u8 status_read, u8 status_written)
52{
53 /*
54 * bits 3:1 of status sample the respective bit in the status
55 * byte written in the previous cycle but inverted. So if you wrote the
56 * status word as 0xa before (counter = 0b101), it is expected to get
57 * back the counter bits as 0b010.
58 *
59 * So given the last status written this function toggles the there
60 * unset counter bits in the read value such that the counter bits in
61 * the return value are all zero iff the bits were read as expected to
62 * simplify error detection.
63 */
64
65 return status_read ^ (~status_written & 0xe);
66}
67
68static bool siox_device_counter_error(struct siox_device *sdevice,
69 u8 status_clean)
70{
71 return (status_clean & SIOX_STATUS_COUNTER) != 0;
72}
73
74static bool siox_device_type_error(struct siox_device *sdevice, u8 status_clean)
75{
76 u8 statustype = (status_clean & SIOX_STATUS_TYPE) >> 4;
77
78 /*
79 * If the device knows which value the type bits should have, check
80 * against this value otherwise just rule out the invalid values 0b0000
81 * and 0b1111.
82 */
83 if (sdevice->statustype) {
84 if (statustype != sdevice->statustype)
85 return true;
86 } else {
87 switch (statustype) {
88 case 0:
89 case 0xf:
90 return true;
91 }
92 }
93
94 return false;
95}
96
97static bool siox_device_wdg_error(struct siox_device *sdevice, u8 status_clean)
98{
99 return (status_clean & SIOX_STATUS_WDG) == 0;
100}
101
102/*
103 * If there is a type or counter error the device is called "unsynced".
104 */
105bool siox_device_synced(struct siox_device *sdevice)
106{
107 if (siox_device_type_error(sdevice, sdevice->status_read_clean))
108 return false;
109
110 return !siox_device_counter_error(sdevice, sdevice->status_read_clean);
111
112}
113EXPORT_SYMBOL_GPL(siox_device_synced);
114
115/*
116 * A device is called "connected" if it is synced and the watchdog is not
117 * asserted.
118 */
119bool siox_device_connected(struct siox_device *sdevice)
120{
121 if (!siox_device_synced(sdevice))
122 return false;
123
124 return !siox_device_wdg_error(sdevice, sdevice->status_read_clean);
125}
126EXPORT_SYMBOL_GPL(siox_device_connected);
127
128static void siox_poll(struct siox_master *smaster)
129{
130 struct siox_device *sdevice;
131 size_t i = smaster->setbuf_len;
132 unsigned int devno = 0;
133 int unsync_error = 0;
134
135 smaster->last_poll = jiffies;
136
137 /*
138 * The counter bits change in each second cycle, the watchdog bit
139 * toggles each time.
140 * The counter bits hold values from [0, 6]. 7 would be possible
141 * theoretically but the protocol designer considered that a bad idea
142 * for reasons unknown today. (Maybe that's because then the status read
143 * back has only zeros in the counter bits then which might be confused
144 * with a stuck-at-0 error. But for the same reason (with s/0/1/) 0
145 * could be skipped.)
146 */
147 if (++smaster->status > 0x0d)
148 smaster->status = 0;
149
150 memset(smaster->buf, 0, smaster->setbuf_len);
151
152 /* prepare data pushed out to devices in buf[0..setbuf_len) */
153 list_for_each_entry(sdevice, &smaster->devices, node) {
154 struct siox_driver *sdriver =
155 to_siox_driver(sdevice->dev.driver);
156 sdevice->status_written = smaster->status;
157
158 i -= sdevice->inbytes;
159
160 /*
161 * If the device or a previous one is unsynced, don't pet the
162 * watchdog. This is done to ensure that the device is kept in
163 * reset when something is wrong.
164 */
165 if (!siox_device_synced(sdevice))
166 unsync_error = 1;
167
168 if (sdriver && !unsync_error)
169 sdriver->set_data(sdevice, sdevice->status_written,
170 &smaster->buf[i + 1]);
171 else
172 /*
173 * Don't trigger watchdog if there is no driver or a
174 * sync problem
175 */
176 sdevice->status_written &= ~SIOX_STATUS_WDG;
177
178 smaster->buf[i] = sdevice->status_written;
179
180 trace_siox_set_data(smaster, sdevice, devno, i);
181
182 devno++;
183 }
184
185 smaster->pushpull(smaster, smaster->setbuf_len, smaster->buf,
186 smaster->getbuf_len,
187 smaster->buf + smaster->setbuf_len);
188
189 unsync_error = 0;
190
191 /* interpret data pulled in from devices in buf[setbuf_len..] */
192 devno = 0;
193 i = smaster->setbuf_len;
194 list_for_each_entry(sdevice, &smaster->devices, node) {
195 struct siox_driver *sdriver =
196 to_siox_driver(sdevice->dev.driver);
197 u8 status = smaster->buf[i + sdevice->outbytes - 1];
198 u8 status_clean;
199 u8 prev_status_clean = sdevice->status_read_clean;
200 bool synced = true;
201 bool connected = true;
202
203 if (!siox_device_synced(sdevice))
204 unsync_error = 1;
205
206 /*
207 * If the watchdog bit wasn't toggled in this cycle, report the
208 * watchdog as active to give a consistent view for drivers and
209 * sysfs consumers.
210 */
211 if (!sdriver || unsync_error)
212 status &= ~SIOX_STATUS_WDG;
213
214 status_clean =
215 siox_status_clean(status,
216 sdevice->status_written_lastcycle);
217
218 /* Check counter and type bits */
219 if (siox_device_counter_error(sdevice, status_clean) ||
220 siox_device_type_error(sdevice, status_clean)) {
221 bool prev_error;
222
223 synced = false;
224
225 /* only report a new error if the last cycle was ok */
226 prev_error =
227 siox_device_counter_error(sdevice,
228 prev_status_clean) ||
229 siox_device_type_error(sdevice,
230 prev_status_clean);
231
232 if (!prev_error) {
233 sdevice->status_errors++;
234 sysfs_notify_dirent(sdevice->status_errors_kn);
235 }
236 }
237
238 /* If the device is unsynced report the watchdog as active */
239 if (!synced) {
240 status &= ~SIOX_STATUS_WDG;
241 status_clean &= ~SIOX_STATUS_WDG;
242 }
243
244 if (siox_device_wdg_error(sdevice, status_clean))
245 connected = false;
246
247 /* The watchdog state changed just now */
248 if ((status_clean ^ prev_status_clean) & SIOX_STATUS_WDG) {
249 sysfs_notify_dirent(sdevice->watchdog_kn);
250
251 if (siox_device_wdg_error(sdevice, status_clean)) {
252 struct kernfs_node *wd_errs =
253 sdevice->watchdog_errors_kn;
254
255 sdevice->watchdog_errors++;
256 sysfs_notify_dirent(wd_errs);
257 }
258 }
259
260 if (connected != sdevice->connected)
261 sysfs_notify_dirent(sdevice->connected_kn);
262
263 sdevice->status_read_clean = status_clean;
264 sdevice->status_written_lastcycle = sdevice->status_written;
265 sdevice->connected = connected;
266
267 trace_siox_get_data(smaster, sdevice, devno, status_clean, i);
268
269 /* only give data read to driver if the device is connected */
270 if (sdriver && connected)
271 sdriver->get_data(sdevice, &smaster->buf[i]);
272
273 devno++;
274 i += sdevice->outbytes;
275 }
276}
277
278static int siox_poll_thread(void *data)
279{
280 struct siox_master *smaster = data;
281 signed long timeout = 0;
282
283 get_device(&smaster->dev);
284
285 for (;;) {
286 if (kthread_should_stop()) {
287 put_device(&smaster->dev);
288 return 0;
289 }
290
291 siox_master_lock(smaster);
292
293 if (smaster->active) {
294 unsigned long next_poll =
295 smaster->last_poll + smaster->poll_interval;
296 if (time_is_before_eq_jiffies(next_poll))
297 siox_poll(smaster);
298
299 timeout = smaster->poll_interval -
300 (jiffies - smaster->last_poll);
301 } else {
302 timeout = MAX_SCHEDULE_TIMEOUT;
303 }
304
305 /*
306 * Set the task to idle while holding the lock. This makes sure
307 * that we don't sleep too long when the bus is reenabled before
308 * schedule_timeout is reached.
309 */
310 if (timeout > 0)
311 set_current_state(TASK_IDLE);
312
313 siox_master_unlock(smaster);
314
315 if (timeout > 0)
316 schedule_timeout(timeout);
317
318 /*
319 * I'm not clear if/why it is important to set the state to
320 * RUNNING again, but it fixes a "do not call blocking ops when
321 * !TASK_RUNNING;"-warning.
322 */
323 set_current_state(TASK_RUNNING);
324 }
325}
326
327static int __siox_start(struct siox_master *smaster)
328{
329 if (!(smaster->setbuf_len + smaster->getbuf_len))
330 return -ENODEV;
331
332 if (!smaster->buf)
333 return -ENOMEM;
334
335 if (smaster->active)
336 return 0;
337
338 smaster->active = 1;
339 wake_up_process(smaster->poll_thread);
340
341 return 1;
342}
343
344static int siox_start(struct siox_master *smaster)
345{
346 int ret;
347
348 siox_master_lock(smaster);
349 ret = __siox_start(smaster);
350 siox_master_unlock(smaster);
351
352 return ret;
353}
354
355static int __siox_stop(struct siox_master *smaster)
356{
357 if (smaster->active) {
358 struct siox_device *sdevice;
359
360 smaster->active = 0;
361
362 list_for_each_entry(sdevice, &smaster->devices, node) {
363 if (sdevice->connected)
364 sysfs_notify_dirent(sdevice->connected_kn);
365 sdevice->connected = false;
366 }
367
368 return 1;
369 }
370 return 0;
371}
372
373static int siox_stop(struct siox_master *smaster)
374{
375 int ret;
376
377 siox_master_lock(smaster);
378 ret = __siox_stop(smaster);
379 siox_master_unlock(smaster);
380
381 return ret;
382}
383
384static ssize_t type_show(struct device *dev,
385 struct device_attribute *attr, char *buf)
386{
387 struct siox_device *sdev = to_siox_device(dev);
388
389 return sprintf(buf, "%s\n", sdev->type);
390}
391
392static DEVICE_ATTR_RO(type);
393
394static ssize_t inbytes_show(struct device *dev,
395 struct device_attribute *attr, char *buf)
396{
397 struct siox_device *sdev = to_siox_device(dev);
398
399 return sprintf(buf, "%zu\n", sdev->inbytes);
400}
401
402static DEVICE_ATTR_RO(inbytes);
403
404static ssize_t outbytes_show(struct device *dev,
405 struct device_attribute *attr, char *buf)
406{
407 struct siox_device *sdev = to_siox_device(dev);
408
409 return sprintf(buf, "%zu\n", sdev->outbytes);
410}
411
412static DEVICE_ATTR_RO(outbytes);
413
414static ssize_t status_errors_show(struct device *dev,
415 struct device_attribute *attr, char *buf)
416{
417 struct siox_device *sdev = to_siox_device(dev);
418 unsigned int status_errors;
419
420 siox_master_lock(sdev->smaster);
421
422 status_errors = sdev->status_errors;
423
424 siox_master_unlock(sdev->smaster);
425
426 return sprintf(buf, "%u\n", status_errors);
427}
428
429static DEVICE_ATTR_RO(status_errors);
430
431static ssize_t connected_show(struct device *dev,
432 struct device_attribute *attr, char *buf)
433{
434 struct siox_device *sdev = to_siox_device(dev);
435 bool connected;
436
437 siox_master_lock(sdev->smaster);
438
439 connected = sdev->connected;
440
441 siox_master_unlock(sdev->smaster);
442
443 return sprintf(buf, "%u\n", connected);
444}
445
446static DEVICE_ATTR_RO(connected);
447
448static ssize_t watchdog_show(struct device *dev,
449 struct device_attribute *attr, char *buf)
450{
451 struct siox_device *sdev = to_siox_device(dev);
452 u8 status;
453
454 siox_master_lock(sdev->smaster);
455
456 status = sdev->status_read_clean;
457
458 siox_master_unlock(sdev->smaster);
459
460 return sprintf(buf, "%d\n", status & SIOX_STATUS_WDG);
461}
462
463static DEVICE_ATTR_RO(watchdog);
464
465static ssize_t watchdog_errors_show(struct device *dev,
466 struct device_attribute *attr, char *buf)
467{
468 struct siox_device *sdev = to_siox_device(dev);
469 unsigned int watchdog_errors;
470
471 siox_master_lock(sdev->smaster);
472
473 watchdog_errors = sdev->watchdog_errors;
474
475 siox_master_unlock(sdev->smaster);
476
477 return sprintf(buf, "%u\n", watchdog_errors);
478}
479
480static DEVICE_ATTR_RO(watchdog_errors);
481
482static struct attribute *siox_device_attrs[] = {
483 &dev_attr_type.attr,
484 &dev_attr_inbytes.attr,
485 &dev_attr_outbytes.attr,
486 &dev_attr_status_errors.attr,
487 &dev_attr_connected.attr,
488 &dev_attr_watchdog.attr,
489 &dev_attr_watchdog_errors.attr,
490 NULL
491};
492ATTRIBUTE_GROUPS(siox_device);
493
494static void siox_device_release(struct device *dev)
495{
496 struct siox_device *sdevice = to_siox_device(dev);
497
498 kfree(sdevice);
499}
500
501static struct device_type siox_device_type = {
502 .groups = siox_device_groups,
503 .release = siox_device_release,
504};
505
506static int siox_match(struct device *dev, struct device_driver *drv)
507{
508 if (dev->type != &siox_device_type)
509 return 0;
510
511 /* up to now there is only a single driver so keeping this simple */
512 return 1;
513}
514
515static int siox_probe(struct device *dev)
516{
517 struct siox_driver *sdriver = to_siox_driver(dev->driver);
518 struct siox_device *sdevice = to_siox_device(dev);
519
520 return sdriver->probe(sdevice);
521}
522
523static void siox_remove(struct device *dev)
524{
525 struct siox_driver *sdriver =
526 container_of(dev->driver, struct siox_driver, driver);
527 struct siox_device *sdevice = to_siox_device(dev);
528
529 if (sdriver->remove)
530 sdriver->remove(sdevice);
531}
532
533static void siox_shutdown(struct device *dev)
534{
535 struct siox_device *sdevice = to_siox_device(dev);
536 struct siox_driver *sdriver;
537
538 if (!dev->driver)
539 return;
540
541 sdriver = container_of(dev->driver, struct siox_driver, driver);
542 if (sdriver->shutdown)
543 sdriver->shutdown(sdevice);
544}
545
546static struct bus_type siox_bus_type = {
547 .name = "siox",
548 .match = siox_match,
549 .probe = siox_probe,
550 .remove = siox_remove,
551 .shutdown = siox_shutdown,
552};
553
554static ssize_t active_show(struct device *dev,
555 struct device_attribute *attr, char *buf)
556{
557 struct siox_master *smaster = to_siox_master(dev);
558
559 return sprintf(buf, "%d\n", smaster->active);
560}
561
562static ssize_t active_store(struct device *dev,
563 struct device_attribute *attr,
564 const char *buf, size_t count)
565{
566 struct siox_master *smaster = to_siox_master(dev);
567 int ret;
568 int active;
569
570 ret = kstrtoint(buf, 0, &active);
571 if (ret < 0)
572 return ret;
573
574 if (active)
575 ret = siox_start(smaster);
576 else
577 ret = siox_stop(smaster);
578
579 if (ret < 0)
580 return ret;
581
582 return count;
583}
584
585static DEVICE_ATTR_RW(active);
586
587static struct siox_device *siox_device_add(struct siox_master *smaster,
588 const char *type, size_t inbytes,
589 size_t outbytes, u8 statustype);
590
591static ssize_t device_add_store(struct device *dev,
592 struct device_attribute *attr,
593 const char *buf, size_t count)
594{
595 struct siox_master *smaster = to_siox_master(dev);
596 int ret;
597 char type[20] = "";
598 size_t inbytes = 0, outbytes = 0;
599 u8 statustype = 0;
600
601 ret = sscanf(buf, "%19s %zu %zu %hhu", type, &inbytes,
602 &outbytes, &statustype);
603 if (ret != 3 && ret != 4)
604 return -EINVAL;
605
606 if (strcmp(type, "siox-12x8") || inbytes != 2 || outbytes != 4)
607 return -EINVAL;
608
609 siox_device_add(smaster, "siox-12x8", inbytes, outbytes, statustype);
610
611 return count;
612}
613
614static DEVICE_ATTR_WO(device_add);
615
616static void siox_device_remove(struct siox_master *smaster);
617
618static ssize_t device_remove_store(struct device *dev,
619 struct device_attribute *attr,
620 const char *buf, size_t count)
621{
622 struct siox_master *smaster = to_siox_master(dev);
623
624 /* XXX? require to write <type> <inbytes> <outbytes> */
625 siox_device_remove(smaster);
626
627 return count;
628}
629
630static DEVICE_ATTR_WO(device_remove);
631
632static ssize_t poll_interval_ns_show(struct device *dev,
633 struct device_attribute *attr, char *buf)
634{
635 struct siox_master *smaster = to_siox_master(dev);
636
637 return sprintf(buf, "%lld\n", jiffies_to_nsecs(smaster->poll_interval));
638}
639
640static ssize_t poll_interval_ns_store(struct device *dev,
641 struct device_attribute *attr,
642 const char *buf, size_t count)
643{
644 struct siox_master *smaster = to_siox_master(dev);
645 int ret;
646 u64 val;
647
648 ret = kstrtou64(buf, 0, &val);
649 if (ret < 0)
650 return ret;
651
652 siox_master_lock(smaster);
653
654 smaster->poll_interval = nsecs_to_jiffies(val);
655
656 siox_master_unlock(smaster);
657
658 return count;
659}
660
661static DEVICE_ATTR_RW(poll_interval_ns);
662
663static struct attribute *siox_master_attrs[] = {
664 &dev_attr_active.attr,
665 &dev_attr_device_add.attr,
666 &dev_attr_device_remove.attr,
667 &dev_attr_poll_interval_ns.attr,
668 NULL
669};
670ATTRIBUTE_GROUPS(siox_master);
671
672static void siox_master_release(struct device *dev)
673{
674 struct siox_master *smaster = to_siox_master(dev);
675
676 kfree(smaster);
677}
678
679static struct device_type siox_master_type = {
680 .groups = siox_master_groups,
681 .release = siox_master_release,
682};
683
684struct siox_master *siox_master_alloc(struct device *dev,
685 size_t size)
686{
687 struct siox_master *smaster;
688
689 if (!dev)
690 return NULL;
691
692 smaster = kzalloc(sizeof(*smaster) + size, GFP_KERNEL);
693 if (!smaster)
694 return NULL;
695
696 device_initialize(&smaster->dev);
697
698 smaster->busno = -1;
699 smaster->dev.bus = &siox_bus_type;
700 smaster->dev.type = &siox_master_type;
701 smaster->dev.parent = dev;
702 smaster->poll_interval = DIV_ROUND_UP(HZ, 40);
703
704 dev_set_drvdata(&smaster->dev, &smaster[1]);
705
706 return smaster;
707}
708EXPORT_SYMBOL_GPL(siox_master_alloc);
709
710int siox_master_register(struct siox_master *smaster)
711{
712 int ret;
713
714 if (!siox_is_registered)
715 return -EPROBE_DEFER;
716
717 if (!smaster->pushpull)
718 return -EINVAL;
719
720 dev_set_name(&smaster->dev, "siox-%d", smaster->busno);
721
722 mutex_init(&smaster->lock);
723 INIT_LIST_HEAD(&smaster->devices);
724
725 smaster->last_poll = jiffies;
726 smaster->poll_thread = kthread_run(siox_poll_thread, smaster,
727 "siox-%d", smaster->busno);
728 if (IS_ERR(smaster->poll_thread)) {
729 smaster->active = 0;
730 return PTR_ERR(smaster->poll_thread);
731 }
732
733 ret = device_add(&smaster->dev);
734 if (ret)
735 kthread_stop(smaster->poll_thread);
736
737 return ret;
738}
739EXPORT_SYMBOL_GPL(siox_master_register);
740
741void siox_master_unregister(struct siox_master *smaster)
742{
743 /* remove device */
744 device_del(&smaster->dev);
745
746 siox_master_lock(smaster);
747
748 __siox_stop(smaster);
749
750 while (smaster->num_devices) {
751 struct siox_device *sdevice;
752
753 sdevice = container_of(smaster->devices.prev,
754 struct siox_device, node);
755 list_del(&sdevice->node);
756 smaster->num_devices--;
757
758 siox_master_unlock(smaster);
759
760 device_unregister(&sdevice->dev);
761
762 siox_master_lock(smaster);
763 }
764
765 siox_master_unlock(smaster);
766
767 put_device(&smaster->dev);
768}
769EXPORT_SYMBOL_GPL(siox_master_unregister);
770
771static struct siox_device *siox_device_add(struct siox_master *smaster,
772 const char *type, size_t inbytes,
773 size_t outbytes, u8 statustype)
774{
775 struct siox_device *sdevice;
776 int ret;
777 size_t buf_len;
778
779 sdevice = kzalloc(sizeof(*sdevice), GFP_KERNEL);
780 if (!sdevice)
781 return ERR_PTR(-ENOMEM);
782
783 sdevice->type = type;
784 sdevice->inbytes = inbytes;
785 sdevice->outbytes = outbytes;
786 sdevice->statustype = statustype;
787
788 sdevice->smaster = smaster;
789 sdevice->dev.parent = &smaster->dev;
790 sdevice->dev.bus = &siox_bus_type;
791 sdevice->dev.type = &siox_device_type;
792
793 siox_master_lock(smaster);
794
795 dev_set_name(&sdevice->dev, "siox-%d-%d",
796 smaster->busno, smaster->num_devices);
797
798 buf_len = smaster->setbuf_len + inbytes +
799 smaster->getbuf_len + outbytes;
800 if (smaster->buf_len < buf_len) {
801 u8 *buf = krealloc(smaster->buf, buf_len, GFP_KERNEL);
802
803 if (!buf) {
804 dev_err(&smaster->dev,
805 "failed to realloc buffer to %zu\n", buf_len);
806 ret = -ENOMEM;
807 goto err_buf_alloc;
808 }
809
810 smaster->buf_len = buf_len;
811 smaster->buf = buf;
812 }
813
814 ret = device_register(&sdevice->dev);
815 if (ret) {
816 dev_err(&smaster->dev, "failed to register device: %d\n", ret);
817
818 goto err_device_register;
819 }
820
821 smaster->num_devices++;
822 list_add_tail(&sdevice->node, &smaster->devices);
823
824 smaster->setbuf_len += sdevice->inbytes;
825 smaster->getbuf_len += sdevice->outbytes;
826
827 sdevice->status_errors_kn = sysfs_get_dirent(sdevice->dev.kobj.sd,
828 "status_errors");
829 sdevice->watchdog_kn = sysfs_get_dirent(sdevice->dev.kobj.sd,
830 "watchdog");
831 sdevice->watchdog_errors_kn = sysfs_get_dirent(sdevice->dev.kobj.sd,
832 "watchdog_errors");
833 sdevice->connected_kn = sysfs_get_dirent(sdevice->dev.kobj.sd,
834 "connected");
835
836 siox_master_unlock(smaster);
837
838 return sdevice;
839
840err_device_register:
841 /* don't care to make the buffer smaller again */
842 put_device(&sdevice->dev);
843 sdevice = NULL;
844
845err_buf_alloc:
846 siox_master_unlock(smaster);
847
848 kfree(sdevice);
849
850 return ERR_PTR(ret);
851}
852
853static void siox_device_remove(struct siox_master *smaster)
854{
855 struct siox_device *sdevice;
856
857 siox_master_lock(smaster);
858
859 if (!smaster->num_devices) {
860 siox_master_unlock(smaster);
861 return;
862 }
863
864 sdevice = container_of(smaster->devices.prev, struct siox_device, node);
865 list_del(&sdevice->node);
866 smaster->num_devices--;
867
868 smaster->setbuf_len -= sdevice->inbytes;
869 smaster->getbuf_len -= sdevice->outbytes;
870
871 if (!smaster->num_devices)
872 __siox_stop(smaster);
873
874 siox_master_unlock(smaster);
875
876 /*
877 * This must be done without holding the master lock because we're
878 * called from device_remove_store which also holds a sysfs mutex.
879 * device_unregister tries to aquire the same lock.
880 */
881 device_unregister(&sdevice->dev);
882}
883
884int __siox_driver_register(struct siox_driver *sdriver, struct module *owner)
885{
886 int ret;
887
888 if (unlikely(!siox_is_registered))
889 return -EPROBE_DEFER;
890
891 if (!sdriver->probe ||
892 (!sdriver->set_data && !sdriver->get_data)) {
893 pr_err("Driver %s doesn't provide needed callbacks\n",
894 sdriver->driver.name);
895 return -EINVAL;
896 }
897
898 sdriver->driver.owner = owner;
899 sdriver->driver.bus = &siox_bus_type;
900
901 ret = driver_register(&sdriver->driver);
902 if (ret)
903 pr_err("Failed to register siox driver %s (%d)\n",
904 sdriver->driver.name, ret);
905
906 return ret;
907}
908EXPORT_SYMBOL_GPL(__siox_driver_register);
909
910static int __init siox_init(void)
911{
912 int ret;
913
914 ret = bus_register(&siox_bus_type);
915 if (ret) {
916 pr_err("Registration of SIOX bus type failed: %d\n", ret);
917 return ret;
918 }
919
920 siox_is_registered = true;
921
922 return 0;
923}
924subsys_initcall(siox_init);
925
926static void __exit siox_exit(void)
927{
928 bus_unregister(&siox_bus_type);
929}
930module_exit(siox_exit);
931
932MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>");
933MODULE_DESCRIPTION("Eckelmann SIOX driver core");
934MODULE_LICENSE("GPL v2");