blob: ea6633eab3b15ba691c77799c9f1e661c502ee96 [file] [log] [blame]
lh9ed821d2023-04-07 01:36:19 -07001/*
2 * SPI init/core code
3 *
4 * Copyright (C) 2005 David Brownell
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
21#include <linux/kernel.h>
22#include <linux/device.h>
23#include <linux/init.h>
24#include <linux/cache.h>
25#include <linux/mutex.h>
26#include <linux/of_device.h>
27#include <linux/slab.h>
28#include <linux/mod_devicetable.h>
29#include <linux/spi/spi.h>
30#include <linux/of_spi.h>
31#include <linux/pm_runtime.h>
32#include <linux/export.h>
33#include <linux/sched.h>
34#include <linux/delay.h>
35#include <linux/kthread.h>
36
37static void spidev_release(struct device *dev)
38{
39 struct spi_device *spi = to_spi_device(dev);
40
41 if (!dev)
42 return;
43
44 /* spi masters may cleanup for released devices */
45 if (spi->master->cleanup)
46 spi->master->cleanup(spi);
47
48 spi_master_put(spi->master);
49 kfree(spi);
50}
51
52static ssize_t
53modalias_show(struct device *dev, struct device_attribute *a, char *buf)
54{
55 const struct spi_device *spi = to_spi_device(dev);
56
57 return sprintf(buf, "%s\n", spi->modalias);
58}
59
60static struct device_attribute spi_dev_attrs[] = {
61 __ATTR_RO(modalias),
62 __ATTR_NULL,
63};
64
65/* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
66 * and the sysfs version makes coldplug work too.
67 */
68
69static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
70 const struct spi_device *sdev)
71{
72 while (id->name[0]) {
73 if (!strcmp(sdev->modalias, id->name))
74 return id;
75 id++;
76 }
77 return NULL;
78}
79
80const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
81{
82 const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
83
84#ifdef CONFIG_KLOCWORK
85 if (!sdrv)
86 return NULL;
87#endif
88
89 return spi_match_id(sdrv->id_table, sdev);
90}
91EXPORT_SYMBOL_GPL(spi_get_device_id);
92
93static int spi_match_device(struct device *dev, struct device_driver *drv)
94{
95 const struct spi_device *spi = to_spi_device(dev);
96 const struct spi_driver *sdrv = to_spi_driver(drv);
97
98 /* Attempt an OF style match */
99 if (of_driver_match_device(dev, drv))
100 return 1;
101
102#ifdef CONFIG_KLOCWORK
103 if (!dev || !drv)
104 return -ENODEV;
105#endif
106
107 if (sdrv->id_table)
108 return !!spi_match_id(sdrv->id_table, spi);
109
110 return strcmp(spi->modalias, drv->name) == 0;
111}
112
113static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
114{
115 const struct spi_device *spi = to_spi_device(dev);
116
117 add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
118 return 0;
119}
120
121#ifdef CONFIG_PM_SLEEP
122static int spi_legacy_suspend(struct device *dev, pm_message_t message)
123{
124 int value = 0;
125 struct spi_driver *drv = to_spi_driver(dev->driver);
126
127 /* suspend will stop irqs and dma; no more i/o */
128 if (drv) {
129 if (drv->suspend)
130 value = drv->suspend(to_spi_device(dev), message);
131 else
132 dev_dbg(dev, "... can't suspend\n");
133 }
134 return value;
135}
136
137static int spi_legacy_resume(struct device *dev)
138{
139 int value = 0;
140 struct spi_driver *drv = to_spi_driver(dev->driver);
141
142 /* resume may restart the i/o queue */
143 if (drv) {
144 if (drv->resume)
145 value = drv->resume(to_spi_device(dev));
146 else
147 dev_dbg(dev, "... can't resume\n");
148 }
149 return value;
150}
151
152static int spi_pm_suspend(struct device *dev)
153{
154 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
155
156 if (pm)
157 return pm_generic_suspend(dev);
158 else
159 return spi_legacy_suspend(dev, PMSG_SUSPEND);
160}
161
162static int spi_pm_resume(struct device *dev)
163{
164 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
165
166 if (pm)
167 return pm_generic_resume(dev);
168 else
169 return spi_legacy_resume(dev);
170}
171
172static int spi_pm_freeze(struct device *dev)
173{
174 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
175
176 if (pm)
177 return pm_generic_freeze(dev);
178 else
179 return spi_legacy_suspend(dev, PMSG_FREEZE);
180}
181
182static int spi_pm_thaw(struct device *dev)
183{
184 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
185
186 if (pm)
187 return pm_generic_thaw(dev);
188 else
189 return spi_legacy_resume(dev);
190}
191
192static int spi_pm_poweroff(struct device *dev)
193{
194 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
195
196 if (pm)
197 return pm_generic_poweroff(dev);
198 else
199 return spi_legacy_suspend(dev, PMSG_HIBERNATE);
200}
201
202static int spi_pm_restore(struct device *dev)
203{
204 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
205
206 if (pm)
207 return pm_generic_restore(dev);
208 else
209 return spi_legacy_resume(dev);
210}
211#else
212#define spi_pm_suspend NULL
213#define spi_pm_resume NULL
214#define spi_pm_freeze NULL
215#define spi_pm_thaw NULL
216#define spi_pm_poweroff NULL
217#define spi_pm_restore NULL
218#endif
219
220static const struct dev_pm_ops spi_pm = {
221 .suspend = spi_pm_suspend,
222 .resume = spi_pm_resume,
223 .freeze = spi_pm_freeze,
224 .thaw = spi_pm_thaw,
225 .poweroff = spi_pm_poweroff,
226 .restore = spi_pm_restore,
227 SET_RUNTIME_PM_OPS(
228 pm_generic_runtime_suspend,
229 pm_generic_runtime_resume,
230 pm_generic_runtime_idle
231 )
232};
233
234struct bus_type spi_bus_type = {
235 .name = "spi",
236 .dev_attrs = spi_dev_attrs,
237 .match = spi_match_device,
238 .uevent = spi_uevent,
239 .pm = &spi_pm,
240};
241EXPORT_SYMBOL_GPL(spi_bus_type);
242
243
244static int spi_drv_probe(struct device *dev)
245{
246 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
247
248#ifdef CONFIG_KLOCWORK
249 if (!sdrv)
250 return -ENODEV;
251#endif
252
253 return sdrv->probe(to_spi_device(dev));
254}
255
256static int spi_drv_remove(struct device *dev)
257{
258 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
259
260#ifdef CONFIG_KLOCWORK
261 if (!sdrv)
262 return -ENODEV;
263#endif
264
265 return sdrv->remove(to_spi_device(dev));
266}
267
268static void spi_drv_shutdown(struct device *dev)
269{
270 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
271
272#ifdef CONFIG_KLOCWORK
273 if (!sdrv)
274 return;
275#endif
276
277 sdrv->shutdown(to_spi_device(dev));
278}
279
280/**
281 * spi_register_driver - register a SPI driver
282 * @sdrv: the driver to register
283 * Context: can sleep
284 */
285int spi_register_driver(struct spi_driver *sdrv)
286{
287 sdrv->driver.bus = &spi_bus_type;
288 if (sdrv->probe)
289 sdrv->driver.probe = spi_drv_probe;
290 if (sdrv->remove)
291 sdrv->driver.remove = spi_drv_remove;
292 if (sdrv->shutdown)
293 sdrv->driver.shutdown = spi_drv_shutdown;
294 return driver_register(&sdrv->driver);
295}
296EXPORT_SYMBOL_GPL(spi_register_driver);
297
298/*-------------------------------------------------------------------------*/
299
300/* SPI devices should normally not be created by SPI device drivers; that
301 * would make them board-specific. Similarly with SPI master drivers.
302 * Device registration normally goes into like arch/.../mach.../board-YYY.c
303 * with other readonly (flashable) information about mainboard devices.
304 */
305
306struct boardinfo {
307 struct list_head list;
308 struct spi_board_info board_info;
309};
310
311static LIST_HEAD(board_list);
312static LIST_HEAD(spi_master_list);
313
314/*
315 * Used to protect add/del opertion for board_info list and
316 * spi_master list, and their matching process
317 */
318static DEFINE_MUTEX(board_lock);
319
320/**
321 * spi_alloc_device - Allocate a new SPI device
322 * @master: Controller to which device is connected
323 * Context: can sleep
324 *
325 * Allows a driver to allocate and initialize a spi_device without
326 * registering it immediately. This allows a driver to directly
327 * fill the spi_device with device parameters before calling
328 * spi_add_device() on it.
329 *
330 * Caller is responsible to call spi_add_device() on the returned
331 * spi_device structure to add it to the SPI master. If the caller
332 * needs to discard the spi_device without adding it, then it should
333 * call spi_dev_put() on it.
334 *
335 * Returns a pointer to the new device, or NULL.
336 */
337struct spi_device *spi_alloc_device(struct spi_master *master)
338{
339 struct spi_device *spi;
340 struct device *dev = master->dev.parent;
341
342 if (!spi_master_get(master))
343 return NULL;
344
345 spi = kzalloc(sizeof *spi, GFP_KERNEL);
346 if (!spi) {
347 dev_err(dev, "cannot alloc spi_device\n");
348 spi_master_put(master);
349 return NULL;
350 }
351
352 spi->master = master;
353 spi->dev.parent = &master->dev;
354 spi->dev.bus = &spi_bus_type;
355 spi->dev.release = spidev_release;
356 device_initialize(&spi->dev);
357 return spi;
358}
359EXPORT_SYMBOL_GPL(spi_alloc_device);
360
361/**
362 * spi_add_device - Add spi_device allocated with spi_alloc_device
363 * @spi: spi_device to register
364 *
365 * Companion function to spi_alloc_device. Devices allocated with
366 * spi_alloc_device can be added onto the spi bus with this function.
367 *
368 * Returns 0 on success; negative errno on failure
369 */
370int spi_add_device(struct spi_device *spi)
371{
372 static DEFINE_MUTEX(spi_add_lock);
373 struct device *dev = spi->master->dev.parent;
374 struct device *d;
375 int status;
376
377 /* Chipselects are numbered 0..max; validate. */
378 if (spi->chip_select >= spi->master->num_chipselect) {
379 dev_err(dev, "cs%d >= max %d\n",
380 spi->chip_select,
381 spi->master->num_chipselect);
382 return -EINVAL;
383 }
384
385 /* Set the bus ID string */
386 dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
387 spi->chip_select);
388
389
390 /* We need to make sure there's no other device with this
391 * chipselect **BEFORE** we call setup(), else we'll trash
392 * its configuration. Lock against concurrent add() calls.
393 */
394 mutex_lock(&spi_add_lock);
395
396 d = bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));
397 if (d != NULL) {
398 dev_err(dev, "chipselect %d already in use\n",
399 spi->chip_select);
400 put_device(d);
401 status = -EBUSY;
402 goto done;
403 }
404
405 /* Drivers may modify this initial i/o setup, but will
406 * normally rely on the device being setup. Devices
407 * using SPI_CS_HIGH can't coexist well otherwise...
408 */
409 status = spi_setup(spi);
410 if (status < 0) {
411 dev_err(dev, "can't setup %s, status %d\n",
412 dev_name(&spi->dev), status);
413 goto done;
414 }
415
416 /* Device may be bound to an active driver when this returns */
417 status = device_add(&spi->dev);
418 if (status < 0)
419 dev_err(dev, "can't add %s, status %d\n",
420 dev_name(&spi->dev), status);
421 else
422 dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
423
424done:
425 mutex_unlock(&spi_add_lock);
426 return status;
427}
428EXPORT_SYMBOL_GPL(spi_add_device);
429
430/**
431 * spi_new_device - instantiate one new SPI device
432 * @master: Controller to which device is connected
433 * @chip: Describes the SPI device
434 * Context: can sleep
435 *
436 * On typical mainboards, this is purely internal; and it's not needed
437 * after board init creates the hard-wired devices. Some development
438 * platforms may not be able to use spi_register_board_info though, and
439 * this is exported so that for example a USB or parport based adapter
440 * driver could add devices (which it would learn about out-of-band).
441 *
442 * Returns the new device, or NULL.
443 */
444struct spi_device *spi_new_device(struct spi_master *master,
445 struct spi_board_info *chip)
446{
447 struct spi_device *proxy;
448 int status;
449
450 /* NOTE: caller did any chip->bus_num checks necessary.
451 *
452 * Also, unless we change the return value convention to use
453 * error-or-pointer (not NULL-or-pointer), troubleshootability
454 * suggests syslogged diagnostics are best here (ugh).
455 */
456
457 proxy = spi_alloc_device(master);
458 if (!proxy)
459 return NULL;
460
461 WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
462
463 proxy->chip_select = chip->chip_select;
464 proxy->max_speed_hz = chip->max_speed_hz;
465 proxy->mode = chip->mode;
466 proxy->irq = chip->irq;
467 strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
468 proxy->dev.platform_data = (void *) chip->platform_data;
469 proxy->controller_data = chip->controller_data;
470 proxy->controller_state = NULL;
471
472 status = spi_add_device(proxy);
473 if (status < 0) {
474 spi_dev_put(proxy);
475 return NULL;
476 }
477
478 return proxy;
479}
480EXPORT_SYMBOL_GPL(spi_new_device);
481
482static void spi_match_master_to_boardinfo(struct spi_master *master,
483 struct spi_board_info *bi)
484{
485 struct spi_device *dev;
486
487 if (master->bus_num != bi->bus_num)
488 return;
489
490 dev = spi_new_device(master, bi);
491 if (!dev)
492 dev_err(master->dev.parent, "can't create new device for %s\n",
493 bi->modalias);
494}
495
496/**
497 * spi_register_board_info - register SPI devices for a given board
498 * @info: array of chip descriptors
499 * @n: how many descriptors are provided
500 * Context: can sleep
501 *
502 * Board-specific early init code calls this (probably during arch_initcall)
503 * with segments of the SPI device table. Any device nodes are created later,
504 * after the relevant parent SPI controller (bus_num) is defined. We keep
505 * this table of devices forever, so that reloading a controller driver will
506 * not make Linux forget about these hard-wired devices.
507 *
508 * Other code can also call this, e.g. a particular add-on board might provide
509 * SPI devices through its expansion connector, so code initializing that board
510 * would naturally declare its SPI devices.
511 *
512 * The board info passed can safely be __initdata ... but be careful of
513 * any embedded pointers (platform_data, etc), they're copied as-is.
514 */
515int __devinit
516spi_register_board_info(struct spi_board_info const *info, unsigned n)
517{
518 struct boardinfo *bi;
519 int i;
520
521 if (!n)
522 return 0;
523
524 bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
525 if (!bi)
526 return -ENOMEM;
527
528 for (i = 0; i < n; i++, bi++, info++) {
529 struct spi_master *master;
530
531 memcpy(&bi->board_info, info, sizeof(*info));
532 mutex_lock(&board_lock);
533 list_add_tail(&bi->list, &board_list);
534 list_for_each_entry(master, &spi_master_list, list)
535 spi_match_master_to_boardinfo(master, &bi->board_info);
536 mutex_unlock(&board_lock);
537 }
538
539 return 0;
540}
541EXPORT_SYMBOL_GPL(spi_register_board_info);
542/*-------------------------------------------------------------------------*/
543
544/**
545 * spi_pump_messages - kthread work function which processes spi message queue
546 * @work: pointer to kthread work struct contained in the master struct
547 *
548 * This function checks if there is any spi message in the queue that
549 * needs processing and if so call out to the driver to initialize hardware
550 * and transfer each message.
551 *
552 */
553static void spi_pump_messages(struct kthread_work *work)
554{
555 struct spi_master *master =
556 container_of(work, struct spi_master, pump_messages);
557 unsigned long flags;
558 bool was_busy = false;
559 int ret;
560
561 /* Lock queue and check for queue work */
562 spin_lock_irqsave(&master->queue_lock, flags);
563 if (list_empty(&master->queue) || !master->running) {
564 if (master->busy) {
565 ret = master->unprepare_transfer_hardware(master);
566 if (ret) {
567 spin_unlock_irqrestore(&master->queue_lock, flags);
568 dev_err(&master->dev,
569 "failed to unprepare transfer hardware\n");
570 return;
571 }
572 }
573 master->busy = false;
574 spin_unlock_irqrestore(&master->queue_lock, flags);
575 return;
576 }
577
578 /* Make sure we are not already running a message */
579 if (master->cur_msg) {
580 spin_unlock_irqrestore(&master->queue_lock, flags);
581 return;
582 }
583 /* Extract head of queue */
584 master->cur_msg =
585 list_entry(master->queue.next, struct spi_message, queue);
586
587 list_del_init(&master->cur_msg->queue);
588 if (master->busy)
589 was_busy = true;
590 else
591 master->busy = true;
592 spin_unlock_irqrestore(&master->queue_lock, flags);
593
594 if (!was_busy) {
595 ret = master->prepare_transfer_hardware(master);
596 if (ret) {
597 dev_err(&master->dev,
598 "failed to prepare transfer hardware\n");
599 return;
600 }
601 }
602
603 ret = master->transfer_one_message(master, master->cur_msg);
604 if (ret) {
605 dev_err(&master->dev,
606 "failed to transfer one message from queue\n");
607 return;
608 }
609}
610
611static int spi_init_queue(struct spi_master *master)
612{
613 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
614
615 INIT_LIST_HEAD(&master->queue);
616 spin_lock_init(&master->queue_lock);
617
618 master->running = false;
619 master->busy = false;
620
621 init_kthread_worker(&master->kworker);
622 master->kworker_task = kthread_run(kthread_worker_fn,
623 &master->kworker,
624 dev_name(&master->dev));
625 if (IS_ERR(master->kworker_task)) {
626 dev_err(&master->dev, "failed to create message pump task\n");
627 return -ENOMEM;
628 }
629 init_kthread_work(&master->pump_messages, spi_pump_messages);
630
631 /*
632 * Master config will indicate if this controller should run the
633 * message pump with high (realtime) priority to reduce the transfer
634 * latency on the bus by minimising the delay between a transfer
635 * request and the scheduling of the message pump thread. Without this
636 * setting the message pump thread will remain at default priority.
637 */
638 if (master->rt) {
639 dev_info(&master->dev,
640 "will run message pump with realtime priority\n");
641 sched_setscheduler(master->kworker_task, SCHED_FIFO, &param);
642 }
643
644 return 0;
645}
646
647/**
648 * spi_get_next_queued_message() - called by driver to check for queued
649 * messages
650 * @master: the master to check for queued messages
651 *
652 * If there are more messages in the queue, the next message is returned from
653 * this call.
654 */
655struct spi_message *spi_get_next_queued_message(struct spi_master *master)
656{
657 struct spi_message *next;
658 unsigned long flags;
659
660 /* get a pointer to the next message, if any */
661 spin_lock_irqsave(&master->queue_lock, flags);
662 if (list_empty(&master->queue))
663 next = NULL;
664 else
665 next = list_entry(master->queue.next,
666 struct spi_message, queue);
667 spin_unlock_irqrestore(&master->queue_lock, flags);
668
669 return next;
670}
671EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
672
673/**
674 * spi_finalize_current_message() - the current message is complete
675 * @master: the master to return the message to
676 *
677 * Called by the driver to notify the core that the message in the front of the
678 * queue is complete and can be removed from the queue.
679 */
680void spi_finalize_current_message(struct spi_master *master)
681{
682 struct spi_message *mesg;
683 unsigned long flags;
684
685 spin_lock_irqsave(&master->queue_lock, flags);
686 mesg = master->cur_msg;
687 master->cur_msg = NULL;
688
689 queue_kthread_work(&master->kworker, &master->pump_messages);
690 spin_unlock_irqrestore(&master->queue_lock, flags);
691
692 mesg->state = NULL;
693 if (mesg->complete)
694 mesg->complete(mesg->context);
695}
696EXPORT_SYMBOL_GPL(spi_finalize_current_message);
697
698static int spi_start_queue(struct spi_master *master)
699{
700 unsigned long flags;
701
702 spin_lock_irqsave(&master->queue_lock, flags);
703
704 if (master->running || master->busy) {
705 spin_unlock_irqrestore(&master->queue_lock, flags);
706 return -EBUSY;
707 }
708
709 master->running = true;
710 master->cur_msg = NULL;
711 spin_unlock_irqrestore(&master->queue_lock, flags);
712
713 queue_kthread_work(&master->kworker, &master->pump_messages);
714
715 return 0;
716}
717
718static int spi_stop_queue(struct spi_master *master)
719{
720 unsigned long flags;
721 unsigned limit = 500;
722 int ret = 0;
723
724 spin_lock_irqsave(&master->queue_lock, flags);
725
726 /*
727 * This is a bit lame, but is optimized for the common execution path.
728 * A wait_queue on the master->busy could be used, but then the common
729 * execution path (pump_messages) would be required to call wake_up or
730 * friends on every SPI message. Do this instead.
731 */
732 while ((!list_empty(&master->queue) || master->busy) && limit--) {
733 spin_unlock_irqrestore(&master->queue_lock, flags);
734 msleep(10);
735 spin_lock_irqsave(&master->queue_lock, flags);
736 }
737
738 if (!list_empty(&master->queue) || master->busy)
739 ret = -EBUSY;
740 else
741 master->running = false;
742
743 spin_unlock_irqrestore(&master->queue_lock, flags);
744
745 if (ret) {
746 dev_warn(&master->dev,
747 "could not stop message queue\n");
748 return ret;
749 }
750 return ret;
751}
752
753static int spi_destroy_queue(struct spi_master *master)
754{
755 int ret;
756
757 ret = spi_stop_queue(master);
758
759 /*
760 * flush_kthread_worker will block until all work is done.
761 * If the reason that stop_queue timed out is that the work will never
762 * finish, then it does no good to call flush/stop thread, so
763 * return anyway.
764 */
765 if (ret) {
766 dev_err(&master->dev, "problem destroying queue\n");
767 return ret;
768 }
769
770 flush_kthread_worker(&master->kworker);
771 kthread_stop(master->kworker_task);
772
773 return 0;
774}
775
776/**
777 * spi_queued_transfer - transfer function for queued transfers
778 * @spi: spi device which is requesting transfer
779 * @msg: spi message which is to handled is queued to driver queue
780 */
781static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
782{
783 struct spi_master *master = spi->master;
784 unsigned long flags;
785
786 spin_lock_irqsave(&master->queue_lock, flags);
787
788 if (!master->running) {
789 spin_unlock_irqrestore(&master->queue_lock, flags);
790 return -ESHUTDOWN;
791 }
792 msg->actual_length = 0;
793 msg->status = -EINPROGRESS;
794
795 list_add_tail(&msg->queue, &master->queue);
796 if (master->running && !master->busy)
797 queue_kthread_work(&master->kworker, &master->pump_messages);
798
799 spin_unlock_irqrestore(&master->queue_lock, flags);
800 return 0;
801}
802
803static int spi_master_initialize_queue(struct spi_master *master)
804{
805 int ret;
806
807 master->queued = true;
808 master->transfer = spi_queued_transfer;
809
810 /* Initialize and start queue */
811 ret = spi_init_queue(master);
812 if (ret) {
813 dev_err(&master->dev, "problem initializing queue\n");
814 goto err_init_queue;
815 }
816 ret = spi_start_queue(master);
817 if (ret) {
818 dev_err(&master->dev, "problem starting queue\n");
819 goto err_start_queue;
820 }
821
822 return 0;
823
824err_start_queue:
825err_init_queue:
826 spi_destroy_queue(master);
827 return ret;
828}
829
830/*-------------------------------------------------------------------------*/
831
832static void spi_master_release(struct device *dev)
833{
834 struct spi_master *master;
835
836 master = container_of(dev, struct spi_master, dev);
837 kfree(master);
838}
839
840static struct class spi_master_class = {
841 .name = "spi_master",
842 .owner = THIS_MODULE,
843 .dev_release = spi_master_release,
844};
845
846
847
848/**
849 * spi_alloc_master - allocate SPI master controller
850 * @dev: the controller, possibly using the platform_bus
851 * @size: how much zeroed driver-private data to allocate; the pointer to this
852 * memory is in the driver_data field of the returned device,
853 * accessible with spi_master_get_devdata().
854 * Context: can sleep
855 *
856 * This call is used only by SPI master controller drivers, which are the
857 * only ones directly touching chip registers. It's how they allocate
858 * an spi_master structure, prior to calling spi_register_master().
859 *
860 * This must be called from context that can sleep. It returns the SPI
861 * master structure on success, else NULL.
862 *
863 * The caller is responsible for assigning the bus number and initializing
864 * the master's methods before calling spi_register_master(); and (after errors
865 * adding the device) calling spi_master_put() and kfree() to prevent a memory
866 * leak.
867 */
868struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
869{
870 struct spi_master *master;
871
872 if (!dev)
873 return NULL;
874
875 master = kzalloc(size + sizeof *master, GFP_KERNEL);
876 if (!master)
877 return NULL;
878
879 device_initialize(&master->dev);
880 master->dev.class = &spi_master_class;
881 master->dev.parent = get_device(dev);
882 spi_master_set_devdata(master, &master[1]);
883
884 return master;
885}
886EXPORT_SYMBOL_GPL(spi_alloc_master);
887
888/**
889 * spi_register_master - register SPI master controller
890 * @master: initialized master, originally from spi_alloc_master()
891 * Context: can sleep
892 *
893 * SPI master controllers connect to their drivers using some non-SPI bus,
894 * such as the platform bus. The final stage of probe() in that code
895 * includes calling spi_register_master() to hook up to this SPI bus glue.
896 *
897 * SPI controllers use board specific (often SOC specific) bus numbers,
898 * and board-specific addressing for SPI devices combines those numbers
899 * with chip select numbers. Since SPI does not directly support dynamic
900 * device identification, boards need configuration tables telling which
901 * chip is at which address.
902 *
903 * This must be called from context that can sleep. It returns zero on
904 * success, else a negative error code (dropping the master's refcount).
905 * After a successful return, the caller is responsible for calling
906 * spi_unregister_master().
907 */
908int spi_register_master(struct spi_master *master)
909{
910 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
911 struct device *dev = master->dev.parent;
912 struct boardinfo *bi;
913 int status = -ENODEV;
914 int dynamic = 0;
915
916 if (!dev)
917 return -ENODEV;
918
919 /* even if it's just one always-selected device, there must
920 * be at least one chipselect
921 */
922 if (master->num_chipselect == 0)
923 return -EINVAL;
924
925 /* convention: dynamically assigned bus IDs count down from the max */
926 if (master->bus_num < 0) {
927 /* FIXME switch to an IDR based scheme, something like
928 * I2C now uses, so we can't run out of "dynamic" IDs
929 */
930 master->bus_num = atomic_dec_return(&dyn_bus_id);
931 dynamic = 1;
932 }
933
934 spin_lock_init(&master->bus_lock_spinlock);
935 mutex_init(&master->bus_lock_mutex);
936 master->bus_lock_flag = 0;
937
938 /* register the device, then userspace will see it.
939 * registration fails if the bus ID is in use.
940 */
941 dev_set_name(&master->dev, "spi%u", master->bus_num);
942 status = device_add(&master->dev);
943 if (status < 0)
944 goto done;
945 dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
946 dynamic ? " (dynamic)" : "");
947
948 /* If we're using a queued driver, start the queue */
949 if (master->transfer)
950 dev_info(dev, "master is unqueued, this is deprecated\n");
951 else {
952 status = spi_master_initialize_queue(master);
953 if (status) {
954 device_unregister(&master->dev);
955 goto done;
956 }
957 }
958
959 mutex_lock(&board_lock);
960 list_add_tail(&master->list, &spi_master_list);
961 list_for_each_entry(bi, &board_list, list)
962 spi_match_master_to_boardinfo(master, &bi->board_info);
963 mutex_unlock(&board_lock);
964
965 /* Register devices from the device tree */
966 of_register_spi_devices(master);
967done:
968 return status;
969}
970EXPORT_SYMBOL_GPL(spi_register_master);
971
972static int __unregister(struct device *dev, void *null)
973{
974 spi_unregister_device(to_spi_device(dev));
975 return 0;
976}
977
978/**
979 * spi_unregister_master - unregister SPI master controller
980 * @master: the master being unregistered
981 * Context: can sleep
982 *
983 * This call is used only by SPI master controller drivers, which are the
984 * only ones directly touching chip registers.
985 *
986 * This must be called from context that can sleep.
987 */
988void spi_unregister_master(struct spi_master *master)
989{
990 int dummy;
991
992 if (master->queued) {
993 if (spi_destroy_queue(master))
994 dev_err(&master->dev, "queue remove failed\n");
995 }
996
997 mutex_lock(&board_lock);
998 list_del(&master->list);
999 mutex_unlock(&board_lock);
1000
1001 dummy = device_for_each_child(&master->dev, NULL, __unregister);
1002 device_unregister(&master->dev);
1003}
1004EXPORT_SYMBOL_GPL(spi_unregister_master);
1005
1006int spi_master_suspend(struct spi_master *master)
1007{
1008 int ret;
1009
1010 /* Basically no-ops for non-queued masters */
1011 if (!master->queued)
1012 return 0;
1013
1014 ret = spi_stop_queue(master);
1015 if (ret)
1016 dev_err(&master->dev, "queue stop failed\n");
1017
1018 return ret;
1019}
1020EXPORT_SYMBOL_GPL(spi_master_suspend);
1021
1022int spi_master_resume(struct spi_master *master)
1023{
1024 int ret;
1025
1026 if (!master->queued)
1027 return 0;
1028
1029 ret = spi_start_queue(master);
1030 if (ret)
1031 dev_err(&master->dev, "queue restart failed\n");
1032
1033 return ret;
1034}
1035EXPORT_SYMBOL_GPL(spi_master_resume);
1036
1037static int __spi_master_match(struct device *dev, void *data)
1038{
1039 struct spi_master *m;
1040 u16 *bus_num = data;
1041
1042 m = container_of(dev, struct spi_master, dev);
1043 return m->bus_num == *bus_num;
1044}
1045
1046/**
1047 * spi_busnum_to_master - look up master associated with bus_num
1048 * @bus_num: the master's bus number
1049 * Context: can sleep
1050 *
1051 * This call may be used with devices that are registered after
1052 * arch init time. It returns a refcounted pointer to the relevant
1053 * spi_master (which the caller must release), or NULL if there is
1054 * no such master registered.
1055 */
1056struct spi_master *spi_busnum_to_master(u16 bus_num)
1057{
1058 struct device *dev;
1059 struct spi_master *master = NULL;
1060
1061 dev = class_find_device(&spi_master_class, NULL, &bus_num,
1062 __spi_master_match);
1063 if (dev)
1064 master = container_of(dev, struct spi_master, dev);
1065 /* reference got in class_find_device */
1066 return master;
1067}
1068EXPORT_SYMBOL_GPL(spi_busnum_to_master);
1069
1070
1071/*-------------------------------------------------------------------------*/
1072
1073/* Core methods for SPI master protocol drivers. Some of the
1074 * other core methods are currently defined as inline functions.
1075 */
1076
1077/**
1078 * spi_setup - setup SPI mode and clock rate
1079 * @spi: the device whose settings are being modified
1080 * Context: can sleep, and no requests are queued to the device
1081 *
1082 * SPI protocol drivers may need to update the transfer mode if the
1083 * device doesn't work with its default. They may likewise need
1084 * to update clock rates or word sizes from initial values. This function
1085 * changes those settings, and must be called from a context that can sleep.
1086 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
1087 * effect the next time the device is selected and data is transferred to
1088 * or from it. When this function returns, the spi device is deselected.
1089 *
1090 * Note that this call will fail if the protocol driver specifies an option
1091 * that the underlying controller or its driver does not support. For
1092 * example, not all hardware supports wire transfers using nine bit words,
1093 * LSB-first wire encoding, or active-high chipselects.
1094 */
1095int spi_setup(struct spi_device *spi)
1096{
1097 unsigned bad_bits;
1098 int status;
1099
1100 /* help drivers fail *cleanly* when they need options
1101 * that aren't supported with their current master
1102 */
1103 bad_bits = spi->mode & ~spi->master->mode_bits;
1104 if (bad_bits) {
1105 dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
1106 bad_bits);
1107 return -EINVAL;
1108 }
1109
1110 if (!spi->bits_per_word)
1111 spi->bits_per_word = 8;
1112
1113 status = spi->master->setup(spi);
1114
1115 dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
1116 "%u bits/w, %u Hz max --> %d\n",
1117 (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
1118 (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
1119 (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
1120 (spi->mode & SPI_3WIRE) ? "3wire, " : "",
1121 (spi->mode & SPI_LOOP) ? "loopback, " : "",
1122 spi->bits_per_word, spi->max_speed_hz,
1123 status);
1124
1125 return status;
1126}
1127EXPORT_SYMBOL_GPL(spi_setup);
1128
1129static int __spi_async(struct spi_device *spi, struct spi_message *message)
1130{
1131 struct spi_master *master = spi->master;
1132
1133 /* Half-duplex links include original MicroWire, and ones with
1134 * only one data pin like SPI_3WIRE (switches direction) or where
1135 * either MOSI or MISO is missing. They can also be caused by
1136 * software limitations.
1137 */
1138 if ((master->flags & SPI_MASTER_HALF_DUPLEX)
1139 || (spi->mode & SPI_3WIRE)) {
1140 struct spi_transfer *xfer;
1141 unsigned flags = master->flags;
1142
1143 list_for_each_entry(xfer, &message->transfers, transfer_list) {
1144 if (xfer->rx_buf && xfer->tx_buf)
1145 return -EINVAL;
1146 if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
1147 return -EINVAL;
1148 if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
1149 return -EINVAL;
1150 }
1151 }
1152
1153 message->spi = spi;
1154 message->status = -EINPROGRESS;
1155 return master->transfer(spi, message);
1156}
1157
1158/**
1159 * spi_async - asynchronous SPI transfer
1160 * @spi: device with which data will be exchanged
1161 * @message: describes the data transfers, including completion callback
1162 * Context: any (irqs may be blocked, etc)
1163 *
1164 * This call may be used in_irq and other contexts which can't sleep,
1165 * as well as from task contexts which can sleep.
1166 *
1167 * The completion callback is invoked in a context which can't sleep.
1168 * Before that invocation, the value of message->status is undefined.
1169 * When the callback is issued, message->status holds either zero (to
1170 * indicate complete success) or a negative error code. After that
1171 * callback returns, the driver which issued the transfer request may
1172 * deallocate the associated memory; it's no longer in use by any SPI
1173 * core or controller driver code.
1174 *
1175 * Note that although all messages to a spi_device are handled in
1176 * FIFO order, messages may go to different devices in other orders.
1177 * Some device might be higher priority, or have various "hard" access
1178 * time requirements, for example.
1179 *
1180 * On detection of any fault during the transfer, processing of
1181 * the entire message is aborted, and the device is deselected.
1182 * Until returning from the associated message completion callback,
1183 * no other spi_message queued to that device will be processed.
1184 * (This rule applies equally to all the synchronous transfer calls,
1185 * which are wrappers around this core asynchronous primitive.)
1186 */
1187int spi_async(struct spi_device *spi, struct spi_message *message)
1188{
1189 struct spi_master *master = spi->master;
1190 int ret;
1191 unsigned long flags;
1192
1193 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1194
1195 if (master->bus_lock_flag)
1196 ret = -EBUSY;
1197 else
1198 ret = __spi_async(spi, message);
1199
1200 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1201
1202 return ret;
1203}
1204EXPORT_SYMBOL_GPL(spi_async);
1205
1206/**
1207 * spi_async_locked - version of spi_async with exclusive bus usage
1208 * @spi: device with which data will be exchanged
1209 * @message: describes the data transfers, including completion callback
1210 * Context: any (irqs may be blocked, etc)
1211 *
1212 * This call may be used in_irq and other contexts which can't sleep,
1213 * as well as from task contexts which can sleep.
1214 *
1215 * The completion callback is invoked in a context which can't sleep.
1216 * Before that invocation, the value of message->status is undefined.
1217 * When the callback is issued, message->status holds either zero (to
1218 * indicate complete success) or a negative error code. After that
1219 * callback returns, the driver which issued the transfer request may
1220 * deallocate the associated memory; it's no longer in use by any SPI
1221 * core or controller driver code.
1222 *
1223 * Note that although all messages to a spi_device are handled in
1224 * FIFO order, messages may go to different devices in other orders.
1225 * Some device might be higher priority, or have various "hard" access
1226 * time requirements, for example.
1227 *
1228 * On detection of any fault during the transfer, processing of
1229 * the entire message is aborted, and the device is deselected.
1230 * Until returning from the associated message completion callback,
1231 * no other spi_message queued to that device will be processed.
1232 * (This rule applies equally to all the synchronous transfer calls,
1233 * which are wrappers around this core asynchronous primitive.)
1234 */
1235int spi_async_locked(struct spi_device *spi, struct spi_message *message)
1236{
1237 struct spi_master *master = spi->master;
1238 int ret;
1239 unsigned long flags;
1240
1241 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1242
1243 ret = __spi_async(spi, message);
1244
1245 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1246
1247 return ret;
1248
1249}
1250EXPORT_SYMBOL_GPL(spi_async_locked);
1251
1252
1253/*-------------------------------------------------------------------------*/
1254
1255/* Utility methods for SPI master protocol drivers, layered on
1256 * top of the core. Some other utility methods are defined as
1257 * inline functions.
1258 */
1259
1260static void spi_complete(void *arg)
1261{
1262 complete(arg);
1263}
1264
1265static int __spi_sync(struct spi_device *spi, struct spi_message *message,
1266 int bus_locked)
1267{
1268 DECLARE_COMPLETION_ONSTACK(done);
1269 int status;
1270 struct spi_master *master = spi->master;
1271
1272 message->complete = spi_complete;
1273 message->context = &done;
1274
1275 if (!bus_locked)
1276 mutex_lock(&master->bus_lock_mutex);
1277
1278 status = spi_async_locked(spi, message);
1279
1280 if (!bus_locked)
1281 mutex_unlock(&master->bus_lock_mutex);
1282
1283 if (status == 0) {
1284 wait_for_completion(&done);
1285 status = message->status;
1286 }
1287 message->context = NULL;
1288 return status;
1289}
1290
1291/**
1292 * spi_sync - blocking/synchronous SPI data transfers
1293 * @spi: device with which data will be exchanged
1294 * @message: describes the data transfers
1295 * Context: can sleep
1296 *
1297 * This call may only be used from a context that may sleep. The sleep
1298 * is non-interruptible, and has no timeout. Low-overhead controller
1299 * drivers may DMA directly into and out of the message buffers.
1300 *
1301 * Note that the SPI device's chip select is active during the message,
1302 * and then is normally disabled between messages. Drivers for some
1303 * frequently-used devices may want to minimize costs of selecting a chip,
1304 * by leaving it selected in anticipation that the next message will go
1305 * to the same chip. (That may increase power usage.)
1306 *
1307 * Also, the caller is guaranteeing that the memory associated with the
1308 * message will not be freed before this call returns.
1309 *
1310 * It returns zero on success, else a negative error code.
1311 */
1312int spi_sync(struct spi_device *spi, struct spi_message *message)
1313{
1314 return __spi_sync(spi, message, 0);
1315}
1316EXPORT_SYMBOL_GPL(spi_sync);
1317
1318/**
1319 * spi_sync_locked - version of spi_sync with exclusive bus usage
1320 * @spi: device with which data will be exchanged
1321 * @message: describes the data transfers
1322 * Context: can sleep
1323 *
1324 * This call may only be used from a context that may sleep. The sleep
1325 * is non-interruptible, and has no timeout. Low-overhead controller
1326 * drivers may DMA directly into and out of the message buffers.
1327 *
1328 * This call should be used by drivers that require exclusive access to the
1329 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
1330 * be released by a spi_bus_unlock call when the exclusive access is over.
1331 *
1332 * It returns zero on success, else a negative error code.
1333 */
1334int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
1335{
1336 return __spi_sync(spi, message, 1);
1337}
1338EXPORT_SYMBOL_GPL(spi_sync_locked);
1339
1340/**
1341 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
1342 * @master: SPI bus master that should be locked for exclusive bus access
1343 * Context: can sleep
1344 *
1345 * This call may only be used from a context that may sleep. The sleep
1346 * is non-interruptible, and has no timeout.
1347 *
1348 * This call should be used by drivers that require exclusive access to the
1349 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
1350 * exclusive access is over. Data transfer must be done by spi_sync_locked
1351 * and spi_async_locked calls when the SPI bus lock is held.
1352 *
1353 * It returns zero on success, else a negative error code.
1354 */
1355int spi_bus_lock(struct spi_master *master)
1356{
1357 unsigned long flags;
1358
1359 mutex_lock(&master->bus_lock_mutex);
1360
1361 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1362 master->bus_lock_flag = 1;
1363 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1364
1365 /* mutex remains locked until spi_bus_unlock is called */
1366
1367 return 0;
1368}
1369EXPORT_SYMBOL_GPL(spi_bus_lock);
1370
1371/**
1372 * spi_bus_unlock - release the lock for exclusive SPI bus usage
1373 * @master: SPI bus master that was locked for exclusive bus access
1374 * Context: can sleep
1375 *
1376 * This call may only be used from a context that may sleep. The sleep
1377 * is non-interruptible, and has no timeout.
1378 *
1379 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
1380 * call.
1381 *
1382 * It returns zero on success, else a negative error code.
1383 */
1384int spi_bus_unlock(struct spi_master *master)
1385{
1386 master->bus_lock_flag = 0;
1387
1388 mutex_unlock(&master->bus_lock_mutex);
1389
1390 return 0;
1391}
1392EXPORT_SYMBOL_GPL(spi_bus_unlock);
1393
1394/* portable code must never pass more than 32 bytes */
1395#define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
1396
1397static u8 *buf;
1398
1399/**
1400 * spi_write_then_read - SPI synchronous write followed by read
1401 * @spi: device with which data will be exchanged
1402 * @txbuf: data to be written (need not be dma-safe)
1403 * @n_tx: size of txbuf, in bytes
1404 * @rxbuf: buffer into which data will be read (need not be dma-safe)
1405 * @n_rx: size of rxbuf, in bytes
1406 * Context: can sleep
1407 *
1408 * This performs a half duplex MicroWire style transaction with the
1409 * device, sending txbuf and then reading rxbuf. The return value
1410 * is zero for success, else a negative errno status code.
1411 * This call may only be used from a context that may sleep.
1412 *
1413 * Parameters to this routine are always copied using a small buffer;
1414 * portable code should never use this for more than 32 bytes.
1415 * Performance-sensitive or bulk transfer code should instead use
1416 * spi_{async,sync}() calls with dma-safe buffers.
1417 */
1418int spi_write_then_read(struct spi_device *spi,
1419 const void *txbuf, unsigned n_tx,
1420 void *rxbuf, unsigned n_rx)
1421{
1422 static DEFINE_MUTEX(lock);
1423
1424 int status;
1425 struct spi_message message;
1426 struct spi_transfer x[2];
1427 u8 *local_buf;
1428
1429 /* Use preallocated DMA-safe buffer. We can't avoid copying here,
1430 * (as a pure convenience thing), but we can keep heap costs
1431 * out of the hot path ...
1432 */
1433 if ((n_tx + n_rx) > SPI_BUFSIZ) {
1434 dev_err(&spi->dev, "total len %d > SPI_BUFSIZ %d.", (n_tx + n_rx), SPI_BUFSIZ);
1435 return -EINVAL;
1436 }
1437
1438 spi_message_init(&message);
1439 memset(x, 0, sizeof x);
1440 if (n_tx) {
1441 x[0].len = n_tx;
1442 spi_message_add_tail(&x[0], &message);
1443 }
1444 if (n_rx) {
1445 x[1].len = n_rx;
1446 spi_message_add_tail(&x[1], &message);
1447 }
1448
1449 /* ... unless someone else is using the pre-allocated buffer */
1450 if (!mutex_trylock(&lock)) {
1451 local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1452 if (!local_buf)
1453 return -ENOMEM;
1454 } else
1455 local_buf = buf;
1456
1457 memcpy(local_buf, txbuf, n_tx);
1458 x[0].tx_buf = local_buf;
1459 x[1].rx_buf = local_buf + n_tx;
1460
1461 /* do the i/o */
1462 status = spi_sync(spi, &message);
1463 if (status == 0)
1464 memcpy(rxbuf, x[1].rx_buf, n_rx);
1465
1466 if (x[0].tx_buf == buf)
1467 mutex_unlock(&lock);
1468 else
1469 kfree(local_buf);
1470
1471 return status;
1472}
1473EXPORT_SYMBOL_GPL(spi_write_then_read);
1474
1475/*-------------------------------------------------------------------------*/
1476
1477static int __init spi_init(void)
1478{
1479 int status;
1480
1481 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1482 if (!buf) {
1483 status = -ENOMEM;
1484 goto err0;
1485 }
1486
1487 status = bus_register(&spi_bus_type);
1488 if (status < 0)
1489 goto err1;
1490
1491 status = class_register(&spi_master_class);
1492 if (status < 0)
1493 goto err2;
1494 return 0;
1495
1496err2:
1497 bus_unregister(&spi_bus_type);
1498err1:
1499 kfree(buf);
1500 buf = NULL;
1501err0:
1502 return status;
1503}
1504
1505/* board_info is normally registered in arch_initcall(),
1506 * but even essential drivers wait till later
1507 *
1508 * REVISIT only boardinfo really needs static linking. the rest (device and
1509 * driver registration) _could_ be dynamically linked (modular) ... costs
1510 * include needing to have boardinfo data structures be much more public.
1511 */
1512postcore_initcall(spi_init);
1513