Loading...
1/*
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
33static void spidev_release(struct device *dev)
34{
35 struct spi_device *spi = to_spi_device(dev);
36
37 /* spi masters may cleanup for released devices */
38 if (spi->master->cleanup)
39 spi->master->cleanup(spi);
40
41 spi_master_put(spi->master);
42 kfree(spi);
43}
44
45static ssize_t
46modalias_show(struct device *dev, struct device_attribute *a, char *buf)
47{
48 const struct spi_device *spi = to_spi_device(dev);
49
50 return sprintf(buf, "%s\n", spi->modalias);
51}
52
53static struct device_attribute spi_dev_attrs[] = {
54 __ATTR_RO(modalias),
55 __ATTR_NULL,
56};
57
58/* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
59 * and the sysfs version makes coldplug work too.
60 */
61
62static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
63 const struct spi_device *sdev)
64{
65 while (id->name[0]) {
66 if (!strcmp(sdev->modalias, id->name))
67 return id;
68 id++;
69 }
70 return NULL;
71}
72
73const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
74{
75 const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
76
77 return spi_match_id(sdrv->id_table, sdev);
78}
79EXPORT_SYMBOL_GPL(spi_get_device_id);
80
81static int spi_match_device(struct device *dev, struct device_driver *drv)
82{
83 const struct spi_device *spi = to_spi_device(dev);
84 const struct spi_driver *sdrv = to_spi_driver(drv);
85
86 /* Attempt an OF style match */
87 if (of_driver_match_device(dev, drv))
88 return 1;
89
90 if (sdrv->id_table)
91 return !!spi_match_id(sdrv->id_table, spi);
92
93 return strcmp(spi->modalias, drv->name) == 0;
94}
95
96static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
97{
98 const struct spi_device *spi = to_spi_device(dev);
99
100 add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
101 return 0;
102}
103
104#ifdef CONFIG_PM_SLEEP
105static int spi_legacy_suspend(struct device *dev, pm_message_t message)
106{
107 int value = 0;
108 struct spi_driver *drv = to_spi_driver(dev->driver);
109
110 /* suspend will stop irqs and dma; no more i/o */
111 if (drv) {
112 if (drv->suspend)
113 value = drv->suspend(to_spi_device(dev), message);
114 else
115 dev_dbg(dev, "... can't suspend\n");
116 }
117 return value;
118}
119
120static int spi_legacy_resume(struct device *dev)
121{
122 int value = 0;
123 struct spi_driver *drv = to_spi_driver(dev->driver);
124
125 /* resume may restart the i/o queue */
126 if (drv) {
127 if (drv->resume)
128 value = drv->resume(to_spi_device(dev));
129 else
130 dev_dbg(dev, "... can't resume\n");
131 }
132 return value;
133}
134
135static int spi_pm_suspend(struct device *dev)
136{
137 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
138
139 if (pm)
140 return pm_generic_suspend(dev);
141 else
142 return spi_legacy_suspend(dev, PMSG_SUSPEND);
143}
144
145static int spi_pm_resume(struct device *dev)
146{
147 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
148
149 if (pm)
150 return pm_generic_resume(dev);
151 else
152 return spi_legacy_resume(dev);
153}
154
155static int spi_pm_freeze(struct device *dev)
156{
157 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
158
159 if (pm)
160 return pm_generic_freeze(dev);
161 else
162 return spi_legacy_suspend(dev, PMSG_FREEZE);
163}
164
165static int spi_pm_thaw(struct device *dev)
166{
167 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
168
169 if (pm)
170 return pm_generic_thaw(dev);
171 else
172 return spi_legacy_resume(dev);
173}
174
175static int spi_pm_poweroff(struct device *dev)
176{
177 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
178
179 if (pm)
180 return pm_generic_poweroff(dev);
181 else
182 return spi_legacy_suspend(dev, PMSG_HIBERNATE);
183}
184
185static int spi_pm_restore(struct device *dev)
186{
187 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
188
189 if (pm)
190 return pm_generic_restore(dev);
191 else
192 return spi_legacy_resume(dev);
193}
194#else
195#define spi_pm_suspend NULL
196#define spi_pm_resume NULL
197#define spi_pm_freeze NULL
198#define spi_pm_thaw NULL
199#define spi_pm_poweroff NULL
200#define spi_pm_restore NULL
201#endif
202
203static const struct dev_pm_ops spi_pm = {
204 .suspend = spi_pm_suspend,
205 .resume = spi_pm_resume,
206 .freeze = spi_pm_freeze,
207 .thaw = spi_pm_thaw,
208 .poweroff = spi_pm_poweroff,
209 .restore = spi_pm_restore,
210 SET_RUNTIME_PM_OPS(
211 pm_generic_runtime_suspend,
212 pm_generic_runtime_resume,
213 pm_generic_runtime_idle
214 )
215};
216
217struct bus_type spi_bus_type = {
218 .name = "spi",
219 .dev_attrs = spi_dev_attrs,
220 .match = spi_match_device,
221 .uevent = spi_uevent,
222 .pm = &spi_pm,
223};
224EXPORT_SYMBOL_GPL(spi_bus_type);
225
226
227static int spi_drv_probe(struct device *dev)
228{
229 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
230
231 return sdrv->probe(to_spi_device(dev));
232}
233
234static int spi_drv_remove(struct device *dev)
235{
236 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
237
238 return sdrv->remove(to_spi_device(dev));
239}
240
241static void spi_drv_shutdown(struct device *dev)
242{
243 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
244
245 sdrv->shutdown(to_spi_device(dev));
246}
247
248/**
249 * spi_register_driver - register a SPI driver
250 * @sdrv: the driver to register
251 * Context: can sleep
252 */
253int spi_register_driver(struct spi_driver *sdrv)
254{
255 sdrv->driver.bus = &spi_bus_type;
256 if (sdrv->probe)
257 sdrv->driver.probe = spi_drv_probe;
258 if (sdrv->remove)
259 sdrv->driver.remove = spi_drv_remove;
260 if (sdrv->shutdown)
261 sdrv->driver.shutdown = spi_drv_shutdown;
262 return driver_register(&sdrv->driver);
263}
264EXPORT_SYMBOL_GPL(spi_register_driver);
265
266/*-------------------------------------------------------------------------*/
267
268/* SPI devices should normally not be created by SPI device drivers; that
269 * would make them board-specific. Similarly with SPI master drivers.
270 * Device registration normally goes into like arch/.../mach.../board-YYY.c
271 * with other readonly (flashable) information about mainboard devices.
272 */
273
274struct boardinfo {
275 struct list_head list;
276 struct spi_board_info board_info;
277};
278
279static LIST_HEAD(board_list);
280static LIST_HEAD(spi_master_list);
281
282/*
283 * Used to protect add/del opertion for board_info list and
284 * spi_master list, and their matching process
285 */
286static DEFINE_MUTEX(board_lock);
287
288/**
289 * spi_alloc_device - Allocate a new SPI device
290 * @master: Controller to which device is connected
291 * Context: can sleep
292 *
293 * Allows a driver to allocate and initialize a spi_device without
294 * registering it immediately. This allows a driver to directly
295 * fill the spi_device with device parameters before calling
296 * spi_add_device() on it.
297 *
298 * Caller is responsible to call spi_add_device() on the returned
299 * spi_device structure to add it to the SPI master. If the caller
300 * needs to discard the spi_device without adding it, then it should
301 * call spi_dev_put() on it.
302 *
303 * Returns a pointer to the new device, or NULL.
304 */
305struct spi_device *spi_alloc_device(struct spi_master *master)
306{
307 struct spi_device *spi;
308 struct device *dev = master->dev.parent;
309
310 if (!spi_master_get(master))
311 return NULL;
312
313 spi = kzalloc(sizeof *spi, GFP_KERNEL);
314 if (!spi) {
315 dev_err(dev, "cannot alloc spi_device\n");
316 spi_master_put(master);
317 return NULL;
318 }
319
320 spi->master = master;
321 spi->dev.parent = dev;
322 spi->dev.bus = &spi_bus_type;
323 spi->dev.release = spidev_release;
324 device_initialize(&spi->dev);
325 return spi;
326}
327EXPORT_SYMBOL_GPL(spi_alloc_device);
328
329/**
330 * spi_add_device - Add spi_device allocated with spi_alloc_device
331 * @spi: spi_device to register
332 *
333 * Companion function to spi_alloc_device. Devices allocated with
334 * spi_alloc_device can be added onto the spi bus with this function.
335 *
336 * Returns 0 on success; negative errno on failure
337 */
338int spi_add_device(struct spi_device *spi)
339{
340 static DEFINE_MUTEX(spi_add_lock);
341 struct device *dev = spi->master->dev.parent;
342 struct device *d;
343 int status;
344
345 /* Chipselects are numbered 0..max; validate. */
346 if (spi->chip_select >= spi->master->num_chipselect) {
347 dev_err(dev, "cs%d >= max %d\n",
348 spi->chip_select,
349 spi->master->num_chipselect);
350 return -EINVAL;
351 }
352
353 /* Set the bus ID string */
354 dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
355 spi->chip_select);
356
357
358 /* We need to make sure there's no other device with this
359 * chipselect **BEFORE** we call setup(), else we'll trash
360 * its configuration. Lock against concurrent add() calls.
361 */
362 mutex_lock(&spi_add_lock);
363
364 d = bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));
365 if (d != NULL) {
366 dev_err(dev, "chipselect %d already in use\n",
367 spi->chip_select);
368 put_device(d);
369 status = -EBUSY;
370 goto done;
371 }
372
373 /* Drivers may modify this initial i/o setup, but will
374 * normally rely on the device being setup. Devices
375 * using SPI_CS_HIGH can't coexist well otherwise...
376 */
377 status = spi_setup(spi);
378 if (status < 0) {
379 dev_err(dev, "can't setup %s, status %d\n",
380 dev_name(&spi->dev), status);
381 goto done;
382 }
383
384 /* Device may be bound to an active driver when this returns */
385 status = device_add(&spi->dev);
386 if (status < 0)
387 dev_err(dev, "can't add %s, status %d\n",
388 dev_name(&spi->dev), status);
389 else
390 dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
391
392done:
393 mutex_unlock(&spi_add_lock);
394 return status;
395}
396EXPORT_SYMBOL_GPL(spi_add_device);
397
398/**
399 * spi_new_device - instantiate one new SPI device
400 * @master: Controller to which device is connected
401 * @chip: Describes the SPI device
402 * Context: can sleep
403 *
404 * On typical mainboards, this is purely internal; and it's not needed
405 * after board init creates the hard-wired devices. Some development
406 * platforms may not be able to use spi_register_board_info though, and
407 * this is exported so that for example a USB or parport based adapter
408 * driver could add devices (which it would learn about out-of-band).
409 *
410 * Returns the new device, or NULL.
411 */
412struct spi_device *spi_new_device(struct spi_master *master,
413 struct spi_board_info *chip)
414{
415 struct spi_device *proxy;
416 int status;
417
418 /* NOTE: caller did any chip->bus_num checks necessary.
419 *
420 * Also, unless we change the return value convention to use
421 * error-or-pointer (not NULL-or-pointer), troubleshootability
422 * suggests syslogged diagnostics are best here (ugh).
423 */
424
425 proxy = spi_alloc_device(master);
426 if (!proxy)
427 return NULL;
428
429 WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
430
431 proxy->chip_select = chip->chip_select;
432 proxy->max_speed_hz = chip->max_speed_hz;
433 proxy->mode = chip->mode;
434 proxy->irq = chip->irq;
435 strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
436 proxy->dev.platform_data = (void *) chip->platform_data;
437 proxy->controller_data = chip->controller_data;
438 proxy->controller_state = NULL;
439
440 status = spi_add_device(proxy);
441 if (status < 0) {
442 spi_dev_put(proxy);
443 return NULL;
444 }
445
446 return proxy;
447}
448EXPORT_SYMBOL_GPL(spi_new_device);
449
450static void spi_match_master_to_boardinfo(struct spi_master *master,
451 struct spi_board_info *bi)
452{
453 struct spi_device *dev;
454
455 if (master->bus_num != bi->bus_num)
456 return;
457
458 dev = spi_new_device(master, bi);
459 if (!dev)
460 dev_err(master->dev.parent, "can't create new device for %s\n",
461 bi->modalias);
462}
463
464/**
465 * spi_register_board_info - register SPI devices for a given board
466 * @info: array of chip descriptors
467 * @n: how many descriptors are provided
468 * Context: can sleep
469 *
470 * Board-specific early init code calls this (probably during arch_initcall)
471 * with segments of the SPI device table. Any device nodes are created later,
472 * after the relevant parent SPI controller (bus_num) is defined. We keep
473 * this table of devices forever, so that reloading a controller driver will
474 * not make Linux forget about these hard-wired devices.
475 *
476 * Other code can also call this, e.g. a particular add-on board might provide
477 * SPI devices through its expansion connector, so code initializing that board
478 * would naturally declare its SPI devices.
479 *
480 * The board info passed can safely be __initdata ... but be careful of
481 * any embedded pointers (platform_data, etc), they're copied as-is.
482 */
483int __init
484spi_register_board_info(struct spi_board_info const *info, unsigned n)
485{
486 struct boardinfo *bi;
487 int i;
488
489 bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
490 if (!bi)
491 return -ENOMEM;
492
493 for (i = 0; i < n; i++, bi++, info++) {
494 struct spi_master *master;
495
496 memcpy(&bi->board_info, info, sizeof(*info));
497 mutex_lock(&board_lock);
498 list_add_tail(&bi->list, &board_list);
499 list_for_each_entry(master, &spi_master_list, list)
500 spi_match_master_to_boardinfo(master, &bi->board_info);
501 mutex_unlock(&board_lock);
502 }
503
504 return 0;
505}
506
507/*-------------------------------------------------------------------------*/
508
509static void spi_master_release(struct device *dev)
510{
511 struct spi_master *master;
512
513 master = container_of(dev, struct spi_master, dev);
514 kfree(master);
515}
516
517static struct class spi_master_class = {
518 .name = "spi_master",
519 .owner = THIS_MODULE,
520 .dev_release = spi_master_release,
521};
522
523
524/**
525 * spi_alloc_master - allocate SPI master controller
526 * @dev: the controller, possibly using the platform_bus
527 * @size: how much zeroed driver-private data to allocate; the pointer to this
528 * memory is in the driver_data field of the returned device,
529 * accessible with spi_master_get_devdata().
530 * Context: can sleep
531 *
532 * This call is used only by SPI master controller drivers, which are the
533 * only ones directly touching chip registers. It's how they allocate
534 * an spi_master structure, prior to calling spi_register_master().
535 *
536 * This must be called from context that can sleep. It returns the SPI
537 * master structure on success, else NULL.
538 *
539 * The caller is responsible for assigning the bus number and initializing
540 * the master's methods before calling spi_register_master(); and (after errors
541 * adding the device) calling spi_master_put() to prevent a memory leak.
542 */
543struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
544{
545 struct spi_master *master;
546
547 if (!dev)
548 return NULL;
549
550 master = kzalloc(size + sizeof *master, GFP_KERNEL);
551 if (!master)
552 return NULL;
553
554 device_initialize(&master->dev);
555 master->dev.class = &spi_master_class;
556 master->dev.parent = get_device(dev);
557 spi_master_set_devdata(master, &master[1]);
558
559 return master;
560}
561EXPORT_SYMBOL_GPL(spi_alloc_master);
562
563/**
564 * spi_register_master - register SPI master controller
565 * @master: initialized master, originally from spi_alloc_master()
566 * Context: can sleep
567 *
568 * SPI master controllers connect to their drivers using some non-SPI bus,
569 * such as the platform bus. The final stage of probe() in that code
570 * includes calling spi_register_master() to hook up to this SPI bus glue.
571 *
572 * SPI controllers use board specific (often SOC specific) bus numbers,
573 * and board-specific addressing for SPI devices combines those numbers
574 * with chip select numbers. Since SPI does not directly support dynamic
575 * device identification, boards need configuration tables telling which
576 * chip is at which address.
577 *
578 * This must be called from context that can sleep. It returns zero on
579 * success, else a negative error code (dropping the master's refcount).
580 * After a successful return, the caller is responsible for calling
581 * spi_unregister_master().
582 */
583int spi_register_master(struct spi_master *master)
584{
585 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
586 struct device *dev = master->dev.parent;
587 struct boardinfo *bi;
588 int status = -ENODEV;
589 int dynamic = 0;
590
591 if (!dev)
592 return -ENODEV;
593
594 /* even if it's just one always-selected device, there must
595 * be at least one chipselect
596 */
597 if (master->num_chipselect == 0)
598 return -EINVAL;
599
600 /* convention: dynamically assigned bus IDs count down from the max */
601 if (master->bus_num < 0) {
602 /* FIXME switch to an IDR based scheme, something like
603 * I2C now uses, so we can't run out of "dynamic" IDs
604 */
605 master->bus_num = atomic_dec_return(&dyn_bus_id);
606 dynamic = 1;
607 }
608
609 spin_lock_init(&master->bus_lock_spinlock);
610 mutex_init(&master->bus_lock_mutex);
611 master->bus_lock_flag = 0;
612
613 /* register the device, then userspace will see it.
614 * registration fails if the bus ID is in use.
615 */
616 dev_set_name(&master->dev, "spi%u", master->bus_num);
617 status = device_add(&master->dev);
618 if (status < 0)
619 goto done;
620 dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
621 dynamic ? " (dynamic)" : "");
622
623 mutex_lock(&board_lock);
624 list_add_tail(&master->list, &spi_master_list);
625 list_for_each_entry(bi, &board_list, list)
626 spi_match_master_to_boardinfo(master, &bi->board_info);
627 mutex_unlock(&board_lock);
628
629 status = 0;
630
631 /* Register devices from the device tree */
632 of_register_spi_devices(master);
633done:
634 return status;
635}
636EXPORT_SYMBOL_GPL(spi_register_master);
637
638
639static int __unregister(struct device *dev, void *null)
640{
641 spi_unregister_device(to_spi_device(dev));
642 return 0;
643}
644
645/**
646 * spi_unregister_master - unregister SPI master controller
647 * @master: the master being unregistered
648 * Context: can sleep
649 *
650 * This call is used only by SPI master controller drivers, which are the
651 * only ones directly touching chip registers.
652 *
653 * This must be called from context that can sleep.
654 */
655void spi_unregister_master(struct spi_master *master)
656{
657 int dummy;
658
659 mutex_lock(&board_lock);
660 list_del(&master->list);
661 mutex_unlock(&board_lock);
662
663 dummy = device_for_each_child(&master->dev, NULL, __unregister);
664 device_unregister(&master->dev);
665}
666EXPORT_SYMBOL_GPL(spi_unregister_master);
667
668static int __spi_master_match(struct device *dev, void *data)
669{
670 struct spi_master *m;
671 u16 *bus_num = data;
672
673 m = container_of(dev, struct spi_master, dev);
674 return m->bus_num == *bus_num;
675}
676
677/**
678 * spi_busnum_to_master - look up master associated with bus_num
679 * @bus_num: the master's bus number
680 * Context: can sleep
681 *
682 * This call may be used with devices that are registered after
683 * arch init time. It returns a refcounted pointer to the relevant
684 * spi_master (which the caller must release), or NULL if there is
685 * no such master registered.
686 */
687struct spi_master *spi_busnum_to_master(u16 bus_num)
688{
689 struct device *dev;
690 struct spi_master *master = NULL;
691
692 dev = class_find_device(&spi_master_class, NULL, &bus_num,
693 __spi_master_match);
694 if (dev)
695 master = container_of(dev, struct spi_master, dev);
696 /* reference got in class_find_device */
697 return master;
698}
699EXPORT_SYMBOL_GPL(spi_busnum_to_master);
700
701
702/*-------------------------------------------------------------------------*/
703
704/* Core methods for SPI master protocol drivers. Some of the
705 * other core methods are currently defined as inline functions.
706 */
707
708/**
709 * spi_setup - setup SPI mode and clock rate
710 * @spi: the device whose settings are being modified
711 * Context: can sleep, and no requests are queued to the device
712 *
713 * SPI protocol drivers may need to update the transfer mode if the
714 * device doesn't work with its default. They may likewise need
715 * to update clock rates or word sizes from initial values. This function
716 * changes those settings, and must be called from a context that can sleep.
717 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
718 * effect the next time the device is selected and data is transferred to
719 * or from it. When this function returns, the spi device is deselected.
720 *
721 * Note that this call will fail if the protocol driver specifies an option
722 * that the underlying controller or its driver does not support. For
723 * example, not all hardware supports wire transfers using nine bit words,
724 * LSB-first wire encoding, or active-high chipselects.
725 */
726int spi_setup(struct spi_device *spi)
727{
728 unsigned bad_bits;
729 int status;
730
731 /* help drivers fail *cleanly* when they need options
732 * that aren't supported with their current master
733 */
734 bad_bits = spi->mode & ~spi->master->mode_bits;
735 if (bad_bits) {
736 dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
737 bad_bits);
738 return -EINVAL;
739 }
740
741 if (!spi->bits_per_word)
742 spi->bits_per_word = 8;
743
744 status = spi->master->setup(spi);
745
746 dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
747 "%u bits/w, %u Hz max --> %d\n",
748 (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
749 (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
750 (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
751 (spi->mode & SPI_3WIRE) ? "3wire, " : "",
752 (spi->mode & SPI_LOOP) ? "loopback, " : "",
753 spi->bits_per_word, spi->max_speed_hz,
754 status);
755
756 return status;
757}
758EXPORT_SYMBOL_GPL(spi_setup);
759
760static int __spi_async(struct spi_device *spi, struct spi_message *message)
761{
762 struct spi_master *master = spi->master;
763
764 /* Half-duplex links include original MicroWire, and ones with
765 * only one data pin like SPI_3WIRE (switches direction) or where
766 * either MOSI or MISO is missing. They can also be caused by
767 * software limitations.
768 */
769 if ((master->flags & SPI_MASTER_HALF_DUPLEX)
770 || (spi->mode & SPI_3WIRE)) {
771 struct spi_transfer *xfer;
772 unsigned flags = master->flags;
773
774 list_for_each_entry(xfer, &message->transfers, transfer_list) {
775 if (xfer->rx_buf && xfer->tx_buf)
776 return -EINVAL;
777 if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
778 return -EINVAL;
779 if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
780 return -EINVAL;
781 }
782 }
783
784 message->spi = spi;
785 message->status = -EINPROGRESS;
786 return master->transfer(spi, message);
787}
788
789/**
790 * spi_async - asynchronous SPI transfer
791 * @spi: device with which data will be exchanged
792 * @message: describes the data transfers, including completion callback
793 * Context: any (irqs may be blocked, etc)
794 *
795 * This call may be used in_irq and other contexts which can't sleep,
796 * as well as from task contexts which can sleep.
797 *
798 * The completion callback is invoked in a context which can't sleep.
799 * Before that invocation, the value of message->status is undefined.
800 * When the callback is issued, message->status holds either zero (to
801 * indicate complete success) or a negative error code. After that
802 * callback returns, the driver which issued the transfer request may
803 * deallocate the associated memory; it's no longer in use by any SPI
804 * core or controller driver code.
805 *
806 * Note that although all messages to a spi_device are handled in
807 * FIFO order, messages may go to different devices in other orders.
808 * Some device might be higher priority, or have various "hard" access
809 * time requirements, for example.
810 *
811 * On detection of any fault during the transfer, processing of
812 * the entire message is aborted, and the device is deselected.
813 * Until returning from the associated message completion callback,
814 * no other spi_message queued to that device will be processed.
815 * (This rule applies equally to all the synchronous transfer calls,
816 * which are wrappers around this core asynchronous primitive.)
817 */
818int spi_async(struct spi_device *spi, struct spi_message *message)
819{
820 struct spi_master *master = spi->master;
821 int ret;
822 unsigned long flags;
823
824 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
825
826 if (master->bus_lock_flag)
827 ret = -EBUSY;
828 else
829 ret = __spi_async(spi, message);
830
831 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
832
833 return ret;
834}
835EXPORT_SYMBOL_GPL(spi_async);
836
837/**
838 * spi_async_locked - version of spi_async with exclusive bus usage
839 * @spi: device with which data will be exchanged
840 * @message: describes the data transfers, including completion callback
841 * Context: any (irqs may be blocked, etc)
842 *
843 * This call may be used in_irq and other contexts which can't sleep,
844 * as well as from task contexts which can sleep.
845 *
846 * The completion callback is invoked in a context which can't sleep.
847 * Before that invocation, the value of message->status is undefined.
848 * When the callback is issued, message->status holds either zero (to
849 * indicate complete success) or a negative error code. After that
850 * callback returns, the driver which issued the transfer request may
851 * deallocate the associated memory; it's no longer in use by any SPI
852 * core or controller driver code.
853 *
854 * Note that although all messages to a spi_device are handled in
855 * FIFO order, messages may go to different devices in other orders.
856 * Some device might be higher priority, or have various "hard" access
857 * time requirements, for example.
858 *
859 * On detection of any fault during the transfer, processing of
860 * the entire message is aborted, and the device is deselected.
861 * Until returning from the associated message completion callback,
862 * no other spi_message queued to that device will be processed.
863 * (This rule applies equally to all the synchronous transfer calls,
864 * which are wrappers around this core asynchronous primitive.)
865 */
866int spi_async_locked(struct spi_device *spi, struct spi_message *message)
867{
868 struct spi_master *master = spi->master;
869 int ret;
870 unsigned long flags;
871
872 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
873
874 ret = __spi_async(spi, message);
875
876 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
877
878 return ret;
879
880}
881EXPORT_SYMBOL_GPL(spi_async_locked);
882
883
884/*-------------------------------------------------------------------------*/
885
886/* Utility methods for SPI master protocol drivers, layered on
887 * top of the core. Some other utility methods are defined as
888 * inline functions.
889 */
890
891static void spi_complete(void *arg)
892{
893 complete(arg);
894}
895
896static int __spi_sync(struct spi_device *spi, struct spi_message *message,
897 int bus_locked)
898{
899 DECLARE_COMPLETION_ONSTACK(done);
900 int status;
901 struct spi_master *master = spi->master;
902
903 message->complete = spi_complete;
904 message->context = &done;
905
906 if (!bus_locked)
907 mutex_lock(&master->bus_lock_mutex);
908
909 status = spi_async_locked(spi, message);
910
911 if (!bus_locked)
912 mutex_unlock(&master->bus_lock_mutex);
913
914 if (status == 0) {
915 wait_for_completion(&done);
916 status = message->status;
917 }
918 message->context = NULL;
919 return status;
920}
921
922/**
923 * spi_sync - blocking/synchronous SPI data transfers
924 * @spi: device with which data will be exchanged
925 * @message: describes the data transfers
926 * Context: can sleep
927 *
928 * This call may only be used from a context that may sleep. The sleep
929 * is non-interruptible, and has no timeout. Low-overhead controller
930 * drivers may DMA directly into and out of the message buffers.
931 *
932 * Note that the SPI device's chip select is active during the message,
933 * and then is normally disabled between messages. Drivers for some
934 * frequently-used devices may want to minimize costs of selecting a chip,
935 * by leaving it selected in anticipation that the next message will go
936 * to the same chip. (That may increase power usage.)
937 *
938 * Also, the caller is guaranteeing that the memory associated with the
939 * message will not be freed before this call returns.
940 *
941 * It returns zero on success, else a negative error code.
942 */
943int spi_sync(struct spi_device *spi, struct spi_message *message)
944{
945 return __spi_sync(spi, message, 0);
946}
947EXPORT_SYMBOL_GPL(spi_sync);
948
949/**
950 * spi_sync_locked - version of spi_sync with exclusive bus usage
951 * @spi: device with which data will be exchanged
952 * @message: describes the data transfers
953 * Context: can sleep
954 *
955 * This call may only be used from a context that may sleep. The sleep
956 * is non-interruptible, and has no timeout. Low-overhead controller
957 * drivers may DMA directly into and out of the message buffers.
958 *
959 * This call should be used by drivers that require exclusive access to the
960 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
961 * be released by a spi_bus_unlock call when the exclusive access is over.
962 *
963 * It returns zero on success, else a negative error code.
964 */
965int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
966{
967 return __spi_sync(spi, message, 1);
968}
969EXPORT_SYMBOL_GPL(spi_sync_locked);
970
971/**
972 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
973 * @master: SPI bus master that should be locked for exclusive bus access
974 * Context: can sleep
975 *
976 * This call may only be used from a context that may sleep. The sleep
977 * is non-interruptible, and has no timeout.
978 *
979 * This call should be used by drivers that require exclusive access to the
980 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
981 * exclusive access is over. Data transfer must be done by spi_sync_locked
982 * and spi_async_locked calls when the SPI bus lock is held.
983 *
984 * It returns zero on success, else a negative error code.
985 */
986int spi_bus_lock(struct spi_master *master)
987{
988 unsigned long flags;
989
990 mutex_lock(&master->bus_lock_mutex);
991
992 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
993 master->bus_lock_flag = 1;
994 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
995
996 /* mutex remains locked until spi_bus_unlock is called */
997
998 return 0;
999}
1000EXPORT_SYMBOL_GPL(spi_bus_lock);
1001
1002/**
1003 * spi_bus_unlock - release the lock for exclusive SPI bus usage
1004 * @master: SPI bus master that was locked for exclusive bus access
1005 * Context: can sleep
1006 *
1007 * This call may only be used from a context that may sleep. The sleep
1008 * is non-interruptible, and has no timeout.
1009 *
1010 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
1011 * call.
1012 *
1013 * It returns zero on success, else a negative error code.
1014 */
1015int spi_bus_unlock(struct spi_master *master)
1016{
1017 master->bus_lock_flag = 0;
1018
1019 mutex_unlock(&master->bus_lock_mutex);
1020
1021 return 0;
1022}
1023EXPORT_SYMBOL_GPL(spi_bus_unlock);
1024
1025/* portable code must never pass more than 32 bytes */
1026#define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
1027
1028static u8 *buf;
1029
1030/**
1031 * spi_write_then_read - SPI synchronous write followed by read
1032 * @spi: device with which data will be exchanged
1033 * @txbuf: data to be written (need not be dma-safe)
1034 * @n_tx: size of txbuf, in bytes
1035 * @rxbuf: buffer into which data will be read (need not be dma-safe)
1036 * @n_rx: size of rxbuf, in bytes
1037 * Context: can sleep
1038 *
1039 * This performs a half duplex MicroWire style transaction with the
1040 * device, sending txbuf and then reading rxbuf. The return value
1041 * is zero for success, else a negative errno status code.
1042 * This call may only be used from a context that may sleep.
1043 *
1044 * Parameters to this routine are always copied using a small buffer;
1045 * portable code should never use this for more than 32 bytes.
1046 * Performance-sensitive or bulk transfer code should instead use
1047 * spi_{async,sync}() calls with dma-safe buffers.
1048 */
1049int spi_write_then_read(struct spi_device *spi,
1050 const void *txbuf, unsigned n_tx,
1051 void *rxbuf, unsigned n_rx)
1052{
1053 static DEFINE_MUTEX(lock);
1054
1055 int status;
1056 struct spi_message message;
1057 struct spi_transfer x[2];
1058 u8 *local_buf;
1059
1060 /* Use preallocated DMA-safe buffer. We can't avoid copying here,
1061 * (as a pure convenience thing), but we can keep heap costs
1062 * out of the hot path ...
1063 */
1064 if ((n_tx + n_rx) > SPI_BUFSIZ)
1065 return -EINVAL;
1066
1067 spi_message_init(&message);
1068 memset(x, 0, sizeof x);
1069 if (n_tx) {
1070 x[0].len = n_tx;
1071 spi_message_add_tail(&x[0], &message);
1072 }
1073 if (n_rx) {
1074 x[1].len = n_rx;
1075 spi_message_add_tail(&x[1], &message);
1076 }
1077
1078 /* ... unless someone else is using the pre-allocated buffer */
1079 if (!mutex_trylock(&lock)) {
1080 local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1081 if (!local_buf)
1082 return -ENOMEM;
1083 } else
1084 local_buf = buf;
1085
1086 memcpy(local_buf, txbuf, n_tx);
1087 x[0].tx_buf = local_buf;
1088 x[1].rx_buf = local_buf + n_tx;
1089
1090 /* do the i/o */
1091 status = spi_sync(spi, &message);
1092 if (status == 0)
1093 memcpy(rxbuf, x[1].rx_buf, n_rx);
1094
1095 if (x[0].tx_buf == buf)
1096 mutex_unlock(&lock);
1097 else
1098 kfree(local_buf);
1099
1100 return status;
1101}
1102EXPORT_SYMBOL_GPL(spi_write_then_read);
1103
1104/*-------------------------------------------------------------------------*/
1105
1106static int __init spi_init(void)
1107{
1108 int status;
1109
1110 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1111 if (!buf) {
1112 status = -ENOMEM;
1113 goto err0;
1114 }
1115
1116 status = bus_register(&spi_bus_type);
1117 if (status < 0)
1118 goto err1;
1119
1120 status = class_register(&spi_master_class);
1121 if (status < 0)
1122 goto err2;
1123 return 0;
1124
1125err2:
1126 bus_unregister(&spi_bus_type);
1127err1:
1128 kfree(buf);
1129 buf = NULL;
1130err0:
1131 return status;
1132}
1133
1134/* board_info is normally registered in arch_initcall(),
1135 * but even essential drivers wait till later
1136 *
1137 * REVISIT only boardinfo really needs static linking. the rest (device and
1138 * driver registration) _could_ be dynamically linked (modular) ... costs
1139 * include needing to have boardinfo data structures be much more public.
1140 */
1141postcore_initcall(spi_init);
1142
1/*
2 * SPI init/core code
3 *
4 * Copyright (C) 2005 David Brownell
5 * Copyright (C) 2008 Secret Lab Technologies Ltd.
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#include <linux/kernel.h>
23#include <linux/kmod.h>
24#include <linux/device.h>
25#include <linux/init.h>
26#include <linux/cache.h>
27#include <linux/mutex.h>
28#include <linux/of_device.h>
29#include <linux/of_irq.h>
30#include <linux/slab.h>
31#include <linux/mod_devicetable.h>
32#include <linux/spi/spi.h>
33#include <linux/pm_runtime.h>
34#include <linux/export.h>
35#include <linux/sched.h>
36#include <linux/delay.h>
37#include <linux/kthread.h>
38
39static void spidev_release(struct device *dev)
40{
41 struct spi_device *spi = to_spi_device(dev);
42
43 /* spi masters may cleanup for released devices */
44 if (spi->master->cleanup)
45 spi->master->cleanup(spi);
46
47 spi_master_put(spi->master);
48 kfree(spi);
49}
50
51static ssize_t
52modalias_show(struct device *dev, struct device_attribute *a, char *buf)
53{
54 const struct spi_device *spi = to_spi_device(dev);
55
56 return sprintf(buf, "%s\n", spi->modalias);
57}
58
59static struct device_attribute spi_dev_attrs[] = {
60 __ATTR_RO(modalias),
61 __ATTR_NULL,
62};
63
64/* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
65 * and the sysfs version makes coldplug work too.
66 */
67
68static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
69 const struct spi_device *sdev)
70{
71 while (id->name[0]) {
72 if (!strcmp(sdev->modalias, id->name))
73 return id;
74 id++;
75 }
76 return NULL;
77}
78
79const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
80{
81 const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
82
83 return spi_match_id(sdrv->id_table, sdev);
84}
85EXPORT_SYMBOL_GPL(spi_get_device_id);
86
87static int spi_match_device(struct device *dev, struct device_driver *drv)
88{
89 const struct spi_device *spi = to_spi_device(dev);
90 const struct spi_driver *sdrv = to_spi_driver(drv);
91
92 /* Attempt an OF style match */
93 if (of_driver_match_device(dev, drv))
94 return 1;
95
96 if (sdrv->id_table)
97 return !!spi_match_id(sdrv->id_table, spi);
98
99 return strcmp(spi->modalias, drv->name) == 0;
100}
101
102static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
103{
104 const struct spi_device *spi = to_spi_device(dev);
105
106 add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
107 return 0;
108}
109
110#ifdef CONFIG_PM_SLEEP
111static int spi_legacy_suspend(struct device *dev, pm_message_t message)
112{
113 int value = 0;
114 struct spi_driver *drv = to_spi_driver(dev->driver);
115
116 /* suspend will stop irqs and dma; no more i/o */
117 if (drv) {
118 if (drv->suspend)
119 value = drv->suspend(to_spi_device(dev), message);
120 else
121 dev_dbg(dev, "... can't suspend\n");
122 }
123 return value;
124}
125
126static int spi_legacy_resume(struct device *dev)
127{
128 int value = 0;
129 struct spi_driver *drv = to_spi_driver(dev->driver);
130
131 /* resume may restart the i/o queue */
132 if (drv) {
133 if (drv->resume)
134 value = drv->resume(to_spi_device(dev));
135 else
136 dev_dbg(dev, "... can't resume\n");
137 }
138 return value;
139}
140
141static int spi_pm_suspend(struct device *dev)
142{
143 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
144
145 if (pm)
146 return pm_generic_suspend(dev);
147 else
148 return spi_legacy_suspend(dev, PMSG_SUSPEND);
149}
150
151static int spi_pm_resume(struct device *dev)
152{
153 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
154
155 if (pm)
156 return pm_generic_resume(dev);
157 else
158 return spi_legacy_resume(dev);
159}
160
161static int spi_pm_freeze(struct device *dev)
162{
163 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
164
165 if (pm)
166 return pm_generic_freeze(dev);
167 else
168 return spi_legacy_suspend(dev, PMSG_FREEZE);
169}
170
171static int spi_pm_thaw(struct device *dev)
172{
173 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
174
175 if (pm)
176 return pm_generic_thaw(dev);
177 else
178 return spi_legacy_resume(dev);
179}
180
181static int spi_pm_poweroff(struct device *dev)
182{
183 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
184
185 if (pm)
186 return pm_generic_poweroff(dev);
187 else
188 return spi_legacy_suspend(dev, PMSG_HIBERNATE);
189}
190
191static int spi_pm_restore(struct device *dev)
192{
193 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
194
195 if (pm)
196 return pm_generic_restore(dev);
197 else
198 return spi_legacy_resume(dev);
199}
200#else
201#define spi_pm_suspend NULL
202#define spi_pm_resume NULL
203#define spi_pm_freeze NULL
204#define spi_pm_thaw NULL
205#define spi_pm_poweroff NULL
206#define spi_pm_restore NULL
207#endif
208
209static const struct dev_pm_ops spi_pm = {
210 .suspend = spi_pm_suspend,
211 .resume = spi_pm_resume,
212 .freeze = spi_pm_freeze,
213 .thaw = spi_pm_thaw,
214 .poweroff = spi_pm_poweroff,
215 .restore = spi_pm_restore,
216 SET_RUNTIME_PM_OPS(
217 pm_generic_runtime_suspend,
218 pm_generic_runtime_resume,
219 pm_generic_runtime_idle
220 )
221};
222
223struct bus_type spi_bus_type = {
224 .name = "spi",
225 .dev_attrs = spi_dev_attrs,
226 .match = spi_match_device,
227 .uevent = spi_uevent,
228 .pm = &spi_pm,
229};
230EXPORT_SYMBOL_GPL(spi_bus_type);
231
232
233static int spi_drv_probe(struct device *dev)
234{
235 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
236
237 return sdrv->probe(to_spi_device(dev));
238}
239
240static int spi_drv_remove(struct device *dev)
241{
242 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
243
244 return sdrv->remove(to_spi_device(dev));
245}
246
247static void spi_drv_shutdown(struct device *dev)
248{
249 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
250
251 sdrv->shutdown(to_spi_device(dev));
252}
253
254/**
255 * spi_register_driver - register a SPI driver
256 * @sdrv: the driver to register
257 * Context: can sleep
258 */
259int spi_register_driver(struct spi_driver *sdrv)
260{
261 sdrv->driver.bus = &spi_bus_type;
262 if (sdrv->probe)
263 sdrv->driver.probe = spi_drv_probe;
264 if (sdrv->remove)
265 sdrv->driver.remove = spi_drv_remove;
266 if (sdrv->shutdown)
267 sdrv->driver.shutdown = spi_drv_shutdown;
268 return driver_register(&sdrv->driver);
269}
270EXPORT_SYMBOL_GPL(spi_register_driver);
271
272/*-------------------------------------------------------------------------*/
273
274/* SPI devices should normally not be created by SPI device drivers; that
275 * would make them board-specific. Similarly with SPI master drivers.
276 * Device registration normally goes into like arch/.../mach.../board-YYY.c
277 * with other readonly (flashable) information about mainboard devices.
278 */
279
280struct boardinfo {
281 struct list_head list;
282 struct spi_board_info board_info;
283};
284
285static LIST_HEAD(board_list);
286static LIST_HEAD(spi_master_list);
287
288/*
289 * Used to protect add/del opertion for board_info list and
290 * spi_master list, and their matching process
291 */
292static DEFINE_MUTEX(board_lock);
293
294/**
295 * spi_alloc_device - Allocate a new SPI device
296 * @master: Controller to which device is connected
297 * Context: can sleep
298 *
299 * Allows a driver to allocate and initialize a spi_device without
300 * registering it immediately. This allows a driver to directly
301 * fill the spi_device with device parameters before calling
302 * spi_add_device() on it.
303 *
304 * Caller is responsible to call spi_add_device() on the returned
305 * spi_device structure to add it to the SPI master. If the caller
306 * needs to discard the spi_device without adding it, then it should
307 * call spi_dev_put() on it.
308 *
309 * Returns a pointer to the new device, or NULL.
310 */
311struct spi_device *spi_alloc_device(struct spi_master *master)
312{
313 struct spi_device *spi;
314 struct device *dev = master->dev.parent;
315
316 if (!spi_master_get(master))
317 return NULL;
318
319 spi = kzalloc(sizeof *spi, GFP_KERNEL);
320 if (!spi) {
321 dev_err(dev, "cannot alloc spi_device\n");
322 spi_master_put(master);
323 return NULL;
324 }
325
326 spi->master = master;
327 spi->dev.parent = &master->dev;
328 spi->dev.bus = &spi_bus_type;
329 spi->dev.release = spidev_release;
330 device_initialize(&spi->dev);
331 return spi;
332}
333EXPORT_SYMBOL_GPL(spi_alloc_device);
334
335/**
336 * spi_add_device - Add spi_device allocated with spi_alloc_device
337 * @spi: spi_device to register
338 *
339 * Companion function to spi_alloc_device. Devices allocated with
340 * spi_alloc_device can be added onto the spi bus with this function.
341 *
342 * Returns 0 on success; negative errno on failure
343 */
344int spi_add_device(struct spi_device *spi)
345{
346 static DEFINE_MUTEX(spi_add_lock);
347 struct device *dev = spi->master->dev.parent;
348 struct device *d;
349 int status;
350
351 /* Chipselects are numbered 0..max; validate. */
352 if (spi->chip_select >= spi->master->num_chipselect) {
353 dev_err(dev, "cs%d >= max %d\n",
354 spi->chip_select,
355 spi->master->num_chipselect);
356 return -EINVAL;
357 }
358
359 /* Set the bus ID string */
360 dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
361 spi->chip_select);
362
363
364 /* We need to make sure there's no other device with this
365 * chipselect **BEFORE** we call setup(), else we'll trash
366 * its configuration. Lock against concurrent add() calls.
367 */
368 mutex_lock(&spi_add_lock);
369
370 d = bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));
371 if (d != NULL) {
372 dev_err(dev, "chipselect %d already in use\n",
373 spi->chip_select);
374 put_device(d);
375 status = -EBUSY;
376 goto done;
377 }
378
379 /* Drivers may modify this initial i/o setup, but will
380 * normally rely on the device being setup. Devices
381 * using SPI_CS_HIGH can't coexist well otherwise...
382 */
383 status = spi_setup(spi);
384 if (status < 0) {
385 dev_err(dev, "can't setup %s, status %d\n",
386 dev_name(&spi->dev), status);
387 goto done;
388 }
389
390 /* Device may be bound to an active driver when this returns */
391 status = device_add(&spi->dev);
392 if (status < 0)
393 dev_err(dev, "can't add %s, status %d\n",
394 dev_name(&spi->dev), status);
395 else
396 dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
397
398done:
399 mutex_unlock(&spi_add_lock);
400 return status;
401}
402EXPORT_SYMBOL_GPL(spi_add_device);
403
404/**
405 * spi_new_device - instantiate one new SPI device
406 * @master: Controller to which device is connected
407 * @chip: Describes the SPI device
408 * Context: can sleep
409 *
410 * On typical mainboards, this is purely internal; and it's not needed
411 * after board init creates the hard-wired devices. Some development
412 * platforms may not be able to use spi_register_board_info though, and
413 * this is exported so that for example a USB or parport based adapter
414 * driver could add devices (which it would learn about out-of-band).
415 *
416 * Returns the new device, or NULL.
417 */
418struct spi_device *spi_new_device(struct spi_master *master,
419 struct spi_board_info *chip)
420{
421 struct spi_device *proxy;
422 int status;
423
424 /* NOTE: caller did any chip->bus_num checks necessary.
425 *
426 * Also, unless we change the return value convention to use
427 * error-or-pointer (not NULL-or-pointer), troubleshootability
428 * suggests syslogged diagnostics are best here (ugh).
429 */
430
431 proxy = spi_alloc_device(master);
432 if (!proxy)
433 return NULL;
434
435 WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
436
437 proxy->chip_select = chip->chip_select;
438 proxy->max_speed_hz = chip->max_speed_hz;
439 proxy->mode = chip->mode;
440 proxy->irq = chip->irq;
441 strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
442 proxy->dev.platform_data = (void *) chip->platform_data;
443 proxy->controller_data = chip->controller_data;
444 proxy->controller_state = NULL;
445
446 status = spi_add_device(proxy);
447 if (status < 0) {
448 spi_dev_put(proxy);
449 return NULL;
450 }
451
452 return proxy;
453}
454EXPORT_SYMBOL_GPL(spi_new_device);
455
456static void spi_match_master_to_boardinfo(struct spi_master *master,
457 struct spi_board_info *bi)
458{
459 struct spi_device *dev;
460
461 if (master->bus_num != bi->bus_num)
462 return;
463
464 dev = spi_new_device(master, bi);
465 if (!dev)
466 dev_err(master->dev.parent, "can't create new device for %s\n",
467 bi->modalias);
468}
469
470/**
471 * spi_register_board_info - register SPI devices for a given board
472 * @info: array of chip descriptors
473 * @n: how many descriptors are provided
474 * Context: can sleep
475 *
476 * Board-specific early init code calls this (probably during arch_initcall)
477 * with segments of the SPI device table. Any device nodes are created later,
478 * after the relevant parent SPI controller (bus_num) is defined. We keep
479 * this table of devices forever, so that reloading a controller driver will
480 * not make Linux forget about these hard-wired devices.
481 *
482 * Other code can also call this, e.g. a particular add-on board might provide
483 * SPI devices through its expansion connector, so code initializing that board
484 * would naturally declare its SPI devices.
485 *
486 * The board info passed can safely be __initdata ... but be careful of
487 * any embedded pointers (platform_data, etc), they're copied as-is.
488 */
489int __devinit
490spi_register_board_info(struct spi_board_info const *info, unsigned n)
491{
492 struct boardinfo *bi;
493 int i;
494
495 bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
496 if (!bi)
497 return -ENOMEM;
498
499 for (i = 0; i < n; i++, bi++, info++) {
500 struct spi_master *master;
501
502 memcpy(&bi->board_info, info, sizeof(*info));
503 mutex_lock(&board_lock);
504 list_add_tail(&bi->list, &board_list);
505 list_for_each_entry(master, &spi_master_list, list)
506 spi_match_master_to_boardinfo(master, &bi->board_info);
507 mutex_unlock(&board_lock);
508 }
509
510 return 0;
511}
512
513/*-------------------------------------------------------------------------*/
514
515/**
516 * spi_pump_messages - kthread work function which processes spi message queue
517 * @work: pointer to kthread work struct contained in the master struct
518 *
519 * This function checks if there is any spi message in the queue that
520 * needs processing and if so call out to the driver to initialize hardware
521 * and transfer each message.
522 *
523 */
524static void spi_pump_messages(struct kthread_work *work)
525{
526 struct spi_master *master =
527 container_of(work, struct spi_master, pump_messages);
528 unsigned long flags;
529 bool was_busy = false;
530 int ret;
531
532 /* Lock queue and check for queue work */
533 spin_lock_irqsave(&master->queue_lock, flags);
534 if (list_empty(&master->queue) || !master->running) {
535 if (master->busy && master->unprepare_transfer_hardware) {
536 ret = master->unprepare_transfer_hardware(master);
537 if (ret) {
538 spin_unlock_irqrestore(&master->queue_lock, flags);
539 dev_err(&master->dev,
540 "failed to unprepare transfer hardware\n");
541 return;
542 }
543 }
544 master->busy = false;
545 spin_unlock_irqrestore(&master->queue_lock, flags);
546 return;
547 }
548
549 /* Make sure we are not already running a message */
550 if (master->cur_msg) {
551 spin_unlock_irqrestore(&master->queue_lock, flags);
552 return;
553 }
554 /* Extract head of queue */
555 master->cur_msg =
556 list_entry(master->queue.next, struct spi_message, queue);
557
558 list_del_init(&master->cur_msg->queue);
559 if (master->busy)
560 was_busy = true;
561 else
562 master->busy = true;
563 spin_unlock_irqrestore(&master->queue_lock, flags);
564
565 if (!was_busy && master->prepare_transfer_hardware) {
566 ret = master->prepare_transfer_hardware(master);
567 if (ret) {
568 dev_err(&master->dev,
569 "failed to prepare transfer hardware\n");
570 return;
571 }
572 }
573
574 ret = master->transfer_one_message(master, master->cur_msg);
575 if (ret) {
576 dev_err(&master->dev,
577 "failed to transfer one message from queue\n");
578 return;
579 }
580}
581
582static int spi_init_queue(struct spi_master *master)
583{
584 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
585
586 INIT_LIST_HEAD(&master->queue);
587 spin_lock_init(&master->queue_lock);
588
589 master->running = false;
590 master->busy = false;
591
592 init_kthread_worker(&master->kworker);
593 master->kworker_task = kthread_run(kthread_worker_fn,
594 &master->kworker,
595 dev_name(&master->dev));
596 if (IS_ERR(master->kworker_task)) {
597 dev_err(&master->dev, "failed to create message pump task\n");
598 return -ENOMEM;
599 }
600 init_kthread_work(&master->pump_messages, spi_pump_messages);
601
602 /*
603 * Master config will indicate if this controller should run the
604 * message pump with high (realtime) priority to reduce the transfer
605 * latency on the bus by minimising the delay between a transfer
606 * request and the scheduling of the message pump thread. Without this
607 * setting the message pump thread will remain at default priority.
608 */
609 if (master->rt) {
610 dev_info(&master->dev,
611 "will run message pump with realtime priority\n");
612 sched_setscheduler(master->kworker_task, SCHED_FIFO, ¶m);
613 }
614
615 return 0;
616}
617
618/**
619 * spi_get_next_queued_message() - called by driver to check for queued
620 * messages
621 * @master: the master to check for queued messages
622 *
623 * If there are more messages in the queue, the next message is returned from
624 * this call.
625 */
626struct spi_message *spi_get_next_queued_message(struct spi_master *master)
627{
628 struct spi_message *next;
629 unsigned long flags;
630
631 /* get a pointer to the next message, if any */
632 spin_lock_irqsave(&master->queue_lock, flags);
633 if (list_empty(&master->queue))
634 next = NULL;
635 else
636 next = list_entry(master->queue.next,
637 struct spi_message, queue);
638 spin_unlock_irqrestore(&master->queue_lock, flags);
639
640 return next;
641}
642EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
643
644/**
645 * spi_finalize_current_message() - the current message is complete
646 * @master: the master to return the message to
647 *
648 * Called by the driver to notify the core that the message in the front of the
649 * queue is complete and can be removed from the queue.
650 */
651void spi_finalize_current_message(struct spi_master *master)
652{
653 struct spi_message *mesg;
654 unsigned long flags;
655
656 spin_lock_irqsave(&master->queue_lock, flags);
657 mesg = master->cur_msg;
658 master->cur_msg = NULL;
659
660 queue_kthread_work(&master->kworker, &master->pump_messages);
661 spin_unlock_irqrestore(&master->queue_lock, flags);
662
663 mesg->state = NULL;
664 if (mesg->complete)
665 mesg->complete(mesg->context);
666}
667EXPORT_SYMBOL_GPL(spi_finalize_current_message);
668
669static int spi_start_queue(struct spi_master *master)
670{
671 unsigned long flags;
672
673 spin_lock_irqsave(&master->queue_lock, flags);
674
675 if (master->running || master->busy) {
676 spin_unlock_irqrestore(&master->queue_lock, flags);
677 return -EBUSY;
678 }
679
680 master->running = true;
681 master->cur_msg = NULL;
682 spin_unlock_irqrestore(&master->queue_lock, flags);
683
684 queue_kthread_work(&master->kworker, &master->pump_messages);
685
686 return 0;
687}
688
689static int spi_stop_queue(struct spi_master *master)
690{
691 unsigned long flags;
692 unsigned limit = 500;
693 int ret = 0;
694
695 spin_lock_irqsave(&master->queue_lock, flags);
696
697 /*
698 * This is a bit lame, but is optimized for the common execution path.
699 * A wait_queue on the master->busy could be used, but then the common
700 * execution path (pump_messages) would be required to call wake_up or
701 * friends on every SPI message. Do this instead.
702 */
703 while ((!list_empty(&master->queue) || master->busy) && limit--) {
704 spin_unlock_irqrestore(&master->queue_lock, flags);
705 msleep(10);
706 spin_lock_irqsave(&master->queue_lock, flags);
707 }
708
709 if (!list_empty(&master->queue) || master->busy)
710 ret = -EBUSY;
711 else
712 master->running = false;
713
714 spin_unlock_irqrestore(&master->queue_lock, flags);
715
716 if (ret) {
717 dev_warn(&master->dev,
718 "could not stop message queue\n");
719 return ret;
720 }
721 return ret;
722}
723
724static int spi_destroy_queue(struct spi_master *master)
725{
726 int ret;
727
728 ret = spi_stop_queue(master);
729
730 /*
731 * flush_kthread_worker will block until all work is done.
732 * If the reason that stop_queue timed out is that the work will never
733 * finish, then it does no good to call flush/stop thread, so
734 * return anyway.
735 */
736 if (ret) {
737 dev_err(&master->dev, "problem destroying queue\n");
738 return ret;
739 }
740
741 flush_kthread_worker(&master->kworker);
742 kthread_stop(master->kworker_task);
743
744 return 0;
745}
746
747/**
748 * spi_queued_transfer - transfer function for queued transfers
749 * @spi: spi device which is requesting transfer
750 * @msg: spi message which is to handled is queued to driver queue
751 */
752static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
753{
754 struct spi_master *master = spi->master;
755 unsigned long flags;
756
757 spin_lock_irqsave(&master->queue_lock, flags);
758
759 if (!master->running) {
760 spin_unlock_irqrestore(&master->queue_lock, flags);
761 return -ESHUTDOWN;
762 }
763 msg->actual_length = 0;
764 msg->status = -EINPROGRESS;
765
766 list_add_tail(&msg->queue, &master->queue);
767 if (master->running && !master->busy)
768 queue_kthread_work(&master->kworker, &master->pump_messages);
769
770 spin_unlock_irqrestore(&master->queue_lock, flags);
771 return 0;
772}
773
774static int spi_master_initialize_queue(struct spi_master *master)
775{
776 int ret;
777
778 master->queued = true;
779 master->transfer = spi_queued_transfer;
780
781 /* Initialize and start queue */
782 ret = spi_init_queue(master);
783 if (ret) {
784 dev_err(&master->dev, "problem initializing queue\n");
785 goto err_init_queue;
786 }
787 ret = spi_start_queue(master);
788 if (ret) {
789 dev_err(&master->dev, "problem starting queue\n");
790 goto err_start_queue;
791 }
792
793 return 0;
794
795err_start_queue:
796err_init_queue:
797 spi_destroy_queue(master);
798 return ret;
799}
800
801/*-------------------------------------------------------------------------*/
802
803#if defined(CONFIG_OF) && !defined(CONFIG_SPARC)
804/**
805 * of_register_spi_devices() - Register child devices onto the SPI bus
806 * @master: Pointer to spi_master device
807 *
808 * Registers an spi_device for each child node of master node which has a 'reg'
809 * property.
810 */
811static void of_register_spi_devices(struct spi_master *master)
812{
813 struct spi_device *spi;
814 struct device_node *nc;
815 const __be32 *prop;
816 int rc;
817 int len;
818
819 if (!master->dev.of_node)
820 return;
821
822 for_each_child_of_node(master->dev.of_node, nc) {
823 /* Alloc an spi_device */
824 spi = spi_alloc_device(master);
825 if (!spi) {
826 dev_err(&master->dev, "spi_device alloc error for %s\n",
827 nc->full_name);
828 spi_dev_put(spi);
829 continue;
830 }
831
832 /* Select device driver */
833 if (of_modalias_node(nc, spi->modalias,
834 sizeof(spi->modalias)) < 0) {
835 dev_err(&master->dev, "cannot find modalias for %s\n",
836 nc->full_name);
837 spi_dev_put(spi);
838 continue;
839 }
840
841 /* Device address */
842 prop = of_get_property(nc, "reg", &len);
843 if (!prop || len < sizeof(*prop)) {
844 dev_err(&master->dev, "%s has no 'reg' property\n",
845 nc->full_name);
846 spi_dev_put(spi);
847 continue;
848 }
849 spi->chip_select = be32_to_cpup(prop);
850
851 /* Mode (clock phase/polarity/etc.) */
852 if (of_find_property(nc, "spi-cpha", NULL))
853 spi->mode |= SPI_CPHA;
854 if (of_find_property(nc, "spi-cpol", NULL))
855 spi->mode |= SPI_CPOL;
856 if (of_find_property(nc, "spi-cs-high", NULL))
857 spi->mode |= SPI_CS_HIGH;
858
859 /* Device speed */
860 prop = of_get_property(nc, "spi-max-frequency", &len);
861 if (!prop || len < sizeof(*prop)) {
862 dev_err(&master->dev, "%s has no 'spi-max-frequency' property\n",
863 nc->full_name);
864 spi_dev_put(spi);
865 continue;
866 }
867 spi->max_speed_hz = be32_to_cpup(prop);
868
869 /* IRQ */
870 spi->irq = irq_of_parse_and_map(nc, 0);
871
872 /* Store a pointer to the node in the device structure */
873 of_node_get(nc);
874 spi->dev.of_node = nc;
875
876 /* Register the new device */
877 request_module(spi->modalias);
878 rc = spi_add_device(spi);
879 if (rc) {
880 dev_err(&master->dev, "spi_device register error %s\n",
881 nc->full_name);
882 spi_dev_put(spi);
883 }
884
885 }
886}
887#else
888static void of_register_spi_devices(struct spi_master *master) { }
889#endif
890
891static void spi_master_release(struct device *dev)
892{
893 struct spi_master *master;
894
895 master = container_of(dev, struct spi_master, dev);
896 kfree(master);
897}
898
899static struct class spi_master_class = {
900 .name = "spi_master",
901 .owner = THIS_MODULE,
902 .dev_release = spi_master_release,
903};
904
905
906
907/**
908 * spi_alloc_master - allocate SPI master controller
909 * @dev: the controller, possibly using the platform_bus
910 * @size: how much zeroed driver-private data to allocate; the pointer to this
911 * memory is in the driver_data field of the returned device,
912 * accessible with spi_master_get_devdata().
913 * Context: can sleep
914 *
915 * This call is used only by SPI master controller drivers, which are the
916 * only ones directly touching chip registers. It's how they allocate
917 * an spi_master structure, prior to calling spi_register_master().
918 *
919 * This must be called from context that can sleep. It returns the SPI
920 * master structure on success, else NULL.
921 *
922 * The caller is responsible for assigning the bus number and initializing
923 * the master's methods before calling spi_register_master(); and (after errors
924 * adding the device) calling spi_master_put() and kfree() to prevent a memory
925 * leak.
926 */
927struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
928{
929 struct spi_master *master;
930
931 if (!dev)
932 return NULL;
933
934 master = kzalloc(size + sizeof *master, GFP_KERNEL);
935 if (!master)
936 return NULL;
937
938 device_initialize(&master->dev);
939 master->bus_num = -1;
940 master->num_chipselect = 1;
941 master->dev.class = &spi_master_class;
942 master->dev.parent = get_device(dev);
943 spi_master_set_devdata(master, &master[1]);
944
945 return master;
946}
947EXPORT_SYMBOL_GPL(spi_alloc_master);
948
949/**
950 * spi_register_master - register SPI master controller
951 * @master: initialized master, originally from spi_alloc_master()
952 * Context: can sleep
953 *
954 * SPI master controllers connect to their drivers using some non-SPI bus,
955 * such as the platform bus. The final stage of probe() in that code
956 * includes calling spi_register_master() to hook up to this SPI bus glue.
957 *
958 * SPI controllers use board specific (often SOC specific) bus numbers,
959 * and board-specific addressing for SPI devices combines those numbers
960 * with chip select numbers. Since SPI does not directly support dynamic
961 * device identification, boards need configuration tables telling which
962 * chip is at which address.
963 *
964 * This must be called from context that can sleep. It returns zero on
965 * success, else a negative error code (dropping the master's refcount).
966 * After a successful return, the caller is responsible for calling
967 * spi_unregister_master().
968 */
969int spi_register_master(struct spi_master *master)
970{
971 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
972 struct device *dev = master->dev.parent;
973 struct boardinfo *bi;
974 int status = -ENODEV;
975 int dynamic = 0;
976
977 if (!dev)
978 return -ENODEV;
979
980 /* even if it's just one always-selected device, there must
981 * be at least one chipselect
982 */
983 if (master->num_chipselect == 0)
984 return -EINVAL;
985
986 /* convention: dynamically assigned bus IDs count down from the max */
987 if (master->bus_num < 0) {
988 /* FIXME switch to an IDR based scheme, something like
989 * I2C now uses, so we can't run out of "dynamic" IDs
990 */
991 master->bus_num = atomic_dec_return(&dyn_bus_id);
992 dynamic = 1;
993 }
994
995 spin_lock_init(&master->bus_lock_spinlock);
996 mutex_init(&master->bus_lock_mutex);
997 master->bus_lock_flag = 0;
998
999 /* register the device, then userspace will see it.
1000 * registration fails if the bus ID is in use.
1001 */
1002 dev_set_name(&master->dev, "spi%u", master->bus_num);
1003 status = device_add(&master->dev);
1004 if (status < 0)
1005 goto done;
1006 dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
1007 dynamic ? " (dynamic)" : "");
1008
1009 /* If we're using a queued driver, start the queue */
1010 if (master->transfer)
1011 dev_info(dev, "master is unqueued, this is deprecated\n");
1012 else {
1013 status = spi_master_initialize_queue(master);
1014 if (status) {
1015 device_unregister(&master->dev);
1016 goto done;
1017 }
1018 }
1019
1020 mutex_lock(&board_lock);
1021 list_add_tail(&master->list, &spi_master_list);
1022 list_for_each_entry(bi, &board_list, list)
1023 spi_match_master_to_boardinfo(master, &bi->board_info);
1024 mutex_unlock(&board_lock);
1025
1026 /* Register devices from the device tree */
1027 of_register_spi_devices(master);
1028done:
1029 return status;
1030}
1031EXPORT_SYMBOL_GPL(spi_register_master);
1032
1033static int __unregister(struct device *dev, void *null)
1034{
1035 spi_unregister_device(to_spi_device(dev));
1036 return 0;
1037}
1038
1039/**
1040 * spi_unregister_master - unregister SPI master controller
1041 * @master: the master being unregistered
1042 * Context: can sleep
1043 *
1044 * This call is used only by SPI master controller drivers, which are the
1045 * only ones directly touching chip registers.
1046 *
1047 * This must be called from context that can sleep.
1048 */
1049void spi_unregister_master(struct spi_master *master)
1050{
1051 int dummy;
1052
1053 if (master->queued) {
1054 if (spi_destroy_queue(master))
1055 dev_err(&master->dev, "queue remove failed\n");
1056 }
1057
1058 mutex_lock(&board_lock);
1059 list_del(&master->list);
1060 mutex_unlock(&board_lock);
1061
1062 dummy = device_for_each_child(&master->dev, NULL, __unregister);
1063 device_unregister(&master->dev);
1064}
1065EXPORT_SYMBOL_GPL(spi_unregister_master);
1066
1067int spi_master_suspend(struct spi_master *master)
1068{
1069 int ret;
1070
1071 /* Basically no-ops for non-queued masters */
1072 if (!master->queued)
1073 return 0;
1074
1075 ret = spi_stop_queue(master);
1076 if (ret)
1077 dev_err(&master->dev, "queue stop failed\n");
1078
1079 return ret;
1080}
1081EXPORT_SYMBOL_GPL(spi_master_suspend);
1082
1083int spi_master_resume(struct spi_master *master)
1084{
1085 int ret;
1086
1087 if (!master->queued)
1088 return 0;
1089
1090 ret = spi_start_queue(master);
1091 if (ret)
1092 dev_err(&master->dev, "queue restart failed\n");
1093
1094 return ret;
1095}
1096EXPORT_SYMBOL_GPL(spi_master_resume);
1097
1098static int __spi_master_match(struct device *dev, void *data)
1099{
1100 struct spi_master *m;
1101 u16 *bus_num = data;
1102
1103 m = container_of(dev, struct spi_master, dev);
1104 return m->bus_num == *bus_num;
1105}
1106
1107/**
1108 * spi_busnum_to_master - look up master associated with bus_num
1109 * @bus_num: the master's bus number
1110 * Context: can sleep
1111 *
1112 * This call may be used with devices that are registered after
1113 * arch init time. It returns a refcounted pointer to the relevant
1114 * spi_master (which the caller must release), or NULL if there is
1115 * no such master registered.
1116 */
1117struct spi_master *spi_busnum_to_master(u16 bus_num)
1118{
1119 struct device *dev;
1120 struct spi_master *master = NULL;
1121
1122 dev = class_find_device(&spi_master_class, NULL, &bus_num,
1123 __spi_master_match);
1124 if (dev)
1125 master = container_of(dev, struct spi_master, dev);
1126 /* reference got in class_find_device */
1127 return master;
1128}
1129EXPORT_SYMBOL_GPL(spi_busnum_to_master);
1130
1131
1132/*-------------------------------------------------------------------------*/
1133
1134/* Core methods for SPI master protocol drivers. Some of the
1135 * other core methods are currently defined as inline functions.
1136 */
1137
1138/**
1139 * spi_setup - setup SPI mode and clock rate
1140 * @spi: the device whose settings are being modified
1141 * Context: can sleep, and no requests are queued to the device
1142 *
1143 * SPI protocol drivers may need to update the transfer mode if the
1144 * device doesn't work with its default. They may likewise need
1145 * to update clock rates or word sizes from initial values. This function
1146 * changes those settings, and must be called from a context that can sleep.
1147 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
1148 * effect the next time the device is selected and data is transferred to
1149 * or from it. When this function returns, the spi device is deselected.
1150 *
1151 * Note that this call will fail if the protocol driver specifies an option
1152 * that the underlying controller or its driver does not support. For
1153 * example, not all hardware supports wire transfers using nine bit words,
1154 * LSB-first wire encoding, or active-high chipselects.
1155 */
1156int spi_setup(struct spi_device *spi)
1157{
1158 unsigned bad_bits;
1159 int status;
1160
1161 /* help drivers fail *cleanly* when they need options
1162 * that aren't supported with their current master
1163 */
1164 bad_bits = spi->mode & ~spi->master->mode_bits;
1165 if (bad_bits) {
1166 dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
1167 bad_bits);
1168 return -EINVAL;
1169 }
1170
1171 if (!spi->bits_per_word)
1172 spi->bits_per_word = 8;
1173
1174 status = spi->master->setup(spi);
1175
1176 dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
1177 "%u bits/w, %u Hz max --> %d\n",
1178 (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
1179 (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
1180 (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
1181 (spi->mode & SPI_3WIRE) ? "3wire, " : "",
1182 (spi->mode & SPI_LOOP) ? "loopback, " : "",
1183 spi->bits_per_word, spi->max_speed_hz,
1184 status);
1185
1186 return status;
1187}
1188EXPORT_SYMBOL_GPL(spi_setup);
1189
1190static int __spi_async(struct spi_device *spi, struct spi_message *message)
1191{
1192 struct spi_master *master = spi->master;
1193
1194 /* Half-duplex links include original MicroWire, and ones with
1195 * only one data pin like SPI_3WIRE (switches direction) or where
1196 * either MOSI or MISO is missing. They can also be caused by
1197 * software limitations.
1198 */
1199 if ((master->flags & SPI_MASTER_HALF_DUPLEX)
1200 || (spi->mode & SPI_3WIRE)) {
1201 struct spi_transfer *xfer;
1202 unsigned flags = master->flags;
1203
1204 list_for_each_entry(xfer, &message->transfers, transfer_list) {
1205 if (xfer->rx_buf && xfer->tx_buf)
1206 return -EINVAL;
1207 if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
1208 return -EINVAL;
1209 if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
1210 return -EINVAL;
1211 }
1212 }
1213
1214 message->spi = spi;
1215 message->status = -EINPROGRESS;
1216 return master->transfer(spi, message);
1217}
1218
1219/**
1220 * spi_async - asynchronous SPI transfer
1221 * @spi: device with which data will be exchanged
1222 * @message: describes the data transfers, including completion callback
1223 * Context: any (irqs may be blocked, etc)
1224 *
1225 * This call may be used in_irq and other contexts which can't sleep,
1226 * as well as from task contexts which can sleep.
1227 *
1228 * The completion callback is invoked in a context which can't sleep.
1229 * Before that invocation, the value of message->status is undefined.
1230 * When the callback is issued, message->status holds either zero (to
1231 * indicate complete success) or a negative error code. After that
1232 * callback returns, the driver which issued the transfer request may
1233 * deallocate the associated memory; it's no longer in use by any SPI
1234 * core or controller driver code.
1235 *
1236 * Note that although all messages to a spi_device are handled in
1237 * FIFO order, messages may go to different devices in other orders.
1238 * Some device might be higher priority, or have various "hard" access
1239 * time requirements, for example.
1240 *
1241 * On detection of any fault during the transfer, processing of
1242 * the entire message is aborted, and the device is deselected.
1243 * Until returning from the associated message completion callback,
1244 * no other spi_message queued to that device will be processed.
1245 * (This rule applies equally to all the synchronous transfer calls,
1246 * which are wrappers around this core asynchronous primitive.)
1247 */
1248int spi_async(struct spi_device *spi, struct spi_message *message)
1249{
1250 struct spi_master *master = spi->master;
1251 int ret;
1252 unsigned long flags;
1253
1254 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1255
1256 if (master->bus_lock_flag)
1257 ret = -EBUSY;
1258 else
1259 ret = __spi_async(spi, message);
1260
1261 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1262
1263 return ret;
1264}
1265EXPORT_SYMBOL_GPL(spi_async);
1266
1267/**
1268 * spi_async_locked - version of spi_async with exclusive bus usage
1269 * @spi: device with which data will be exchanged
1270 * @message: describes the data transfers, including completion callback
1271 * Context: any (irqs may be blocked, etc)
1272 *
1273 * This call may be used in_irq and other contexts which can't sleep,
1274 * as well as from task contexts which can sleep.
1275 *
1276 * The completion callback is invoked in a context which can't sleep.
1277 * Before that invocation, the value of message->status is undefined.
1278 * When the callback is issued, message->status holds either zero (to
1279 * indicate complete success) or a negative error code. After that
1280 * callback returns, the driver which issued the transfer request may
1281 * deallocate the associated memory; it's no longer in use by any SPI
1282 * core or controller driver code.
1283 *
1284 * Note that although all messages to a spi_device are handled in
1285 * FIFO order, messages may go to different devices in other orders.
1286 * Some device might be higher priority, or have various "hard" access
1287 * time requirements, for example.
1288 *
1289 * On detection of any fault during the transfer, processing of
1290 * the entire message is aborted, and the device is deselected.
1291 * Until returning from the associated message completion callback,
1292 * no other spi_message queued to that device will be processed.
1293 * (This rule applies equally to all the synchronous transfer calls,
1294 * which are wrappers around this core asynchronous primitive.)
1295 */
1296int spi_async_locked(struct spi_device *spi, struct spi_message *message)
1297{
1298 struct spi_master *master = spi->master;
1299 int ret;
1300 unsigned long flags;
1301
1302 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1303
1304 ret = __spi_async(spi, message);
1305
1306 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1307
1308 return ret;
1309
1310}
1311EXPORT_SYMBOL_GPL(spi_async_locked);
1312
1313
1314/*-------------------------------------------------------------------------*/
1315
1316/* Utility methods for SPI master protocol drivers, layered on
1317 * top of the core. Some other utility methods are defined as
1318 * inline functions.
1319 */
1320
1321static void spi_complete(void *arg)
1322{
1323 complete(arg);
1324}
1325
1326static int __spi_sync(struct spi_device *spi, struct spi_message *message,
1327 int bus_locked)
1328{
1329 DECLARE_COMPLETION_ONSTACK(done);
1330 int status;
1331 struct spi_master *master = spi->master;
1332
1333 message->complete = spi_complete;
1334 message->context = &done;
1335
1336 if (!bus_locked)
1337 mutex_lock(&master->bus_lock_mutex);
1338
1339 status = spi_async_locked(spi, message);
1340
1341 if (!bus_locked)
1342 mutex_unlock(&master->bus_lock_mutex);
1343
1344 if (status == 0) {
1345 wait_for_completion(&done);
1346 status = message->status;
1347 }
1348 message->context = NULL;
1349 return status;
1350}
1351
1352/**
1353 * spi_sync - blocking/synchronous SPI data transfers
1354 * @spi: device with which data will be exchanged
1355 * @message: describes the data transfers
1356 * Context: can sleep
1357 *
1358 * This call may only be used from a context that may sleep. The sleep
1359 * is non-interruptible, and has no timeout. Low-overhead controller
1360 * drivers may DMA directly into and out of the message buffers.
1361 *
1362 * Note that the SPI device's chip select is active during the message,
1363 * and then is normally disabled between messages. Drivers for some
1364 * frequently-used devices may want to minimize costs of selecting a chip,
1365 * by leaving it selected in anticipation that the next message will go
1366 * to the same chip. (That may increase power usage.)
1367 *
1368 * Also, the caller is guaranteeing that the memory associated with the
1369 * message will not be freed before this call returns.
1370 *
1371 * It returns zero on success, else a negative error code.
1372 */
1373int spi_sync(struct spi_device *spi, struct spi_message *message)
1374{
1375 return __spi_sync(spi, message, 0);
1376}
1377EXPORT_SYMBOL_GPL(spi_sync);
1378
1379/**
1380 * spi_sync_locked - version of spi_sync with exclusive bus usage
1381 * @spi: device with which data will be exchanged
1382 * @message: describes the data transfers
1383 * Context: can sleep
1384 *
1385 * This call may only be used from a context that may sleep. The sleep
1386 * is non-interruptible, and has no timeout. Low-overhead controller
1387 * drivers may DMA directly into and out of the message buffers.
1388 *
1389 * This call should be used by drivers that require exclusive access to the
1390 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
1391 * be released by a spi_bus_unlock call when the exclusive access is over.
1392 *
1393 * It returns zero on success, else a negative error code.
1394 */
1395int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
1396{
1397 return __spi_sync(spi, message, 1);
1398}
1399EXPORT_SYMBOL_GPL(spi_sync_locked);
1400
1401/**
1402 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
1403 * @master: SPI bus master that should be locked for exclusive bus access
1404 * Context: can sleep
1405 *
1406 * This call may only be used from a context that may sleep. The sleep
1407 * is non-interruptible, and has no timeout.
1408 *
1409 * This call should be used by drivers that require exclusive access to the
1410 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
1411 * exclusive access is over. Data transfer must be done by spi_sync_locked
1412 * and spi_async_locked calls when the SPI bus lock is held.
1413 *
1414 * It returns zero on success, else a negative error code.
1415 */
1416int spi_bus_lock(struct spi_master *master)
1417{
1418 unsigned long flags;
1419
1420 mutex_lock(&master->bus_lock_mutex);
1421
1422 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1423 master->bus_lock_flag = 1;
1424 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1425
1426 /* mutex remains locked until spi_bus_unlock is called */
1427
1428 return 0;
1429}
1430EXPORT_SYMBOL_GPL(spi_bus_lock);
1431
1432/**
1433 * spi_bus_unlock - release the lock for exclusive SPI bus usage
1434 * @master: SPI bus master that was locked for exclusive bus access
1435 * Context: can sleep
1436 *
1437 * This call may only be used from a context that may sleep. The sleep
1438 * is non-interruptible, and has no timeout.
1439 *
1440 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
1441 * call.
1442 *
1443 * It returns zero on success, else a negative error code.
1444 */
1445int spi_bus_unlock(struct spi_master *master)
1446{
1447 master->bus_lock_flag = 0;
1448
1449 mutex_unlock(&master->bus_lock_mutex);
1450
1451 return 0;
1452}
1453EXPORT_SYMBOL_GPL(spi_bus_unlock);
1454
1455/* portable code must never pass more than 32 bytes */
1456#define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
1457
1458static u8 *buf;
1459
1460/**
1461 * spi_write_then_read - SPI synchronous write followed by read
1462 * @spi: device with which data will be exchanged
1463 * @txbuf: data to be written (need not be dma-safe)
1464 * @n_tx: size of txbuf, in bytes
1465 * @rxbuf: buffer into which data will be read (need not be dma-safe)
1466 * @n_rx: size of rxbuf, in bytes
1467 * Context: can sleep
1468 *
1469 * This performs a half duplex MicroWire style transaction with the
1470 * device, sending txbuf and then reading rxbuf. The return value
1471 * is zero for success, else a negative errno status code.
1472 * This call may only be used from a context that may sleep.
1473 *
1474 * Parameters to this routine are always copied using a small buffer;
1475 * portable code should never use this for more than 32 bytes.
1476 * Performance-sensitive or bulk transfer code should instead use
1477 * spi_{async,sync}() calls with dma-safe buffers.
1478 */
1479int spi_write_then_read(struct spi_device *spi,
1480 const void *txbuf, unsigned n_tx,
1481 void *rxbuf, unsigned n_rx)
1482{
1483 static DEFINE_MUTEX(lock);
1484
1485 int status;
1486 struct spi_message message;
1487 struct spi_transfer x[2];
1488 u8 *local_buf;
1489
1490 /* Use preallocated DMA-safe buffer. We can't avoid copying here,
1491 * (as a pure convenience thing), but we can keep heap costs
1492 * out of the hot path ...
1493 */
1494 if ((n_tx + n_rx) > SPI_BUFSIZ)
1495 return -EINVAL;
1496
1497 spi_message_init(&message);
1498 memset(x, 0, sizeof x);
1499 if (n_tx) {
1500 x[0].len = n_tx;
1501 spi_message_add_tail(&x[0], &message);
1502 }
1503 if (n_rx) {
1504 x[1].len = n_rx;
1505 spi_message_add_tail(&x[1], &message);
1506 }
1507
1508 /* ... unless someone else is using the pre-allocated buffer */
1509 if (!mutex_trylock(&lock)) {
1510 local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1511 if (!local_buf)
1512 return -ENOMEM;
1513 } else
1514 local_buf = buf;
1515
1516 memcpy(local_buf, txbuf, n_tx);
1517 x[0].tx_buf = local_buf;
1518 x[1].rx_buf = local_buf + n_tx;
1519
1520 /* do the i/o */
1521 status = spi_sync(spi, &message);
1522 if (status == 0)
1523 memcpy(rxbuf, x[1].rx_buf, n_rx);
1524
1525 if (x[0].tx_buf == buf)
1526 mutex_unlock(&lock);
1527 else
1528 kfree(local_buf);
1529
1530 return status;
1531}
1532EXPORT_SYMBOL_GPL(spi_write_then_read);
1533
1534/*-------------------------------------------------------------------------*/
1535
1536static int __init spi_init(void)
1537{
1538 int status;
1539
1540 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1541 if (!buf) {
1542 status = -ENOMEM;
1543 goto err0;
1544 }
1545
1546 status = bus_register(&spi_bus_type);
1547 if (status < 0)
1548 goto err1;
1549
1550 status = class_register(&spi_master_class);
1551 if (status < 0)
1552 goto err2;
1553 return 0;
1554
1555err2:
1556 bus_unregister(&spi_bus_type);
1557err1:
1558 kfree(buf);
1559 buf = NULL;
1560err0:
1561 return status;
1562}
1563
1564/* board_info is normally registered in arch_initcall(),
1565 * but even essential drivers wait till later
1566 *
1567 * REVISIT only boardinfo really needs static linking. the rest (device and
1568 * driver registration) _could_ be dynamically linked (modular) ... costs
1569 * include needing to have boardinfo data structures be much more public.
1570 */
1571postcore_initcall(spi_init);
1572