mach-ux500: enable ARM errata 764369
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / spi / spi.c
blob77eae99af11ce7ee1541816f3e8c99b352b7a241
1 /*
2 * SPI init/core code
4 * Copyright (C) 2005 David Brownell
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.
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.
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.
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>
34 static void spidev_release(struct device *dev)
36 struct spi_device *spi = to_spi_device(dev);
38 /* spi masters may cleanup for released devices */
39 if (spi->master->cleanup)
40 spi->master->cleanup(spi);
42 spi_master_put(spi->master);
43 kfree(spi);
46 static ssize_t
47 modalias_show(struct device *dev, struct device_attribute *a, char *buf)
49 const struct spi_device *spi = to_spi_device(dev);
51 return sprintf(buf, "%s\n", spi->modalias);
54 static struct device_attribute spi_dev_attrs[] = {
55 __ATTR_RO(modalias),
56 __ATTR_NULL,
59 /* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
60 * and the sysfs version makes coldplug work too.
63 static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
64 const struct spi_device *sdev)
66 while (id->name[0]) {
67 if (!strcmp(sdev->modalias, id->name))
68 return id;
69 id++;
71 return NULL;
74 const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
76 const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
78 return spi_match_id(sdrv->id_table, sdev);
80 EXPORT_SYMBOL_GPL(spi_get_device_id);
82 static int spi_match_device(struct device *dev, struct device_driver *drv)
84 const struct spi_device *spi = to_spi_device(dev);
85 const struct spi_driver *sdrv = to_spi_driver(drv);
87 /* Attempt an OF style match */
88 if (of_driver_match_device(dev, drv))
89 return 1;
91 if (sdrv->id_table)
92 return !!spi_match_id(sdrv->id_table, spi);
94 return strcmp(spi->modalias, drv->name) == 0;
97 static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
99 const struct spi_device *spi = to_spi_device(dev);
101 add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
102 return 0;
105 #ifdef CONFIG_PM_SLEEP
106 static int spi_legacy_suspend(struct device *dev, pm_message_t message)
108 int value = 0;
109 struct spi_driver *drv = to_spi_driver(dev->driver);
111 /* suspend will stop irqs and dma; no more i/o */
112 if (drv) {
113 if (drv->suspend)
114 value = drv->suspend(to_spi_device(dev), message);
115 else
116 dev_dbg(dev, "... can't suspend\n");
118 return value;
121 static int spi_legacy_resume(struct device *dev)
123 int value = 0;
124 struct spi_driver *drv = to_spi_driver(dev->driver);
126 /* resume may restart the i/o queue */
127 if (drv) {
128 if (drv->resume)
129 value = drv->resume(to_spi_device(dev));
130 else
131 dev_dbg(dev, "... can't resume\n");
133 return value;
136 static int spi_pm_suspend(struct device *dev)
138 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
140 if (pm)
141 return pm_generic_suspend(dev);
142 else
143 return spi_legacy_suspend(dev, PMSG_SUSPEND);
146 static int spi_pm_resume(struct device *dev)
148 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
150 if (pm)
151 return pm_generic_resume(dev);
152 else
153 return spi_legacy_resume(dev);
156 static int spi_pm_freeze(struct device *dev)
158 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
160 if (pm)
161 return pm_generic_freeze(dev);
162 else
163 return spi_legacy_suspend(dev, PMSG_FREEZE);
166 static int spi_pm_thaw(struct device *dev)
168 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
170 if (pm)
171 return pm_generic_thaw(dev);
172 else
173 return spi_legacy_resume(dev);
176 static int spi_pm_poweroff(struct device *dev)
178 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
180 if (pm)
181 return pm_generic_poweroff(dev);
182 else
183 return spi_legacy_suspend(dev, PMSG_HIBERNATE);
186 static int spi_pm_restore(struct device *dev)
188 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
190 if (pm)
191 return pm_generic_restore(dev);
192 else
193 return spi_legacy_resume(dev);
195 #else
196 #define spi_pm_suspend NULL
197 #define spi_pm_resume NULL
198 #define spi_pm_freeze NULL
199 #define spi_pm_thaw NULL
200 #define spi_pm_poweroff NULL
201 #define spi_pm_restore NULL
202 #endif
204 static const struct dev_pm_ops spi_pm = {
205 .suspend = spi_pm_suspend,
206 .resume = spi_pm_resume,
207 .freeze = spi_pm_freeze,
208 .thaw = spi_pm_thaw,
209 .poweroff = spi_pm_poweroff,
210 .restore = spi_pm_restore,
211 SET_RUNTIME_PM_OPS(
212 pm_generic_runtime_suspend,
213 pm_generic_runtime_resume,
214 pm_generic_runtime_idle
218 struct bus_type spi_bus_type = {
219 .name = "spi",
220 .dev_attrs = spi_dev_attrs,
221 .match = spi_match_device,
222 .uevent = spi_uevent,
223 .pm = &spi_pm,
225 EXPORT_SYMBOL_GPL(spi_bus_type);
228 static int spi_drv_probe(struct device *dev)
230 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
232 return sdrv->probe(to_spi_device(dev));
235 static int spi_drv_remove(struct device *dev)
237 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
239 return sdrv->remove(to_spi_device(dev));
242 static void spi_drv_shutdown(struct device *dev)
244 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
246 sdrv->shutdown(to_spi_device(dev));
250 * spi_register_driver - register a SPI driver
251 * @sdrv: the driver to register
252 * Context: can sleep
254 int spi_register_driver(struct spi_driver *sdrv)
256 sdrv->driver.bus = &spi_bus_type;
257 if (sdrv->probe)
258 sdrv->driver.probe = spi_drv_probe;
259 if (sdrv->remove)
260 sdrv->driver.remove = spi_drv_remove;
261 if (sdrv->shutdown)
262 sdrv->driver.shutdown = spi_drv_shutdown;
263 return driver_register(&sdrv->driver);
265 EXPORT_SYMBOL_GPL(spi_register_driver);
267 /*-------------------------------------------------------------------------*/
269 /* SPI devices should normally not be created by SPI device drivers; that
270 * would make them board-specific. Similarly with SPI master drivers.
271 * Device registration normally goes into like arch/.../mach.../board-YYY.c
272 * with other readonly (flashable) information about mainboard devices.
275 struct boardinfo {
276 struct list_head list;
277 struct spi_board_info board_info;
280 static LIST_HEAD(board_list);
281 static LIST_HEAD(spi_master_list);
284 * Used to protect add/del opertion for board_info list and
285 * spi_master list, and their matching process
287 static DEFINE_MUTEX(board_lock);
290 * spi_alloc_device - Allocate a new SPI device
291 * @master: Controller to which device is connected
292 * Context: can sleep
294 * Allows a driver to allocate and initialize a spi_device without
295 * registering it immediately. This allows a driver to directly
296 * fill the spi_device with device parameters before calling
297 * spi_add_device() on it.
299 * Caller is responsible to call spi_add_device() on the returned
300 * spi_device structure to add it to the SPI master. If the caller
301 * needs to discard the spi_device without adding it, then it should
302 * call spi_dev_put() on it.
304 * Returns a pointer to the new device, or NULL.
306 struct spi_device *spi_alloc_device(struct spi_master *master)
308 struct spi_device *spi;
309 struct device *dev = master->dev.parent;
311 if (!spi_master_get(master))
312 return NULL;
314 spi = kzalloc(sizeof *spi, GFP_KERNEL);
315 if (!spi) {
316 dev_err(dev, "cannot alloc spi_device\n");
317 spi_master_put(master);
318 return NULL;
321 spi->master = master;
322 spi->dev.parent = dev;
323 spi->dev.bus = &spi_bus_type;
324 spi->dev.release = spidev_release;
325 device_initialize(&spi->dev);
326 return spi;
328 EXPORT_SYMBOL_GPL(spi_alloc_device);
331 * spi_add_device - Add spi_device allocated with spi_alloc_device
332 * @spi: spi_device to register
334 * Companion function to spi_alloc_device. Devices allocated with
335 * spi_alloc_device can be added onto the spi bus with this function.
337 * Returns 0 on success; negative errno on failure
339 int spi_add_device(struct spi_device *spi)
341 static DEFINE_MUTEX(spi_add_lock);
342 struct device *dev = spi->master->dev.parent;
343 struct device *d;
344 int status;
346 /* Chipselects are numbered 0..max; validate. */
347 if (spi->chip_select >= spi->master->num_chipselect) {
348 dev_err(dev, "cs%d >= max %d\n",
349 spi->chip_select,
350 spi->master->num_chipselect);
351 return -EINVAL;
354 /* Set the bus ID string */
355 dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
356 spi->chip_select);
359 /* We need to make sure there's no other device with this
360 * chipselect **BEFORE** we call setup(), else we'll trash
361 * its configuration. Lock against concurrent add() calls.
363 mutex_lock(&spi_add_lock);
365 d = bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));
366 if (d != NULL) {
367 dev_err(dev, "chipselect %d already in use\n",
368 spi->chip_select);
369 put_device(d);
370 status = -EBUSY;
371 goto done;
374 /* Drivers may modify this initial i/o setup, but will
375 * normally rely on the device being setup. Devices
376 * using SPI_CS_HIGH can't coexist well otherwise...
378 status = spi_setup(spi);
379 if (status < 0) {
380 dev_err(dev, "can't setup %s, status %d\n",
381 dev_name(&spi->dev), status);
382 goto done;
385 /* Device may be bound to an active driver when this returns */
386 status = device_add(&spi->dev);
387 if (status < 0)
388 dev_err(dev, "can't add %s, status %d\n",
389 dev_name(&spi->dev), status);
390 else
391 dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
393 done:
394 mutex_unlock(&spi_add_lock);
395 return status;
397 EXPORT_SYMBOL_GPL(spi_add_device);
400 * spi_new_device - instantiate one new SPI device
401 * @master: Controller to which device is connected
402 * @chip: Describes the SPI device
403 * Context: can sleep
405 * On typical mainboards, this is purely internal; and it's not needed
406 * after board init creates the hard-wired devices. Some development
407 * platforms may not be able to use spi_register_board_info though, and
408 * this is exported so that for example a USB or parport based adapter
409 * driver could add devices (which it would learn about out-of-band).
411 * Returns the new device, or NULL.
413 struct spi_device *spi_new_device(struct spi_master *master,
414 struct spi_board_info *chip)
416 struct spi_device *proxy;
417 int status;
419 /* NOTE: caller did any chip->bus_num checks necessary.
421 * Also, unless we change the return value convention to use
422 * error-or-pointer (not NULL-or-pointer), troubleshootability
423 * suggests syslogged diagnostics are best here (ugh).
426 proxy = spi_alloc_device(master);
427 if (!proxy)
428 return NULL;
430 WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
432 proxy->chip_select = chip->chip_select;
433 proxy->max_speed_hz = chip->max_speed_hz;
434 proxy->mode = chip->mode;
435 proxy->irq = chip->irq;
436 strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
437 proxy->dev.platform_data = (void *) chip->platform_data;
438 proxy->controller_data = chip->controller_data;
439 proxy->controller_state = NULL;
441 status = spi_add_device(proxy);
442 if (status < 0) {
443 spi_dev_put(proxy);
444 return NULL;
447 return proxy;
449 EXPORT_SYMBOL_GPL(spi_new_device);
451 static void spi_match_master_to_boardinfo(struct spi_master *master,
452 struct spi_board_info *bi)
454 struct spi_device *dev;
456 if (master->bus_num != bi->bus_num)
457 return;
459 dev = spi_new_device(master, bi);
460 if (!dev)
461 dev_err(master->dev.parent, "can't create new device for %s\n",
462 bi->modalias);
466 * spi_register_board_info - register SPI devices for a given board
467 * @info: array of chip descriptors
468 * @n: how many descriptors are provided
469 * Context: can sleep
471 * Board-specific early init code calls this (probably during arch_initcall)
472 * with segments of the SPI device table. Any device nodes are created later,
473 * after the relevant parent SPI controller (bus_num) is defined. We keep
474 * this table of devices forever, so that reloading a controller driver will
475 * not make Linux forget about these hard-wired devices.
477 * Other code can also call this, e.g. a particular add-on board might provide
478 * SPI devices through its expansion connector, so code initializing that board
479 * would naturally declare its SPI devices.
481 * The board info passed can safely be __initdata ... but be careful of
482 * any embedded pointers (platform_data, etc), they're copied as-is.
484 int __init
485 spi_register_board_info(struct spi_board_info const *info, unsigned n)
487 struct boardinfo *bi;
488 int i;
490 bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
491 if (!bi)
492 return -ENOMEM;
494 for (i = 0; i < n; i++, bi++, info++) {
495 struct spi_master *master;
497 memcpy(&bi->board_info, info, sizeof(*info));
498 mutex_lock(&board_lock);
499 list_add_tail(&bi->list, &board_list);
500 list_for_each_entry(master, &spi_master_list, list)
501 spi_match_master_to_boardinfo(master, &bi->board_info);
502 mutex_unlock(&board_lock);
505 return 0;
508 /*-------------------------------------------------------------------------*/
510 static void spi_master_release(struct device *dev)
512 struct spi_master *master;
514 master = container_of(dev, struct spi_master, dev);
515 kfree(master);
518 static struct class spi_master_class = {
519 .name = "spi_master",
520 .owner = THIS_MODULE,
521 .dev_release = spi_master_release,
526 * spi_alloc_master - allocate SPI master controller
527 * @dev: the controller, possibly using the platform_bus
528 * @size: how much zeroed driver-private data to allocate; the pointer to this
529 * memory is in the driver_data field of the returned device,
530 * accessible with spi_master_get_devdata().
531 * Context: can sleep
533 * This call is used only by SPI master controller drivers, which are the
534 * only ones directly touching chip registers. It's how they allocate
535 * an spi_master structure, prior to calling spi_register_master().
537 * This must be called from context that can sleep. It returns the SPI
538 * master structure on success, else NULL.
540 * The caller is responsible for assigning the bus number and initializing
541 * the master's methods before calling spi_register_master(); and (after errors
542 * adding the device) calling spi_master_put() to prevent a memory leak.
544 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
546 struct spi_master *master;
548 if (!dev)
549 return NULL;
551 master = kzalloc(size + sizeof *master, GFP_KERNEL);
552 if (!master)
553 return NULL;
555 device_initialize(&master->dev);
556 master->dev.class = &spi_master_class;
557 master->dev.parent = get_device(dev);
558 spi_master_set_devdata(master, &master[1]);
560 return master;
562 EXPORT_SYMBOL_GPL(spi_alloc_master);
565 * spi_register_master - register SPI master controller
566 * @master: initialized master, originally from spi_alloc_master()
567 * Context: can sleep
569 * SPI master controllers connect to their drivers using some non-SPI bus,
570 * such as the platform bus. The final stage of probe() in that code
571 * includes calling spi_register_master() to hook up to this SPI bus glue.
573 * SPI controllers use board specific (often SOC specific) bus numbers,
574 * and board-specific addressing for SPI devices combines those numbers
575 * with chip select numbers. Since SPI does not directly support dynamic
576 * device identification, boards need configuration tables telling which
577 * chip is at which address.
579 * This must be called from context that can sleep. It returns zero on
580 * success, else a negative error code (dropping the master's refcount).
581 * After a successful return, the caller is responsible for calling
582 * spi_unregister_master().
584 int spi_register_master(struct spi_master *master)
586 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
587 struct device *dev = master->dev.parent;
588 struct boardinfo *bi;
589 int status = -ENODEV;
590 int dynamic = 0;
592 if (!dev)
593 return -ENODEV;
595 /* even if it's just one always-selected device, there must
596 * be at least one chipselect
598 if (master->num_chipselect == 0)
599 return -EINVAL;
601 /* convention: dynamically assigned bus IDs count down from the max */
602 if (master->bus_num < 0) {
603 /* FIXME switch to an IDR based scheme, something like
604 * I2C now uses, so we can't run out of "dynamic" IDs
606 master->bus_num = atomic_dec_return(&dyn_bus_id);
607 dynamic = 1;
610 spin_lock_init(&master->bus_lock_spinlock);
611 mutex_init(&master->bus_lock_mutex);
612 master->bus_lock_flag = 0;
614 /* register the device, then userspace will see it.
615 * registration fails if the bus ID is in use.
617 dev_set_name(&master->dev, "spi%u", master->bus_num);
618 status = device_add(&master->dev);
619 if (status < 0)
620 goto done;
621 dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
622 dynamic ? " (dynamic)" : "");
624 mutex_lock(&board_lock);
625 list_add_tail(&master->list, &spi_master_list);
626 list_for_each_entry(bi, &board_list, list)
627 spi_match_master_to_boardinfo(master, &bi->board_info);
628 mutex_unlock(&board_lock);
630 status = 0;
632 /* Register devices from the device tree */
633 of_register_spi_devices(master);
634 done:
635 return status;
637 EXPORT_SYMBOL_GPL(spi_register_master);
640 static int __unregister(struct device *dev, void *null)
642 spi_unregister_device(to_spi_device(dev));
643 return 0;
647 * spi_unregister_master - unregister SPI master controller
648 * @master: the master being unregistered
649 * Context: can sleep
651 * This call is used only by SPI master controller drivers, which are the
652 * only ones directly touching chip registers.
654 * This must be called from context that can sleep.
656 void spi_unregister_master(struct spi_master *master)
658 int dummy;
660 mutex_lock(&board_lock);
661 list_del(&master->list);
662 mutex_unlock(&board_lock);
664 dummy = device_for_each_child(&master->dev, NULL, __unregister);
665 device_unregister(&master->dev);
667 EXPORT_SYMBOL_GPL(spi_unregister_master);
669 static int __spi_master_match(struct device *dev, void *data)
671 struct spi_master *m;
672 u16 *bus_num = data;
674 m = container_of(dev, struct spi_master, dev);
675 return m->bus_num == *bus_num;
679 * spi_busnum_to_master - look up master associated with bus_num
680 * @bus_num: the master's bus number
681 * Context: can sleep
683 * This call may be used with devices that are registered after
684 * arch init time. It returns a refcounted pointer to the relevant
685 * spi_master (which the caller must release), or NULL if there is
686 * no such master registered.
688 struct spi_master *spi_busnum_to_master(u16 bus_num)
690 struct device *dev;
691 struct spi_master *master = NULL;
693 dev = class_find_device(&spi_master_class, NULL, &bus_num,
694 __spi_master_match);
695 if (dev)
696 master = container_of(dev, struct spi_master, dev);
697 /* reference got in class_find_device */
698 return master;
700 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
703 /*-------------------------------------------------------------------------*/
705 /* Core methods for SPI master protocol drivers. Some of the
706 * other core methods are currently defined as inline functions.
710 * spi_setup - setup SPI mode and clock rate
711 * @spi: the device whose settings are being modified
712 * Context: can sleep, and no requests are queued to the device
714 * SPI protocol drivers may need to update the transfer mode if the
715 * device doesn't work with its default. They may likewise need
716 * to update clock rates or word sizes from initial values. This function
717 * changes those settings, and must be called from a context that can sleep.
718 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
719 * effect the next time the device is selected and data is transferred to
720 * or from it. When this function returns, the spi device is deselected.
722 * Note that this call will fail if the protocol driver specifies an option
723 * that the underlying controller or its driver does not support. For
724 * example, not all hardware supports wire transfers using nine bit words,
725 * LSB-first wire encoding, or active-high chipselects.
727 int spi_setup(struct spi_device *spi)
729 unsigned bad_bits;
730 int status;
732 /* help drivers fail *cleanly* when they need options
733 * that aren't supported with their current master
735 bad_bits = spi->mode & ~spi->master->mode_bits;
736 if (bad_bits) {
737 dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
738 bad_bits);
739 return -EINVAL;
742 if (!spi->bits_per_word)
743 spi->bits_per_word = 8;
745 status = spi->master->setup(spi);
747 dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
748 "%u bits/w, %u Hz max --> %d\n",
749 (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
750 (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
751 (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
752 (spi->mode & SPI_3WIRE) ? "3wire, " : "",
753 (spi->mode & SPI_LOOP) ? "loopback, " : "",
754 spi->bits_per_word, spi->max_speed_hz,
755 status);
757 return status;
759 EXPORT_SYMBOL_GPL(spi_setup);
761 static int __spi_async(struct spi_device *spi, struct spi_message *message)
763 struct spi_master *master = spi->master;
765 /* Half-duplex links include original MicroWire, and ones with
766 * only one data pin like SPI_3WIRE (switches direction) or where
767 * either MOSI or MISO is missing. They can also be caused by
768 * software limitations.
770 if ((master->flags & SPI_MASTER_HALF_DUPLEX)
771 || (spi->mode & SPI_3WIRE)) {
772 struct spi_transfer *xfer;
773 unsigned flags = master->flags;
775 list_for_each_entry(xfer, &message->transfers, transfer_list) {
776 if (xfer->rx_buf && xfer->tx_buf)
777 return -EINVAL;
778 if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
779 return -EINVAL;
780 if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
781 return -EINVAL;
785 message->spi = spi;
786 message->status = -EINPROGRESS;
787 return master->transfer(spi, message);
791 * spi_async - asynchronous SPI transfer
792 * @spi: device with which data will be exchanged
793 * @message: describes the data transfers, including completion callback
794 * Context: any (irqs may be blocked, etc)
796 * This call may be used in_irq and other contexts which can't sleep,
797 * as well as from task contexts which can sleep.
799 * The completion callback is invoked in a context which can't sleep.
800 * Before that invocation, the value of message->status is undefined.
801 * When the callback is issued, message->status holds either zero (to
802 * indicate complete success) or a negative error code. After that
803 * callback returns, the driver which issued the transfer request may
804 * deallocate the associated memory; it's no longer in use by any SPI
805 * core or controller driver code.
807 * Note that although all messages to a spi_device are handled in
808 * FIFO order, messages may go to different devices in other orders.
809 * Some device might be higher priority, or have various "hard" access
810 * time requirements, for example.
812 * On detection of any fault during the transfer, processing of
813 * the entire message is aborted, and the device is deselected.
814 * Until returning from the associated message completion callback,
815 * no other spi_message queued to that device will be processed.
816 * (This rule applies equally to all the synchronous transfer calls,
817 * which are wrappers around this core asynchronous primitive.)
819 int spi_async(struct spi_device *spi, struct spi_message *message)
821 struct spi_master *master = spi->master;
822 int ret;
823 unsigned long flags;
825 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
827 if (master->bus_lock_flag)
828 ret = -EBUSY;
829 else
830 ret = __spi_async(spi, message);
832 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
834 return ret;
836 EXPORT_SYMBOL_GPL(spi_async);
839 * spi_async_locked - version of spi_async with exclusive bus usage
840 * @spi: device with which data will be exchanged
841 * @message: describes the data transfers, including completion callback
842 * Context: any (irqs may be blocked, etc)
844 * This call may be used in_irq and other contexts which can't sleep,
845 * as well as from task contexts which can sleep.
847 * The completion callback is invoked in a context which can't sleep.
848 * Before that invocation, the value of message->status is undefined.
849 * When the callback is issued, message->status holds either zero (to
850 * indicate complete success) or a negative error code. After that
851 * callback returns, the driver which issued the transfer request may
852 * deallocate the associated memory; it's no longer in use by any SPI
853 * core or controller driver code.
855 * Note that although all messages to a spi_device are handled in
856 * FIFO order, messages may go to different devices in other orders.
857 * Some device might be higher priority, or have various "hard" access
858 * time requirements, for example.
860 * On detection of any fault during the transfer, processing of
861 * the entire message is aborted, and the device is deselected.
862 * Until returning from the associated message completion callback,
863 * no other spi_message queued to that device will be processed.
864 * (This rule applies equally to all the synchronous transfer calls,
865 * which are wrappers around this core asynchronous primitive.)
867 int spi_async_locked(struct spi_device *spi, struct spi_message *message)
869 struct spi_master *master = spi->master;
870 int ret;
871 unsigned long flags;
873 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
875 ret = __spi_async(spi, message);
877 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
879 return ret;
882 EXPORT_SYMBOL_GPL(spi_async_locked);
885 /*-------------------------------------------------------------------------*/
887 /* Utility methods for SPI master protocol drivers, layered on
888 * top of the core. Some other utility methods are defined as
889 * inline functions.
892 static void spi_complete(void *arg)
894 complete(arg);
897 static int __spi_sync(struct spi_device *spi, struct spi_message *message,
898 int bus_locked)
900 DECLARE_COMPLETION_ONSTACK(done);
901 int status;
902 struct spi_master *master = spi->master;
904 message->complete = spi_complete;
905 message->context = &done;
907 if (!bus_locked)
908 mutex_lock(&master->bus_lock_mutex);
910 status = spi_async_locked(spi, message);
912 if (!bus_locked)
913 mutex_unlock(&master->bus_lock_mutex);
915 if (status == 0) {
916 wait_for_completion(&done);
917 status = message->status;
919 message->context = NULL;
920 return status;
924 * spi_sync - blocking/synchronous SPI data transfers
925 * @spi: device with which data will be exchanged
926 * @message: describes the data transfers
927 * Context: can sleep
929 * This call may only be used from a context that may sleep. The sleep
930 * is non-interruptible, and has no timeout. Low-overhead controller
931 * drivers may DMA directly into and out of the message buffers.
933 * Note that the SPI device's chip select is active during the message,
934 * and then is normally disabled between messages. Drivers for some
935 * frequently-used devices may want to minimize costs of selecting a chip,
936 * by leaving it selected in anticipation that the next message will go
937 * to the same chip. (That may increase power usage.)
939 * Also, the caller is guaranteeing that the memory associated with the
940 * message will not be freed before this call returns.
942 * It returns zero on success, else a negative error code.
944 int spi_sync(struct spi_device *spi, struct spi_message *message)
946 return __spi_sync(spi, message, 0);
948 EXPORT_SYMBOL_GPL(spi_sync);
951 * spi_sync_locked - version of spi_sync with exclusive bus usage
952 * @spi: device with which data will be exchanged
953 * @message: describes the data transfers
954 * Context: can sleep
956 * This call may only be used from a context that may sleep. The sleep
957 * is non-interruptible, and has no timeout. Low-overhead controller
958 * drivers may DMA directly into and out of the message buffers.
960 * This call should be used by drivers that require exclusive access to the
961 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
962 * be released by a spi_bus_unlock call when the exclusive access is over.
964 * It returns zero on success, else a negative error code.
966 int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
968 return __spi_sync(spi, message, 1);
970 EXPORT_SYMBOL_GPL(spi_sync_locked);
973 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
974 * @master: SPI bus master that should be locked for exclusive bus access
975 * Context: can sleep
977 * This call may only be used from a context that may sleep. The sleep
978 * is non-interruptible, and has no timeout.
980 * This call should be used by drivers that require exclusive access to the
981 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
982 * exclusive access is over. Data transfer must be done by spi_sync_locked
983 * and spi_async_locked calls when the SPI bus lock is held.
985 * It returns zero on success, else a negative error code.
987 int spi_bus_lock(struct spi_master *master)
989 unsigned long flags;
991 mutex_lock(&master->bus_lock_mutex);
993 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
994 master->bus_lock_flag = 1;
995 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
997 /* mutex remains locked until spi_bus_unlock is called */
999 return 0;
1001 EXPORT_SYMBOL_GPL(spi_bus_lock);
1004 * spi_bus_unlock - release the lock for exclusive SPI bus usage
1005 * @master: SPI bus master that was locked for exclusive bus access
1006 * Context: can sleep
1008 * This call may only be used from a context that may sleep. The sleep
1009 * is non-interruptible, and has no timeout.
1011 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
1012 * call.
1014 * It returns zero on success, else a negative error code.
1016 int spi_bus_unlock(struct spi_master *master)
1018 master->bus_lock_flag = 0;
1020 mutex_unlock(&master->bus_lock_mutex);
1022 return 0;
1024 EXPORT_SYMBOL_GPL(spi_bus_unlock);
1026 /* portable code must never pass more than 32 bytes */
1027 #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
1029 static u8 *buf;
1032 * spi_write_then_read - SPI synchronous write followed by read
1033 * @spi: device with which data will be exchanged
1034 * @txbuf: data to be written (need not be dma-safe)
1035 * @n_tx: size of txbuf, in bytes
1036 * @rxbuf: buffer into which data will be read (need not be dma-safe)
1037 * @n_rx: size of rxbuf, in bytes
1038 * Context: can sleep
1040 * This performs a half duplex MicroWire style transaction with the
1041 * device, sending txbuf and then reading rxbuf. The return value
1042 * is zero for success, else a negative errno status code.
1043 * This call may only be used from a context that may sleep.
1045 * Parameters to this routine are always copied using a small buffer;
1046 * portable code should never use this for more than 32 bytes.
1047 * Performance-sensitive or bulk transfer code should instead use
1048 * spi_{async,sync}() calls with dma-safe buffers.
1050 int spi_write_then_read(struct spi_device *spi,
1051 const void *txbuf, unsigned n_tx,
1052 void *rxbuf, unsigned n_rx)
1054 static DEFINE_MUTEX(lock);
1056 int status;
1057 struct spi_message message;
1058 struct spi_transfer x[2];
1059 u8 *local_buf;
1061 /* Use preallocated DMA-safe buffer. We can't avoid copying here,
1062 * (as a pure convenience thing), but we can keep heap costs
1063 * out of the hot path ...
1065 if ((n_tx + n_rx) > SPI_BUFSIZ)
1066 return -EINVAL;
1068 spi_message_init(&message);
1069 memset(x, 0, sizeof x);
1070 if (n_tx) {
1071 x[0].len = n_tx;
1072 spi_message_add_tail(&x[0], &message);
1074 if (n_rx) {
1075 x[1].len = n_rx;
1076 spi_message_add_tail(&x[1], &message);
1079 /* ... unless someone else is using the pre-allocated buffer */
1080 if (!mutex_trylock(&lock)) {
1081 local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1082 if (!local_buf)
1083 return -ENOMEM;
1084 } else
1085 local_buf = buf;
1087 memcpy(local_buf, txbuf, n_tx);
1088 x[0].tx_buf = local_buf;
1089 x[1].rx_buf = local_buf + n_tx;
1091 /* do the i/o */
1092 status = spi_sync(spi, &message);
1093 if (status == 0)
1094 memcpy(rxbuf, x[1].rx_buf, n_rx);
1096 if (x[0].tx_buf == buf)
1097 mutex_unlock(&lock);
1098 else
1099 kfree(local_buf);
1101 return status;
1103 EXPORT_SYMBOL_GPL(spi_write_then_read);
1105 /*-------------------------------------------------------------------------*/
1107 static int __init spi_init(void)
1109 int status;
1111 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1112 if (!buf) {
1113 status = -ENOMEM;
1114 goto err0;
1117 status = bus_register(&spi_bus_type);
1118 if (status < 0)
1119 goto err1;
1121 status = class_register(&spi_master_class);
1122 if (status < 0)
1123 goto err2;
1124 return 0;
1126 err2:
1127 bus_unregister(&spi_bus_type);
1128 err1:
1129 kfree(buf);
1130 buf = NULL;
1131 err0:
1132 return status;
1135 /* board_info is normally registered in arch_initcall(),
1136 * but even essential drivers wait till later
1138 * REVISIT only boardinfo really needs static linking. the rest (device and
1139 * driver registration) _could_ be dynamically linked (modular) ... costs
1140 * include needing to have boardinfo data structures be much more public.
1142 postcore_initcall(spi_init);