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>
33 #include <linux/sched.h>
34 #include <linux/delay.h>
35 #include <linux/kthread.h>
37 static void spidev_release(struct device *dev)
39 struct spi_device *spi = to_spi_device(dev);
41 /* spi masters may cleanup for released devices */
42 if (spi->master->cleanup)
43 spi->master->cleanup(spi);
45 spi_master_put(spi->master);
50 modalias_show(struct device *dev, struct device_attribute *a, char *buf)
52 const struct spi_device *spi = to_spi_device(dev);
54 return sprintf(buf, "%s\n", spi->modalias);
57 static struct device_attribute spi_dev_attrs[] = {
62 /* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
63 * and the sysfs version makes coldplug work too.
66 static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
67 const struct spi_device *sdev)
70 if (!strcmp(sdev->modalias, id->name))
77 const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
79 const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
81 return spi_match_id(sdrv->id_table, sdev);
83 EXPORT_SYMBOL_GPL(spi_get_device_id);
85 static int spi_match_device(struct device *dev, struct device_driver *drv)
87 const struct spi_device *spi = to_spi_device(dev);
88 const struct spi_driver *sdrv = to_spi_driver(drv);
90 /* Attempt an OF style match */
91 if (of_driver_match_device(dev, drv))
95 return !!spi_match_id(sdrv->id_table, spi);
97 return strcmp(spi->modalias, drv->name) == 0;
100 static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
102 const struct spi_device *spi = to_spi_device(dev);
104 add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
108 #ifdef CONFIG_PM_SLEEP
109 static int spi_legacy_suspend(struct device *dev, pm_message_t message)
112 struct spi_driver *drv = to_spi_driver(dev->driver);
114 /* suspend will stop irqs and dma; no more i/o */
117 value = drv->suspend(to_spi_device(dev), message);
119 dev_dbg(dev, "... can't suspend\n");
124 static int spi_legacy_resume(struct device *dev)
127 struct spi_driver *drv = to_spi_driver(dev->driver);
129 /* resume may restart the i/o queue */
132 value = drv->resume(to_spi_device(dev));
134 dev_dbg(dev, "... can't resume\n");
139 static int spi_pm_suspend(struct device *dev)
141 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
144 return pm_generic_suspend(dev);
146 return spi_legacy_suspend(dev, PMSG_SUSPEND);
149 static int spi_pm_resume(struct device *dev)
151 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
154 return pm_generic_resume(dev);
156 return spi_legacy_resume(dev);
159 static int spi_pm_freeze(struct device *dev)
161 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
164 return pm_generic_freeze(dev);
166 return spi_legacy_suspend(dev, PMSG_FREEZE);
169 static int spi_pm_thaw(struct device *dev)
171 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
174 return pm_generic_thaw(dev);
176 return spi_legacy_resume(dev);
179 static int spi_pm_poweroff(struct device *dev)
181 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
184 return pm_generic_poweroff(dev);
186 return spi_legacy_suspend(dev, PMSG_HIBERNATE);
189 static int spi_pm_restore(struct device *dev)
191 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
194 return pm_generic_restore(dev);
196 return spi_legacy_resume(dev);
199 #define spi_pm_suspend NULL
200 #define spi_pm_resume NULL
201 #define spi_pm_freeze NULL
202 #define spi_pm_thaw NULL
203 #define spi_pm_poweroff NULL
204 #define spi_pm_restore NULL
207 static const struct dev_pm_ops spi_pm = {
208 .suspend = spi_pm_suspend,
209 .resume = spi_pm_resume,
210 .freeze = spi_pm_freeze,
212 .poweroff = spi_pm_poweroff,
213 .restore = spi_pm_restore,
215 pm_generic_runtime_suspend,
216 pm_generic_runtime_resume,
217 pm_generic_runtime_idle
221 struct bus_type spi_bus_type = {
223 .dev_attrs = spi_dev_attrs,
224 .match = spi_match_device,
225 .uevent = spi_uevent,
228 EXPORT_SYMBOL_GPL(spi_bus_type);
231 static int spi_drv_probe(struct device *dev)
233 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
235 return sdrv->probe(to_spi_device(dev));
238 static int spi_drv_remove(struct device *dev)
240 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
242 return sdrv->remove(to_spi_device(dev));
245 static void spi_drv_shutdown(struct device *dev)
247 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
249 sdrv->shutdown(to_spi_device(dev));
253 * spi_register_driver - register a SPI driver
254 * @sdrv: the driver to register
257 int spi_register_driver(struct spi_driver *sdrv)
259 sdrv->driver.bus = &spi_bus_type;
261 sdrv->driver.probe = spi_drv_probe;
263 sdrv->driver.remove = spi_drv_remove;
265 sdrv->driver.shutdown = spi_drv_shutdown;
266 return driver_register(&sdrv->driver);
268 EXPORT_SYMBOL_GPL(spi_register_driver);
270 /*-------------------------------------------------------------------------*/
272 /* SPI devices should normally not be created by SPI device drivers; that
273 * would make them board-specific. Similarly with SPI master drivers.
274 * Device registration normally goes into like arch/.../mach.../board-YYY.c
275 * with other readonly (flashable) information about mainboard devices.
279 struct list_head list;
280 struct spi_board_info board_info;
283 static LIST_HEAD(board_list);
284 static LIST_HEAD(spi_master_list);
287 * Used to protect add/del opertion for board_info list and
288 * spi_master list, and their matching process
290 static DEFINE_MUTEX(board_lock);
293 * spi_alloc_device - Allocate a new SPI device
294 * @master: Controller to which device is connected
297 * Allows a driver to allocate and initialize a spi_device without
298 * registering it immediately. This allows a driver to directly
299 * fill the spi_device with device parameters before calling
300 * spi_add_device() on it.
302 * Caller is responsible to call spi_add_device() on the returned
303 * spi_device structure to add it to the SPI master. If the caller
304 * needs to discard the spi_device without adding it, then it should
305 * call spi_dev_put() on it.
307 * Returns a pointer to the new device, or NULL.
309 struct spi_device *spi_alloc_device(struct spi_master *master)
311 struct spi_device *spi;
312 struct device *dev = master->dev.parent;
314 if (!spi_master_get(master))
317 spi = kzalloc(sizeof *spi, GFP_KERNEL);
319 dev_err(dev, "cannot alloc spi_device\n");
320 spi_master_put(master);
324 spi->master = master;
325 spi->dev.parent = &master->dev;
326 spi->dev.bus = &spi_bus_type;
327 spi->dev.release = spidev_release;
328 device_initialize(&spi->dev);
331 EXPORT_SYMBOL_GPL(spi_alloc_device);
334 * spi_add_device - Add spi_device allocated with spi_alloc_device
335 * @spi: spi_device to register
337 * Companion function to spi_alloc_device. Devices allocated with
338 * spi_alloc_device can be added onto the spi bus with this function.
340 * Returns 0 on success; negative errno on failure
342 int spi_add_device(struct spi_device *spi)
344 static DEFINE_MUTEX(spi_add_lock);
345 struct device *dev = spi->master->dev.parent;
349 /* Chipselects are numbered 0..max; validate. */
350 if (spi->chip_select >= spi->master->num_chipselect) {
351 dev_err(dev, "cs%d >= max %d\n",
353 spi->master->num_chipselect);
357 /* Set the bus ID string */
358 dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
362 /* We need to make sure there's no other device with this
363 * chipselect **BEFORE** we call setup(), else we'll trash
364 * its configuration. Lock against concurrent add() calls.
366 mutex_lock(&spi_add_lock);
368 d = bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));
370 dev_err(dev, "chipselect %d already in use\n",
377 /* Drivers may modify this initial i/o setup, but will
378 * normally rely on the device being setup. Devices
379 * using SPI_CS_HIGH can't coexist well otherwise...
381 status = spi_setup(spi);
383 dev_err(dev, "can't setup %s, status %d\n",
384 dev_name(&spi->dev), status);
388 /* Device may be bound to an active driver when this returns */
389 status = device_add(&spi->dev);
391 dev_err(dev, "can't add %s, status %d\n",
392 dev_name(&spi->dev), status);
394 dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
397 mutex_unlock(&spi_add_lock);
400 EXPORT_SYMBOL_GPL(spi_add_device);
403 * spi_new_device - instantiate one new SPI device
404 * @master: Controller to which device is connected
405 * @chip: Describes the SPI device
408 * On typical mainboards, this is purely internal; and it's not needed
409 * after board init creates the hard-wired devices. Some development
410 * platforms may not be able to use spi_register_board_info though, and
411 * this is exported so that for example a USB or parport based adapter
412 * driver could add devices (which it would learn about out-of-band).
414 * Returns the new device, or NULL.
416 struct spi_device *spi_new_device(struct spi_master *master,
417 struct spi_board_info *chip)
419 struct spi_device *proxy;
422 /* NOTE: caller did any chip->bus_num checks necessary.
424 * Also, unless we change the return value convention to use
425 * error-or-pointer (not NULL-or-pointer), troubleshootability
426 * suggests syslogged diagnostics are best here (ugh).
429 proxy = spi_alloc_device(master);
433 WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
435 proxy->chip_select = chip->chip_select;
436 proxy->max_speed_hz = chip->max_speed_hz;
437 proxy->mode = chip->mode;
438 proxy->irq = chip->irq;
439 strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
440 proxy->dev.platform_data = (void *) chip->platform_data;
441 proxy->controller_data = chip->controller_data;
442 proxy->controller_state = NULL;
444 status = spi_add_device(proxy);
452 EXPORT_SYMBOL_GPL(spi_new_device);
454 static void spi_match_master_to_boardinfo(struct spi_master *master,
455 struct spi_board_info *bi)
457 struct spi_device *dev;
459 if (master->bus_num != bi->bus_num)
462 dev = spi_new_device(master, bi);
464 dev_err(master->dev.parent, "can't create new device for %s\n",
469 * spi_register_board_info - register SPI devices for a given board
470 * @info: array of chip descriptors
471 * @n: how many descriptors are provided
474 * Board-specific early init code calls this (probably during arch_initcall)
475 * with segments of the SPI device table. Any device nodes are created later,
476 * after the relevant parent SPI controller (bus_num) is defined. We keep
477 * this table of devices forever, so that reloading a controller driver will
478 * not make Linux forget about these hard-wired devices.
480 * Other code can also call this, e.g. a particular add-on board might provide
481 * SPI devices through its expansion connector, so code initializing that board
482 * would naturally declare its SPI devices.
484 * The board info passed can safely be __initdata ... but be careful of
485 * any embedded pointers (platform_data, etc), they're copied as-is.
488 spi_register_board_info(struct spi_board_info const *info, unsigned n)
490 struct boardinfo *bi;
493 bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
497 for (i = 0; i < n; i++, bi++, info++) {
498 struct spi_master *master;
500 memcpy(&bi->board_info, info, sizeof(*info));
501 mutex_lock(&board_lock);
502 list_add_tail(&bi->list, &board_list);
503 list_for_each_entry(master, &spi_master_list, list)
504 spi_match_master_to_boardinfo(master, &bi->board_info);
505 mutex_unlock(&board_lock);
511 /*-------------------------------------------------------------------------*/
514 * spi_pump_messages - kthread work function which processes spi message queue
515 * @work: pointer to kthread work struct contained in the master struct
517 * This function checks if there is any spi message in the queue that
518 * needs processing and if so call out to the driver to initialize hardware
519 * and transfer each message.
522 static void spi_pump_messages(struct kthread_work *work)
524 struct spi_master *master =
525 container_of(work, struct spi_master, pump_messages);
527 bool was_busy = false;
530 /* Lock queue and check for queue work */
531 spin_lock_irqsave(&master->queue_lock, flags);
532 if (list_empty(&master->queue) || !master->running) {
534 ret = master->unprepare_transfer_hardware(master);
536 dev_err(&master->dev,
537 "failed to unprepare transfer hardware\n");
541 master->busy = false;
542 spin_unlock_irqrestore(&master->queue_lock, flags);
546 /* Make sure we are not already running a message */
547 if (master->cur_msg) {
548 spin_unlock_irqrestore(&master->queue_lock, flags);
551 /* Extract head of queue */
553 list_entry(master->queue.next, struct spi_message, queue);
555 list_del_init(&master->cur_msg->queue);
560 spin_unlock_irqrestore(&master->queue_lock, flags);
563 ret = master->prepare_transfer_hardware(master);
565 dev_err(&master->dev,
566 "failed to prepare transfer hardware\n");
571 ret = master->transfer_one_message(master, master->cur_msg);
573 dev_err(&master->dev,
574 "failed to transfer one message from queue\n");
579 static int spi_init_queue(struct spi_master *master)
581 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
583 INIT_LIST_HEAD(&master->queue);
584 spin_lock_init(&master->queue_lock);
586 master->running = false;
587 master->busy = false;
589 init_kthread_worker(&master->kworker);
590 master->kworker_task = kthread_run(kthread_worker_fn,
592 dev_name(&master->dev));
593 if (IS_ERR(master->kworker_task)) {
594 dev_err(&master->dev, "failed to create message pump task\n");
597 init_kthread_work(&master->pump_messages, spi_pump_messages);
600 * Master config will indicate if this controller should run the
601 * message pump with high (realtime) priority to reduce the transfer
602 * latency on the bus by minimising the delay between a transfer
603 * request and the scheduling of the message pump thread. Without this
604 * setting the message pump thread will remain at default priority.
607 dev_info(&master->dev,
608 "will run message pump with realtime priority\n");
609 sched_setscheduler(master->kworker_task, SCHED_FIFO, ¶m);
616 * spi_get_next_queued_message() - called by driver to check for queued
618 * @master: the master to check for queued messages
620 * If there are more messages in the queue, the next message is returned from
623 struct spi_message *spi_get_next_queued_message(struct spi_master *master)
625 struct spi_message *next;
628 /* get a pointer to the next message, if any */
629 spin_lock_irqsave(&master->queue_lock, flags);
630 if (list_empty(&master->queue))
633 next = list_entry(master->queue.next,
634 struct spi_message, queue);
635 spin_unlock_irqrestore(&master->queue_lock, flags);
639 EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
642 * spi_finalize_current_message() - the current message is complete
643 * @master: the master to return the message to
645 * Called by the driver to notify the core that the message in the front of the
646 * queue is complete and can be removed from the queue.
648 void spi_finalize_current_message(struct spi_master *master)
650 struct spi_message *mesg;
653 spin_lock_irqsave(&master->queue_lock, flags);
654 mesg = master->cur_msg;
655 master->cur_msg = NULL;
657 queue_kthread_work(&master->kworker, &master->pump_messages);
658 spin_unlock_irqrestore(&master->queue_lock, flags);
662 mesg->complete(mesg->context);
664 EXPORT_SYMBOL_GPL(spi_finalize_current_message);
666 static int spi_start_queue(struct spi_master *master)
670 spin_lock_irqsave(&master->queue_lock, flags);
672 if (master->running || master->busy) {
673 spin_unlock_irqrestore(&master->queue_lock, flags);
677 master->running = true;
678 master->cur_msg = NULL;
679 spin_unlock_irqrestore(&master->queue_lock, flags);
681 queue_kthread_work(&master->kworker, &master->pump_messages);
686 static int spi_stop_queue(struct spi_master *master)
689 unsigned limit = 500;
692 spin_lock_irqsave(&master->queue_lock, flags);
695 * This is a bit lame, but is optimized for the common execution path.
696 * A wait_queue on the master->busy could be used, but then the common
697 * execution path (pump_messages) would be required to call wake_up or
698 * friends on every SPI message. Do this instead.
700 while ((!list_empty(&master->queue) || master->busy) && limit--) {
701 spin_unlock_irqrestore(&master->queue_lock, flags);
703 spin_lock_irqsave(&master->queue_lock, flags);
706 if (!list_empty(&master->queue) || master->busy)
709 master->running = false;
711 spin_unlock_irqrestore(&master->queue_lock, flags);
714 dev_warn(&master->dev,
715 "could not stop message queue\n");
721 static int spi_destroy_queue(struct spi_master *master)
725 ret = spi_stop_queue(master);
728 * flush_kthread_worker will block until all work is done.
729 * If the reason that stop_queue timed out is that the work will never
730 * finish, then it does no good to call flush/stop thread, so
734 dev_err(&master->dev, "problem destroying queue\n");
738 flush_kthread_worker(&master->kworker);
739 kthread_stop(master->kworker_task);
745 * spi_queued_transfer - transfer function for queued transfers
746 * @spi: spi device which is requesting transfer
747 * @msg: spi message which is to handled is queued to driver queue
749 static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
751 struct spi_master *master = spi->master;
754 spin_lock_irqsave(&master->queue_lock, flags);
756 if (!master->running) {
757 spin_unlock_irqrestore(&master->queue_lock, flags);
760 msg->actual_length = 0;
761 msg->status = -EINPROGRESS;
763 list_add_tail(&msg->queue, &master->queue);
764 if (master->running && !master->busy)
765 queue_kthread_work(&master->kworker, &master->pump_messages);
767 spin_unlock_irqrestore(&master->queue_lock, flags);
771 static int spi_master_initialize_queue(struct spi_master *master)
775 master->queued = true;
776 master->transfer = spi_queued_transfer;
778 /* Initialize and start queue */
779 ret = spi_init_queue(master);
781 dev_err(&master->dev, "problem initializing queue\n");
784 ret = spi_start_queue(master);
786 dev_err(&master->dev, "problem starting queue\n");
787 goto err_start_queue;
794 spi_destroy_queue(master);
798 /*-------------------------------------------------------------------------*/
800 static void spi_master_release(struct device *dev)
802 struct spi_master *master;
804 master = container_of(dev, struct spi_master, dev);
808 static struct class spi_master_class = {
809 .name = "spi_master",
810 .owner = THIS_MODULE,
811 .dev_release = spi_master_release,
817 * spi_alloc_master - allocate SPI master controller
818 * @dev: the controller, possibly using the platform_bus
819 * @size: how much zeroed driver-private data to allocate; the pointer to this
820 * memory is in the driver_data field of the returned device,
821 * accessible with spi_master_get_devdata().
824 * This call is used only by SPI master controller drivers, which are the
825 * only ones directly touching chip registers. It's how they allocate
826 * an spi_master structure, prior to calling spi_register_master().
828 * This must be called from context that can sleep. It returns the SPI
829 * master structure on success, else NULL.
831 * The caller is responsible for assigning the bus number and initializing
832 * the master's methods before calling spi_register_master(); and (after errors
833 * adding the device) calling spi_master_put() and kfree() to prevent a memory
836 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
838 struct spi_master *master;
843 master = kzalloc(size + sizeof *master, GFP_KERNEL);
847 device_initialize(&master->dev);
848 master->dev.class = &spi_master_class;
849 master->dev.parent = get_device(dev);
850 spi_master_set_devdata(master, &master[1]);
854 EXPORT_SYMBOL_GPL(spi_alloc_master);
857 * spi_register_master - register SPI master controller
858 * @master: initialized master, originally from spi_alloc_master()
861 * SPI master controllers connect to their drivers using some non-SPI bus,
862 * such as the platform bus. The final stage of probe() in that code
863 * includes calling spi_register_master() to hook up to this SPI bus glue.
865 * SPI controllers use board specific (often SOC specific) bus numbers,
866 * and board-specific addressing for SPI devices combines those numbers
867 * with chip select numbers. Since SPI does not directly support dynamic
868 * device identification, boards need configuration tables telling which
869 * chip is at which address.
871 * This must be called from context that can sleep. It returns zero on
872 * success, else a negative error code (dropping the master's refcount).
873 * After a successful return, the caller is responsible for calling
874 * spi_unregister_master().
876 int spi_register_master(struct spi_master *master)
878 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
879 struct device *dev = master->dev.parent;
880 struct boardinfo *bi;
881 int status = -ENODEV;
887 /* even if it's just one always-selected device, there must
888 * be at least one chipselect
890 if (master->num_chipselect == 0)
893 /* convention: dynamically assigned bus IDs count down from the max */
894 if (master->bus_num < 0) {
895 /* FIXME switch to an IDR based scheme, something like
896 * I2C now uses, so we can't run out of "dynamic" IDs
898 master->bus_num = atomic_dec_return(&dyn_bus_id);
902 spin_lock_init(&master->bus_lock_spinlock);
903 mutex_init(&master->bus_lock_mutex);
904 master->bus_lock_flag = 0;
906 /* register the device, then userspace will see it.
907 * registration fails if the bus ID is in use.
909 dev_set_name(&master->dev, "spi%u", master->bus_num);
910 status = device_add(&master->dev);
913 dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
914 dynamic ? " (dynamic)" : "");
916 /* If we're using a queued driver, start the queue */
917 if (master->transfer)
918 dev_info(dev, "master is unqueued, this is deprecated\n");
920 status = spi_master_initialize_queue(master);
922 device_unregister(&master->dev);
927 mutex_lock(&board_lock);
928 list_add_tail(&master->list, &spi_master_list);
929 list_for_each_entry(bi, &board_list, list)
930 spi_match_master_to_boardinfo(master, &bi->board_info);
931 mutex_unlock(&board_lock);
935 /* Register devices from the device tree */
936 of_register_spi_devices(master);
940 EXPORT_SYMBOL_GPL(spi_register_master);
942 static int __unregister(struct device *dev, void *null)
944 spi_unregister_device(to_spi_device(dev));
949 * spi_unregister_master - unregister SPI master controller
950 * @master: the master being unregistered
953 * This call is used only by SPI master controller drivers, which are the
954 * only ones directly touching chip registers.
956 * This must be called from context that can sleep.
958 void spi_unregister_master(struct spi_master *master)
962 if (master->queued) {
963 if (spi_destroy_queue(master))
964 dev_err(&master->dev, "queue remove failed\n");
967 mutex_lock(&board_lock);
968 list_del(&master->list);
969 mutex_unlock(&board_lock);
971 dummy = device_for_each_child(&master->dev, NULL, __unregister);
972 device_unregister(&master->dev);
974 EXPORT_SYMBOL_GPL(spi_unregister_master);
976 int spi_master_suspend(struct spi_master *master)
980 /* Basically no-ops for non-queued masters */
984 ret = spi_stop_queue(master);
986 dev_err(&master->dev, "queue stop failed\n");
990 EXPORT_SYMBOL_GPL(spi_master_suspend);
992 int spi_master_resume(struct spi_master *master)
999 ret = spi_start_queue(master);
1001 dev_err(&master->dev, "queue restart failed\n");
1005 EXPORT_SYMBOL_GPL(spi_master_resume);
1007 static int __spi_master_match(struct device *dev, void *data)
1009 struct spi_master *m;
1010 u16 *bus_num = data;
1012 m = container_of(dev, struct spi_master, dev);
1013 return m->bus_num == *bus_num;
1017 * spi_busnum_to_master - look up master associated with bus_num
1018 * @bus_num: the master's bus number
1019 * Context: can sleep
1021 * This call may be used with devices that are registered after
1022 * arch init time. It returns a refcounted pointer to the relevant
1023 * spi_master (which the caller must release), or NULL if there is
1024 * no such master registered.
1026 struct spi_master *spi_busnum_to_master(u16 bus_num)
1029 struct spi_master *master = NULL;
1031 dev = class_find_device(&spi_master_class, NULL, &bus_num,
1032 __spi_master_match);
1034 master = container_of(dev, struct spi_master, dev);
1035 /* reference got in class_find_device */
1038 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
1041 /*-------------------------------------------------------------------------*/
1043 /* Core methods for SPI master protocol drivers. Some of the
1044 * other core methods are currently defined as inline functions.
1048 * spi_setup - setup SPI mode and clock rate
1049 * @spi: the device whose settings are being modified
1050 * Context: can sleep, and no requests are queued to the device
1052 * SPI protocol drivers may need to update the transfer mode if the
1053 * device doesn't work with its default. They may likewise need
1054 * to update clock rates or word sizes from initial values. This function
1055 * changes those settings, and must be called from a context that can sleep.
1056 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
1057 * effect the next time the device is selected and data is transferred to
1058 * or from it. When this function returns, the spi device is deselected.
1060 * Note that this call will fail if the protocol driver specifies an option
1061 * that the underlying controller or its driver does not support. For
1062 * example, not all hardware supports wire transfers using nine bit words,
1063 * LSB-first wire encoding, or active-high chipselects.
1065 int spi_setup(struct spi_device *spi)
1070 /* help drivers fail *cleanly* when they need options
1071 * that aren't supported with their current master
1073 bad_bits = spi->mode & ~spi->master->mode_bits;
1075 dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
1080 if (!spi->bits_per_word)
1081 spi->bits_per_word = 8;
1083 status = spi->master->setup(spi);
1085 dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
1086 "%u bits/w, %u Hz max --> %d\n",
1087 (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
1088 (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
1089 (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
1090 (spi->mode & SPI_3WIRE) ? "3wire, " : "",
1091 (spi->mode & SPI_LOOP) ? "loopback, " : "",
1092 spi->bits_per_word, spi->max_speed_hz,
1097 EXPORT_SYMBOL_GPL(spi_setup);
1099 static int __spi_async(struct spi_device *spi, struct spi_message *message)
1101 struct spi_master *master = spi->master;
1103 /* Half-duplex links include original MicroWire, and ones with
1104 * only one data pin like SPI_3WIRE (switches direction) or where
1105 * either MOSI or MISO is missing. They can also be caused by
1106 * software limitations.
1108 if ((master->flags & SPI_MASTER_HALF_DUPLEX)
1109 || (spi->mode & SPI_3WIRE)) {
1110 struct spi_transfer *xfer;
1111 unsigned flags = master->flags;
1113 list_for_each_entry(xfer, &message->transfers, transfer_list) {
1114 if (xfer->rx_buf && xfer->tx_buf)
1116 if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
1118 if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
1124 message->status = -EINPROGRESS;
1125 return master->transfer(spi, message);
1129 * spi_async - asynchronous SPI transfer
1130 * @spi: device with which data will be exchanged
1131 * @message: describes the data transfers, including completion callback
1132 * Context: any (irqs may be blocked, etc)
1134 * This call may be used in_irq and other contexts which can't sleep,
1135 * as well as from task contexts which can sleep.
1137 * The completion callback is invoked in a context which can't sleep.
1138 * Before that invocation, the value of message->status is undefined.
1139 * When the callback is issued, message->status holds either zero (to
1140 * indicate complete success) or a negative error code. After that
1141 * callback returns, the driver which issued the transfer request may
1142 * deallocate the associated memory; it's no longer in use by any SPI
1143 * core or controller driver code.
1145 * Note that although all messages to a spi_device are handled in
1146 * FIFO order, messages may go to different devices in other orders.
1147 * Some device might be higher priority, or have various "hard" access
1148 * time requirements, for example.
1150 * On detection of any fault during the transfer, processing of
1151 * the entire message is aborted, and the device is deselected.
1152 * Until returning from the associated message completion callback,
1153 * no other spi_message queued to that device will be processed.
1154 * (This rule applies equally to all the synchronous transfer calls,
1155 * which are wrappers around this core asynchronous primitive.)
1157 int spi_async(struct spi_device *spi, struct spi_message *message)
1159 struct spi_master *master = spi->master;
1161 unsigned long flags;
1163 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1165 if (master->bus_lock_flag)
1168 ret = __spi_async(spi, message);
1170 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1174 EXPORT_SYMBOL_GPL(spi_async);
1177 * spi_async_locked - version of spi_async with exclusive bus usage
1178 * @spi: device with which data will be exchanged
1179 * @message: describes the data transfers, including completion callback
1180 * Context: any (irqs may be blocked, etc)
1182 * This call may be used in_irq and other contexts which can't sleep,
1183 * as well as from task contexts which can sleep.
1185 * The completion callback is invoked in a context which can't sleep.
1186 * Before that invocation, the value of message->status is undefined.
1187 * When the callback is issued, message->status holds either zero (to
1188 * indicate complete success) or a negative error code. After that
1189 * callback returns, the driver which issued the transfer request may
1190 * deallocate the associated memory; it's no longer in use by any SPI
1191 * core or controller driver code.
1193 * Note that although all messages to a spi_device are handled in
1194 * FIFO order, messages may go to different devices in other orders.
1195 * Some device might be higher priority, or have various "hard" access
1196 * time requirements, for example.
1198 * On detection of any fault during the transfer, processing of
1199 * the entire message is aborted, and the device is deselected.
1200 * Until returning from the associated message completion callback,
1201 * no other spi_message queued to that device will be processed.
1202 * (This rule applies equally to all the synchronous transfer calls,
1203 * which are wrappers around this core asynchronous primitive.)
1205 int spi_async_locked(struct spi_device *spi, struct spi_message *message)
1207 struct spi_master *master = spi->master;
1209 unsigned long flags;
1211 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1213 ret = __spi_async(spi, message);
1215 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1220 EXPORT_SYMBOL_GPL(spi_async_locked);
1223 /*-------------------------------------------------------------------------*/
1225 /* Utility methods for SPI master protocol drivers, layered on
1226 * top of the core. Some other utility methods are defined as
1230 static void spi_complete(void *arg)
1235 static int __spi_sync(struct spi_device *spi, struct spi_message *message,
1238 DECLARE_COMPLETION_ONSTACK(done);
1240 struct spi_master *master = spi->master;
1242 message->complete = spi_complete;
1243 message->context = &done;
1246 mutex_lock(&master->bus_lock_mutex);
1248 status = spi_async_locked(spi, message);
1251 mutex_unlock(&master->bus_lock_mutex);
1254 wait_for_completion(&done);
1255 status = message->status;
1257 message->context = NULL;
1262 * spi_sync - blocking/synchronous SPI data transfers
1263 * @spi: device with which data will be exchanged
1264 * @message: describes the data transfers
1265 * Context: can sleep
1267 * This call may only be used from a context that may sleep. The sleep
1268 * is non-interruptible, and has no timeout. Low-overhead controller
1269 * drivers may DMA directly into and out of the message buffers.
1271 * Note that the SPI device's chip select is active during the message,
1272 * and then is normally disabled between messages. Drivers for some
1273 * frequently-used devices may want to minimize costs of selecting a chip,
1274 * by leaving it selected in anticipation that the next message will go
1275 * to the same chip. (That may increase power usage.)
1277 * Also, the caller is guaranteeing that the memory associated with the
1278 * message will not be freed before this call returns.
1280 * It returns zero on success, else a negative error code.
1282 int spi_sync(struct spi_device *spi, struct spi_message *message)
1284 return __spi_sync(spi, message, 0);
1286 EXPORT_SYMBOL_GPL(spi_sync);
1289 * spi_sync_locked - version of spi_sync with exclusive bus usage
1290 * @spi: device with which data will be exchanged
1291 * @message: describes the data transfers
1292 * Context: can sleep
1294 * This call may only be used from a context that may sleep. The sleep
1295 * is non-interruptible, and has no timeout. Low-overhead controller
1296 * drivers may DMA directly into and out of the message buffers.
1298 * This call should be used by drivers that require exclusive access to the
1299 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
1300 * be released by a spi_bus_unlock call when the exclusive access is over.
1302 * It returns zero on success, else a negative error code.
1304 int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
1306 return __spi_sync(spi, message, 1);
1308 EXPORT_SYMBOL_GPL(spi_sync_locked);
1311 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
1312 * @master: SPI bus master that should be locked for exclusive bus access
1313 * Context: can sleep
1315 * This call may only be used from a context that may sleep. The sleep
1316 * is non-interruptible, and has no timeout.
1318 * This call should be used by drivers that require exclusive access to the
1319 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
1320 * exclusive access is over. Data transfer must be done by spi_sync_locked
1321 * and spi_async_locked calls when the SPI bus lock is held.
1323 * It returns zero on success, else a negative error code.
1325 int spi_bus_lock(struct spi_master *master)
1327 unsigned long flags;
1329 mutex_lock(&master->bus_lock_mutex);
1331 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1332 master->bus_lock_flag = 1;
1333 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1335 /* mutex remains locked until spi_bus_unlock is called */
1339 EXPORT_SYMBOL_GPL(spi_bus_lock);
1342 * spi_bus_unlock - release the lock for exclusive SPI bus usage
1343 * @master: SPI bus master that was locked for exclusive bus access
1344 * Context: can sleep
1346 * This call may only be used from a context that may sleep. The sleep
1347 * is non-interruptible, and has no timeout.
1349 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
1352 * It returns zero on success, else a negative error code.
1354 int spi_bus_unlock(struct spi_master *master)
1356 master->bus_lock_flag = 0;
1358 mutex_unlock(&master->bus_lock_mutex);
1362 EXPORT_SYMBOL_GPL(spi_bus_unlock);
1364 /* portable code must never pass more than 32 bytes */
1365 #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
1370 * spi_write_then_read - SPI synchronous write followed by read
1371 * @spi: device with which data will be exchanged
1372 * @txbuf: data to be written (need not be dma-safe)
1373 * @n_tx: size of txbuf, in bytes
1374 * @rxbuf: buffer into which data will be read (need not be dma-safe)
1375 * @n_rx: size of rxbuf, in bytes
1376 * Context: can sleep
1378 * This performs a half duplex MicroWire style transaction with the
1379 * device, sending txbuf and then reading rxbuf. The return value
1380 * is zero for success, else a negative errno status code.
1381 * This call may only be used from a context that may sleep.
1383 * Parameters to this routine are always copied using a small buffer;
1384 * portable code should never use this for more than 32 bytes.
1385 * Performance-sensitive or bulk transfer code should instead use
1386 * spi_{async,sync}() calls with dma-safe buffers.
1388 int spi_write_then_read(struct spi_device *spi,
1389 const void *txbuf, unsigned n_tx,
1390 void *rxbuf, unsigned n_rx)
1392 static DEFINE_MUTEX(lock);
1395 struct spi_message message;
1396 struct spi_transfer x[2];
1399 /* Use preallocated DMA-safe buffer. We can't avoid copying here,
1400 * (as a pure convenience thing), but we can keep heap costs
1401 * out of the hot path ...
1403 if ((n_tx + n_rx) > SPI_BUFSIZ)
1406 spi_message_init(&message);
1407 memset(x, 0, sizeof x);
1410 spi_message_add_tail(&x[0], &message);
1414 spi_message_add_tail(&x[1], &message);
1417 /* ... unless someone else is using the pre-allocated buffer */
1418 if (!mutex_trylock(&lock)) {
1419 local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1425 memcpy(local_buf, txbuf, n_tx);
1426 x[0].tx_buf = local_buf;
1427 x[1].rx_buf = local_buf + n_tx;
1430 status = spi_sync(spi, &message);
1432 memcpy(rxbuf, x[1].rx_buf, n_rx);
1434 if (x[0].tx_buf == buf)
1435 mutex_unlock(&lock);
1441 EXPORT_SYMBOL_GPL(spi_write_then_read);
1443 /*-------------------------------------------------------------------------*/
1445 static int __init spi_init(void)
1449 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1455 status = bus_register(&spi_bus_type);
1459 status = class_register(&spi_master_class);
1465 bus_unregister(&spi_bus_type);
1473 /* board_info is normally registered in arch_initcall(),
1474 * but even essential drivers wait till later
1476 * REVISIT only boardinfo really needs static linking. the rest (device and
1477 * driver registration) _could_ be dynamically linked (modular) ... costs
1478 * include needing to have boardinfo data structures be much more public.
1480 postcore_initcall(spi_init);