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 spin_unlock_irqrestore(&master->queue_lock, flags);
537 dev_err(&master->dev,
538 "failed to unprepare transfer hardware\n");
542 master->busy = false;
543 spin_unlock_irqrestore(&master->queue_lock, flags);
547 /* Make sure we are not already running a message */
548 if (master->cur_msg) {
549 spin_unlock_irqrestore(&master->queue_lock, flags);
552 /* Extract head of queue */
554 list_entry(master->queue.next, struct spi_message, queue);
556 list_del_init(&master->cur_msg->queue);
561 spin_unlock_irqrestore(&master->queue_lock, flags);
564 ret = master->prepare_transfer_hardware(master);
566 dev_err(&master->dev,
567 "failed to prepare transfer hardware\n");
572 ret = master->transfer_one_message(master, master->cur_msg);
574 dev_err(&master->dev,
575 "failed to transfer one message from queue\n");
580 static int spi_init_queue(struct spi_master *master)
582 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
584 INIT_LIST_HEAD(&master->queue);
585 spin_lock_init(&master->queue_lock);
587 master->running = false;
588 master->busy = false;
590 init_kthread_worker(&master->kworker);
591 master->kworker_task = kthread_run(kthread_worker_fn,
593 dev_name(&master->dev));
594 if (IS_ERR(master->kworker_task)) {
595 dev_err(&master->dev, "failed to create message pump task\n");
598 init_kthread_work(&master->pump_messages, spi_pump_messages);
601 * Master config will indicate if this controller should run the
602 * message pump with high (realtime) priority to reduce the transfer
603 * latency on the bus by minimising the delay between a transfer
604 * request and the scheduling of the message pump thread. Without this
605 * setting the message pump thread will remain at default priority.
608 dev_info(&master->dev,
609 "will run message pump with realtime priority\n");
610 sched_setscheduler(master->kworker_task, SCHED_FIFO, ¶m);
617 * spi_get_next_queued_message() - called by driver to check for queued
619 * @master: the master to check for queued messages
621 * If there are more messages in the queue, the next message is returned from
624 struct spi_message *spi_get_next_queued_message(struct spi_master *master)
626 struct spi_message *next;
629 /* get a pointer to the next message, if any */
630 spin_lock_irqsave(&master->queue_lock, flags);
631 if (list_empty(&master->queue))
634 next = list_entry(master->queue.next,
635 struct spi_message, queue);
636 spin_unlock_irqrestore(&master->queue_lock, flags);
640 EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
643 * spi_finalize_current_message() - the current message is complete
644 * @master: the master to return the message to
646 * Called by the driver to notify the core that the message in the front of the
647 * queue is complete and can be removed from the queue.
649 void spi_finalize_current_message(struct spi_master *master)
651 struct spi_message *mesg;
654 spin_lock_irqsave(&master->queue_lock, flags);
655 mesg = master->cur_msg;
656 master->cur_msg = NULL;
658 queue_kthread_work(&master->kworker, &master->pump_messages);
659 spin_unlock_irqrestore(&master->queue_lock, flags);
663 mesg->complete(mesg->context);
665 EXPORT_SYMBOL_GPL(spi_finalize_current_message);
667 static int spi_start_queue(struct spi_master *master)
671 spin_lock_irqsave(&master->queue_lock, flags);
673 if (master->running || master->busy) {
674 spin_unlock_irqrestore(&master->queue_lock, flags);
678 master->running = true;
679 master->cur_msg = NULL;
680 spin_unlock_irqrestore(&master->queue_lock, flags);
682 queue_kthread_work(&master->kworker, &master->pump_messages);
687 static int spi_stop_queue(struct spi_master *master)
690 unsigned limit = 500;
693 spin_lock_irqsave(&master->queue_lock, flags);
696 * This is a bit lame, but is optimized for the common execution path.
697 * A wait_queue on the master->busy could be used, but then the common
698 * execution path (pump_messages) would be required to call wake_up or
699 * friends on every SPI message. Do this instead.
701 while ((!list_empty(&master->queue) || master->busy) && limit--) {
702 spin_unlock_irqrestore(&master->queue_lock, flags);
704 spin_lock_irqsave(&master->queue_lock, flags);
707 if (!list_empty(&master->queue) || master->busy)
710 master->running = false;
712 spin_unlock_irqrestore(&master->queue_lock, flags);
715 dev_warn(&master->dev,
716 "could not stop message queue\n");
722 static int spi_destroy_queue(struct spi_master *master)
726 ret = spi_stop_queue(master);
729 * flush_kthread_worker will block until all work is done.
730 * If the reason that stop_queue timed out is that the work will never
731 * finish, then it does no good to call flush/stop thread, so
735 dev_err(&master->dev, "problem destroying queue\n");
739 flush_kthread_worker(&master->kworker);
740 kthread_stop(master->kworker_task);
746 * spi_queued_transfer - transfer function for queued transfers
747 * @spi: spi device which is requesting transfer
748 * @msg: spi message which is to handled is queued to driver queue
750 static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
752 struct spi_master *master = spi->master;
755 spin_lock_irqsave(&master->queue_lock, flags);
757 if (!master->running) {
758 spin_unlock_irqrestore(&master->queue_lock, flags);
761 msg->actual_length = 0;
762 msg->status = -EINPROGRESS;
764 list_add_tail(&msg->queue, &master->queue);
765 if (master->running && !master->busy)
766 queue_kthread_work(&master->kworker, &master->pump_messages);
768 spin_unlock_irqrestore(&master->queue_lock, flags);
772 static int spi_master_initialize_queue(struct spi_master *master)
776 master->queued = true;
777 master->transfer = spi_queued_transfer;
779 /* Initialize and start queue */
780 ret = spi_init_queue(master);
782 dev_err(&master->dev, "problem initializing queue\n");
785 ret = spi_start_queue(master);
787 dev_err(&master->dev, "problem starting queue\n");
788 goto err_start_queue;
795 spi_destroy_queue(master);
799 /*-------------------------------------------------------------------------*/
801 static void spi_master_release(struct device *dev)
803 struct spi_master *master;
805 master = container_of(dev, struct spi_master, dev);
809 static struct class spi_master_class = {
810 .name = "spi_master",
811 .owner = THIS_MODULE,
812 .dev_release = spi_master_release,
818 * spi_alloc_master - allocate SPI master controller
819 * @dev: the controller, possibly using the platform_bus
820 * @size: how much zeroed driver-private data to allocate; the pointer to this
821 * memory is in the driver_data field of the returned device,
822 * accessible with spi_master_get_devdata().
825 * This call is used only by SPI master controller drivers, which are the
826 * only ones directly touching chip registers. It's how they allocate
827 * an spi_master structure, prior to calling spi_register_master().
829 * This must be called from context that can sleep. It returns the SPI
830 * master structure on success, else NULL.
832 * The caller is responsible for assigning the bus number and initializing
833 * the master's methods before calling spi_register_master(); and (after errors
834 * adding the device) calling spi_master_put() and kfree() to prevent a memory
837 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
839 struct spi_master *master;
844 master = kzalloc(size + sizeof *master, GFP_KERNEL);
848 device_initialize(&master->dev);
849 master->dev.class = &spi_master_class;
850 master->dev.parent = get_device(dev);
851 spi_master_set_devdata(master, &master[1]);
855 EXPORT_SYMBOL_GPL(spi_alloc_master);
858 * spi_register_master - register SPI master controller
859 * @master: initialized master, originally from spi_alloc_master()
862 * SPI master controllers connect to their drivers using some non-SPI bus,
863 * such as the platform bus. The final stage of probe() in that code
864 * includes calling spi_register_master() to hook up to this SPI bus glue.
866 * SPI controllers use board specific (often SOC specific) bus numbers,
867 * and board-specific addressing for SPI devices combines those numbers
868 * with chip select numbers. Since SPI does not directly support dynamic
869 * device identification, boards need configuration tables telling which
870 * chip is at which address.
872 * This must be called from context that can sleep. It returns zero on
873 * success, else a negative error code (dropping the master's refcount).
874 * After a successful return, the caller is responsible for calling
875 * spi_unregister_master().
877 int spi_register_master(struct spi_master *master)
879 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
880 struct device *dev = master->dev.parent;
881 struct boardinfo *bi;
882 int status = -ENODEV;
888 /* even if it's just one always-selected device, there must
889 * be at least one chipselect
891 if (master->num_chipselect == 0)
894 /* convention: dynamically assigned bus IDs count down from the max */
895 if (master->bus_num < 0) {
896 /* FIXME switch to an IDR based scheme, something like
897 * I2C now uses, so we can't run out of "dynamic" IDs
899 master->bus_num = atomic_dec_return(&dyn_bus_id);
903 spin_lock_init(&master->bus_lock_spinlock);
904 mutex_init(&master->bus_lock_mutex);
905 master->bus_lock_flag = 0;
907 /* register the device, then userspace will see it.
908 * registration fails if the bus ID is in use.
910 dev_set_name(&master->dev, "spi%u", master->bus_num);
911 status = device_add(&master->dev);
914 dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
915 dynamic ? " (dynamic)" : "");
917 /* If we're using a queued driver, start the queue */
918 if (master->transfer)
919 dev_info(dev, "master is unqueued, this is deprecated\n");
921 status = spi_master_initialize_queue(master);
923 device_unregister(&master->dev);
928 mutex_lock(&board_lock);
929 list_add_tail(&master->list, &spi_master_list);
930 list_for_each_entry(bi, &board_list, list)
931 spi_match_master_to_boardinfo(master, &bi->board_info);
932 mutex_unlock(&board_lock);
934 /* Register devices from the device tree */
935 of_register_spi_devices(master);
939 EXPORT_SYMBOL_GPL(spi_register_master);
941 static int __unregister(struct device *dev, void *null)
943 spi_unregister_device(to_spi_device(dev));
948 * spi_unregister_master - unregister SPI master controller
949 * @master: the master being unregistered
952 * This call is used only by SPI master controller drivers, which are the
953 * only ones directly touching chip registers.
955 * This must be called from context that can sleep.
957 void spi_unregister_master(struct spi_master *master)
961 if (master->queued) {
962 if (spi_destroy_queue(master))
963 dev_err(&master->dev, "queue remove failed\n");
966 mutex_lock(&board_lock);
967 list_del(&master->list);
968 mutex_unlock(&board_lock);
970 dummy = device_for_each_child(&master->dev, NULL, __unregister);
971 device_unregister(&master->dev);
973 EXPORT_SYMBOL_GPL(spi_unregister_master);
975 int spi_master_suspend(struct spi_master *master)
979 /* Basically no-ops for non-queued masters */
983 ret = spi_stop_queue(master);
985 dev_err(&master->dev, "queue stop failed\n");
989 EXPORT_SYMBOL_GPL(spi_master_suspend);
991 int spi_master_resume(struct spi_master *master)
998 ret = spi_start_queue(master);
1000 dev_err(&master->dev, "queue restart failed\n");
1004 EXPORT_SYMBOL_GPL(spi_master_resume);
1006 static int __spi_master_match(struct device *dev, void *data)
1008 struct spi_master *m;
1009 u16 *bus_num = data;
1011 m = container_of(dev, struct spi_master, dev);
1012 return m->bus_num == *bus_num;
1016 * spi_busnum_to_master - look up master associated with bus_num
1017 * @bus_num: the master's bus number
1018 * Context: can sleep
1020 * This call may be used with devices that are registered after
1021 * arch init time. It returns a refcounted pointer to the relevant
1022 * spi_master (which the caller must release), or NULL if there is
1023 * no such master registered.
1025 struct spi_master *spi_busnum_to_master(u16 bus_num)
1028 struct spi_master *master = NULL;
1030 dev = class_find_device(&spi_master_class, NULL, &bus_num,
1031 __spi_master_match);
1033 master = container_of(dev, struct spi_master, dev);
1034 /* reference got in class_find_device */
1037 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
1040 /*-------------------------------------------------------------------------*/
1042 /* Core methods for SPI master protocol drivers. Some of the
1043 * other core methods are currently defined as inline functions.
1047 * spi_setup - setup SPI mode and clock rate
1048 * @spi: the device whose settings are being modified
1049 * Context: can sleep, and no requests are queued to the device
1051 * SPI protocol drivers may need to update the transfer mode if the
1052 * device doesn't work with its default. They may likewise need
1053 * to update clock rates or word sizes from initial values. This function
1054 * changes those settings, and must be called from a context that can sleep.
1055 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
1056 * effect the next time the device is selected and data is transferred to
1057 * or from it. When this function returns, the spi device is deselected.
1059 * Note that this call will fail if the protocol driver specifies an option
1060 * that the underlying controller or its driver does not support. For
1061 * example, not all hardware supports wire transfers using nine bit words,
1062 * LSB-first wire encoding, or active-high chipselects.
1064 int spi_setup(struct spi_device *spi)
1069 /* help drivers fail *cleanly* when they need options
1070 * that aren't supported with their current master
1072 bad_bits = spi->mode & ~spi->master->mode_bits;
1074 dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
1079 if (!spi->bits_per_word)
1080 spi->bits_per_word = 8;
1082 status = spi->master->setup(spi);
1084 dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
1085 "%u bits/w, %u Hz max --> %d\n",
1086 (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
1087 (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
1088 (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
1089 (spi->mode & SPI_3WIRE) ? "3wire, " : "",
1090 (spi->mode & SPI_LOOP) ? "loopback, " : "",
1091 spi->bits_per_word, spi->max_speed_hz,
1096 EXPORT_SYMBOL_GPL(spi_setup);
1098 static int __spi_async(struct spi_device *spi, struct spi_message *message)
1100 struct spi_master *master = spi->master;
1102 /* Half-duplex links include original MicroWire, and ones with
1103 * only one data pin like SPI_3WIRE (switches direction) or where
1104 * either MOSI or MISO is missing. They can also be caused by
1105 * software limitations.
1107 if ((master->flags & SPI_MASTER_HALF_DUPLEX)
1108 || (spi->mode & SPI_3WIRE)) {
1109 struct spi_transfer *xfer;
1110 unsigned flags = master->flags;
1112 list_for_each_entry(xfer, &message->transfers, transfer_list) {
1113 if (xfer->rx_buf && xfer->tx_buf)
1115 if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
1117 if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
1123 message->status = -EINPROGRESS;
1124 return master->transfer(spi, message);
1128 * spi_async - asynchronous SPI transfer
1129 * @spi: device with which data will be exchanged
1130 * @message: describes the data transfers, including completion callback
1131 * Context: any (irqs may be blocked, etc)
1133 * This call may be used in_irq and other contexts which can't sleep,
1134 * as well as from task contexts which can sleep.
1136 * The completion callback is invoked in a context which can't sleep.
1137 * Before that invocation, the value of message->status is undefined.
1138 * When the callback is issued, message->status holds either zero (to
1139 * indicate complete success) or a negative error code. After that
1140 * callback returns, the driver which issued the transfer request may
1141 * deallocate the associated memory; it's no longer in use by any SPI
1142 * core or controller driver code.
1144 * Note that although all messages to a spi_device are handled in
1145 * FIFO order, messages may go to different devices in other orders.
1146 * Some device might be higher priority, or have various "hard" access
1147 * time requirements, for example.
1149 * On detection of any fault during the transfer, processing of
1150 * the entire message is aborted, and the device is deselected.
1151 * Until returning from the associated message completion callback,
1152 * no other spi_message queued to that device will be processed.
1153 * (This rule applies equally to all the synchronous transfer calls,
1154 * which are wrappers around this core asynchronous primitive.)
1156 int spi_async(struct spi_device *spi, struct spi_message *message)
1158 struct spi_master *master = spi->master;
1160 unsigned long flags;
1162 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1164 if (master->bus_lock_flag)
1167 ret = __spi_async(spi, message);
1169 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1173 EXPORT_SYMBOL_GPL(spi_async);
1176 * spi_async_locked - version of spi_async with exclusive bus usage
1177 * @spi: device with which data will be exchanged
1178 * @message: describes the data transfers, including completion callback
1179 * Context: any (irqs may be blocked, etc)
1181 * This call may be used in_irq and other contexts which can't sleep,
1182 * as well as from task contexts which can sleep.
1184 * The completion callback is invoked in a context which can't sleep.
1185 * Before that invocation, the value of message->status is undefined.
1186 * When the callback is issued, message->status holds either zero (to
1187 * indicate complete success) or a negative error code. After that
1188 * callback returns, the driver which issued the transfer request may
1189 * deallocate the associated memory; it's no longer in use by any SPI
1190 * core or controller driver code.
1192 * Note that although all messages to a spi_device are handled in
1193 * FIFO order, messages may go to different devices in other orders.
1194 * Some device might be higher priority, or have various "hard" access
1195 * time requirements, for example.
1197 * On detection of any fault during the transfer, processing of
1198 * the entire message is aborted, and the device is deselected.
1199 * Until returning from the associated message completion callback,
1200 * no other spi_message queued to that device will be processed.
1201 * (This rule applies equally to all the synchronous transfer calls,
1202 * which are wrappers around this core asynchronous primitive.)
1204 int spi_async_locked(struct spi_device *spi, struct spi_message *message)
1206 struct spi_master *master = spi->master;
1208 unsigned long flags;
1210 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1212 ret = __spi_async(spi, message);
1214 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1219 EXPORT_SYMBOL_GPL(spi_async_locked);
1222 /*-------------------------------------------------------------------------*/
1224 /* Utility methods for SPI master protocol drivers, layered on
1225 * top of the core. Some other utility methods are defined as
1229 static void spi_complete(void *arg)
1234 static int __spi_sync(struct spi_device *spi, struct spi_message *message,
1237 DECLARE_COMPLETION_ONSTACK(done);
1239 struct spi_master *master = spi->master;
1241 message->complete = spi_complete;
1242 message->context = &done;
1245 mutex_lock(&master->bus_lock_mutex);
1247 status = spi_async_locked(spi, message);
1250 mutex_unlock(&master->bus_lock_mutex);
1253 wait_for_completion(&done);
1254 status = message->status;
1256 message->context = NULL;
1261 * spi_sync - blocking/synchronous SPI data transfers
1262 * @spi: device with which data will be exchanged
1263 * @message: describes the data transfers
1264 * Context: can sleep
1266 * This call may only be used from a context that may sleep. The sleep
1267 * is non-interruptible, and has no timeout. Low-overhead controller
1268 * drivers may DMA directly into and out of the message buffers.
1270 * Note that the SPI device's chip select is active during the message,
1271 * and then is normally disabled between messages. Drivers for some
1272 * frequently-used devices may want to minimize costs of selecting a chip,
1273 * by leaving it selected in anticipation that the next message will go
1274 * to the same chip. (That may increase power usage.)
1276 * Also, the caller is guaranteeing that the memory associated with the
1277 * message will not be freed before this call returns.
1279 * It returns zero on success, else a negative error code.
1281 int spi_sync(struct spi_device *spi, struct spi_message *message)
1283 return __spi_sync(spi, message, 0);
1285 EXPORT_SYMBOL_GPL(spi_sync);
1288 * spi_sync_locked - version of spi_sync with exclusive bus usage
1289 * @spi: device with which data will be exchanged
1290 * @message: describes the data transfers
1291 * Context: can sleep
1293 * This call may only be used from a context that may sleep. The sleep
1294 * is non-interruptible, and has no timeout. Low-overhead controller
1295 * drivers may DMA directly into and out of the message buffers.
1297 * This call should be used by drivers that require exclusive access to the
1298 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
1299 * be released by a spi_bus_unlock call when the exclusive access is over.
1301 * It returns zero on success, else a negative error code.
1303 int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
1305 return __spi_sync(spi, message, 1);
1307 EXPORT_SYMBOL_GPL(spi_sync_locked);
1310 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
1311 * @master: SPI bus master that should be locked for exclusive bus access
1312 * Context: can sleep
1314 * This call may only be used from a context that may sleep. The sleep
1315 * is non-interruptible, and has no timeout.
1317 * This call should be used by drivers that require exclusive access to the
1318 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
1319 * exclusive access is over. Data transfer must be done by spi_sync_locked
1320 * and spi_async_locked calls when the SPI bus lock is held.
1322 * It returns zero on success, else a negative error code.
1324 int spi_bus_lock(struct spi_master *master)
1326 unsigned long flags;
1328 mutex_lock(&master->bus_lock_mutex);
1330 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1331 master->bus_lock_flag = 1;
1332 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1334 /* mutex remains locked until spi_bus_unlock is called */
1338 EXPORT_SYMBOL_GPL(spi_bus_lock);
1341 * spi_bus_unlock - release the lock for exclusive SPI bus usage
1342 * @master: SPI bus master that was locked for exclusive bus access
1343 * Context: can sleep
1345 * This call may only be used from a context that may sleep. The sleep
1346 * is non-interruptible, and has no timeout.
1348 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
1351 * It returns zero on success, else a negative error code.
1353 int spi_bus_unlock(struct spi_master *master)
1355 master->bus_lock_flag = 0;
1357 mutex_unlock(&master->bus_lock_mutex);
1361 EXPORT_SYMBOL_GPL(spi_bus_unlock);
1363 /* portable code must never pass more than 32 bytes */
1364 #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
1369 * spi_write_then_read - SPI synchronous write followed by read
1370 * @spi: device with which data will be exchanged
1371 * @txbuf: data to be written (need not be dma-safe)
1372 * @n_tx: size of txbuf, in bytes
1373 * @rxbuf: buffer into which data will be read (need not be dma-safe)
1374 * @n_rx: size of rxbuf, in bytes
1375 * Context: can sleep
1377 * This performs a half duplex MicroWire style transaction with the
1378 * device, sending txbuf and then reading rxbuf. The return value
1379 * is zero for success, else a negative errno status code.
1380 * This call may only be used from a context that may sleep.
1382 * Parameters to this routine are always copied using a small buffer;
1383 * portable code should never use this for more than 32 bytes.
1384 * Performance-sensitive or bulk transfer code should instead use
1385 * spi_{async,sync}() calls with dma-safe buffers.
1387 int spi_write_then_read(struct spi_device *spi,
1388 const void *txbuf, unsigned n_tx,
1389 void *rxbuf, unsigned n_rx)
1391 static DEFINE_MUTEX(lock);
1394 struct spi_message message;
1395 struct spi_transfer x[2];
1398 /* Use preallocated DMA-safe buffer. We can't avoid copying here,
1399 * (as a pure convenience thing), but we can keep heap costs
1400 * out of the hot path ...
1402 if ((n_tx + n_rx) > SPI_BUFSIZ)
1405 spi_message_init(&message);
1406 memset(x, 0, sizeof x);
1409 spi_message_add_tail(&x[0], &message);
1413 spi_message_add_tail(&x[1], &message);
1416 /* ... unless someone else is using the pre-allocated buffer */
1417 if (!mutex_trylock(&lock)) {
1418 local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1424 memcpy(local_buf, txbuf, n_tx);
1425 x[0].tx_buf = local_buf;
1426 x[1].rx_buf = local_buf + n_tx;
1429 status = spi_sync(spi, &message);
1431 memcpy(rxbuf, x[1].rx_buf, n_rx);
1433 if (x[0].tx_buf == buf)
1434 mutex_unlock(&lock);
1440 EXPORT_SYMBOL_GPL(spi_write_then_read);
1442 /*-------------------------------------------------------------------------*/
1444 static int __init spi_init(void)
1448 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1454 status = bus_register(&spi_bus_type);
1458 status = class_register(&spi_master_class);
1464 bus_unregister(&spi_bus_type);
1472 /* board_info is normally registered in arch_initcall(),
1473 * but even essential drivers wait till later
1475 * REVISIT only boardinfo really needs static linking. the rest (device and
1476 * driver registration) _could_ be dynamically linked (modular) ... costs
1477 * include needing to have boardinfo data structures be much more public.
1479 postcore_initcall(spi_init);