4 * Copyright (C) 2005 David Brownell
5 * Copyright (C) 2008 Secret Lab Technologies Ltd.
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 #include <linux/kernel.h>
23 #include <linux/kmod.h>
24 #include <linux/device.h>
25 #include <linux/init.h>
26 #include <linux/cache.h>
27 #include <linux/mutex.h>
28 #include <linux/of_device.h>
29 #include <linux/of_irq.h>
30 #include <linux/slab.h>
31 #include <linux/mod_devicetable.h>
32 #include <linux/spi/spi.h>
33 #include <linux/of_gpio.h>
34 #include <linux/pm_runtime.h>
35 #include <linux/export.h>
36 #include <linux/sched/rt.h>
37 #include <linux/delay.h>
38 #include <linux/kthread.h>
39 #include <linux/ioport.h>
40 #include <linux/acpi.h>
42 static void spidev_release(struct device *dev)
44 struct spi_device *spi = to_spi_device(dev);
46 /* spi masters may cleanup for released devices */
47 if (spi->master->cleanup)
48 spi->master->cleanup(spi);
50 spi_master_put(spi->master);
55 modalias_show(struct device *dev, struct device_attribute *a, char *buf)
57 const struct spi_device *spi = to_spi_device(dev);
59 return sprintf(buf, "%s%s\n", SPI_MODULE_PREFIX, spi->modalias);
61 static DEVICE_ATTR_RO(modalias);
63 static struct attribute *spi_dev_attrs[] = {
64 &dev_attr_modalias.attr,
67 ATTRIBUTE_GROUPS(spi_dev);
69 /* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
70 * and the sysfs version makes coldplug work too.
73 static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
74 const struct spi_device *sdev)
77 if (!strcmp(sdev->modalias, id->name))
84 const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
86 const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
88 return spi_match_id(sdrv->id_table, sdev);
90 EXPORT_SYMBOL_GPL(spi_get_device_id);
92 static int spi_match_device(struct device *dev, struct device_driver *drv)
94 const struct spi_device *spi = to_spi_device(dev);
95 const struct spi_driver *sdrv = to_spi_driver(drv);
97 /* Attempt an OF style match */
98 if (of_driver_match_device(dev, drv))
102 if (acpi_driver_match_device(dev, drv))
106 return !!spi_match_id(sdrv->id_table, spi);
108 return strcmp(spi->modalias, drv->name) == 0;
111 static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
113 const struct spi_device *spi = to_spi_device(dev);
115 add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
119 #ifdef CONFIG_PM_SLEEP
120 static int spi_legacy_suspend(struct device *dev, pm_message_t message)
123 struct spi_driver *drv = to_spi_driver(dev->driver);
125 /* suspend will stop irqs and dma; no more i/o */
128 value = drv->suspend(to_spi_device(dev), message);
130 dev_dbg(dev, "... can't suspend\n");
135 static int spi_legacy_resume(struct device *dev)
138 struct spi_driver *drv = to_spi_driver(dev->driver);
140 /* resume may restart the i/o queue */
143 value = drv->resume(to_spi_device(dev));
145 dev_dbg(dev, "... can't resume\n");
150 static int spi_pm_suspend(struct device *dev)
152 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
155 return pm_generic_suspend(dev);
157 return spi_legacy_suspend(dev, PMSG_SUSPEND);
160 static int spi_pm_resume(struct device *dev)
162 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
165 return pm_generic_resume(dev);
167 return spi_legacy_resume(dev);
170 static int spi_pm_freeze(struct device *dev)
172 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
175 return pm_generic_freeze(dev);
177 return spi_legacy_suspend(dev, PMSG_FREEZE);
180 static int spi_pm_thaw(struct device *dev)
182 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
185 return pm_generic_thaw(dev);
187 return spi_legacy_resume(dev);
190 static int spi_pm_poweroff(struct device *dev)
192 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
195 return pm_generic_poweroff(dev);
197 return spi_legacy_suspend(dev, PMSG_HIBERNATE);
200 static int spi_pm_restore(struct device *dev)
202 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
205 return pm_generic_restore(dev);
207 return spi_legacy_resume(dev);
210 #define spi_pm_suspend NULL
211 #define spi_pm_resume NULL
212 #define spi_pm_freeze NULL
213 #define spi_pm_thaw NULL
214 #define spi_pm_poweroff NULL
215 #define spi_pm_restore NULL
218 static const struct dev_pm_ops spi_pm = {
219 .suspend = spi_pm_suspend,
220 .resume = spi_pm_resume,
221 .freeze = spi_pm_freeze,
223 .poweroff = spi_pm_poweroff,
224 .restore = spi_pm_restore,
226 pm_generic_runtime_suspend,
227 pm_generic_runtime_resume,
232 struct bus_type spi_bus_type = {
234 .dev_groups = spi_dev_groups,
235 .match = spi_match_device,
236 .uevent = spi_uevent,
239 EXPORT_SYMBOL_GPL(spi_bus_type);
242 static int spi_drv_probe(struct device *dev)
244 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
246 return sdrv->probe(to_spi_device(dev));
249 static int spi_drv_remove(struct device *dev)
251 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
253 return sdrv->remove(to_spi_device(dev));
256 static void spi_drv_shutdown(struct device *dev)
258 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
260 sdrv->shutdown(to_spi_device(dev));
264 * spi_register_driver - register a SPI driver
265 * @sdrv: the driver to register
268 int spi_register_driver(struct spi_driver *sdrv)
270 sdrv->driver.bus = &spi_bus_type;
272 sdrv->driver.probe = spi_drv_probe;
274 sdrv->driver.remove = spi_drv_remove;
276 sdrv->driver.shutdown = spi_drv_shutdown;
277 return driver_register(&sdrv->driver);
279 EXPORT_SYMBOL_GPL(spi_register_driver);
281 /*-------------------------------------------------------------------------*/
283 /* SPI devices should normally not be created by SPI device drivers; that
284 * would make them board-specific. Similarly with SPI master drivers.
285 * Device registration normally goes into like arch/.../mach.../board-YYY.c
286 * with other readonly (flashable) information about mainboard devices.
290 struct list_head list;
291 struct spi_board_info board_info;
294 static LIST_HEAD(board_list);
295 static LIST_HEAD(spi_master_list);
298 * Used to protect add/del opertion for board_info list and
299 * spi_master list, and their matching process
301 static DEFINE_MUTEX(board_lock);
304 * spi_alloc_device - Allocate a new SPI device
305 * @master: Controller to which device is connected
308 * Allows a driver to allocate and initialize a spi_device without
309 * registering it immediately. This allows a driver to directly
310 * fill the spi_device with device parameters before calling
311 * spi_add_device() on it.
313 * Caller is responsible to call spi_add_device() on the returned
314 * spi_device structure to add it to the SPI master. If the caller
315 * needs to discard the spi_device without adding it, then it should
316 * call spi_dev_put() on it.
318 * Returns a pointer to the new device, or NULL.
320 struct spi_device *spi_alloc_device(struct spi_master *master)
322 struct spi_device *spi;
323 struct device *dev = master->dev.parent;
325 if (!spi_master_get(master))
328 spi = kzalloc(sizeof(*spi), GFP_KERNEL);
330 dev_err(dev, "cannot alloc spi_device\n");
331 spi_master_put(master);
335 spi->master = master;
336 spi->dev.parent = &master->dev;
337 spi->dev.bus = &spi_bus_type;
338 spi->dev.release = spidev_release;
339 spi->cs_gpio = -ENOENT;
340 device_initialize(&spi->dev);
343 EXPORT_SYMBOL_GPL(spi_alloc_device);
346 * spi_add_device - Add spi_device allocated with spi_alloc_device
347 * @spi: spi_device to register
349 * Companion function to spi_alloc_device. Devices allocated with
350 * spi_alloc_device can be added onto the spi bus with this function.
352 * Returns 0 on success; negative errno on failure
354 int spi_add_device(struct spi_device *spi)
356 static DEFINE_MUTEX(spi_add_lock);
357 struct spi_master *master = spi->master;
358 struct device *dev = master->dev.parent;
362 /* Chipselects are numbered 0..max; validate. */
363 if (spi->chip_select >= master->num_chipselect) {
364 dev_err(dev, "cs%d >= max %d\n",
366 master->num_chipselect);
370 /* Set the bus ID string */
371 dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
375 /* We need to make sure there's no other device with this
376 * chipselect **BEFORE** we call setup(), else we'll trash
377 * its configuration. Lock against concurrent add() calls.
379 mutex_lock(&spi_add_lock);
381 d = bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));
383 dev_err(dev, "chipselect %d already in use\n",
390 if (master->cs_gpios)
391 spi->cs_gpio = master->cs_gpios[spi->chip_select];
393 /* Drivers may modify this initial i/o setup, but will
394 * normally rely on the device being setup. Devices
395 * using SPI_CS_HIGH can't coexist well otherwise...
397 status = spi_setup(spi);
399 dev_err(dev, "can't setup %s, status %d\n",
400 dev_name(&spi->dev), status);
404 /* Device may be bound to an active driver when this returns */
405 status = device_add(&spi->dev);
407 dev_err(dev, "can't add %s, status %d\n",
408 dev_name(&spi->dev), status);
410 dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
413 mutex_unlock(&spi_add_lock);
416 EXPORT_SYMBOL_GPL(spi_add_device);
419 * spi_new_device - instantiate one new SPI device
420 * @master: Controller to which device is connected
421 * @chip: Describes the SPI device
424 * On typical mainboards, this is purely internal; and it's not needed
425 * after board init creates the hard-wired devices. Some development
426 * platforms may not be able to use spi_register_board_info though, and
427 * this is exported so that for example a USB or parport based adapter
428 * driver could add devices (which it would learn about out-of-band).
430 * Returns the new device, or NULL.
432 struct spi_device *spi_new_device(struct spi_master *master,
433 struct spi_board_info *chip)
435 struct spi_device *proxy;
438 /* NOTE: caller did any chip->bus_num checks necessary.
440 * Also, unless we change the return value convention to use
441 * error-or-pointer (not NULL-or-pointer), troubleshootability
442 * suggests syslogged diagnostics are best here (ugh).
445 proxy = spi_alloc_device(master);
449 WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
451 proxy->chip_select = chip->chip_select;
452 proxy->max_speed_hz = chip->max_speed_hz;
453 proxy->mode = chip->mode;
454 proxy->irq = chip->irq;
455 strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
456 proxy->dev.platform_data = (void *) chip->platform_data;
457 proxy->controller_data = chip->controller_data;
458 proxy->controller_state = NULL;
460 status = spi_add_device(proxy);
468 EXPORT_SYMBOL_GPL(spi_new_device);
470 static void spi_match_master_to_boardinfo(struct spi_master *master,
471 struct spi_board_info *bi)
473 struct spi_device *dev;
475 if (master->bus_num != bi->bus_num)
478 dev = spi_new_device(master, bi);
480 dev_err(master->dev.parent, "can't create new device for %s\n",
485 * spi_register_board_info - register SPI devices for a given board
486 * @info: array of chip descriptors
487 * @n: how many descriptors are provided
490 * Board-specific early init code calls this (probably during arch_initcall)
491 * with segments of the SPI device table. Any device nodes are created later,
492 * after the relevant parent SPI controller (bus_num) is defined. We keep
493 * this table of devices forever, so that reloading a controller driver will
494 * not make Linux forget about these hard-wired devices.
496 * Other code can also call this, e.g. a particular add-on board might provide
497 * SPI devices through its expansion connector, so code initializing that board
498 * would naturally declare its SPI devices.
500 * The board info passed can safely be __initdata ... but be careful of
501 * any embedded pointers (platform_data, etc), they're copied as-is.
503 int spi_register_board_info(struct spi_board_info const *info, unsigned n)
505 struct boardinfo *bi;
508 bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
512 for (i = 0; i < n; i++, bi++, info++) {
513 struct spi_master *master;
515 memcpy(&bi->board_info, info, sizeof(*info));
516 mutex_lock(&board_lock);
517 list_add_tail(&bi->list, &board_list);
518 list_for_each_entry(master, &spi_master_list, list)
519 spi_match_master_to_boardinfo(master, &bi->board_info);
520 mutex_unlock(&board_lock);
526 /*-------------------------------------------------------------------------*/
529 * spi_pump_messages - kthread work function which processes spi message queue
530 * @work: pointer to kthread work struct contained in the master struct
532 * This function checks if there is any spi message in the queue that
533 * needs processing and if so call out to the driver to initialize hardware
534 * and transfer each message.
537 static void spi_pump_messages(struct kthread_work *work)
539 struct spi_master *master =
540 container_of(work, struct spi_master, pump_messages);
542 bool was_busy = false;
545 /* Lock queue and check for queue work */
546 spin_lock_irqsave(&master->queue_lock, flags);
547 if (list_empty(&master->queue) || !master->running) {
549 spin_unlock_irqrestore(&master->queue_lock, flags);
552 master->busy = false;
553 spin_unlock_irqrestore(&master->queue_lock, flags);
554 if (master->unprepare_transfer_hardware &&
555 master->unprepare_transfer_hardware(master))
556 dev_err(&master->dev,
557 "failed to unprepare transfer hardware\n");
558 if (master->auto_runtime_pm) {
559 pm_runtime_mark_last_busy(master->dev.parent);
560 pm_runtime_put_autosuspend(master->dev.parent);
565 /* Make sure we are not already running a message */
566 if (master->cur_msg) {
567 spin_unlock_irqrestore(&master->queue_lock, flags);
570 /* Extract head of queue */
572 list_entry(master->queue.next, struct spi_message, queue);
574 list_del_init(&master->cur_msg->queue);
579 spin_unlock_irqrestore(&master->queue_lock, flags);
581 if (!was_busy && master->auto_runtime_pm) {
582 ret = pm_runtime_get_sync(master->dev.parent);
584 dev_err(&master->dev, "Failed to power device: %d\n",
590 if (!was_busy && master->prepare_transfer_hardware) {
591 ret = master->prepare_transfer_hardware(master);
593 dev_err(&master->dev,
594 "failed to prepare transfer hardware\n");
596 if (master->auto_runtime_pm)
597 pm_runtime_put(master->dev.parent);
602 ret = master->transfer_one_message(master, master->cur_msg);
604 dev_err(&master->dev,
605 "failed to transfer one message from queue\n");
610 static int spi_init_queue(struct spi_master *master)
612 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
614 INIT_LIST_HEAD(&master->queue);
615 spin_lock_init(&master->queue_lock);
617 master->running = false;
618 master->busy = false;
620 init_kthread_worker(&master->kworker);
621 master->kworker_task = kthread_run(kthread_worker_fn,
622 &master->kworker, "%s",
623 dev_name(&master->dev));
624 if (IS_ERR(master->kworker_task)) {
625 dev_err(&master->dev, "failed to create message pump task\n");
628 init_kthread_work(&master->pump_messages, spi_pump_messages);
631 * Master config will indicate if this controller should run the
632 * message pump with high (realtime) priority to reduce the transfer
633 * latency on the bus by minimising the delay between a transfer
634 * request and the scheduling of the message pump thread. Without this
635 * setting the message pump thread will remain at default priority.
638 dev_info(&master->dev,
639 "will run message pump with realtime priority\n");
640 sched_setscheduler(master->kworker_task, SCHED_FIFO, ¶m);
647 * spi_get_next_queued_message() - called by driver to check for queued
649 * @master: the master to check for queued messages
651 * If there are more messages in the queue, the next message is returned from
654 struct spi_message *spi_get_next_queued_message(struct spi_master *master)
656 struct spi_message *next;
659 /* get a pointer to the next message, if any */
660 spin_lock_irqsave(&master->queue_lock, flags);
661 if (list_empty(&master->queue))
664 next = list_entry(master->queue.next,
665 struct spi_message, queue);
666 spin_unlock_irqrestore(&master->queue_lock, flags);
670 EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
673 * spi_finalize_current_message() - the current message is complete
674 * @master: the master to return the message to
676 * Called by the driver to notify the core that the message in the front of the
677 * queue is complete and can be removed from the queue.
679 void spi_finalize_current_message(struct spi_master *master)
681 struct spi_message *mesg;
684 spin_lock_irqsave(&master->queue_lock, flags);
685 mesg = master->cur_msg;
686 master->cur_msg = NULL;
688 queue_kthread_work(&master->kworker, &master->pump_messages);
689 spin_unlock_irqrestore(&master->queue_lock, flags);
693 mesg->complete(mesg->context);
695 EXPORT_SYMBOL_GPL(spi_finalize_current_message);
697 static int spi_start_queue(struct spi_master *master)
701 spin_lock_irqsave(&master->queue_lock, flags);
703 if (master->running || master->busy) {
704 spin_unlock_irqrestore(&master->queue_lock, flags);
708 master->running = true;
709 master->cur_msg = NULL;
710 spin_unlock_irqrestore(&master->queue_lock, flags);
712 queue_kthread_work(&master->kworker, &master->pump_messages);
717 static int spi_stop_queue(struct spi_master *master)
720 unsigned limit = 500;
723 spin_lock_irqsave(&master->queue_lock, flags);
726 * This is a bit lame, but is optimized for the common execution path.
727 * A wait_queue on the master->busy could be used, but then the common
728 * execution path (pump_messages) would be required to call wake_up or
729 * friends on every SPI message. Do this instead.
731 while ((!list_empty(&master->queue) || master->busy) && limit--) {
732 spin_unlock_irqrestore(&master->queue_lock, flags);
734 spin_lock_irqsave(&master->queue_lock, flags);
737 if (!list_empty(&master->queue) || master->busy)
740 master->running = false;
742 spin_unlock_irqrestore(&master->queue_lock, flags);
745 dev_warn(&master->dev,
746 "could not stop message queue\n");
752 static int spi_destroy_queue(struct spi_master *master)
756 ret = spi_stop_queue(master);
759 * flush_kthread_worker will block until all work is done.
760 * If the reason that stop_queue timed out is that the work will never
761 * finish, then it does no good to call flush/stop thread, so
765 dev_err(&master->dev, "problem destroying queue\n");
769 flush_kthread_worker(&master->kworker);
770 kthread_stop(master->kworker_task);
776 * spi_queued_transfer - transfer function for queued transfers
777 * @spi: spi device which is requesting transfer
778 * @msg: spi message which is to handled is queued to driver queue
780 static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
782 struct spi_master *master = spi->master;
785 spin_lock_irqsave(&master->queue_lock, flags);
787 if (!master->running) {
788 spin_unlock_irqrestore(&master->queue_lock, flags);
791 msg->actual_length = 0;
792 msg->status = -EINPROGRESS;
794 list_add_tail(&msg->queue, &master->queue);
796 queue_kthread_work(&master->kworker, &master->pump_messages);
798 spin_unlock_irqrestore(&master->queue_lock, flags);
802 static int spi_master_initialize_queue(struct spi_master *master)
806 master->queued = true;
807 master->transfer = spi_queued_transfer;
809 /* Initialize and start queue */
810 ret = spi_init_queue(master);
812 dev_err(&master->dev, "problem initializing queue\n");
815 ret = spi_start_queue(master);
817 dev_err(&master->dev, "problem starting queue\n");
818 goto err_start_queue;
825 spi_destroy_queue(master);
829 /*-------------------------------------------------------------------------*/
831 #if defined(CONFIG_OF)
833 * of_register_spi_devices() - Register child devices onto the SPI bus
834 * @master: Pointer to spi_master device
836 * Registers an spi_device for each child node of master node which has a 'reg'
839 static void of_register_spi_devices(struct spi_master *master)
841 struct spi_device *spi;
842 struct device_node *nc;
846 if (!master->dev.of_node)
849 for_each_available_child_of_node(master->dev.of_node, nc) {
850 /* Alloc an spi_device */
851 spi = spi_alloc_device(master);
853 dev_err(&master->dev, "spi_device alloc error for %s\n",
859 /* Select device driver */
860 if (of_modalias_node(nc, spi->modalias,
861 sizeof(spi->modalias)) < 0) {
862 dev_err(&master->dev, "cannot find modalias for %s\n",
869 rc = of_property_read_u32(nc, "reg", &value);
871 dev_err(&master->dev, "%s has no valid 'reg' property (%d)\n",
876 spi->chip_select = value;
878 /* Mode (clock phase/polarity/etc.) */
879 if (of_find_property(nc, "spi-cpha", NULL))
880 spi->mode |= SPI_CPHA;
881 if (of_find_property(nc, "spi-cpol", NULL))
882 spi->mode |= SPI_CPOL;
883 if (of_find_property(nc, "spi-cs-high", NULL))
884 spi->mode |= SPI_CS_HIGH;
885 if (of_find_property(nc, "spi-3wire", NULL))
886 spi->mode |= SPI_3WIRE;
888 /* Device DUAL/QUAD mode */
889 if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
894 spi->mode |= SPI_TX_DUAL;
897 spi->mode |= SPI_TX_QUAD;
900 dev_err(&master->dev,
901 "spi-tx-bus-width %d not supported\n",
908 if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
913 spi->mode |= SPI_RX_DUAL;
916 spi->mode |= SPI_RX_QUAD;
919 dev_err(&master->dev,
920 "spi-rx-bus-width %d not supported\n",
928 rc = of_property_read_u32(nc, "spi-max-frequency", &value);
930 dev_err(&master->dev, "%s has no valid 'spi-max-frequency' property (%d)\n",
935 spi->max_speed_hz = value;
938 spi->irq = irq_of_parse_and_map(nc, 0);
940 /* Store a pointer to the node in the device structure */
942 spi->dev.of_node = nc;
944 /* Register the new device */
945 request_module("%s%s", SPI_MODULE_PREFIX, spi->modalias);
946 rc = spi_add_device(spi);
948 dev_err(&master->dev, "spi_device register error %s\n",
956 static void of_register_spi_devices(struct spi_master *master) { }
960 static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
962 struct spi_device *spi = data;
964 if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
965 struct acpi_resource_spi_serialbus *sb;
967 sb = &ares->data.spi_serial_bus;
968 if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
969 spi->chip_select = sb->device_selection;
970 spi->max_speed_hz = sb->connection_speed;
972 if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
973 spi->mode |= SPI_CPHA;
974 if (sb->clock_polarity == ACPI_SPI_START_HIGH)
975 spi->mode |= SPI_CPOL;
976 if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
977 spi->mode |= SPI_CS_HIGH;
979 } else if (spi->irq < 0) {
982 if (acpi_dev_resource_interrupt(ares, 0, &r))
986 /* Always tell the ACPI core to skip this resource */
990 static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
991 void *data, void **return_value)
993 struct spi_master *master = data;
994 struct list_head resource_list;
995 struct acpi_device *adev;
996 struct spi_device *spi;
999 if (acpi_bus_get_device(handle, &adev))
1001 if (acpi_bus_get_status(adev) || !adev->status.present)
1004 spi = spi_alloc_device(master);
1006 dev_err(&master->dev, "failed to allocate SPI device for %s\n",
1007 dev_name(&adev->dev));
1008 return AE_NO_MEMORY;
1011 ACPI_HANDLE_SET(&spi->dev, handle);
1014 INIT_LIST_HEAD(&resource_list);
1015 ret = acpi_dev_get_resources(adev, &resource_list,
1016 acpi_spi_add_resource, spi);
1017 acpi_dev_free_resource_list(&resource_list);
1019 if (ret < 0 || !spi->max_speed_hz) {
1024 strlcpy(spi->modalias, dev_name(&adev->dev), sizeof(spi->modalias));
1025 if (spi_add_device(spi)) {
1026 dev_err(&master->dev, "failed to add SPI device %s from ACPI\n",
1027 dev_name(&adev->dev));
1034 static void acpi_register_spi_devices(struct spi_master *master)
1039 handle = ACPI_HANDLE(master->dev.parent);
1043 status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
1044 acpi_spi_add_device, NULL,
1046 if (ACPI_FAILURE(status))
1047 dev_warn(&master->dev, "failed to enumerate SPI slaves\n");
1050 static inline void acpi_register_spi_devices(struct spi_master *master) {}
1051 #endif /* CONFIG_ACPI */
1053 static void spi_master_release(struct device *dev)
1055 struct spi_master *master;
1057 master = container_of(dev, struct spi_master, dev);
1061 static struct class spi_master_class = {
1062 .name = "spi_master",
1063 .owner = THIS_MODULE,
1064 .dev_release = spi_master_release,
1070 * spi_alloc_master - allocate SPI master controller
1071 * @dev: the controller, possibly using the platform_bus
1072 * @size: how much zeroed driver-private data to allocate; the pointer to this
1073 * memory is in the driver_data field of the returned device,
1074 * accessible with spi_master_get_devdata().
1075 * Context: can sleep
1077 * This call is used only by SPI master controller drivers, which are the
1078 * only ones directly touching chip registers. It's how they allocate
1079 * an spi_master structure, prior to calling spi_register_master().
1081 * This must be called from context that can sleep. It returns the SPI
1082 * master structure on success, else NULL.
1084 * The caller is responsible for assigning the bus number and initializing
1085 * the master's methods before calling spi_register_master(); and (after errors
1086 * adding the device) calling spi_master_put() and kfree() to prevent a memory
1089 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
1091 struct spi_master *master;
1096 master = kzalloc(size + sizeof(*master), GFP_KERNEL);
1100 device_initialize(&master->dev);
1101 master->bus_num = -1;
1102 master->num_chipselect = 1;
1103 master->dev.class = &spi_master_class;
1104 master->dev.parent = get_device(dev);
1105 spi_master_set_devdata(master, &master[1]);
1109 EXPORT_SYMBOL_GPL(spi_alloc_master);
1112 static int of_spi_register_master(struct spi_master *master)
1115 struct device_node *np = master->dev.of_node;
1120 nb = of_gpio_named_count(np, "cs-gpios");
1121 master->num_chipselect = max_t(int, nb, master->num_chipselect);
1123 /* Return error only for an incorrectly formed cs-gpios property */
1124 if (nb == 0 || nb == -ENOENT)
1129 cs = devm_kzalloc(&master->dev,
1130 sizeof(int) * master->num_chipselect,
1132 master->cs_gpios = cs;
1134 if (!master->cs_gpios)
1137 for (i = 0; i < master->num_chipselect; i++)
1140 for (i = 0; i < nb; i++)
1141 cs[i] = of_get_named_gpio(np, "cs-gpios", i);
1146 static int of_spi_register_master(struct spi_master *master)
1153 * spi_register_master - register SPI master controller
1154 * @master: initialized master, originally from spi_alloc_master()
1155 * Context: can sleep
1157 * SPI master controllers connect to their drivers using some non-SPI bus,
1158 * such as the platform bus. The final stage of probe() in that code
1159 * includes calling spi_register_master() to hook up to this SPI bus glue.
1161 * SPI controllers use board specific (often SOC specific) bus numbers,
1162 * and board-specific addressing for SPI devices combines those numbers
1163 * with chip select numbers. Since SPI does not directly support dynamic
1164 * device identification, boards need configuration tables telling which
1165 * chip is at which address.
1167 * This must be called from context that can sleep. It returns zero on
1168 * success, else a negative error code (dropping the master's refcount).
1169 * After a successful return, the caller is responsible for calling
1170 * spi_unregister_master().
1172 int spi_register_master(struct spi_master *master)
1174 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
1175 struct device *dev = master->dev.parent;
1176 struct boardinfo *bi;
1177 int status = -ENODEV;
1183 status = of_spi_register_master(master);
1187 /* even if it's just one always-selected device, there must
1188 * be at least one chipselect
1190 if (master->num_chipselect == 0)
1193 if ((master->bus_num < 0) && master->dev.of_node)
1194 master->bus_num = of_alias_get_id(master->dev.of_node, "spi");
1196 /* convention: dynamically assigned bus IDs count down from the max */
1197 if (master->bus_num < 0) {
1198 /* FIXME switch to an IDR based scheme, something like
1199 * I2C now uses, so we can't run out of "dynamic" IDs
1201 master->bus_num = atomic_dec_return(&dyn_bus_id);
1205 spin_lock_init(&master->bus_lock_spinlock);
1206 mutex_init(&master->bus_lock_mutex);
1207 master->bus_lock_flag = 0;
1209 /* register the device, then userspace will see it.
1210 * registration fails if the bus ID is in use.
1212 dev_set_name(&master->dev, "spi%u", master->bus_num);
1213 status = device_add(&master->dev);
1216 dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
1217 dynamic ? " (dynamic)" : "");
1219 /* If we're using a queued driver, start the queue */
1220 if (master->transfer)
1221 dev_info(dev, "master is unqueued, this is deprecated\n");
1223 status = spi_master_initialize_queue(master);
1225 device_del(&master->dev);
1230 mutex_lock(&board_lock);
1231 list_add_tail(&master->list, &spi_master_list);
1232 list_for_each_entry(bi, &board_list, list)
1233 spi_match_master_to_boardinfo(master, &bi->board_info);
1234 mutex_unlock(&board_lock);
1236 /* Register devices from the device tree and ACPI */
1237 of_register_spi_devices(master);
1238 acpi_register_spi_devices(master);
1242 EXPORT_SYMBOL_GPL(spi_register_master);
1244 static int __unregister(struct device *dev, void *null)
1246 spi_unregister_device(to_spi_device(dev));
1251 * spi_unregister_master - unregister SPI master controller
1252 * @master: the master being unregistered
1253 * Context: can sleep
1255 * This call is used only by SPI master controller drivers, which are the
1256 * only ones directly touching chip registers.
1258 * This must be called from context that can sleep.
1260 void spi_unregister_master(struct spi_master *master)
1264 if (master->queued) {
1265 if (spi_destroy_queue(master))
1266 dev_err(&master->dev, "queue remove failed\n");
1269 mutex_lock(&board_lock);
1270 list_del(&master->list);
1271 mutex_unlock(&board_lock);
1273 dummy = device_for_each_child(&master->dev, NULL, __unregister);
1274 device_unregister(&master->dev);
1276 EXPORT_SYMBOL_GPL(spi_unregister_master);
1278 int spi_master_suspend(struct spi_master *master)
1282 /* Basically no-ops for non-queued masters */
1283 if (!master->queued)
1286 ret = spi_stop_queue(master);
1288 dev_err(&master->dev, "queue stop failed\n");
1292 EXPORT_SYMBOL_GPL(spi_master_suspend);
1294 int spi_master_resume(struct spi_master *master)
1298 if (!master->queued)
1301 ret = spi_start_queue(master);
1303 dev_err(&master->dev, "queue restart failed\n");
1307 EXPORT_SYMBOL_GPL(spi_master_resume);
1309 static int __spi_master_match(struct device *dev, const void *data)
1311 struct spi_master *m;
1312 const u16 *bus_num = data;
1314 m = container_of(dev, struct spi_master, dev);
1315 return m->bus_num == *bus_num;
1319 * spi_busnum_to_master - look up master associated with bus_num
1320 * @bus_num: the master's bus number
1321 * Context: can sleep
1323 * This call may be used with devices that are registered after
1324 * arch init time. It returns a refcounted pointer to the relevant
1325 * spi_master (which the caller must release), or NULL if there is
1326 * no such master registered.
1328 struct spi_master *spi_busnum_to_master(u16 bus_num)
1331 struct spi_master *master = NULL;
1333 dev = class_find_device(&spi_master_class, NULL, &bus_num,
1334 __spi_master_match);
1336 master = container_of(dev, struct spi_master, dev);
1337 /* reference got in class_find_device */
1340 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
1343 /*-------------------------------------------------------------------------*/
1345 /* Core methods for SPI master protocol drivers. Some of the
1346 * other core methods are currently defined as inline functions.
1350 * spi_setup - setup SPI mode and clock rate
1351 * @spi: the device whose settings are being modified
1352 * Context: can sleep, and no requests are queued to the device
1354 * SPI protocol drivers may need to update the transfer mode if the
1355 * device doesn't work with its default. They may likewise need
1356 * to update clock rates or word sizes from initial values. This function
1357 * changes those settings, and must be called from a context that can sleep.
1358 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
1359 * effect the next time the device is selected and data is transferred to
1360 * or from it. When this function returns, the spi device is deselected.
1362 * Note that this call will fail if the protocol driver specifies an option
1363 * that the underlying controller or its driver does not support. For
1364 * example, not all hardware supports wire transfers using nine bit words,
1365 * LSB-first wire encoding, or active-high chipselects.
1367 int spi_setup(struct spi_device *spi)
1372 /* check mode to prevent that DUAL and QUAD set at the same time
1374 if (((spi->mode & SPI_TX_DUAL) && (spi->mode & SPI_TX_QUAD)) ||
1375 ((spi->mode & SPI_RX_DUAL) && (spi->mode & SPI_RX_QUAD))) {
1377 "setup: can not select dual and quad at the same time\n");
1380 /* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
1382 if ((spi->mode & SPI_3WIRE) && (spi->mode &
1383 (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)))
1385 /* help drivers fail *cleanly* when they need options
1386 * that aren't supported with their current master
1388 bad_bits = spi->mode & ~spi->master->mode_bits;
1390 dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
1395 if (!spi->bits_per_word)
1396 spi->bits_per_word = 8;
1398 if (spi->master->setup)
1399 status = spi->master->setup(spi);
1401 dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s%u bits/w, %u Hz max --> %d\n",
1402 (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
1403 (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
1404 (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
1405 (spi->mode & SPI_3WIRE) ? "3wire, " : "",
1406 (spi->mode & SPI_LOOP) ? "loopback, " : "",
1407 spi->bits_per_word, spi->max_speed_hz,
1412 EXPORT_SYMBOL_GPL(spi_setup);
1414 static int __spi_async(struct spi_device *spi, struct spi_message *message)
1416 struct spi_master *master = spi->master;
1417 struct spi_transfer *xfer;
1419 if (list_empty(&message->transfers))
1421 if (!message->complete)
1424 /* Half-duplex links include original MicroWire, and ones with
1425 * only one data pin like SPI_3WIRE (switches direction) or where
1426 * either MOSI or MISO is missing. They can also be caused by
1427 * software limitations.
1429 if ((master->flags & SPI_MASTER_HALF_DUPLEX)
1430 || (spi->mode & SPI_3WIRE)) {
1431 unsigned flags = master->flags;
1433 list_for_each_entry(xfer, &message->transfers, transfer_list) {
1434 if (xfer->rx_buf && xfer->tx_buf)
1436 if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
1438 if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
1444 * Set transfer bits_per_word and max speed as spi device default if
1445 * it is not set for this transfer.
1446 * Set transfer tx_nbits and rx_nbits as single transfer default
1447 * (SPI_NBITS_SINGLE) if it is not set for this transfer.
1449 list_for_each_entry(xfer, &message->transfers, transfer_list) {
1450 message->frame_length += xfer->len;
1451 if (!xfer->bits_per_word)
1452 xfer->bits_per_word = spi->bits_per_word;
1453 if (!xfer->speed_hz) {
1454 xfer->speed_hz = spi->max_speed_hz;
1455 if (master->max_speed_hz &&
1456 xfer->speed_hz > master->max_speed_hz)
1457 xfer->speed_hz = master->max_speed_hz;
1460 if (master->bits_per_word_mask) {
1461 /* Only 32 bits fit in the mask */
1462 if (xfer->bits_per_word > 32)
1464 if (!(master->bits_per_word_mask &
1465 BIT(xfer->bits_per_word - 1)))
1469 if (xfer->speed_hz && master->min_speed_hz &&
1470 xfer->speed_hz < master->min_speed_hz)
1472 if (xfer->speed_hz && master->max_speed_hz &&
1473 xfer->speed_hz > master->max_speed_hz)
1476 if (xfer->tx_buf && !xfer->tx_nbits)
1477 xfer->tx_nbits = SPI_NBITS_SINGLE;
1478 if (xfer->rx_buf && !xfer->rx_nbits)
1479 xfer->rx_nbits = SPI_NBITS_SINGLE;
1480 /* check transfer tx/rx_nbits:
1481 * 1. keep the value is not out of single, dual and quad
1482 * 2. keep tx/rx_nbits is contained by mode in spi_device
1483 * 3. if SPI_3WIRE, tx/rx_nbits should be in single
1486 if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
1487 xfer->tx_nbits != SPI_NBITS_DUAL &&
1488 xfer->tx_nbits != SPI_NBITS_QUAD)
1490 if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
1491 !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
1493 if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
1494 !(spi->mode & SPI_TX_QUAD))
1496 if ((spi->mode & SPI_3WIRE) &&
1497 (xfer->tx_nbits != SPI_NBITS_SINGLE))
1500 /* check transfer rx_nbits */
1502 if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
1503 xfer->rx_nbits != SPI_NBITS_DUAL &&
1504 xfer->rx_nbits != SPI_NBITS_QUAD)
1506 if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
1507 !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
1509 if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
1510 !(spi->mode & SPI_RX_QUAD))
1512 if ((spi->mode & SPI_3WIRE) &&
1513 (xfer->rx_nbits != SPI_NBITS_SINGLE))
1519 message->status = -EINPROGRESS;
1520 return master->transfer(spi, message);
1524 * spi_async - asynchronous SPI transfer
1525 * @spi: device with which data will be exchanged
1526 * @message: describes the data transfers, including completion callback
1527 * Context: any (irqs may be blocked, etc)
1529 * This call may be used in_irq and other contexts which can't sleep,
1530 * as well as from task contexts which can sleep.
1532 * The completion callback is invoked in a context which can't sleep.
1533 * Before that invocation, the value of message->status is undefined.
1534 * When the callback is issued, message->status holds either zero (to
1535 * indicate complete success) or a negative error code. After that
1536 * callback returns, the driver which issued the transfer request may
1537 * deallocate the associated memory; it's no longer in use by any SPI
1538 * core or controller driver code.
1540 * Note that although all messages to a spi_device are handled in
1541 * FIFO order, messages may go to different devices in other orders.
1542 * Some device might be higher priority, or have various "hard" access
1543 * time requirements, for example.
1545 * On detection of any fault during the transfer, processing of
1546 * the entire message is aborted, and the device is deselected.
1547 * Until returning from the associated message completion callback,
1548 * no other spi_message queued to that device will be processed.
1549 * (This rule applies equally to all the synchronous transfer calls,
1550 * which are wrappers around this core asynchronous primitive.)
1552 int spi_async(struct spi_device *spi, struct spi_message *message)
1554 struct spi_master *master = spi->master;
1556 unsigned long flags;
1558 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1560 if (master->bus_lock_flag)
1563 ret = __spi_async(spi, message);
1565 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1569 EXPORT_SYMBOL_GPL(spi_async);
1572 * spi_async_locked - version of spi_async with exclusive bus usage
1573 * @spi: device with which data will be exchanged
1574 * @message: describes the data transfers, including completion callback
1575 * Context: any (irqs may be blocked, etc)
1577 * This call may be used in_irq and other contexts which can't sleep,
1578 * as well as from task contexts which can sleep.
1580 * The completion callback is invoked in a context which can't sleep.
1581 * Before that invocation, the value of message->status is undefined.
1582 * When the callback is issued, message->status holds either zero (to
1583 * indicate complete success) or a negative error code. After that
1584 * callback returns, the driver which issued the transfer request may
1585 * deallocate the associated memory; it's no longer in use by any SPI
1586 * core or controller driver code.
1588 * Note that although all messages to a spi_device are handled in
1589 * FIFO order, messages may go to different devices in other orders.
1590 * Some device might be higher priority, or have various "hard" access
1591 * time requirements, for example.
1593 * On detection of any fault during the transfer, processing of
1594 * the entire message is aborted, and the device is deselected.
1595 * Until returning from the associated message completion callback,
1596 * no other spi_message queued to that device will be processed.
1597 * (This rule applies equally to all the synchronous transfer calls,
1598 * which are wrappers around this core asynchronous primitive.)
1600 int spi_async_locked(struct spi_device *spi, struct spi_message *message)
1602 struct spi_master *master = spi->master;
1604 unsigned long flags;
1606 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1608 ret = __spi_async(spi, message);
1610 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1615 EXPORT_SYMBOL_GPL(spi_async_locked);
1618 /*-------------------------------------------------------------------------*/
1620 /* Utility methods for SPI master protocol drivers, layered on
1621 * top of the core. Some other utility methods are defined as
1625 static void spi_complete(void *arg)
1630 static int __spi_sync(struct spi_device *spi, struct spi_message *message,
1633 DECLARE_COMPLETION_ONSTACK(done);
1635 struct spi_master *master = spi->master;
1637 message->complete = spi_complete;
1638 message->context = &done;
1641 mutex_lock(&master->bus_lock_mutex);
1643 status = spi_async_locked(spi, message);
1646 mutex_unlock(&master->bus_lock_mutex);
1649 wait_for_completion(&done);
1650 status = message->status;
1652 message->context = NULL;
1657 * spi_sync - blocking/synchronous SPI data transfers
1658 * @spi: device with which data will be exchanged
1659 * @message: describes the data transfers
1660 * Context: can sleep
1662 * This call may only be used from a context that may sleep. The sleep
1663 * is non-interruptible, and has no timeout. Low-overhead controller
1664 * drivers may DMA directly into and out of the message buffers.
1666 * Note that the SPI device's chip select is active during the message,
1667 * and then is normally disabled between messages. Drivers for some
1668 * frequently-used devices may want to minimize costs of selecting a chip,
1669 * by leaving it selected in anticipation that the next message will go
1670 * to the same chip. (That may increase power usage.)
1672 * Also, the caller is guaranteeing that the memory associated with the
1673 * message will not be freed before this call returns.
1675 * It returns zero on success, else a negative error code.
1677 int spi_sync(struct spi_device *spi, struct spi_message *message)
1679 return __spi_sync(spi, message, 0);
1681 EXPORT_SYMBOL_GPL(spi_sync);
1684 * spi_sync_locked - version of spi_sync with exclusive bus usage
1685 * @spi: device with which data will be exchanged
1686 * @message: describes the data transfers
1687 * Context: can sleep
1689 * This call may only be used from a context that may sleep. The sleep
1690 * is non-interruptible, and has no timeout. Low-overhead controller
1691 * drivers may DMA directly into and out of the message buffers.
1693 * This call should be used by drivers that require exclusive access to the
1694 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
1695 * be released by a spi_bus_unlock call when the exclusive access is over.
1697 * It returns zero on success, else a negative error code.
1699 int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
1701 return __spi_sync(spi, message, 1);
1703 EXPORT_SYMBOL_GPL(spi_sync_locked);
1706 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
1707 * @master: SPI bus master that should be locked for exclusive bus access
1708 * Context: can sleep
1710 * This call may only be used from a context that may sleep. The sleep
1711 * is non-interruptible, and has no timeout.
1713 * This call should be used by drivers that require exclusive access to the
1714 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
1715 * exclusive access is over. Data transfer must be done by spi_sync_locked
1716 * and spi_async_locked calls when the SPI bus lock is held.
1718 * It returns zero on success, else a negative error code.
1720 int spi_bus_lock(struct spi_master *master)
1722 unsigned long flags;
1724 mutex_lock(&master->bus_lock_mutex);
1726 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1727 master->bus_lock_flag = 1;
1728 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1730 /* mutex remains locked until spi_bus_unlock is called */
1734 EXPORT_SYMBOL_GPL(spi_bus_lock);
1737 * spi_bus_unlock - release the lock for exclusive SPI bus usage
1738 * @master: SPI bus master that was locked for exclusive bus access
1739 * Context: can sleep
1741 * This call may only be used from a context that may sleep. The sleep
1742 * is non-interruptible, and has no timeout.
1744 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
1747 * It returns zero on success, else a negative error code.
1749 int spi_bus_unlock(struct spi_master *master)
1751 master->bus_lock_flag = 0;
1753 mutex_unlock(&master->bus_lock_mutex);
1757 EXPORT_SYMBOL_GPL(spi_bus_unlock);
1759 /* portable code must never pass more than 32 bytes */
1760 #define SPI_BUFSIZ max(32, SMP_CACHE_BYTES)
1765 * spi_write_then_read - SPI synchronous write followed by read
1766 * @spi: device with which data will be exchanged
1767 * @txbuf: data to be written (need not be dma-safe)
1768 * @n_tx: size of txbuf, in bytes
1769 * @rxbuf: buffer into which data will be read (need not be dma-safe)
1770 * @n_rx: size of rxbuf, in bytes
1771 * Context: can sleep
1773 * This performs a half duplex MicroWire style transaction with the
1774 * device, sending txbuf and then reading rxbuf. The return value
1775 * is zero for success, else a negative errno status code.
1776 * This call may only be used from a context that may sleep.
1778 * Parameters to this routine are always copied using a small buffer;
1779 * portable code should never use this for more than 32 bytes.
1780 * Performance-sensitive or bulk transfer code should instead use
1781 * spi_{async,sync}() calls with dma-safe buffers.
1783 int spi_write_then_read(struct spi_device *spi,
1784 const void *txbuf, unsigned n_tx,
1785 void *rxbuf, unsigned n_rx)
1787 static DEFINE_MUTEX(lock);
1790 struct spi_message message;
1791 struct spi_transfer x[2];
1794 /* Use preallocated DMA-safe buffer if we can. We can't avoid
1795 * copying here, (as a pure convenience thing), but we can
1796 * keep heap costs out of the hot path unless someone else is
1797 * using the pre-allocated buffer or the transfer is too large.
1799 if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
1800 local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx),
1801 GFP_KERNEL | GFP_DMA);
1808 spi_message_init(&message);
1809 memset(x, 0, sizeof(x));
1812 spi_message_add_tail(&x[0], &message);
1816 spi_message_add_tail(&x[1], &message);
1819 memcpy(local_buf, txbuf, n_tx);
1820 x[0].tx_buf = local_buf;
1821 x[1].rx_buf = local_buf + n_tx;
1824 status = spi_sync(spi, &message);
1826 memcpy(rxbuf, x[1].rx_buf, n_rx);
1828 if (x[0].tx_buf == buf)
1829 mutex_unlock(&lock);
1835 EXPORT_SYMBOL_GPL(spi_write_then_read);
1837 /*-------------------------------------------------------------------------*/
1839 static int __init spi_init(void)
1843 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1849 status = bus_register(&spi_bus_type);
1853 status = class_register(&spi_master_class);
1859 bus_unregister(&spi_bus_type);
1867 /* board_info is normally registered in arch_initcall(),
1868 * but even essential drivers wait till later
1870 * REVISIT only boardinfo really needs static linking. the rest (device and
1871 * driver registration) _could_ be dynamically linked (modular) ... costs
1872 * include needing to have boardinfo data structures be much more public.
1874 postcore_initcall(spi_init);