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);
62 static struct device_attribute spi_dev_attrs[] = {
67 /* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
68 * and the sysfs version makes coldplug work too.
71 static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
72 const struct spi_device *sdev)
75 if (!strcmp(sdev->modalias, id->name))
82 const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
84 const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
86 return spi_match_id(sdrv->id_table, sdev);
88 EXPORT_SYMBOL_GPL(spi_get_device_id);
90 static int spi_match_device(struct device *dev, struct device_driver *drv)
92 const struct spi_device *spi = to_spi_device(dev);
93 const struct spi_driver *sdrv = to_spi_driver(drv);
95 /* Attempt an OF style match */
96 if (of_driver_match_device(dev, drv))
100 if (acpi_driver_match_device(dev, drv))
104 return !!spi_match_id(sdrv->id_table, spi);
106 return strcmp(spi->modalias, drv->name) == 0;
109 static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
111 const struct spi_device *spi = to_spi_device(dev);
113 add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
117 #ifdef CONFIG_PM_SLEEP
118 static int spi_legacy_suspend(struct device *dev, pm_message_t message)
121 struct spi_driver *drv = to_spi_driver(dev->driver);
123 /* suspend will stop irqs and dma; no more i/o */
126 value = drv->suspend(to_spi_device(dev), message);
128 dev_dbg(dev, "... can't suspend\n");
133 static int spi_legacy_resume(struct device *dev)
136 struct spi_driver *drv = to_spi_driver(dev->driver);
138 /* resume may restart the i/o queue */
141 value = drv->resume(to_spi_device(dev));
143 dev_dbg(dev, "... can't resume\n");
148 static int spi_pm_suspend(struct device *dev)
150 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
153 return pm_generic_suspend(dev);
155 return spi_legacy_suspend(dev, PMSG_SUSPEND);
158 static int spi_pm_resume(struct device *dev)
160 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
163 return pm_generic_resume(dev);
165 return spi_legacy_resume(dev);
168 static int spi_pm_freeze(struct device *dev)
170 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
173 return pm_generic_freeze(dev);
175 return spi_legacy_suspend(dev, PMSG_FREEZE);
178 static int spi_pm_thaw(struct device *dev)
180 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
183 return pm_generic_thaw(dev);
185 return spi_legacy_resume(dev);
188 static int spi_pm_poweroff(struct device *dev)
190 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
193 return pm_generic_poweroff(dev);
195 return spi_legacy_suspend(dev, PMSG_HIBERNATE);
198 static int spi_pm_restore(struct device *dev)
200 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
203 return pm_generic_restore(dev);
205 return spi_legacy_resume(dev);
208 #define spi_pm_suspend NULL
209 #define spi_pm_resume NULL
210 #define spi_pm_freeze NULL
211 #define spi_pm_thaw NULL
212 #define spi_pm_poweroff NULL
213 #define spi_pm_restore NULL
216 static const struct dev_pm_ops spi_pm = {
217 .suspend = spi_pm_suspend,
218 .resume = spi_pm_resume,
219 .freeze = spi_pm_freeze,
221 .poweroff = spi_pm_poweroff,
222 .restore = spi_pm_restore,
224 pm_generic_runtime_suspend,
225 pm_generic_runtime_resume,
230 struct bus_type spi_bus_type = {
232 .dev_attrs = spi_dev_attrs,
233 .match = spi_match_device,
234 .uevent = spi_uevent,
237 EXPORT_SYMBOL_GPL(spi_bus_type);
240 static int spi_drv_probe(struct device *dev)
242 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
244 return sdrv->probe(to_spi_device(dev));
247 static int spi_drv_remove(struct device *dev)
249 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
251 return sdrv->remove(to_spi_device(dev));
254 static void spi_drv_shutdown(struct device *dev)
256 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
258 sdrv->shutdown(to_spi_device(dev));
262 * spi_register_driver - register a SPI driver
263 * @sdrv: the driver to register
266 int spi_register_driver(struct spi_driver *sdrv)
268 sdrv->driver.bus = &spi_bus_type;
270 sdrv->driver.probe = spi_drv_probe;
272 sdrv->driver.remove = spi_drv_remove;
274 sdrv->driver.shutdown = spi_drv_shutdown;
275 return driver_register(&sdrv->driver);
277 EXPORT_SYMBOL_GPL(spi_register_driver);
279 /*-------------------------------------------------------------------------*/
281 /* SPI devices should normally not be created by SPI device drivers; that
282 * would make them board-specific. Similarly with SPI master drivers.
283 * Device registration normally goes into like arch/.../mach.../board-YYY.c
284 * with other readonly (flashable) information about mainboard devices.
288 struct list_head list;
289 struct spi_board_info board_info;
292 static LIST_HEAD(board_list);
293 static LIST_HEAD(spi_master_list);
296 * Used to protect add/del opertion for board_info list and
297 * spi_master list, and their matching process
299 static DEFINE_MUTEX(board_lock);
302 * spi_alloc_device - Allocate a new SPI device
303 * @master: Controller to which device is connected
306 * Allows a driver to allocate and initialize a spi_device without
307 * registering it immediately. This allows a driver to directly
308 * fill the spi_device with device parameters before calling
309 * spi_add_device() on it.
311 * Caller is responsible to call spi_add_device() on the returned
312 * spi_device structure to add it to the SPI master. If the caller
313 * needs to discard the spi_device without adding it, then it should
314 * call spi_dev_put() on it.
316 * Returns a pointer to the new device, or NULL.
318 struct spi_device *spi_alloc_device(struct spi_master *master)
320 struct spi_device *spi;
321 struct device *dev = master->dev.parent;
323 if (!spi_master_get(master))
326 spi = kzalloc(sizeof *spi, GFP_KERNEL);
328 dev_err(dev, "cannot alloc spi_device\n");
329 spi_master_put(master);
333 spi->master = master;
334 spi->dev.parent = &master->dev;
335 spi->dev.bus = &spi_bus_type;
336 spi->dev.release = spidev_release;
337 spi->cs_gpio = -ENOENT;
338 device_initialize(&spi->dev);
341 EXPORT_SYMBOL_GPL(spi_alloc_device);
344 * spi_add_device - Add spi_device allocated with spi_alloc_device
345 * @spi: spi_device to register
347 * Companion function to spi_alloc_device. Devices allocated with
348 * spi_alloc_device can be added onto the spi bus with this function.
350 * Returns 0 on success; negative errno on failure
352 int spi_add_device(struct spi_device *spi)
354 static DEFINE_MUTEX(spi_add_lock);
355 struct spi_master *master = spi->master;
356 struct device *dev = master->dev.parent;
360 /* Chipselects are numbered 0..max; validate. */
361 if (spi->chip_select >= master->num_chipselect) {
362 dev_err(dev, "cs%d >= max %d\n",
364 master->num_chipselect);
368 /* Set the bus ID string */
369 dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
373 /* We need to make sure there's no other device with this
374 * chipselect **BEFORE** we call setup(), else we'll trash
375 * its configuration. Lock against concurrent add() calls.
377 mutex_lock(&spi_add_lock);
379 d = bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));
381 dev_err(dev, "chipselect %d already in use\n",
388 if (master->cs_gpios)
389 spi->cs_gpio = master->cs_gpios[spi->chip_select];
391 /* Drivers may modify this initial i/o setup, but will
392 * normally rely on the device being setup. Devices
393 * using SPI_CS_HIGH can't coexist well otherwise...
395 status = spi_setup(spi);
397 dev_err(dev, "can't setup %s, status %d\n",
398 dev_name(&spi->dev), status);
402 /* Device may be bound to an active driver when this returns */
403 status = device_add(&spi->dev);
405 dev_err(dev, "can't add %s, status %d\n",
406 dev_name(&spi->dev), status);
408 dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
411 mutex_unlock(&spi_add_lock);
414 EXPORT_SYMBOL_GPL(spi_add_device);
417 * spi_new_device - instantiate one new SPI device
418 * @master: Controller to which device is connected
419 * @chip: Describes the SPI device
422 * On typical mainboards, this is purely internal; and it's not needed
423 * after board init creates the hard-wired devices. Some development
424 * platforms may not be able to use spi_register_board_info though, and
425 * this is exported so that for example a USB or parport based adapter
426 * driver could add devices (which it would learn about out-of-band).
428 * Returns the new device, or NULL.
430 struct spi_device *spi_new_device(struct spi_master *master,
431 struct spi_board_info *chip)
433 struct spi_device *proxy;
436 /* NOTE: caller did any chip->bus_num checks necessary.
438 * Also, unless we change the return value convention to use
439 * error-or-pointer (not NULL-or-pointer), troubleshootability
440 * suggests syslogged diagnostics are best here (ugh).
443 proxy = spi_alloc_device(master);
447 WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
449 proxy->chip_select = chip->chip_select;
450 proxy->max_speed_hz = chip->max_speed_hz;
451 proxy->mode = chip->mode;
452 proxy->irq = chip->irq;
453 strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
454 proxy->dev.platform_data = (void *) chip->platform_data;
455 proxy->controller_data = chip->controller_data;
456 proxy->controller_state = NULL;
458 status = spi_add_device(proxy);
466 EXPORT_SYMBOL_GPL(spi_new_device);
468 static void spi_match_master_to_boardinfo(struct spi_master *master,
469 struct spi_board_info *bi)
471 struct spi_device *dev;
473 if (master->bus_num != bi->bus_num)
476 dev = spi_new_device(master, bi);
478 dev_err(master->dev.parent, "can't create new device for %s\n",
483 * spi_register_board_info - register SPI devices for a given board
484 * @info: array of chip descriptors
485 * @n: how many descriptors are provided
488 * Board-specific early init code calls this (probably during arch_initcall)
489 * with segments of the SPI device table. Any device nodes are created later,
490 * after the relevant parent SPI controller (bus_num) is defined. We keep
491 * this table of devices forever, so that reloading a controller driver will
492 * not make Linux forget about these hard-wired devices.
494 * Other code can also call this, e.g. a particular add-on board might provide
495 * SPI devices through its expansion connector, so code initializing that board
496 * would naturally declare its SPI devices.
498 * The board info passed can safely be __initdata ... but be careful of
499 * any embedded pointers (platform_data, etc), they're copied as-is.
501 int spi_register_board_info(struct spi_board_info const *info, unsigned n)
503 struct boardinfo *bi;
506 bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
510 for (i = 0; i < n; i++, bi++, info++) {
511 struct spi_master *master;
513 memcpy(&bi->board_info, info, sizeof(*info));
514 mutex_lock(&board_lock);
515 list_add_tail(&bi->list, &board_list);
516 list_for_each_entry(master, &spi_master_list, list)
517 spi_match_master_to_boardinfo(master, &bi->board_info);
518 mutex_unlock(&board_lock);
524 /*-------------------------------------------------------------------------*/
527 * spi_pump_messages - kthread work function which processes spi message queue
528 * @work: pointer to kthread work struct contained in the master struct
530 * This function checks if there is any spi message in the queue that
531 * needs processing and if so call out to the driver to initialize hardware
532 * and transfer each message.
535 static void spi_pump_messages(struct kthread_work *work)
537 struct spi_master *master =
538 container_of(work, struct spi_master, pump_messages);
540 bool was_busy = false;
543 /* Lock queue and check for queue work */
544 spin_lock_irqsave(&master->queue_lock, flags);
545 if (list_empty(&master->queue) || !master->running) {
547 spin_unlock_irqrestore(&master->queue_lock, flags);
550 master->busy = false;
551 spin_unlock_irqrestore(&master->queue_lock, flags);
552 if (master->unprepare_transfer_hardware &&
553 master->unprepare_transfer_hardware(master))
554 dev_err(&master->dev,
555 "failed to unprepare transfer hardware\n");
556 if (master->auto_runtime_pm) {
557 pm_runtime_mark_last_busy(master->dev.parent);
558 pm_runtime_put_autosuspend(master->dev.parent);
563 /* Make sure we are not already running a message */
564 if (master->cur_msg) {
565 spin_unlock_irqrestore(&master->queue_lock, flags);
568 /* Extract head of queue */
570 list_entry(master->queue.next, struct spi_message, queue);
572 list_del_init(&master->cur_msg->queue);
577 spin_unlock_irqrestore(&master->queue_lock, flags);
579 if (!was_busy && master->auto_runtime_pm) {
580 ret = pm_runtime_get_sync(master->dev.parent);
582 dev_err(&master->dev, "Failed to power device: %d\n",
588 if (!was_busy && master->prepare_transfer_hardware) {
589 ret = master->prepare_transfer_hardware(master);
591 dev_err(&master->dev,
592 "failed to prepare transfer hardware\n");
594 if (master->auto_runtime_pm)
595 pm_runtime_put(master->dev.parent);
600 ret = master->transfer_one_message(master, master->cur_msg);
602 dev_err(&master->dev,
603 "failed to transfer one message from queue\n");
608 static int spi_init_queue(struct spi_master *master)
610 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
612 INIT_LIST_HEAD(&master->queue);
613 spin_lock_init(&master->queue_lock);
615 master->running = false;
616 master->busy = false;
618 init_kthread_worker(&master->kworker);
619 master->kworker_task = kthread_run(kthread_worker_fn,
620 &master->kworker, "%s",
621 dev_name(&master->dev));
622 if (IS_ERR(master->kworker_task)) {
623 dev_err(&master->dev, "failed to create message pump task\n");
626 init_kthread_work(&master->pump_messages, spi_pump_messages);
629 * Master config will indicate if this controller should run the
630 * message pump with high (realtime) priority to reduce the transfer
631 * latency on the bus by minimising the delay between a transfer
632 * request and the scheduling of the message pump thread. Without this
633 * setting the message pump thread will remain at default priority.
636 dev_info(&master->dev,
637 "will run message pump with realtime priority\n");
638 sched_setscheduler(master->kworker_task, SCHED_FIFO, ¶m);
645 * spi_get_next_queued_message() - called by driver to check for queued
647 * @master: the master to check for queued messages
649 * If there are more messages in the queue, the next message is returned from
652 struct spi_message *spi_get_next_queued_message(struct spi_master *master)
654 struct spi_message *next;
657 /* get a pointer to the next message, if any */
658 spin_lock_irqsave(&master->queue_lock, flags);
659 if (list_empty(&master->queue))
662 next = list_entry(master->queue.next,
663 struct spi_message, queue);
664 spin_unlock_irqrestore(&master->queue_lock, flags);
668 EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
671 * spi_finalize_current_message() - the current message is complete
672 * @master: the master to return the message to
674 * Called by the driver to notify the core that the message in the front of the
675 * queue is complete and can be removed from the queue.
677 void spi_finalize_current_message(struct spi_master *master)
679 struct spi_message *mesg;
682 spin_lock_irqsave(&master->queue_lock, flags);
683 mesg = master->cur_msg;
684 master->cur_msg = NULL;
686 queue_kthread_work(&master->kworker, &master->pump_messages);
687 spin_unlock_irqrestore(&master->queue_lock, flags);
691 mesg->complete(mesg->context);
693 EXPORT_SYMBOL_GPL(spi_finalize_current_message);
695 static int spi_start_queue(struct spi_master *master)
699 spin_lock_irqsave(&master->queue_lock, flags);
701 if (master->running || master->busy) {
702 spin_unlock_irqrestore(&master->queue_lock, flags);
706 master->running = true;
707 master->cur_msg = NULL;
708 spin_unlock_irqrestore(&master->queue_lock, flags);
710 queue_kthread_work(&master->kworker, &master->pump_messages);
715 static int spi_stop_queue(struct spi_master *master)
718 unsigned limit = 500;
721 spin_lock_irqsave(&master->queue_lock, flags);
724 * This is a bit lame, but is optimized for the common execution path.
725 * A wait_queue on the master->busy could be used, but then the common
726 * execution path (pump_messages) would be required to call wake_up or
727 * friends on every SPI message. Do this instead.
729 while ((!list_empty(&master->queue) || master->busy) && limit--) {
730 spin_unlock_irqrestore(&master->queue_lock, flags);
732 spin_lock_irqsave(&master->queue_lock, flags);
735 if (!list_empty(&master->queue) || master->busy)
738 master->running = false;
740 spin_unlock_irqrestore(&master->queue_lock, flags);
743 dev_warn(&master->dev,
744 "could not stop message queue\n");
750 static int spi_destroy_queue(struct spi_master *master)
754 ret = spi_stop_queue(master);
757 * flush_kthread_worker will block until all work is done.
758 * If the reason that stop_queue timed out is that the work will never
759 * finish, then it does no good to call flush/stop thread, so
763 dev_err(&master->dev, "problem destroying queue\n");
767 flush_kthread_worker(&master->kworker);
768 kthread_stop(master->kworker_task);
774 * spi_queued_transfer - transfer function for queued transfers
775 * @spi: spi device which is requesting transfer
776 * @msg: spi message which is to handled is queued to driver queue
778 static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
780 struct spi_master *master = spi->master;
783 spin_lock_irqsave(&master->queue_lock, flags);
785 if (!master->running) {
786 spin_unlock_irqrestore(&master->queue_lock, flags);
789 msg->actual_length = 0;
790 msg->status = -EINPROGRESS;
792 list_add_tail(&msg->queue, &master->queue);
793 if (master->running && !master->busy)
794 queue_kthread_work(&master->kworker, &master->pump_messages);
796 spin_unlock_irqrestore(&master->queue_lock, flags);
800 static int spi_master_initialize_queue(struct spi_master *master)
804 master->queued = true;
805 master->transfer = spi_queued_transfer;
807 /* Initialize and start queue */
808 ret = spi_init_queue(master);
810 dev_err(&master->dev, "problem initializing queue\n");
813 ret = spi_start_queue(master);
815 dev_err(&master->dev, "problem starting queue\n");
816 goto err_start_queue;
823 spi_destroy_queue(master);
827 /*-------------------------------------------------------------------------*/
829 #if defined(CONFIG_OF)
831 * of_register_spi_devices() - Register child devices onto the SPI bus
832 * @master: Pointer to spi_master device
834 * Registers an spi_device for each child node of master node which has a 'reg'
837 static void of_register_spi_devices(struct spi_master *master)
839 struct spi_device *spi;
840 struct device_node *nc;
842 char modalias[SPI_NAME_SIZE + 4];
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 prop = of_get_property(nc, "reg", &len);
870 if (!prop || len < sizeof(*prop)) {
871 dev_err(&master->dev, "%s has no 'reg' property\n",
876 spi->chip_select = be32_to_cpup(prop);
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 prop = of_get_property(nc, "spi-tx-nbits", &len);
890 if (!prop || len < sizeof(*prop)) {
891 dev_err(&master->dev, "%s has no 'spi-tx-nbits' property\n",
896 switch (be32_to_cpup(prop)) {
897 case SPI_NBITS_SINGLE:
900 spi->mode |= SPI_TX_DUAL;
903 spi->mode |= SPI_TX_QUAD;
906 dev_err(&master->dev, "spi-tx-nbits value is not supported\n");
911 prop = of_get_property(nc, "spi-rx-nbits", &len);
912 if (!prop || len < sizeof(*prop)) {
913 dev_err(&master->dev, "%s has no 'spi-rx-nbits' property\n",
918 switch (be32_to_cpup(prop)) {
919 case SPI_NBITS_SINGLE:
922 spi->mode |= SPI_RX_DUAL;
925 spi->mode |= SPI_RX_QUAD;
928 dev_err(&master->dev, "spi-rx-nbits value is not supported\n");
934 prop = of_get_property(nc, "spi-max-frequency", &len);
935 if (!prop || len < sizeof(*prop)) {
936 dev_err(&master->dev, "%s has no 'spi-max-frequency' property\n",
941 spi->max_speed_hz = be32_to_cpup(prop);
944 spi->irq = irq_of_parse_and_map(nc, 0);
946 /* Store a pointer to the node in the device structure */
948 spi->dev.of_node = nc;
950 /* Register the new device */
951 snprintf(modalias, sizeof(modalias), "%s%s", SPI_MODULE_PREFIX,
953 request_module(modalias);
954 rc = spi_add_device(spi);
956 dev_err(&master->dev, "spi_device register error %s\n",
964 static void of_register_spi_devices(struct spi_master *master) { }
968 static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
970 struct spi_device *spi = data;
972 if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
973 struct acpi_resource_spi_serialbus *sb;
975 sb = &ares->data.spi_serial_bus;
976 if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
977 spi->chip_select = sb->device_selection;
978 spi->max_speed_hz = sb->connection_speed;
980 if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
981 spi->mode |= SPI_CPHA;
982 if (sb->clock_polarity == ACPI_SPI_START_HIGH)
983 spi->mode |= SPI_CPOL;
984 if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
985 spi->mode |= SPI_CS_HIGH;
987 } else if (spi->irq < 0) {
990 if (acpi_dev_resource_interrupt(ares, 0, &r))
994 /* Always tell the ACPI core to skip this resource */
998 static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
999 void *data, void **return_value)
1001 struct spi_master *master = data;
1002 struct list_head resource_list;
1003 struct acpi_device *adev;
1004 struct spi_device *spi;
1007 if (acpi_bus_get_device(handle, &adev))
1009 if (acpi_bus_get_status(adev) || !adev->status.present)
1012 spi = spi_alloc_device(master);
1014 dev_err(&master->dev, "failed to allocate SPI device for %s\n",
1015 dev_name(&adev->dev));
1016 return AE_NO_MEMORY;
1019 ACPI_HANDLE_SET(&spi->dev, handle);
1022 INIT_LIST_HEAD(&resource_list);
1023 ret = acpi_dev_get_resources(adev, &resource_list,
1024 acpi_spi_add_resource, spi);
1025 acpi_dev_free_resource_list(&resource_list);
1027 if (ret < 0 || !spi->max_speed_hz) {
1032 strlcpy(spi->modalias, dev_name(&adev->dev), sizeof(spi->modalias));
1033 if (spi_add_device(spi)) {
1034 dev_err(&master->dev, "failed to add SPI device %s from ACPI\n",
1035 dev_name(&adev->dev));
1042 static void acpi_register_spi_devices(struct spi_master *master)
1047 handle = ACPI_HANDLE(master->dev.parent);
1051 status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
1052 acpi_spi_add_device, NULL,
1054 if (ACPI_FAILURE(status))
1055 dev_warn(&master->dev, "failed to enumerate SPI slaves\n");
1058 static inline void acpi_register_spi_devices(struct spi_master *master) {}
1059 #endif /* CONFIG_ACPI */
1061 static void spi_master_release(struct device *dev)
1063 struct spi_master *master;
1065 master = container_of(dev, struct spi_master, dev);
1069 static struct class spi_master_class = {
1070 .name = "spi_master",
1071 .owner = THIS_MODULE,
1072 .dev_release = spi_master_release,
1078 * spi_alloc_master - allocate SPI master controller
1079 * @dev: the controller, possibly using the platform_bus
1080 * @size: how much zeroed driver-private data to allocate; the pointer to this
1081 * memory is in the driver_data field of the returned device,
1082 * accessible with spi_master_get_devdata().
1083 * Context: can sleep
1085 * This call is used only by SPI master controller drivers, which are the
1086 * only ones directly touching chip registers. It's how they allocate
1087 * an spi_master structure, prior to calling spi_register_master().
1089 * This must be called from context that can sleep. It returns the SPI
1090 * master structure on success, else NULL.
1092 * The caller is responsible for assigning the bus number and initializing
1093 * the master's methods before calling spi_register_master(); and (after errors
1094 * adding the device) calling spi_master_put() and kfree() to prevent a memory
1097 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
1099 struct spi_master *master;
1104 master = kzalloc(size + sizeof *master, GFP_KERNEL);
1108 device_initialize(&master->dev);
1109 master->bus_num = -1;
1110 master->num_chipselect = 1;
1111 master->dev.class = &spi_master_class;
1112 master->dev.parent = get_device(dev);
1113 spi_master_set_devdata(master, &master[1]);
1117 EXPORT_SYMBOL_GPL(spi_alloc_master);
1120 static int of_spi_register_master(struct spi_master *master)
1123 struct device_node *np = master->dev.of_node;
1128 nb = of_gpio_named_count(np, "cs-gpios");
1129 master->num_chipselect = max(nb, (int)master->num_chipselect);
1131 /* Return error only for an incorrectly formed cs-gpios property */
1132 if (nb == 0 || nb == -ENOENT)
1137 cs = devm_kzalloc(&master->dev,
1138 sizeof(int) * master->num_chipselect,
1140 master->cs_gpios = cs;
1142 if (!master->cs_gpios)
1145 for (i = 0; i < master->num_chipselect; i++)
1148 for (i = 0; i < nb; i++)
1149 cs[i] = of_get_named_gpio(np, "cs-gpios", i);
1154 static int of_spi_register_master(struct spi_master *master)
1161 * spi_register_master - register SPI master controller
1162 * @master: initialized master, originally from spi_alloc_master()
1163 * Context: can sleep
1165 * SPI master controllers connect to their drivers using some non-SPI bus,
1166 * such as the platform bus. The final stage of probe() in that code
1167 * includes calling spi_register_master() to hook up to this SPI bus glue.
1169 * SPI controllers use board specific (often SOC specific) bus numbers,
1170 * and board-specific addressing for SPI devices combines those numbers
1171 * with chip select numbers. Since SPI does not directly support dynamic
1172 * device identification, boards need configuration tables telling which
1173 * chip is at which address.
1175 * This must be called from context that can sleep. It returns zero on
1176 * success, else a negative error code (dropping the master's refcount).
1177 * After a successful return, the caller is responsible for calling
1178 * spi_unregister_master().
1180 int spi_register_master(struct spi_master *master)
1182 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
1183 struct device *dev = master->dev.parent;
1184 struct boardinfo *bi;
1185 int status = -ENODEV;
1191 status = of_spi_register_master(master);
1195 /* even if it's just one always-selected device, there must
1196 * be at least one chipselect
1198 if (master->num_chipselect == 0)
1201 if ((master->bus_num < 0) && master->dev.of_node)
1202 master->bus_num = of_alias_get_id(master->dev.of_node, "spi");
1204 /* convention: dynamically assigned bus IDs count down from the max */
1205 if (master->bus_num < 0) {
1206 /* FIXME switch to an IDR based scheme, something like
1207 * I2C now uses, so we can't run out of "dynamic" IDs
1209 master->bus_num = atomic_dec_return(&dyn_bus_id);
1213 spin_lock_init(&master->bus_lock_spinlock);
1214 mutex_init(&master->bus_lock_mutex);
1215 master->bus_lock_flag = 0;
1217 /* register the device, then userspace will see it.
1218 * registration fails if the bus ID is in use.
1220 dev_set_name(&master->dev, "spi%u", master->bus_num);
1221 status = device_add(&master->dev);
1224 dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
1225 dynamic ? " (dynamic)" : "");
1227 /* If we're using a queued driver, start the queue */
1228 if (master->transfer)
1229 dev_info(dev, "master is unqueued, this is deprecated\n");
1231 status = spi_master_initialize_queue(master);
1233 device_unregister(&master->dev);
1238 mutex_lock(&board_lock);
1239 list_add_tail(&master->list, &spi_master_list);
1240 list_for_each_entry(bi, &board_list, list)
1241 spi_match_master_to_boardinfo(master, &bi->board_info);
1242 mutex_unlock(&board_lock);
1244 /* Register devices from the device tree and ACPI */
1245 of_register_spi_devices(master);
1246 acpi_register_spi_devices(master);
1250 EXPORT_SYMBOL_GPL(spi_register_master);
1252 static int __unregister(struct device *dev, void *null)
1254 spi_unregister_device(to_spi_device(dev));
1259 * spi_unregister_master - unregister SPI master controller
1260 * @master: the master being unregistered
1261 * Context: can sleep
1263 * This call is used only by SPI master controller drivers, which are the
1264 * only ones directly touching chip registers.
1266 * This must be called from context that can sleep.
1268 void spi_unregister_master(struct spi_master *master)
1272 if (master->queued) {
1273 if (spi_destroy_queue(master))
1274 dev_err(&master->dev, "queue remove failed\n");
1277 mutex_lock(&board_lock);
1278 list_del(&master->list);
1279 mutex_unlock(&board_lock);
1281 dummy = device_for_each_child(&master->dev, NULL, __unregister);
1282 device_unregister(&master->dev);
1284 EXPORT_SYMBOL_GPL(spi_unregister_master);
1286 int spi_master_suspend(struct spi_master *master)
1290 /* Basically no-ops for non-queued masters */
1291 if (!master->queued)
1294 ret = spi_stop_queue(master);
1296 dev_err(&master->dev, "queue stop failed\n");
1300 EXPORT_SYMBOL_GPL(spi_master_suspend);
1302 int spi_master_resume(struct spi_master *master)
1306 if (!master->queued)
1309 ret = spi_start_queue(master);
1311 dev_err(&master->dev, "queue restart failed\n");
1315 EXPORT_SYMBOL_GPL(spi_master_resume);
1317 static int __spi_master_match(struct device *dev, const void *data)
1319 struct spi_master *m;
1320 const u16 *bus_num = data;
1322 m = container_of(dev, struct spi_master, dev);
1323 return m->bus_num == *bus_num;
1327 * spi_busnum_to_master - look up master associated with bus_num
1328 * @bus_num: the master's bus number
1329 * Context: can sleep
1331 * This call may be used with devices that are registered after
1332 * arch init time. It returns a refcounted pointer to the relevant
1333 * spi_master (which the caller must release), or NULL if there is
1334 * no such master registered.
1336 struct spi_master *spi_busnum_to_master(u16 bus_num)
1339 struct spi_master *master = NULL;
1341 dev = class_find_device(&spi_master_class, NULL, &bus_num,
1342 __spi_master_match);
1344 master = container_of(dev, struct spi_master, dev);
1345 /* reference got in class_find_device */
1348 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
1351 /*-------------------------------------------------------------------------*/
1353 /* Core methods for SPI master protocol drivers. Some of the
1354 * other core methods are currently defined as inline functions.
1358 * spi_setup - setup SPI mode and clock rate
1359 * @spi: the device whose settings are being modified
1360 * Context: can sleep, and no requests are queued to the device
1362 * SPI protocol drivers may need to update the transfer mode if the
1363 * device doesn't work with its default. They may likewise need
1364 * to update clock rates or word sizes from initial values. This function
1365 * changes those settings, and must be called from a context that can sleep.
1366 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
1367 * effect the next time the device is selected and data is transferred to
1368 * or from it. When this function returns, the spi device is deselected.
1370 * Note that this call will fail if the protocol driver specifies an option
1371 * that the underlying controller or its driver does not support. For
1372 * example, not all hardware supports wire transfers using nine bit words,
1373 * LSB-first wire encoding, or active-high chipselects.
1375 int spi_setup(struct spi_device *spi)
1380 /* check mode to prevent that DUAL and QUAD set at the same time
1382 if (((spi->mode & SPI_TX_DUAL) && (spi->mode & SPI_TX_QUAD)) ||
1383 ((spi->mode & SPI_RX_DUAL) && (spi->mode & SPI_RX_QUAD))) {
1385 "setup: can not select dual and quad at the same time\n");
1388 /* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
1390 if ((spi->mode & SPI_3WIRE) && (spi->mode &
1391 (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)))
1393 /* help drivers fail *cleanly* when they need options
1394 * that aren't supported with their current master
1396 bad_bits = spi->mode & ~spi->master->mode_bits;
1398 dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
1403 if (!spi->bits_per_word)
1404 spi->bits_per_word = 8;
1406 if (spi->master->setup)
1407 status = spi->master->setup(spi);
1409 dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
1410 "%u bits/w, %u Hz max --> %d\n",
1411 (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
1412 (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
1413 (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
1414 (spi->mode & SPI_3WIRE) ? "3wire, " : "",
1415 (spi->mode & SPI_LOOP) ? "loopback, " : "",
1416 spi->bits_per_word, spi->max_speed_hz,
1421 EXPORT_SYMBOL_GPL(spi_setup);
1423 static int __spi_async(struct spi_device *spi, struct spi_message *message)
1425 struct spi_master *master = spi->master;
1426 struct spi_transfer *xfer;
1428 if (list_empty(&message->transfers))
1430 if (!message->complete)
1433 /* Half-duplex links include original MicroWire, and ones with
1434 * only one data pin like SPI_3WIRE (switches direction) or where
1435 * either MOSI or MISO is missing. They can also be caused by
1436 * software limitations.
1438 if ((master->flags & SPI_MASTER_HALF_DUPLEX)
1439 || (spi->mode & SPI_3WIRE)) {
1440 unsigned flags = master->flags;
1442 list_for_each_entry(xfer, &message->transfers, transfer_list) {
1443 if (xfer->rx_buf && xfer->tx_buf)
1445 if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
1447 if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
1453 * Set transfer bits_per_word and max speed as spi device default if
1454 * it is not set for this transfer.
1455 * Set transfer tx_nbits and rx_nbits as single transfer default
1456 * (SPI_NBITS_SINGLE) if it is not set for this transfer.
1458 list_for_each_entry(xfer, &message->transfers, transfer_list) {
1459 if (!xfer->bits_per_word)
1460 xfer->bits_per_word = spi->bits_per_word;
1461 if (!xfer->speed_hz) {
1462 xfer->speed_hz = spi->max_speed_hz;
1463 if (master->max_speed_hz &&
1464 xfer->speed_hz > master->max_speed_hz)
1465 xfer->speed_hz = master->max_speed_hz;
1468 if (master->bits_per_word_mask) {
1469 /* Only 32 bits fit in the mask */
1470 if (xfer->bits_per_word > 32)
1472 if (!(master->bits_per_word_mask &
1473 BIT(xfer->bits_per_word - 1)))
1477 if (xfer->speed_hz && master->min_speed_hz &&
1478 xfer->speed_hz < master->min_speed_hz)
1480 if (xfer->speed_hz && master->max_speed_hz &&
1481 xfer->speed_hz > master->max_speed_hz)
1483 if (xfer->tx_buf && !xfer->tx_nbits)
1484 xfer->tx_nbits = SPI_NBITS_SINGLE;
1485 if (xfer->rx_buf && !xfer->rx_nbits)
1486 xfer->rx_nbits = SPI_NBITS_SINGLE;
1487 /* check transfer tx/rx_nbits:
1488 * 1. keep the value is not out of single, dual and quad
1489 * 2. keep tx/rx_nbits is contained by mode in spi_device
1490 * 3. if SPI_3WIRE, tx/rx_nbits should be in single
1493 if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
1494 xfer->tx_nbits != SPI_NBITS_DUAL &&
1495 xfer->tx_nbits != SPI_NBITS_QUAD)
1497 if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
1498 !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
1500 if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
1501 !(spi->mode & SPI_TX_QUAD))
1503 if ((spi->mode & SPI_3WIRE) &&
1504 (xfer->tx_nbits != SPI_NBITS_SINGLE))
1507 /* check transfer rx_nbits */
1509 if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
1510 xfer->rx_nbits != SPI_NBITS_DUAL &&
1511 xfer->rx_nbits != SPI_NBITS_QUAD)
1513 if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
1514 !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
1516 if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
1517 !(spi->mode & SPI_RX_QUAD))
1519 if ((spi->mode & SPI_3WIRE) &&
1520 (xfer->rx_nbits != SPI_NBITS_SINGLE))
1526 message->status = -EINPROGRESS;
1527 return master->transfer(spi, message);
1531 * spi_async - asynchronous SPI transfer
1532 * @spi: device with which data will be exchanged
1533 * @message: describes the data transfers, including completion callback
1534 * Context: any (irqs may be blocked, etc)
1536 * This call may be used in_irq and other contexts which can't sleep,
1537 * as well as from task contexts which can sleep.
1539 * The completion callback is invoked in a context which can't sleep.
1540 * Before that invocation, the value of message->status is undefined.
1541 * When the callback is issued, message->status holds either zero (to
1542 * indicate complete success) or a negative error code. After that
1543 * callback returns, the driver which issued the transfer request may
1544 * deallocate the associated memory; it's no longer in use by any SPI
1545 * core or controller driver code.
1547 * Note that although all messages to a spi_device are handled in
1548 * FIFO order, messages may go to different devices in other orders.
1549 * Some device might be higher priority, or have various "hard" access
1550 * time requirements, for example.
1552 * On detection of any fault during the transfer, processing of
1553 * the entire message is aborted, and the device is deselected.
1554 * Until returning from the associated message completion callback,
1555 * no other spi_message queued to that device will be processed.
1556 * (This rule applies equally to all the synchronous transfer calls,
1557 * which are wrappers around this core asynchronous primitive.)
1559 int spi_async(struct spi_device *spi, struct spi_message *message)
1561 struct spi_master *master = spi->master;
1563 unsigned long flags;
1565 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1567 if (master->bus_lock_flag)
1570 ret = __spi_async(spi, message);
1572 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1576 EXPORT_SYMBOL_GPL(spi_async);
1579 * spi_async_locked - version of spi_async with exclusive bus usage
1580 * @spi: device with which data will be exchanged
1581 * @message: describes the data transfers, including completion callback
1582 * Context: any (irqs may be blocked, etc)
1584 * This call may be used in_irq and other contexts which can't sleep,
1585 * as well as from task contexts which can sleep.
1587 * The completion callback is invoked in a context which can't sleep.
1588 * Before that invocation, the value of message->status is undefined.
1589 * When the callback is issued, message->status holds either zero (to
1590 * indicate complete success) or a negative error code. After that
1591 * callback returns, the driver which issued the transfer request may
1592 * deallocate the associated memory; it's no longer in use by any SPI
1593 * core or controller driver code.
1595 * Note that although all messages to a spi_device are handled in
1596 * FIFO order, messages may go to different devices in other orders.
1597 * Some device might be higher priority, or have various "hard" access
1598 * time requirements, for example.
1600 * On detection of any fault during the transfer, processing of
1601 * the entire message is aborted, and the device is deselected.
1602 * Until returning from the associated message completion callback,
1603 * no other spi_message queued to that device will be processed.
1604 * (This rule applies equally to all the synchronous transfer calls,
1605 * which are wrappers around this core asynchronous primitive.)
1607 int spi_async_locked(struct spi_device *spi, struct spi_message *message)
1609 struct spi_master *master = spi->master;
1611 unsigned long flags;
1613 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1615 ret = __spi_async(spi, message);
1617 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1622 EXPORT_SYMBOL_GPL(spi_async_locked);
1625 /*-------------------------------------------------------------------------*/
1627 /* Utility methods for SPI master protocol drivers, layered on
1628 * top of the core. Some other utility methods are defined as
1632 static void spi_complete(void *arg)
1637 static int __spi_sync(struct spi_device *spi, struct spi_message *message,
1640 DECLARE_COMPLETION_ONSTACK(done);
1642 struct spi_master *master = spi->master;
1644 message->complete = spi_complete;
1645 message->context = &done;
1648 mutex_lock(&master->bus_lock_mutex);
1650 status = spi_async_locked(spi, message);
1653 mutex_unlock(&master->bus_lock_mutex);
1656 wait_for_completion(&done);
1657 status = message->status;
1659 message->context = NULL;
1664 * spi_sync - blocking/synchronous SPI data transfers
1665 * @spi: device with which data will be exchanged
1666 * @message: describes the data transfers
1667 * Context: can sleep
1669 * This call may only be used from a context that may sleep. The sleep
1670 * is non-interruptible, and has no timeout. Low-overhead controller
1671 * drivers may DMA directly into and out of the message buffers.
1673 * Note that the SPI device's chip select is active during the message,
1674 * and then is normally disabled between messages. Drivers for some
1675 * frequently-used devices may want to minimize costs of selecting a chip,
1676 * by leaving it selected in anticipation that the next message will go
1677 * to the same chip. (That may increase power usage.)
1679 * Also, the caller is guaranteeing that the memory associated with the
1680 * message will not be freed before this call returns.
1682 * It returns zero on success, else a negative error code.
1684 int spi_sync(struct spi_device *spi, struct spi_message *message)
1686 return __spi_sync(spi, message, 0);
1688 EXPORT_SYMBOL_GPL(spi_sync);
1691 * spi_sync_locked - version of spi_sync with exclusive bus usage
1692 * @spi: device with which data will be exchanged
1693 * @message: describes the data transfers
1694 * Context: can sleep
1696 * This call may only be used from a context that may sleep. The sleep
1697 * is non-interruptible, and has no timeout. Low-overhead controller
1698 * drivers may DMA directly into and out of the message buffers.
1700 * This call should be used by drivers that require exclusive access to the
1701 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
1702 * be released by a spi_bus_unlock call when the exclusive access is over.
1704 * It returns zero on success, else a negative error code.
1706 int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
1708 return __spi_sync(spi, message, 1);
1710 EXPORT_SYMBOL_GPL(spi_sync_locked);
1713 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
1714 * @master: SPI bus master that should be locked for exclusive bus access
1715 * Context: can sleep
1717 * This call may only be used from a context that may sleep. The sleep
1718 * is non-interruptible, and has no timeout.
1720 * This call should be used by drivers that require exclusive access to the
1721 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
1722 * exclusive access is over. Data transfer must be done by spi_sync_locked
1723 * and spi_async_locked calls when the SPI bus lock is held.
1725 * It returns zero on success, else a negative error code.
1727 int spi_bus_lock(struct spi_master *master)
1729 unsigned long flags;
1731 mutex_lock(&master->bus_lock_mutex);
1733 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1734 master->bus_lock_flag = 1;
1735 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1737 /* mutex remains locked until spi_bus_unlock is called */
1741 EXPORT_SYMBOL_GPL(spi_bus_lock);
1744 * spi_bus_unlock - release the lock for exclusive SPI bus usage
1745 * @master: SPI bus master that was locked for exclusive bus access
1746 * Context: can sleep
1748 * This call may only be used from a context that may sleep. The sleep
1749 * is non-interruptible, and has no timeout.
1751 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
1754 * It returns zero on success, else a negative error code.
1756 int spi_bus_unlock(struct spi_master *master)
1758 master->bus_lock_flag = 0;
1760 mutex_unlock(&master->bus_lock_mutex);
1764 EXPORT_SYMBOL_GPL(spi_bus_unlock);
1766 /* portable code must never pass more than 32 bytes */
1767 #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
1772 * spi_write_then_read - SPI synchronous write followed by read
1773 * @spi: device with which data will be exchanged
1774 * @txbuf: data to be written (need not be dma-safe)
1775 * @n_tx: size of txbuf, in bytes
1776 * @rxbuf: buffer into which data will be read (need not be dma-safe)
1777 * @n_rx: size of rxbuf, in bytes
1778 * Context: can sleep
1780 * This performs a half duplex MicroWire style transaction with the
1781 * device, sending txbuf and then reading rxbuf. The return value
1782 * is zero for success, else a negative errno status code.
1783 * This call may only be used from a context that may sleep.
1785 * Parameters to this routine are always copied using a small buffer;
1786 * portable code should never use this for more than 32 bytes.
1787 * Performance-sensitive or bulk transfer code should instead use
1788 * spi_{async,sync}() calls with dma-safe buffers.
1790 int spi_write_then_read(struct spi_device *spi,
1791 const void *txbuf, unsigned n_tx,
1792 void *rxbuf, unsigned n_rx)
1794 static DEFINE_MUTEX(lock);
1797 struct spi_message message;
1798 struct spi_transfer x[2];
1801 /* Use preallocated DMA-safe buffer if we can. We can't avoid
1802 * copying here, (as a pure convenience thing), but we can
1803 * keep heap costs out of the hot path unless someone else is
1804 * using the pre-allocated buffer or the transfer is too large.
1806 if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
1807 local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx),
1808 GFP_KERNEL | GFP_DMA);
1815 spi_message_init(&message);
1816 memset(x, 0, sizeof x);
1819 spi_message_add_tail(&x[0], &message);
1823 spi_message_add_tail(&x[1], &message);
1826 memcpy(local_buf, txbuf, n_tx);
1827 x[0].tx_buf = local_buf;
1828 x[1].rx_buf = local_buf + n_tx;
1831 status = spi_sync(spi, &message);
1833 memcpy(rxbuf, x[1].rx_buf, n_rx);
1835 if (x[0].tx_buf == buf)
1836 mutex_unlock(&lock);
1842 EXPORT_SYMBOL_GPL(spi_write_then_read);
1844 /*-------------------------------------------------------------------------*/
1846 static int __init spi_init(void)
1850 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1856 status = bus_register(&spi_bus_type);
1860 status = class_register(&spi_master_class);
1866 bus_unregister(&spi_bus_type);
1874 /* board_info is normally registered in arch_initcall(),
1875 * but even essential drivers wait till later
1877 * REVISIT only boardinfo really needs static linking. the rest (device and
1878 * driver registration) _could_ be dynamically linked (modular) ... costs
1879 * include needing to have boardinfo data structures be much more public.
1881 postcore_initcall(spi_init);