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);
243 struct spi_device *spi = to_spi_device(dev);
246 acpi_dev_pm_attach(&spi->dev, true);
247 ret = sdrv->probe(spi);
249 acpi_dev_pm_detach(&spi->dev, true);
254 static int spi_drv_remove(struct device *dev)
256 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
257 struct spi_device *spi = to_spi_device(dev);
260 ret = sdrv->remove(spi);
261 acpi_dev_pm_detach(&spi->dev, true);
266 static void spi_drv_shutdown(struct device *dev)
268 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
270 sdrv->shutdown(to_spi_device(dev));
274 * spi_register_driver - register a SPI driver
275 * @sdrv: the driver to register
278 int spi_register_driver(struct spi_driver *sdrv)
280 sdrv->driver.bus = &spi_bus_type;
282 sdrv->driver.probe = spi_drv_probe;
284 sdrv->driver.remove = spi_drv_remove;
286 sdrv->driver.shutdown = spi_drv_shutdown;
287 return driver_register(&sdrv->driver);
289 EXPORT_SYMBOL_GPL(spi_register_driver);
291 /*-------------------------------------------------------------------------*/
293 /* SPI devices should normally not be created by SPI device drivers; that
294 * would make them board-specific. Similarly with SPI master drivers.
295 * Device registration normally goes into like arch/.../mach.../board-YYY.c
296 * with other readonly (flashable) information about mainboard devices.
300 struct list_head list;
301 struct spi_board_info board_info;
304 static LIST_HEAD(board_list);
305 static LIST_HEAD(spi_master_list);
308 * Used to protect add/del opertion for board_info list and
309 * spi_master list, and their matching process
311 static DEFINE_MUTEX(board_lock);
314 * spi_alloc_device - Allocate a new SPI device
315 * @master: Controller to which device is connected
318 * Allows a driver to allocate and initialize a spi_device without
319 * registering it immediately. This allows a driver to directly
320 * fill the spi_device with device parameters before calling
321 * spi_add_device() on it.
323 * Caller is responsible to call spi_add_device() on the returned
324 * spi_device structure to add it to the SPI master. If the caller
325 * needs to discard the spi_device without adding it, then it should
326 * call spi_dev_put() on it.
328 * Returns a pointer to the new device, or NULL.
330 struct spi_device *spi_alloc_device(struct spi_master *master)
332 struct spi_device *spi;
333 struct device *dev = master->dev.parent;
335 if (!spi_master_get(master))
338 spi = kzalloc(sizeof *spi, GFP_KERNEL);
340 dev_err(dev, "cannot alloc spi_device\n");
341 spi_master_put(master);
345 spi->master = master;
346 spi->dev.parent = &master->dev;
347 spi->dev.bus = &spi_bus_type;
348 spi->dev.release = spidev_release;
349 spi->cs_gpio = -ENOENT;
350 device_initialize(&spi->dev);
353 EXPORT_SYMBOL_GPL(spi_alloc_device);
356 * spi_add_device - Add spi_device allocated with spi_alloc_device
357 * @spi: spi_device to register
359 * Companion function to spi_alloc_device. Devices allocated with
360 * spi_alloc_device can be added onto the spi bus with this function.
362 * Returns 0 on success; negative errno on failure
364 int spi_add_device(struct spi_device *spi)
366 static DEFINE_MUTEX(spi_add_lock);
367 struct spi_master *master = spi->master;
368 struct device *dev = master->dev.parent;
372 /* Chipselects are numbered 0..max; validate. */
373 if (spi->chip_select >= master->num_chipselect) {
374 dev_err(dev, "cs%d >= max %d\n",
376 master->num_chipselect);
380 /* Set the bus ID string */
381 dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
385 /* We need to make sure there's no other device with this
386 * chipselect **BEFORE** we call setup(), else we'll trash
387 * its configuration. Lock against concurrent add() calls.
389 mutex_lock(&spi_add_lock);
391 d = bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));
393 dev_err(dev, "chipselect %d already in use\n",
400 if (master->cs_gpios)
401 spi->cs_gpio = master->cs_gpios[spi->chip_select];
403 /* Drivers may modify this initial i/o setup, but will
404 * normally rely on the device being setup. Devices
405 * using SPI_CS_HIGH can't coexist well otherwise...
407 status = spi_setup(spi);
409 dev_err(dev, "can't setup %s, status %d\n",
410 dev_name(&spi->dev), status);
414 /* Device may be bound to an active driver when this returns */
415 status = device_add(&spi->dev);
417 dev_err(dev, "can't add %s, status %d\n",
418 dev_name(&spi->dev), status);
420 dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
423 mutex_unlock(&spi_add_lock);
426 EXPORT_SYMBOL_GPL(spi_add_device);
429 * spi_new_device - instantiate one new SPI device
430 * @master: Controller to which device is connected
431 * @chip: Describes the SPI device
434 * On typical mainboards, this is purely internal; and it's not needed
435 * after board init creates the hard-wired devices. Some development
436 * platforms may not be able to use spi_register_board_info though, and
437 * this is exported so that for example a USB or parport based adapter
438 * driver could add devices (which it would learn about out-of-band).
440 * Returns the new device, or NULL.
442 struct spi_device *spi_new_device(struct spi_master *master,
443 struct spi_board_info *chip)
445 struct spi_device *proxy;
448 /* NOTE: caller did any chip->bus_num checks necessary.
450 * Also, unless we change the return value convention to use
451 * error-or-pointer (not NULL-or-pointer), troubleshootability
452 * suggests syslogged diagnostics are best here (ugh).
455 proxy = spi_alloc_device(master);
459 WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
461 proxy->chip_select = chip->chip_select;
462 proxy->max_speed_hz = chip->max_speed_hz;
463 proxy->mode = chip->mode;
464 proxy->irq = chip->irq;
465 strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
466 proxy->dev.platform_data = (void *) chip->platform_data;
467 proxy->controller_data = chip->controller_data;
468 proxy->controller_state = NULL;
470 status = spi_add_device(proxy);
478 EXPORT_SYMBOL_GPL(spi_new_device);
480 static void spi_match_master_to_boardinfo(struct spi_master *master,
481 struct spi_board_info *bi)
483 struct spi_device *dev;
485 if (master->bus_num != bi->bus_num)
488 dev = spi_new_device(master, bi);
490 dev_err(master->dev.parent, "can't create new device for %s\n",
495 * spi_register_board_info - register SPI devices for a given board
496 * @info: array of chip descriptors
497 * @n: how many descriptors are provided
500 * Board-specific early init code calls this (probably during arch_initcall)
501 * with segments of the SPI device table. Any device nodes are created later,
502 * after the relevant parent SPI controller (bus_num) is defined. We keep
503 * this table of devices forever, so that reloading a controller driver will
504 * not make Linux forget about these hard-wired devices.
506 * Other code can also call this, e.g. a particular add-on board might provide
507 * SPI devices through its expansion connector, so code initializing that board
508 * would naturally declare its SPI devices.
510 * The board info passed can safely be __initdata ... but be careful of
511 * any embedded pointers (platform_data, etc), they're copied as-is.
513 int spi_register_board_info(struct spi_board_info const *info, unsigned n)
515 struct boardinfo *bi;
518 bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
522 for (i = 0; i < n; i++, bi++, info++) {
523 struct spi_master *master;
525 memcpy(&bi->board_info, info, sizeof(*info));
526 mutex_lock(&board_lock);
527 list_add_tail(&bi->list, &board_list);
528 list_for_each_entry(master, &spi_master_list, list)
529 spi_match_master_to_boardinfo(master, &bi->board_info);
530 mutex_unlock(&board_lock);
536 /*-------------------------------------------------------------------------*/
539 * spi_pump_messages - kthread work function which processes spi message queue
540 * @work: pointer to kthread work struct contained in the master struct
542 * This function checks if there is any spi message in the queue that
543 * needs processing and if so call out to the driver to initialize hardware
544 * and transfer each message.
547 static void spi_pump_messages(struct kthread_work *work)
549 struct spi_master *master =
550 container_of(work, struct spi_master, pump_messages);
552 bool was_busy = false;
555 /* Lock queue and check for queue work */
556 spin_lock_irqsave(&master->queue_lock, flags);
557 if (list_empty(&master->queue) || !master->running) {
559 spin_unlock_irqrestore(&master->queue_lock, flags);
562 master->busy = false;
563 spin_unlock_irqrestore(&master->queue_lock, flags);
564 if (master->unprepare_transfer_hardware &&
565 master->unprepare_transfer_hardware(master))
566 dev_err(&master->dev,
567 "failed to unprepare transfer hardware\n");
568 if (master->auto_runtime_pm) {
569 pm_runtime_mark_last_busy(master->dev.parent);
570 pm_runtime_put_autosuspend(master->dev.parent);
575 /* Make sure we are not already running a message */
576 if (master->cur_msg) {
577 spin_unlock_irqrestore(&master->queue_lock, flags);
580 /* Extract head of queue */
582 list_entry(master->queue.next, struct spi_message, queue);
584 list_del_init(&master->cur_msg->queue);
589 spin_unlock_irqrestore(&master->queue_lock, flags);
591 if (!was_busy && master->auto_runtime_pm) {
592 ret = pm_runtime_get_sync(master->dev.parent);
594 dev_err(&master->dev, "Failed to power device: %d\n",
600 if (!was_busy && master->prepare_transfer_hardware) {
601 ret = master->prepare_transfer_hardware(master);
603 dev_err(&master->dev,
604 "failed to prepare transfer hardware\n");
606 if (master->auto_runtime_pm)
607 pm_runtime_put(master->dev.parent);
612 ret = master->transfer_one_message(master, master->cur_msg);
614 dev_err(&master->dev,
615 "failed to transfer one message from queue\n");
620 static int spi_init_queue(struct spi_master *master)
622 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
624 INIT_LIST_HEAD(&master->queue);
625 spin_lock_init(&master->queue_lock);
627 master->running = false;
628 master->busy = false;
630 init_kthread_worker(&master->kworker);
631 master->kworker_task = kthread_run(kthread_worker_fn,
632 &master->kworker, "%s",
633 dev_name(&master->dev));
634 if (IS_ERR(master->kworker_task)) {
635 dev_err(&master->dev, "failed to create message pump task\n");
638 init_kthread_work(&master->pump_messages, spi_pump_messages);
641 * Master config will indicate if this controller should run the
642 * message pump with high (realtime) priority to reduce the transfer
643 * latency on the bus by minimising the delay between a transfer
644 * request and the scheduling of the message pump thread. Without this
645 * setting the message pump thread will remain at default priority.
648 dev_info(&master->dev,
649 "will run message pump with realtime priority\n");
650 sched_setscheduler(master->kworker_task, SCHED_FIFO, ¶m);
657 * spi_get_next_queued_message() - called by driver to check for queued
659 * @master: the master to check for queued messages
661 * If there are more messages in the queue, the next message is returned from
664 struct spi_message *spi_get_next_queued_message(struct spi_master *master)
666 struct spi_message *next;
669 /* get a pointer to the next message, if any */
670 spin_lock_irqsave(&master->queue_lock, flags);
671 if (list_empty(&master->queue))
674 next = list_entry(master->queue.next,
675 struct spi_message, queue);
676 spin_unlock_irqrestore(&master->queue_lock, flags);
680 EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
683 * spi_finalize_current_message() - the current message is complete
684 * @master: the master to return the message to
686 * Called by the driver to notify the core that the message in the front of the
687 * queue is complete and can be removed from the queue.
689 void spi_finalize_current_message(struct spi_master *master)
691 struct spi_message *mesg;
694 spin_lock_irqsave(&master->queue_lock, flags);
695 mesg = master->cur_msg;
696 master->cur_msg = NULL;
698 queue_kthread_work(&master->kworker, &master->pump_messages);
699 spin_unlock_irqrestore(&master->queue_lock, flags);
703 mesg->complete(mesg->context);
705 EXPORT_SYMBOL_GPL(spi_finalize_current_message);
707 static int spi_start_queue(struct spi_master *master)
711 spin_lock_irqsave(&master->queue_lock, flags);
713 if (master->running || master->busy) {
714 spin_unlock_irqrestore(&master->queue_lock, flags);
718 master->running = true;
719 master->cur_msg = NULL;
720 spin_unlock_irqrestore(&master->queue_lock, flags);
722 queue_kthread_work(&master->kworker, &master->pump_messages);
727 static int spi_stop_queue(struct spi_master *master)
730 unsigned limit = 500;
733 spin_lock_irqsave(&master->queue_lock, flags);
736 * This is a bit lame, but is optimized for the common execution path.
737 * A wait_queue on the master->busy could be used, but then the common
738 * execution path (pump_messages) would be required to call wake_up or
739 * friends on every SPI message. Do this instead.
741 while ((!list_empty(&master->queue) || master->busy) && limit--) {
742 spin_unlock_irqrestore(&master->queue_lock, flags);
744 spin_lock_irqsave(&master->queue_lock, flags);
747 if (!list_empty(&master->queue) || master->busy)
750 master->running = false;
752 spin_unlock_irqrestore(&master->queue_lock, flags);
755 dev_warn(&master->dev,
756 "could not stop message queue\n");
762 static int spi_destroy_queue(struct spi_master *master)
766 ret = spi_stop_queue(master);
769 * flush_kthread_worker will block until all work is done.
770 * If the reason that stop_queue timed out is that the work will never
771 * finish, then it does no good to call flush/stop thread, so
775 dev_err(&master->dev, "problem destroying queue\n");
779 flush_kthread_worker(&master->kworker);
780 kthread_stop(master->kworker_task);
786 * spi_queued_transfer - transfer function for queued transfers
787 * @spi: spi device which is requesting transfer
788 * @msg: spi message which is to handled is queued to driver queue
790 static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
792 struct spi_master *master = spi->master;
795 spin_lock_irqsave(&master->queue_lock, flags);
797 if (!master->running) {
798 spin_unlock_irqrestore(&master->queue_lock, flags);
801 msg->actual_length = 0;
802 msg->status = -EINPROGRESS;
804 list_add_tail(&msg->queue, &master->queue);
806 queue_kthread_work(&master->kworker, &master->pump_messages);
808 spin_unlock_irqrestore(&master->queue_lock, flags);
812 static int spi_master_initialize_queue(struct spi_master *master)
816 master->queued = true;
817 master->transfer = spi_queued_transfer;
819 /* Initialize and start queue */
820 ret = spi_init_queue(master);
822 dev_err(&master->dev, "problem initializing queue\n");
825 ret = spi_start_queue(master);
827 dev_err(&master->dev, "problem starting queue\n");
828 goto err_start_queue;
835 spi_destroy_queue(master);
839 /*-------------------------------------------------------------------------*/
841 #if defined(CONFIG_OF)
843 * of_register_spi_devices() - Register child devices onto the SPI bus
844 * @master: Pointer to spi_master device
846 * Registers an spi_device for each child node of master node which has a 'reg'
849 static void of_register_spi_devices(struct spi_master *master)
851 struct spi_device *spi;
852 struct device_node *nc;
854 char modalias[SPI_NAME_SIZE + 4];
858 if (!master->dev.of_node)
861 for_each_available_child_of_node(master->dev.of_node, nc) {
862 /* Alloc an spi_device */
863 spi = spi_alloc_device(master);
865 dev_err(&master->dev, "spi_device alloc error for %s\n",
871 /* Select device driver */
872 if (of_modalias_node(nc, spi->modalias,
873 sizeof(spi->modalias)) < 0) {
874 dev_err(&master->dev, "cannot find modalias for %s\n",
881 prop = of_get_property(nc, "reg", &len);
882 if (!prop || len < sizeof(*prop)) {
883 dev_err(&master->dev, "%s has no 'reg' property\n",
888 spi->chip_select = be32_to_cpup(prop);
890 /* Mode (clock phase/polarity/etc.) */
891 if (of_find_property(nc, "spi-cpha", NULL))
892 spi->mode |= SPI_CPHA;
893 if (of_find_property(nc, "spi-cpol", NULL))
894 spi->mode |= SPI_CPOL;
895 if (of_find_property(nc, "spi-cs-high", NULL))
896 spi->mode |= SPI_CS_HIGH;
897 if (of_find_property(nc, "spi-3wire", NULL))
898 spi->mode |= SPI_3WIRE;
900 /* Device DUAL/QUAD mode */
901 prop = of_get_property(nc, "spi-tx-bus-width", &len);
902 if (prop && len == sizeof(*prop)) {
903 switch (be32_to_cpup(prop)) {
904 case SPI_NBITS_SINGLE:
907 spi->mode |= SPI_TX_DUAL;
910 spi->mode |= SPI_TX_QUAD;
913 dev_err(&master->dev,
914 "spi-tx-bus-width %d not supported\n",
921 prop = of_get_property(nc, "spi-rx-bus-width", &len);
922 if (prop && len == sizeof(*prop)) {
923 switch (be32_to_cpup(prop)) {
924 case SPI_NBITS_SINGLE:
927 spi->mode |= SPI_RX_DUAL;
930 spi->mode |= SPI_RX_QUAD;
933 dev_err(&master->dev,
934 "spi-rx-bus-width %d not supported\n",
942 prop = of_get_property(nc, "spi-max-frequency", &len);
943 if (!prop || len < sizeof(*prop)) {
944 dev_err(&master->dev, "%s has no 'spi-max-frequency' property\n",
949 spi->max_speed_hz = be32_to_cpup(prop);
952 spi->irq = irq_of_parse_and_map(nc, 0);
954 /* Store a pointer to the node in the device structure */
956 spi->dev.of_node = nc;
958 /* Register the new device */
959 snprintf(modalias, sizeof(modalias), "%s%s", SPI_MODULE_PREFIX,
961 request_module(modalias);
962 rc = spi_add_device(spi);
964 dev_err(&master->dev, "spi_device register error %s\n",
972 static void of_register_spi_devices(struct spi_master *master) { }
976 static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
978 struct spi_device *spi = data;
980 if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
981 struct acpi_resource_spi_serialbus *sb;
983 sb = &ares->data.spi_serial_bus;
984 if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
985 spi->chip_select = sb->device_selection;
986 spi->max_speed_hz = sb->connection_speed;
988 if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
989 spi->mode |= SPI_CPHA;
990 if (sb->clock_polarity == ACPI_SPI_START_HIGH)
991 spi->mode |= SPI_CPOL;
992 if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
993 spi->mode |= SPI_CS_HIGH;
995 } else if (spi->irq < 0) {
998 if (acpi_dev_resource_interrupt(ares, 0, &r))
1002 /* Always tell the ACPI core to skip this resource */
1006 static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
1007 void *data, void **return_value)
1009 struct spi_master *master = data;
1010 struct list_head resource_list;
1011 struct acpi_device *adev;
1012 struct spi_device *spi;
1015 if (acpi_bus_get_device(handle, &adev))
1017 if (acpi_bus_get_status(adev) || !adev->status.present)
1020 spi = spi_alloc_device(master);
1022 dev_err(&master->dev, "failed to allocate SPI device for %s\n",
1023 dev_name(&adev->dev));
1024 return AE_NO_MEMORY;
1027 ACPI_HANDLE_SET(&spi->dev, handle);
1030 INIT_LIST_HEAD(&resource_list);
1031 ret = acpi_dev_get_resources(adev, &resource_list,
1032 acpi_spi_add_resource, spi);
1033 acpi_dev_free_resource_list(&resource_list);
1035 if (ret < 0 || !spi->max_speed_hz) {
1040 adev->power.flags.ignore_parent = true;
1041 strlcpy(spi->modalias, dev_name(&adev->dev), sizeof(spi->modalias));
1042 if (spi_add_device(spi)) {
1043 adev->power.flags.ignore_parent = false;
1044 dev_err(&master->dev, "failed to add SPI device %s from ACPI\n",
1045 dev_name(&adev->dev));
1052 static void acpi_register_spi_devices(struct spi_master *master)
1057 handle = ACPI_HANDLE(master->dev.parent);
1061 status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
1062 acpi_spi_add_device, NULL,
1064 if (ACPI_FAILURE(status))
1065 dev_warn(&master->dev, "failed to enumerate SPI slaves\n");
1068 static inline void acpi_register_spi_devices(struct spi_master *master) {}
1069 #endif /* CONFIG_ACPI */
1071 static void spi_master_release(struct device *dev)
1073 struct spi_master *master;
1075 master = container_of(dev, struct spi_master, dev);
1079 static struct class spi_master_class = {
1080 .name = "spi_master",
1081 .owner = THIS_MODULE,
1082 .dev_release = spi_master_release,
1088 * spi_alloc_master - allocate SPI master controller
1089 * @dev: the controller, possibly using the platform_bus
1090 * @size: how much zeroed driver-private data to allocate; the pointer to this
1091 * memory is in the driver_data field of the returned device,
1092 * accessible with spi_master_get_devdata().
1093 * Context: can sleep
1095 * This call is used only by SPI master controller drivers, which are the
1096 * only ones directly touching chip registers. It's how they allocate
1097 * an spi_master structure, prior to calling spi_register_master().
1099 * This must be called from context that can sleep. It returns the SPI
1100 * master structure on success, else NULL.
1102 * The caller is responsible for assigning the bus number and initializing
1103 * the master's methods before calling spi_register_master(); and (after errors
1104 * adding the device) calling spi_master_put() and kfree() to prevent a memory
1107 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
1109 struct spi_master *master;
1114 master = kzalloc(size + sizeof *master, GFP_KERNEL);
1118 device_initialize(&master->dev);
1119 master->bus_num = -1;
1120 master->num_chipselect = 1;
1121 master->dev.class = &spi_master_class;
1122 master->dev.parent = get_device(dev);
1123 spi_master_set_devdata(master, &master[1]);
1127 EXPORT_SYMBOL_GPL(spi_alloc_master);
1130 static int of_spi_register_master(struct spi_master *master)
1133 struct device_node *np = master->dev.of_node;
1138 nb = of_gpio_named_count(np, "cs-gpios");
1139 master->num_chipselect = max(nb, (int)master->num_chipselect);
1141 /* Return error only for an incorrectly formed cs-gpios property */
1142 if (nb == 0 || nb == -ENOENT)
1147 cs = devm_kzalloc(&master->dev,
1148 sizeof(int) * master->num_chipselect,
1150 master->cs_gpios = cs;
1152 if (!master->cs_gpios)
1155 for (i = 0; i < master->num_chipselect; i++)
1158 for (i = 0; i < nb; i++)
1159 cs[i] = of_get_named_gpio(np, "cs-gpios", i);
1164 static int of_spi_register_master(struct spi_master *master)
1171 * spi_register_master - register SPI master controller
1172 * @master: initialized master, originally from spi_alloc_master()
1173 * Context: can sleep
1175 * SPI master controllers connect to their drivers using some non-SPI bus,
1176 * such as the platform bus. The final stage of probe() in that code
1177 * includes calling spi_register_master() to hook up to this SPI bus glue.
1179 * SPI controllers use board specific (often SOC specific) bus numbers,
1180 * and board-specific addressing for SPI devices combines those numbers
1181 * with chip select numbers. Since SPI does not directly support dynamic
1182 * device identification, boards need configuration tables telling which
1183 * chip is at which address.
1185 * This must be called from context that can sleep. It returns zero on
1186 * success, else a negative error code (dropping the master's refcount).
1187 * After a successful return, the caller is responsible for calling
1188 * spi_unregister_master().
1190 int spi_register_master(struct spi_master *master)
1192 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
1193 struct device *dev = master->dev.parent;
1194 struct boardinfo *bi;
1195 int status = -ENODEV;
1201 status = of_spi_register_master(master);
1205 /* even if it's just one always-selected device, there must
1206 * be at least one chipselect
1208 if (master->num_chipselect == 0)
1211 if ((master->bus_num < 0) && master->dev.of_node)
1212 master->bus_num = of_alias_get_id(master->dev.of_node, "spi");
1214 /* convention: dynamically assigned bus IDs count down from the max */
1215 if (master->bus_num < 0) {
1216 /* FIXME switch to an IDR based scheme, something like
1217 * I2C now uses, so we can't run out of "dynamic" IDs
1219 master->bus_num = atomic_dec_return(&dyn_bus_id);
1223 spin_lock_init(&master->bus_lock_spinlock);
1224 mutex_init(&master->bus_lock_mutex);
1225 master->bus_lock_flag = 0;
1227 /* register the device, then userspace will see it.
1228 * registration fails if the bus ID is in use.
1230 dev_set_name(&master->dev, "spi%u", master->bus_num);
1231 status = device_add(&master->dev);
1234 dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
1235 dynamic ? " (dynamic)" : "");
1237 /* If we're using a queued driver, start the queue */
1238 if (master->transfer)
1239 dev_info(dev, "master is unqueued, this is deprecated\n");
1241 status = spi_master_initialize_queue(master);
1243 device_del(&master->dev);
1248 mutex_lock(&board_lock);
1249 list_add_tail(&master->list, &spi_master_list);
1250 list_for_each_entry(bi, &board_list, list)
1251 spi_match_master_to_boardinfo(master, &bi->board_info);
1252 mutex_unlock(&board_lock);
1254 /* Register devices from the device tree and ACPI */
1255 of_register_spi_devices(master);
1256 acpi_register_spi_devices(master);
1260 EXPORT_SYMBOL_GPL(spi_register_master);
1262 static int __unregister(struct device *dev, void *null)
1264 spi_unregister_device(to_spi_device(dev));
1269 * spi_unregister_master - unregister SPI master controller
1270 * @master: the master being unregistered
1271 * Context: can sleep
1273 * This call is used only by SPI master controller drivers, which are the
1274 * only ones directly touching chip registers.
1276 * This must be called from context that can sleep.
1278 void spi_unregister_master(struct spi_master *master)
1282 if (master->queued) {
1283 if (spi_destroy_queue(master))
1284 dev_err(&master->dev, "queue remove failed\n");
1287 mutex_lock(&board_lock);
1288 list_del(&master->list);
1289 mutex_unlock(&board_lock);
1291 dummy = device_for_each_child(&master->dev, NULL, __unregister);
1292 device_unregister(&master->dev);
1294 EXPORT_SYMBOL_GPL(spi_unregister_master);
1296 int spi_master_suspend(struct spi_master *master)
1300 /* Basically no-ops for non-queued masters */
1301 if (!master->queued)
1304 ret = spi_stop_queue(master);
1306 dev_err(&master->dev, "queue stop failed\n");
1310 EXPORT_SYMBOL_GPL(spi_master_suspend);
1312 int spi_master_resume(struct spi_master *master)
1316 if (!master->queued)
1319 ret = spi_start_queue(master);
1321 dev_err(&master->dev, "queue restart failed\n");
1325 EXPORT_SYMBOL_GPL(spi_master_resume);
1327 static int __spi_master_match(struct device *dev, const void *data)
1329 struct spi_master *m;
1330 const u16 *bus_num = data;
1332 m = container_of(dev, struct spi_master, dev);
1333 return m->bus_num == *bus_num;
1337 * spi_busnum_to_master - look up master associated with bus_num
1338 * @bus_num: the master's bus number
1339 * Context: can sleep
1341 * This call may be used with devices that are registered after
1342 * arch init time. It returns a refcounted pointer to the relevant
1343 * spi_master (which the caller must release), or NULL if there is
1344 * no such master registered.
1346 struct spi_master *spi_busnum_to_master(u16 bus_num)
1349 struct spi_master *master = NULL;
1351 dev = class_find_device(&spi_master_class, NULL, &bus_num,
1352 __spi_master_match);
1354 master = container_of(dev, struct spi_master, dev);
1355 /* reference got in class_find_device */
1358 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
1361 /*-------------------------------------------------------------------------*/
1363 /* Core methods for SPI master protocol drivers. Some of the
1364 * other core methods are currently defined as inline functions.
1368 * spi_setup - setup SPI mode and clock rate
1369 * @spi: the device whose settings are being modified
1370 * Context: can sleep, and no requests are queued to the device
1372 * SPI protocol drivers may need to update the transfer mode if the
1373 * device doesn't work with its default. They may likewise need
1374 * to update clock rates or word sizes from initial values. This function
1375 * changes those settings, and must be called from a context that can sleep.
1376 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
1377 * effect the next time the device is selected and data is transferred to
1378 * or from it. When this function returns, the spi device is deselected.
1380 * Note that this call will fail if the protocol driver specifies an option
1381 * that the underlying controller or its driver does not support. For
1382 * example, not all hardware supports wire transfers using nine bit words,
1383 * LSB-first wire encoding, or active-high chipselects.
1385 int spi_setup(struct spi_device *spi)
1390 /* check mode to prevent that DUAL and QUAD set at the same time
1392 if (((spi->mode & SPI_TX_DUAL) && (spi->mode & SPI_TX_QUAD)) ||
1393 ((spi->mode & SPI_RX_DUAL) && (spi->mode & SPI_RX_QUAD))) {
1395 "setup: can not select dual and quad at the same time\n");
1398 /* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
1400 if ((spi->mode & SPI_3WIRE) && (spi->mode &
1401 (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)))
1403 /* help drivers fail *cleanly* when they need options
1404 * that aren't supported with their current master
1406 bad_bits = spi->mode & ~spi->master->mode_bits;
1408 dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
1413 if (!spi->bits_per_word)
1414 spi->bits_per_word = 8;
1416 if (spi->master->setup)
1417 status = spi->master->setup(spi);
1419 dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
1420 "%u bits/w, %u Hz max --> %d\n",
1421 (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
1422 (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
1423 (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
1424 (spi->mode & SPI_3WIRE) ? "3wire, " : "",
1425 (spi->mode & SPI_LOOP) ? "loopback, " : "",
1426 spi->bits_per_word, spi->max_speed_hz,
1431 EXPORT_SYMBOL_GPL(spi_setup);
1433 static int __spi_async(struct spi_device *spi, struct spi_message *message)
1435 struct spi_master *master = spi->master;
1436 struct spi_transfer *xfer;
1438 if (list_empty(&message->transfers))
1440 if (!message->complete)
1443 /* Half-duplex links include original MicroWire, and ones with
1444 * only one data pin like SPI_3WIRE (switches direction) or where
1445 * either MOSI or MISO is missing. They can also be caused by
1446 * software limitations.
1448 if ((master->flags & SPI_MASTER_HALF_DUPLEX)
1449 || (spi->mode & SPI_3WIRE)) {
1450 unsigned flags = master->flags;
1452 list_for_each_entry(xfer, &message->transfers, transfer_list) {
1453 if (xfer->rx_buf && xfer->tx_buf)
1455 if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
1457 if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
1463 * Set transfer bits_per_word and max speed as spi device default if
1464 * it is not set for this transfer.
1465 * Set transfer tx_nbits and rx_nbits as single transfer default
1466 * (SPI_NBITS_SINGLE) if it is not set for this transfer.
1468 list_for_each_entry(xfer, &message->transfers, transfer_list) {
1469 message->frame_length += xfer->len;
1470 if (!xfer->bits_per_word)
1471 xfer->bits_per_word = spi->bits_per_word;
1472 if (!xfer->speed_hz) {
1473 xfer->speed_hz = spi->max_speed_hz;
1474 if (master->max_speed_hz &&
1475 xfer->speed_hz > master->max_speed_hz)
1476 xfer->speed_hz = master->max_speed_hz;
1479 if (master->bits_per_word_mask) {
1480 /* Only 32 bits fit in the mask */
1481 if (xfer->bits_per_word > 32)
1483 if (!(master->bits_per_word_mask &
1484 BIT(xfer->bits_per_word - 1)))
1488 if (xfer->speed_hz && master->min_speed_hz &&
1489 xfer->speed_hz < master->min_speed_hz)
1491 if (xfer->speed_hz && master->max_speed_hz &&
1492 xfer->speed_hz > master->max_speed_hz)
1495 if (xfer->tx_buf && !xfer->tx_nbits)
1496 xfer->tx_nbits = SPI_NBITS_SINGLE;
1497 if (xfer->rx_buf && !xfer->rx_nbits)
1498 xfer->rx_nbits = SPI_NBITS_SINGLE;
1499 /* check transfer tx/rx_nbits:
1500 * 1. keep the value is not out of single, dual and quad
1501 * 2. keep tx/rx_nbits is contained by mode in spi_device
1502 * 3. if SPI_3WIRE, tx/rx_nbits should be in single
1505 if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
1506 xfer->tx_nbits != SPI_NBITS_DUAL &&
1507 xfer->tx_nbits != SPI_NBITS_QUAD)
1509 if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
1510 !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
1512 if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
1513 !(spi->mode & SPI_TX_QUAD))
1515 if ((spi->mode & SPI_3WIRE) &&
1516 (xfer->tx_nbits != SPI_NBITS_SINGLE))
1519 /* check transfer rx_nbits */
1521 if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
1522 xfer->rx_nbits != SPI_NBITS_DUAL &&
1523 xfer->rx_nbits != SPI_NBITS_QUAD)
1525 if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
1526 !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
1528 if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
1529 !(spi->mode & SPI_RX_QUAD))
1531 if ((spi->mode & SPI_3WIRE) &&
1532 (xfer->rx_nbits != SPI_NBITS_SINGLE))
1538 message->status = -EINPROGRESS;
1539 return master->transfer(spi, message);
1543 * spi_async - asynchronous SPI transfer
1544 * @spi: device with which data will be exchanged
1545 * @message: describes the data transfers, including completion callback
1546 * Context: any (irqs may be blocked, etc)
1548 * This call may be used in_irq and other contexts which can't sleep,
1549 * as well as from task contexts which can sleep.
1551 * The completion callback is invoked in a context which can't sleep.
1552 * Before that invocation, the value of message->status is undefined.
1553 * When the callback is issued, message->status holds either zero (to
1554 * indicate complete success) or a negative error code. After that
1555 * callback returns, the driver which issued the transfer request may
1556 * deallocate the associated memory; it's no longer in use by any SPI
1557 * core or controller driver code.
1559 * Note that although all messages to a spi_device are handled in
1560 * FIFO order, messages may go to different devices in other orders.
1561 * Some device might be higher priority, or have various "hard" access
1562 * time requirements, for example.
1564 * On detection of any fault during the transfer, processing of
1565 * the entire message is aborted, and the device is deselected.
1566 * Until returning from the associated message completion callback,
1567 * no other spi_message queued to that device will be processed.
1568 * (This rule applies equally to all the synchronous transfer calls,
1569 * which are wrappers around this core asynchronous primitive.)
1571 int spi_async(struct spi_device *spi, struct spi_message *message)
1573 struct spi_master *master = spi->master;
1575 unsigned long flags;
1577 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1579 if (master->bus_lock_flag)
1582 ret = __spi_async(spi, message);
1584 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1588 EXPORT_SYMBOL_GPL(spi_async);
1591 * spi_async_locked - version of spi_async with exclusive bus usage
1592 * @spi: device with which data will be exchanged
1593 * @message: describes the data transfers, including completion callback
1594 * Context: any (irqs may be blocked, etc)
1596 * This call may be used in_irq and other contexts which can't sleep,
1597 * as well as from task contexts which can sleep.
1599 * The completion callback is invoked in a context which can't sleep.
1600 * Before that invocation, the value of message->status is undefined.
1601 * When the callback is issued, message->status holds either zero (to
1602 * indicate complete success) or a negative error code. After that
1603 * callback returns, the driver which issued the transfer request may
1604 * deallocate the associated memory; it's no longer in use by any SPI
1605 * core or controller driver code.
1607 * Note that although all messages to a spi_device are handled in
1608 * FIFO order, messages may go to different devices in other orders.
1609 * Some device might be higher priority, or have various "hard" access
1610 * time requirements, for example.
1612 * On detection of any fault during the transfer, processing of
1613 * the entire message is aborted, and the device is deselected.
1614 * Until returning from the associated message completion callback,
1615 * no other spi_message queued to that device will be processed.
1616 * (This rule applies equally to all the synchronous transfer calls,
1617 * which are wrappers around this core asynchronous primitive.)
1619 int spi_async_locked(struct spi_device *spi, struct spi_message *message)
1621 struct spi_master *master = spi->master;
1623 unsigned long flags;
1625 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1627 ret = __spi_async(spi, message);
1629 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1634 EXPORT_SYMBOL_GPL(spi_async_locked);
1637 /*-------------------------------------------------------------------------*/
1639 /* Utility methods for SPI master protocol drivers, layered on
1640 * top of the core. Some other utility methods are defined as
1644 static void spi_complete(void *arg)
1649 static int __spi_sync(struct spi_device *spi, struct spi_message *message,
1652 DECLARE_COMPLETION_ONSTACK(done);
1654 struct spi_master *master = spi->master;
1656 message->complete = spi_complete;
1657 message->context = &done;
1660 mutex_lock(&master->bus_lock_mutex);
1662 status = spi_async_locked(spi, message);
1665 mutex_unlock(&master->bus_lock_mutex);
1668 wait_for_completion(&done);
1669 status = message->status;
1671 message->context = NULL;
1676 * spi_sync - blocking/synchronous SPI data transfers
1677 * @spi: device with which data will be exchanged
1678 * @message: describes the data transfers
1679 * Context: can sleep
1681 * This call may only be used from a context that may sleep. The sleep
1682 * is non-interruptible, and has no timeout. Low-overhead controller
1683 * drivers may DMA directly into and out of the message buffers.
1685 * Note that the SPI device's chip select is active during the message,
1686 * and then is normally disabled between messages. Drivers for some
1687 * frequently-used devices may want to minimize costs of selecting a chip,
1688 * by leaving it selected in anticipation that the next message will go
1689 * to the same chip. (That may increase power usage.)
1691 * Also, the caller is guaranteeing that the memory associated with the
1692 * message will not be freed before this call returns.
1694 * It returns zero on success, else a negative error code.
1696 int spi_sync(struct spi_device *spi, struct spi_message *message)
1698 return __spi_sync(spi, message, 0);
1700 EXPORT_SYMBOL_GPL(spi_sync);
1703 * spi_sync_locked - version of spi_sync with exclusive bus usage
1704 * @spi: device with which data will be exchanged
1705 * @message: describes the data transfers
1706 * Context: can sleep
1708 * This call may only be used from a context that may sleep. The sleep
1709 * is non-interruptible, and has no timeout. Low-overhead controller
1710 * drivers may DMA directly into and out of the message buffers.
1712 * This call should be used by drivers that require exclusive access to the
1713 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
1714 * be released by a spi_bus_unlock call when the exclusive access is over.
1716 * It returns zero on success, else a negative error code.
1718 int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
1720 return __spi_sync(spi, message, 1);
1722 EXPORT_SYMBOL_GPL(spi_sync_locked);
1725 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
1726 * @master: SPI bus master that should be locked for exclusive bus access
1727 * Context: can sleep
1729 * This call may only be used from a context that may sleep. The sleep
1730 * is non-interruptible, and has no timeout.
1732 * This call should be used by drivers that require exclusive access to the
1733 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
1734 * exclusive access is over. Data transfer must be done by spi_sync_locked
1735 * and spi_async_locked calls when the SPI bus lock is held.
1737 * It returns zero on success, else a negative error code.
1739 int spi_bus_lock(struct spi_master *master)
1741 unsigned long flags;
1743 mutex_lock(&master->bus_lock_mutex);
1745 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1746 master->bus_lock_flag = 1;
1747 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1749 /* mutex remains locked until spi_bus_unlock is called */
1753 EXPORT_SYMBOL_GPL(spi_bus_lock);
1756 * spi_bus_unlock - release the lock for exclusive SPI bus usage
1757 * @master: SPI bus master that was locked for exclusive bus access
1758 * Context: can sleep
1760 * This call may only be used from a context that may sleep. The sleep
1761 * is non-interruptible, and has no timeout.
1763 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
1766 * It returns zero on success, else a negative error code.
1768 int spi_bus_unlock(struct spi_master *master)
1770 master->bus_lock_flag = 0;
1772 mutex_unlock(&master->bus_lock_mutex);
1776 EXPORT_SYMBOL_GPL(spi_bus_unlock);
1778 /* portable code must never pass more than 32 bytes */
1779 #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
1784 * spi_write_then_read - SPI synchronous write followed by read
1785 * @spi: device with which data will be exchanged
1786 * @txbuf: data to be written (need not be dma-safe)
1787 * @n_tx: size of txbuf, in bytes
1788 * @rxbuf: buffer into which data will be read (need not be dma-safe)
1789 * @n_rx: size of rxbuf, in bytes
1790 * Context: can sleep
1792 * This performs a half duplex MicroWire style transaction with the
1793 * device, sending txbuf and then reading rxbuf. The return value
1794 * is zero for success, else a negative errno status code.
1795 * This call may only be used from a context that may sleep.
1797 * Parameters to this routine are always copied using a small buffer;
1798 * portable code should never use this for more than 32 bytes.
1799 * Performance-sensitive or bulk transfer code should instead use
1800 * spi_{async,sync}() calls with dma-safe buffers.
1802 int spi_write_then_read(struct spi_device *spi,
1803 const void *txbuf, unsigned n_tx,
1804 void *rxbuf, unsigned n_rx)
1806 static DEFINE_MUTEX(lock);
1809 struct spi_message message;
1810 struct spi_transfer x[2];
1813 /* Use preallocated DMA-safe buffer if we can. We can't avoid
1814 * copying here, (as a pure convenience thing), but we can
1815 * keep heap costs out of the hot path unless someone else is
1816 * using the pre-allocated buffer or the transfer is too large.
1818 if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
1819 local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx),
1820 GFP_KERNEL | GFP_DMA);
1827 spi_message_init(&message);
1828 memset(x, 0, sizeof x);
1831 spi_message_add_tail(&x[0], &message);
1835 spi_message_add_tail(&x[1], &message);
1838 memcpy(local_buf, txbuf, n_tx);
1839 x[0].tx_buf = local_buf;
1840 x[1].rx_buf = local_buf + n_tx;
1843 status = spi_sync(spi, &message);
1845 memcpy(rxbuf, x[1].rx_buf, n_rx);
1847 if (x[0].tx_buf == buf)
1848 mutex_unlock(&lock);
1854 EXPORT_SYMBOL_GPL(spi_write_then_read);
1856 /*-------------------------------------------------------------------------*/
1858 static int __init spi_init(void)
1862 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1868 status = bus_register(&spi_bus_type);
1872 status = class_register(&spi_master_class);
1878 bus_unregister(&spi_bus_type);
1886 /* board_info is normally registered in arch_initcall(),
1887 * but even essential drivers wait till later
1889 * REVISIT only boardinfo really needs static linking. the rest (device and
1890 * driver registration) _could_ be dynamically linked (modular) ... costs
1891 * include needing to have boardinfo data structures be much more public.
1893 postcore_initcall(spi_init);