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/dma-mapping.h>
28 #include <linux/dmaengine.h>
29 #include <linux/mutex.h>
30 #include <linux/of_device.h>
31 #include <linux/of_irq.h>
32 #include <linux/slab.h>
33 #include <linux/mod_devicetable.h>
34 #include <linux/spi/spi.h>
35 #include <linux/of_gpio.h>
36 #include <linux/pm_runtime.h>
37 #include <linux/export.h>
38 #include <linux/sched/rt.h>
39 #include <linux/delay.h>
40 #include <linux/kthread.h>
41 #include <linux/ioport.h>
42 #include <linux/acpi.h>
44 #define CREATE_TRACE_POINTS
45 #include <trace/events/spi.h>
47 static void spidev_release(struct device *dev)
49 struct spi_device *spi = to_spi_device(dev);
51 /* spi masters may cleanup for released devices */
52 if (spi->master->cleanup)
53 spi->master->cleanup(spi);
55 spi_master_put(spi->master);
60 modalias_show(struct device *dev, struct device_attribute *a, char *buf)
62 const struct spi_device *spi = to_spi_device(dev);
65 len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
69 return sprintf(buf, "%s%s\n", SPI_MODULE_PREFIX, spi->modalias);
71 static DEVICE_ATTR_RO(modalias);
73 static struct attribute *spi_dev_attrs[] = {
74 &dev_attr_modalias.attr,
77 ATTRIBUTE_GROUPS(spi_dev);
79 /* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
80 * and the sysfs version makes coldplug work too.
83 static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
84 const struct spi_device *sdev)
87 if (!strcmp(sdev->modalias, id->name))
94 const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
96 const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
98 return spi_match_id(sdrv->id_table, sdev);
100 EXPORT_SYMBOL_GPL(spi_get_device_id);
102 static int spi_match_device(struct device *dev, struct device_driver *drv)
104 const struct spi_device *spi = to_spi_device(dev);
105 const struct spi_driver *sdrv = to_spi_driver(drv);
107 /* Attempt an OF style match */
108 if (of_driver_match_device(dev, drv))
112 if (acpi_driver_match_device(dev, drv))
116 return !!spi_match_id(sdrv->id_table, spi);
118 return strcmp(spi->modalias, drv->name) == 0;
121 static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
123 const struct spi_device *spi = to_spi_device(dev);
126 rc = acpi_device_uevent_modalias(dev, env);
130 add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
134 #ifdef CONFIG_PM_SLEEP
135 static int spi_legacy_suspend(struct device *dev, pm_message_t message)
138 struct spi_driver *drv = to_spi_driver(dev->driver);
140 /* suspend will stop irqs and dma; no more i/o */
143 value = drv->suspend(to_spi_device(dev), message);
145 dev_dbg(dev, "... can't suspend\n");
150 static int spi_legacy_resume(struct device *dev)
153 struct spi_driver *drv = to_spi_driver(dev->driver);
155 /* resume may restart the i/o queue */
158 value = drv->resume(to_spi_device(dev));
160 dev_dbg(dev, "... can't resume\n");
165 static int spi_pm_suspend(struct device *dev)
167 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
170 return pm_generic_suspend(dev);
172 return spi_legacy_suspend(dev, PMSG_SUSPEND);
175 static int spi_pm_resume(struct device *dev)
177 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
180 return pm_generic_resume(dev);
182 return spi_legacy_resume(dev);
185 static int spi_pm_freeze(struct device *dev)
187 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
190 return pm_generic_freeze(dev);
192 return spi_legacy_suspend(dev, PMSG_FREEZE);
195 static int spi_pm_thaw(struct device *dev)
197 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
200 return pm_generic_thaw(dev);
202 return spi_legacy_resume(dev);
205 static int spi_pm_poweroff(struct device *dev)
207 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
210 return pm_generic_poweroff(dev);
212 return spi_legacy_suspend(dev, PMSG_HIBERNATE);
215 static int spi_pm_restore(struct device *dev)
217 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
220 return pm_generic_restore(dev);
222 return spi_legacy_resume(dev);
225 #define spi_pm_suspend NULL
226 #define spi_pm_resume NULL
227 #define spi_pm_freeze NULL
228 #define spi_pm_thaw NULL
229 #define spi_pm_poweroff NULL
230 #define spi_pm_restore NULL
233 static const struct dev_pm_ops spi_pm = {
234 .suspend = spi_pm_suspend,
235 .resume = spi_pm_resume,
236 .freeze = spi_pm_freeze,
238 .poweroff = spi_pm_poweroff,
239 .restore = spi_pm_restore,
241 pm_generic_runtime_suspend,
242 pm_generic_runtime_resume,
247 struct bus_type spi_bus_type = {
249 .dev_groups = spi_dev_groups,
250 .match = spi_match_device,
251 .uevent = spi_uevent,
254 EXPORT_SYMBOL_GPL(spi_bus_type);
257 static int spi_drv_probe(struct device *dev)
259 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
260 struct spi_device *spi = to_spi_device(dev);
263 acpi_dev_pm_attach(&spi->dev, true);
264 ret = sdrv->probe(spi);
266 acpi_dev_pm_detach(&spi->dev, true);
271 static int spi_drv_remove(struct device *dev)
273 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
274 struct spi_device *spi = to_spi_device(dev);
277 ret = sdrv->remove(spi);
278 acpi_dev_pm_detach(&spi->dev, true);
283 static void spi_drv_shutdown(struct device *dev)
285 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
287 sdrv->shutdown(to_spi_device(dev));
291 * spi_register_driver - register a SPI driver
292 * @sdrv: the driver to register
295 int spi_register_driver(struct spi_driver *sdrv)
297 sdrv->driver.bus = &spi_bus_type;
299 sdrv->driver.probe = spi_drv_probe;
301 sdrv->driver.remove = spi_drv_remove;
303 sdrv->driver.shutdown = spi_drv_shutdown;
304 return driver_register(&sdrv->driver);
306 EXPORT_SYMBOL_GPL(spi_register_driver);
308 /*-------------------------------------------------------------------------*/
310 /* SPI devices should normally not be created by SPI device drivers; that
311 * would make them board-specific. Similarly with SPI master drivers.
312 * Device registration normally goes into like arch/.../mach.../board-YYY.c
313 * with other readonly (flashable) information about mainboard devices.
317 struct list_head list;
318 struct spi_board_info board_info;
321 static LIST_HEAD(board_list);
322 static LIST_HEAD(spi_master_list);
325 * Used to protect add/del opertion for board_info list and
326 * spi_master list, and their matching process
328 static DEFINE_MUTEX(board_lock);
331 * spi_alloc_device - Allocate a new SPI device
332 * @master: Controller to which device is connected
335 * Allows a driver to allocate and initialize a spi_device without
336 * registering it immediately. This allows a driver to directly
337 * fill the spi_device with device parameters before calling
338 * spi_add_device() on it.
340 * Caller is responsible to call spi_add_device() on the returned
341 * spi_device structure to add it to the SPI master. If the caller
342 * needs to discard the spi_device without adding it, then it should
343 * call spi_dev_put() on it.
345 * Returns a pointer to the new device, or NULL.
347 struct spi_device *spi_alloc_device(struct spi_master *master)
349 struct spi_device *spi;
350 struct device *dev = master->dev.parent;
352 if (!spi_master_get(master))
355 spi = kzalloc(sizeof(*spi), GFP_KERNEL);
357 dev_err(dev, "cannot alloc spi_device\n");
358 spi_master_put(master);
362 spi->master = master;
363 spi->dev.parent = &master->dev;
364 spi->dev.bus = &spi_bus_type;
365 spi->dev.release = spidev_release;
366 spi->cs_gpio = -ENOENT;
367 device_initialize(&spi->dev);
370 EXPORT_SYMBOL_GPL(spi_alloc_device);
372 static void spi_dev_set_name(struct spi_device *spi)
374 struct acpi_device *adev = ACPI_COMPANION(&spi->dev);
377 dev_set_name(&spi->dev, "spi-%s", acpi_dev_name(adev));
381 dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
385 static int spi_dev_check(struct device *dev, void *data)
387 struct spi_device *spi = to_spi_device(dev);
388 struct spi_device *new_spi = data;
390 if (spi->master == new_spi->master &&
391 spi->chip_select == new_spi->chip_select)
397 * spi_add_device - Add spi_device allocated with spi_alloc_device
398 * @spi: spi_device to register
400 * Companion function to spi_alloc_device. Devices allocated with
401 * spi_alloc_device can be added onto the spi bus with this function.
403 * Returns 0 on success; negative errno on failure
405 int spi_add_device(struct spi_device *spi)
407 static DEFINE_MUTEX(spi_add_lock);
408 struct spi_master *master = spi->master;
409 struct device *dev = master->dev.parent;
412 /* Chipselects are numbered 0..max; validate. */
413 if (spi->chip_select >= master->num_chipselect) {
414 dev_err(dev, "cs%d >= max %d\n",
416 master->num_chipselect);
420 /* Set the bus ID string */
421 spi_dev_set_name(spi);
423 /* We need to make sure there's no other device with this
424 * chipselect **BEFORE** we call setup(), else we'll trash
425 * its configuration. Lock against concurrent add() calls.
427 mutex_lock(&spi_add_lock);
429 status = bus_for_each_dev(&spi_bus_type, NULL, spi, spi_dev_check);
431 dev_err(dev, "chipselect %d already in use\n",
436 if (master->cs_gpios)
437 spi->cs_gpio = master->cs_gpios[spi->chip_select];
439 /* Drivers may modify this initial i/o setup, but will
440 * normally rely on the device being setup. Devices
441 * using SPI_CS_HIGH can't coexist well otherwise...
443 status = spi_setup(spi);
445 dev_err(dev, "can't setup %s, status %d\n",
446 dev_name(&spi->dev), status);
450 /* Device may be bound to an active driver when this returns */
451 status = device_add(&spi->dev);
453 dev_err(dev, "can't add %s, status %d\n",
454 dev_name(&spi->dev), status);
456 dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
459 mutex_unlock(&spi_add_lock);
462 EXPORT_SYMBOL_GPL(spi_add_device);
465 * spi_new_device - instantiate one new SPI device
466 * @master: Controller to which device is connected
467 * @chip: Describes the SPI device
470 * On typical mainboards, this is purely internal; and it's not needed
471 * after board init creates the hard-wired devices. Some development
472 * platforms may not be able to use spi_register_board_info though, and
473 * this is exported so that for example a USB or parport based adapter
474 * driver could add devices (which it would learn about out-of-band).
476 * Returns the new device, or NULL.
478 struct spi_device *spi_new_device(struct spi_master *master,
479 struct spi_board_info *chip)
481 struct spi_device *proxy;
484 /* NOTE: caller did any chip->bus_num checks necessary.
486 * Also, unless we change the return value convention to use
487 * error-or-pointer (not NULL-or-pointer), troubleshootability
488 * suggests syslogged diagnostics are best here (ugh).
491 proxy = spi_alloc_device(master);
495 WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
497 proxy->chip_select = chip->chip_select;
498 proxy->max_speed_hz = chip->max_speed_hz;
499 proxy->mode = chip->mode;
500 proxy->irq = chip->irq;
501 strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
502 proxy->dev.platform_data = (void *) chip->platform_data;
503 proxy->controller_data = chip->controller_data;
504 proxy->controller_state = NULL;
506 status = spi_add_device(proxy);
514 EXPORT_SYMBOL_GPL(spi_new_device);
516 static void spi_match_master_to_boardinfo(struct spi_master *master,
517 struct spi_board_info *bi)
519 struct spi_device *dev;
521 if (master->bus_num != bi->bus_num)
524 dev = spi_new_device(master, bi);
526 dev_err(master->dev.parent, "can't create new device for %s\n",
531 * spi_register_board_info - register SPI devices for a given board
532 * @info: array of chip descriptors
533 * @n: how many descriptors are provided
536 * Board-specific early init code calls this (probably during arch_initcall)
537 * with segments of the SPI device table. Any device nodes are created later,
538 * after the relevant parent SPI controller (bus_num) is defined. We keep
539 * this table of devices forever, so that reloading a controller driver will
540 * not make Linux forget about these hard-wired devices.
542 * Other code can also call this, e.g. a particular add-on board might provide
543 * SPI devices through its expansion connector, so code initializing that board
544 * would naturally declare its SPI devices.
546 * The board info passed can safely be __initdata ... but be careful of
547 * any embedded pointers (platform_data, etc), they're copied as-is.
549 int spi_register_board_info(struct spi_board_info const *info, unsigned n)
551 struct boardinfo *bi;
554 bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
558 for (i = 0; i < n; i++, bi++, info++) {
559 struct spi_master *master;
561 memcpy(&bi->board_info, info, sizeof(*info));
562 mutex_lock(&board_lock);
563 list_add_tail(&bi->list, &board_list);
564 list_for_each_entry(master, &spi_master_list, list)
565 spi_match_master_to_boardinfo(master, &bi->board_info);
566 mutex_unlock(&board_lock);
572 /*-------------------------------------------------------------------------*/
574 static void spi_set_cs(struct spi_device *spi, bool enable)
576 if (spi->mode & SPI_CS_HIGH)
579 if (spi->cs_gpio >= 0)
580 gpio_set_value(spi->cs_gpio, !enable);
581 else if (spi->master->set_cs)
582 spi->master->set_cs(spi, !enable);
585 static int spi_map_msg(struct spi_master *master, struct spi_message *msg)
587 struct device *dev = master->dev.parent;
588 struct device *tx_dev, *rx_dev;
589 struct spi_transfer *xfer;
591 if (msg->is_dma_mapped || !master->can_dma)
594 tx_dev = &master->dma_tx->dev->device;
595 rx_dev = &master->dma_rx->dev->device;
597 list_for_each_entry(xfer, &msg->transfers, transfer_list) {
598 if (!master->can_dma(master, msg->spi, xfer))
601 if (xfer->tx_buf != NULL) {
602 xfer->tx_dma = dma_map_single(tx_dev,
603 (void *)xfer->tx_buf,
606 if (dma_mapping_error(dev, xfer->tx_dma)) {
607 dev_err(dev, "dma_map_single Tx failed\n");
612 if (xfer->rx_buf != NULL) {
613 xfer->rx_dma = dma_map_single(rx_dev,
614 xfer->rx_buf, xfer->len,
616 if (dma_mapping_error(dev, xfer->rx_dma)) {
617 dev_err(dev, "dma_map_single Rx failed\n");
618 dma_unmap_single(tx_dev, xfer->tx_dma,
619 xfer->len, DMA_TO_DEVICE);
625 master->cur_msg_mapped = true;
630 static int spi_unmap_msg(struct spi_master *master, struct spi_message *msg)
632 struct spi_transfer *xfer;
633 struct device *tx_dev, *rx_dev;
635 if (!master->cur_msg_mapped || msg->is_dma_mapped || !master->can_dma)
638 tx_dev = &master->dma_tx->dev->device;
639 rx_dev = &master->dma_rx->dev->device;
641 list_for_each_entry(xfer, &msg->transfers, transfer_list) {
642 if (!master->can_dma(master, msg->spi, xfer))
646 dma_unmap_single(rx_dev, xfer->rx_dma, xfer->len,
649 dma_unmap_single(tx_dev, xfer->tx_dma, xfer->len,
657 * spi_transfer_one_message - Default implementation of transfer_one_message()
659 * This is a standard implementation of transfer_one_message() for
660 * drivers which impelment a transfer_one() operation. It provides
661 * standard handling of delays and chip select management.
663 static int spi_transfer_one_message(struct spi_master *master,
664 struct spi_message *msg)
666 struct spi_transfer *xfer;
668 bool keep_cs = false;
671 spi_set_cs(msg->spi, true);
673 list_for_each_entry(xfer, &msg->transfers, transfer_list) {
674 trace_spi_transfer_start(msg, xfer);
676 reinit_completion(&master->xfer_completion);
678 ret = master->transfer_one(master, msg->spi, xfer);
680 dev_err(&msg->spi->dev,
681 "SPI transfer failed: %d\n", ret);
687 wait_for_completion(&master->xfer_completion);
690 trace_spi_transfer_stop(msg, xfer);
692 if (msg->status != -EINPROGRESS)
695 if (xfer->delay_usecs)
696 udelay(xfer->delay_usecs);
698 if (xfer->cs_change) {
699 if (list_is_last(&xfer->transfer_list,
704 spi_set_cs(msg->spi, cur_cs);
708 msg->actual_length += xfer->len;
712 if (ret != 0 || !keep_cs)
713 spi_set_cs(msg->spi, false);
715 if (msg->status == -EINPROGRESS)
718 spi_finalize_current_message(master);
724 * spi_finalize_current_transfer - report completion of a transfer
726 * Called by SPI drivers using the core transfer_one_message()
727 * implementation to notify it that the current interrupt driven
728 * transfer has finished and the next one may be scheduled.
730 void spi_finalize_current_transfer(struct spi_master *master)
732 complete(&master->xfer_completion);
734 EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);
737 * spi_pump_messages - kthread work function which processes spi message queue
738 * @work: pointer to kthread work struct contained in the master struct
740 * This function checks if there is any spi message in the queue that
741 * needs processing and if so call out to the driver to initialize hardware
742 * and transfer each message.
745 static void spi_pump_messages(struct kthread_work *work)
747 struct spi_master *master =
748 container_of(work, struct spi_master, pump_messages);
750 bool was_busy = false;
753 /* Lock queue and check for queue work */
754 spin_lock_irqsave(&master->queue_lock, flags);
755 if (list_empty(&master->queue) || !master->running) {
757 spin_unlock_irqrestore(&master->queue_lock, flags);
760 master->busy = false;
761 spin_unlock_irqrestore(&master->queue_lock, flags);
762 if (master->unprepare_transfer_hardware &&
763 master->unprepare_transfer_hardware(master))
764 dev_err(&master->dev,
765 "failed to unprepare transfer hardware\n");
766 if (master->auto_runtime_pm) {
767 pm_runtime_mark_last_busy(master->dev.parent);
768 pm_runtime_put_autosuspend(master->dev.parent);
770 trace_spi_master_idle(master);
774 /* Make sure we are not already running a message */
775 if (master->cur_msg) {
776 spin_unlock_irqrestore(&master->queue_lock, flags);
779 /* Extract head of queue */
781 list_first_entry(&master->queue, struct spi_message, queue);
783 list_del_init(&master->cur_msg->queue);
788 spin_unlock_irqrestore(&master->queue_lock, flags);
790 if (!was_busy && master->auto_runtime_pm) {
791 ret = pm_runtime_get_sync(master->dev.parent);
793 dev_err(&master->dev, "Failed to power device: %d\n",
800 trace_spi_master_busy(master);
802 if (!was_busy && master->prepare_transfer_hardware) {
803 ret = master->prepare_transfer_hardware(master);
805 dev_err(&master->dev,
806 "failed to prepare transfer hardware\n");
808 if (master->auto_runtime_pm)
809 pm_runtime_put(master->dev.parent);
814 trace_spi_message_start(master->cur_msg);
816 if (master->prepare_message) {
817 ret = master->prepare_message(master, master->cur_msg);
819 dev_err(&master->dev,
820 "failed to prepare message: %d\n", ret);
821 master->cur_msg->status = ret;
822 spi_finalize_current_message(master);
825 master->cur_msg_prepared = true;
828 ret = spi_map_msg(master, master->cur_msg);
830 master->cur_msg->status = ret;
831 spi_finalize_current_message(master);
835 ret = master->transfer_one_message(master, master->cur_msg);
837 dev_err(&master->dev,
838 "failed to transfer one message from queue: %d\n", ret);
839 master->cur_msg->status = ret;
840 spi_finalize_current_message(master);
845 static int spi_init_queue(struct spi_master *master)
847 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
849 INIT_LIST_HEAD(&master->queue);
850 spin_lock_init(&master->queue_lock);
852 master->running = false;
853 master->busy = false;
855 init_kthread_worker(&master->kworker);
856 master->kworker_task = kthread_run(kthread_worker_fn,
857 &master->kworker, "%s",
858 dev_name(&master->dev));
859 if (IS_ERR(master->kworker_task)) {
860 dev_err(&master->dev, "failed to create message pump task\n");
863 init_kthread_work(&master->pump_messages, spi_pump_messages);
866 * Master config will indicate if this controller should run the
867 * message pump with high (realtime) priority to reduce the transfer
868 * latency on the bus by minimising the delay between a transfer
869 * request and the scheduling of the message pump thread. Without this
870 * setting the message pump thread will remain at default priority.
873 dev_info(&master->dev,
874 "will run message pump with realtime priority\n");
875 sched_setscheduler(master->kworker_task, SCHED_FIFO, ¶m);
882 * spi_get_next_queued_message() - called by driver to check for queued
884 * @master: the master to check for queued messages
886 * If there are more messages in the queue, the next message is returned from
889 struct spi_message *spi_get_next_queued_message(struct spi_master *master)
891 struct spi_message *next;
894 /* get a pointer to the next message, if any */
895 spin_lock_irqsave(&master->queue_lock, flags);
896 next = list_first_entry_or_null(&master->queue, struct spi_message,
898 spin_unlock_irqrestore(&master->queue_lock, flags);
902 EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
905 * spi_finalize_current_message() - the current message is complete
906 * @master: the master to return the message to
908 * Called by the driver to notify the core that the message in the front of the
909 * queue is complete and can be removed from the queue.
911 void spi_finalize_current_message(struct spi_master *master)
913 struct spi_message *mesg;
917 spin_lock_irqsave(&master->queue_lock, flags);
918 mesg = master->cur_msg;
919 master->cur_msg = NULL;
921 queue_kthread_work(&master->kworker, &master->pump_messages);
922 spin_unlock_irqrestore(&master->queue_lock, flags);
924 spi_unmap_msg(master, mesg);
926 if (master->cur_msg_prepared && master->unprepare_message) {
927 ret = master->unprepare_message(master, mesg);
929 dev_err(&master->dev,
930 "failed to unprepare message: %d\n", ret);
933 master->cur_msg_prepared = false;
937 mesg->complete(mesg->context);
939 trace_spi_message_done(mesg);
941 EXPORT_SYMBOL_GPL(spi_finalize_current_message);
943 static int spi_start_queue(struct spi_master *master)
947 spin_lock_irqsave(&master->queue_lock, flags);
949 if (master->running || master->busy) {
950 spin_unlock_irqrestore(&master->queue_lock, flags);
954 master->running = true;
955 master->cur_msg = NULL;
956 spin_unlock_irqrestore(&master->queue_lock, flags);
958 queue_kthread_work(&master->kworker, &master->pump_messages);
963 static int spi_stop_queue(struct spi_master *master)
966 unsigned limit = 500;
969 spin_lock_irqsave(&master->queue_lock, flags);
972 * This is a bit lame, but is optimized for the common execution path.
973 * A wait_queue on the master->busy could be used, but then the common
974 * execution path (pump_messages) would be required to call wake_up or
975 * friends on every SPI message. Do this instead.
977 while ((!list_empty(&master->queue) || master->busy) && limit--) {
978 spin_unlock_irqrestore(&master->queue_lock, flags);
980 spin_lock_irqsave(&master->queue_lock, flags);
983 if (!list_empty(&master->queue) || master->busy)
986 master->running = false;
988 spin_unlock_irqrestore(&master->queue_lock, flags);
991 dev_warn(&master->dev,
992 "could not stop message queue\n");
998 static int spi_destroy_queue(struct spi_master *master)
1002 ret = spi_stop_queue(master);
1005 * flush_kthread_worker will block until all work is done.
1006 * If the reason that stop_queue timed out is that the work will never
1007 * finish, then it does no good to call flush/stop thread, so
1011 dev_err(&master->dev, "problem destroying queue\n");
1015 flush_kthread_worker(&master->kworker);
1016 kthread_stop(master->kworker_task);
1022 * spi_queued_transfer - transfer function for queued transfers
1023 * @spi: spi device which is requesting transfer
1024 * @msg: spi message which is to handled is queued to driver queue
1026 static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
1028 struct spi_master *master = spi->master;
1029 unsigned long flags;
1031 spin_lock_irqsave(&master->queue_lock, flags);
1033 if (!master->running) {
1034 spin_unlock_irqrestore(&master->queue_lock, flags);
1037 msg->actual_length = 0;
1038 msg->status = -EINPROGRESS;
1040 list_add_tail(&msg->queue, &master->queue);
1042 queue_kthread_work(&master->kworker, &master->pump_messages);
1044 spin_unlock_irqrestore(&master->queue_lock, flags);
1048 static int spi_master_initialize_queue(struct spi_master *master)
1052 master->queued = true;
1053 master->transfer = spi_queued_transfer;
1054 if (!master->transfer_one_message)
1055 master->transfer_one_message = spi_transfer_one_message;
1057 /* Initialize and start queue */
1058 ret = spi_init_queue(master);
1060 dev_err(&master->dev, "problem initializing queue\n");
1061 goto err_init_queue;
1063 ret = spi_start_queue(master);
1065 dev_err(&master->dev, "problem starting queue\n");
1066 goto err_start_queue;
1073 spi_destroy_queue(master);
1077 /*-------------------------------------------------------------------------*/
1079 #if defined(CONFIG_OF)
1081 * of_register_spi_devices() - Register child devices onto the SPI bus
1082 * @master: Pointer to spi_master device
1084 * Registers an spi_device for each child node of master node which has a 'reg'
1087 static void of_register_spi_devices(struct spi_master *master)
1089 struct spi_device *spi;
1090 struct device_node *nc;
1094 if (!master->dev.of_node)
1097 for_each_available_child_of_node(master->dev.of_node, nc) {
1098 /* Alloc an spi_device */
1099 spi = spi_alloc_device(master);
1101 dev_err(&master->dev, "spi_device alloc error for %s\n",
1107 /* Select device driver */
1108 if (of_modalias_node(nc, spi->modalias,
1109 sizeof(spi->modalias)) < 0) {
1110 dev_err(&master->dev, "cannot find modalias for %s\n",
1116 /* Device address */
1117 rc = of_property_read_u32(nc, "reg", &value);
1119 dev_err(&master->dev, "%s has no valid 'reg' property (%d)\n",
1124 spi->chip_select = value;
1126 /* Mode (clock phase/polarity/etc.) */
1127 if (of_find_property(nc, "spi-cpha", NULL))
1128 spi->mode |= SPI_CPHA;
1129 if (of_find_property(nc, "spi-cpol", NULL))
1130 spi->mode |= SPI_CPOL;
1131 if (of_find_property(nc, "spi-cs-high", NULL))
1132 spi->mode |= SPI_CS_HIGH;
1133 if (of_find_property(nc, "spi-3wire", NULL))
1134 spi->mode |= SPI_3WIRE;
1136 /* Device DUAL/QUAD mode */
1137 if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
1142 spi->mode |= SPI_TX_DUAL;
1145 spi->mode |= SPI_TX_QUAD;
1148 dev_err(&master->dev,
1149 "spi-tx-bus-width %d not supported\n",
1156 if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
1161 spi->mode |= SPI_RX_DUAL;
1164 spi->mode |= SPI_RX_QUAD;
1167 dev_err(&master->dev,
1168 "spi-rx-bus-width %d not supported\n",
1176 rc = of_property_read_u32(nc, "spi-max-frequency", &value);
1178 dev_err(&master->dev, "%s has no valid 'spi-max-frequency' property (%d)\n",
1183 spi->max_speed_hz = value;
1186 spi->irq = irq_of_parse_and_map(nc, 0);
1188 /* Store a pointer to the node in the device structure */
1190 spi->dev.of_node = nc;
1192 /* Register the new device */
1193 request_module("%s%s", SPI_MODULE_PREFIX, spi->modalias);
1194 rc = spi_add_device(spi);
1196 dev_err(&master->dev, "spi_device register error %s\n",
1204 static void of_register_spi_devices(struct spi_master *master) { }
1208 static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
1210 struct spi_device *spi = data;
1212 if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
1213 struct acpi_resource_spi_serialbus *sb;
1215 sb = &ares->data.spi_serial_bus;
1216 if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
1217 spi->chip_select = sb->device_selection;
1218 spi->max_speed_hz = sb->connection_speed;
1220 if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
1221 spi->mode |= SPI_CPHA;
1222 if (sb->clock_polarity == ACPI_SPI_START_HIGH)
1223 spi->mode |= SPI_CPOL;
1224 if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
1225 spi->mode |= SPI_CS_HIGH;
1227 } else if (spi->irq < 0) {
1230 if (acpi_dev_resource_interrupt(ares, 0, &r))
1234 /* Always tell the ACPI core to skip this resource */
1238 static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
1239 void *data, void **return_value)
1241 struct spi_master *master = data;
1242 struct list_head resource_list;
1243 struct acpi_device *adev;
1244 struct spi_device *spi;
1247 if (acpi_bus_get_device(handle, &adev))
1249 if (acpi_bus_get_status(adev) || !adev->status.present)
1252 spi = spi_alloc_device(master);
1254 dev_err(&master->dev, "failed to allocate SPI device for %s\n",
1255 dev_name(&adev->dev));
1256 return AE_NO_MEMORY;
1259 ACPI_COMPANION_SET(&spi->dev, adev);
1262 INIT_LIST_HEAD(&resource_list);
1263 ret = acpi_dev_get_resources(adev, &resource_list,
1264 acpi_spi_add_resource, spi);
1265 acpi_dev_free_resource_list(&resource_list);
1267 if (ret < 0 || !spi->max_speed_hz) {
1272 adev->power.flags.ignore_parent = true;
1273 strlcpy(spi->modalias, acpi_device_hid(adev), sizeof(spi->modalias));
1274 if (spi_add_device(spi)) {
1275 adev->power.flags.ignore_parent = false;
1276 dev_err(&master->dev, "failed to add SPI device %s from ACPI\n",
1277 dev_name(&adev->dev));
1284 static void acpi_register_spi_devices(struct spi_master *master)
1289 handle = ACPI_HANDLE(master->dev.parent);
1293 status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
1294 acpi_spi_add_device, NULL,
1296 if (ACPI_FAILURE(status))
1297 dev_warn(&master->dev, "failed to enumerate SPI slaves\n");
1300 static inline void acpi_register_spi_devices(struct spi_master *master) {}
1301 #endif /* CONFIG_ACPI */
1303 static void spi_master_release(struct device *dev)
1305 struct spi_master *master;
1307 master = container_of(dev, struct spi_master, dev);
1311 static struct class spi_master_class = {
1312 .name = "spi_master",
1313 .owner = THIS_MODULE,
1314 .dev_release = spi_master_release,
1320 * spi_alloc_master - allocate SPI master controller
1321 * @dev: the controller, possibly using the platform_bus
1322 * @size: how much zeroed driver-private data to allocate; the pointer to this
1323 * memory is in the driver_data field of the returned device,
1324 * accessible with spi_master_get_devdata().
1325 * Context: can sleep
1327 * This call is used only by SPI master controller drivers, which are the
1328 * only ones directly touching chip registers. It's how they allocate
1329 * an spi_master structure, prior to calling spi_register_master().
1331 * This must be called from context that can sleep. It returns the SPI
1332 * master structure on success, else NULL.
1334 * The caller is responsible for assigning the bus number and initializing
1335 * the master's methods before calling spi_register_master(); and (after errors
1336 * adding the device) calling spi_master_put() and kfree() to prevent a memory
1339 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
1341 struct spi_master *master;
1346 master = kzalloc(size + sizeof(*master), GFP_KERNEL);
1350 device_initialize(&master->dev);
1351 master->bus_num = -1;
1352 master->num_chipselect = 1;
1353 master->dev.class = &spi_master_class;
1354 master->dev.parent = get_device(dev);
1355 spi_master_set_devdata(master, &master[1]);
1359 EXPORT_SYMBOL_GPL(spi_alloc_master);
1362 static int of_spi_register_master(struct spi_master *master)
1365 struct device_node *np = master->dev.of_node;
1370 nb = of_gpio_named_count(np, "cs-gpios");
1371 master->num_chipselect = max_t(int, nb, master->num_chipselect);
1373 /* Return error only for an incorrectly formed cs-gpios property */
1374 if (nb == 0 || nb == -ENOENT)
1379 cs = devm_kzalloc(&master->dev,
1380 sizeof(int) * master->num_chipselect,
1382 master->cs_gpios = cs;
1384 if (!master->cs_gpios)
1387 for (i = 0; i < master->num_chipselect; i++)
1390 for (i = 0; i < nb; i++)
1391 cs[i] = of_get_named_gpio(np, "cs-gpios", i);
1396 static int of_spi_register_master(struct spi_master *master)
1403 * spi_register_master - register SPI master controller
1404 * @master: initialized master, originally from spi_alloc_master()
1405 * Context: can sleep
1407 * SPI master controllers connect to their drivers using some non-SPI bus,
1408 * such as the platform bus. The final stage of probe() in that code
1409 * includes calling spi_register_master() to hook up to this SPI bus glue.
1411 * SPI controllers use board specific (often SOC specific) bus numbers,
1412 * and board-specific addressing for SPI devices combines those numbers
1413 * with chip select numbers. Since SPI does not directly support dynamic
1414 * device identification, boards need configuration tables telling which
1415 * chip is at which address.
1417 * This must be called from context that can sleep. It returns zero on
1418 * success, else a negative error code (dropping the master's refcount).
1419 * After a successful return, the caller is responsible for calling
1420 * spi_unregister_master().
1422 int spi_register_master(struct spi_master *master)
1424 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
1425 struct device *dev = master->dev.parent;
1426 struct boardinfo *bi;
1427 int status = -ENODEV;
1433 status = of_spi_register_master(master);
1437 /* even if it's just one always-selected device, there must
1438 * be at least one chipselect
1440 if (master->num_chipselect == 0)
1443 if ((master->bus_num < 0) && master->dev.of_node)
1444 master->bus_num = of_alias_get_id(master->dev.of_node, "spi");
1446 /* convention: dynamically assigned bus IDs count down from the max */
1447 if (master->bus_num < 0) {
1448 /* FIXME switch to an IDR based scheme, something like
1449 * I2C now uses, so we can't run out of "dynamic" IDs
1451 master->bus_num = atomic_dec_return(&dyn_bus_id);
1455 spin_lock_init(&master->bus_lock_spinlock);
1456 mutex_init(&master->bus_lock_mutex);
1457 master->bus_lock_flag = 0;
1458 init_completion(&master->xfer_completion);
1460 /* register the device, then userspace will see it.
1461 * registration fails if the bus ID is in use.
1463 dev_set_name(&master->dev, "spi%u", master->bus_num);
1464 status = device_add(&master->dev);
1467 dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
1468 dynamic ? " (dynamic)" : "");
1470 /* If we're using a queued driver, start the queue */
1471 if (master->transfer)
1472 dev_info(dev, "master is unqueued, this is deprecated\n");
1474 status = spi_master_initialize_queue(master);
1476 device_del(&master->dev);
1481 mutex_lock(&board_lock);
1482 list_add_tail(&master->list, &spi_master_list);
1483 list_for_each_entry(bi, &board_list, list)
1484 spi_match_master_to_boardinfo(master, &bi->board_info);
1485 mutex_unlock(&board_lock);
1487 /* Register devices from the device tree and ACPI */
1488 of_register_spi_devices(master);
1489 acpi_register_spi_devices(master);
1493 EXPORT_SYMBOL_GPL(spi_register_master);
1495 static void devm_spi_unregister(struct device *dev, void *res)
1497 spi_unregister_master(*(struct spi_master **)res);
1501 * dev_spi_register_master - register managed SPI master controller
1502 * @dev: device managing SPI master
1503 * @master: initialized master, originally from spi_alloc_master()
1504 * Context: can sleep
1506 * Register a SPI device as with spi_register_master() which will
1507 * automatically be unregister
1509 int devm_spi_register_master(struct device *dev, struct spi_master *master)
1511 struct spi_master **ptr;
1514 ptr = devres_alloc(devm_spi_unregister, sizeof(*ptr), GFP_KERNEL);
1518 ret = spi_register_master(master);
1521 devres_add(dev, ptr);
1528 EXPORT_SYMBOL_GPL(devm_spi_register_master);
1530 static int __unregister(struct device *dev, void *null)
1532 spi_unregister_device(to_spi_device(dev));
1537 * spi_unregister_master - unregister SPI master controller
1538 * @master: the master being unregistered
1539 * Context: can sleep
1541 * This call is used only by SPI master controller drivers, which are the
1542 * only ones directly touching chip registers.
1544 * This must be called from context that can sleep.
1546 void spi_unregister_master(struct spi_master *master)
1550 if (master->queued) {
1551 if (spi_destroy_queue(master))
1552 dev_err(&master->dev, "queue remove failed\n");
1555 mutex_lock(&board_lock);
1556 list_del(&master->list);
1557 mutex_unlock(&board_lock);
1559 dummy = device_for_each_child(&master->dev, NULL, __unregister);
1560 device_unregister(&master->dev);
1562 EXPORT_SYMBOL_GPL(spi_unregister_master);
1564 int spi_master_suspend(struct spi_master *master)
1568 /* Basically no-ops for non-queued masters */
1569 if (!master->queued)
1572 ret = spi_stop_queue(master);
1574 dev_err(&master->dev, "queue stop failed\n");
1578 EXPORT_SYMBOL_GPL(spi_master_suspend);
1580 int spi_master_resume(struct spi_master *master)
1584 if (!master->queued)
1587 ret = spi_start_queue(master);
1589 dev_err(&master->dev, "queue restart failed\n");
1593 EXPORT_SYMBOL_GPL(spi_master_resume);
1595 static int __spi_master_match(struct device *dev, const void *data)
1597 struct spi_master *m;
1598 const u16 *bus_num = data;
1600 m = container_of(dev, struct spi_master, dev);
1601 return m->bus_num == *bus_num;
1605 * spi_busnum_to_master - look up master associated with bus_num
1606 * @bus_num: the master's bus number
1607 * Context: can sleep
1609 * This call may be used with devices that are registered after
1610 * arch init time. It returns a refcounted pointer to the relevant
1611 * spi_master (which the caller must release), or NULL if there is
1612 * no such master registered.
1614 struct spi_master *spi_busnum_to_master(u16 bus_num)
1617 struct spi_master *master = NULL;
1619 dev = class_find_device(&spi_master_class, NULL, &bus_num,
1620 __spi_master_match);
1622 master = container_of(dev, struct spi_master, dev);
1623 /* reference got in class_find_device */
1626 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
1629 /*-------------------------------------------------------------------------*/
1631 /* Core methods for SPI master protocol drivers. Some of the
1632 * other core methods are currently defined as inline functions.
1636 * spi_setup - setup SPI mode and clock rate
1637 * @spi: the device whose settings are being modified
1638 * Context: can sleep, and no requests are queued to the device
1640 * SPI protocol drivers may need to update the transfer mode if the
1641 * device doesn't work with its default. They may likewise need
1642 * to update clock rates or word sizes from initial values. This function
1643 * changes those settings, and must be called from a context that can sleep.
1644 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
1645 * effect the next time the device is selected and data is transferred to
1646 * or from it. When this function returns, the spi device is deselected.
1648 * Note that this call will fail if the protocol driver specifies an option
1649 * that the underlying controller or its driver does not support. For
1650 * example, not all hardware supports wire transfers using nine bit words,
1651 * LSB-first wire encoding, or active-high chipselects.
1653 int spi_setup(struct spi_device *spi)
1658 /* check mode to prevent that DUAL and QUAD set at the same time
1660 if (((spi->mode & SPI_TX_DUAL) && (spi->mode & SPI_TX_QUAD)) ||
1661 ((spi->mode & SPI_RX_DUAL) && (spi->mode & SPI_RX_QUAD))) {
1663 "setup: can not select dual and quad at the same time\n");
1666 /* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
1668 if ((spi->mode & SPI_3WIRE) && (spi->mode &
1669 (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)))
1671 /* help drivers fail *cleanly* when they need options
1672 * that aren't supported with their current master
1674 bad_bits = spi->mode & ~spi->master->mode_bits;
1676 dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
1681 if (!spi->bits_per_word)
1682 spi->bits_per_word = 8;
1684 if (spi->master->setup)
1685 status = spi->master->setup(spi);
1687 dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s%u bits/w, %u Hz max --> %d\n",
1688 (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
1689 (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
1690 (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
1691 (spi->mode & SPI_3WIRE) ? "3wire, " : "",
1692 (spi->mode & SPI_LOOP) ? "loopback, " : "",
1693 spi->bits_per_word, spi->max_speed_hz,
1698 EXPORT_SYMBOL_GPL(spi_setup);
1700 static int __spi_validate(struct spi_device *spi, struct spi_message *message)
1702 struct spi_master *master = spi->master;
1703 struct spi_transfer *xfer;
1705 if (list_empty(&message->transfers))
1707 if (!message->complete)
1710 /* Half-duplex links include original MicroWire, and ones with
1711 * only one data pin like SPI_3WIRE (switches direction) or where
1712 * either MOSI or MISO is missing. They can also be caused by
1713 * software limitations.
1715 if ((master->flags & SPI_MASTER_HALF_DUPLEX)
1716 || (spi->mode & SPI_3WIRE)) {
1717 unsigned flags = master->flags;
1719 list_for_each_entry(xfer, &message->transfers, transfer_list) {
1720 if (xfer->rx_buf && xfer->tx_buf)
1722 if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
1724 if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
1730 * Set transfer bits_per_word and max speed as spi device default if
1731 * it is not set for this transfer.
1732 * Set transfer tx_nbits and rx_nbits as single transfer default
1733 * (SPI_NBITS_SINGLE) if it is not set for this transfer.
1735 list_for_each_entry(xfer, &message->transfers, transfer_list) {
1736 message->frame_length += xfer->len;
1737 if (!xfer->bits_per_word)
1738 xfer->bits_per_word = spi->bits_per_word;
1739 if (!xfer->speed_hz) {
1740 xfer->speed_hz = spi->max_speed_hz;
1741 if (master->max_speed_hz &&
1742 xfer->speed_hz > master->max_speed_hz)
1743 xfer->speed_hz = master->max_speed_hz;
1746 if (master->bits_per_word_mask) {
1747 /* Only 32 bits fit in the mask */
1748 if (xfer->bits_per_word > 32)
1750 if (!(master->bits_per_word_mask &
1751 BIT(xfer->bits_per_word - 1)))
1755 if (xfer->speed_hz && master->min_speed_hz &&
1756 xfer->speed_hz < master->min_speed_hz)
1758 if (xfer->speed_hz && master->max_speed_hz &&
1759 xfer->speed_hz > master->max_speed_hz)
1762 if (xfer->tx_buf && !xfer->tx_nbits)
1763 xfer->tx_nbits = SPI_NBITS_SINGLE;
1764 if (xfer->rx_buf && !xfer->rx_nbits)
1765 xfer->rx_nbits = SPI_NBITS_SINGLE;
1766 /* check transfer tx/rx_nbits:
1767 * 1. check the value matches one of single, dual and quad
1768 * 2. check tx/rx_nbits match the mode in spi_device
1771 if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
1772 xfer->tx_nbits != SPI_NBITS_DUAL &&
1773 xfer->tx_nbits != SPI_NBITS_QUAD)
1775 if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
1776 !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
1778 if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
1779 !(spi->mode & SPI_TX_QUAD))
1782 /* check transfer rx_nbits */
1784 if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
1785 xfer->rx_nbits != SPI_NBITS_DUAL &&
1786 xfer->rx_nbits != SPI_NBITS_QUAD)
1788 if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
1789 !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
1791 if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
1792 !(spi->mode & SPI_RX_QUAD))
1797 message->status = -EINPROGRESS;
1802 static int __spi_async(struct spi_device *spi, struct spi_message *message)
1804 struct spi_master *master = spi->master;
1808 trace_spi_message_submit(message);
1810 return master->transfer(spi, message);
1814 * spi_async - asynchronous SPI transfer
1815 * @spi: device with which data will be exchanged
1816 * @message: describes the data transfers, including completion callback
1817 * Context: any (irqs may be blocked, etc)
1819 * This call may be used in_irq and other contexts which can't sleep,
1820 * as well as from task contexts which can sleep.
1822 * The completion callback is invoked in a context which can't sleep.
1823 * Before that invocation, the value of message->status is undefined.
1824 * When the callback is issued, message->status holds either zero (to
1825 * indicate complete success) or a negative error code. After that
1826 * callback returns, the driver which issued the transfer request may
1827 * deallocate the associated memory; it's no longer in use by any SPI
1828 * core or controller driver code.
1830 * Note that although all messages to a spi_device are handled in
1831 * FIFO order, messages may go to different devices in other orders.
1832 * Some device might be higher priority, or have various "hard" access
1833 * time requirements, for example.
1835 * On detection of any fault during the transfer, processing of
1836 * the entire message is aborted, and the device is deselected.
1837 * Until returning from the associated message completion callback,
1838 * no other spi_message queued to that device will be processed.
1839 * (This rule applies equally to all the synchronous transfer calls,
1840 * which are wrappers around this core asynchronous primitive.)
1842 int spi_async(struct spi_device *spi, struct spi_message *message)
1844 struct spi_master *master = spi->master;
1846 unsigned long flags;
1848 ret = __spi_validate(spi, message);
1852 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1854 if (master->bus_lock_flag)
1857 ret = __spi_async(spi, message);
1859 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1863 EXPORT_SYMBOL_GPL(spi_async);
1866 * spi_async_locked - version of spi_async with exclusive bus usage
1867 * @spi: device with which data will be exchanged
1868 * @message: describes the data transfers, including completion callback
1869 * Context: any (irqs may be blocked, etc)
1871 * This call may be used in_irq and other contexts which can't sleep,
1872 * as well as from task contexts which can sleep.
1874 * The completion callback is invoked in a context which can't sleep.
1875 * Before that invocation, the value of message->status is undefined.
1876 * When the callback is issued, message->status holds either zero (to
1877 * indicate complete success) or a negative error code. After that
1878 * callback returns, the driver which issued the transfer request may
1879 * deallocate the associated memory; it's no longer in use by any SPI
1880 * core or controller driver code.
1882 * Note that although all messages to a spi_device are handled in
1883 * FIFO order, messages may go to different devices in other orders.
1884 * Some device might be higher priority, or have various "hard" access
1885 * time requirements, for example.
1887 * On detection of any fault during the transfer, processing of
1888 * the entire message is aborted, and the device is deselected.
1889 * Until returning from the associated message completion callback,
1890 * no other spi_message queued to that device will be processed.
1891 * (This rule applies equally to all the synchronous transfer calls,
1892 * which are wrappers around this core asynchronous primitive.)
1894 int spi_async_locked(struct spi_device *spi, struct spi_message *message)
1896 struct spi_master *master = spi->master;
1898 unsigned long flags;
1900 ret = __spi_validate(spi, message);
1904 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1906 ret = __spi_async(spi, message);
1908 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1913 EXPORT_SYMBOL_GPL(spi_async_locked);
1916 /*-------------------------------------------------------------------------*/
1918 /* Utility methods for SPI master protocol drivers, layered on
1919 * top of the core. Some other utility methods are defined as
1923 static void spi_complete(void *arg)
1928 static int __spi_sync(struct spi_device *spi, struct spi_message *message,
1931 DECLARE_COMPLETION_ONSTACK(done);
1933 struct spi_master *master = spi->master;
1935 message->complete = spi_complete;
1936 message->context = &done;
1939 mutex_lock(&master->bus_lock_mutex);
1941 status = spi_async_locked(spi, message);
1944 mutex_unlock(&master->bus_lock_mutex);
1947 wait_for_completion(&done);
1948 status = message->status;
1950 message->context = NULL;
1955 * spi_sync - blocking/synchronous SPI data transfers
1956 * @spi: device with which data will be exchanged
1957 * @message: describes the data transfers
1958 * Context: can sleep
1960 * This call may only be used from a context that may sleep. The sleep
1961 * is non-interruptible, and has no timeout. Low-overhead controller
1962 * drivers may DMA directly into and out of the message buffers.
1964 * Note that the SPI device's chip select is active during the message,
1965 * and then is normally disabled between messages. Drivers for some
1966 * frequently-used devices may want to minimize costs of selecting a chip,
1967 * by leaving it selected in anticipation that the next message will go
1968 * to the same chip. (That may increase power usage.)
1970 * Also, the caller is guaranteeing that the memory associated with the
1971 * message will not be freed before this call returns.
1973 * It returns zero on success, else a negative error code.
1975 int spi_sync(struct spi_device *spi, struct spi_message *message)
1977 return __spi_sync(spi, message, 0);
1979 EXPORT_SYMBOL_GPL(spi_sync);
1982 * spi_sync_locked - version of spi_sync with exclusive bus usage
1983 * @spi: device with which data will be exchanged
1984 * @message: describes the data transfers
1985 * Context: can sleep
1987 * This call may only be used from a context that may sleep. The sleep
1988 * is non-interruptible, and has no timeout. Low-overhead controller
1989 * drivers may DMA directly into and out of the message buffers.
1991 * This call should be used by drivers that require exclusive access to the
1992 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
1993 * be released by a spi_bus_unlock call when the exclusive access is over.
1995 * It returns zero on success, else a negative error code.
1997 int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
1999 return __spi_sync(spi, message, 1);
2001 EXPORT_SYMBOL_GPL(spi_sync_locked);
2004 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
2005 * @master: SPI bus master that should be locked for exclusive bus access
2006 * Context: can sleep
2008 * This call may only be used from a context that may sleep. The sleep
2009 * is non-interruptible, and has no timeout.
2011 * This call should be used by drivers that require exclusive access to the
2012 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
2013 * exclusive access is over. Data transfer must be done by spi_sync_locked
2014 * and spi_async_locked calls when the SPI bus lock is held.
2016 * It returns zero on success, else a negative error code.
2018 int spi_bus_lock(struct spi_master *master)
2020 unsigned long flags;
2022 mutex_lock(&master->bus_lock_mutex);
2024 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
2025 master->bus_lock_flag = 1;
2026 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
2028 /* mutex remains locked until spi_bus_unlock is called */
2032 EXPORT_SYMBOL_GPL(spi_bus_lock);
2035 * spi_bus_unlock - release the lock for exclusive SPI bus usage
2036 * @master: SPI bus master that was locked for exclusive bus access
2037 * Context: can sleep
2039 * This call may only be used from a context that may sleep. The sleep
2040 * is non-interruptible, and has no timeout.
2042 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
2045 * It returns zero on success, else a negative error code.
2047 int spi_bus_unlock(struct spi_master *master)
2049 master->bus_lock_flag = 0;
2051 mutex_unlock(&master->bus_lock_mutex);
2055 EXPORT_SYMBOL_GPL(spi_bus_unlock);
2057 /* portable code must never pass more than 32 bytes */
2058 #define SPI_BUFSIZ max(32, SMP_CACHE_BYTES)
2063 * spi_write_then_read - SPI synchronous write followed by read
2064 * @spi: device with which data will be exchanged
2065 * @txbuf: data to be written (need not be dma-safe)
2066 * @n_tx: size of txbuf, in bytes
2067 * @rxbuf: buffer into which data will be read (need not be dma-safe)
2068 * @n_rx: size of rxbuf, in bytes
2069 * Context: can sleep
2071 * This performs a half duplex MicroWire style transaction with the
2072 * device, sending txbuf and then reading rxbuf. The return value
2073 * is zero for success, else a negative errno status code.
2074 * This call may only be used from a context that may sleep.
2076 * Parameters to this routine are always copied using a small buffer;
2077 * portable code should never use this for more than 32 bytes.
2078 * Performance-sensitive or bulk transfer code should instead use
2079 * spi_{async,sync}() calls with dma-safe buffers.
2081 int spi_write_then_read(struct spi_device *spi,
2082 const void *txbuf, unsigned n_tx,
2083 void *rxbuf, unsigned n_rx)
2085 static DEFINE_MUTEX(lock);
2088 struct spi_message message;
2089 struct spi_transfer x[2];
2092 /* Use preallocated DMA-safe buffer if we can. We can't avoid
2093 * copying here, (as a pure convenience thing), but we can
2094 * keep heap costs out of the hot path unless someone else is
2095 * using the pre-allocated buffer or the transfer is too large.
2097 if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
2098 local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx),
2099 GFP_KERNEL | GFP_DMA);
2106 spi_message_init(&message);
2107 memset(x, 0, sizeof(x));
2110 spi_message_add_tail(&x[0], &message);
2114 spi_message_add_tail(&x[1], &message);
2117 memcpy(local_buf, txbuf, n_tx);
2118 x[0].tx_buf = local_buf;
2119 x[1].rx_buf = local_buf + n_tx;
2122 status = spi_sync(spi, &message);
2124 memcpy(rxbuf, x[1].rx_buf, n_rx);
2126 if (x[0].tx_buf == buf)
2127 mutex_unlock(&lock);
2133 EXPORT_SYMBOL_GPL(spi_write_then_read);
2135 /*-------------------------------------------------------------------------*/
2137 static int __init spi_init(void)
2141 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
2147 status = bus_register(&spi_bus_type);
2151 status = class_register(&spi_master_class);
2157 bus_unregister(&spi_bus_type);
2165 /* board_info is normally registered in arch_initcall(),
2166 * but even essential drivers wait till later
2168 * REVISIT only boardinfo really needs static linking. the rest (device and
2169 * driver registration) _could_ be dynamically linked (modular) ... costs
2170 * include needing to have boardinfo data structures be much more public.
2172 postcore_initcall(spi_init);