2 * spi.c - SPI init/core code
4 * Copyright (C) 2005 David Brownell
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 #include <linux/kernel.h>
22 #include <linux/device.h>
23 #include <linux/init.h>
24 #include <linux/cache.h>
25 #include <linux/mutex.h>
26 #include <linux/of_device.h>
27 #include <linux/slab.h>
28 #include <linux/mod_devicetable.h>
29 #include <linux/spi/spi.h>
30 #include <linux/of_spi.h>
31 #include <linux/pm_runtime.h>
33 static void spidev_release(struct device *dev)
35 struct spi_device *spi = to_spi_device(dev);
37 /* spi masters may cleanup for released devices */
38 if (spi->master->cleanup)
39 spi->master->cleanup(spi);
41 spi_master_put(spi->master);
46 modalias_show(struct device *dev, struct device_attribute *a, char *buf)
48 const struct spi_device *spi = to_spi_device(dev);
50 return sprintf(buf, "%s\n", spi->modalias);
53 static struct device_attribute spi_dev_attrs[] = {
58 /* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
59 * and the sysfs version makes coldplug work too.
62 static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
63 const struct spi_device *sdev)
66 if (!strcmp(sdev->modalias, id->name))
73 const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
75 const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
77 return spi_match_id(sdrv->id_table, sdev);
79 EXPORT_SYMBOL_GPL(spi_get_device_id);
81 static int spi_match_device(struct device *dev, struct device_driver *drv)
83 const struct spi_device *spi = to_spi_device(dev);
84 const struct spi_driver *sdrv = to_spi_driver(drv);
86 /* Attempt an OF style match */
87 if (of_driver_match_device(dev, drv))
91 return !!spi_match_id(sdrv->id_table, spi);
93 return strcmp(spi->modalias, drv->name) == 0;
96 static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
98 const struct spi_device *spi = to_spi_device(dev);
100 add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
104 #ifdef CONFIG_PM_SLEEP
105 static int spi_legacy_suspend(struct device *dev, pm_message_t message)
108 struct spi_driver *drv = to_spi_driver(dev->driver);
110 /* suspend will stop irqs and dma; no more i/o */
113 value = drv->suspend(to_spi_device(dev), message);
115 dev_dbg(dev, "... can't suspend\n");
120 static int spi_legacy_resume(struct device *dev)
123 struct spi_driver *drv = to_spi_driver(dev->driver);
125 /* resume may restart the i/o queue */
128 value = drv->resume(to_spi_device(dev));
130 dev_dbg(dev, "... can't resume\n");
135 static int spi_pm_suspend(struct device *dev)
137 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
140 return pm_generic_suspend(dev);
142 return spi_legacy_suspend(dev, PMSG_SUSPEND);
145 static int spi_pm_resume(struct device *dev)
147 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
150 return pm_generic_resume(dev);
152 return spi_legacy_resume(dev);
155 static int spi_pm_freeze(struct device *dev)
157 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
160 return pm_generic_freeze(dev);
162 return spi_legacy_suspend(dev, PMSG_FREEZE);
165 static int spi_pm_thaw(struct device *dev)
167 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
170 return pm_generic_thaw(dev);
172 return spi_legacy_resume(dev);
175 static int spi_pm_poweroff(struct device *dev)
177 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
180 return pm_generic_poweroff(dev);
182 return spi_legacy_suspend(dev, PMSG_HIBERNATE);
185 static int spi_pm_restore(struct device *dev)
187 const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
190 return pm_generic_restore(dev);
192 return spi_legacy_resume(dev);
195 #define spi_pm_suspend NULL
196 #define spi_pm_resume NULL
197 #define spi_pm_freeze NULL
198 #define spi_pm_thaw NULL
199 #define spi_pm_poweroff NULL
200 #define spi_pm_restore NULL
203 static const struct dev_pm_ops spi_pm = {
204 .suspend = spi_pm_suspend,
205 .resume = spi_pm_resume,
206 .freeze = spi_pm_freeze,
208 .poweroff = spi_pm_poweroff,
209 .restore = spi_pm_restore,
211 pm_generic_runtime_suspend,
212 pm_generic_runtime_resume,
213 pm_generic_runtime_idle
217 struct bus_type spi_bus_type = {
219 .dev_attrs = spi_dev_attrs,
220 .match = spi_match_device,
221 .uevent = spi_uevent,
224 EXPORT_SYMBOL_GPL(spi_bus_type);
227 static int spi_drv_probe(struct device *dev)
229 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
231 return sdrv->probe(to_spi_device(dev));
234 static int spi_drv_remove(struct device *dev)
236 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
238 return sdrv->remove(to_spi_device(dev));
241 static void spi_drv_shutdown(struct device *dev)
243 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
245 sdrv->shutdown(to_spi_device(dev));
249 * spi_register_driver - register a SPI driver
250 * @sdrv: the driver to register
253 int spi_register_driver(struct spi_driver *sdrv)
255 sdrv->driver.bus = &spi_bus_type;
257 sdrv->driver.probe = spi_drv_probe;
259 sdrv->driver.remove = spi_drv_remove;
261 sdrv->driver.shutdown = spi_drv_shutdown;
262 return driver_register(&sdrv->driver);
264 EXPORT_SYMBOL_GPL(spi_register_driver);
266 /*-------------------------------------------------------------------------*/
268 /* SPI devices should normally not be created by SPI device drivers; that
269 * would make them board-specific. Similarly with SPI master drivers.
270 * Device registration normally goes into like arch/.../mach.../board-YYY.c
271 * with other readonly (flashable) information about mainboard devices.
275 struct list_head list;
276 struct spi_board_info board_info;
279 static LIST_HEAD(board_list);
280 static LIST_HEAD(spi_master_list);
283 * Used to protect add/del opertion for board_info list and
284 * spi_master list, and their matching process
286 static DEFINE_MUTEX(board_lock);
289 * spi_alloc_device - Allocate a new SPI device
290 * @master: Controller to which device is connected
293 * Allows a driver to allocate and initialize a spi_device without
294 * registering it immediately. This allows a driver to directly
295 * fill the spi_device with device parameters before calling
296 * spi_add_device() on it.
298 * Caller is responsible to call spi_add_device() on the returned
299 * spi_device structure to add it to the SPI master. If the caller
300 * needs to discard the spi_device without adding it, then it should
301 * call spi_dev_put() on it.
303 * Returns a pointer to the new device, or NULL.
305 struct spi_device *spi_alloc_device(struct spi_master *master)
307 struct spi_device *spi;
308 struct device *dev = master->dev.parent;
310 if (!spi_master_get(master))
313 spi = kzalloc(sizeof *spi, GFP_KERNEL);
315 dev_err(dev, "cannot alloc spi_device\n");
316 spi_master_put(master);
320 spi->master = master;
321 spi->dev.parent = dev;
322 spi->dev.bus = &spi_bus_type;
323 spi->dev.release = spidev_release;
324 device_initialize(&spi->dev);
327 EXPORT_SYMBOL_GPL(spi_alloc_device);
330 * spi_add_device - Add spi_device allocated with spi_alloc_device
331 * @spi: spi_device to register
333 * Companion function to spi_alloc_device. Devices allocated with
334 * spi_alloc_device can be added onto the spi bus with this function.
336 * Returns 0 on success; negative errno on failure
338 int spi_add_device(struct spi_device *spi)
340 static DEFINE_MUTEX(spi_add_lock);
341 struct device *dev = spi->master->dev.parent;
345 /* Chipselects are numbered 0..max; validate. */
346 if (spi->chip_select >= spi->master->num_chipselect) {
347 dev_err(dev, "cs%d >= max %d\n",
349 spi->master->num_chipselect);
353 /* Set the bus ID string */
354 dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
358 /* We need to make sure there's no other device with this
359 * chipselect **BEFORE** we call setup(), else we'll trash
360 * its configuration. Lock against concurrent add() calls.
362 mutex_lock(&spi_add_lock);
364 d = bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));
366 dev_err(dev, "chipselect %d already in use\n",
373 /* Drivers may modify this initial i/o setup, but will
374 * normally rely on the device being setup. Devices
375 * using SPI_CS_HIGH can't coexist well otherwise...
377 status = spi_setup(spi);
379 dev_err(dev, "can't setup %s, status %d\n",
380 dev_name(&spi->dev), status);
384 /* Device may be bound to an active driver when this returns */
385 status = device_add(&spi->dev);
387 dev_err(dev, "can't add %s, status %d\n",
388 dev_name(&spi->dev), status);
390 dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
393 mutex_unlock(&spi_add_lock);
396 EXPORT_SYMBOL_GPL(spi_add_device);
399 * spi_new_device - instantiate one new SPI device
400 * @master: Controller to which device is connected
401 * @chip: Describes the SPI device
404 * On typical mainboards, this is purely internal; and it's not needed
405 * after board init creates the hard-wired devices. Some development
406 * platforms may not be able to use spi_register_board_info though, and
407 * this is exported so that for example a USB or parport based adapter
408 * driver could add devices (which it would learn about out-of-band).
410 * Returns the new device, or NULL.
412 struct spi_device *spi_new_device(struct spi_master *master,
413 struct spi_board_info *chip)
415 struct spi_device *proxy;
418 /* NOTE: caller did any chip->bus_num checks necessary.
420 * Also, unless we change the return value convention to use
421 * error-or-pointer (not NULL-or-pointer), troubleshootability
422 * suggests syslogged diagnostics are best here (ugh).
425 proxy = spi_alloc_device(master);
429 WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
431 proxy->chip_select = chip->chip_select;
432 proxy->max_speed_hz = chip->max_speed_hz;
433 proxy->mode = chip->mode;
434 proxy->irq = chip->irq;
435 strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
436 proxy->dev.platform_data = (void *) chip->platform_data;
437 proxy->controller_data = chip->controller_data;
438 proxy->controller_state = NULL;
440 status = spi_add_device(proxy);
448 EXPORT_SYMBOL_GPL(spi_new_device);
450 static void spi_match_master_to_boardinfo(struct spi_master *master,
451 struct spi_board_info *bi)
453 struct spi_device *dev;
455 if (master->bus_num != bi->bus_num)
458 dev = spi_new_device(master, bi);
460 dev_err(master->dev.parent, "can't create new device for %s\n",
465 * spi_register_board_info - register SPI devices for a given board
466 * @info: array of chip descriptors
467 * @n: how many descriptors are provided
470 * Board-specific early init code calls this (probably during arch_initcall)
471 * with segments of the SPI device table. Any device nodes are created later,
472 * after the relevant parent SPI controller (bus_num) is defined. We keep
473 * this table of devices forever, so that reloading a controller driver will
474 * not make Linux forget about these hard-wired devices.
476 * Other code can also call this, e.g. a particular add-on board might provide
477 * SPI devices through its expansion connector, so code initializing that board
478 * would naturally declare its SPI devices.
480 * The board info passed can safely be __initdata ... but be careful of
481 * any embedded pointers (platform_data, etc), they're copied as-is.
484 spi_register_board_info(struct spi_board_info const *info, unsigned n)
486 struct boardinfo *bi;
489 bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
493 for (i = 0; i < n; i++, bi++, info++) {
494 struct spi_master *master;
496 memcpy(&bi->board_info, info, sizeof(*info));
497 mutex_lock(&board_lock);
498 list_add_tail(&bi->list, &board_list);
499 list_for_each_entry(master, &spi_master_list, list)
500 spi_match_master_to_boardinfo(master, &bi->board_info);
501 mutex_unlock(&board_lock);
507 /*-------------------------------------------------------------------------*/
509 static void spi_master_release(struct device *dev)
511 struct spi_master *master;
513 master = container_of(dev, struct spi_master, dev);
517 static struct class spi_master_class = {
518 .name = "spi_master",
519 .owner = THIS_MODULE,
520 .dev_release = spi_master_release,
525 * spi_alloc_master - allocate SPI master controller
526 * @dev: the controller, possibly using the platform_bus
527 * @size: how much zeroed driver-private data to allocate; the pointer to this
528 * memory is in the driver_data field of the returned device,
529 * accessible with spi_master_get_devdata().
532 * This call is used only by SPI master controller drivers, which are the
533 * only ones directly touching chip registers. It's how they allocate
534 * an spi_master structure, prior to calling spi_register_master().
536 * This must be called from context that can sleep. It returns the SPI
537 * master structure on success, else NULL.
539 * The caller is responsible for assigning the bus number and initializing
540 * the master's methods before calling spi_register_master(); and (after errors
541 * adding the device) calling spi_master_put() to prevent a memory leak.
543 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
545 struct spi_master *master;
550 master = kzalloc(size + sizeof *master, GFP_KERNEL);
554 device_initialize(&master->dev);
555 master->dev.class = &spi_master_class;
556 master->dev.parent = get_device(dev);
557 spi_master_set_devdata(master, &master[1]);
561 EXPORT_SYMBOL_GPL(spi_alloc_master);
564 * spi_register_master - register SPI master controller
565 * @master: initialized master, originally from spi_alloc_master()
568 * SPI master controllers connect to their drivers using some non-SPI bus,
569 * such as the platform bus. The final stage of probe() in that code
570 * includes calling spi_register_master() to hook up to this SPI bus glue.
572 * SPI controllers use board specific (often SOC specific) bus numbers,
573 * and board-specific addressing for SPI devices combines those numbers
574 * with chip select numbers. Since SPI does not directly support dynamic
575 * device identification, boards need configuration tables telling which
576 * chip is at which address.
578 * This must be called from context that can sleep. It returns zero on
579 * success, else a negative error code (dropping the master's refcount).
580 * After a successful return, the caller is responsible for calling
581 * spi_unregister_master().
583 int spi_register_master(struct spi_master *master)
585 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
586 struct device *dev = master->dev.parent;
587 struct boardinfo *bi;
588 int status = -ENODEV;
594 /* even if it's just one always-selected device, there must
595 * be at least one chipselect
597 if (master->num_chipselect == 0)
600 /* convention: dynamically assigned bus IDs count down from the max */
601 if (master->bus_num < 0) {
602 /* FIXME switch to an IDR based scheme, something like
603 * I2C now uses, so we can't run out of "dynamic" IDs
605 master->bus_num = atomic_dec_return(&dyn_bus_id);
609 spin_lock_init(&master->bus_lock_spinlock);
610 mutex_init(&master->bus_lock_mutex);
611 master->bus_lock_flag = 0;
613 /* register the device, then userspace will see it.
614 * registration fails if the bus ID is in use.
616 dev_set_name(&master->dev, "spi%u", master->bus_num);
617 status = device_add(&master->dev);
620 dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
621 dynamic ? " (dynamic)" : "");
623 mutex_lock(&board_lock);
624 list_add_tail(&master->list, &spi_master_list);
625 list_for_each_entry(bi, &board_list, list)
626 spi_match_master_to_boardinfo(master, &bi->board_info);
627 mutex_unlock(&board_lock);
631 /* Register devices from the device tree */
632 of_register_spi_devices(master);
636 EXPORT_SYMBOL_GPL(spi_register_master);
639 static int __unregister(struct device *dev, void *null)
641 spi_unregister_device(to_spi_device(dev));
646 * spi_unregister_master - unregister SPI master controller
647 * @master: the master being unregistered
650 * This call is used only by SPI master controller drivers, which are the
651 * only ones directly touching chip registers.
653 * This must be called from context that can sleep.
655 void spi_unregister_master(struct spi_master *master)
659 mutex_lock(&board_lock);
660 list_del(&master->list);
661 mutex_unlock(&board_lock);
663 dummy = device_for_each_child(&master->dev, NULL, __unregister);
664 device_unregister(&master->dev);
666 EXPORT_SYMBOL_GPL(spi_unregister_master);
668 static int __spi_master_match(struct device *dev, void *data)
670 struct spi_master *m;
673 m = container_of(dev, struct spi_master, dev);
674 return m->bus_num == *bus_num;
678 * spi_busnum_to_master - look up master associated with bus_num
679 * @bus_num: the master's bus number
682 * This call may be used with devices that are registered after
683 * arch init time. It returns a refcounted pointer to the relevant
684 * spi_master (which the caller must release), or NULL if there is
685 * no such master registered.
687 struct spi_master *spi_busnum_to_master(u16 bus_num)
690 struct spi_master *master = NULL;
692 dev = class_find_device(&spi_master_class, NULL, &bus_num,
695 master = container_of(dev, struct spi_master, dev);
696 /* reference got in class_find_device */
699 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
702 /*-------------------------------------------------------------------------*/
704 /* Core methods for SPI master protocol drivers. Some of the
705 * other core methods are currently defined as inline functions.
709 * spi_setup - setup SPI mode and clock rate
710 * @spi: the device whose settings are being modified
711 * Context: can sleep, and no requests are queued to the device
713 * SPI protocol drivers may need to update the transfer mode if the
714 * device doesn't work with its default. They may likewise need
715 * to update clock rates or word sizes from initial values. This function
716 * changes those settings, and must be called from a context that can sleep.
717 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
718 * effect the next time the device is selected and data is transferred to
719 * or from it. When this function returns, the spi device is deselected.
721 * Note that this call will fail if the protocol driver specifies an option
722 * that the underlying controller or its driver does not support. For
723 * example, not all hardware supports wire transfers using nine bit words,
724 * LSB-first wire encoding, or active-high chipselects.
726 int spi_setup(struct spi_device *spi)
731 /* help drivers fail *cleanly* when they need options
732 * that aren't supported with their current master
734 bad_bits = spi->mode & ~spi->master->mode_bits;
736 dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
741 if (!spi->bits_per_word)
742 spi->bits_per_word = 8;
744 status = spi->master->setup(spi);
746 dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
747 "%u bits/w, %u Hz max --> %d\n",
748 (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
749 (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
750 (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
751 (spi->mode & SPI_3WIRE) ? "3wire, " : "",
752 (spi->mode & SPI_LOOP) ? "loopback, " : "",
753 spi->bits_per_word, spi->max_speed_hz,
758 EXPORT_SYMBOL_GPL(spi_setup);
760 static int __spi_async(struct spi_device *spi, struct spi_message *message)
762 struct spi_master *master = spi->master;
764 /* Half-duplex links include original MicroWire, and ones with
765 * only one data pin like SPI_3WIRE (switches direction) or where
766 * either MOSI or MISO is missing. They can also be caused by
767 * software limitations.
769 if ((master->flags & SPI_MASTER_HALF_DUPLEX)
770 || (spi->mode & SPI_3WIRE)) {
771 struct spi_transfer *xfer;
772 unsigned flags = master->flags;
774 list_for_each_entry(xfer, &message->transfers, transfer_list) {
775 if (xfer->rx_buf && xfer->tx_buf)
777 if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
779 if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
785 message->status = -EINPROGRESS;
786 return master->transfer(spi, message);
790 * spi_async - asynchronous SPI transfer
791 * @spi: device with which data will be exchanged
792 * @message: describes the data transfers, including completion callback
793 * Context: any (irqs may be blocked, etc)
795 * This call may be used in_irq and other contexts which can't sleep,
796 * as well as from task contexts which can sleep.
798 * The completion callback is invoked in a context which can't sleep.
799 * Before that invocation, the value of message->status is undefined.
800 * When the callback is issued, message->status holds either zero (to
801 * indicate complete success) or a negative error code. After that
802 * callback returns, the driver which issued the transfer request may
803 * deallocate the associated memory; it's no longer in use by any SPI
804 * core or controller driver code.
806 * Note that although all messages to a spi_device are handled in
807 * FIFO order, messages may go to different devices in other orders.
808 * Some device might be higher priority, or have various "hard" access
809 * time requirements, for example.
811 * On detection of any fault during the transfer, processing of
812 * the entire message is aborted, and the device is deselected.
813 * Until returning from the associated message completion callback,
814 * no other spi_message queued to that device will be processed.
815 * (This rule applies equally to all the synchronous transfer calls,
816 * which are wrappers around this core asynchronous primitive.)
818 int spi_async(struct spi_device *spi, struct spi_message *message)
820 struct spi_master *master = spi->master;
824 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
826 if (master->bus_lock_flag)
829 ret = __spi_async(spi, message);
831 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
835 EXPORT_SYMBOL_GPL(spi_async);
838 * spi_async_locked - version of spi_async with exclusive bus usage
839 * @spi: device with which data will be exchanged
840 * @message: describes the data transfers, including completion callback
841 * Context: any (irqs may be blocked, etc)
843 * This call may be used in_irq and other contexts which can't sleep,
844 * as well as from task contexts which can sleep.
846 * The completion callback is invoked in a context which can't sleep.
847 * Before that invocation, the value of message->status is undefined.
848 * When the callback is issued, message->status holds either zero (to
849 * indicate complete success) or a negative error code. After that
850 * callback returns, the driver which issued the transfer request may
851 * deallocate the associated memory; it's no longer in use by any SPI
852 * core or controller driver code.
854 * Note that although all messages to a spi_device are handled in
855 * FIFO order, messages may go to different devices in other orders.
856 * Some device might be higher priority, or have various "hard" access
857 * time requirements, for example.
859 * On detection of any fault during the transfer, processing of
860 * the entire message is aborted, and the device is deselected.
861 * Until returning from the associated message completion callback,
862 * no other spi_message queued to that device will be processed.
863 * (This rule applies equally to all the synchronous transfer calls,
864 * which are wrappers around this core asynchronous primitive.)
866 int spi_async_locked(struct spi_device *spi, struct spi_message *message)
868 struct spi_master *master = spi->master;
872 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
874 ret = __spi_async(spi, message);
876 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
881 EXPORT_SYMBOL_GPL(spi_async_locked);
884 /*-------------------------------------------------------------------------*/
886 /* Utility methods for SPI master protocol drivers, layered on
887 * top of the core. Some other utility methods are defined as
891 static void spi_complete(void *arg)
896 static int __spi_sync(struct spi_device *spi, struct spi_message *message,
899 DECLARE_COMPLETION_ONSTACK(done);
901 struct spi_master *master = spi->master;
903 message->complete = spi_complete;
904 message->context = &done;
907 mutex_lock(&master->bus_lock_mutex);
909 status = spi_async_locked(spi, message);
912 mutex_unlock(&master->bus_lock_mutex);
915 wait_for_completion(&done);
916 status = message->status;
918 message->context = NULL;
923 * spi_sync - blocking/synchronous SPI data transfers
924 * @spi: device with which data will be exchanged
925 * @message: describes the data transfers
928 * This call may only be used from a context that may sleep. The sleep
929 * is non-interruptible, and has no timeout. Low-overhead controller
930 * drivers may DMA directly into and out of the message buffers.
932 * Note that the SPI device's chip select is active during the message,
933 * and then is normally disabled between messages. Drivers for some
934 * frequently-used devices may want to minimize costs of selecting a chip,
935 * by leaving it selected in anticipation that the next message will go
936 * to the same chip. (That may increase power usage.)
938 * Also, the caller is guaranteeing that the memory associated with the
939 * message will not be freed before this call returns.
941 * It returns zero on success, else a negative error code.
943 int spi_sync(struct spi_device *spi, struct spi_message *message)
945 return __spi_sync(spi, message, 0);
947 EXPORT_SYMBOL_GPL(spi_sync);
950 * spi_sync_locked - version of spi_sync with exclusive bus usage
951 * @spi: device with which data will be exchanged
952 * @message: describes the data transfers
955 * This call may only be used from a context that may sleep. The sleep
956 * is non-interruptible, and has no timeout. Low-overhead controller
957 * drivers may DMA directly into and out of the message buffers.
959 * This call should be used by drivers that require exclusive access to the
960 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
961 * be released by a spi_bus_unlock call when the exclusive access is over.
963 * It returns zero on success, else a negative error code.
965 int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
967 return __spi_sync(spi, message, 1);
969 EXPORT_SYMBOL_GPL(spi_sync_locked);
972 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
973 * @master: SPI bus master that should be locked for exclusive bus access
976 * This call may only be used from a context that may sleep. The sleep
977 * is non-interruptible, and has no timeout.
979 * This call should be used by drivers that require exclusive access to the
980 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
981 * exclusive access is over. Data transfer must be done by spi_sync_locked
982 * and spi_async_locked calls when the SPI bus lock is held.
984 * It returns zero on success, else a negative error code.
986 int spi_bus_lock(struct spi_master *master)
990 mutex_lock(&master->bus_lock_mutex);
992 spin_lock_irqsave(&master->bus_lock_spinlock, flags);
993 master->bus_lock_flag = 1;
994 spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
996 /* mutex remains locked until spi_bus_unlock is called */
1000 EXPORT_SYMBOL_GPL(spi_bus_lock);
1003 * spi_bus_unlock - release the lock for exclusive SPI bus usage
1004 * @master: SPI bus master that was locked for exclusive bus access
1005 * Context: can sleep
1007 * This call may only be used from a context that may sleep. The sleep
1008 * is non-interruptible, and has no timeout.
1010 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
1013 * It returns zero on success, else a negative error code.
1015 int spi_bus_unlock(struct spi_master *master)
1017 master->bus_lock_flag = 0;
1019 mutex_unlock(&master->bus_lock_mutex);
1023 EXPORT_SYMBOL_GPL(spi_bus_unlock);
1025 /* portable code must never pass more than 32 bytes */
1026 #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
1031 * spi_write_then_read - SPI synchronous write followed by read
1032 * @spi: device with which data will be exchanged
1033 * @txbuf: data to be written (need not be dma-safe)
1034 * @n_tx: size of txbuf, in bytes
1035 * @rxbuf: buffer into which data will be read (need not be dma-safe)
1036 * @n_rx: size of rxbuf, in bytes
1037 * Context: can sleep
1039 * This performs a half duplex MicroWire style transaction with the
1040 * device, sending txbuf and then reading rxbuf. The return value
1041 * is zero for success, else a negative errno status code.
1042 * This call may only be used from a context that may sleep.
1044 * Parameters to this routine are always copied using a small buffer;
1045 * portable code should never use this for more than 32 bytes.
1046 * Performance-sensitive or bulk transfer code should instead use
1047 * spi_{async,sync}() calls with dma-safe buffers.
1049 int spi_write_then_read(struct spi_device *spi,
1050 const void *txbuf, unsigned n_tx,
1051 void *rxbuf, unsigned n_rx)
1053 static DEFINE_MUTEX(lock);
1056 struct spi_message message;
1057 struct spi_transfer x[2];
1060 /* Use preallocated DMA-safe buffer. We can't avoid copying here,
1061 * (as a pure convenience thing), but we can keep heap costs
1062 * out of the hot path ...
1064 if ((n_tx + n_rx) > SPI_BUFSIZ)
1067 spi_message_init(&message);
1068 memset(x, 0, sizeof x);
1071 spi_message_add_tail(&x[0], &message);
1075 spi_message_add_tail(&x[1], &message);
1078 /* ... unless someone else is using the pre-allocated buffer */
1079 if (!mutex_trylock(&lock)) {
1080 local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1086 memcpy(local_buf, txbuf, n_tx);
1087 x[0].tx_buf = local_buf;
1088 x[1].rx_buf = local_buf + n_tx;
1091 status = spi_sync(spi, &message);
1093 memcpy(rxbuf, x[1].rx_buf, n_rx);
1095 if (x[0].tx_buf == buf)
1096 mutex_unlock(&lock);
1102 EXPORT_SYMBOL_GPL(spi_write_then_read);
1104 /*-------------------------------------------------------------------------*/
1106 static int __init spi_init(void)
1110 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1116 status = bus_register(&spi_bus_type);
1120 status = class_register(&spi_master_class);
1126 bus_unregister(&spi_bus_type);
1134 /* board_info is normally registered in arch_initcall(),
1135 * but even essential drivers wait till later
1137 * REVISIT only boardinfo really needs static linking. the rest (device and
1138 * driver registration) _could_ be dynamically linked (modular) ... costs
1139 * include needing to have boardinfo data structures be much more public.
1141 postcore_initcall(spi_init);