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>
32 static void spidev_release(struct device
*dev
)
34 struct spi_device
*spi
= to_spi_device(dev
);
36 /* spi masters may cleanup for released devices */
37 if (spi
->master
->cleanup
)
38 spi
->master
->cleanup(spi
);
40 spi_master_put(spi
->master
);
45 modalias_show(struct device
*dev
, struct device_attribute
*a
, char *buf
)
47 const struct spi_device
*spi
= to_spi_device(dev
);
49 return sprintf(buf
, "%s\n", spi
->modalias
);
52 static struct device_attribute spi_dev_attrs
[] = {
57 /* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
58 * and the sysfs version makes coldplug work too.
61 static const struct spi_device_id
*spi_match_id(const struct spi_device_id
*id
,
62 const struct spi_device
*sdev
)
65 if (!strcmp(sdev
->modalias
, id
->name
))
72 const struct spi_device_id
*spi_get_device_id(const struct spi_device
*sdev
)
74 const struct spi_driver
*sdrv
= to_spi_driver(sdev
->dev
.driver
);
76 return spi_match_id(sdrv
->id_table
, sdev
);
78 EXPORT_SYMBOL_GPL(spi_get_device_id
);
80 static int spi_match_device(struct device
*dev
, struct device_driver
*drv
)
82 const struct spi_device
*spi
= to_spi_device(dev
);
83 const struct spi_driver
*sdrv
= to_spi_driver(drv
);
85 /* Attempt an OF style match */
86 if (of_driver_match_device(dev
, drv
))
90 return !!spi_match_id(sdrv
->id_table
, spi
);
92 return strcmp(spi
->modalias
, drv
->name
) == 0;
95 static int spi_uevent(struct device
*dev
, struct kobj_uevent_env
*env
)
97 const struct spi_device
*spi
= to_spi_device(dev
);
99 add_uevent_var(env
, "MODALIAS=%s%s", SPI_MODULE_PREFIX
, spi
->modalias
);
105 static int spi_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_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");
136 #define spi_suspend NULL
137 #define spi_resume NULL
140 struct bus_type spi_bus_type
= {
142 .dev_attrs
= spi_dev_attrs
,
143 .match
= spi_match_device
,
144 .uevent
= spi_uevent
,
145 .suspend
= spi_suspend
,
146 .resume
= spi_resume
,
148 EXPORT_SYMBOL_GPL(spi_bus_type
);
151 static int spi_drv_probe(struct device
*dev
)
153 const struct spi_driver
*sdrv
= to_spi_driver(dev
->driver
);
155 return sdrv
->probe(to_spi_device(dev
));
158 static int spi_drv_remove(struct device
*dev
)
160 const struct spi_driver
*sdrv
= to_spi_driver(dev
->driver
);
162 return sdrv
->remove(to_spi_device(dev
));
165 static void spi_drv_shutdown(struct device
*dev
)
167 const struct spi_driver
*sdrv
= to_spi_driver(dev
->driver
);
169 sdrv
->shutdown(to_spi_device(dev
));
173 * spi_register_driver - register a SPI driver
174 * @sdrv: the driver to register
177 int spi_register_driver(struct spi_driver
*sdrv
)
179 sdrv
->driver
.bus
= &spi_bus_type
;
181 sdrv
->driver
.probe
= spi_drv_probe
;
183 sdrv
->driver
.remove
= spi_drv_remove
;
185 sdrv
->driver
.shutdown
= spi_drv_shutdown
;
186 return driver_register(&sdrv
->driver
);
188 EXPORT_SYMBOL_GPL(spi_register_driver
);
190 /*-------------------------------------------------------------------------*/
192 /* SPI devices should normally not be created by SPI device drivers; that
193 * would make them board-specific. Similarly with SPI master drivers.
194 * Device registration normally goes into like arch/.../mach.../board-YYY.c
195 * with other readonly (flashable) information about mainboard devices.
199 struct list_head list
;
200 struct spi_board_info board_info
;
203 static LIST_HEAD(board_list
);
204 static LIST_HEAD(spi_master_list
);
207 * Used to protect add/del opertion for board_info list and
208 * spi_master list, and their matching process
210 static DEFINE_MUTEX(board_lock
);
213 * spi_alloc_device - Allocate a new SPI device
214 * @master: Controller to which device is connected
217 * Allows a driver to allocate and initialize a spi_device without
218 * registering it immediately. This allows a driver to directly
219 * fill the spi_device with device parameters before calling
220 * spi_add_device() on it.
222 * Caller is responsible to call spi_add_device() on the returned
223 * spi_device structure to add it to the SPI master. If the caller
224 * needs to discard the spi_device without adding it, then it should
225 * call spi_dev_put() on it.
227 * Returns a pointer to the new device, or NULL.
229 struct spi_device
*spi_alloc_device(struct spi_master
*master
)
231 struct spi_device
*spi
;
232 struct device
*dev
= master
->dev
.parent
;
234 if (!spi_master_get(master
))
237 spi
= kzalloc(sizeof *spi
, GFP_KERNEL
);
239 dev_err(dev
, "cannot alloc spi_device\n");
240 spi_master_put(master
);
244 spi
->master
= master
;
245 spi
->dev
.parent
= dev
;
246 spi
->dev
.bus
= &spi_bus_type
;
247 spi
->dev
.release
= spidev_release
;
248 device_initialize(&spi
->dev
);
251 EXPORT_SYMBOL_GPL(spi_alloc_device
);
254 * spi_add_device - Add spi_device allocated with spi_alloc_device
255 * @spi: spi_device to register
257 * Companion function to spi_alloc_device. Devices allocated with
258 * spi_alloc_device can be added onto the spi bus with this function.
260 * Returns 0 on success; negative errno on failure
262 int spi_add_device(struct spi_device
*spi
)
264 static DEFINE_MUTEX(spi_add_lock
);
265 struct device
*dev
= spi
->master
->dev
.parent
;
269 /* Chipselects are numbered 0..max; validate. */
270 if (spi
->chip_select
>= spi
->master
->num_chipselect
) {
271 dev_err(dev
, "cs%d >= max %d\n",
273 spi
->master
->num_chipselect
);
277 /* Set the bus ID string */
278 dev_set_name(&spi
->dev
, "%s.%u", dev_name(&spi
->master
->dev
),
282 /* We need to make sure there's no other device with this
283 * chipselect **BEFORE** we call setup(), else we'll trash
284 * its configuration. Lock against concurrent add() calls.
286 mutex_lock(&spi_add_lock
);
288 d
= bus_find_device_by_name(&spi_bus_type
, NULL
, dev_name(&spi
->dev
));
290 dev_err(dev
, "chipselect %d already in use\n",
297 /* Drivers may modify this initial i/o setup, but will
298 * normally rely on the device being setup. Devices
299 * using SPI_CS_HIGH can't coexist well otherwise...
301 status
= spi_setup(spi
);
303 dev_err(dev
, "can't setup %s, status %d\n",
304 dev_name(&spi
->dev
), status
);
308 /* Device may be bound to an active driver when this returns */
309 status
= device_add(&spi
->dev
);
311 dev_err(dev
, "can't add %s, status %d\n",
312 dev_name(&spi
->dev
), status
);
314 dev_dbg(dev
, "registered child %s\n", dev_name(&spi
->dev
));
317 mutex_unlock(&spi_add_lock
);
320 EXPORT_SYMBOL_GPL(spi_add_device
);
323 * spi_new_device - instantiate one new SPI device
324 * @master: Controller to which device is connected
325 * @chip: Describes the SPI device
328 * On typical mainboards, this is purely internal; and it's not needed
329 * after board init creates the hard-wired devices. Some development
330 * platforms may not be able to use spi_register_board_info though, and
331 * this is exported so that for example a USB or parport based adapter
332 * driver could add devices (which it would learn about out-of-band).
334 * Returns the new device, or NULL.
336 struct spi_device
*spi_new_device(struct spi_master
*master
,
337 struct spi_board_info
*chip
)
339 struct spi_device
*proxy
;
342 /* NOTE: caller did any chip->bus_num checks necessary.
344 * Also, unless we change the return value convention to use
345 * error-or-pointer (not NULL-or-pointer), troubleshootability
346 * suggests syslogged diagnostics are best here (ugh).
349 proxy
= spi_alloc_device(master
);
353 WARN_ON(strlen(chip
->modalias
) >= sizeof(proxy
->modalias
));
355 proxy
->chip_select
= chip
->chip_select
;
356 proxy
->max_speed_hz
= chip
->max_speed_hz
;
357 proxy
->mode
= chip
->mode
;
358 proxy
->irq
= chip
->irq
;
359 strlcpy(proxy
->modalias
, chip
->modalias
, sizeof(proxy
->modalias
));
360 proxy
->dev
.platform_data
= (void *) chip
->platform_data
;
361 proxy
->controller_data
= chip
->controller_data
;
362 proxy
->controller_state
= NULL
;
364 status
= spi_add_device(proxy
);
372 EXPORT_SYMBOL_GPL(spi_new_device
);
374 static void spi_match_master_to_boardinfo(struct spi_master
*master
,
375 struct spi_board_info
*bi
)
377 struct spi_device
*dev
;
379 if (master
->bus_num
!= bi
->bus_num
)
382 dev
= spi_new_device(master
, bi
);
384 dev_err(master
->dev
.parent
, "can't create new device for %s\n",
389 * spi_register_board_info - register SPI devices for a given board
390 * @info: array of chip descriptors
391 * @n: how many descriptors are provided
394 * Board-specific early init code calls this (probably during arch_initcall)
395 * with segments of the SPI device table. Any device nodes are created later,
396 * after the relevant parent SPI controller (bus_num) is defined. We keep
397 * this table of devices forever, so that reloading a controller driver will
398 * not make Linux forget about these hard-wired devices.
400 * Other code can also call this, e.g. a particular add-on board might provide
401 * SPI devices through its expansion connector, so code initializing that board
402 * would naturally declare its SPI devices.
404 * The board info passed can safely be __initdata ... but be careful of
405 * any embedded pointers (platform_data, etc), they're copied as-is.
408 spi_register_board_info(struct spi_board_info
const *info
, unsigned n
)
410 struct boardinfo
*bi
;
413 bi
= kzalloc(n
* sizeof(*bi
), GFP_KERNEL
);
417 for (i
= 0; i
< n
; i
++, bi
++, info
++) {
418 struct spi_master
*master
;
420 memcpy(&bi
->board_info
, info
, sizeof(*info
));
421 mutex_lock(&board_lock
);
422 list_add_tail(&bi
->list
, &board_list
);
423 list_for_each_entry(master
, &spi_master_list
, list
)
424 spi_match_master_to_boardinfo(master
, &bi
->board_info
);
425 mutex_unlock(&board_lock
);
431 /*-------------------------------------------------------------------------*/
433 static void spi_master_release(struct device
*dev
)
435 struct spi_master
*master
;
437 master
= container_of(dev
, struct spi_master
, dev
);
441 static struct class spi_master_class
= {
442 .name
= "spi_master",
443 .owner
= THIS_MODULE
,
444 .dev_release
= spi_master_release
,
449 * spi_alloc_master - allocate SPI master controller
450 * @dev: the controller, possibly using the platform_bus
451 * @size: how much zeroed driver-private data to allocate; the pointer to this
452 * memory is in the driver_data field of the returned device,
453 * accessible with spi_master_get_devdata().
456 * This call is used only by SPI master controller drivers, which are the
457 * only ones directly touching chip registers. It's how they allocate
458 * an spi_master structure, prior to calling spi_register_master().
460 * This must be called from context that can sleep. It returns the SPI
461 * master structure on success, else NULL.
463 * The caller is responsible for assigning the bus number and initializing
464 * the master's methods before calling spi_register_master(); and (after errors
465 * adding the device) calling spi_master_put() to prevent a memory leak.
467 struct spi_master
*spi_alloc_master(struct device
*dev
, unsigned size
)
469 struct spi_master
*master
;
474 master
= kzalloc(size
+ sizeof *master
, GFP_KERNEL
);
478 device_initialize(&master
->dev
);
479 master
->dev
.class = &spi_master_class
;
480 master
->dev
.parent
= get_device(dev
);
481 spi_master_set_devdata(master
, &master
[1]);
485 EXPORT_SYMBOL_GPL(spi_alloc_master
);
488 * spi_register_master - register SPI master controller
489 * @master: initialized master, originally from spi_alloc_master()
492 * SPI master controllers connect to their drivers using some non-SPI bus,
493 * such as the platform bus. The final stage of probe() in that code
494 * includes calling spi_register_master() to hook up to this SPI bus glue.
496 * SPI controllers use board specific (often SOC specific) bus numbers,
497 * and board-specific addressing for SPI devices combines those numbers
498 * with chip select numbers. Since SPI does not directly support dynamic
499 * device identification, boards need configuration tables telling which
500 * chip is at which address.
502 * This must be called from context that can sleep. It returns zero on
503 * success, else a negative error code (dropping the master's refcount).
504 * After a successful return, the caller is responsible for calling
505 * spi_unregister_master().
507 int spi_register_master(struct spi_master
*master
)
509 static atomic_t dyn_bus_id
= ATOMIC_INIT((1<<15) - 1);
510 struct device
*dev
= master
->dev
.parent
;
511 struct boardinfo
*bi
;
512 int status
= -ENODEV
;
518 /* even if it's just one always-selected device, there must
519 * be at least one chipselect
521 if (master
->num_chipselect
== 0)
524 /* convention: dynamically assigned bus IDs count down from the max */
525 if (master
->bus_num
< 0) {
526 /* FIXME switch to an IDR based scheme, something like
527 * I2C now uses, so we can't run out of "dynamic" IDs
529 master
->bus_num
= atomic_dec_return(&dyn_bus_id
);
533 spin_lock_init(&master
->bus_lock_spinlock
);
534 mutex_init(&master
->bus_lock_mutex
);
535 master
->bus_lock_flag
= 0;
537 /* register the device, then userspace will see it.
538 * registration fails if the bus ID is in use.
540 dev_set_name(&master
->dev
, "spi%u", master
->bus_num
);
541 status
= device_add(&master
->dev
);
544 dev_dbg(dev
, "registered master %s%s\n", dev_name(&master
->dev
),
545 dynamic
? " (dynamic)" : "");
547 mutex_lock(&board_lock
);
548 list_add_tail(&master
->list
, &spi_master_list
);
549 list_for_each_entry(bi
, &board_list
, list
)
550 spi_match_master_to_boardinfo(master
, &bi
->board_info
);
551 mutex_unlock(&board_lock
);
555 /* Register devices from the device tree */
556 of_register_spi_devices(master
);
560 EXPORT_SYMBOL_GPL(spi_register_master
);
563 static int __unregister(struct device
*dev
, void *null
)
565 spi_unregister_device(to_spi_device(dev
));
570 * spi_unregister_master - unregister SPI master controller
571 * @master: the master being unregistered
574 * This call is used only by SPI master controller drivers, which are the
575 * only ones directly touching chip registers.
577 * This must be called from context that can sleep.
579 void spi_unregister_master(struct spi_master
*master
)
583 mutex_lock(&board_lock
);
584 list_del(&master
->list
);
585 mutex_unlock(&board_lock
);
587 dummy
= device_for_each_child(&master
->dev
, NULL
, __unregister
);
588 device_unregister(&master
->dev
);
590 EXPORT_SYMBOL_GPL(spi_unregister_master
);
592 static int __spi_master_match(struct device
*dev
, void *data
)
594 struct spi_master
*m
;
597 m
= container_of(dev
, struct spi_master
, dev
);
598 return m
->bus_num
== *bus_num
;
602 * spi_busnum_to_master - look up master associated with bus_num
603 * @bus_num: the master's bus number
606 * This call may be used with devices that are registered after
607 * arch init time. It returns a refcounted pointer to the relevant
608 * spi_master (which the caller must release), or NULL if there is
609 * no such master registered.
611 struct spi_master
*spi_busnum_to_master(u16 bus_num
)
614 struct spi_master
*master
= NULL
;
616 dev
= class_find_device(&spi_master_class
, NULL
, &bus_num
,
619 master
= container_of(dev
, struct spi_master
, dev
);
620 /* reference got in class_find_device */
623 EXPORT_SYMBOL_GPL(spi_busnum_to_master
);
626 /*-------------------------------------------------------------------------*/
628 /* Core methods for SPI master protocol drivers. Some of the
629 * other core methods are currently defined as inline functions.
633 * spi_setup - setup SPI mode and clock rate
634 * @spi: the device whose settings are being modified
635 * Context: can sleep, and no requests are queued to the device
637 * SPI protocol drivers may need to update the transfer mode if the
638 * device doesn't work with its default. They may likewise need
639 * to update clock rates or word sizes from initial values. This function
640 * changes those settings, and must be called from a context that can sleep.
641 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
642 * effect the next time the device is selected and data is transferred to
643 * or from it. When this function returns, the spi device is deselected.
645 * Note that this call will fail if the protocol driver specifies an option
646 * that the underlying controller or its driver does not support. For
647 * example, not all hardware supports wire transfers using nine bit words,
648 * LSB-first wire encoding, or active-high chipselects.
650 int spi_setup(struct spi_device
*spi
)
655 /* help drivers fail *cleanly* when they need options
656 * that aren't supported with their current master
658 bad_bits
= spi
->mode
& ~spi
->master
->mode_bits
;
660 dev_err(&spi
->dev
, "setup: unsupported mode bits %x\n",
665 if (!spi
->bits_per_word
)
666 spi
->bits_per_word
= 8;
668 status
= spi
->master
->setup(spi
);
670 dev_dbg(&spi
->dev
, "setup mode %d, %s%s%s%s"
671 "%u bits/w, %u Hz max --> %d\n",
672 (int) (spi
->mode
& (SPI_CPOL
| SPI_CPHA
)),
673 (spi
->mode
& SPI_CS_HIGH
) ? "cs_high, " : "",
674 (spi
->mode
& SPI_LSB_FIRST
) ? "lsb, " : "",
675 (spi
->mode
& SPI_3WIRE
) ? "3wire, " : "",
676 (spi
->mode
& SPI_LOOP
) ? "loopback, " : "",
677 spi
->bits_per_word
, spi
->max_speed_hz
,
682 EXPORT_SYMBOL_GPL(spi_setup
);
684 static int __spi_async(struct spi_device
*spi
, struct spi_message
*message
)
686 struct spi_master
*master
= spi
->master
;
688 /* Half-duplex links include original MicroWire, and ones with
689 * only one data pin like SPI_3WIRE (switches direction) or where
690 * either MOSI or MISO is missing. They can also be caused by
691 * software limitations.
693 if ((master
->flags
& SPI_MASTER_HALF_DUPLEX
)
694 || (spi
->mode
& SPI_3WIRE
)) {
695 struct spi_transfer
*xfer
;
696 unsigned flags
= master
->flags
;
698 list_for_each_entry(xfer
, &message
->transfers
, transfer_list
) {
699 if (xfer
->rx_buf
&& xfer
->tx_buf
)
701 if ((flags
& SPI_MASTER_NO_TX
) && xfer
->tx_buf
)
703 if ((flags
& SPI_MASTER_NO_RX
) && xfer
->rx_buf
)
709 message
->status
= -EINPROGRESS
;
710 return master
->transfer(spi
, message
);
714 * spi_async - asynchronous SPI transfer
715 * @spi: device with which data will be exchanged
716 * @message: describes the data transfers, including completion callback
717 * Context: any (irqs may be blocked, etc)
719 * This call may be used in_irq and other contexts which can't sleep,
720 * as well as from task contexts which can sleep.
722 * The completion callback is invoked in a context which can't sleep.
723 * Before that invocation, the value of message->status is undefined.
724 * When the callback is issued, message->status holds either zero (to
725 * indicate complete success) or a negative error code. After that
726 * callback returns, the driver which issued the transfer request may
727 * deallocate the associated memory; it's no longer in use by any SPI
728 * core or controller driver code.
730 * Note that although all messages to a spi_device are handled in
731 * FIFO order, messages may go to different devices in other orders.
732 * Some device might be higher priority, or have various "hard" access
733 * time requirements, for example.
735 * On detection of any fault during the transfer, processing of
736 * the entire message is aborted, and the device is deselected.
737 * Until returning from the associated message completion callback,
738 * no other spi_message queued to that device will be processed.
739 * (This rule applies equally to all the synchronous transfer calls,
740 * which are wrappers around this core asynchronous primitive.)
742 int spi_async(struct spi_device
*spi
, struct spi_message
*message
)
744 struct spi_master
*master
= spi
->master
;
748 spin_lock_irqsave(&master
->bus_lock_spinlock
, flags
);
750 if (master
->bus_lock_flag
)
753 ret
= __spi_async(spi
, message
);
755 spin_unlock_irqrestore(&master
->bus_lock_spinlock
, flags
);
759 EXPORT_SYMBOL_GPL(spi_async
);
762 * spi_async_locked - version of spi_async with exclusive bus usage
763 * @spi: device with which data will be exchanged
764 * @message: describes the data transfers, including completion callback
765 * Context: any (irqs may be blocked, etc)
767 * This call may be used in_irq and other contexts which can't sleep,
768 * as well as from task contexts which can sleep.
770 * The completion callback is invoked in a context which can't sleep.
771 * Before that invocation, the value of message->status is undefined.
772 * When the callback is issued, message->status holds either zero (to
773 * indicate complete success) or a negative error code. After that
774 * callback returns, the driver which issued the transfer request may
775 * deallocate the associated memory; it's no longer in use by any SPI
776 * core or controller driver code.
778 * Note that although all messages to a spi_device are handled in
779 * FIFO order, messages may go to different devices in other orders.
780 * Some device might be higher priority, or have various "hard" access
781 * time requirements, for example.
783 * On detection of any fault during the transfer, processing of
784 * the entire message is aborted, and the device is deselected.
785 * Until returning from the associated message completion callback,
786 * no other spi_message queued to that device will be processed.
787 * (This rule applies equally to all the synchronous transfer calls,
788 * which are wrappers around this core asynchronous primitive.)
790 int spi_async_locked(struct spi_device
*spi
, struct spi_message
*message
)
792 struct spi_master
*master
= spi
->master
;
796 spin_lock_irqsave(&master
->bus_lock_spinlock
, flags
);
798 ret
= __spi_async(spi
, message
);
800 spin_unlock_irqrestore(&master
->bus_lock_spinlock
, flags
);
805 EXPORT_SYMBOL_GPL(spi_async_locked
);
808 /*-------------------------------------------------------------------------*/
810 /* Utility methods for SPI master protocol drivers, layered on
811 * top of the core. Some other utility methods are defined as
815 static void spi_complete(void *arg
)
820 static int __spi_sync(struct spi_device
*spi
, struct spi_message
*message
,
823 DECLARE_COMPLETION_ONSTACK(done
);
825 struct spi_master
*master
= spi
->master
;
827 message
->complete
= spi_complete
;
828 message
->context
= &done
;
831 mutex_lock(&master
->bus_lock_mutex
);
833 status
= spi_async_locked(spi
, message
);
836 mutex_unlock(&master
->bus_lock_mutex
);
839 wait_for_completion(&done
);
840 status
= message
->status
;
842 message
->context
= NULL
;
847 * spi_sync - blocking/synchronous SPI data transfers
848 * @spi: device with which data will be exchanged
849 * @message: describes the data transfers
852 * This call may only be used from a context that may sleep. The sleep
853 * is non-interruptible, and has no timeout. Low-overhead controller
854 * drivers may DMA directly into and out of the message buffers.
856 * Note that the SPI device's chip select is active during the message,
857 * and then is normally disabled between messages. Drivers for some
858 * frequently-used devices may want to minimize costs of selecting a chip,
859 * by leaving it selected in anticipation that the next message will go
860 * to the same chip. (That may increase power usage.)
862 * Also, the caller is guaranteeing that the memory associated with the
863 * message will not be freed before this call returns.
865 * It returns zero on success, else a negative error code.
867 int spi_sync(struct spi_device
*spi
, struct spi_message
*message
)
869 return __spi_sync(spi
, message
, 0);
871 EXPORT_SYMBOL_GPL(spi_sync
);
874 * spi_sync_locked - version of spi_sync with exclusive bus usage
875 * @spi: device with which data will be exchanged
876 * @message: describes the data transfers
879 * This call may only be used from a context that may sleep. The sleep
880 * is non-interruptible, and has no timeout. Low-overhead controller
881 * drivers may DMA directly into and out of the message buffers.
883 * This call should be used by drivers that require exclusive access to the
884 * SPI bus. It has to be preceeded by a spi_bus_lock call. The SPI bus must
885 * be released by a spi_bus_unlock call when the exclusive access is over.
887 * It returns zero on success, else a negative error code.
889 int spi_sync_locked(struct spi_device
*spi
, struct spi_message
*message
)
891 return __spi_sync(spi
, message
, 1);
893 EXPORT_SYMBOL_GPL(spi_sync_locked
);
896 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
897 * @master: SPI bus master that should be locked for exclusive bus access
900 * This call may only be used from a context that may sleep. The sleep
901 * is non-interruptible, and has no timeout.
903 * This call should be used by drivers that require exclusive access to the
904 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
905 * exclusive access is over. Data transfer must be done by spi_sync_locked
906 * and spi_async_locked calls when the SPI bus lock is held.
908 * It returns zero on success, else a negative error code.
910 int spi_bus_lock(struct spi_master
*master
)
914 mutex_lock(&master
->bus_lock_mutex
);
916 spin_lock_irqsave(&master
->bus_lock_spinlock
, flags
);
917 master
->bus_lock_flag
= 1;
918 spin_unlock_irqrestore(&master
->bus_lock_spinlock
, flags
);
920 /* mutex remains locked until spi_bus_unlock is called */
924 EXPORT_SYMBOL_GPL(spi_bus_lock
);
927 * spi_bus_unlock - release the lock for exclusive SPI bus usage
928 * @master: SPI bus master that was locked for exclusive bus access
931 * This call may only be used from a context that may sleep. The sleep
932 * is non-interruptible, and has no timeout.
934 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
937 * It returns zero on success, else a negative error code.
939 int spi_bus_unlock(struct spi_master
*master
)
941 master
->bus_lock_flag
= 0;
943 mutex_unlock(&master
->bus_lock_mutex
);
947 EXPORT_SYMBOL_GPL(spi_bus_unlock
);
949 /* portable code must never pass more than 32 bytes */
950 #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
955 * spi_write_then_read - SPI synchronous write followed by read
956 * @spi: device with which data will be exchanged
957 * @txbuf: data to be written (need not be dma-safe)
958 * @n_tx: size of txbuf, in bytes
959 * @rxbuf: buffer into which data will be read (need not be dma-safe)
960 * @n_rx: size of rxbuf, in bytes
963 * This performs a half duplex MicroWire style transaction with the
964 * device, sending txbuf and then reading rxbuf. The return value
965 * is zero for success, else a negative errno status code.
966 * This call may only be used from a context that may sleep.
968 * Parameters to this routine are always copied using a small buffer;
969 * portable code should never use this for more than 32 bytes.
970 * Performance-sensitive or bulk transfer code should instead use
971 * spi_{async,sync}() calls with dma-safe buffers.
973 int spi_write_then_read(struct spi_device
*spi
,
974 const u8
*txbuf
, unsigned n_tx
,
975 u8
*rxbuf
, unsigned n_rx
)
977 static DEFINE_MUTEX(lock
);
980 struct spi_message message
;
981 struct spi_transfer x
[2];
984 /* Use preallocated DMA-safe buffer. We can't avoid copying here,
985 * (as a pure convenience thing), but we can keep heap costs
986 * out of the hot path ...
988 if ((n_tx
+ n_rx
) > SPI_BUFSIZ
)
991 spi_message_init(&message
);
992 memset(x
, 0, sizeof x
);
995 spi_message_add_tail(&x
[0], &message
);
999 spi_message_add_tail(&x
[1], &message
);
1002 /* ... unless someone else is using the pre-allocated buffer */
1003 if (!mutex_trylock(&lock
)) {
1004 local_buf
= kmalloc(SPI_BUFSIZ
, GFP_KERNEL
);
1010 memcpy(local_buf
, txbuf
, n_tx
);
1011 x
[0].tx_buf
= local_buf
;
1012 x
[1].rx_buf
= local_buf
+ n_tx
;
1015 status
= spi_sync(spi
, &message
);
1017 memcpy(rxbuf
, x
[1].rx_buf
, n_rx
);
1019 if (x
[0].tx_buf
== buf
)
1020 mutex_unlock(&lock
);
1026 EXPORT_SYMBOL_GPL(spi_write_then_read
);
1028 /*-------------------------------------------------------------------------*/
1030 static int __init
spi_init(void)
1034 buf
= kmalloc(SPI_BUFSIZ
, GFP_KERNEL
);
1040 status
= bus_register(&spi_bus_type
);
1044 status
= class_register(&spi_master_class
);
1050 bus_unregister(&spi_bus_type
);
1058 /* board_info is normally registered in arch_initcall(),
1059 * but even essential drivers wait till later
1061 * REVISIT only boardinfo really needs static linking. the rest (device and
1062 * driver registration) _could_ be dynamically linked (modular) ... costs
1063 * include needing to have boardinfo data structures be much more public.
1065 postcore_initcall(spi_init
);