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/slab.h>
27 #include <linux/mod_devicetable.h>
28 #include <linux/spi/spi.h>
31 /* SPI bustype and spi_master class are registered after board init code
32 * provides the SPI device tables, ensuring that both are present by the
33 * time controller driver registration causes spi_devices to "enumerate".
35 static void spidev_release(struct device *dev)
37 struct spi_device *spi = to_spi_device(dev);
39 /* spi masters may cleanup for released devices */
40 if (spi->master->cleanup)
41 spi->master->cleanup(spi);
43 spi_master_put(spi->master);
48 modalias_show(struct device *dev, struct device_attribute *a, char *buf)
50 const struct spi_device *spi = to_spi_device(dev);
52 return sprintf(buf, "%s\n", spi->modalias);
55 static struct device_attribute spi_dev_attrs[] = {
60 /* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
61 * and the sysfs version makes coldplug work too.
64 static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
65 const struct spi_device *sdev)
68 if (!strcmp(sdev->modalias, id->name))
75 const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
77 const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
79 return spi_match_id(sdrv->id_table, sdev);
81 EXPORT_SYMBOL_GPL(spi_get_device_id);
83 static int spi_match_device(struct device *dev, struct device_driver *drv)
85 const struct spi_device *spi = to_spi_device(dev);
86 const struct spi_driver *sdrv = to_spi_driver(drv);
89 return !!spi_match_id(sdrv->id_table, spi);
91 return strcmp(spi->modalias, drv->name) == 0;
94 static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
96 const struct spi_device *spi = to_spi_device(dev);
98 add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
104 static int spi_suspend(struct device *dev, pm_message_t message)
107 struct spi_driver *drv = to_spi_driver(dev->driver);
109 /* suspend will stop irqs and dma; no more i/o */
112 value = drv->suspend(to_spi_device(dev), message);
114 dev_dbg(dev, "... can't suspend\n");
119 static int spi_resume(struct device *dev)
122 struct spi_driver *drv = to_spi_driver(dev->driver);
124 /* resume may restart the i/o queue */
127 value = drv->resume(to_spi_device(dev));
129 dev_dbg(dev, "... can't resume\n");
135 #define spi_suspend NULL
136 #define spi_resume NULL
139 struct bus_type spi_bus_type = {
141 .dev_attrs = spi_dev_attrs,
142 .match = spi_match_device,
143 .uevent = spi_uevent,
144 .suspend = spi_suspend,
145 .resume = spi_resume,
147 EXPORT_SYMBOL_GPL(spi_bus_type);
150 static int spi_drv_probe(struct device *dev)
152 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
154 return sdrv->probe(to_spi_device(dev));
157 static int spi_drv_remove(struct device *dev)
159 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
161 return sdrv->remove(to_spi_device(dev));
164 static void spi_drv_shutdown(struct device *dev)
166 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
168 sdrv->shutdown(to_spi_device(dev));
172 * spi_register_driver - register a SPI driver
173 * @sdrv: the driver to register
176 int spi_register_driver(struct spi_driver *sdrv)
178 sdrv->driver.bus = &spi_bus_type;
180 sdrv->driver.probe = spi_drv_probe;
182 sdrv->driver.remove = spi_drv_remove;
184 sdrv->driver.shutdown = spi_drv_shutdown;
185 return driver_register(&sdrv->driver);
187 EXPORT_SYMBOL_GPL(spi_register_driver);
189 /*-------------------------------------------------------------------------*/
191 /* SPI devices should normally not be created by SPI device drivers; that
192 * would make them board-specific. Similarly with SPI master drivers.
193 * Device registration normally goes into like arch/.../mach.../board-YYY.c
194 * with other readonly (flashable) information about mainboard devices.
198 struct list_head list;
199 unsigned n_board_info;
200 struct spi_board_info board_info[0];
203 static LIST_HEAD(board_list);
204 static DEFINE_MUTEX(board_lock);
207 * spi_alloc_device - Allocate a new SPI device
208 * @master: Controller to which device is connected
211 * Allows a driver to allocate and initialize a spi_device without
212 * registering it immediately. This allows a driver to directly
213 * fill the spi_device with device parameters before calling
214 * spi_add_device() on it.
216 * Caller is responsible to call spi_add_device() on the returned
217 * spi_device structure to add it to the SPI master. If the caller
218 * needs to discard the spi_device without adding it, then it should
219 * call spi_dev_put() on it.
221 * Returns a pointer to the new device, or NULL.
223 struct spi_device *spi_alloc_device(struct spi_master *master)
225 struct spi_device *spi;
226 struct device *dev = master->dev.parent;
228 if (!spi_master_get(master))
231 spi = kzalloc(sizeof *spi, GFP_KERNEL);
233 dev_err(dev, "cannot alloc spi_device\n");
234 spi_master_put(master);
238 spi->master = master;
239 spi->dev.parent = dev;
240 spi->dev.bus = &spi_bus_type;
241 spi->dev.release = spidev_release;
242 device_initialize(&spi->dev);
245 EXPORT_SYMBOL_GPL(spi_alloc_device);
248 * spi_add_device - Add spi_device allocated with spi_alloc_device
249 * @spi: spi_device to register
251 * Companion function to spi_alloc_device. Devices allocated with
252 * spi_alloc_device can be added onto the spi bus with this function.
254 * Returns 0 on success; negative errno on failure
256 int spi_add_device(struct spi_device *spi)
258 static DEFINE_MUTEX(spi_add_lock);
259 struct device *dev = spi->master->dev.parent;
262 /* Chipselects are numbered 0..max; validate. */
263 if (spi->chip_select >= spi->master->num_chipselect) {
264 dev_err(dev, "cs%d >= max %d\n",
266 spi->master->num_chipselect);
270 /* Set the bus ID string */
271 dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
275 /* We need to make sure there's no other device with this
276 * chipselect **BEFORE** we call setup(), else we'll trash
277 * its configuration. Lock against concurrent add() calls.
279 mutex_lock(&spi_add_lock);
281 if (bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev))
283 dev_err(dev, "chipselect %d already in use\n",
289 /* Drivers may modify this initial i/o setup, but will
290 * normally rely on the device being setup. Devices
291 * using SPI_CS_HIGH can't coexist well otherwise...
293 status = spi_setup(spi);
295 dev_err(dev, "can't %s %s, status %d\n",
296 "setup", dev_name(&spi->dev), status);
300 /* Device may be bound to an active driver when this returns */
301 status = device_add(&spi->dev);
303 dev_err(dev, "can't %s %s, status %d\n",
304 "add", dev_name(&spi->dev), status);
306 dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
309 mutex_unlock(&spi_add_lock);
312 EXPORT_SYMBOL_GPL(spi_add_device);
315 * spi_new_device - instantiate one new SPI device
316 * @master: Controller to which device is connected
317 * @chip: Describes the SPI device
320 * On typical mainboards, this is purely internal; and it's not needed
321 * after board init creates the hard-wired devices. Some development
322 * platforms may not be able to use spi_register_board_info though, and
323 * this is exported so that for example a USB or parport based adapter
324 * driver could add devices (which it would learn about out-of-band).
326 * Returns the new device, or NULL.
328 struct spi_device *spi_new_device(struct spi_master *master,
329 struct spi_board_info *chip)
331 struct spi_device *proxy;
334 /* NOTE: caller did any chip->bus_num checks necessary.
336 * Also, unless we change the return value convention to use
337 * error-or-pointer (not NULL-or-pointer), troubleshootability
338 * suggests syslogged diagnostics are best here (ugh).
341 proxy = spi_alloc_device(master);
345 WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
347 proxy->chip_select = chip->chip_select;
348 proxy->max_speed_hz = chip->max_speed_hz;
349 proxy->mode = chip->mode;
350 proxy->irq = chip->irq;
351 strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
352 proxy->dev.platform_data = (void *) chip->platform_data;
353 proxy->controller_data = chip->controller_data;
354 proxy->controller_state = NULL;
356 status = spi_add_device(proxy);
364 EXPORT_SYMBOL_GPL(spi_new_device);
367 * spi_register_board_info - register SPI devices for a given board
368 * @info: array of chip descriptors
369 * @n: how many descriptors are provided
372 * Board-specific early init code calls this (probably during arch_initcall)
373 * with segments of the SPI device table. Any device nodes are created later,
374 * after the relevant parent SPI controller (bus_num) is defined. We keep
375 * this table of devices forever, so that reloading a controller driver will
376 * not make Linux forget about these hard-wired devices.
378 * Other code can also call this, e.g. a particular add-on board might provide
379 * SPI devices through its expansion connector, so code initializing that board
380 * would naturally declare its SPI devices.
382 * The board info passed can safely be __initdata ... but be careful of
383 * any embedded pointers (platform_data, etc), they're copied as-is.
386 spi_register_board_info(struct spi_board_info const *info, unsigned n)
388 struct boardinfo *bi;
390 bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL);
393 bi->n_board_info = n;
394 memcpy(bi->board_info, info, n * sizeof *info);
396 mutex_lock(&board_lock);
397 list_add_tail(&bi->list, &board_list);
398 mutex_unlock(&board_lock);
402 /* FIXME someone should add support for a __setup("spi", ...) that
403 * creates board info from kernel command lines
406 static void scan_boardinfo(struct spi_master *master)
408 struct boardinfo *bi;
410 mutex_lock(&board_lock);
411 list_for_each_entry(bi, &board_list, list) {
412 struct spi_board_info *chip = bi->board_info;
415 for (n = bi->n_board_info; n > 0; n--, chip++) {
416 if (chip->bus_num != master->bus_num)
418 /* NOTE: this relies on spi_new_device to
419 * issue diagnostics when given bogus inputs
421 (void) spi_new_device(master, chip);
424 mutex_unlock(&board_lock);
427 /*-------------------------------------------------------------------------*/
429 static void spi_master_release(struct device *dev)
431 struct spi_master *master;
433 master = container_of(dev, struct spi_master, dev);
437 static struct class spi_master_class = {
438 .name = "spi_master",
439 .owner = THIS_MODULE,
440 .dev_release = spi_master_release,
445 * spi_alloc_master - allocate SPI master controller
446 * @dev: the controller, possibly using the platform_bus
447 * @size: how much zeroed driver-private data to allocate; the pointer to this
448 * memory is in the driver_data field of the returned device,
449 * accessible with spi_master_get_devdata().
452 * This call is used only by SPI master controller drivers, which are the
453 * only ones directly touching chip registers. It's how they allocate
454 * an spi_master structure, prior to calling spi_register_master().
456 * This must be called from context that can sleep. It returns the SPI
457 * master structure on success, else NULL.
459 * The caller is responsible for assigning the bus number and initializing
460 * the master's methods before calling spi_register_master(); and (after errors
461 * adding the device) calling spi_master_put() to prevent a memory leak.
463 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
465 struct spi_master *master;
470 master = kzalloc(size + sizeof *master, GFP_KERNEL);
474 device_initialize(&master->dev);
475 master->dev.class = &spi_master_class;
476 master->dev.parent = get_device(dev);
477 spi_master_set_devdata(master, &master[1]);
481 EXPORT_SYMBOL_GPL(spi_alloc_master);
484 * spi_register_master - register SPI master controller
485 * @master: initialized master, originally from spi_alloc_master()
488 * SPI master controllers connect to their drivers using some non-SPI bus,
489 * such as the platform bus. The final stage of probe() in that code
490 * includes calling spi_register_master() to hook up to this SPI bus glue.
492 * SPI controllers use board specific (often SOC specific) bus numbers,
493 * and board-specific addressing for SPI devices combines those numbers
494 * with chip select numbers. Since SPI does not directly support dynamic
495 * device identification, boards need configuration tables telling which
496 * chip is at which address.
498 * This must be called from context that can sleep. It returns zero on
499 * success, else a negative error code (dropping the master's refcount).
500 * After a successful return, the caller is responsible for calling
501 * spi_unregister_master().
503 int spi_register_master(struct spi_master *master)
505 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
506 struct device *dev = master->dev.parent;
507 int status = -ENODEV;
513 /* even if it's just one always-selected device, there must
514 * be at least one chipselect
516 if (master->num_chipselect == 0)
519 /* convention: dynamically assigned bus IDs count down from the max */
520 if (master->bus_num < 0) {
521 /* FIXME switch to an IDR based scheme, something like
522 * I2C now uses, so we can't run out of "dynamic" IDs
524 master->bus_num = atomic_dec_return(&dyn_bus_id);
528 /* register the device, then userspace will see it.
529 * registration fails if the bus ID is in use.
531 dev_set_name(&master->dev, "spi%u", master->bus_num);
532 status = device_add(&master->dev);
535 dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
536 dynamic ? " (dynamic)" : "");
538 /* populate children from any spi device tables */
539 scan_boardinfo(master);
544 EXPORT_SYMBOL_GPL(spi_register_master);
547 static int __unregister(struct device *dev, void *master_dev)
549 /* note: before about 2.6.14-rc1 this would corrupt memory: */
550 if (dev != master_dev)
551 spi_unregister_device(to_spi_device(dev));
556 * spi_unregister_master - unregister SPI master controller
557 * @master: the master being unregistered
560 * This call is used only by SPI master controller drivers, which are the
561 * only ones directly touching chip registers.
563 * This must be called from context that can sleep.
565 void spi_unregister_master(struct spi_master *master)
569 dummy = device_for_each_child(master->dev.parent, &master->dev,
571 device_unregister(&master->dev);
573 EXPORT_SYMBOL_GPL(spi_unregister_master);
575 static int __spi_master_match(struct device *dev, void *data)
577 struct spi_master *m;
580 m = container_of(dev, struct spi_master, dev);
581 return m->bus_num == *bus_num;
585 * spi_busnum_to_master - look up master associated with bus_num
586 * @bus_num: the master's bus number
589 * This call may be used with devices that are registered after
590 * arch init time. It returns a refcounted pointer to the relevant
591 * spi_master (which the caller must release), or NULL if there is
592 * no such master registered.
594 struct spi_master *spi_busnum_to_master(u16 bus_num)
597 struct spi_master *master = NULL;
599 dev = class_find_device(&spi_master_class, NULL, &bus_num,
602 master = container_of(dev, struct spi_master, dev);
603 /* reference got in class_find_device */
606 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
609 /*-------------------------------------------------------------------------*/
611 /* Core methods for SPI master protocol drivers. Some of the
612 * other core methods are currently defined as inline functions.
616 * spi_setup - setup SPI mode and clock rate
617 * @spi: the device whose settings are being modified
618 * Context: can sleep, and no requests are queued to the device
620 * SPI protocol drivers may need to update the transfer mode if the
621 * device doesn't work with its default. They may likewise need
622 * to update clock rates or word sizes from initial values. This function
623 * changes those settings, and must be called from a context that can sleep.
624 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
625 * effect the next time the device is selected and data is transferred to
626 * or from it. When this function returns, the spi device is deselected.
628 * Note that this call will fail if the protocol driver specifies an option
629 * that the underlying controller or its driver does not support. For
630 * example, not all hardware supports wire transfers using nine bit words,
631 * LSB-first wire encoding, or active-high chipselects.
633 int spi_setup(struct spi_device *spi)
638 /* help drivers fail *cleanly* when they need options
639 * that aren't supported with their current master
641 bad_bits = spi->mode & ~spi->master->mode_bits;
643 dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
648 if (!spi->bits_per_word)
649 spi->bits_per_word = 8;
651 status = spi->master->setup(spi);
653 dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
654 "%u bits/w, %u Hz max --> %d\n",
655 (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
656 (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
657 (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
658 (spi->mode & SPI_3WIRE) ? "3wire, " : "",
659 (spi->mode & SPI_LOOP) ? "loopback, " : "",
660 spi->bits_per_word, spi->max_speed_hz,
665 EXPORT_SYMBOL_GPL(spi_setup);
668 * spi_async - asynchronous SPI transfer
669 * @spi: device with which data will be exchanged
670 * @message: describes the data transfers, including completion callback
671 * Context: any (irqs may be blocked, etc)
673 * This call may be used in_irq and other contexts which can't sleep,
674 * as well as from task contexts which can sleep.
676 * The completion callback is invoked in a context which can't sleep.
677 * Before that invocation, the value of message->status is undefined.
678 * When the callback is issued, message->status holds either zero (to
679 * indicate complete success) or a negative error code. After that
680 * callback returns, the driver which issued the transfer request may
681 * deallocate the associated memory; it's no longer in use by any SPI
682 * core or controller driver code.
684 * Note that although all messages to a spi_device are handled in
685 * FIFO order, messages may go to different devices in other orders.
686 * Some device might be higher priority, or have various "hard" access
687 * time requirements, for example.
689 * On detection of any fault during the transfer, processing of
690 * the entire message is aborted, and the device is deselected.
691 * Until returning from the associated message completion callback,
692 * no other spi_message queued to that device will be processed.
693 * (This rule applies equally to all the synchronous transfer calls,
694 * which are wrappers around this core asynchronous primitive.)
696 int spi_async(struct spi_device *spi, struct spi_message *message)
698 struct spi_master *master = spi->master;
700 /* Half-duplex links include original MicroWire, and ones with
701 * only one data pin like SPI_3WIRE (switches direction) or where
702 * either MOSI or MISO is missing. They can also be caused by
703 * software limitations.
705 if ((master->flags & SPI_MASTER_HALF_DUPLEX)
706 || (spi->mode & SPI_3WIRE)) {
707 struct spi_transfer *xfer;
708 unsigned flags = master->flags;
710 list_for_each_entry(xfer, &message->transfers, transfer_list) {
711 if (xfer->rx_buf && xfer->tx_buf)
713 if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
715 if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
721 message->status = -EINPROGRESS;
722 return master->transfer(spi, message);
724 EXPORT_SYMBOL_GPL(spi_async);
727 /*-------------------------------------------------------------------------*/
729 /* Utility methods for SPI master protocol drivers, layered on
730 * top of the core. Some other utility methods are defined as
734 static void spi_complete(void *arg)
740 * spi_sync - blocking/synchronous SPI data transfers
741 * @spi: device with which data will be exchanged
742 * @message: describes the data transfers
745 * This call may only be used from a context that may sleep. The sleep
746 * is non-interruptible, and has no timeout. Low-overhead controller
747 * drivers may DMA directly into and out of the message buffers.
749 * Note that the SPI device's chip select is active during the message,
750 * and then is normally disabled between messages. Drivers for some
751 * frequently-used devices may want to minimize costs of selecting a chip,
752 * by leaving it selected in anticipation that the next message will go
753 * to the same chip. (That may increase power usage.)
755 * Also, the caller is guaranteeing that the memory associated with the
756 * message will not be freed before this call returns.
758 * It returns zero on success, else a negative error code.
760 int spi_sync(struct spi_device *spi, struct spi_message *message)
762 DECLARE_COMPLETION_ONSTACK(done);
765 message->complete = spi_complete;
766 message->context = &done;
767 status = spi_async(spi, message);
769 wait_for_completion(&done);
770 status = message->status;
772 message->context = NULL;
775 EXPORT_SYMBOL_GPL(spi_sync);
777 /* portable code must never pass more than 32 bytes */
778 #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
783 * spi_write_then_read - SPI synchronous write followed by read
784 * @spi: device with which data will be exchanged
785 * @txbuf: data to be written (need not be dma-safe)
786 * @n_tx: size of txbuf, in bytes
787 * @rxbuf: buffer into which data will be read (need not be dma-safe)
788 * @n_rx: size of rxbuf, in bytes
791 * This performs a half duplex MicroWire style transaction with the
792 * device, sending txbuf and then reading rxbuf. The return value
793 * is zero for success, else a negative errno status code.
794 * This call may only be used from a context that may sleep.
796 * Parameters to this routine are always copied using a small buffer;
797 * portable code should never use this for more than 32 bytes.
798 * Performance-sensitive or bulk transfer code should instead use
799 * spi_{async,sync}() calls with dma-safe buffers.
801 int spi_write_then_read(struct spi_device *spi,
802 const u8 *txbuf, unsigned n_tx,
803 u8 *rxbuf, unsigned n_rx)
805 static DEFINE_MUTEX(lock);
808 struct spi_message message;
809 struct spi_transfer x[2];
812 /* Use preallocated DMA-safe buffer. We can't avoid copying here,
813 * (as a pure convenience thing), but we can keep heap costs
814 * out of the hot path ...
816 if ((n_tx + n_rx) > SPI_BUFSIZ)
819 spi_message_init(&message);
820 memset(x, 0, sizeof x);
823 spi_message_add_tail(&x[0], &message);
827 spi_message_add_tail(&x[1], &message);
830 /* ... unless someone else is using the pre-allocated buffer */
831 if (!mutex_trylock(&lock)) {
832 local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
838 memcpy(local_buf, txbuf, n_tx);
839 x[0].tx_buf = local_buf;
840 x[1].rx_buf = local_buf + n_tx;
843 status = spi_sync(spi, &message);
845 memcpy(rxbuf, x[1].rx_buf, n_rx);
847 if (x[0].tx_buf == buf)
854 EXPORT_SYMBOL_GPL(spi_write_then_read);
856 /*-------------------------------------------------------------------------*/
858 static int __init spi_init(void)
862 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
868 status = bus_register(&spi_bus_type);
872 status = class_register(&spi_master_class);
878 bus_unregister(&spi_bus_type);
886 /* board_info is normally registered in arch_initcall(),
887 * but even essential drivers wait till later
889 * REVISIT only boardinfo really needs static linking. the rest (device and
890 * driver registration) _could_ be dynamically linked (modular) ... costs
891 * include needing to have boardinfo data structures be much more public.
893 postcore_initcall(spi_init);