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/spi/spi.h>
29 /* SPI bustype and spi_master class are registered after board init code
30 * provides the SPI device tables, ensuring that both are present by the
31 * time controller driver registration causes spi_devices to "enumerate".
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 snprintf(buf, BUS_ID_SIZE + 1, "%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 int spi_match_device(struct device *dev, struct device_driver *drv)
64 const struct spi_device *spi = to_spi_device(dev);
66 return strncmp(spi->modalias, drv->name, BUS_ID_SIZE) == 0;
69 static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
71 const struct spi_device *spi = to_spi_device(dev);
73 add_uevent_var(env, "MODALIAS=%s", spi->modalias);
80 * NOTE: the suspend() method for an spi_master controller driver
81 * should verify that all its child devices are marked as suspended;
82 * suspend requests delivered through sysfs power/state files don't
83 * enforce such constraints.
85 static int spi_suspend(struct device *dev, pm_message_t message)
88 struct spi_driver *drv = to_spi_driver(dev->driver);
90 if (!drv || !drv->suspend)
93 /* suspend will stop irqs and dma; no more i/o */
94 value = drv->suspend(to_spi_device(dev), message);
96 dev->power.power_state = message;
100 static int spi_resume(struct device *dev)
103 struct spi_driver *drv = to_spi_driver(dev->driver);
105 if (!drv || !drv->resume)
108 /* resume may restart the i/o queue */
109 value = drv->resume(to_spi_device(dev));
111 dev->power.power_state = PMSG_ON;
116 #define spi_suspend NULL
117 #define spi_resume NULL
120 struct bus_type spi_bus_type = {
122 .dev_attrs = spi_dev_attrs,
123 .match = spi_match_device,
124 .uevent = spi_uevent,
125 .suspend = spi_suspend,
126 .resume = spi_resume,
128 EXPORT_SYMBOL_GPL(spi_bus_type);
131 static int spi_drv_probe(struct device *dev)
133 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
135 return sdrv->probe(to_spi_device(dev));
138 static int spi_drv_remove(struct device *dev)
140 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
142 return sdrv->remove(to_spi_device(dev));
145 static void spi_drv_shutdown(struct device *dev)
147 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
149 sdrv->shutdown(to_spi_device(dev));
153 * spi_register_driver - register a SPI driver
154 * @sdrv: the driver to register
157 int spi_register_driver(struct spi_driver *sdrv)
159 sdrv->driver.bus = &spi_bus_type;
161 sdrv->driver.probe = spi_drv_probe;
163 sdrv->driver.remove = spi_drv_remove;
165 sdrv->driver.shutdown = spi_drv_shutdown;
166 return driver_register(&sdrv->driver);
168 EXPORT_SYMBOL_GPL(spi_register_driver);
170 /*-------------------------------------------------------------------------*/
172 /* SPI devices should normally not be created by SPI device drivers; that
173 * would make them board-specific. Similarly with SPI master drivers.
174 * Device registration normally goes into like arch/.../mach.../board-YYY.c
175 * with other readonly (flashable) information about mainboard devices.
179 struct list_head list;
180 unsigned n_board_info;
181 struct spi_board_info board_info[0];
184 static LIST_HEAD(board_list);
185 static DEFINE_MUTEX(board_lock);
189 * spi_new_device - instantiate one new SPI device
190 * @master: Controller to which device is connected
191 * @chip: Describes the SPI device
194 * On typical mainboards, this is purely internal; and it's not needed
195 * after board init creates the hard-wired devices. Some development
196 * platforms may not be able to use spi_register_board_info though, and
197 * this is exported so that for example a USB or parport based adapter
198 * driver could add devices (which it would learn about out-of-band).
200 * Returns the new device, or NULL.
202 struct spi_device *spi_new_device(struct spi_master *master,
203 struct spi_board_info *chip)
205 struct spi_device *proxy;
206 struct device *dev = master->dev.parent;
209 /* NOTE: caller did any chip->bus_num checks necessary.
211 * Also, unless we change the return value convention to use
212 * error-or-pointer (not NULL-or-pointer), troubleshootability
213 * suggests syslogged diagnostics are best here (ugh).
216 /* Chipselects are numbered 0..max; validate. */
217 if (chip->chip_select >= master->num_chipselect) {
218 dev_err(dev, "cs%d > max %d\n",
220 master->num_chipselect);
224 if (!spi_master_get(master))
227 proxy = kzalloc(sizeof *proxy, GFP_KERNEL);
229 dev_err(dev, "can't alloc dev for cs%d\n",
233 proxy->master = master;
234 proxy->chip_select = chip->chip_select;
235 proxy->max_speed_hz = chip->max_speed_hz;
236 proxy->mode = chip->mode;
237 proxy->irq = chip->irq;
238 proxy->modalias = chip->modalias;
240 snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id,
241 "%s.%u", master->dev.bus_id,
243 proxy->dev.parent = dev;
244 proxy->dev.bus = &spi_bus_type;
245 proxy->dev.platform_data = (void *) chip->platform_data;
246 proxy->controller_data = chip->controller_data;
247 proxy->controller_state = NULL;
248 proxy->dev.release = spidev_release;
250 /* drivers may modify this initial i/o setup */
251 status = master->setup(proxy);
253 dev_err(dev, "can't %s %s, status %d\n",
254 "setup", proxy->dev.bus_id, status);
258 /* driver core catches callers that misbehave by defining
259 * devices that already exist.
261 status = device_register(&proxy->dev);
263 dev_err(dev, "can't %s %s, status %d\n",
264 "add", proxy->dev.bus_id, status);
267 dev_dbg(dev, "registered child %s\n", proxy->dev.bus_id);
271 spi_master_put(master);
275 EXPORT_SYMBOL_GPL(spi_new_device);
278 * spi_register_board_info - register SPI devices for a given board
279 * @info: array of chip descriptors
280 * @n: how many descriptors are provided
283 * Board-specific early init code calls this (probably during arch_initcall)
284 * with segments of the SPI device table. Any device nodes are created later,
285 * after the relevant parent SPI controller (bus_num) is defined. We keep
286 * this table of devices forever, so that reloading a controller driver will
287 * not make Linux forget about these hard-wired devices.
289 * Other code can also call this, e.g. a particular add-on board might provide
290 * SPI devices through its expansion connector, so code initializing that board
291 * would naturally declare its SPI devices.
293 * The board info passed can safely be __initdata ... but be careful of
294 * any embedded pointers (platform_data, etc), they're copied as-is.
297 spi_register_board_info(struct spi_board_info const *info, unsigned n)
299 struct boardinfo *bi;
301 bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL);
304 bi->n_board_info = n;
305 memcpy(bi->board_info, info, n * sizeof *info);
307 mutex_lock(&board_lock);
308 list_add_tail(&bi->list, &board_list);
309 mutex_unlock(&board_lock);
313 /* FIXME someone should add support for a __setup("spi", ...) that
314 * creates board info from kernel command lines
317 static void scan_boardinfo(struct spi_master *master)
319 struct boardinfo *bi;
321 mutex_lock(&board_lock);
322 list_for_each_entry(bi, &board_list, list) {
323 struct spi_board_info *chip = bi->board_info;
326 for (n = bi->n_board_info; n > 0; n--, chip++) {
327 if (chip->bus_num != master->bus_num)
329 /* NOTE: this relies on spi_new_device to
330 * issue diagnostics when given bogus inputs
332 (void) spi_new_device(master, chip);
335 mutex_unlock(&board_lock);
338 /*-------------------------------------------------------------------------*/
340 static void spi_master_release(struct device *dev)
342 struct spi_master *master;
344 master = container_of(dev, struct spi_master, dev);
348 static struct class spi_master_class = {
349 .name = "spi_master",
350 .owner = THIS_MODULE,
351 .dev_release = spi_master_release,
356 * spi_alloc_master - allocate SPI master controller
357 * @dev: the controller, possibly using the platform_bus
358 * @size: how much zeroed driver-private data to allocate; the pointer to this
359 * memory is in the driver_data field of the returned device,
360 * accessible with spi_master_get_devdata().
363 * This call is used only by SPI master controller drivers, which are the
364 * only ones directly touching chip registers. It's how they allocate
365 * an spi_master structure, prior to calling spi_register_master().
367 * This must be called from context that can sleep. It returns the SPI
368 * master structure on success, else NULL.
370 * The caller is responsible for assigning the bus number and initializing
371 * the master's methods before calling spi_register_master(); and (after errors
372 * adding the device) calling spi_master_put() to prevent a memory leak.
374 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
376 struct spi_master *master;
381 master = kzalloc(size + sizeof *master, GFP_KERNEL);
385 device_initialize(&master->dev);
386 master->dev.class = &spi_master_class;
387 master->dev.parent = get_device(dev);
388 spi_master_set_devdata(master, &master[1]);
392 EXPORT_SYMBOL_GPL(spi_alloc_master);
395 * spi_register_master - register SPI master controller
396 * @master: initialized master, originally from spi_alloc_master()
399 * SPI master controllers connect to their drivers using some non-SPI bus,
400 * such as the platform bus. The final stage of probe() in that code
401 * includes calling spi_register_master() to hook up to this SPI bus glue.
403 * SPI controllers use board specific (often SOC specific) bus numbers,
404 * and board-specific addressing for SPI devices combines those numbers
405 * with chip select numbers. Since SPI does not directly support dynamic
406 * device identification, boards need configuration tables telling which
407 * chip is at which address.
409 * This must be called from context that can sleep. It returns zero on
410 * success, else a negative error code (dropping the master's refcount).
411 * After a successful return, the caller is responsible for calling
412 * spi_unregister_master().
414 int spi_register_master(struct spi_master *master)
416 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
417 struct device *dev = master->dev.parent;
418 int status = -ENODEV;
424 /* even if it's just one always-selected device, there must
425 * be at least one chipselect
427 if (master->num_chipselect == 0)
430 /* convention: dynamically assigned bus IDs count down from the max */
431 if (master->bus_num < 0) {
432 /* FIXME switch to an IDR based scheme, something like
433 * I2C now uses, so we can't run out of "dynamic" IDs
435 master->bus_num = atomic_dec_return(&dyn_bus_id);
439 /* register the device, then userspace will see it.
440 * registration fails if the bus ID is in use.
442 snprintf(master->dev.bus_id, sizeof master->dev.bus_id,
443 "spi%u", master->bus_num);
444 status = device_add(&master->dev);
447 dev_dbg(dev, "registered master %s%s\n", master->dev.bus_id,
448 dynamic ? " (dynamic)" : "");
450 /* populate children from any spi device tables */
451 scan_boardinfo(master);
456 EXPORT_SYMBOL_GPL(spi_register_master);
459 static int __unregister(struct device *dev, void *master_dev)
461 /* note: before about 2.6.14-rc1 this would corrupt memory: */
462 if (dev != master_dev)
463 spi_unregister_device(to_spi_device(dev));
468 * spi_unregister_master - unregister SPI master controller
469 * @master: the master being unregistered
472 * This call is used only by SPI master controller drivers, which are the
473 * only ones directly touching chip registers.
475 * This must be called from context that can sleep.
477 void spi_unregister_master(struct spi_master *master)
481 dummy = device_for_each_child(master->dev.parent, &master->dev,
483 device_unregister(&master->dev);
485 EXPORT_SYMBOL_GPL(spi_unregister_master);
487 static int __spi_master_match(struct device *dev, void *data)
489 struct spi_master *m;
492 m = container_of(dev, struct spi_master, dev);
493 return m->bus_num == *bus_num;
497 * spi_busnum_to_master - look up master associated with bus_num
498 * @bus_num: the master's bus number
501 * This call may be used with devices that are registered after
502 * arch init time. It returns a refcounted pointer to the relevant
503 * spi_master (which the caller must release), or NULL if there is
504 * no such master registered.
506 struct spi_master *spi_busnum_to_master(u16 bus_num)
509 struct spi_master *master = NULL;
511 dev = class_find_device(&spi_master_class, &bus_num,
514 master = container_of(dev, struct spi_master, dev);
515 /* reference got in class_find_device */
518 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
521 /*-------------------------------------------------------------------------*/
523 static void spi_complete(void *arg)
529 * spi_sync - blocking/synchronous SPI data transfers
530 * @spi: device with which data will be exchanged
531 * @message: describes the data transfers
534 * This call may only be used from a context that may sleep. The sleep
535 * is non-interruptible, and has no timeout. Low-overhead controller
536 * drivers may DMA directly into and out of the message buffers.
538 * Note that the SPI device's chip select is active during the message,
539 * and then is normally disabled between messages. Drivers for some
540 * frequently-used devices may want to minimize costs of selecting a chip,
541 * by leaving it selected in anticipation that the next message will go
542 * to the same chip. (That may increase power usage.)
544 * Also, the caller is guaranteeing that the memory associated with the
545 * message will not be freed before this call returns.
547 * It returns zero on success, else a negative error code.
549 int spi_sync(struct spi_device *spi, struct spi_message *message)
551 DECLARE_COMPLETION_ONSTACK(done);
554 message->complete = spi_complete;
555 message->context = &done;
556 status = spi_async(spi, message);
558 wait_for_completion(&done);
559 status = message->status;
561 message->context = NULL;
564 EXPORT_SYMBOL_GPL(spi_sync);
566 /* portable code must never pass more than 32 bytes */
567 #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
572 * spi_write_then_read - SPI synchronous write followed by read
573 * @spi: device with which data will be exchanged
574 * @txbuf: data to be written (need not be dma-safe)
575 * @n_tx: size of txbuf, in bytes
576 * @rxbuf: buffer into which data will be read
577 * @n_rx: size of rxbuf, in bytes (need not be dma-safe)
580 * This performs a half duplex MicroWire style transaction with the
581 * device, sending txbuf and then reading rxbuf. The return value
582 * is zero for success, else a negative errno status code.
583 * This call may only be used from a context that may sleep.
585 * Parameters to this routine are always copied using a small buffer;
586 * portable code should never use this for more than 32 bytes.
587 * Performance-sensitive or bulk transfer code should instead use
588 * spi_{async,sync}() calls with dma-safe buffers.
590 int spi_write_then_read(struct spi_device *spi,
591 const u8 *txbuf, unsigned n_tx,
592 u8 *rxbuf, unsigned n_rx)
594 static DEFINE_MUTEX(lock);
597 struct spi_message message;
598 struct spi_transfer x[2];
601 /* Use preallocated DMA-safe buffer. We can't avoid copying here,
602 * (as a pure convenience thing), but we can keep heap costs
603 * out of the hot path ...
605 if ((n_tx + n_rx) > SPI_BUFSIZ)
608 spi_message_init(&message);
609 memset(x, 0, sizeof x);
612 spi_message_add_tail(&x[0], &message);
616 spi_message_add_tail(&x[1], &message);
619 /* ... unless someone else is using the pre-allocated buffer */
620 if (!mutex_trylock(&lock)) {
621 local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
627 memcpy(local_buf, txbuf, n_tx);
628 x[0].tx_buf = local_buf;
629 x[1].rx_buf = local_buf + n_tx;
632 status = spi_sync(spi, &message);
634 memcpy(rxbuf, x[1].rx_buf, n_rx);
636 if (x[0].tx_buf == buf)
643 EXPORT_SYMBOL_GPL(spi_write_then_read);
645 /*-------------------------------------------------------------------------*/
647 static int __init spi_init(void)
651 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
657 status = bus_register(&spi_bus_type);
661 status = class_register(&spi_master_class);
667 bus_unregister(&spi_bus_type);
675 /* board_info is normally registered in arch_initcall(),
676 * but even essential drivers wait till later
678 * REVISIT only boardinfo really needs static linking. the rest (device and
679 * driver registration) _could_ be dynamically linked (modular) ... costs
680 * include needing to have boardinfo data structures be much more public.
682 subsys_initcall(spi_init);