blob: 1cea4a6799fe66c3e6fd94eaf56b3ed52b13e2cb [file] [log] [blame]
David Brownell8ae12a02006-01-08 13:34:19 -08001/*
2 * spi.c - SPI init/core code
3 *
4 * Copyright (C) 2005 David Brownell
5 *
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.
10 *
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.
15 *
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.
19 */
20
21#include <linux/autoconf.h>
22#include <linux/kernel.h>
23#include <linux/device.h>
24#include <linux/init.h>
25#include <linux/cache.h>
26#include <linux/spi/spi.h>
27
28
David Brownellb8852442006-01-08 13:34:23 -080029/* 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".
David Brownell8ae12a02006-01-08 13:34:19 -080032 */
33static void spidev_release(struct device *dev)
34{
35 const struct spi_device *spi = to_spi_device(dev);
36
37 /* spi masters may cleanup for released devices */
38 if (spi->master->cleanup)
39 spi->master->cleanup(spi);
40
David Brownell0c868462006-01-08 13:34:25 -080041 spi_master_put(spi->master);
David Brownell8ae12a02006-01-08 13:34:19 -080042 kfree(dev);
43}
44
45static ssize_t
46modalias_show(struct device *dev, struct device_attribute *a, char *buf)
47{
48 const struct spi_device *spi = to_spi_device(dev);
49
50 return snprintf(buf, BUS_ID_SIZE + 1, "%s\n", spi->modalias);
51}
52
53static struct device_attribute spi_dev_attrs[] = {
54 __ATTR_RO(modalias),
55 __ATTR_NULL,
56};
57
58/* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
59 * and the sysfs version makes coldplug work too.
60 */
61
62static int spi_match_device(struct device *dev, struct device_driver *drv)
63{
64 const struct spi_device *spi = to_spi_device(dev);
65
66 return strncmp(spi->modalias, drv->name, BUS_ID_SIZE) == 0;
67}
68
69static int spi_uevent(struct device *dev, char **envp, int num_envp,
70 char *buffer, int buffer_size)
71{
72 const struct spi_device *spi = to_spi_device(dev);
73
74 envp[0] = buffer;
75 snprintf(buffer, buffer_size, "MODALIAS=%s", spi->modalias);
76 envp[1] = NULL;
77 return 0;
78}
79
80#ifdef CONFIG_PM
81
David Brownellb8852442006-01-08 13:34:23 -080082/*
David Brownell8ae12a02006-01-08 13:34:19 -080083 * NOTE: the suspend() method for an spi_master controller driver
84 * should verify that all its child devices are marked as suspended;
85 * suspend requests delivered through sysfs power/state files don't
86 * enforce such constraints.
87 */
88static int spi_suspend(struct device *dev, pm_message_t message)
89{
David Brownellb8852442006-01-08 13:34:23 -080090 int value;
91 struct spi_driver *drv = to_spi_driver(dev->driver);
David Brownell8ae12a02006-01-08 13:34:19 -080092
Stephen Streetd2799f02006-02-20 18:27:56 -080093 if (!drv || !drv->suspend)
David Brownell8ae12a02006-01-08 13:34:19 -080094 return 0;
95
96 /* suspend will stop irqs and dma; no more i/o */
David Brownellb8852442006-01-08 13:34:23 -080097 value = drv->suspend(to_spi_device(dev), message);
David Brownell8ae12a02006-01-08 13:34:19 -080098 if (value == 0)
99 dev->power.power_state = message;
100 return value;
101}
102
103static int spi_resume(struct device *dev)
104{
David Brownellb8852442006-01-08 13:34:23 -0800105 int value;
106 struct spi_driver *drv = to_spi_driver(dev->driver);
David Brownell8ae12a02006-01-08 13:34:19 -0800107
Stephen Streetd2799f02006-02-20 18:27:56 -0800108 if (!drv || !drv->resume)
David Brownell8ae12a02006-01-08 13:34:19 -0800109 return 0;
110
111 /* resume may restart the i/o queue */
David Brownellb8852442006-01-08 13:34:23 -0800112 value = drv->resume(to_spi_device(dev));
David Brownell8ae12a02006-01-08 13:34:19 -0800113 if (value == 0)
114 dev->power.power_state = PMSG_ON;
115 return value;
116}
117
118#else
119#define spi_suspend NULL
120#define spi_resume NULL
121#endif
122
123struct bus_type spi_bus_type = {
124 .name = "spi",
125 .dev_attrs = spi_dev_attrs,
126 .match = spi_match_device,
127 .uevent = spi_uevent,
128 .suspend = spi_suspend,
129 .resume = spi_resume,
130};
131EXPORT_SYMBOL_GPL(spi_bus_type);
132
David Brownellb8852442006-01-08 13:34:23 -0800133
134static int spi_drv_probe(struct device *dev)
135{
136 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
137
138 return sdrv->probe(to_spi_device(dev));
139}
140
141static int spi_drv_remove(struct device *dev)
142{
143 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
144
145 return sdrv->remove(to_spi_device(dev));
146}
147
148static void spi_drv_shutdown(struct device *dev)
149{
150 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
151
152 sdrv->shutdown(to_spi_device(dev));
153}
154
155int spi_register_driver(struct spi_driver *sdrv)
156{
157 sdrv->driver.bus = &spi_bus_type;
158 if (sdrv->probe)
159 sdrv->driver.probe = spi_drv_probe;
160 if (sdrv->remove)
161 sdrv->driver.remove = spi_drv_remove;
162 if (sdrv->shutdown)
163 sdrv->driver.shutdown = spi_drv_shutdown;
164 return driver_register(&sdrv->driver);
165}
166EXPORT_SYMBOL_GPL(spi_register_driver);
167
David Brownell8ae12a02006-01-08 13:34:19 -0800168/*-------------------------------------------------------------------------*/
169
170/* SPI devices should normally not be created by SPI device drivers; that
171 * would make them board-specific. Similarly with SPI master drivers.
172 * Device registration normally goes into like arch/.../mach.../board-YYY.c
173 * with other readonly (flashable) information about mainboard devices.
174 */
175
176struct boardinfo {
177 struct list_head list;
178 unsigned n_board_info;
179 struct spi_board_info board_info[0];
180};
181
182static LIST_HEAD(board_list);
183static DECLARE_MUTEX(board_lock);
184
185
186/* On typical mainboards, this is purely internal; and it's not needed
187 * after board init creates the hard-wired devices. Some development
188 * platforms may not be able to use spi_register_board_info though, and
189 * this is exported so that for example a USB or parport based adapter
190 * driver could add devices (which it would learn about out-of-band).
191 */
192struct spi_device *__init_or_module
193spi_new_device(struct spi_master *master, struct spi_board_info *chip)
194{
195 struct spi_device *proxy;
196 struct device *dev = master->cdev.dev;
197 int status;
198
199 /* NOTE: caller did any chip->bus_num checks necessary */
200
David Brownell0c868462006-01-08 13:34:25 -0800201 if (!spi_master_get(master))
David Brownell8ae12a02006-01-08 13:34:19 -0800202 return NULL;
203
204 proxy = kzalloc(sizeof *proxy, GFP_KERNEL);
205 if (!proxy) {
206 dev_err(dev, "can't alloc dev for cs%d\n",
207 chip->chip_select);
208 goto fail;
209 }
210 proxy->master = master;
211 proxy->chip_select = chip->chip_select;
212 proxy->max_speed_hz = chip->max_speed_hz;
213 proxy->irq = chip->irq;
214 proxy->modalias = chip->modalias;
215
216 snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id,
217 "%s.%u", master->cdev.class_id,
218 chip->chip_select);
219 proxy->dev.parent = dev;
220 proxy->dev.bus = &spi_bus_type;
221 proxy->dev.platform_data = (void *) chip->platform_data;
222 proxy->controller_data = chip->controller_data;
223 proxy->controller_state = NULL;
224 proxy->dev.release = spidev_release;
225
226 /* drivers may modify this default i/o setup */
227 status = master->setup(proxy);
228 if (status < 0) {
229 dev_dbg(dev, "can't %s %s, status %d\n",
230 "setup", proxy->dev.bus_id, status);
231 goto fail;
232 }
233
234 /* driver core catches callers that misbehave by defining
235 * devices that already exist.
236 */
237 status = device_register(&proxy->dev);
238 if (status < 0) {
239 dev_dbg(dev, "can't %s %s, status %d\n",
240 "add", proxy->dev.bus_id, status);
David Brownellb8852442006-01-08 13:34:23 -0800241 goto fail;
David Brownell8ae12a02006-01-08 13:34:19 -0800242 }
243 dev_dbg(dev, "registered child %s\n", proxy->dev.bus_id);
244 return proxy;
David Brownellb8852442006-01-08 13:34:23 -0800245
246fail:
David Brownell0c868462006-01-08 13:34:25 -0800247 spi_master_put(master);
David Brownellb8852442006-01-08 13:34:23 -0800248 kfree(proxy);
249 return NULL;
David Brownell8ae12a02006-01-08 13:34:19 -0800250}
251EXPORT_SYMBOL_GPL(spi_new_device);
252
253/*
254 * Board-specific early init code calls this (probably during arch_initcall)
255 * with segments of the SPI device table. Any device nodes are created later,
256 * after the relevant parent SPI controller (bus_num) is defined. We keep
257 * this table of devices forever, so that reloading a controller driver will
258 * not make Linux forget about these hard-wired devices.
259 *
260 * Other code can also call this, e.g. a particular add-on board might provide
261 * SPI devices through its expansion connector, so code initializing that board
262 * would naturally declare its SPI devices.
263 *
264 * The board info passed can safely be __initdata ... but be careful of
265 * any embedded pointers (platform_data, etc), they're copied as-is.
266 */
267int __init
268spi_register_board_info(struct spi_board_info const *info, unsigned n)
269{
270 struct boardinfo *bi;
271
David Brownellb8852442006-01-08 13:34:23 -0800272 bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL);
David Brownell8ae12a02006-01-08 13:34:19 -0800273 if (!bi)
274 return -ENOMEM;
275 bi->n_board_info = n;
David Brownellb8852442006-01-08 13:34:23 -0800276 memcpy(bi->board_info, info, n * sizeof *info);
David Brownell8ae12a02006-01-08 13:34:19 -0800277
278 down(&board_lock);
279 list_add_tail(&bi->list, &board_list);
280 up(&board_lock);
281 return 0;
282}
283EXPORT_SYMBOL_GPL(spi_register_board_info);
284
285/* FIXME someone should add support for a __setup("spi", ...) that
286 * creates board info from kernel command lines
287 */
288
289static void __init_or_module
290scan_boardinfo(struct spi_master *master)
291{
292 struct boardinfo *bi;
293 struct device *dev = master->cdev.dev;
294
295 down(&board_lock);
296 list_for_each_entry(bi, &board_list, list) {
297 struct spi_board_info *chip = bi->board_info;
298 unsigned n;
299
300 for (n = bi->n_board_info; n > 0; n--, chip++) {
301 if (chip->bus_num != master->bus_num)
302 continue;
303 /* some controllers only have one chip, so they
304 * might not use chipselects. otherwise, the
305 * chipselects are numbered 0..max.
306 */
307 if (chip->chip_select >= master->num_chipselect
308 && master->num_chipselect) {
309 dev_dbg(dev, "cs%d > max %d\n",
310 chip->chip_select,
311 master->num_chipselect);
312 continue;
313 }
314 (void) spi_new_device(master, chip);
315 }
316 }
317 up(&board_lock);
318}
319
320/*-------------------------------------------------------------------------*/
321
322static void spi_master_release(struct class_device *cdev)
323{
324 struct spi_master *master;
325
326 master = container_of(cdev, struct spi_master, cdev);
David Brownell8ae12a02006-01-08 13:34:19 -0800327 kfree(master);
328}
329
330static struct class spi_master_class = {
331 .name = "spi_master",
332 .owner = THIS_MODULE,
333 .release = spi_master_release,
334};
335
336
337/**
338 * spi_alloc_master - allocate SPI master controller
339 * @dev: the controller, possibly using the platform_bus
David Brownell0c868462006-01-08 13:34:25 -0800340 * @size: how much driver-private data to preallocate; the pointer to this
dmitry pervushinba1a0512006-05-20 15:00:14 -0700341 * memory is in the class_data field of the returned class_device,
David Brownell0c868462006-01-08 13:34:25 -0800342 * accessible with spi_master_get_devdata().
David Brownell8ae12a02006-01-08 13:34:19 -0800343 *
344 * This call is used only by SPI master controller drivers, which are the
345 * only ones directly touching chip registers. It's how they allocate
dmitry pervushinba1a0512006-05-20 15:00:14 -0700346 * an spi_master structure, prior to calling spi_register_master().
David Brownell8ae12a02006-01-08 13:34:19 -0800347 *
348 * This must be called from context that can sleep. It returns the SPI
349 * master structure on success, else NULL.
350 *
351 * The caller is responsible for assigning the bus number and initializing
dmitry pervushinba1a0512006-05-20 15:00:14 -0700352 * the master's methods before calling spi_register_master(); and (after errors
David Brownell0c868462006-01-08 13:34:25 -0800353 * adding the device) calling spi_master_put() to prevent a memory leak.
David Brownell8ae12a02006-01-08 13:34:19 -0800354 */
355struct spi_master * __init_or_module
356spi_alloc_master(struct device *dev, unsigned size)
357{
358 struct spi_master *master;
359
David Brownell0c868462006-01-08 13:34:25 -0800360 if (!dev)
361 return NULL;
362
David Brownell8ae12a02006-01-08 13:34:19 -0800363 master = kzalloc(size + sizeof *master, SLAB_KERNEL);
364 if (!master)
365 return NULL;
366
David Brownellb8852442006-01-08 13:34:23 -0800367 class_device_initialize(&master->cdev);
David Brownell8ae12a02006-01-08 13:34:19 -0800368 master->cdev.class = &spi_master_class;
369 master->cdev.dev = get_device(dev);
David Brownell0c868462006-01-08 13:34:25 -0800370 spi_master_set_devdata(master, &master[1]);
David Brownell8ae12a02006-01-08 13:34:19 -0800371
372 return master;
373}
374EXPORT_SYMBOL_GPL(spi_alloc_master);
375
376/**
377 * spi_register_master - register SPI master controller
378 * @master: initialized master, originally from spi_alloc_master()
379 *
380 * SPI master controllers connect to their drivers using some non-SPI bus,
381 * such as the platform bus. The final stage of probe() in that code
382 * includes calling spi_register_master() to hook up to this SPI bus glue.
383 *
384 * SPI controllers use board specific (often SOC specific) bus numbers,
385 * and board-specific addressing for SPI devices combines those numbers
386 * with chip select numbers. Since SPI does not directly support dynamic
387 * device identification, boards need configuration tables telling which
388 * chip is at which address.
389 *
390 * This must be called from context that can sleep. It returns zero on
391 * success, else a negative error code (dropping the master's refcount).
David Brownell0c868462006-01-08 13:34:25 -0800392 * After a successful return, the caller is responsible for calling
393 * spi_unregister_master().
David Brownell8ae12a02006-01-08 13:34:19 -0800394 */
395int __init_or_module
396spi_register_master(struct spi_master *master)
397{
David Brownella020ed72006-04-03 15:49:04 -0700398 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<16) - 1);
David Brownell8ae12a02006-01-08 13:34:19 -0800399 struct device *dev = master->cdev.dev;
400 int status = -ENODEV;
401 int dynamic = 0;
402
David Brownell0c868462006-01-08 13:34:25 -0800403 if (!dev)
404 return -ENODEV;
405
David Brownell8ae12a02006-01-08 13:34:19 -0800406 /* convention: dynamically assigned bus IDs count down from the max */
David Brownella020ed72006-04-03 15:49:04 -0700407 if (master->bus_num < 0) {
David Brownell8ae12a02006-01-08 13:34:19 -0800408 master->bus_num = atomic_dec_return(&dyn_bus_id);
David Brownellb8852442006-01-08 13:34:23 -0800409 dynamic = 1;
David Brownell8ae12a02006-01-08 13:34:19 -0800410 }
411
412 /* register the device, then userspace will see it.
413 * registration fails if the bus ID is in use.
414 */
415 snprintf(master->cdev.class_id, sizeof master->cdev.class_id,
416 "spi%u", master->bus_num);
David Brownellb8852442006-01-08 13:34:23 -0800417 status = class_device_add(&master->cdev);
418 if (status < 0)
David Brownell8ae12a02006-01-08 13:34:19 -0800419 goto done;
David Brownell8ae12a02006-01-08 13:34:19 -0800420 dev_dbg(dev, "registered master %s%s\n", master->cdev.class_id,
421 dynamic ? " (dynamic)" : "");
422
423 /* populate children from any spi device tables */
424 scan_boardinfo(master);
425 status = 0;
426done:
427 return status;
428}
429EXPORT_SYMBOL_GPL(spi_register_master);
430
431
432static int __unregister(struct device *dev, void *unused)
433{
434 /* note: before about 2.6.14-rc1 this would corrupt memory: */
David Brownell0c868462006-01-08 13:34:25 -0800435 spi_unregister_device(to_spi_device(dev));
David Brownell8ae12a02006-01-08 13:34:19 -0800436 return 0;
437}
438
439/**
440 * spi_unregister_master - unregister SPI master controller
441 * @master: the master being unregistered
442 *
443 * This call is used only by SPI master controller drivers, which are the
444 * only ones directly touching chip registers.
445 *
446 * This must be called from context that can sleep.
447 */
448void spi_unregister_master(struct spi_master *master)
449{
David Brownell8ae12a02006-01-08 13:34:19 -0800450 (void) device_for_each_child(master->cdev.dev, NULL, __unregister);
David Brownell0c868462006-01-08 13:34:25 -0800451 class_device_unregister(&master->cdev);
David Brownell8ae12a02006-01-08 13:34:19 -0800452}
453EXPORT_SYMBOL_GPL(spi_unregister_master);
454
455/**
456 * spi_busnum_to_master - look up master associated with bus_num
457 * @bus_num: the master's bus number
458 *
459 * This call may be used with devices that are registered after
460 * arch init time. It returns a refcounted pointer to the relevant
461 * spi_master (which the caller must release), or NULL if there is
462 * no such master registered.
463 */
464struct spi_master *spi_busnum_to_master(u16 bus_num)
465{
466 if (bus_num) {
467 char name[8];
468 struct kobject *bus;
469
470 snprintf(name, sizeof name, "spi%u", bus_num);
471 bus = kset_find_obj(&spi_master_class.subsys.kset, name);
472 if (bus)
473 return container_of(bus, struct spi_master, cdev.kobj);
474 }
475 return NULL;
476}
477EXPORT_SYMBOL_GPL(spi_busnum_to_master);
478
479
480/*-------------------------------------------------------------------------*/
481
Andrew Morton5d870c82006-01-11 11:23:49 -0800482static void spi_complete(void *arg)
483{
484 complete(arg);
485}
486
David Brownell8ae12a02006-01-08 13:34:19 -0800487/**
488 * spi_sync - blocking/synchronous SPI data transfers
489 * @spi: device with which data will be exchanged
490 * @message: describes the data transfers
491 *
492 * This call may only be used from a context that may sleep. The sleep
493 * is non-interruptible, and has no timeout. Low-overhead controller
494 * drivers may DMA directly into and out of the message buffers.
495 *
496 * Note that the SPI device's chip select is active during the message,
497 * and then is normally disabled between messages. Drivers for some
498 * frequently-used devices may want to minimize costs of selecting a chip,
499 * by leaving it selected in anticipation that the next message will go
500 * to the same chip. (That may increase power usage.)
501 *
David Brownell0c868462006-01-08 13:34:25 -0800502 * Also, the caller is guaranteeing that the memory associated with the
503 * message will not be freed before this call returns.
504 *
David Brownell8ae12a02006-01-08 13:34:19 -0800505 * The return value is a negative error code if the message could not be
506 * submitted, else zero. When the value is zero, then message->status is
507 * also defined: it's the completion code for the transfer, either zero
508 * or a negative error code from the controller driver.
509 */
510int spi_sync(struct spi_device *spi, struct spi_message *message)
511{
512 DECLARE_COMPLETION(done);
513 int status;
514
Andrew Morton5d870c82006-01-11 11:23:49 -0800515 message->complete = spi_complete;
David Brownell8ae12a02006-01-08 13:34:19 -0800516 message->context = &done;
517 status = spi_async(spi, message);
518 if (status == 0)
519 wait_for_completion(&done);
520 message->context = NULL;
521 return status;
522}
523EXPORT_SYMBOL_GPL(spi_sync);
524
David Brownella9948b62006-04-02 10:37:40 -0800525/* portable code must never pass more than 32 bytes */
526#define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
David Brownell8ae12a02006-01-08 13:34:19 -0800527
528static u8 *buf;
529
530/**
531 * spi_write_then_read - SPI synchronous write followed by read
532 * @spi: device with which data will be exchanged
533 * @txbuf: data to be written (need not be dma-safe)
534 * @n_tx: size of txbuf, in bytes
535 * @rxbuf: buffer into which data will be read
536 * @n_rx: size of rxbuf, in bytes (need not be dma-safe)
537 *
538 * This performs a half duplex MicroWire style transaction with the
539 * device, sending txbuf and then reading rxbuf. The return value
540 * is zero for success, else a negative errno status code.
David Brownellb8852442006-01-08 13:34:23 -0800541 * This call may only be used from a context that may sleep.
David Brownell8ae12a02006-01-08 13:34:19 -0800542 *
David Brownell0c868462006-01-08 13:34:25 -0800543 * Parameters to this routine are always copied using a small buffer;
544 * performance-sensitive or bulk transfer code should instead use
545 * spi_{async,sync}() calls with dma-safe buffers.
David Brownell8ae12a02006-01-08 13:34:19 -0800546 */
547int spi_write_then_read(struct spi_device *spi,
548 const u8 *txbuf, unsigned n_tx,
549 u8 *rxbuf, unsigned n_rx)
550{
551 static DECLARE_MUTEX(lock);
552
553 int status;
554 struct spi_message message;
555 struct spi_transfer x[2];
556 u8 *local_buf;
557
558 /* Use preallocated DMA-safe buffer. We can't avoid copying here,
559 * (as a pure convenience thing), but we can keep heap costs
560 * out of the hot path ...
561 */
562 if ((n_tx + n_rx) > SPI_BUFSIZ)
563 return -EINVAL;
564
Vitaly Wool8275c642006-01-08 13:34:28 -0800565 spi_message_init(&message);
566 memset(x, 0, sizeof x);
567 if (n_tx) {
568 x[0].len = n_tx;
569 spi_message_add_tail(&x[0], &message);
570 }
571 if (n_rx) {
572 x[1].len = n_rx;
573 spi_message_add_tail(&x[1], &message);
574 }
575
David Brownell8ae12a02006-01-08 13:34:19 -0800576 /* ... unless someone else is using the pre-allocated buffer */
577 if (down_trylock(&lock)) {
578 local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
579 if (!local_buf)
580 return -ENOMEM;
581 } else
582 local_buf = buf;
583
David Brownell8ae12a02006-01-08 13:34:19 -0800584 memcpy(local_buf, txbuf, n_tx);
585 x[0].tx_buf = local_buf;
David Brownell8ae12a02006-01-08 13:34:19 -0800586 x[1].rx_buf = local_buf + n_tx;
David Brownell8ae12a02006-01-08 13:34:19 -0800587
588 /* do the i/o */
David Brownell8ae12a02006-01-08 13:34:19 -0800589 status = spi_sync(spi, &message);
590 if (status == 0) {
591 memcpy(rxbuf, x[1].rx_buf, n_rx);
592 status = message.status;
593 }
594
595 if (x[0].tx_buf == buf)
596 up(&lock);
597 else
598 kfree(local_buf);
599
600 return status;
601}
602EXPORT_SYMBOL_GPL(spi_write_then_read);
603
604/*-------------------------------------------------------------------------*/
605
606static int __init spi_init(void)
607{
David Brownellb8852442006-01-08 13:34:23 -0800608 int status;
David Brownell8ae12a02006-01-08 13:34:19 -0800609
David Brownellb8852442006-01-08 13:34:23 -0800610 buf = kmalloc(SPI_BUFSIZ, SLAB_KERNEL);
611 if (!buf) {
612 status = -ENOMEM;
613 goto err0;
614 }
615
616 status = bus_register(&spi_bus_type);
617 if (status < 0)
618 goto err1;
619
620 status = class_register(&spi_master_class);
621 if (status < 0)
622 goto err2;
David Brownell8ae12a02006-01-08 13:34:19 -0800623 return 0;
David Brownellb8852442006-01-08 13:34:23 -0800624
625err2:
626 bus_unregister(&spi_bus_type);
627err1:
628 kfree(buf);
629 buf = NULL;
630err0:
631 return status;
David Brownell8ae12a02006-01-08 13:34:19 -0800632}
David Brownellb8852442006-01-08 13:34:23 -0800633
David Brownell8ae12a02006-01-08 13:34:19 -0800634/* board_info is normally registered in arch_initcall(),
635 * but even essential drivers wait till later
David Brownellb8852442006-01-08 13:34:23 -0800636 *
637 * REVISIT only boardinfo really needs static linking. the rest (device and
638 * driver registration) _could_ be dynamically linked (modular) ... costs
639 * include needing to have boardinfo data structures be much more public.
David Brownell8ae12a02006-01-08 13:34:19 -0800640 */
641subsys_initcall(spi_init);
642