Commit | Line | Data |
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8ae12a0d DB |
1 | /* |
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 | ||
8ae12a0d DB |
21 | #include <linux/kernel.h> |
22 | #include <linux/device.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/cache.h> | |
94040828 | 25 | #include <linux/mutex.h> |
8ae12a0d DB |
26 | #include <linux/spi/spi.h> |
27 | ||
28 | ||
b885244e DB |
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". | |
8ae12a0d DB |
32 | */ |
33 | static void spidev_release(struct device *dev) | |
34 | { | |
0ffa0285 | 35 | struct spi_device *spi = to_spi_device(dev); |
8ae12a0d DB |
36 | |
37 | /* spi masters may cleanup for released devices */ | |
38 | if (spi->master->cleanup) | |
39 | spi->master->cleanup(spi); | |
40 | ||
0c868461 | 41 | spi_master_put(spi->master); |
8ae12a0d DB |
42 | kfree(dev); |
43 | } | |
44 | ||
45 | static ssize_t | |
46 | modalias_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 | ||
53 | static 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 | ||
62 | static 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 | ||
7eff2e7a | 69 | static int spi_uevent(struct device *dev, struct kobj_uevent_env *env) |
8ae12a0d DB |
70 | { |
71 | const struct spi_device *spi = to_spi_device(dev); | |
72 | ||
7eff2e7a | 73 | add_uevent_var(env, "MODALIAS=%s", spi->modalias); |
8ae12a0d DB |
74 | return 0; |
75 | } | |
76 | ||
77 | #ifdef CONFIG_PM | |
78 | ||
8ae12a0d DB |
79 | static int spi_suspend(struct device *dev, pm_message_t message) |
80 | { | |
3c72426f | 81 | int value = 0; |
b885244e | 82 | struct spi_driver *drv = to_spi_driver(dev->driver); |
8ae12a0d | 83 | |
8ae12a0d | 84 | /* suspend will stop irqs and dma; no more i/o */ |
3c72426f DB |
85 | if (drv) { |
86 | if (drv->suspend) | |
87 | value = drv->suspend(to_spi_device(dev), message); | |
88 | else | |
89 | dev_dbg(dev, "... can't suspend\n"); | |
90 | } | |
8ae12a0d DB |
91 | return value; |
92 | } | |
93 | ||
94 | static int spi_resume(struct device *dev) | |
95 | { | |
3c72426f | 96 | int value = 0; |
b885244e | 97 | struct spi_driver *drv = to_spi_driver(dev->driver); |
8ae12a0d | 98 | |
8ae12a0d | 99 | /* resume may restart the i/o queue */ |
3c72426f DB |
100 | if (drv) { |
101 | if (drv->resume) | |
102 | value = drv->resume(to_spi_device(dev)); | |
103 | else | |
104 | dev_dbg(dev, "... can't resume\n"); | |
105 | } | |
8ae12a0d DB |
106 | return value; |
107 | } | |
108 | ||
109 | #else | |
110 | #define spi_suspend NULL | |
111 | #define spi_resume NULL | |
112 | #endif | |
113 | ||
114 | struct bus_type spi_bus_type = { | |
115 | .name = "spi", | |
116 | .dev_attrs = spi_dev_attrs, | |
117 | .match = spi_match_device, | |
118 | .uevent = spi_uevent, | |
119 | .suspend = spi_suspend, | |
120 | .resume = spi_resume, | |
121 | }; | |
122 | EXPORT_SYMBOL_GPL(spi_bus_type); | |
123 | ||
b885244e DB |
124 | |
125 | static int spi_drv_probe(struct device *dev) | |
126 | { | |
127 | const struct spi_driver *sdrv = to_spi_driver(dev->driver); | |
128 | ||
129 | return sdrv->probe(to_spi_device(dev)); | |
130 | } | |
131 | ||
132 | static int spi_drv_remove(struct device *dev) | |
133 | { | |
134 | const struct spi_driver *sdrv = to_spi_driver(dev->driver); | |
135 | ||
136 | return sdrv->remove(to_spi_device(dev)); | |
137 | } | |
138 | ||
139 | static void spi_drv_shutdown(struct device *dev) | |
140 | { | |
141 | const struct spi_driver *sdrv = to_spi_driver(dev->driver); | |
142 | ||
143 | sdrv->shutdown(to_spi_device(dev)); | |
144 | } | |
145 | ||
33e34dc6 DB |
146 | /** |
147 | * spi_register_driver - register a SPI driver | |
148 | * @sdrv: the driver to register | |
149 | * Context: can sleep | |
150 | */ | |
b885244e DB |
151 | int spi_register_driver(struct spi_driver *sdrv) |
152 | { | |
153 | sdrv->driver.bus = &spi_bus_type; | |
154 | if (sdrv->probe) | |
155 | sdrv->driver.probe = spi_drv_probe; | |
156 | if (sdrv->remove) | |
157 | sdrv->driver.remove = spi_drv_remove; | |
158 | if (sdrv->shutdown) | |
159 | sdrv->driver.shutdown = spi_drv_shutdown; | |
160 | return driver_register(&sdrv->driver); | |
161 | } | |
162 | EXPORT_SYMBOL_GPL(spi_register_driver); | |
163 | ||
8ae12a0d DB |
164 | /*-------------------------------------------------------------------------*/ |
165 | ||
166 | /* SPI devices should normally not be created by SPI device drivers; that | |
167 | * would make them board-specific. Similarly with SPI master drivers. | |
168 | * Device registration normally goes into like arch/.../mach.../board-YYY.c | |
169 | * with other readonly (flashable) information about mainboard devices. | |
170 | */ | |
171 | ||
172 | struct boardinfo { | |
173 | struct list_head list; | |
174 | unsigned n_board_info; | |
175 | struct spi_board_info board_info[0]; | |
176 | }; | |
177 | ||
178 | static LIST_HEAD(board_list); | |
94040828 | 179 | static DEFINE_MUTEX(board_lock); |
8ae12a0d DB |
180 | |
181 | ||
33e34dc6 DB |
182 | /** |
183 | * spi_new_device - instantiate one new SPI device | |
184 | * @master: Controller to which device is connected | |
185 | * @chip: Describes the SPI device | |
186 | * Context: can sleep | |
187 | * | |
188 | * On typical mainboards, this is purely internal; and it's not needed | |
8ae12a0d DB |
189 | * after board init creates the hard-wired devices. Some development |
190 | * platforms may not be able to use spi_register_board_info though, and | |
191 | * this is exported so that for example a USB or parport based adapter | |
192 | * driver could add devices (which it would learn about out-of-band). | |
082c8cb4 DB |
193 | * |
194 | * Returns the new device, or NULL. | |
8ae12a0d | 195 | */ |
e9d5a461 AB |
196 | struct spi_device *spi_new_device(struct spi_master *master, |
197 | struct spi_board_info *chip) | |
8ae12a0d DB |
198 | { |
199 | struct spi_device *proxy; | |
49dce689 | 200 | struct device *dev = master->dev.parent; |
8ae12a0d DB |
201 | int status; |
202 | ||
082c8cb4 DB |
203 | /* NOTE: caller did any chip->bus_num checks necessary. |
204 | * | |
205 | * Also, unless we change the return value convention to use | |
206 | * error-or-pointer (not NULL-or-pointer), troubleshootability | |
207 | * suggests syslogged diagnostics are best here (ugh). | |
208 | */ | |
209 | ||
210 | /* Chipselects are numbered 0..max; validate. */ | |
211 | if (chip->chip_select >= master->num_chipselect) { | |
212 | dev_err(dev, "cs%d > max %d\n", | |
213 | chip->chip_select, | |
214 | master->num_chipselect); | |
215 | return NULL; | |
216 | } | |
8ae12a0d | 217 | |
0c868461 | 218 | if (!spi_master_get(master)) |
8ae12a0d DB |
219 | return NULL; |
220 | ||
221 | proxy = kzalloc(sizeof *proxy, GFP_KERNEL); | |
222 | if (!proxy) { | |
223 | dev_err(dev, "can't alloc dev for cs%d\n", | |
224 | chip->chip_select); | |
225 | goto fail; | |
226 | } | |
227 | proxy->master = master; | |
228 | proxy->chip_select = chip->chip_select; | |
229 | proxy->max_speed_hz = chip->max_speed_hz; | |
980a01c9 | 230 | proxy->mode = chip->mode; |
8ae12a0d DB |
231 | proxy->irq = chip->irq; |
232 | proxy->modalias = chip->modalias; | |
233 | ||
234 | snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id, | |
49dce689 | 235 | "%s.%u", master->dev.bus_id, |
8ae12a0d DB |
236 | chip->chip_select); |
237 | proxy->dev.parent = dev; | |
238 | proxy->dev.bus = &spi_bus_type; | |
239 | proxy->dev.platform_data = (void *) chip->platform_data; | |
240 | proxy->controller_data = chip->controller_data; | |
241 | proxy->controller_state = NULL; | |
242 | proxy->dev.release = spidev_release; | |
243 | ||
082c8cb4 | 244 | /* drivers may modify this initial i/o setup */ |
8ae12a0d DB |
245 | status = master->setup(proxy); |
246 | if (status < 0) { | |
082c8cb4 | 247 | dev_err(dev, "can't %s %s, status %d\n", |
8ae12a0d DB |
248 | "setup", proxy->dev.bus_id, status); |
249 | goto fail; | |
250 | } | |
251 | ||
252 | /* driver core catches callers that misbehave by defining | |
253 | * devices that already exist. | |
254 | */ | |
255 | status = device_register(&proxy->dev); | |
256 | if (status < 0) { | |
082c8cb4 | 257 | dev_err(dev, "can't %s %s, status %d\n", |
8ae12a0d | 258 | "add", proxy->dev.bus_id, status); |
b885244e | 259 | goto fail; |
8ae12a0d DB |
260 | } |
261 | dev_dbg(dev, "registered child %s\n", proxy->dev.bus_id); | |
262 | return proxy; | |
b885244e DB |
263 | |
264 | fail: | |
0c868461 | 265 | spi_master_put(master); |
b885244e DB |
266 | kfree(proxy); |
267 | return NULL; | |
8ae12a0d DB |
268 | } |
269 | EXPORT_SYMBOL_GPL(spi_new_device); | |
270 | ||
33e34dc6 DB |
271 | /** |
272 | * spi_register_board_info - register SPI devices for a given board | |
273 | * @info: array of chip descriptors | |
274 | * @n: how many descriptors are provided | |
275 | * Context: can sleep | |
276 | * | |
8ae12a0d DB |
277 | * Board-specific early init code calls this (probably during arch_initcall) |
278 | * with segments of the SPI device table. Any device nodes are created later, | |
279 | * after the relevant parent SPI controller (bus_num) is defined. We keep | |
280 | * this table of devices forever, so that reloading a controller driver will | |
281 | * not make Linux forget about these hard-wired devices. | |
282 | * | |
283 | * Other code can also call this, e.g. a particular add-on board might provide | |
284 | * SPI devices through its expansion connector, so code initializing that board | |
285 | * would naturally declare its SPI devices. | |
286 | * | |
287 | * The board info passed can safely be __initdata ... but be careful of | |
288 | * any embedded pointers (platform_data, etc), they're copied as-is. | |
289 | */ | |
290 | int __init | |
291 | spi_register_board_info(struct spi_board_info const *info, unsigned n) | |
292 | { | |
293 | struct boardinfo *bi; | |
294 | ||
b885244e | 295 | bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL); |
8ae12a0d DB |
296 | if (!bi) |
297 | return -ENOMEM; | |
298 | bi->n_board_info = n; | |
b885244e | 299 | memcpy(bi->board_info, info, n * sizeof *info); |
8ae12a0d | 300 | |
94040828 | 301 | mutex_lock(&board_lock); |
8ae12a0d | 302 | list_add_tail(&bi->list, &board_list); |
94040828 | 303 | mutex_unlock(&board_lock); |
8ae12a0d DB |
304 | return 0; |
305 | } | |
8ae12a0d DB |
306 | |
307 | /* FIXME someone should add support for a __setup("spi", ...) that | |
308 | * creates board info from kernel command lines | |
309 | */ | |
310 | ||
149a6501 | 311 | static void scan_boardinfo(struct spi_master *master) |
8ae12a0d DB |
312 | { |
313 | struct boardinfo *bi; | |
8ae12a0d | 314 | |
94040828 | 315 | mutex_lock(&board_lock); |
8ae12a0d DB |
316 | list_for_each_entry(bi, &board_list, list) { |
317 | struct spi_board_info *chip = bi->board_info; | |
318 | unsigned n; | |
319 | ||
320 | for (n = bi->n_board_info; n > 0; n--, chip++) { | |
321 | if (chip->bus_num != master->bus_num) | |
322 | continue; | |
082c8cb4 DB |
323 | /* NOTE: this relies on spi_new_device to |
324 | * issue diagnostics when given bogus inputs | |
8ae12a0d | 325 | */ |
8ae12a0d DB |
326 | (void) spi_new_device(master, chip); |
327 | } | |
328 | } | |
94040828 | 329 | mutex_unlock(&board_lock); |
8ae12a0d DB |
330 | } |
331 | ||
332 | /*-------------------------------------------------------------------------*/ | |
333 | ||
49dce689 | 334 | static void spi_master_release(struct device *dev) |
8ae12a0d DB |
335 | { |
336 | struct spi_master *master; | |
337 | ||
49dce689 | 338 | master = container_of(dev, struct spi_master, dev); |
8ae12a0d DB |
339 | kfree(master); |
340 | } | |
341 | ||
342 | static struct class spi_master_class = { | |
343 | .name = "spi_master", | |
344 | .owner = THIS_MODULE, | |
49dce689 | 345 | .dev_release = spi_master_release, |
8ae12a0d DB |
346 | }; |
347 | ||
348 | ||
349 | /** | |
350 | * spi_alloc_master - allocate SPI master controller | |
351 | * @dev: the controller, possibly using the platform_bus | |
33e34dc6 | 352 | * @size: how much zeroed driver-private data to allocate; the pointer to this |
49dce689 | 353 | * memory is in the driver_data field of the returned device, |
0c868461 | 354 | * accessible with spi_master_get_devdata(). |
33e34dc6 | 355 | * Context: can sleep |
8ae12a0d DB |
356 | * |
357 | * This call is used only by SPI master controller drivers, which are the | |
358 | * only ones directly touching chip registers. It's how they allocate | |
ba1a0513 | 359 | * an spi_master structure, prior to calling spi_register_master(). |
8ae12a0d DB |
360 | * |
361 | * This must be called from context that can sleep. It returns the SPI | |
362 | * master structure on success, else NULL. | |
363 | * | |
364 | * The caller is responsible for assigning the bus number and initializing | |
ba1a0513 | 365 | * the master's methods before calling spi_register_master(); and (after errors |
0c868461 | 366 | * adding the device) calling spi_master_put() to prevent a memory leak. |
8ae12a0d | 367 | */ |
e9d5a461 | 368 | struct spi_master *spi_alloc_master(struct device *dev, unsigned size) |
8ae12a0d DB |
369 | { |
370 | struct spi_master *master; | |
371 | ||
0c868461 DB |
372 | if (!dev) |
373 | return NULL; | |
374 | ||
e94b1766 | 375 | master = kzalloc(size + sizeof *master, GFP_KERNEL); |
8ae12a0d DB |
376 | if (!master) |
377 | return NULL; | |
378 | ||
49dce689 TJ |
379 | device_initialize(&master->dev); |
380 | master->dev.class = &spi_master_class; | |
381 | master->dev.parent = get_device(dev); | |
0c868461 | 382 | spi_master_set_devdata(master, &master[1]); |
8ae12a0d DB |
383 | |
384 | return master; | |
385 | } | |
386 | EXPORT_SYMBOL_GPL(spi_alloc_master); | |
387 | ||
388 | /** | |
389 | * spi_register_master - register SPI master controller | |
390 | * @master: initialized master, originally from spi_alloc_master() | |
33e34dc6 | 391 | * Context: can sleep |
8ae12a0d DB |
392 | * |
393 | * SPI master controllers connect to their drivers using some non-SPI bus, | |
394 | * such as the platform bus. The final stage of probe() in that code | |
395 | * includes calling spi_register_master() to hook up to this SPI bus glue. | |
396 | * | |
397 | * SPI controllers use board specific (often SOC specific) bus numbers, | |
398 | * and board-specific addressing for SPI devices combines those numbers | |
399 | * with chip select numbers. Since SPI does not directly support dynamic | |
400 | * device identification, boards need configuration tables telling which | |
401 | * chip is at which address. | |
402 | * | |
403 | * This must be called from context that can sleep. It returns zero on | |
404 | * success, else a negative error code (dropping the master's refcount). | |
0c868461 DB |
405 | * After a successful return, the caller is responsible for calling |
406 | * spi_unregister_master(). | |
8ae12a0d | 407 | */ |
e9d5a461 | 408 | int spi_register_master(struct spi_master *master) |
8ae12a0d | 409 | { |
e44a45ae | 410 | static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1); |
49dce689 | 411 | struct device *dev = master->dev.parent; |
8ae12a0d DB |
412 | int status = -ENODEV; |
413 | int dynamic = 0; | |
414 | ||
0c868461 DB |
415 | if (!dev) |
416 | return -ENODEV; | |
417 | ||
082c8cb4 DB |
418 | /* even if it's just one always-selected device, there must |
419 | * be at least one chipselect | |
420 | */ | |
421 | if (master->num_chipselect == 0) | |
422 | return -EINVAL; | |
423 | ||
8ae12a0d | 424 | /* convention: dynamically assigned bus IDs count down from the max */ |
a020ed75 | 425 | if (master->bus_num < 0) { |
082c8cb4 DB |
426 | /* FIXME switch to an IDR based scheme, something like |
427 | * I2C now uses, so we can't run out of "dynamic" IDs | |
428 | */ | |
8ae12a0d | 429 | master->bus_num = atomic_dec_return(&dyn_bus_id); |
b885244e | 430 | dynamic = 1; |
8ae12a0d DB |
431 | } |
432 | ||
433 | /* register the device, then userspace will see it. | |
434 | * registration fails if the bus ID is in use. | |
435 | */ | |
49dce689 | 436 | snprintf(master->dev.bus_id, sizeof master->dev.bus_id, |
8ae12a0d | 437 | "spi%u", master->bus_num); |
49dce689 | 438 | status = device_add(&master->dev); |
b885244e | 439 | if (status < 0) |
8ae12a0d | 440 | goto done; |
49dce689 | 441 | dev_dbg(dev, "registered master %s%s\n", master->dev.bus_id, |
8ae12a0d DB |
442 | dynamic ? " (dynamic)" : ""); |
443 | ||
444 | /* populate children from any spi device tables */ | |
445 | scan_boardinfo(master); | |
446 | status = 0; | |
447 | done: | |
448 | return status; | |
449 | } | |
450 | EXPORT_SYMBOL_GPL(spi_register_master); | |
451 | ||
452 | ||
350d0076 | 453 | static int __unregister(struct device *dev, void *master_dev) |
8ae12a0d DB |
454 | { |
455 | /* note: before about 2.6.14-rc1 this would corrupt memory: */ | |
350d0076 AN |
456 | if (dev != master_dev) |
457 | spi_unregister_device(to_spi_device(dev)); | |
8ae12a0d DB |
458 | return 0; |
459 | } | |
460 | ||
461 | /** | |
462 | * spi_unregister_master - unregister SPI master controller | |
463 | * @master: the master being unregistered | |
33e34dc6 | 464 | * Context: can sleep |
8ae12a0d DB |
465 | * |
466 | * This call is used only by SPI master controller drivers, which are the | |
467 | * only ones directly touching chip registers. | |
468 | * | |
469 | * This must be called from context that can sleep. | |
470 | */ | |
471 | void spi_unregister_master(struct spi_master *master) | |
472 | { | |
89fc9a1a JG |
473 | int dummy; |
474 | ||
350d0076 AN |
475 | dummy = device_for_each_child(master->dev.parent, &master->dev, |
476 | __unregister); | |
49dce689 | 477 | device_unregister(&master->dev); |
8ae12a0d DB |
478 | } |
479 | EXPORT_SYMBOL_GPL(spi_unregister_master); | |
480 | ||
5ed2c832 DY |
481 | static int __spi_master_match(struct device *dev, void *data) |
482 | { | |
483 | struct spi_master *m; | |
484 | u16 *bus_num = data; | |
485 | ||
486 | m = container_of(dev, struct spi_master, dev); | |
487 | return m->bus_num == *bus_num; | |
488 | } | |
489 | ||
8ae12a0d DB |
490 | /** |
491 | * spi_busnum_to_master - look up master associated with bus_num | |
492 | * @bus_num: the master's bus number | |
33e34dc6 | 493 | * Context: can sleep |
8ae12a0d DB |
494 | * |
495 | * This call may be used with devices that are registered after | |
496 | * arch init time. It returns a refcounted pointer to the relevant | |
497 | * spi_master (which the caller must release), or NULL if there is | |
498 | * no such master registered. | |
499 | */ | |
500 | struct spi_master *spi_busnum_to_master(u16 bus_num) | |
501 | { | |
49dce689 | 502 | struct device *dev; |
1e9a51dc | 503 | struct spi_master *master = NULL; |
5ed2c832 DY |
504 | |
505 | dev = class_find_device(&spi_master_class, &bus_num, | |
506 | __spi_master_match); | |
507 | if (dev) | |
508 | master = container_of(dev, struct spi_master, dev); | |
509 | /* reference got in class_find_device */ | |
1e9a51dc | 510 | return master; |
8ae12a0d DB |
511 | } |
512 | EXPORT_SYMBOL_GPL(spi_busnum_to_master); | |
513 | ||
514 | ||
515 | /*-------------------------------------------------------------------------*/ | |
516 | ||
5d870c8e AM |
517 | static void spi_complete(void *arg) |
518 | { | |
519 | complete(arg); | |
520 | } | |
521 | ||
8ae12a0d DB |
522 | /** |
523 | * spi_sync - blocking/synchronous SPI data transfers | |
524 | * @spi: device with which data will be exchanged | |
525 | * @message: describes the data transfers | |
33e34dc6 | 526 | * Context: can sleep |
8ae12a0d DB |
527 | * |
528 | * This call may only be used from a context that may sleep. The sleep | |
529 | * is non-interruptible, and has no timeout. Low-overhead controller | |
530 | * drivers may DMA directly into and out of the message buffers. | |
531 | * | |
532 | * Note that the SPI device's chip select is active during the message, | |
533 | * and then is normally disabled between messages. Drivers for some | |
534 | * frequently-used devices may want to minimize costs of selecting a chip, | |
535 | * by leaving it selected in anticipation that the next message will go | |
536 | * to the same chip. (That may increase power usage.) | |
537 | * | |
0c868461 DB |
538 | * Also, the caller is guaranteeing that the memory associated with the |
539 | * message will not be freed before this call returns. | |
540 | * | |
9b938b74 | 541 | * It returns zero on success, else a negative error code. |
8ae12a0d DB |
542 | */ |
543 | int spi_sync(struct spi_device *spi, struct spi_message *message) | |
544 | { | |
60be6b9a | 545 | DECLARE_COMPLETION_ONSTACK(done); |
8ae12a0d DB |
546 | int status; |
547 | ||
5d870c8e | 548 | message->complete = spi_complete; |
8ae12a0d DB |
549 | message->context = &done; |
550 | status = spi_async(spi, message); | |
9b938b74 | 551 | if (status == 0) { |
8ae12a0d | 552 | wait_for_completion(&done); |
9b938b74 MP |
553 | status = message->status; |
554 | } | |
8ae12a0d DB |
555 | message->context = NULL; |
556 | return status; | |
557 | } | |
558 | EXPORT_SYMBOL_GPL(spi_sync); | |
559 | ||
a9948b61 DB |
560 | /* portable code must never pass more than 32 bytes */ |
561 | #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES) | |
8ae12a0d DB |
562 | |
563 | static u8 *buf; | |
564 | ||
565 | /** | |
566 | * spi_write_then_read - SPI synchronous write followed by read | |
567 | * @spi: device with which data will be exchanged | |
568 | * @txbuf: data to be written (need not be dma-safe) | |
569 | * @n_tx: size of txbuf, in bytes | |
570 | * @rxbuf: buffer into which data will be read | |
571 | * @n_rx: size of rxbuf, in bytes (need not be dma-safe) | |
33e34dc6 | 572 | * Context: can sleep |
8ae12a0d DB |
573 | * |
574 | * This performs a half duplex MicroWire style transaction with the | |
575 | * device, sending txbuf and then reading rxbuf. The return value | |
576 | * is zero for success, else a negative errno status code. | |
b885244e | 577 | * This call may only be used from a context that may sleep. |
8ae12a0d | 578 | * |
0c868461 | 579 | * Parameters to this routine are always copied using a small buffer; |
33e34dc6 DB |
580 | * portable code should never use this for more than 32 bytes. |
581 | * Performance-sensitive or bulk transfer code should instead use | |
0c868461 | 582 | * spi_{async,sync}() calls with dma-safe buffers. |
8ae12a0d DB |
583 | */ |
584 | int spi_write_then_read(struct spi_device *spi, | |
585 | const u8 *txbuf, unsigned n_tx, | |
586 | u8 *rxbuf, unsigned n_rx) | |
587 | { | |
068f4070 | 588 | static DEFINE_MUTEX(lock); |
8ae12a0d DB |
589 | |
590 | int status; | |
591 | struct spi_message message; | |
592 | struct spi_transfer x[2]; | |
593 | u8 *local_buf; | |
594 | ||
595 | /* Use preallocated DMA-safe buffer. We can't avoid copying here, | |
596 | * (as a pure convenience thing), but we can keep heap costs | |
597 | * out of the hot path ... | |
598 | */ | |
599 | if ((n_tx + n_rx) > SPI_BUFSIZ) | |
600 | return -EINVAL; | |
601 | ||
8275c642 VW |
602 | spi_message_init(&message); |
603 | memset(x, 0, sizeof x); | |
604 | if (n_tx) { | |
605 | x[0].len = n_tx; | |
606 | spi_message_add_tail(&x[0], &message); | |
607 | } | |
608 | if (n_rx) { | |
609 | x[1].len = n_rx; | |
610 | spi_message_add_tail(&x[1], &message); | |
611 | } | |
612 | ||
8ae12a0d | 613 | /* ... unless someone else is using the pre-allocated buffer */ |
068f4070 | 614 | if (!mutex_trylock(&lock)) { |
8ae12a0d DB |
615 | local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); |
616 | if (!local_buf) | |
617 | return -ENOMEM; | |
618 | } else | |
619 | local_buf = buf; | |
620 | ||
8ae12a0d DB |
621 | memcpy(local_buf, txbuf, n_tx); |
622 | x[0].tx_buf = local_buf; | |
8ae12a0d | 623 | x[1].rx_buf = local_buf + n_tx; |
8ae12a0d DB |
624 | |
625 | /* do the i/o */ | |
8ae12a0d | 626 | status = spi_sync(spi, &message); |
9b938b74 | 627 | if (status == 0) |
8ae12a0d | 628 | memcpy(rxbuf, x[1].rx_buf, n_rx); |
8ae12a0d DB |
629 | |
630 | if (x[0].tx_buf == buf) | |
068f4070 | 631 | mutex_unlock(&lock); |
8ae12a0d DB |
632 | else |
633 | kfree(local_buf); | |
634 | ||
635 | return status; | |
636 | } | |
637 | EXPORT_SYMBOL_GPL(spi_write_then_read); | |
638 | ||
639 | /*-------------------------------------------------------------------------*/ | |
640 | ||
641 | static int __init spi_init(void) | |
642 | { | |
b885244e DB |
643 | int status; |
644 | ||
e94b1766 | 645 | buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); |
b885244e DB |
646 | if (!buf) { |
647 | status = -ENOMEM; | |
648 | goto err0; | |
649 | } | |
650 | ||
651 | status = bus_register(&spi_bus_type); | |
652 | if (status < 0) | |
653 | goto err1; | |
8ae12a0d | 654 | |
b885244e DB |
655 | status = class_register(&spi_master_class); |
656 | if (status < 0) | |
657 | goto err2; | |
8ae12a0d | 658 | return 0; |
b885244e DB |
659 | |
660 | err2: | |
661 | bus_unregister(&spi_bus_type); | |
662 | err1: | |
663 | kfree(buf); | |
664 | buf = NULL; | |
665 | err0: | |
666 | return status; | |
8ae12a0d | 667 | } |
b885244e | 668 | |
8ae12a0d DB |
669 | /* board_info is normally registered in arch_initcall(), |
670 | * but even essential drivers wait till later | |
b885244e DB |
671 | * |
672 | * REVISIT only boardinfo really needs static linking. the rest (device and | |
673 | * driver registration) _could_ be dynamically linked (modular) ... costs | |
674 | * include needing to have boardinfo data structures be much more public. | |
8ae12a0d DB |
675 | */ |
676 | subsys_initcall(spi_init); | |
677 |