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 | ||
102eb975 GL |
221 | WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias)); |
222 | ||
8ae12a0d DB |
223 | proxy = kzalloc(sizeof *proxy, GFP_KERNEL); |
224 | if (!proxy) { | |
225 | dev_err(dev, "can't alloc dev for cs%d\n", | |
226 | chip->chip_select); | |
227 | goto fail; | |
228 | } | |
229 | proxy->master = master; | |
230 | proxy->chip_select = chip->chip_select; | |
231 | proxy->max_speed_hz = chip->max_speed_hz; | |
980a01c9 | 232 | proxy->mode = chip->mode; |
8ae12a0d | 233 | proxy->irq = chip->irq; |
102eb975 | 234 | strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias)); |
8ae12a0d DB |
235 | |
236 | snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id, | |
49dce689 | 237 | "%s.%u", master->dev.bus_id, |
8ae12a0d DB |
238 | chip->chip_select); |
239 | proxy->dev.parent = dev; | |
240 | proxy->dev.bus = &spi_bus_type; | |
241 | proxy->dev.platform_data = (void *) chip->platform_data; | |
242 | proxy->controller_data = chip->controller_data; | |
243 | proxy->controller_state = NULL; | |
244 | proxy->dev.release = spidev_release; | |
245 | ||
082c8cb4 | 246 | /* drivers may modify this initial i/o setup */ |
8ae12a0d DB |
247 | status = master->setup(proxy); |
248 | if (status < 0) { | |
082c8cb4 | 249 | dev_err(dev, "can't %s %s, status %d\n", |
8ae12a0d DB |
250 | "setup", proxy->dev.bus_id, status); |
251 | goto fail; | |
252 | } | |
253 | ||
254 | /* driver core catches callers that misbehave by defining | |
255 | * devices that already exist. | |
256 | */ | |
257 | status = device_register(&proxy->dev); | |
258 | if (status < 0) { | |
082c8cb4 | 259 | dev_err(dev, "can't %s %s, status %d\n", |
8ae12a0d | 260 | "add", proxy->dev.bus_id, status); |
b885244e | 261 | goto fail; |
8ae12a0d DB |
262 | } |
263 | dev_dbg(dev, "registered child %s\n", proxy->dev.bus_id); | |
264 | return proxy; | |
b885244e DB |
265 | |
266 | fail: | |
0c868461 | 267 | spi_master_put(master); |
b885244e DB |
268 | kfree(proxy); |
269 | return NULL; | |
8ae12a0d DB |
270 | } |
271 | EXPORT_SYMBOL_GPL(spi_new_device); | |
272 | ||
33e34dc6 DB |
273 | /** |
274 | * spi_register_board_info - register SPI devices for a given board | |
275 | * @info: array of chip descriptors | |
276 | * @n: how many descriptors are provided | |
277 | * Context: can sleep | |
278 | * | |
8ae12a0d DB |
279 | * Board-specific early init code calls this (probably during arch_initcall) |
280 | * with segments of the SPI device table. Any device nodes are created later, | |
281 | * after the relevant parent SPI controller (bus_num) is defined. We keep | |
282 | * this table of devices forever, so that reloading a controller driver will | |
283 | * not make Linux forget about these hard-wired devices. | |
284 | * | |
285 | * Other code can also call this, e.g. a particular add-on board might provide | |
286 | * SPI devices through its expansion connector, so code initializing that board | |
287 | * would naturally declare its SPI devices. | |
288 | * | |
289 | * The board info passed can safely be __initdata ... but be careful of | |
290 | * any embedded pointers (platform_data, etc), they're copied as-is. | |
291 | */ | |
292 | int __init | |
293 | spi_register_board_info(struct spi_board_info const *info, unsigned n) | |
294 | { | |
295 | struct boardinfo *bi; | |
296 | ||
b885244e | 297 | bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL); |
8ae12a0d DB |
298 | if (!bi) |
299 | return -ENOMEM; | |
300 | bi->n_board_info = n; | |
b885244e | 301 | memcpy(bi->board_info, info, n * sizeof *info); |
8ae12a0d | 302 | |
94040828 | 303 | mutex_lock(&board_lock); |
8ae12a0d | 304 | list_add_tail(&bi->list, &board_list); |
94040828 | 305 | mutex_unlock(&board_lock); |
8ae12a0d DB |
306 | return 0; |
307 | } | |
8ae12a0d DB |
308 | |
309 | /* FIXME someone should add support for a __setup("spi", ...) that | |
310 | * creates board info from kernel command lines | |
311 | */ | |
312 | ||
149a6501 | 313 | static void scan_boardinfo(struct spi_master *master) |
8ae12a0d DB |
314 | { |
315 | struct boardinfo *bi; | |
8ae12a0d | 316 | |
94040828 | 317 | mutex_lock(&board_lock); |
8ae12a0d DB |
318 | list_for_each_entry(bi, &board_list, list) { |
319 | struct spi_board_info *chip = bi->board_info; | |
320 | unsigned n; | |
321 | ||
322 | for (n = bi->n_board_info; n > 0; n--, chip++) { | |
323 | if (chip->bus_num != master->bus_num) | |
324 | continue; | |
082c8cb4 DB |
325 | /* NOTE: this relies on spi_new_device to |
326 | * issue diagnostics when given bogus inputs | |
8ae12a0d | 327 | */ |
8ae12a0d DB |
328 | (void) spi_new_device(master, chip); |
329 | } | |
330 | } | |
94040828 | 331 | mutex_unlock(&board_lock); |
8ae12a0d DB |
332 | } |
333 | ||
334 | /*-------------------------------------------------------------------------*/ | |
335 | ||
49dce689 | 336 | static void spi_master_release(struct device *dev) |
8ae12a0d DB |
337 | { |
338 | struct spi_master *master; | |
339 | ||
49dce689 | 340 | master = container_of(dev, struct spi_master, dev); |
8ae12a0d DB |
341 | kfree(master); |
342 | } | |
343 | ||
344 | static struct class spi_master_class = { | |
345 | .name = "spi_master", | |
346 | .owner = THIS_MODULE, | |
49dce689 | 347 | .dev_release = spi_master_release, |
8ae12a0d DB |
348 | }; |
349 | ||
350 | ||
351 | /** | |
352 | * spi_alloc_master - allocate SPI master controller | |
353 | * @dev: the controller, possibly using the platform_bus | |
33e34dc6 | 354 | * @size: how much zeroed driver-private data to allocate; the pointer to this |
49dce689 | 355 | * memory is in the driver_data field of the returned device, |
0c868461 | 356 | * accessible with spi_master_get_devdata(). |
33e34dc6 | 357 | * Context: can sleep |
8ae12a0d DB |
358 | * |
359 | * This call is used only by SPI master controller drivers, which are the | |
360 | * only ones directly touching chip registers. It's how they allocate | |
ba1a0513 | 361 | * an spi_master structure, prior to calling spi_register_master(). |
8ae12a0d DB |
362 | * |
363 | * This must be called from context that can sleep. It returns the SPI | |
364 | * master structure on success, else NULL. | |
365 | * | |
366 | * The caller is responsible for assigning the bus number and initializing | |
ba1a0513 | 367 | * the master's methods before calling spi_register_master(); and (after errors |
0c868461 | 368 | * adding the device) calling spi_master_put() to prevent a memory leak. |
8ae12a0d | 369 | */ |
e9d5a461 | 370 | struct spi_master *spi_alloc_master(struct device *dev, unsigned size) |
8ae12a0d DB |
371 | { |
372 | struct spi_master *master; | |
373 | ||
0c868461 DB |
374 | if (!dev) |
375 | return NULL; | |
376 | ||
e94b1766 | 377 | master = kzalloc(size + sizeof *master, GFP_KERNEL); |
8ae12a0d DB |
378 | if (!master) |
379 | return NULL; | |
380 | ||
49dce689 TJ |
381 | device_initialize(&master->dev); |
382 | master->dev.class = &spi_master_class; | |
383 | master->dev.parent = get_device(dev); | |
0c868461 | 384 | spi_master_set_devdata(master, &master[1]); |
8ae12a0d DB |
385 | |
386 | return master; | |
387 | } | |
388 | EXPORT_SYMBOL_GPL(spi_alloc_master); | |
389 | ||
390 | /** | |
391 | * spi_register_master - register SPI master controller | |
392 | * @master: initialized master, originally from spi_alloc_master() | |
33e34dc6 | 393 | * Context: can sleep |
8ae12a0d DB |
394 | * |
395 | * SPI master controllers connect to their drivers using some non-SPI bus, | |
396 | * such as the platform bus. The final stage of probe() in that code | |
397 | * includes calling spi_register_master() to hook up to this SPI bus glue. | |
398 | * | |
399 | * SPI controllers use board specific (often SOC specific) bus numbers, | |
400 | * and board-specific addressing for SPI devices combines those numbers | |
401 | * with chip select numbers. Since SPI does not directly support dynamic | |
402 | * device identification, boards need configuration tables telling which | |
403 | * chip is at which address. | |
404 | * | |
405 | * This must be called from context that can sleep. It returns zero on | |
406 | * success, else a negative error code (dropping the master's refcount). | |
0c868461 DB |
407 | * After a successful return, the caller is responsible for calling |
408 | * spi_unregister_master(). | |
8ae12a0d | 409 | */ |
e9d5a461 | 410 | int spi_register_master(struct spi_master *master) |
8ae12a0d | 411 | { |
e44a45ae | 412 | static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1); |
49dce689 | 413 | struct device *dev = master->dev.parent; |
8ae12a0d DB |
414 | int status = -ENODEV; |
415 | int dynamic = 0; | |
416 | ||
0c868461 DB |
417 | if (!dev) |
418 | return -ENODEV; | |
419 | ||
082c8cb4 DB |
420 | /* even if it's just one always-selected device, there must |
421 | * be at least one chipselect | |
422 | */ | |
423 | if (master->num_chipselect == 0) | |
424 | return -EINVAL; | |
425 | ||
8ae12a0d | 426 | /* convention: dynamically assigned bus IDs count down from the max */ |
a020ed75 | 427 | if (master->bus_num < 0) { |
082c8cb4 DB |
428 | /* FIXME switch to an IDR based scheme, something like |
429 | * I2C now uses, so we can't run out of "dynamic" IDs | |
430 | */ | |
8ae12a0d | 431 | master->bus_num = atomic_dec_return(&dyn_bus_id); |
b885244e | 432 | dynamic = 1; |
8ae12a0d DB |
433 | } |
434 | ||
435 | /* register the device, then userspace will see it. | |
436 | * registration fails if the bus ID is in use. | |
437 | */ | |
49dce689 | 438 | snprintf(master->dev.bus_id, sizeof master->dev.bus_id, |
8ae12a0d | 439 | "spi%u", master->bus_num); |
49dce689 | 440 | status = device_add(&master->dev); |
b885244e | 441 | if (status < 0) |
8ae12a0d | 442 | goto done; |
49dce689 | 443 | dev_dbg(dev, "registered master %s%s\n", master->dev.bus_id, |
8ae12a0d DB |
444 | dynamic ? " (dynamic)" : ""); |
445 | ||
446 | /* populate children from any spi device tables */ | |
447 | scan_boardinfo(master); | |
448 | status = 0; | |
449 | done: | |
450 | return status; | |
451 | } | |
452 | EXPORT_SYMBOL_GPL(spi_register_master); | |
453 | ||
454 | ||
350d0076 | 455 | static int __unregister(struct device *dev, void *master_dev) |
8ae12a0d DB |
456 | { |
457 | /* note: before about 2.6.14-rc1 this would corrupt memory: */ | |
350d0076 AN |
458 | if (dev != master_dev) |
459 | spi_unregister_device(to_spi_device(dev)); | |
8ae12a0d DB |
460 | return 0; |
461 | } | |
462 | ||
463 | /** | |
464 | * spi_unregister_master - unregister SPI master controller | |
465 | * @master: the master being unregistered | |
33e34dc6 | 466 | * Context: can sleep |
8ae12a0d DB |
467 | * |
468 | * This call is used only by SPI master controller drivers, which are the | |
469 | * only ones directly touching chip registers. | |
470 | * | |
471 | * This must be called from context that can sleep. | |
472 | */ | |
473 | void spi_unregister_master(struct spi_master *master) | |
474 | { | |
89fc9a1a JG |
475 | int dummy; |
476 | ||
350d0076 AN |
477 | dummy = device_for_each_child(master->dev.parent, &master->dev, |
478 | __unregister); | |
49dce689 | 479 | device_unregister(&master->dev); |
8ae12a0d DB |
480 | } |
481 | EXPORT_SYMBOL_GPL(spi_unregister_master); | |
482 | ||
5ed2c832 DY |
483 | static int __spi_master_match(struct device *dev, void *data) |
484 | { | |
485 | struct spi_master *m; | |
486 | u16 *bus_num = data; | |
487 | ||
488 | m = container_of(dev, struct spi_master, dev); | |
489 | return m->bus_num == *bus_num; | |
490 | } | |
491 | ||
8ae12a0d DB |
492 | /** |
493 | * spi_busnum_to_master - look up master associated with bus_num | |
494 | * @bus_num: the master's bus number | |
33e34dc6 | 495 | * Context: can sleep |
8ae12a0d DB |
496 | * |
497 | * This call may be used with devices that are registered after | |
498 | * arch init time. It returns a refcounted pointer to the relevant | |
499 | * spi_master (which the caller must release), or NULL if there is | |
500 | * no such master registered. | |
501 | */ | |
502 | struct spi_master *spi_busnum_to_master(u16 bus_num) | |
503 | { | |
49dce689 | 504 | struct device *dev; |
1e9a51dc | 505 | struct spi_master *master = NULL; |
5ed2c832 | 506 | |
695794ae | 507 | dev = class_find_device(&spi_master_class, NULL, &bus_num, |
5ed2c832 DY |
508 | __spi_master_match); |
509 | if (dev) | |
510 | master = container_of(dev, struct spi_master, dev); | |
511 | /* reference got in class_find_device */ | |
1e9a51dc | 512 | return master; |
8ae12a0d DB |
513 | } |
514 | EXPORT_SYMBOL_GPL(spi_busnum_to_master); | |
515 | ||
516 | ||
517 | /*-------------------------------------------------------------------------*/ | |
518 | ||
5d870c8e AM |
519 | static void spi_complete(void *arg) |
520 | { | |
521 | complete(arg); | |
522 | } | |
523 | ||
8ae12a0d DB |
524 | /** |
525 | * spi_sync - blocking/synchronous SPI data transfers | |
526 | * @spi: device with which data will be exchanged | |
527 | * @message: describes the data transfers | |
33e34dc6 | 528 | * Context: can sleep |
8ae12a0d DB |
529 | * |
530 | * This call may only be used from a context that may sleep. The sleep | |
531 | * is non-interruptible, and has no timeout. Low-overhead controller | |
532 | * drivers may DMA directly into and out of the message buffers. | |
533 | * | |
534 | * Note that the SPI device's chip select is active during the message, | |
535 | * and then is normally disabled between messages. Drivers for some | |
536 | * frequently-used devices may want to minimize costs of selecting a chip, | |
537 | * by leaving it selected in anticipation that the next message will go | |
538 | * to the same chip. (That may increase power usage.) | |
539 | * | |
0c868461 DB |
540 | * Also, the caller is guaranteeing that the memory associated with the |
541 | * message will not be freed before this call returns. | |
542 | * | |
9b938b74 | 543 | * It returns zero on success, else a negative error code. |
8ae12a0d DB |
544 | */ |
545 | int spi_sync(struct spi_device *spi, struct spi_message *message) | |
546 | { | |
60be6b9a | 547 | DECLARE_COMPLETION_ONSTACK(done); |
8ae12a0d DB |
548 | int status; |
549 | ||
5d870c8e | 550 | message->complete = spi_complete; |
8ae12a0d DB |
551 | message->context = &done; |
552 | status = spi_async(spi, message); | |
9b938b74 | 553 | if (status == 0) { |
8ae12a0d | 554 | wait_for_completion(&done); |
9b938b74 MP |
555 | status = message->status; |
556 | } | |
8ae12a0d DB |
557 | message->context = NULL; |
558 | return status; | |
559 | } | |
560 | EXPORT_SYMBOL_GPL(spi_sync); | |
561 | ||
a9948b61 DB |
562 | /* portable code must never pass more than 32 bytes */ |
563 | #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES) | |
8ae12a0d DB |
564 | |
565 | static u8 *buf; | |
566 | ||
567 | /** | |
568 | * spi_write_then_read - SPI synchronous write followed by read | |
569 | * @spi: device with which data will be exchanged | |
570 | * @txbuf: data to be written (need not be dma-safe) | |
571 | * @n_tx: size of txbuf, in bytes | |
572 | * @rxbuf: buffer into which data will be read | |
573 | * @n_rx: size of rxbuf, in bytes (need not be dma-safe) | |
33e34dc6 | 574 | * Context: can sleep |
8ae12a0d DB |
575 | * |
576 | * This performs a half duplex MicroWire style transaction with the | |
577 | * device, sending txbuf and then reading rxbuf. The return value | |
578 | * is zero for success, else a negative errno status code. | |
b885244e | 579 | * This call may only be used from a context that may sleep. |
8ae12a0d | 580 | * |
0c868461 | 581 | * Parameters to this routine are always copied using a small buffer; |
33e34dc6 DB |
582 | * portable code should never use this for more than 32 bytes. |
583 | * Performance-sensitive or bulk transfer code should instead use | |
0c868461 | 584 | * spi_{async,sync}() calls with dma-safe buffers. |
8ae12a0d DB |
585 | */ |
586 | int spi_write_then_read(struct spi_device *spi, | |
587 | const u8 *txbuf, unsigned n_tx, | |
588 | u8 *rxbuf, unsigned n_rx) | |
589 | { | |
068f4070 | 590 | static DEFINE_MUTEX(lock); |
8ae12a0d DB |
591 | |
592 | int status; | |
593 | struct spi_message message; | |
594 | struct spi_transfer x[2]; | |
595 | u8 *local_buf; | |
596 | ||
597 | /* Use preallocated DMA-safe buffer. We can't avoid copying here, | |
598 | * (as a pure convenience thing), but we can keep heap costs | |
599 | * out of the hot path ... | |
600 | */ | |
601 | if ((n_tx + n_rx) > SPI_BUFSIZ) | |
602 | return -EINVAL; | |
603 | ||
8275c642 VW |
604 | spi_message_init(&message); |
605 | memset(x, 0, sizeof x); | |
606 | if (n_tx) { | |
607 | x[0].len = n_tx; | |
608 | spi_message_add_tail(&x[0], &message); | |
609 | } | |
610 | if (n_rx) { | |
611 | x[1].len = n_rx; | |
612 | spi_message_add_tail(&x[1], &message); | |
613 | } | |
614 | ||
8ae12a0d | 615 | /* ... unless someone else is using the pre-allocated buffer */ |
068f4070 | 616 | if (!mutex_trylock(&lock)) { |
8ae12a0d DB |
617 | local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); |
618 | if (!local_buf) | |
619 | return -ENOMEM; | |
620 | } else | |
621 | local_buf = buf; | |
622 | ||
8ae12a0d DB |
623 | memcpy(local_buf, txbuf, n_tx); |
624 | x[0].tx_buf = local_buf; | |
8ae12a0d | 625 | x[1].rx_buf = local_buf + n_tx; |
8ae12a0d DB |
626 | |
627 | /* do the i/o */ | |
8ae12a0d | 628 | status = spi_sync(spi, &message); |
9b938b74 | 629 | if (status == 0) |
8ae12a0d | 630 | memcpy(rxbuf, x[1].rx_buf, n_rx); |
8ae12a0d DB |
631 | |
632 | if (x[0].tx_buf == buf) | |
068f4070 | 633 | mutex_unlock(&lock); |
8ae12a0d DB |
634 | else |
635 | kfree(local_buf); | |
636 | ||
637 | return status; | |
638 | } | |
639 | EXPORT_SYMBOL_GPL(spi_write_then_read); | |
640 | ||
641 | /*-------------------------------------------------------------------------*/ | |
642 | ||
643 | static int __init spi_init(void) | |
644 | { | |
b885244e DB |
645 | int status; |
646 | ||
e94b1766 | 647 | buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); |
b885244e DB |
648 | if (!buf) { |
649 | status = -ENOMEM; | |
650 | goto err0; | |
651 | } | |
652 | ||
653 | status = bus_register(&spi_bus_type); | |
654 | if (status < 0) | |
655 | goto err1; | |
8ae12a0d | 656 | |
b885244e DB |
657 | status = class_register(&spi_master_class); |
658 | if (status < 0) | |
659 | goto err2; | |
8ae12a0d | 660 | return 0; |
b885244e DB |
661 | |
662 | err2: | |
663 | bus_unregister(&spi_bus_type); | |
664 | err1: | |
665 | kfree(buf); | |
666 | buf = NULL; | |
667 | err0: | |
668 | return status; | |
8ae12a0d | 669 | } |
b885244e | 670 | |
8ae12a0d DB |
671 | /* board_info is normally registered in arch_initcall(), |
672 | * but even essential drivers wait till later | |
b885244e DB |
673 | * |
674 | * REVISIT only boardinfo really needs static linking. the rest (device and | |
675 | * driver registration) _could_ be dynamically linked (modular) ... costs | |
676 | * include needing to have boardinfo data structures be much more public. | |
8ae12a0d DB |
677 | */ |
678 | subsys_initcall(spi_init); | |
679 |