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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 | ||
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> | |
94040828 | 26 | #include <linux/mutex.h> |
8ae12a0d DB |
27 | #include <linux/spi/spi.h> |
28 | ||
29 | ||
b885244e DB |
30 | /* SPI bustype and spi_master class are registered after board init code |
31 | * provides the SPI device tables, ensuring that both are present by the | |
32 | * time controller driver registration causes spi_devices to "enumerate". | |
8ae12a0d DB |
33 | */ |
34 | static void spidev_release(struct device *dev) | |
35 | { | |
0ffa0285 | 36 | struct spi_device *spi = to_spi_device(dev); |
8ae12a0d DB |
37 | |
38 | /* spi masters may cleanup for released devices */ | |
39 | if (spi->master->cleanup) | |
40 | spi->master->cleanup(spi); | |
41 | ||
0c868461 | 42 | spi_master_put(spi->master); |
8ae12a0d DB |
43 | kfree(dev); |
44 | } | |
45 | ||
46 | static ssize_t | |
47 | modalias_show(struct device *dev, struct device_attribute *a, char *buf) | |
48 | { | |
49 | const struct spi_device *spi = to_spi_device(dev); | |
50 | ||
51 | return snprintf(buf, BUS_ID_SIZE + 1, "%s\n", spi->modalias); | |
52 | } | |
53 | ||
54 | static struct device_attribute spi_dev_attrs[] = { | |
55 | __ATTR_RO(modalias), | |
56 | __ATTR_NULL, | |
57 | }; | |
58 | ||
59 | /* modalias support makes "modprobe $MODALIAS" new-style hotplug work, | |
60 | * and the sysfs version makes coldplug work too. | |
61 | */ | |
62 | ||
63 | static int spi_match_device(struct device *dev, struct device_driver *drv) | |
64 | { | |
65 | const struct spi_device *spi = to_spi_device(dev); | |
66 | ||
67 | return strncmp(spi->modalias, drv->name, BUS_ID_SIZE) == 0; | |
68 | } | |
69 | ||
7eff2e7a | 70 | static int spi_uevent(struct device *dev, struct kobj_uevent_env *env) |
8ae12a0d DB |
71 | { |
72 | const struct spi_device *spi = to_spi_device(dev); | |
73 | ||
7eff2e7a | 74 | add_uevent_var(env, "MODALIAS=%s", spi->modalias); |
8ae12a0d DB |
75 | return 0; |
76 | } | |
77 | ||
78 | #ifdef CONFIG_PM | |
79 | ||
b885244e | 80 | /* |
8ae12a0d DB |
81 | * NOTE: the suspend() method for an spi_master controller driver |
82 | * should verify that all its child devices are marked as suspended; | |
83 | * suspend requests delivered through sysfs power/state files don't | |
84 | * enforce such constraints. | |
85 | */ | |
86 | static int spi_suspend(struct device *dev, pm_message_t message) | |
87 | { | |
b885244e DB |
88 | int value; |
89 | struct spi_driver *drv = to_spi_driver(dev->driver); | |
8ae12a0d | 90 | |
d2799f08 | 91 | if (!drv || !drv->suspend) |
8ae12a0d DB |
92 | return 0; |
93 | ||
94 | /* suspend will stop irqs and dma; no more i/o */ | |
b885244e | 95 | value = drv->suspend(to_spi_device(dev), message); |
8ae12a0d DB |
96 | if (value == 0) |
97 | dev->power.power_state = message; | |
98 | return value; | |
99 | } | |
100 | ||
101 | static int spi_resume(struct device *dev) | |
102 | { | |
b885244e DB |
103 | int value; |
104 | struct spi_driver *drv = to_spi_driver(dev->driver); | |
8ae12a0d | 105 | |
d2799f08 | 106 | if (!drv || !drv->resume) |
8ae12a0d DB |
107 | return 0; |
108 | ||
109 | /* resume may restart the i/o queue */ | |
b885244e | 110 | value = drv->resume(to_spi_device(dev)); |
8ae12a0d DB |
111 | if (value == 0) |
112 | dev->power.power_state = PMSG_ON; | |
113 | return value; | |
114 | } | |
115 | ||
116 | #else | |
117 | #define spi_suspend NULL | |
118 | #define spi_resume NULL | |
119 | #endif | |
120 | ||
121 | struct bus_type spi_bus_type = { | |
122 | .name = "spi", | |
123 | .dev_attrs = spi_dev_attrs, | |
124 | .match = spi_match_device, | |
125 | .uevent = spi_uevent, | |
126 | .suspend = spi_suspend, | |
127 | .resume = spi_resume, | |
128 | }; | |
129 | EXPORT_SYMBOL_GPL(spi_bus_type); | |
130 | ||
b885244e DB |
131 | |
132 | static int spi_drv_probe(struct device *dev) | |
133 | { | |
134 | const struct spi_driver *sdrv = to_spi_driver(dev->driver); | |
135 | ||
136 | return sdrv->probe(to_spi_device(dev)); | |
137 | } | |
138 | ||
139 | static int spi_drv_remove(struct device *dev) | |
140 | { | |
141 | const struct spi_driver *sdrv = to_spi_driver(dev->driver); | |
142 | ||
143 | return sdrv->remove(to_spi_device(dev)); | |
144 | } | |
145 | ||
146 | static void spi_drv_shutdown(struct device *dev) | |
147 | { | |
148 | const struct spi_driver *sdrv = to_spi_driver(dev->driver); | |
149 | ||
150 | sdrv->shutdown(to_spi_device(dev)); | |
151 | } | |
152 | ||
33e34dc6 DB |
153 | /** |
154 | * spi_register_driver - register a SPI driver | |
155 | * @sdrv: the driver to register | |
156 | * Context: can sleep | |
157 | */ | |
b885244e DB |
158 | int spi_register_driver(struct spi_driver *sdrv) |
159 | { | |
160 | sdrv->driver.bus = &spi_bus_type; | |
161 | if (sdrv->probe) | |
162 | sdrv->driver.probe = spi_drv_probe; | |
163 | if (sdrv->remove) | |
164 | sdrv->driver.remove = spi_drv_remove; | |
165 | if (sdrv->shutdown) | |
166 | sdrv->driver.shutdown = spi_drv_shutdown; | |
167 | return driver_register(&sdrv->driver); | |
168 | } | |
169 | EXPORT_SYMBOL_GPL(spi_register_driver); | |
170 | ||
8ae12a0d DB |
171 | /*-------------------------------------------------------------------------*/ |
172 | ||
173 | /* SPI devices should normally not be created by SPI device drivers; that | |
174 | * would make them board-specific. Similarly with SPI master drivers. | |
175 | * Device registration normally goes into like arch/.../mach.../board-YYY.c | |
176 | * with other readonly (flashable) information about mainboard devices. | |
177 | */ | |
178 | ||
179 | struct boardinfo { | |
180 | struct list_head list; | |
181 | unsigned n_board_info; | |
182 | struct spi_board_info board_info[0]; | |
183 | }; | |
184 | ||
185 | static LIST_HEAD(board_list); | |
94040828 | 186 | static DEFINE_MUTEX(board_lock); |
8ae12a0d DB |
187 | |
188 | ||
33e34dc6 DB |
189 | /** |
190 | * spi_new_device - instantiate one new SPI device | |
191 | * @master: Controller to which device is connected | |
192 | * @chip: Describes the SPI device | |
193 | * Context: can sleep | |
194 | * | |
195 | * On typical mainboards, this is purely internal; and it's not needed | |
8ae12a0d DB |
196 | * after board init creates the hard-wired devices. Some development |
197 | * platforms may not be able to use spi_register_board_info though, and | |
198 | * this is exported so that for example a USB or parport based adapter | |
199 | * driver could add devices (which it would learn about out-of-band). | |
082c8cb4 DB |
200 | * |
201 | * Returns the new device, or NULL. | |
8ae12a0d | 202 | */ |
e9d5a461 AB |
203 | struct spi_device *spi_new_device(struct spi_master *master, |
204 | struct spi_board_info *chip) | |
8ae12a0d DB |
205 | { |
206 | struct spi_device *proxy; | |
49dce689 | 207 | struct device *dev = master->dev.parent; |
8ae12a0d DB |
208 | int status; |
209 | ||
082c8cb4 DB |
210 | /* NOTE: caller did any chip->bus_num checks necessary. |
211 | * | |
212 | * Also, unless we change the return value convention to use | |
213 | * error-or-pointer (not NULL-or-pointer), troubleshootability | |
214 | * suggests syslogged diagnostics are best here (ugh). | |
215 | */ | |
216 | ||
217 | /* Chipselects are numbered 0..max; validate. */ | |
218 | if (chip->chip_select >= master->num_chipselect) { | |
219 | dev_err(dev, "cs%d > max %d\n", | |
220 | chip->chip_select, | |
221 | master->num_chipselect); | |
222 | return NULL; | |
223 | } | |
8ae12a0d | 224 | |
0c868461 | 225 | if (!spi_master_get(master)) |
8ae12a0d DB |
226 | return NULL; |
227 | ||
228 | proxy = kzalloc(sizeof *proxy, GFP_KERNEL); | |
229 | if (!proxy) { | |
230 | dev_err(dev, "can't alloc dev for cs%d\n", | |
231 | chip->chip_select); | |
232 | goto fail; | |
233 | } | |
234 | proxy->master = master; | |
235 | proxy->chip_select = chip->chip_select; | |
236 | proxy->max_speed_hz = chip->max_speed_hz; | |
980a01c9 | 237 | proxy->mode = chip->mode; |
8ae12a0d DB |
238 | proxy->irq = chip->irq; |
239 | proxy->modalias = chip->modalias; | |
240 | ||
241 | snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id, | |
49dce689 | 242 | "%s.%u", master->dev.bus_id, |
8ae12a0d DB |
243 | chip->chip_select); |
244 | proxy->dev.parent = dev; | |
245 | proxy->dev.bus = &spi_bus_type; | |
246 | proxy->dev.platform_data = (void *) chip->platform_data; | |
247 | proxy->controller_data = chip->controller_data; | |
248 | proxy->controller_state = NULL; | |
249 | proxy->dev.release = spidev_release; | |
250 | ||
082c8cb4 | 251 | /* drivers may modify this initial i/o setup */ |
8ae12a0d DB |
252 | status = master->setup(proxy); |
253 | if (status < 0) { | |
082c8cb4 | 254 | dev_err(dev, "can't %s %s, status %d\n", |
8ae12a0d DB |
255 | "setup", proxy->dev.bus_id, status); |
256 | goto fail; | |
257 | } | |
258 | ||
259 | /* driver core catches callers that misbehave by defining | |
260 | * devices that already exist. | |
261 | */ | |
262 | status = device_register(&proxy->dev); | |
263 | if (status < 0) { | |
082c8cb4 | 264 | dev_err(dev, "can't %s %s, status %d\n", |
8ae12a0d | 265 | "add", proxy->dev.bus_id, status); |
b885244e | 266 | goto fail; |
8ae12a0d DB |
267 | } |
268 | dev_dbg(dev, "registered child %s\n", proxy->dev.bus_id); | |
269 | return proxy; | |
b885244e DB |
270 | |
271 | fail: | |
0c868461 | 272 | spi_master_put(master); |
b885244e DB |
273 | kfree(proxy); |
274 | return NULL; | |
8ae12a0d DB |
275 | } |
276 | EXPORT_SYMBOL_GPL(spi_new_device); | |
277 | ||
33e34dc6 DB |
278 | /** |
279 | * spi_register_board_info - register SPI devices for a given board | |
280 | * @info: array of chip descriptors | |
281 | * @n: how many descriptors are provided | |
282 | * Context: can sleep | |
283 | * | |
8ae12a0d DB |
284 | * Board-specific early init code calls this (probably during arch_initcall) |
285 | * with segments of the SPI device table. Any device nodes are created later, | |
286 | * after the relevant parent SPI controller (bus_num) is defined. We keep | |
287 | * this table of devices forever, so that reloading a controller driver will | |
288 | * not make Linux forget about these hard-wired devices. | |
289 | * | |
290 | * Other code can also call this, e.g. a particular add-on board might provide | |
291 | * SPI devices through its expansion connector, so code initializing that board | |
292 | * would naturally declare its SPI devices. | |
293 | * | |
294 | * The board info passed can safely be __initdata ... but be careful of | |
295 | * any embedded pointers (platform_data, etc), they're copied as-is. | |
296 | */ | |
297 | int __init | |
298 | spi_register_board_info(struct spi_board_info const *info, unsigned n) | |
299 | { | |
300 | struct boardinfo *bi; | |
301 | ||
b885244e | 302 | bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL); |
8ae12a0d DB |
303 | if (!bi) |
304 | return -ENOMEM; | |
305 | bi->n_board_info = n; | |
b885244e | 306 | memcpy(bi->board_info, info, n * sizeof *info); |
8ae12a0d | 307 | |
94040828 | 308 | mutex_lock(&board_lock); |
8ae12a0d | 309 | list_add_tail(&bi->list, &board_list); |
94040828 | 310 | mutex_unlock(&board_lock); |
8ae12a0d DB |
311 | return 0; |
312 | } | |
8ae12a0d DB |
313 | |
314 | /* FIXME someone should add support for a __setup("spi", ...) that | |
315 | * creates board info from kernel command lines | |
316 | */ | |
317 | ||
149a6501 | 318 | static void scan_boardinfo(struct spi_master *master) |
8ae12a0d DB |
319 | { |
320 | struct boardinfo *bi; | |
8ae12a0d | 321 | |
94040828 | 322 | mutex_lock(&board_lock); |
8ae12a0d DB |
323 | list_for_each_entry(bi, &board_list, list) { |
324 | struct spi_board_info *chip = bi->board_info; | |
325 | unsigned n; | |
326 | ||
327 | for (n = bi->n_board_info; n > 0; n--, chip++) { | |
328 | if (chip->bus_num != master->bus_num) | |
329 | continue; | |
082c8cb4 DB |
330 | /* NOTE: this relies on spi_new_device to |
331 | * issue diagnostics when given bogus inputs | |
8ae12a0d | 332 | */ |
8ae12a0d DB |
333 | (void) spi_new_device(master, chip); |
334 | } | |
335 | } | |
94040828 | 336 | mutex_unlock(&board_lock); |
8ae12a0d DB |
337 | } |
338 | ||
339 | /*-------------------------------------------------------------------------*/ | |
340 | ||
49dce689 | 341 | static void spi_master_release(struct device *dev) |
8ae12a0d DB |
342 | { |
343 | struct spi_master *master; | |
344 | ||
49dce689 | 345 | master = container_of(dev, struct spi_master, dev); |
8ae12a0d DB |
346 | kfree(master); |
347 | } | |
348 | ||
349 | static struct class spi_master_class = { | |
350 | .name = "spi_master", | |
351 | .owner = THIS_MODULE, | |
49dce689 | 352 | .dev_release = spi_master_release, |
8ae12a0d DB |
353 | }; |
354 | ||
355 | ||
356 | /** | |
357 | * spi_alloc_master - allocate SPI master controller | |
358 | * @dev: the controller, possibly using the platform_bus | |
33e34dc6 | 359 | * @size: how much zeroed driver-private data to allocate; the pointer to this |
49dce689 | 360 | * memory is in the driver_data field of the returned device, |
0c868461 | 361 | * accessible with spi_master_get_devdata(). |
33e34dc6 | 362 | * Context: can sleep |
8ae12a0d DB |
363 | * |
364 | * This call is used only by SPI master controller drivers, which are the | |
365 | * only ones directly touching chip registers. It's how they allocate | |
ba1a0513 | 366 | * an spi_master structure, prior to calling spi_register_master(). |
8ae12a0d DB |
367 | * |
368 | * This must be called from context that can sleep. It returns the SPI | |
369 | * master structure on success, else NULL. | |
370 | * | |
371 | * The caller is responsible for assigning the bus number and initializing | |
ba1a0513 | 372 | * the master's methods before calling spi_register_master(); and (after errors |
0c868461 | 373 | * adding the device) calling spi_master_put() to prevent a memory leak. |
8ae12a0d | 374 | */ |
e9d5a461 | 375 | struct spi_master *spi_alloc_master(struct device *dev, unsigned size) |
8ae12a0d DB |
376 | { |
377 | struct spi_master *master; | |
378 | ||
0c868461 DB |
379 | if (!dev) |
380 | return NULL; | |
381 | ||
e94b1766 | 382 | master = kzalloc(size + sizeof *master, GFP_KERNEL); |
8ae12a0d DB |
383 | if (!master) |
384 | return NULL; | |
385 | ||
49dce689 TJ |
386 | device_initialize(&master->dev); |
387 | master->dev.class = &spi_master_class; | |
388 | master->dev.parent = get_device(dev); | |
0c868461 | 389 | spi_master_set_devdata(master, &master[1]); |
8ae12a0d DB |
390 | |
391 | return master; | |
392 | } | |
393 | EXPORT_SYMBOL_GPL(spi_alloc_master); | |
394 | ||
395 | /** | |
396 | * spi_register_master - register SPI master controller | |
397 | * @master: initialized master, originally from spi_alloc_master() | |
33e34dc6 | 398 | * Context: can sleep |
8ae12a0d DB |
399 | * |
400 | * SPI master controllers connect to their drivers using some non-SPI bus, | |
401 | * such as the platform bus. The final stage of probe() in that code | |
402 | * includes calling spi_register_master() to hook up to this SPI bus glue. | |
403 | * | |
404 | * SPI controllers use board specific (often SOC specific) bus numbers, | |
405 | * and board-specific addressing for SPI devices combines those numbers | |
406 | * with chip select numbers. Since SPI does not directly support dynamic | |
407 | * device identification, boards need configuration tables telling which | |
408 | * chip is at which address. | |
409 | * | |
410 | * This must be called from context that can sleep. It returns zero on | |
411 | * success, else a negative error code (dropping the master's refcount). | |
0c868461 DB |
412 | * After a successful return, the caller is responsible for calling |
413 | * spi_unregister_master(). | |
8ae12a0d | 414 | */ |
e9d5a461 | 415 | int spi_register_master(struct spi_master *master) |
8ae12a0d | 416 | { |
e44a45ae | 417 | static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1); |
49dce689 | 418 | struct device *dev = master->dev.parent; |
8ae12a0d DB |
419 | int status = -ENODEV; |
420 | int dynamic = 0; | |
421 | ||
0c868461 DB |
422 | if (!dev) |
423 | return -ENODEV; | |
424 | ||
082c8cb4 DB |
425 | /* even if it's just one always-selected device, there must |
426 | * be at least one chipselect | |
427 | */ | |
428 | if (master->num_chipselect == 0) | |
429 | return -EINVAL; | |
430 | ||
8ae12a0d | 431 | /* convention: dynamically assigned bus IDs count down from the max */ |
a020ed75 | 432 | if (master->bus_num < 0) { |
082c8cb4 DB |
433 | /* FIXME switch to an IDR based scheme, something like |
434 | * I2C now uses, so we can't run out of "dynamic" IDs | |
435 | */ | |
8ae12a0d | 436 | master->bus_num = atomic_dec_return(&dyn_bus_id); |
b885244e | 437 | dynamic = 1; |
8ae12a0d DB |
438 | } |
439 | ||
440 | /* register the device, then userspace will see it. | |
441 | * registration fails if the bus ID is in use. | |
442 | */ | |
49dce689 | 443 | snprintf(master->dev.bus_id, sizeof master->dev.bus_id, |
8ae12a0d | 444 | "spi%u", master->bus_num); |
49dce689 | 445 | status = device_add(&master->dev); |
b885244e | 446 | if (status < 0) |
8ae12a0d | 447 | goto done; |
49dce689 | 448 | dev_dbg(dev, "registered master %s%s\n", master->dev.bus_id, |
8ae12a0d DB |
449 | dynamic ? " (dynamic)" : ""); |
450 | ||
451 | /* populate children from any spi device tables */ | |
452 | scan_boardinfo(master); | |
453 | status = 0; | |
454 | done: | |
455 | return status; | |
456 | } | |
457 | EXPORT_SYMBOL_GPL(spi_register_master); | |
458 | ||
459 | ||
350d0076 | 460 | static int __unregister(struct device *dev, void *master_dev) |
8ae12a0d DB |
461 | { |
462 | /* note: before about 2.6.14-rc1 this would corrupt memory: */ | |
350d0076 AN |
463 | if (dev != master_dev) |
464 | spi_unregister_device(to_spi_device(dev)); | |
8ae12a0d DB |
465 | return 0; |
466 | } | |
467 | ||
468 | /** | |
469 | * spi_unregister_master - unregister SPI master controller | |
470 | * @master: the master being unregistered | |
33e34dc6 | 471 | * Context: can sleep |
8ae12a0d DB |
472 | * |
473 | * This call is used only by SPI master controller drivers, which are the | |
474 | * only ones directly touching chip registers. | |
475 | * | |
476 | * This must be called from context that can sleep. | |
477 | */ | |
478 | void spi_unregister_master(struct spi_master *master) | |
479 | { | |
89fc9a1a JG |
480 | int dummy; |
481 | ||
350d0076 AN |
482 | dummy = device_for_each_child(master->dev.parent, &master->dev, |
483 | __unregister); | |
49dce689 | 484 | device_unregister(&master->dev); |
8ae12a0d DB |
485 | } |
486 | EXPORT_SYMBOL_GPL(spi_unregister_master); | |
487 | ||
488 | /** | |
489 | * spi_busnum_to_master - look up master associated with bus_num | |
490 | * @bus_num: the master's bus number | |
33e34dc6 | 491 | * Context: can sleep |
8ae12a0d DB |
492 | * |
493 | * This call may be used with devices that are registered after | |
494 | * arch init time. It returns a refcounted pointer to the relevant | |
495 | * spi_master (which the caller must release), or NULL if there is | |
496 | * no such master registered. | |
497 | */ | |
498 | struct spi_master *spi_busnum_to_master(u16 bus_num) | |
499 | { | |
49dce689 | 500 | struct device *dev; |
1e9a51dc AN |
501 | struct spi_master *master = NULL; |
502 | struct spi_master *m; | |
503 | ||
504 | down(&spi_master_class.sem); | |
49dce689 TJ |
505 | list_for_each_entry(dev, &spi_master_class.children, node) { |
506 | m = container_of(dev, struct spi_master, dev); | |
1e9a51dc AN |
507 | if (m->bus_num == bus_num) { |
508 | master = spi_master_get(m); | |
509 | break; | |
510 | } | |
511 | } | |
512 | up(&spi_master_class.sem); | |
513 | return master; | |
8ae12a0d DB |
514 | } |
515 | EXPORT_SYMBOL_GPL(spi_busnum_to_master); | |
516 | ||
517 | ||
518 | /*-------------------------------------------------------------------------*/ | |
519 | ||
5d870c8e AM |
520 | static void spi_complete(void *arg) |
521 | { | |
522 | complete(arg); | |
523 | } | |
524 | ||
8ae12a0d DB |
525 | /** |
526 | * spi_sync - blocking/synchronous SPI data transfers | |
527 | * @spi: device with which data will be exchanged | |
528 | * @message: describes the data transfers | |
33e34dc6 | 529 | * Context: can sleep |
8ae12a0d DB |
530 | * |
531 | * This call may only be used from a context that may sleep. The sleep | |
532 | * is non-interruptible, and has no timeout. Low-overhead controller | |
533 | * drivers may DMA directly into and out of the message buffers. | |
534 | * | |
535 | * Note that the SPI device's chip select is active during the message, | |
536 | * and then is normally disabled between messages. Drivers for some | |
537 | * frequently-used devices may want to minimize costs of selecting a chip, | |
538 | * by leaving it selected in anticipation that the next message will go | |
539 | * to the same chip. (That may increase power usage.) | |
540 | * | |
0c868461 DB |
541 | * Also, the caller is guaranteeing that the memory associated with the |
542 | * message will not be freed before this call returns. | |
543 | * | |
9b938b74 | 544 | * It returns zero on success, else a negative error code. |
8ae12a0d DB |
545 | */ |
546 | int spi_sync(struct spi_device *spi, struct spi_message *message) | |
547 | { | |
60be6b9a | 548 | DECLARE_COMPLETION_ONSTACK(done); |
8ae12a0d DB |
549 | int status; |
550 | ||
5d870c8e | 551 | message->complete = spi_complete; |
8ae12a0d DB |
552 | message->context = &done; |
553 | status = spi_async(spi, message); | |
9b938b74 | 554 | if (status == 0) { |
8ae12a0d | 555 | wait_for_completion(&done); |
9b938b74 MP |
556 | status = message->status; |
557 | } | |
8ae12a0d DB |
558 | message->context = NULL; |
559 | return status; | |
560 | } | |
561 | EXPORT_SYMBOL_GPL(spi_sync); | |
562 | ||
a9948b61 DB |
563 | /* portable code must never pass more than 32 bytes */ |
564 | #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES) | |
8ae12a0d DB |
565 | |
566 | static u8 *buf; | |
567 | ||
568 | /** | |
569 | * spi_write_then_read - SPI synchronous write followed by read | |
570 | * @spi: device with which data will be exchanged | |
571 | * @txbuf: data to be written (need not be dma-safe) | |
572 | * @n_tx: size of txbuf, in bytes | |
573 | * @rxbuf: buffer into which data will be read | |
574 | * @n_rx: size of rxbuf, in bytes (need not be dma-safe) | |
33e34dc6 | 575 | * Context: can sleep |
8ae12a0d DB |
576 | * |
577 | * This performs a half duplex MicroWire style transaction with the | |
578 | * device, sending txbuf and then reading rxbuf. The return value | |
579 | * is zero for success, else a negative errno status code. | |
b885244e | 580 | * This call may only be used from a context that may sleep. |
8ae12a0d | 581 | * |
0c868461 | 582 | * Parameters to this routine are always copied using a small buffer; |
33e34dc6 DB |
583 | * portable code should never use this for more than 32 bytes. |
584 | * Performance-sensitive or bulk transfer code should instead use | |
0c868461 | 585 | * spi_{async,sync}() calls with dma-safe buffers. |
8ae12a0d DB |
586 | */ |
587 | int spi_write_then_read(struct spi_device *spi, | |
588 | const u8 *txbuf, unsigned n_tx, | |
589 | u8 *rxbuf, unsigned n_rx) | |
590 | { | |
068f4070 | 591 | static DEFINE_MUTEX(lock); |
8ae12a0d DB |
592 | |
593 | int status; | |
594 | struct spi_message message; | |
595 | struct spi_transfer x[2]; | |
596 | u8 *local_buf; | |
597 | ||
598 | /* Use preallocated DMA-safe buffer. We can't avoid copying here, | |
599 | * (as a pure convenience thing), but we can keep heap costs | |
600 | * out of the hot path ... | |
601 | */ | |
602 | if ((n_tx + n_rx) > SPI_BUFSIZ) | |
603 | return -EINVAL; | |
604 | ||
8275c642 VW |
605 | spi_message_init(&message); |
606 | memset(x, 0, sizeof x); | |
607 | if (n_tx) { | |
608 | x[0].len = n_tx; | |
609 | spi_message_add_tail(&x[0], &message); | |
610 | } | |
611 | if (n_rx) { | |
612 | x[1].len = n_rx; | |
613 | spi_message_add_tail(&x[1], &message); | |
614 | } | |
615 | ||
8ae12a0d | 616 | /* ... unless someone else is using the pre-allocated buffer */ |
068f4070 | 617 | if (!mutex_trylock(&lock)) { |
8ae12a0d DB |
618 | local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); |
619 | if (!local_buf) | |
620 | return -ENOMEM; | |
621 | } else | |
622 | local_buf = buf; | |
623 | ||
8ae12a0d DB |
624 | memcpy(local_buf, txbuf, n_tx); |
625 | x[0].tx_buf = local_buf; | |
8ae12a0d | 626 | x[1].rx_buf = local_buf + n_tx; |
8ae12a0d DB |
627 | |
628 | /* do the i/o */ | |
8ae12a0d | 629 | status = spi_sync(spi, &message); |
9b938b74 | 630 | if (status == 0) |
8ae12a0d | 631 | memcpy(rxbuf, x[1].rx_buf, n_rx); |
8ae12a0d DB |
632 | |
633 | if (x[0].tx_buf == buf) | |
068f4070 | 634 | mutex_unlock(&lock); |
8ae12a0d DB |
635 | else |
636 | kfree(local_buf); | |
637 | ||
638 | return status; | |
639 | } | |
640 | EXPORT_SYMBOL_GPL(spi_write_then_read); | |
641 | ||
642 | /*-------------------------------------------------------------------------*/ | |
643 | ||
644 | static int __init spi_init(void) | |
645 | { | |
b885244e DB |
646 | int status; |
647 | ||
e94b1766 | 648 | buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); |
b885244e DB |
649 | if (!buf) { |
650 | status = -ENOMEM; | |
651 | goto err0; | |
652 | } | |
653 | ||
654 | status = bus_register(&spi_bus_type); | |
655 | if (status < 0) | |
656 | goto err1; | |
8ae12a0d | 657 | |
b885244e DB |
658 | status = class_register(&spi_master_class); |
659 | if (status < 0) | |
660 | goto err2; | |
8ae12a0d | 661 | return 0; |
b885244e DB |
662 | |
663 | err2: | |
664 | bus_unregister(&spi_bus_type); | |
665 | err1: | |
666 | kfree(buf); | |
667 | buf = NULL; | |
668 | err0: | |
669 | return status; | |
8ae12a0d | 670 | } |
b885244e | 671 | |
8ae12a0d DB |
672 | /* board_info is normally registered in arch_initcall(), |
673 | * but even essential drivers wait till later | |
b885244e DB |
674 | * |
675 | * REVISIT only boardinfo really needs static linking. the rest (device and | |
676 | * driver registration) _could_ be dynamically linked (modular) ... costs | |
677 | * include needing to have boardinfo data structures be much more public. | |
8ae12a0d DB |
678 | */ |
679 | subsys_initcall(spi_init); | |
680 |