]>
Commit | Line | Data |
---|---|---|
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> | |
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 | { | |
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 | ||
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 | ||
69 | static 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 | ||
b885244e | 82 | /* |
8ae12a0d DB |
83 | * 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 | */ | |
88 | static int spi_suspend(struct device *dev, pm_message_t message) | |
89 | { | |
b885244e DB |
90 | int value; |
91 | struct spi_driver *drv = to_spi_driver(dev->driver); | |
8ae12a0d | 92 | |
d2799f08 | 93 | if (!drv || !drv->suspend) |
8ae12a0d DB |
94 | return 0; |
95 | ||
96 | /* suspend will stop irqs and dma; no more i/o */ | |
b885244e | 97 | value = drv->suspend(to_spi_device(dev), message); |
8ae12a0d DB |
98 | if (value == 0) |
99 | dev->power.power_state = message; | |
100 | return value; | |
101 | } | |
102 | ||
103 | static int spi_resume(struct device *dev) | |
104 | { | |
b885244e DB |
105 | int value; |
106 | struct spi_driver *drv = to_spi_driver(dev->driver); | |
8ae12a0d | 107 | |
d2799f08 | 108 | if (!drv || !drv->resume) |
8ae12a0d DB |
109 | return 0; |
110 | ||
111 | /* resume may restart the i/o queue */ | |
b885244e | 112 | value = drv->resume(to_spi_device(dev)); |
8ae12a0d DB |
113 | 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 | ||
123 | struct 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 | }; | |
131 | EXPORT_SYMBOL_GPL(spi_bus_type); | |
132 | ||
b885244e DB |
133 | |
134 | static 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 | ||
141 | static 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 | ||
148 | static 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 | ||
155 | int 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 | } | |
166 | EXPORT_SYMBOL_GPL(spi_register_driver); | |
167 | ||
8ae12a0d DB |
168 | /*-------------------------------------------------------------------------*/ |
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 | ||
176 | struct boardinfo { | |
177 | struct list_head list; | |
178 | unsigned n_board_info; | |
179 | struct spi_board_info board_info[0]; | |
180 | }; | |
181 | ||
182 | static LIST_HEAD(board_list); | |
183 | static 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 | */ | |
192 | struct spi_device *__init_or_module | |
193 | spi_new_device(struct spi_master *master, struct spi_board_info *chip) | |
194 | { | |
195 | struct spi_device *proxy; | |
2943ecf2 | 196 | struct device *dev = &master->dev; |
8ae12a0d DB |
197 | int status; |
198 | ||
199 | /* NOTE: caller did any chip->bus_num checks necessary */ | |
200 | ||
0c868461 | 201 | if (!spi_master_get(master)) |
8ae12a0d DB |
202 | 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; | |
980a01c9 | 213 | proxy->mode = chip->mode; |
8ae12a0d DB |
214 | proxy->irq = chip->irq; |
215 | proxy->modalias = chip->modalias; | |
216 | ||
217 | snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id, | |
2943ecf2 | 218 | "%s.%u", master->dev.bus_id, |
8ae12a0d DB |
219 | chip->chip_select); |
220 | proxy->dev.parent = dev; | |
221 | proxy->dev.bus = &spi_bus_type; | |
222 | proxy->dev.platform_data = (void *) chip->platform_data; | |
223 | proxy->controller_data = chip->controller_data; | |
224 | proxy->controller_state = NULL; | |
225 | proxy->dev.release = spidev_release; | |
226 | ||
227 | /* drivers may modify this default i/o setup */ | |
228 | status = master->setup(proxy); | |
229 | if (status < 0) { | |
230 | dev_dbg(dev, "can't %s %s, status %d\n", | |
231 | "setup", proxy->dev.bus_id, status); | |
232 | goto fail; | |
233 | } | |
234 | ||
235 | /* driver core catches callers that misbehave by defining | |
236 | * devices that already exist. | |
237 | */ | |
238 | status = device_register(&proxy->dev); | |
239 | if (status < 0) { | |
240 | dev_dbg(dev, "can't %s %s, status %d\n", | |
241 | "add", proxy->dev.bus_id, status); | |
b885244e | 242 | goto fail; |
8ae12a0d DB |
243 | } |
244 | dev_dbg(dev, "registered child %s\n", proxy->dev.bus_id); | |
245 | return proxy; | |
b885244e DB |
246 | |
247 | fail: | |
0c868461 | 248 | spi_master_put(master); |
b885244e DB |
249 | kfree(proxy); |
250 | return NULL; | |
8ae12a0d DB |
251 | } |
252 | EXPORT_SYMBOL_GPL(spi_new_device); | |
253 | ||
254 | /* | |
255 | * Board-specific early init code calls this (probably during arch_initcall) | |
256 | * with segments of the SPI device table. Any device nodes are created later, | |
257 | * after the relevant parent SPI controller (bus_num) is defined. We keep | |
258 | * this table of devices forever, so that reloading a controller driver will | |
259 | * not make Linux forget about these hard-wired devices. | |
260 | * | |
261 | * Other code can also call this, e.g. a particular add-on board might provide | |
262 | * SPI devices through its expansion connector, so code initializing that board | |
263 | * would naturally declare its SPI devices. | |
264 | * | |
265 | * The board info passed can safely be __initdata ... but be careful of | |
266 | * any embedded pointers (platform_data, etc), they're copied as-is. | |
267 | */ | |
268 | int __init | |
269 | spi_register_board_info(struct spi_board_info const *info, unsigned n) | |
270 | { | |
271 | struct boardinfo *bi; | |
272 | ||
b885244e | 273 | bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL); |
8ae12a0d DB |
274 | if (!bi) |
275 | return -ENOMEM; | |
276 | bi->n_board_info = n; | |
b885244e | 277 | memcpy(bi->board_info, info, n * sizeof *info); |
8ae12a0d DB |
278 | |
279 | down(&board_lock); | |
280 | list_add_tail(&bi->list, &board_list); | |
281 | up(&board_lock); | |
282 | return 0; | |
283 | } | |
8ae12a0d DB |
284 | |
285 | /* FIXME someone should add support for a __setup("spi", ...) that | |
286 | * creates board info from kernel command lines | |
287 | */ | |
288 | ||
289 | static void __init_or_module | |
290 | scan_boardinfo(struct spi_master *master) | |
291 | { | |
292 | struct boardinfo *bi; | |
2943ecf2 | 293 | struct device *dev = master->dev.parent; |
8ae12a0d DB |
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 | ||
2943ecf2 | 322 | static void spi_master_release(struct device *dev) |
8ae12a0d DB |
323 | { |
324 | struct spi_master *master; | |
325 | ||
2943ecf2 | 326 | master = container_of(dev, struct spi_master, dev); |
8ae12a0d DB |
327 | kfree(master); |
328 | } | |
329 | ||
330 | static struct class spi_master_class = { | |
331 | .name = "spi_master", | |
332 | .owner = THIS_MODULE, | |
2943ecf2 | 333 | .dev_release = spi_master_release, |
8ae12a0d DB |
334 | }; |
335 | ||
336 | ||
337 | /** | |
338 | * spi_alloc_master - allocate SPI master controller | |
339 | * @dev: the controller, possibly using the platform_bus | |
0c868461 | 340 | * @size: how much driver-private data to preallocate; the pointer to this |
ba1a0513 | 341 | * memory is in the class_data field of the returned class_device, |
0c868461 | 342 | * accessible with spi_master_get_devdata(). |
8ae12a0d DB |
343 | * |
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 | |
ba1a0513 | 346 | * an spi_master structure, prior to calling spi_register_master(). |
8ae12a0d DB |
347 | * |
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 | |
ba1a0513 | 352 | * the master's methods before calling spi_register_master(); and (after errors |
0c868461 | 353 | * adding the device) calling spi_master_put() to prevent a memory leak. |
8ae12a0d DB |
354 | */ |
355 | struct spi_master * __init_or_module | |
356 | spi_alloc_master(struct device *dev, unsigned size) | |
357 | { | |
358 | struct spi_master *master; | |
359 | ||
0c868461 DB |
360 | if (!dev) |
361 | return NULL; | |
362 | ||
e94b1766 | 363 | master = kzalloc(size + sizeof *master, GFP_KERNEL); |
8ae12a0d DB |
364 | if (!master) |
365 | return NULL; | |
366 | ||
2943ecf2 GKH |
367 | device_initialize(&master->dev); |
368 | master->dev.class = &spi_master_class; | |
369 | master->dev.parent = get_device(dev); | |
0c868461 | 370 | spi_master_set_devdata(master, &master[1]); |
8ae12a0d DB |
371 | |
372 | return master; | |
373 | } | |
374 | EXPORT_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). | |
0c868461 DB |
392 | * After a successful return, the caller is responsible for calling |
393 | * spi_unregister_master(). | |
8ae12a0d DB |
394 | */ |
395 | int __init_or_module | |
396 | spi_register_master(struct spi_master *master) | |
397 | { | |
a020ed75 | 398 | static atomic_t dyn_bus_id = ATOMIC_INIT((1<<16) - 1); |
2943ecf2 | 399 | struct device *dev = master->dev.parent; |
8ae12a0d DB |
400 | int status = -ENODEV; |
401 | int dynamic = 0; | |
402 | ||
0c868461 DB |
403 | if (!dev) |
404 | return -ENODEV; | |
405 | ||
8ae12a0d | 406 | /* convention: dynamically assigned bus IDs count down from the max */ |
a020ed75 | 407 | if (master->bus_num < 0) { |
8ae12a0d | 408 | master->bus_num = atomic_dec_return(&dyn_bus_id); |
b885244e | 409 | dynamic = 1; |
8ae12a0d DB |
410 | } |
411 | ||
412 | /* register the device, then userspace will see it. | |
413 | * registration fails if the bus ID is in use. | |
414 | */ | |
2943ecf2 | 415 | snprintf(master->dev.bus_id, sizeof master->dev.bus_id, |
8ae12a0d | 416 | "spi%u", master->bus_num); |
2943ecf2 | 417 | status = device_add(&master->dev); |
b885244e | 418 | if (status < 0) |
8ae12a0d | 419 | goto done; |
2943ecf2 | 420 | dev_dbg(dev, "registered master %s%s\n", master->dev.bus_id, |
8ae12a0d DB |
421 | dynamic ? " (dynamic)" : ""); |
422 | ||
423 | /* populate children from any spi device tables */ | |
424 | scan_boardinfo(master); | |
425 | status = 0; | |
426 | done: | |
427 | return status; | |
428 | } | |
429 | EXPORT_SYMBOL_GPL(spi_register_master); | |
430 | ||
431 | ||
432 | static int __unregister(struct device *dev, void *unused) | |
433 | { | |
434 | /* note: before about 2.6.14-rc1 this would corrupt memory: */ | |
0c868461 | 435 | spi_unregister_device(to_spi_device(dev)); |
8ae12a0d DB |
436 | 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 | */ | |
448 | void spi_unregister_master(struct spi_master *master) | |
449 | { | |
89fc9a1a JG |
450 | int dummy; |
451 | ||
2943ecf2 GKH |
452 | dummy = device_for_each_child(&master->dev, NULL, __unregister); |
453 | device_unregister(&master->dev); | |
8ae12a0d DB |
454 | } |
455 | EXPORT_SYMBOL_GPL(spi_unregister_master); | |
456 | ||
457 | /** | |
458 | * spi_busnum_to_master - look up master associated with bus_num | |
459 | * @bus_num: the master's bus number | |
460 | * | |
461 | * This call may be used with devices that are registered after | |
462 | * arch init time. It returns a refcounted pointer to the relevant | |
463 | * spi_master (which the caller must release), or NULL if there is | |
464 | * no such master registered. | |
465 | */ | |
466 | struct spi_master *spi_busnum_to_master(u16 bus_num) | |
467 | { | |
1e9a51dc AN |
468 | struct class_device *cdev; |
469 | struct spi_master *master = NULL; | |
470 | struct spi_master *m; | |
471 | ||
472 | down(&spi_master_class.sem); | |
473 | list_for_each_entry(cdev, &spi_master_class.children, node) { | |
2943ecf2 | 474 | m = container_of(cdev, struct spi_master, dev.kobj); |
1e9a51dc AN |
475 | if (m->bus_num == bus_num) { |
476 | master = spi_master_get(m); | |
477 | break; | |
478 | } | |
479 | } | |
480 | up(&spi_master_class.sem); | |
481 | return master; | |
8ae12a0d DB |
482 | } |
483 | EXPORT_SYMBOL_GPL(spi_busnum_to_master); | |
484 | ||
485 | ||
486 | /*-------------------------------------------------------------------------*/ | |
487 | ||
5d870c8e AM |
488 | static void spi_complete(void *arg) |
489 | { | |
490 | complete(arg); | |
491 | } | |
492 | ||
8ae12a0d DB |
493 | /** |
494 | * spi_sync - blocking/synchronous SPI data transfers | |
495 | * @spi: device with which data will be exchanged | |
496 | * @message: describes the data transfers | |
497 | * | |
498 | * This call may only be used from a context that may sleep. The sleep | |
499 | * is non-interruptible, and has no timeout. Low-overhead controller | |
500 | * drivers may DMA directly into and out of the message buffers. | |
501 | * | |
502 | * Note that the SPI device's chip select is active during the message, | |
503 | * and then is normally disabled between messages. Drivers for some | |
504 | * frequently-used devices may want to minimize costs of selecting a chip, | |
505 | * by leaving it selected in anticipation that the next message will go | |
506 | * to the same chip. (That may increase power usage.) | |
507 | * | |
0c868461 DB |
508 | * Also, the caller is guaranteeing that the memory associated with the |
509 | * message will not be freed before this call returns. | |
510 | * | |
8ae12a0d DB |
511 | * The return value is a negative error code if the message could not be |
512 | * submitted, else zero. When the value is zero, then message->status is | |
513 | * also defined: it's the completion code for the transfer, either zero | |
514 | * or a negative error code from the controller driver. | |
515 | */ | |
516 | int spi_sync(struct spi_device *spi, struct spi_message *message) | |
517 | { | |
60be6b9a | 518 | DECLARE_COMPLETION_ONSTACK(done); |
8ae12a0d DB |
519 | int status; |
520 | ||
5d870c8e | 521 | message->complete = spi_complete; |
8ae12a0d DB |
522 | message->context = &done; |
523 | status = spi_async(spi, message); | |
524 | if (status == 0) | |
525 | wait_for_completion(&done); | |
526 | message->context = NULL; | |
527 | return status; | |
528 | } | |
529 | EXPORT_SYMBOL_GPL(spi_sync); | |
530 | ||
a9948b61 DB |
531 | /* portable code must never pass more than 32 bytes */ |
532 | #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES) | |
8ae12a0d DB |
533 | |
534 | static u8 *buf; | |
535 | ||
536 | /** | |
537 | * spi_write_then_read - SPI synchronous write followed by read | |
538 | * @spi: device with which data will be exchanged | |
539 | * @txbuf: data to be written (need not be dma-safe) | |
540 | * @n_tx: size of txbuf, in bytes | |
541 | * @rxbuf: buffer into which data will be read | |
542 | * @n_rx: size of rxbuf, in bytes (need not be dma-safe) | |
543 | * | |
544 | * This performs a half duplex MicroWire style transaction with the | |
545 | * device, sending txbuf and then reading rxbuf. The return value | |
546 | * is zero for success, else a negative errno status code. | |
b885244e | 547 | * This call may only be used from a context that may sleep. |
8ae12a0d | 548 | * |
0c868461 DB |
549 | * Parameters to this routine are always copied using a small buffer; |
550 | * performance-sensitive or bulk transfer code should instead use | |
551 | * spi_{async,sync}() calls with dma-safe buffers. | |
8ae12a0d DB |
552 | */ |
553 | int spi_write_then_read(struct spi_device *spi, | |
554 | const u8 *txbuf, unsigned n_tx, | |
555 | u8 *rxbuf, unsigned n_rx) | |
556 | { | |
557 | static DECLARE_MUTEX(lock); | |
558 | ||
559 | int status; | |
560 | struct spi_message message; | |
561 | struct spi_transfer x[2]; | |
562 | u8 *local_buf; | |
563 | ||
564 | /* Use preallocated DMA-safe buffer. We can't avoid copying here, | |
565 | * (as a pure convenience thing), but we can keep heap costs | |
566 | * out of the hot path ... | |
567 | */ | |
568 | if ((n_tx + n_rx) > SPI_BUFSIZ) | |
569 | return -EINVAL; | |
570 | ||
8275c642 VW |
571 | spi_message_init(&message); |
572 | memset(x, 0, sizeof x); | |
573 | if (n_tx) { | |
574 | x[0].len = n_tx; | |
575 | spi_message_add_tail(&x[0], &message); | |
576 | } | |
577 | if (n_rx) { | |
578 | x[1].len = n_rx; | |
579 | spi_message_add_tail(&x[1], &message); | |
580 | } | |
581 | ||
8ae12a0d DB |
582 | /* ... unless someone else is using the pre-allocated buffer */ |
583 | if (down_trylock(&lock)) { | |
584 | local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); | |
585 | if (!local_buf) | |
586 | return -ENOMEM; | |
587 | } else | |
588 | local_buf = buf; | |
589 | ||
8ae12a0d DB |
590 | memcpy(local_buf, txbuf, n_tx); |
591 | x[0].tx_buf = local_buf; | |
8ae12a0d | 592 | x[1].rx_buf = local_buf + n_tx; |
8ae12a0d DB |
593 | |
594 | /* do the i/o */ | |
8ae12a0d DB |
595 | status = spi_sync(spi, &message); |
596 | if (status == 0) { | |
597 | memcpy(rxbuf, x[1].rx_buf, n_rx); | |
598 | status = message.status; | |
599 | } | |
600 | ||
601 | if (x[0].tx_buf == buf) | |
602 | up(&lock); | |
603 | else | |
604 | kfree(local_buf); | |
605 | ||
606 | return status; | |
607 | } | |
608 | EXPORT_SYMBOL_GPL(spi_write_then_read); | |
609 | ||
610 | /*-------------------------------------------------------------------------*/ | |
611 | ||
612 | static int __init spi_init(void) | |
613 | { | |
b885244e DB |
614 | int status; |
615 | ||
e94b1766 | 616 | buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); |
b885244e DB |
617 | if (!buf) { |
618 | status = -ENOMEM; | |
619 | goto err0; | |
620 | } | |
621 | ||
622 | status = bus_register(&spi_bus_type); | |
623 | if (status < 0) | |
624 | goto err1; | |
8ae12a0d | 625 | |
b885244e DB |
626 | status = class_register(&spi_master_class); |
627 | if (status < 0) | |
628 | goto err2; | |
8ae12a0d | 629 | return 0; |
b885244e DB |
630 | |
631 | err2: | |
632 | bus_unregister(&spi_bus_type); | |
633 | err1: | |
634 | kfree(buf); | |
635 | buf = NULL; | |
636 | err0: | |
637 | return status; | |
8ae12a0d | 638 | } |
b885244e | 639 | |
8ae12a0d DB |
640 | /* board_info is normally registered in arch_initcall(), |
641 | * but even essential drivers wait till later | |
b885244e DB |
642 | * |
643 | * REVISIT only boardinfo really needs static linking. the rest (device and | |
644 | * driver registration) _could_ be dynamically linked (modular) ... costs | |
645 | * include needing to have boardinfo data structures be much more public. | |
8ae12a0d DB |
646 | */ |
647 | subsys_initcall(spi_init); | |
648 |