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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 | ||
70 | static int spi_uevent(struct device *dev, char **envp, int num_envp, | |
71 | char *buffer, int buffer_size) | |
72 | { | |
73 | const struct spi_device *spi = to_spi_device(dev); | |
74 | ||
75 | envp[0] = buffer; | |
76 | snprintf(buffer, buffer_size, "MODALIAS=%s", spi->modalias); | |
77 | envp[1] = NULL; | |
78 | return 0; | |
79 | } | |
80 | ||
81 | #ifdef CONFIG_PM | |
82 | ||
b885244e | 83 | /* |
8ae12a0d DB |
84 | * NOTE: the suspend() method for an spi_master controller driver |
85 | * should verify that all its child devices are marked as suspended; | |
86 | * suspend requests delivered through sysfs power/state files don't | |
87 | * enforce such constraints. | |
88 | */ | |
89 | static int spi_suspend(struct device *dev, pm_message_t message) | |
90 | { | |
b885244e DB |
91 | int value; |
92 | struct spi_driver *drv = to_spi_driver(dev->driver); | |
8ae12a0d | 93 | |
d2799f08 | 94 | if (!drv || !drv->suspend) |
8ae12a0d DB |
95 | return 0; |
96 | ||
97 | /* suspend will stop irqs and dma; no more i/o */ | |
b885244e | 98 | value = drv->suspend(to_spi_device(dev), message); |
8ae12a0d DB |
99 | if (value == 0) |
100 | dev->power.power_state = message; | |
101 | return value; | |
102 | } | |
103 | ||
104 | static int spi_resume(struct device *dev) | |
105 | { | |
b885244e DB |
106 | int value; |
107 | struct spi_driver *drv = to_spi_driver(dev->driver); | |
8ae12a0d | 108 | |
d2799f08 | 109 | if (!drv || !drv->resume) |
8ae12a0d DB |
110 | return 0; |
111 | ||
112 | /* resume may restart the i/o queue */ | |
b885244e | 113 | value = drv->resume(to_spi_device(dev)); |
8ae12a0d DB |
114 | if (value == 0) |
115 | dev->power.power_state = PMSG_ON; | |
116 | return value; | |
117 | } | |
118 | ||
119 | #else | |
120 | #define spi_suspend NULL | |
121 | #define spi_resume NULL | |
122 | #endif | |
123 | ||
124 | struct bus_type spi_bus_type = { | |
125 | .name = "spi", | |
126 | .dev_attrs = spi_dev_attrs, | |
127 | .match = spi_match_device, | |
128 | .uevent = spi_uevent, | |
129 | .suspend = spi_suspend, | |
130 | .resume = spi_resume, | |
131 | }; | |
132 | EXPORT_SYMBOL_GPL(spi_bus_type); | |
133 | ||
b885244e DB |
134 | |
135 | static int spi_drv_probe(struct device *dev) | |
136 | { | |
137 | const struct spi_driver *sdrv = to_spi_driver(dev->driver); | |
138 | ||
139 | return sdrv->probe(to_spi_device(dev)); | |
140 | } | |
141 | ||
142 | static int spi_drv_remove(struct device *dev) | |
143 | { | |
144 | const struct spi_driver *sdrv = to_spi_driver(dev->driver); | |
145 | ||
146 | return sdrv->remove(to_spi_device(dev)); | |
147 | } | |
148 | ||
149 | static void spi_drv_shutdown(struct device *dev) | |
150 | { | |
151 | const struct spi_driver *sdrv = to_spi_driver(dev->driver); | |
152 | ||
153 | sdrv->shutdown(to_spi_device(dev)); | |
154 | } | |
155 | ||
33e34dc6 DB |
156 | /** |
157 | * spi_register_driver - register a SPI driver | |
158 | * @sdrv: the driver to register | |
159 | * Context: can sleep | |
160 | */ | |
b885244e DB |
161 | int spi_register_driver(struct spi_driver *sdrv) |
162 | { | |
163 | sdrv->driver.bus = &spi_bus_type; | |
164 | if (sdrv->probe) | |
165 | sdrv->driver.probe = spi_drv_probe; | |
166 | if (sdrv->remove) | |
167 | sdrv->driver.remove = spi_drv_remove; | |
168 | if (sdrv->shutdown) | |
169 | sdrv->driver.shutdown = spi_drv_shutdown; | |
170 | return driver_register(&sdrv->driver); | |
171 | } | |
172 | EXPORT_SYMBOL_GPL(spi_register_driver); | |
173 | ||
8ae12a0d DB |
174 | /*-------------------------------------------------------------------------*/ |
175 | ||
176 | /* SPI devices should normally not be created by SPI device drivers; that | |
177 | * would make them board-specific. Similarly with SPI master drivers. | |
178 | * Device registration normally goes into like arch/.../mach.../board-YYY.c | |
179 | * with other readonly (flashable) information about mainboard devices. | |
180 | */ | |
181 | ||
182 | struct boardinfo { | |
183 | struct list_head list; | |
184 | unsigned n_board_info; | |
185 | struct spi_board_info board_info[0]; | |
186 | }; | |
187 | ||
188 | static LIST_HEAD(board_list); | |
94040828 | 189 | static DEFINE_MUTEX(board_lock); |
8ae12a0d DB |
190 | |
191 | ||
33e34dc6 DB |
192 | /** |
193 | * spi_new_device - instantiate one new SPI device | |
194 | * @master: Controller to which device is connected | |
195 | * @chip: Describes the SPI device | |
196 | * Context: can sleep | |
197 | * | |
198 | * On typical mainboards, this is purely internal; and it's not needed | |
8ae12a0d DB |
199 | * after board init creates the hard-wired devices. Some development |
200 | * platforms may not be able to use spi_register_board_info though, and | |
201 | * this is exported so that for example a USB or parport based adapter | |
202 | * driver could add devices (which it would learn about out-of-band). | |
082c8cb4 DB |
203 | * |
204 | * Returns the new device, or NULL. | |
8ae12a0d | 205 | */ |
e9d5a461 AB |
206 | struct spi_device *spi_new_device(struct spi_master *master, |
207 | struct spi_board_info *chip) | |
8ae12a0d DB |
208 | { |
209 | struct spi_device *proxy; | |
07b24630 | 210 | struct device *dev = master->cdev.dev; |
8ae12a0d DB |
211 | int status; |
212 | ||
082c8cb4 DB |
213 | /* NOTE: caller did any chip->bus_num checks necessary. |
214 | * | |
215 | * Also, unless we change the return value convention to use | |
216 | * error-or-pointer (not NULL-or-pointer), troubleshootability | |
217 | * suggests syslogged diagnostics are best here (ugh). | |
218 | */ | |
219 | ||
220 | /* Chipselects are numbered 0..max; validate. */ | |
221 | if (chip->chip_select >= master->num_chipselect) { | |
222 | dev_err(dev, "cs%d > max %d\n", | |
223 | chip->chip_select, | |
224 | master->num_chipselect); | |
225 | return NULL; | |
226 | } | |
8ae12a0d | 227 | |
0c868461 | 228 | if (!spi_master_get(master)) |
8ae12a0d DB |
229 | return NULL; |
230 | ||
231 | proxy = kzalloc(sizeof *proxy, GFP_KERNEL); | |
232 | if (!proxy) { | |
233 | dev_err(dev, "can't alloc dev for cs%d\n", | |
234 | chip->chip_select); | |
235 | goto fail; | |
236 | } | |
237 | proxy->master = master; | |
238 | proxy->chip_select = chip->chip_select; | |
239 | proxy->max_speed_hz = chip->max_speed_hz; | |
980a01c9 | 240 | proxy->mode = chip->mode; |
8ae12a0d DB |
241 | proxy->irq = chip->irq; |
242 | proxy->modalias = chip->modalias; | |
243 | ||
244 | snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id, | |
07b24630 | 245 | "%s.%u", master->cdev.class_id, |
8ae12a0d DB |
246 | chip->chip_select); |
247 | proxy->dev.parent = dev; | |
248 | proxy->dev.bus = &spi_bus_type; | |
249 | proxy->dev.platform_data = (void *) chip->platform_data; | |
250 | proxy->controller_data = chip->controller_data; | |
251 | proxy->controller_state = NULL; | |
252 | proxy->dev.release = spidev_release; | |
253 | ||
082c8cb4 | 254 | /* drivers may modify this initial i/o setup */ |
8ae12a0d DB |
255 | status = master->setup(proxy); |
256 | if (status < 0) { | |
082c8cb4 | 257 | dev_err(dev, "can't %s %s, status %d\n", |
8ae12a0d DB |
258 | "setup", proxy->dev.bus_id, status); |
259 | goto fail; | |
260 | } | |
261 | ||
262 | /* driver core catches callers that misbehave by defining | |
263 | * devices that already exist. | |
264 | */ | |
265 | status = device_register(&proxy->dev); | |
266 | if (status < 0) { | |
082c8cb4 | 267 | dev_err(dev, "can't %s %s, status %d\n", |
8ae12a0d | 268 | "add", proxy->dev.bus_id, status); |
b885244e | 269 | goto fail; |
8ae12a0d DB |
270 | } |
271 | dev_dbg(dev, "registered child %s\n", proxy->dev.bus_id); | |
272 | return proxy; | |
b885244e DB |
273 | |
274 | fail: | |
0c868461 | 275 | spi_master_put(master); |
b885244e DB |
276 | kfree(proxy); |
277 | return NULL; | |
8ae12a0d DB |
278 | } |
279 | EXPORT_SYMBOL_GPL(spi_new_device); | |
280 | ||
33e34dc6 DB |
281 | /** |
282 | * spi_register_board_info - register SPI devices for a given board | |
283 | * @info: array of chip descriptors | |
284 | * @n: how many descriptors are provided | |
285 | * Context: can sleep | |
286 | * | |
8ae12a0d DB |
287 | * Board-specific early init code calls this (probably during arch_initcall) |
288 | * with segments of the SPI device table. Any device nodes are created later, | |
289 | * after the relevant parent SPI controller (bus_num) is defined. We keep | |
290 | * this table of devices forever, so that reloading a controller driver will | |
291 | * not make Linux forget about these hard-wired devices. | |
292 | * | |
293 | * Other code can also call this, e.g. a particular add-on board might provide | |
294 | * SPI devices through its expansion connector, so code initializing that board | |
295 | * would naturally declare its SPI devices. | |
296 | * | |
297 | * The board info passed can safely be __initdata ... but be careful of | |
298 | * any embedded pointers (platform_data, etc), they're copied as-is. | |
299 | */ | |
300 | int __init | |
301 | spi_register_board_info(struct spi_board_info const *info, unsigned n) | |
302 | { | |
303 | struct boardinfo *bi; | |
304 | ||
b885244e | 305 | bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL); |
8ae12a0d DB |
306 | if (!bi) |
307 | return -ENOMEM; | |
308 | bi->n_board_info = n; | |
b885244e | 309 | memcpy(bi->board_info, info, n * sizeof *info); |
8ae12a0d | 310 | |
94040828 | 311 | mutex_lock(&board_lock); |
8ae12a0d | 312 | list_add_tail(&bi->list, &board_list); |
94040828 | 313 | mutex_unlock(&board_lock); |
8ae12a0d DB |
314 | return 0; |
315 | } | |
8ae12a0d DB |
316 | |
317 | /* FIXME someone should add support for a __setup("spi", ...) that | |
318 | * creates board info from kernel command lines | |
319 | */ | |
320 | ||
149a6501 | 321 | static void scan_boardinfo(struct spi_master *master) |
8ae12a0d DB |
322 | { |
323 | struct boardinfo *bi; | |
8ae12a0d | 324 | |
94040828 | 325 | mutex_lock(&board_lock); |
8ae12a0d DB |
326 | list_for_each_entry(bi, &board_list, list) { |
327 | struct spi_board_info *chip = bi->board_info; | |
328 | unsigned n; | |
329 | ||
330 | for (n = bi->n_board_info; n > 0; n--, chip++) { | |
331 | if (chip->bus_num != master->bus_num) | |
332 | continue; | |
082c8cb4 DB |
333 | /* NOTE: this relies on spi_new_device to |
334 | * issue diagnostics when given bogus inputs | |
8ae12a0d | 335 | */ |
8ae12a0d DB |
336 | (void) spi_new_device(master, chip); |
337 | } | |
338 | } | |
94040828 | 339 | mutex_unlock(&board_lock); |
8ae12a0d DB |
340 | } |
341 | ||
342 | /*-------------------------------------------------------------------------*/ | |
343 | ||
07b24630 | 344 | static void spi_master_release(struct class_device *cdev) |
8ae12a0d DB |
345 | { |
346 | struct spi_master *master; | |
347 | ||
07b24630 | 348 | master = container_of(cdev, struct spi_master, cdev); |
8ae12a0d DB |
349 | kfree(master); |
350 | } | |
351 | ||
352 | static struct class spi_master_class = { | |
353 | .name = "spi_master", | |
354 | .owner = THIS_MODULE, | |
07b24630 | 355 | .release = spi_master_release, |
8ae12a0d DB |
356 | }; |
357 | ||
358 | ||
359 | /** | |
360 | * spi_alloc_master - allocate SPI master controller | |
361 | * @dev: the controller, possibly using the platform_bus | |
33e34dc6 | 362 | * @size: how much zeroed driver-private data to allocate; the pointer to this |
ba1a0513 | 363 | * memory is in the class_data field of the returned class_device, |
0c868461 | 364 | * accessible with spi_master_get_devdata(). |
33e34dc6 | 365 | * Context: can sleep |
8ae12a0d DB |
366 | * |
367 | * This call is used only by SPI master controller drivers, which are the | |
368 | * only ones directly touching chip registers. It's how they allocate | |
ba1a0513 | 369 | * an spi_master structure, prior to calling spi_register_master(). |
8ae12a0d DB |
370 | * |
371 | * This must be called from context that can sleep. It returns the SPI | |
372 | * master structure on success, else NULL. | |
373 | * | |
374 | * The caller is responsible for assigning the bus number and initializing | |
ba1a0513 | 375 | * the master's methods before calling spi_register_master(); and (after errors |
0c868461 | 376 | * adding the device) calling spi_master_put() to prevent a memory leak. |
8ae12a0d | 377 | */ |
e9d5a461 | 378 | struct spi_master *spi_alloc_master(struct device *dev, unsigned size) |
8ae12a0d DB |
379 | { |
380 | struct spi_master *master; | |
381 | ||
0c868461 DB |
382 | if (!dev) |
383 | return NULL; | |
384 | ||
e94b1766 | 385 | master = kzalloc(size + sizeof *master, GFP_KERNEL); |
8ae12a0d DB |
386 | if (!master) |
387 | return NULL; | |
388 | ||
07b24630 GKH |
389 | class_device_initialize(&master->cdev); |
390 | master->cdev.class = &spi_master_class; | |
391 | master->cdev.dev = get_device(dev); | |
0c868461 | 392 | spi_master_set_devdata(master, &master[1]); |
8ae12a0d DB |
393 | |
394 | return master; | |
395 | } | |
396 | EXPORT_SYMBOL_GPL(spi_alloc_master); | |
397 | ||
398 | /** | |
399 | * spi_register_master - register SPI master controller | |
400 | * @master: initialized master, originally from spi_alloc_master() | |
33e34dc6 | 401 | * Context: can sleep |
8ae12a0d DB |
402 | * |
403 | * SPI master controllers connect to their drivers using some non-SPI bus, | |
404 | * such as the platform bus. The final stage of probe() in that code | |
405 | * includes calling spi_register_master() to hook up to this SPI bus glue. | |
406 | * | |
407 | * SPI controllers use board specific (often SOC specific) bus numbers, | |
408 | * and board-specific addressing for SPI devices combines those numbers | |
409 | * with chip select numbers. Since SPI does not directly support dynamic | |
410 | * device identification, boards need configuration tables telling which | |
411 | * chip is at which address. | |
412 | * | |
413 | * This must be called from context that can sleep. It returns zero on | |
414 | * success, else a negative error code (dropping the master's refcount). | |
0c868461 DB |
415 | * After a successful return, the caller is responsible for calling |
416 | * spi_unregister_master(). | |
8ae12a0d | 417 | */ |
e9d5a461 | 418 | int spi_register_master(struct spi_master *master) |
8ae12a0d | 419 | { |
e44a45ae | 420 | static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1); |
07b24630 | 421 | struct device *dev = master->cdev.dev; |
8ae12a0d DB |
422 | int status = -ENODEV; |
423 | int dynamic = 0; | |
424 | ||
0c868461 DB |
425 | if (!dev) |
426 | return -ENODEV; | |
427 | ||
082c8cb4 DB |
428 | /* even if it's just one always-selected device, there must |
429 | * be at least one chipselect | |
430 | */ | |
431 | if (master->num_chipselect == 0) | |
432 | return -EINVAL; | |
433 | ||
8ae12a0d | 434 | /* convention: dynamically assigned bus IDs count down from the max */ |
a020ed75 | 435 | if (master->bus_num < 0) { |
082c8cb4 DB |
436 | /* FIXME switch to an IDR based scheme, something like |
437 | * I2C now uses, so we can't run out of "dynamic" IDs | |
438 | */ | |
8ae12a0d | 439 | master->bus_num = atomic_dec_return(&dyn_bus_id); |
b885244e | 440 | dynamic = 1; |
8ae12a0d DB |
441 | } |
442 | ||
443 | /* register the device, then userspace will see it. | |
444 | * registration fails if the bus ID is in use. | |
445 | */ | |
07b24630 | 446 | snprintf(master->cdev.class_id, sizeof master->cdev.class_id, |
8ae12a0d | 447 | "spi%u", master->bus_num); |
07b24630 | 448 | status = class_device_add(&master->cdev); |
b885244e | 449 | if (status < 0) |
8ae12a0d | 450 | goto done; |
07b24630 | 451 | dev_dbg(dev, "registered master %s%s\n", master->cdev.class_id, |
8ae12a0d DB |
452 | dynamic ? " (dynamic)" : ""); |
453 | ||
454 | /* populate children from any spi device tables */ | |
455 | scan_boardinfo(master); | |
456 | status = 0; | |
457 | done: | |
458 | return status; | |
459 | } | |
460 | EXPORT_SYMBOL_GPL(spi_register_master); | |
461 | ||
462 | ||
463 | static int __unregister(struct device *dev, void *unused) | |
464 | { | |
465 | /* note: before about 2.6.14-rc1 this would corrupt memory: */ | |
0c868461 | 466 | spi_unregister_device(to_spi_device(dev)); |
8ae12a0d DB |
467 | return 0; |
468 | } | |
469 | ||
470 | /** | |
471 | * spi_unregister_master - unregister SPI master controller | |
472 | * @master: the master being unregistered | |
33e34dc6 | 473 | * Context: can sleep |
8ae12a0d DB |
474 | * |
475 | * This call is used only by SPI master controller drivers, which are the | |
476 | * only ones directly touching chip registers. | |
477 | * | |
478 | * This must be called from context that can sleep. | |
479 | */ | |
480 | void spi_unregister_master(struct spi_master *master) | |
481 | { | |
89fc9a1a JG |
482 | int dummy; |
483 | ||
07b24630 GKH |
484 | dummy = device_for_each_child(master->cdev.dev, NULL, __unregister); |
485 | class_device_unregister(&master->cdev); | |
8ae12a0d DB |
486 | } |
487 | EXPORT_SYMBOL_GPL(spi_unregister_master); | |
488 | ||
489 | /** | |
490 | * spi_busnum_to_master - look up master associated with bus_num | |
491 | * @bus_num: the master's bus number | |
33e34dc6 | 492 | * Context: can sleep |
8ae12a0d DB |
493 | * |
494 | * This call may be used with devices that are registered after | |
495 | * arch init time. It returns a refcounted pointer to the relevant | |
496 | * spi_master (which the caller must release), or NULL if there is | |
497 | * no such master registered. | |
498 | */ | |
499 | struct spi_master *spi_busnum_to_master(u16 bus_num) | |
500 | { | |
1e9a51dc AN |
501 | struct class_device *cdev; |
502 | struct spi_master *master = NULL; | |
503 | struct spi_master *m; | |
504 | ||
505 | down(&spi_master_class.sem); | |
506 | list_for_each_entry(cdev, &spi_master_class.children, node) { | |
07b24630 | 507 | m = container_of(cdev, struct spi_master, cdev); |
1e9a51dc AN |
508 | if (m->bus_num == bus_num) { |
509 | master = spi_master_get(m); | |
510 | break; | |
511 | } | |
512 | } | |
513 | up(&spi_master_class.sem); | |
514 | return master; | |
8ae12a0d DB |
515 | } |
516 | EXPORT_SYMBOL_GPL(spi_busnum_to_master); | |
517 | ||
518 | ||
519 | /*-------------------------------------------------------------------------*/ | |
520 | ||
5d870c8e AM |
521 | static void spi_complete(void *arg) |
522 | { | |
523 | complete(arg); | |
524 | } | |
525 | ||
8ae12a0d DB |
526 | /** |
527 | * spi_sync - blocking/synchronous SPI data transfers | |
528 | * @spi: device with which data will be exchanged | |
529 | * @message: describes the data transfers | |
33e34dc6 | 530 | * Context: can sleep |
8ae12a0d DB |
531 | * |
532 | * This call may only be used from a context that may sleep. The sleep | |
533 | * is non-interruptible, and has no timeout. Low-overhead controller | |
534 | * drivers may DMA directly into and out of the message buffers. | |
535 | * | |
536 | * Note that the SPI device's chip select is active during the message, | |
537 | * and then is normally disabled between messages. Drivers for some | |
538 | * frequently-used devices may want to minimize costs of selecting a chip, | |
539 | * by leaving it selected in anticipation that the next message will go | |
540 | * to the same chip. (That may increase power usage.) | |
541 | * | |
0c868461 DB |
542 | * Also, the caller is guaranteeing that the memory associated with the |
543 | * message will not be freed before this call returns. | |
544 | * | |
8ae12a0d DB |
545 | * The return value is a negative error code if the message could not be |
546 | * submitted, else zero. When the value is zero, then message->status is | |
33e34dc6 | 547 | * also defined; it's the completion code for the transfer, either zero |
8ae12a0d DB |
548 | * or a negative error code from the controller driver. |
549 | */ | |
550 | int spi_sync(struct spi_device *spi, struct spi_message *message) | |
551 | { | |
60be6b9a | 552 | DECLARE_COMPLETION_ONSTACK(done); |
8ae12a0d DB |
553 | int status; |
554 | ||
5d870c8e | 555 | message->complete = spi_complete; |
8ae12a0d DB |
556 | message->context = &done; |
557 | status = spi_async(spi, message); | |
558 | if (status == 0) | |
559 | wait_for_completion(&done); | |
560 | message->context = NULL; | |
561 | return status; | |
562 | } | |
563 | EXPORT_SYMBOL_GPL(spi_sync); | |
564 | ||
a9948b61 DB |
565 | /* portable code must never pass more than 32 bytes */ |
566 | #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES) | |
8ae12a0d DB |
567 | |
568 | static u8 *buf; | |
569 | ||
570 | /** | |
571 | * spi_write_then_read - SPI synchronous write followed by read | |
572 | * @spi: device with which data will be exchanged | |
573 | * @txbuf: data to be written (need not be dma-safe) | |
574 | * @n_tx: size of txbuf, in bytes | |
575 | * @rxbuf: buffer into which data will be read | |
576 | * @n_rx: size of rxbuf, in bytes (need not be dma-safe) | |
33e34dc6 | 577 | * Context: can sleep |
8ae12a0d DB |
578 | * |
579 | * This performs a half duplex MicroWire style transaction with the | |
580 | * device, sending txbuf and then reading rxbuf. The return value | |
581 | * is zero for success, else a negative errno status code. | |
b885244e | 582 | * This call may only be used from a context that may sleep. |
8ae12a0d | 583 | * |
0c868461 | 584 | * Parameters to this routine are always copied using a small buffer; |
33e34dc6 DB |
585 | * portable code should never use this for more than 32 bytes. |
586 | * Performance-sensitive or bulk transfer code should instead use | |
0c868461 | 587 | * spi_{async,sync}() calls with dma-safe buffers. |
8ae12a0d DB |
588 | */ |
589 | int spi_write_then_read(struct spi_device *spi, | |
590 | const u8 *txbuf, unsigned n_tx, | |
591 | u8 *rxbuf, unsigned n_rx) | |
592 | { | |
593 | static DECLARE_MUTEX(lock); | |
594 | ||
595 | int status; | |
596 | struct spi_message message; | |
597 | struct spi_transfer x[2]; | |
598 | u8 *local_buf; | |
599 | ||
600 | /* Use preallocated DMA-safe buffer. We can't avoid copying here, | |
601 | * (as a pure convenience thing), but we can keep heap costs | |
602 | * out of the hot path ... | |
603 | */ | |
604 | if ((n_tx + n_rx) > SPI_BUFSIZ) | |
605 | return -EINVAL; | |
606 | ||
8275c642 VW |
607 | spi_message_init(&message); |
608 | memset(x, 0, sizeof x); | |
609 | if (n_tx) { | |
610 | x[0].len = n_tx; | |
611 | spi_message_add_tail(&x[0], &message); | |
612 | } | |
613 | if (n_rx) { | |
614 | x[1].len = n_rx; | |
615 | spi_message_add_tail(&x[1], &message); | |
616 | } | |
617 | ||
8ae12a0d DB |
618 | /* ... unless someone else is using the pre-allocated buffer */ |
619 | if (down_trylock(&lock)) { | |
620 | local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); | |
621 | if (!local_buf) | |
622 | return -ENOMEM; | |
623 | } else | |
624 | local_buf = buf; | |
625 | ||
8ae12a0d DB |
626 | memcpy(local_buf, txbuf, n_tx); |
627 | x[0].tx_buf = local_buf; | |
8ae12a0d | 628 | x[1].rx_buf = local_buf + n_tx; |
8ae12a0d DB |
629 | |
630 | /* do the i/o */ | |
8ae12a0d DB |
631 | status = spi_sync(spi, &message); |
632 | if (status == 0) { | |
633 | memcpy(rxbuf, x[1].rx_buf, n_rx); | |
634 | status = message.status; | |
635 | } | |
636 | ||
637 | if (x[0].tx_buf == buf) | |
638 | up(&lock); | |
639 | else | |
640 | kfree(local_buf); | |
641 | ||
642 | return status; | |
643 | } | |
644 | EXPORT_SYMBOL_GPL(spi_write_then_read); | |
645 | ||
646 | /*-------------------------------------------------------------------------*/ | |
647 | ||
648 | static int __init spi_init(void) | |
649 | { | |
b885244e DB |
650 | int status; |
651 | ||
e94b1766 | 652 | buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); |
b885244e DB |
653 | if (!buf) { |
654 | status = -ENOMEM; | |
655 | goto err0; | |
656 | } | |
657 | ||
658 | status = bus_register(&spi_bus_type); | |
659 | if (status < 0) | |
660 | goto err1; | |
8ae12a0d | 661 | |
b885244e DB |
662 | status = class_register(&spi_master_class); |
663 | if (status < 0) | |
664 | goto err2; | |
8ae12a0d | 665 | return 0; |
b885244e DB |
666 | |
667 | err2: | |
668 | bus_unregister(&spi_bus_type); | |
669 | err1: | |
670 | kfree(buf); | |
671 | buf = NULL; | |
672 | err0: | |
673 | return status; | |
8ae12a0d | 674 | } |
b885244e | 675 | |
8ae12a0d DB |
676 | /* board_info is normally registered in arch_initcall(), |
677 | * but even essential drivers wait till later | |
b885244e DB |
678 | * |
679 | * REVISIT only boardinfo really needs static linking. the rest (device and | |
680 | * driver registration) _could_ be dynamically linked (modular) ... costs | |
681 | * include needing to have boardinfo data structures be much more public. | |
8ae12a0d DB |
682 | */ |
683 | subsys_initcall(spi_init); | |
684 |