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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 | ||
29 | /* SPI bustype and spi_master class are registered during early boot, | |
30 | * usually before board init code provides the SPI device tables, and | |
31 | * are available later when driver init code needs them. | |
32 | * | |
33 | * Drivers for SPI devices started out like those for platform bus | |
34 | * devices. But both have changed in 2.6.15; maybe this should get | |
35 | * an "spi_driver" structure at some point (not currently needed) | |
36 | */ | |
37 | static void spidev_release(struct device *dev) | |
38 | { | |
39 | const struct spi_device *spi = to_spi_device(dev); | |
40 | ||
41 | /* spi masters may cleanup for released devices */ | |
42 | if (spi->master->cleanup) | |
43 | spi->master->cleanup(spi); | |
44 | ||
45 | class_device_put(&spi->master->cdev); | |
46 | kfree(dev); | |
47 | } | |
48 | ||
49 | static ssize_t | |
50 | modalias_show(struct device *dev, struct device_attribute *a, char *buf) | |
51 | { | |
52 | const struct spi_device *spi = to_spi_device(dev); | |
53 | ||
54 | return snprintf(buf, BUS_ID_SIZE + 1, "%s\n", spi->modalias); | |
55 | } | |
56 | ||
57 | static struct device_attribute spi_dev_attrs[] = { | |
58 | __ATTR_RO(modalias), | |
59 | __ATTR_NULL, | |
60 | }; | |
61 | ||
62 | /* modalias support makes "modprobe $MODALIAS" new-style hotplug work, | |
63 | * and the sysfs version makes coldplug work too. | |
64 | */ | |
65 | ||
66 | static int spi_match_device(struct device *dev, struct device_driver *drv) | |
67 | { | |
68 | const struct spi_device *spi = to_spi_device(dev); | |
69 | ||
70 | return strncmp(spi->modalias, drv->name, BUS_ID_SIZE) == 0; | |
71 | } | |
72 | ||
73 | static int spi_uevent(struct device *dev, char **envp, int num_envp, | |
74 | char *buffer, int buffer_size) | |
75 | { | |
76 | const struct spi_device *spi = to_spi_device(dev); | |
77 | ||
78 | envp[0] = buffer; | |
79 | snprintf(buffer, buffer_size, "MODALIAS=%s", spi->modalias); | |
80 | envp[1] = NULL; | |
81 | return 0; | |
82 | } | |
83 | ||
84 | #ifdef CONFIG_PM | |
85 | ||
86 | /* Suspend/resume in "struct device_driver" don't really need that | |
87 | * strange third parameter, so we just make it a constant and expect | |
88 | * SPI drivers to ignore it just like most platform drivers do. | |
89 | * | |
90 | * NOTE: the suspend() method for an spi_master controller driver | |
91 | * should verify that all its child devices are marked as suspended; | |
92 | * suspend requests delivered through sysfs power/state files don't | |
93 | * enforce such constraints. | |
94 | */ | |
95 | static int spi_suspend(struct device *dev, pm_message_t message) | |
96 | { | |
97 | int value; | |
98 | ||
99 | if (!dev->driver || !dev->driver->suspend) | |
100 | return 0; | |
101 | ||
102 | /* suspend will stop irqs and dma; no more i/o */ | |
103 | value = dev->driver->suspend(dev, message); | |
104 | if (value == 0) | |
105 | dev->power.power_state = message; | |
106 | return value; | |
107 | } | |
108 | ||
109 | static int spi_resume(struct device *dev) | |
110 | { | |
111 | int value; | |
112 | ||
113 | if (!dev->driver || !dev->driver->resume) | |
114 | return 0; | |
115 | ||
116 | /* resume may restart the i/o queue */ | |
117 | value = dev->driver->resume(dev); | |
118 | if (value == 0) | |
119 | dev->power.power_state = PMSG_ON; | |
120 | return value; | |
121 | } | |
122 | ||
123 | #else | |
124 | #define spi_suspend NULL | |
125 | #define spi_resume NULL | |
126 | #endif | |
127 | ||
128 | struct bus_type spi_bus_type = { | |
129 | .name = "spi", | |
130 | .dev_attrs = spi_dev_attrs, | |
131 | .match = spi_match_device, | |
132 | .uevent = spi_uevent, | |
133 | .suspend = spi_suspend, | |
134 | .resume = spi_resume, | |
135 | }; | |
136 | EXPORT_SYMBOL_GPL(spi_bus_type); | |
137 | ||
138 | /*-------------------------------------------------------------------------*/ | |
139 | ||
140 | /* SPI devices should normally not be created by SPI device drivers; that | |
141 | * would make them board-specific. Similarly with SPI master drivers. | |
142 | * Device registration normally goes into like arch/.../mach.../board-YYY.c | |
143 | * with other readonly (flashable) information about mainboard devices. | |
144 | */ | |
145 | ||
146 | struct boardinfo { | |
147 | struct list_head list; | |
148 | unsigned n_board_info; | |
149 | struct spi_board_info board_info[0]; | |
150 | }; | |
151 | ||
152 | static LIST_HEAD(board_list); | |
153 | static DECLARE_MUTEX(board_lock); | |
154 | ||
155 | ||
156 | /* On typical mainboards, this is purely internal; and it's not needed | |
157 | * after board init creates the hard-wired devices. Some development | |
158 | * platforms may not be able to use spi_register_board_info though, and | |
159 | * this is exported so that for example a USB or parport based adapter | |
160 | * driver could add devices (which it would learn about out-of-band). | |
161 | */ | |
162 | struct spi_device *__init_or_module | |
163 | spi_new_device(struct spi_master *master, struct spi_board_info *chip) | |
164 | { | |
165 | struct spi_device *proxy; | |
166 | struct device *dev = master->cdev.dev; | |
167 | int status; | |
168 | ||
169 | /* NOTE: caller did any chip->bus_num checks necessary */ | |
170 | ||
171 | if (!class_device_get(&master->cdev)) | |
172 | return NULL; | |
173 | ||
174 | proxy = kzalloc(sizeof *proxy, GFP_KERNEL); | |
175 | if (!proxy) { | |
176 | dev_err(dev, "can't alloc dev for cs%d\n", | |
177 | chip->chip_select); | |
178 | goto fail; | |
179 | } | |
180 | proxy->master = master; | |
181 | proxy->chip_select = chip->chip_select; | |
182 | proxy->max_speed_hz = chip->max_speed_hz; | |
183 | proxy->irq = chip->irq; | |
184 | proxy->modalias = chip->modalias; | |
185 | ||
186 | snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id, | |
187 | "%s.%u", master->cdev.class_id, | |
188 | chip->chip_select); | |
189 | proxy->dev.parent = dev; | |
190 | proxy->dev.bus = &spi_bus_type; | |
191 | proxy->dev.platform_data = (void *) chip->platform_data; | |
192 | proxy->controller_data = chip->controller_data; | |
193 | proxy->controller_state = NULL; | |
194 | proxy->dev.release = spidev_release; | |
195 | ||
196 | /* drivers may modify this default i/o setup */ | |
197 | status = master->setup(proxy); | |
198 | if (status < 0) { | |
199 | dev_dbg(dev, "can't %s %s, status %d\n", | |
200 | "setup", proxy->dev.bus_id, status); | |
201 | goto fail; | |
202 | } | |
203 | ||
204 | /* driver core catches callers that misbehave by defining | |
205 | * devices that already exist. | |
206 | */ | |
207 | status = device_register(&proxy->dev); | |
208 | if (status < 0) { | |
209 | dev_dbg(dev, "can't %s %s, status %d\n", | |
210 | "add", proxy->dev.bus_id, status); | |
211 | fail: | |
212 | class_device_put(&master->cdev); | |
213 | kfree(proxy); | |
214 | return NULL; | |
215 | } | |
216 | dev_dbg(dev, "registered child %s\n", proxy->dev.bus_id); | |
217 | return proxy; | |
218 | } | |
219 | EXPORT_SYMBOL_GPL(spi_new_device); | |
220 | ||
221 | /* | |
222 | * Board-specific early init code calls this (probably during arch_initcall) | |
223 | * with segments of the SPI device table. Any device nodes are created later, | |
224 | * after the relevant parent SPI controller (bus_num) is defined. We keep | |
225 | * this table of devices forever, so that reloading a controller driver will | |
226 | * not make Linux forget about these hard-wired devices. | |
227 | * | |
228 | * Other code can also call this, e.g. a particular add-on board might provide | |
229 | * SPI devices through its expansion connector, so code initializing that board | |
230 | * would naturally declare its SPI devices. | |
231 | * | |
232 | * The board info passed can safely be __initdata ... but be careful of | |
233 | * any embedded pointers (platform_data, etc), they're copied as-is. | |
234 | */ | |
235 | int __init | |
236 | spi_register_board_info(struct spi_board_info const *info, unsigned n) | |
237 | { | |
238 | struct boardinfo *bi; | |
239 | ||
240 | bi = kmalloc (sizeof (*bi) + n * sizeof (*info), GFP_KERNEL); | |
241 | if (!bi) | |
242 | return -ENOMEM; | |
243 | bi->n_board_info = n; | |
244 | memcpy(bi->board_info, info, n * sizeof (*info)); | |
245 | ||
246 | down(&board_lock); | |
247 | list_add_tail(&bi->list, &board_list); | |
248 | up(&board_lock); | |
249 | return 0; | |
250 | } | |
251 | EXPORT_SYMBOL_GPL(spi_register_board_info); | |
252 | ||
253 | /* FIXME someone should add support for a __setup("spi", ...) that | |
254 | * creates board info from kernel command lines | |
255 | */ | |
256 | ||
257 | static void __init_or_module | |
258 | scan_boardinfo(struct spi_master *master) | |
259 | { | |
260 | struct boardinfo *bi; | |
261 | struct device *dev = master->cdev.dev; | |
262 | ||
263 | down(&board_lock); | |
264 | list_for_each_entry(bi, &board_list, list) { | |
265 | struct spi_board_info *chip = bi->board_info; | |
266 | unsigned n; | |
267 | ||
268 | for (n = bi->n_board_info; n > 0; n--, chip++) { | |
269 | if (chip->bus_num != master->bus_num) | |
270 | continue; | |
271 | /* some controllers only have one chip, so they | |
272 | * might not use chipselects. otherwise, the | |
273 | * chipselects are numbered 0..max. | |
274 | */ | |
275 | if (chip->chip_select >= master->num_chipselect | |
276 | && master->num_chipselect) { | |
277 | dev_dbg(dev, "cs%d > max %d\n", | |
278 | chip->chip_select, | |
279 | master->num_chipselect); | |
280 | continue; | |
281 | } | |
282 | (void) spi_new_device(master, chip); | |
283 | } | |
284 | } | |
285 | up(&board_lock); | |
286 | } | |
287 | ||
288 | /*-------------------------------------------------------------------------*/ | |
289 | ||
290 | static void spi_master_release(struct class_device *cdev) | |
291 | { | |
292 | struct spi_master *master; | |
293 | ||
294 | master = container_of(cdev, struct spi_master, cdev); | |
295 | put_device(master->cdev.dev); | |
296 | master->cdev.dev = NULL; | |
297 | kfree(master); | |
298 | } | |
299 | ||
300 | static struct class spi_master_class = { | |
301 | .name = "spi_master", | |
302 | .owner = THIS_MODULE, | |
303 | .release = spi_master_release, | |
304 | }; | |
305 | ||
306 | ||
307 | /** | |
308 | * spi_alloc_master - allocate SPI master controller | |
309 | * @dev: the controller, possibly using the platform_bus | |
310 | * @size: how much driver-private data to preallocate; a pointer to this | |
311 | * memory in the class_data field of the returned class_device | |
312 | * | |
313 | * This call is used only by SPI master controller drivers, which are the | |
314 | * only ones directly touching chip registers. It's how they allocate | |
315 | * an spi_master structure, prior to calling spi_add_master(). | |
316 | * | |
317 | * This must be called from context that can sleep. It returns the SPI | |
318 | * master structure on success, else NULL. | |
319 | * | |
320 | * The caller is responsible for assigning the bus number and initializing | |
321 | * the master's methods before calling spi_add_master(), or else (on error) | |
322 | * calling class_device_put() to prevent a memory leak. | |
323 | */ | |
324 | struct spi_master * __init_or_module | |
325 | spi_alloc_master(struct device *dev, unsigned size) | |
326 | { | |
327 | struct spi_master *master; | |
328 | ||
329 | master = kzalloc(size + sizeof *master, SLAB_KERNEL); | |
330 | if (!master) | |
331 | return NULL; | |
332 | ||
333 | master->cdev.class = &spi_master_class; | |
334 | master->cdev.dev = get_device(dev); | |
335 | class_set_devdata(&master->cdev, &master[1]); | |
336 | ||
337 | return master; | |
338 | } | |
339 | EXPORT_SYMBOL_GPL(spi_alloc_master); | |
340 | ||
341 | /** | |
342 | * spi_register_master - register SPI master controller | |
343 | * @master: initialized master, originally from spi_alloc_master() | |
344 | * | |
345 | * SPI master controllers connect to their drivers using some non-SPI bus, | |
346 | * such as the platform bus. The final stage of probe() in that code | |
347 | * includes calling spi_register_master() to hook up to this SPI bus glue. | |
348 | * | |
349 | * SPI controllers use board specific (often SOC specific) bus numbers, | |
350 | * and board-specific addressing for SPI devices combines those numbers | |
351 | * with chip select numbers. Since SPI does not directly support dynamic | |
352 | * device identification, boards need configuration tables telling which | |
353 | * chip is at which address. | |
354 | * | |
355 | * This must be called from context that can sleep. It returns zero on | |
356 | * success, else a negative error code (dropping the master's refcount). | |
357 | */ | |
358 | int __init_or_module | |
359 | spi_register_master(struct spi_master *master) | |
360 | { | |
361 | static atomic_t dyn_bus_id = ATOMIC_INIT(0); | |
362 | struct device *dev = master->cdev.dev; | |
363 | int status = -ENODEV; | |
364 | int dynamic = 0; | |
365 | ||
366 | /* convention: dynamically assigned bus IDs count down from the max */ | |
367 | if (master->bus_num == 0) { | |
368 | master->bus_num = atomic_dec_return(&dyn_bus_id); | |
369 | dynamic = 0; | |
370 | } | |
371 | ||
372 | /* register the device, then userspace will see it. | |
373 | * registration fails if the bus ID is in use. | |
374 | */ | |
375 | snprintf(master->cdev.class_id, sizeof master->cdev.class_id, | |
376 | "spi%u", master->bus_num); | |
377 | status = class_device_register(&master->cdev); | |
378 | if (status < 0) { | |
379 | class_device_put(&master->cdev); | |
380 | goto done; | |
381 | } | |
382 | dev_dbg(dev, "registered master %s%s\n", master->cdev.class_id, | |
383 | dynamic ? " (dynamic)" : ""); | |
384 | ||
385 | /* populate children from any spi device tables */ | |
386 | scan_boardinfo(master); | |
387 | status = 0; | |
388 | done: | |
389 | return status; | |
390 | } | |
391 | EXPORT_SYMBOL_GPL(spi_register_master); | |
392 | ||
393 | ||
394 | static int __unregister(struct device *dev, void *unused) | |
395 | { | |
396 | /* note: before about 2.6.14-rc1 this would corrupt memory: */ | |
397 | device_unregister(dev); | |
398 | return 0; | |
399 | } | |
400 | ||
401 | /** | |
402 | * spi_unregister_master - unregister SPI master controller | |
403 | * @master: the master being unregistered | |
404 | * | |
405 | * This call is used only by SPI master controller drivers, which are the | |
406 | * only ones directly touching chip registers. | |
407 | * | |
408 | * This must be called from context that can sleep. | |
409 | */ | |
410 | void spi_unregister_master(struct spi_master *master) | |
411 | { | |
412 | class_device_unregister(&master->cdev); | |
413 | (void) device_for_each_child(master->cdev.dev, NULL, __unregister); | |
414 | } | |
415 | EXPORT_SYMBOL_GPL(spi_unregister_master); | |
416 | ||
417 | /** | |
418 | * spi_busnum_to_master - look up master associated with bus_num | |
419 | * @bus_num: the master's bus number | |
420 | * | |
421 | * This call may be used with devices that are registered after | |
422 | * arch init time. It returns a refcounted pointer to the relevant | |
423 | * spi_master (which the caller must release), or NULL if there is | |
424 | * no such master registered. | |
425 | */ | |
426 | struct spi_master *spi_busnum_to_master(u16 bus_num) | |
427 | { | |
428 | if (bus_num) { | |
429 | char name[8]; | |
430 | struct kobject *bus; | |
431 | ||
432 | snprintf(name, sizeof name, "spi%u", bus_num); | |
433 | bus = kset_find_obj(&spi_master_class.subsys.kset, name); | |
434 | if (bus) | |
435 | return container_of(bus, struct spi_master, cdev.kobj); | |
436 | } | |
437 | return NULL; | |
438 | } | |
439 | EXPORT_SYMBOL_GPL(spi_busnum_to_master); | |
440 | ||
441 | ||
442 | /*-------------------------------------------------------------------------*/ | |
443 | ||
444 | /** | |
445 | * spi_sync - blocking/synchronous SPI data transfers | |
446 | * @spi: device with which data will be exchanged | |
447 | * @message: describes the data transfers | |
448 | * | |
449 | * This call may only be used from a context that may sleep. The sleep | |
450 | * is non-interruptible, and has no timeout. Low-overhead controller | |
451 | * drivers may DMA directly into and out of the message buffers. | |
452 | * | |
453 | * Note that the SPI device's chip select is active during the message, | |
454 | * and then is normally disabled between messages. Drivers for some | |
455 | * frequently-used devices may want to minimize costs of selecting a chip, | |
456 | * by leaving it selected in anticipation that the next message will go | |
457 | * to the same chip. (That may increase power usage.) | |
458 | * | |
459 | * The return value is a negative error code if the message could not be | |
460 | * submitted, else zero. When the value is zero, then message->status is | |
461 | * also defined: it's the completion code for the transfer, either zero | |
462 | * or a negative error code from the controller driver. | |
463 | */ | |
464 | int spi_sync(struct spi_device *spi, struct spi_message *message) | |
465 | { | |
466 | DECLARE_COMPLETION(done); | |
467 | int status; | |
468 | ||
469 | message->complete = (void (*)(void *)) complete; | |
470 | message->context = &done; | |
471 | status = spi_async(spi, message); | |
472 | if (status == 0) | |
473 | wait_for_completion(&done); | |
474 | message->context = NULL; | |
475 | return status; | |
476 | } | |
477 | EXPORT_SYMBOL_GPL(spi_sync); | |
478 | ||
479 | #define SPI_BUFSIZ (SMP_CACHE_BYTES) | |
480 | ||
481 | static u8 *buf; | |
482 | ||
483 | /** | |
484 | * spi_write_then_read - SPI synchronous write followed by read | |
485 | * @spi: device with which data will be exchanged | |
486 | * @txbuf: data to be written (need not be dma-safe) | |
487 | * @n_tx: size of txbuf, in bytes | |
488 | * @rxbuf: buffer into which data will be read | |
489 | * @n_rx: size of rxbuf, in bytes (need not be dma-safe) | |
490 | * | |
491 | * This performs a half duplex MicroWire style transaction with the | |
492 | * device, sending txbuf and then reading rxbuf. The return value | |
493 | * is zero for success, else a negative errno status code. | |
494 | * | |
495 | * Parameters to this routine are always copied using a small buffer, | |
496 | * large transfers should use use spi_{async,sync}() calls with | |
497 | * dma-safe buffers. | |
498 | */ | |
499 | int spi_write_then_read(struct spi_device *spi, | |
500 | const u8 *txbuf, unsigned n_tx, | |
501 | u8 *rxbuf, unsigned n_rx) | |
502 | { | |
503 | static DECLARE_MUTEX(lock); | |
504 | ||
505 | int status; | |
506 | struct spi_message message; | |
507 | struct spi_transfer x[2]; | |
508 | u8 *local_buf; | |
509 | ||
510 | /* Use preallocated DMA-safe buffer. We can't avoid copying here, | |
511 | * (as a pure convenience thing), but we can keep heap costs | |
512 | * out of the hot path ... | |
513 | */ | |
514 | if ((n_tx + n_rx) > SPI_BUFSIZ) | |
515 | return -EINVAL; | |
516 | ||
517 | /* ... unless someone else is using the pre-allocated buffer */ | |
518 | if (down_trylock(&lock)) { | |
519 | local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL); | |
520 | if (!local_buf) | |
521 | return -ENOMEM; | |
522 | } else | |
523 | local_buf = buf; | |
524 | ||
525 | memset(x, 0, sizeof x); | |
526 | ||
527 | memcpy(local_buf, txbuf, n_tx); | |
528 | x[0].tx_buf = local_buf; | |
529 | x[0].len = n_tx; | |
530 | ||
531 | x[1].rx_buf = local_buf + n_tx; | |
532 | x[1].len = n_rx; | |
533 | ||
534 | /* do the i/o */ | |
535 | message.transfers = x; | |
536 | message.n_transfer = ARRAY_SIZE(x); | |
537 | status = spi_sync(spi, &message); | |
538 | if (status == 0) { | |
539 | memcpy(rxbuf, x[1].rx_buf, n_rx); | |
540 | status = message.status; | |
541 | } | |
542 | ||
543 | if (x[0].tx_buf == buf) | |
544 | up(&lock); | |
545 | else | |
546 | kfree(local_buf); | |
547 | ||
548 | return status; | |
549 | } | |
550 | EXPORT_SYMBOL_GPL(spi_write_then_read); | |
551 | ||
552 | /*-------------------------------------------------------------------------*/ | |
553 | ||
554 | static int __init spi_init(void) | |
555 | { | |
556 | buf = kmalloc(SPI_BUFSIZ, SLAB_KERNEL); | |
557 | if (!buf) | |
558 | return -ENOMEM; | |
559 | ||
560 | bus_register(&spi_bus_type); | |
561 | class_register(&spi_master_class); | |
562 | return 0; | |
563 | } | |
564 | /* board_info is normally registered in arch_initcall(), | |
565 | * but even essential drivers wait till later | |
566 | */ | |
567 | subsys_initcall(spi_init); | |
568 |