ia64/linux-2.6.18-xen.hg

view drivers/spi/spi.c @ 893:f994bfe9b93b

linux/blktap2: reduce TLB flush scope

c/s 885 added very coarse TLB flushing. Since these flushes always
follow single page updates, single page flushes (when available) are
sufficient.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
author Keir Fraser <keir.fraser@citrix.com>
date Thu Jun 04 10:32:57 2009 +0100 (2009-06-04)
parents 831230e53067
children
line source
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 */
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>
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".
32 */
33 static void spidev_release(struct device *dev)
34 {
35 const struct spi_device *spi = to_spi_device(dev);
37 /* spi masters may cleanup for released devices */
38 if (spi->master->cleanup)
39 spi->master->cleanup(spi);
41 spi_master_put(spi->master);
42 kfree(dev);
43 }
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);
50 return snprintf(buf, BUS_ID_SIZE + 1, "%s\n", spi->modalias);
51 }
53 static struct device_attribute spi_dev_attrs[] = {
54 __ATTR_RO(modalias),
55 __ATTR_NULL,
56 };
58 /* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
59 * and the sysfs version makes coldplug work too.
60 */
62 static int spi_match_device(struct device *dev, struct device_driver *drv)
63 {
64 const struct spi_device *spi = to_spi_device(dev);
66 return strncmp(spi->modalias, drv->name, BUS_ID_SIZE) == 0;
67 }
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);
74 envp[0] = buffer;
75 snprintf(buffer, buffer_size, "MODALIAS=%s", spi->modalias);
76 envp[1] = NULL;
77 return 0;
78 }
80 #ifdef CONFIG_PM
82 /*
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 {
90 int value;
91 struct spi_driver *drv = to_spi_driver(dev->driver);
93 if (!drv || !drv->suspend)
94 return 0;
96 /* suspend will stop irqs and dma; no more i/o */
97 value = drv->suspend(to_spi_device(dev), message);
98 if (value == 0)
99 dev->power.power_state = message;
100 return value;
101 }
103 static int spi_resume(struct device *dev)
104 {
105 int value;
106 struct spi_driver *drv = to_spi_driver(dev->driver);
108 if (!drv || !drv->resume)
109 return 0;
111 /* resume may restart the i/o queue */
112 value = drv->resume(to_spi_device(dev));
113 if (value == 0)
114 dev->power.power_state = PMSG_ON;
115 return value;
116 }
118 #else
119 #define spi_suspend NULL
120 #define spi_resume NULL
121 #endif
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);
134 static int spi_drv_probe(struct device *dev)
135 {
136 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
138 return sdrv->probe(to_spi_device(dev));
139 }
141 static int spi_drv_remove(struct device *dev)
142 {
143 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
145 return sdrv->remove(to_spi_device(dev));
146 }
148 static void spi_drv_shutdown(struct device *dev)
149 {
150 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
152 sdrv->shutdown(to_spi_device(dev));
153 }
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);
168 /*-------------------------------------------------------------------------*/
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 */
176 struct boardinfo {
177 struct list_head list;
178 unsigned n_board_info;
179 struct spi_board_info board_info[0];
180 };
182 static LIST_HEAD(board_list);
183 static DECLARE_MUTEX(board_lock);
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;
196 struct device *dev = master->cdev.dev;
197 int status;
199 /* NOTE: caller did any chip->bus_num checks necessary */
201 if (!spi_master_get(master))
202 return NULL;
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;
213 proxy->mode = chip->mode;
214 proxy->irq = chip->irq;
215 proxy->modalias = chip->modalias;
217 snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id,
218 "%s.%u", master->cdev.class_id,
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;
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 }
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);
242 goto fail;
243 }
244 dev_dbg(dev, "registered child %s\n", proxy->dev.bus_id);
245 return proxy;
247 fail:
248 spi_master_put(master);
249 kfree(proxy);
250 return NULL;
251 }
252 EXPORT_SYMBOL_GPL(spi_new_device);
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;
273 bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL);
274 if (!bi)
275 return -ENOMEM;
276 bi->n_board_info = n;
277 memcpy(bi->board_info, info, n * sizeof *info);
279 down(&board_lock);
280 list_add_tail(&bi->list, &board_list);
281 up(&board_lock);
282 return 0;
283 }
284 EXPORT_SYMBOL_GPL(spi_register_board_info);
286 /* FIXME someone should add support for a __setup("spi", ...) that
287 * creates board info from kernel command lines
288 */
290 static void __init_or_module
291 scan_boardinfo(struct spi_master *master)
292 {
293 struct boardinfo *bi;
294 struct device *dev = master->cdev.dev;
296 down(&board_lock);
297 list_for_each_entry(bi, &board_list, list) {
298 struct spi_board_info *chip = bi->board_info;
299 unsigned n;
301 for (n = bi->n_board_info; n > 0; n--, chip++) {
302 if (chip->bus_num != master->bus_num)
303 continue;
304 /* some controllers only have one chip, so they
305 * might not use chipselects. otherwise, the
306 * chipselects are numbered 0..max.
307 */
308 if (chip->chip_select >= master->num_chipselect
309 && master->num_chipselect) {
310 dev_dbg(dev, "cs%d > max %d\n",
311 chip->chip_select,
312 master->num_chipselect);
313 continue;
314 }
315 (void) spi_new_device(master, chip);
316 }
317 }
318 up(&board_lock);
319 }
321 /*-------------------------------------------------------------------------*/
323 static void spi_master_release(struct class_device *cdev)
324 {
325 struct spi_master *master;
327 master = container_of(cdev, struct spi_master, cdev);
328 kfree(master);
329 }
331 static struct class spi_master_class = {
332 .name = "spi_master",
333 .owner = THIS_MODULE,
334 .release = spi_master_release,
335 };
338 /**
339 * spi_alloc_master - allocate SPI master controller
340 * @dev: the controller, possibly using the platform_bus
341 * @size: how much driver-private data to preallocate; the pointer to this
342 * memory is in the class_data field of the returned class_device,
343 * accessible with spi_master_get_devdata().
344 *
345 * This call is used only by SPI master controller drivers, which are the
346 * only ones directly touching chip registers. It's how they allocate
347 * an spi_master structure, prior to calling spi_register_master().
348 *
349 * This must be called from context that can sleep. It returns the SPI
350 * master structure on success, else NULL.
351 *
352 * The caller is responsible for assigning the bus number and initializing
353 * the master's methods before calling spi_register_master(); and (after errors
354 * adding the device) calling spi_master_put() to prevent a memory leak.
355 */
356 struct spi_master * __init_or_module
357 spi_alloc_master(struct device *dev, unsigned size)
358 {
359 struct spi_master *master;
361 if (!dev)
362 return NULL;
364 master = kzalloc(size + sizeof *master, SLAB_KERNEL);
365 if (!master)
366 return NULL;
368 class_device_initialize(&master->cdev);
369 master->cdev.class = &spi_master_class;
370 master->cdev.dev = get_device(dev);
371 spi_master_set_devdata(master, &master[1]);
373 return master;
374 }
375 EXPORT_SYMBOL_GPL(spi_alloc_master);
377 /**
378 * spi_register_master - register SPI master controller
379 * @master: initialized master, originally from spi_alloc_master()
380 *
381 * SPI master controllers connect to their drivers using some non-SPI bus,
382 * such as the platform bus. The final stage of probe() in that code
383 * includes calling spi_register_master() to hook up to this SPI bus glue.
384 *
385 * SPI controllers use board specific (often SOC specific) bus numbers,
386 * and board-specific addressing for SPI devices combines those numbers
387 * with chip select numbers. Since SPI does not directly support dynamic
388 * device identification, boards need configuration tables telling which
389 * chip is at which address.
390 *
391 * This must be called from context that can sleep. It returns zero on
392 * success, else a negative error code (dropping the master's refcount).
393 * After a successful return, the caller is responsible for calling
394 * spi_unregister_master().
395 */
396 int __init_or_module
397 spi_register_master(struct spi_master *master)
398 {
399 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<16) - 1);
400 struct device *dev = master->cdev.dev;
401 int status = -ENODEV;
402 int dynamic = 0;
404 if (!dev)
405 return -ENODEV;
407 /* convention: dynamically assigned bus IDs count down from the max */
408 if (master->bus_num < 0) {
409 master->bus_num = atomic_dec_return(&dyn_bus_id);
410 dynamic = 1;
411 }
413 /* register the device, then userspace will see it.
414 * registration fails if the bus ID is in use.
415 */
416 snprintf(master->cdev.class_id, sizeof master->cdev.class_id,
417 "spi%u", master->bus_num);
418 status = class_device_add(&master->cdev);
419 if (status < 0)
420 goto done;
421 dev_dbg(dev, "registered master %s%s\n", master->cdev.class_id,
422 dynamic ? " (dynamic)" : "");
424 /* populate children from any spi device tables */
425 scan_boardinfo(master);
426 status = 0;
427 done:
428 return status;
429 }
430 EXPORT_SYMBOL_GPL(spi_register_master);
433 static int __unregister(struct device *dev, void *unused)
434 {
435 /* note: before about 2.6.14-rc1 this would corrupt memory: */
436 spi_unregister_device(to_spi_device(dev));
437 return 0;
438 }
440 /**
441 * spi_unregister_master - unregister SPI master controller
442 * @master: the master being unregistered
443 *
444 * This call is used only by SPI master controller drivers, which are the
445 * only ones directly touching chip registers.
446 *
447 * This must be called from context that can sleep.
448 */
449 void spi_unregister_master(struct spi_master *master)
450 {
451 (void) device_for_each_child(master->cdev.dev, NULL, __unregister);
452 class_device_unregister(&master->cdev);
453 }
454 EXPORT_SYMBOL_GPL(spi_unregister_master);
456 /**
457 * spi_busnum_to_master - look up master associated with bus_num
458 * @bus_num: the master's bus number
459 *
460 * This call may be used with devices that are registered after
461 * arch init time. It returns a refcounted pointer to the relevant
462 * spi_master (which the caller must release), or NULL if there is
463 * no such master registered.
464 */
465 struct spi_master *spi_busnum_to_master(u16 bus_num)
466 {
467 if (bus_num) {
468 char name[8];
469 struct kobject *bus;
471 snprintf(name, sizeof name, "spi%u", bus_num);
472 bus = kset_find_obj(&spi_master_class.subsys.kset, name);
473 if (bus)
474 return container_of(bus, struct spi_master, cdev.kobj);
475 }
476 return NULL;
477 }
478 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
481 /*-------------------------------------------------------------------------*/
483 static void spi_complete(void *arg)
484 {
485 complete(arg);
486 }
488 /**
489 * spi_sync - blocking/synchronous SPI data transfers
490 * @spi: device with which data will be exchanged
491 * @message: describes the data transfers
492 *
493 * This call may only be used from a context that may sleep. The sleep
494 * is non-interruptible, and has no timeout. Low-overhead controller
495 * drivers may DMA directly into and out of the message buffers.
496 *
497 * Note that the SPI device's chip select is active during the message,
498 * and then is normally disabled between messages. Drivers for some
499 * frequently-used devices may want to minimize costs of selecting a chip,
500 * by leaving it selected in anticipation that the next message will go
501 * to the same chip. (That may increase power usage.)
502 *
503 * Also, the caller is guaranteeing that the memory associated with the
504 * message will not be freed before this call returns.
505 *
506 * The return value is a negative error code if the message could not be
507 * submitted, else zero. When the value is zero, then message->status is
508 * also defined: it's the completion code for the transfer, either zero
509 * or a negative error code from the controller driver.
510 */
511 int spi_sync(struct spi_device *spi, struct spi_message *message)
512 {
513 DECLARE_COMPLETION_ONSTACK(done);
514 int status;
516 message->complete = spi_complete;
517 message->context = &done;
518 status = spi_async(spi, message);
519 if (status == 0)
520 wait_for_completion(&done);
521 message->context = NULL;
522 return status;
523 }
524 EXPORT_SYMBOL_GPL(spi_sync);
526 /* portable code must never pass more than 32 bytes */
527 #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
529 static u8 *buf;
531 /**
532 * spi_write_then_read - SPI synchronous write followed by read
533 * @spi: device with which data will be exchanged
534 * @txbuf: data to be written (need not be dma-safe)
535 * @n_tx: size of txbuf, in bytes
536 * @rxbuf: buffer into which data will be read
537 * @n_rx: size of rxbuf, in bytes (need not be dma-safe)
538 *
539 * This performs a half duplex MicroWire style transaction with the
540 * device, sending txbuf and then reading rxbuf. The return value
541 * is zero for success, else a negative errno status code.
542 * This call may only be used from a context that may sleep.
543 *
544 * Parameters to this routine are always copied using a small buffer;
545 * performance-sensitive or bulk transfer code should instead use
546 * spi_{async,sync}() calls with dma-safe buffers.
547 */
548 int spi_write_then_read(struct spi_device *spi,
549 const u8 *txbuf, unsigned n_tx,
550 u8 *rxbuf, unsigned n_rx)
551 {
552 static DECLARE_MUTEX(lock);
554 int status;
555 struct spi_message message;
556 struct spi_transfer x[2];
557 u8 *local_buf;
559 /* Use preallocated DMA-safe buffer. We can't avoid copying here,
560 * (as a pure convenience thing), but we can keep heap costs
561 * out of the hot path ...
562 */
563 if ((n_tx + n_rx) > SPI_BUFSIZ)
564 return -EINVAL;
566 spi_message_init(&message);
567 memset(x, 0, sizeof x);
568 if (n_tx) {
569 x[0].len = n_tx;
570 spi_message_add_tail(&x[0], &message);
571 }
572 if (n_rx) {
573 x[1].len = n_rx;
574 spi_message_add_tail(&x[1], &message);
575 }
577 /* ... unless someone else is using the pre-allocated buffer */
578 if (down_trylock(&lock)) {
579 local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
580 if (!local_buf)
581 return -ENOMEM;
582 } else
583 local_buf = buf;
585 memcpy(local_buf, txbuf, n_tx);
586 x[0].tx_buf = local_buf;
587 x[1].rx_buf = local_buf + n_tx;
589 /* do the i/o */
590 status = spi_sync(spi, &message);
591 if (status == 0) {
592 memcpy(rxbuf, x[1].rx_buf, n_rx);
593 status = message.status;
594 }
596 if (x[0].tx_buf == buf)
597 up(&lock);
598 else
599 kfree(local_buf);
601 return status;
602 }
603 EXPORT_SYMBOL_GPL(spi_write_then_read);
605 /*-------------------------------------------------------------------------*/
607 static int __init spi_init(void)
608 {
609 int status;
611 buf = kmalloc(SPI_BUFSIZ, SLAB_KERNEL);
612 if (!buf) {
613 status = -ENOMEM;
614 goto err0;
615 }
617 status = bus_register(&spi_bus_type);
618 if (status < 0)
619 goto err1;
621 status = class_register(&spi_master_class);
622 if (status < 0)
623 goto err2;
624 return 0;
626 err2:
627 bus_unregister(&spi_bus_type);
628 err1:
629 kfree(buf);
630 buf = NULL;
631 err0:
632 return status;
633 }
635 /* board_info is normally registered in arch_initcall(),
636 * but even essential drivers wait till later
637 *
638 * REVISIT only boardinfo really needs static linking. the rest (device and
639 * driver registration) _could_ be dynamically linked (modular) ... costs
640 * include needing to have boardinfo data structures be much more public.
641 */
642 subsys_initcall(spi_init);