blob: b31f4431849b25e771d301f956b3afd31b00d2bf [file] [log] [blame]
David Brownell8ae12a02006-01-08 13:34:19 -08001/*
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>
Matthias Kaehlcke94040822007-07-17 04:04:16 -070026#include <linux/mutex.h>
David Brownell8ae12a02006-01-08 13:34:19 -080027#include <linux/spi/spi.h>
28
29
David Brownellb8852442006-01-08 13:34:23 -080030/* 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".
David Brownell8ae12a02006-01-08 13:34:19 -080033 */
34static void spidev_release(struct device *dev)
35{
Hans-Peter Nilsson0ffa0282007-02-12 00:52:45 -080036 struct spi_device *spi = to_spi_device(dev);
David Brownell8ae12a02006-01-08 13:34:19 -080037
38 /* spi masters may cleanup for released devices */
39 if (spi->master->cleanup)
40 spi->master->cleanup(spi);
41
David Brownell0c868462006-01-08 13:34:25 -080042 spi_master_put(spi->master);
David Brownell8ae12a02006-01-08 13:34:19 -080043 kfree(dev);
44}
45
46static ssize_t
47modalias_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
54static 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
63static 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
Kay Sievers7eff2e72007-08-14 15:15:12 +020070static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
David Brownell8ae12a02006-01-08 13:34:19 -080071{
72 const struct spi_device *spi = to_spi_device(dev);
73
Kay Sievers7eff2e72007-08-14 15:15:12 +020074 add_uevent_var(env, "MODALIAS=%s", spi->modalias);
David Brownell8ae12a02006-01-08 13:34:19 -080075 return 0;
76}
77
78#ifdef CONFIG_PM
79
David Brownellb8852442006-01-08 13:34:23 -080080/*
David Brownell8ae12a02006-01-08 13:34:19 -080081 * NOTE: the suspend() method for an spi_master controller driver
82 * should verify that all its child devices are marked as suspended;
83 * suspend requests delivered through sysfs power/state files don't
84 * enforce such constraints.
85 */
86static int spi_suspend(struct device *dev, pm_message_t message)
87{
David Brownellb8852442006-01-08 13:34:23 -080088 int value;
89 struct spi_driver *drv = to_spi_driver(dev->driver);
David Brownell8ae12a02006-01-08 13:34:19 -080090
Stephen Streetd2799f02006-02-20 18:27:56 -080091 if (!drv || !drv->suspend)
David Brownell8ae12a02006-01-08 13:34:19 -080092 return 0;
93
94 /* suspend will stop irqs and dma; no more i/o */
David Brownellb8852442006-01-08 13:34:23 -080095 value = drv->suspend(to_spi_device(dev), message);
David Brownell8ae12a02006-01-08 13:34:19 -080096 if (value == 0)
97 dev->power.power_state = message;
98 return value;
99}
100
101static int spi_resume(struct device *dev)
102{
David Brownellb8852442006-01-08 13:34:23 -0800103 int value;
104 struct spi_driver *drv = to_spi_driver(dev->driver);
David Brownell8ae12a02006-01-08 13:34:19 -0800105
Stephen Streetd2799f02006-02-20 18:27:56 -0800106 if (!drv || !drv->resume)
David Brownell8ae12a02006-01-08 13:34:19 -0800107 return 0;
108
109 /* resume may restart the i/o queue */
David Brownellb8852442006-01-08 13:34:23 -0800110 value = drv->resume(to_spi_device(dev));
David Brownell8ae12a02006-01-08 13:34:19 -0800111 if (value == 0)
112 dev->power.power_state = PMSG_ON;
113 return value;
114}
115
116#else
117#define spi_suspend NULL
118#define spi_resume NULL
119#endif
120
121struct bus_type spi_bus_type = {
122 .name = "spi",
123 .dev_attrs = spi_dev_attrs,
124 .match = spi_match_device,
125 .uevent = spi_uevent,
126 .suspend = spi_suspend,
127 .resume = spi_resume,
128};
129EXPORT_SYMBOL_GPL(spi_bus_type);
130
David Brownellb8852442006-01-08 13:34:23 -0800131
132static int spi_drv_probe(struct device *dev)
133{
134 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
135
136 return sdrv->probe(to_spi_device(dev));
137}
138
139static int spi_drv_remove(struct device *dev)
140{
141 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
142
143 return sdrv->remove(to_spi_device(dev));
144}
145
146static void spi_drv_shutdown(struct device *dev)
147{
148 const struct spi_driver *sdrv = to_spi_driver(dev->driver);
149
150 sdrv->shutdown(to_spi_device(dev));
151}
152
David Brownell33e34dc2007-05-08 00:32:21 -0700153/**
154 * spi_register_driver - register a SPI driver
155 * @sdrv: the driver to register
156 * Context: can sleep
157 */
David Brownellb8852442006-01-08 13:34:23 -0800158int spi_register_driver(struct spi_driver *sdrv)
159{
160 sdrv->driver.bus = &spi_bus_type;
161 if (sdrv->probe)
162 sdrv->driver.probe = spi_drv_probe;
163 if (sdrv->remove)
164 sdrv->driver.remove = spi_drv_remove;
165 if (sdrv->shutdown)
166 sdrv->driver.shutdown = spi_drv_shutdown;
167 return driver_register(&sdrv->driver);
168}
169EXPORT_SYMBOL_GPL(spi_register_driver);
170
David Brownell8ae12a02006-01-08 13:34:19 -0800171/*-------------------------------------------------------------------------*/
172
173/* SPI devices should normally not be created by SPI device drivers; that
174 * would make them board-specific. Similarly with SPI master drivers.
175 * Device registration normally goes into like arch/.../mach.../board-YYY.c
176 * with other readonly (flashable) information about mainboard devices.
177 */
178
179struct boardinfo {
180 struct list_head list;
181 unsigned n_board_info;
182 struct spi_board_info board_info[0];
183};
184
185static LIST_HEAD(board_list);
Matthias Kaehlcke94040822007-07-17 04:04:16 -0700186static DEFINE_MUTEX(board_lock);
David Brownell8ae12a02006-01-08 13:34:19 -0800187
188
David Brownell33e34dc2007-05-08 00:32:21 -0700189/**
190 * spi_new_device - instantiate one new SPI device
191 * @master: Controller to which device is connected
192 * @chip: Describes the SPI device
193 * Context: can sleep
194 *
195 * On typical mainboards, this is purely internal; and it's not needed
David Brownell8ae12a02006-01-08 13:34:19 -0800196 * after board init creates the hard-wired devices. Some development
197 * platforms may not be able to use spi_register_board_info though, and
198 * this is exported so that for example a USB or parport based adapter
199 * driver could add devices (which it would learn about out-of-band).
David Brownell082c8cb2007-07-31 00:39:45 -0700200 *
201 * Returns the new device, or NULL.
David Brownell8ae12a02006-01-08 13:34:19 -0800202 */
Adrian Bunke9d5a462007-03-26 21:32:23 -0800203struct spi_device *spi_new_device(struct spi_master *master,
204 struct spi_board_info *chip)
David Brownell8ae12a02006-01-08 13:34:19 -0800205{
206 struct spi_device *proxy;
Tony Jones49dce682007-10-16 01:27:48 -0700207 struct device *dev = master->dev.parent;
David Brownell8ae12a02006-01-08 13:34:19 -0800208 int status;
209
David Brownell082c8cb2007-07-31 00:39:45 -0700210 /* NOTE: caller did any chip->bus_num checks necessary.
211 *
212 * Also, unless we change the return value convention to use
213 * error-or-pointer (not NULL-or-pointer), troubleshootability
214 * suggests syslogged diagnostics are best here (ugh).
215 */
216
217 /* Chipselects are numbered 0..max; validate. */
218 if (chip->chip_select >= master->num_chipselect) {
219 dev_err(dev, "cs%d > max %d\n",
220 chip->chip_select,
221 master->num_chipselect);
222 return NULL;
223 }
David Brownell8ae12a02006-01-08 13:34:19 -0800224
David Brownell0c868462006-01-08 13:34:25 -0800225 if (!spi_master_get(master))
David Brownell8ae12a02006-01-08 13:34:19 -0800226 return NULL;
227
228 proxy = kzalloc(sizeof *proxy, GFP_KERNEL);
229 if (!proxy) {
230 dev_err(dev, "can't alloc dev for cs%d\n",
231 chip->chip_select);
232 goto fail;
233 }
234 proxy->master = master;
235 proxy->chip_select = chip->chip_select;
236 proxy->max_speed_hz = chip->max_speed_hz;
David Brownell980a01c2006-06-28 07:47:15 -0700237 proxy->mode = chip->mode;
David Brownell8ae12a02006-01-08 13:34:19 -0800238 proxy->irq = chip->irq;
239 proxy->modalias = chip->modalias;
240
241 snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id,
Tony Jones49dce682007-10-16 01:27:48 -0700242 "%s.%u", master->dev.bus_id,
David Brownell8ae12a02006-01-08 13:34:19 -0800243 chip->chip_select);
244 proxy->dev.parent = dev;
245 proxy->dev.bus = &spi_bus_type;
246 proxy->dev.platform_data = (void *) chip->platform_data;
247 proxy->controller_data = chip->controller_data;
248 proxy->controller_state = NULL;
249 proxy->dev.release = spidev_release;
250
David Brownell082c8cb2007-07-31 00:39:45 -0700251 /* drivers may modify this initial i/o setup */
David Brownell8ae12a02006-01-08 13:34:19 -0800252 status = master->setup(proxy);
253 if (status < 0) {
David Brownell082c8cb2007-07-31 00:39:45 -0700254 dev_err(dev, "can't %s %s, status %d\n",
David Brownell8ae12a02006-01-08 13:34:19 -0800255 "setup", proxy->dev.bus_id, status);
256 goto fail;
257 }
258
259 /* driver core catches callers that misbehave by defining
260 * devices that already exist.
261 */
262 status = device_register(&proxy->dev);
263 if (status < 0) {
David Brownell082c8cb2007-07-31 00:39:45 -0700264 dev_err(dev, "can't %s %s, status %d\n",
David Brownell8ae12a02006-01-08 13:34:19 -0800265 "add", proxy->dev.bus_id, status);
David Brownellb8852442006-01-08 13:34:23 -0800266 goto fail;
David Brownell8ae12a02006-01-08 13:34:19 -0800267 }
268 dev_dbg(dev, "registered child %s\n", proxy->dev.bus_id);
269 return proxy;
David Brownellb8852442006-01-08 13:34:23 -0800270
271fail:
David Brownell0c868462006-01-08 13:34:25 -0800272 spi_master_put(master);
David Brownellb8852442006-01-08 13:34:23 -0800273 kfree(proxy);
274 return NULL;
David Brownell8ae12a02006-01-08 13:34:19 -0800275}
276EXPORT_SYMBOL_GPL(spi_new_device);
277
David Brownell33e34dc2007-05-08 00:32:21 -0700278/**
279 * spi_register_board_info - register SPI devices for a given board
280 * @info: array of chip descriptors
281 * @n: how many descriptors are provided
282 * Context: can sleep
283 *
David Brownell8ae12a02006-01-08 13:34:19 -0800284 * Board-specific early init code calls this (probably during arch_initcall)
285 * with segments of the SPI device table. Any device nodes are created later,
286 * after the relevant parent SPI controller (bus_num) is defined. We keep
287 * this table of devices forever, so that reloading a controller driver will
288 * not make Linux forget about these hard-wired devices.
289 *
290 * Other code can also call this, e.g. a particular add-on board might provide
291 * SPI devices through its expansion connector, so code initializing that board
292 * would naturally declare its SPI devices.
293 *
294 * The board info passed can safely be __initdata ... but be careful of
295 * any embedded pointers (platform_data, etc), they're copied as-is.
296 */
297int __init
298spi_register_board_info(struct spi_board_info const *info, unsigned n)
299{
300 struct boardinfo *bi;
301
David Brownellb8852442006-01-08 13:34:23 -0800302 bi = kmalloc(sizeof(*bi) + n * sizeof *info, GFP_KERNEL);
David Brownell8ae12a02006-01-08 13:34:19 -0800303 if (!bi)
304 return -ENOMEM;
305 bi->n_board_info = n;
David Brownellb8852442006-01-08 13:34:23 -0800306 memcpy(bi->board_info, info, n * sizeof *info);
David Brownell8ae12a02006-01-08 13:34:19 -0800307
Matthias Kaehlcke94040822007-07-17 04:04:16 -0700308 mutex_lock(&board_lock);
David Brownell8ae12a02006-01-08 13:34:19 -0800309 list_add_tail(&bi->list, &board_list);
Matthias Kaehlcke94040822007-07-17 04:04:16 -0700310 mutex_unlock(&board_lock);
David Brownell8ae12a02006-01-08 13:34:19 -0800311 return 0;
312}
David Brownell8ae12a02006-01-08 13:34:19 -0800313
314/* FIXME someone should add support for a __setup("spi", ...) that
315 * creates board info from kernel command lines
316 */
317
Adrian Bunk149a6502007-07-21 04:37:52 -0700318static void scan_boardinfo(struct spi_master *master)
David Brownell8ae12a02006-01-08 13:34:19 -0800319{
320 struct boardinfo *bi;
David Brownell8ae12a02006-01-08 13:34:19 -0800321
Matthias Kaehlcke94040822007-07-17 04:04:16 -0700322 mutex_lock(&board_lock);
David Brownell8ae12a02006-01-08 13:34:19 -0800323 list_for_each_entry(bi, &board_list, list) {
324 struct spi_board_info *chip = bi->board_info;
325 unsigned n;
326
327 for (n = bi->n_board_info; n > 0; n--, chip++) {
328 if (chip->bus_num != master->bus_num)
329 continue;
David Brownell082c8cb2007-07-31 00:39:45 -0700330 /* NOTE: this relies on spi_new_device to
331 * issue diagnostics when given bogus inputs
David Brownell8ae12a02006-01-08 13:34:19 -0800332 */
David Brownell8ae12a02006-01-08 13:34:19 -0800333 (void) spi_new_device(master, chip);
334 }
335 }
Matthias Kaehlcke94040822007-07-17 04:04:16 -0700336 mutex_unlock(&board_lock);
David Brownell8ae12a02006-01-08 13:34:19 -0800337}
338
339/*-------------------------------------------------------------------------*/
340
Tony Jones49dce682007-10-16 01:27:48 -0700341static void spi_master_release(struct device *dev)
David Brownell8ae12a02006-01-08 13:34:19 -0800342{
343 struct spi_master *master;
344
Tony Jones49dce682007-10-16 01:27:48 -0700345 master = container_of(dev, struct spi_master, dev);
David Brownell8ae12a02006-01-08 13:34:19 -0800346 kfree(master);
347}
348
349static struct class spi_master_class = {
350 .name = "spi_master",
351 .owner = THIS_MODULE,
Tony Jones49dce682007-10-16 01:27:48 -0700352 .dev_release = spi_master_release,
David Brownell8ae12a02006-01-08 13:34:19 -0800353};
354
355
356/**
357 * spi_alloc_master - allocate SPI master controller
358 * @dev: the controller, possibly using the platform_bus
David Brownell33e34dc2007-05-08 00:32:21 -0700359 * @size: how much zeroed driver-private data to allocate; the pointer to this
Tony Jones49dce682007-10-16 01:27:48 -0700360 * memory is in the driver_data field of the returned device,
David Brownell0c868462006-01-08 13:34:25 -0800361 * accessible with spi_master_get_devdata().
David Brownell33e34dc2007-05-08 00:32:21 -0700362 * Context: can sleep
David Brownell8ae12a02006-01-08 13:34:19 -0800363 *
364 * This call is used only by SPI master controller drivers, which are the
365 * only ones directly touching chip registers. It's how they allocate
dmitry pervushinba1a0512006-05-20 15:00:14 -0700366 * an spi_master structure, prior to calling spi_register_master().
David Brownell8ae12a02006-01-08 13:34:19 -0800367 *
368 * This must be called from context that can sleep. It returns the SPI
369 * master structure on success, else NULL.
370 *
371 * The caller is responsible for assigning the bus number and initializing
dmitry pervushinba1a0512006-05-20 15:00:14 -0700372 * the master's methods before calling spi_register_master(); and (after errors
David Brownell0c868462006-01-08 13:34:25 -0800373 * adding the device) calling spi_master_put() to prevent a memory leak.
David Brownell8ae12a02006-01-08 13:34:19 -0800374 */
Adrian Bunke9d5a462007-03-26 21:32:23 -0800375struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
David Brownell8ae12a02006-01-08 13:34:19 -0800376{
377 struct spi_master *master;
378
David Brownell0c868462006-01-08 13:34:25 -0800379 if (!dev)
380 return NULL;
381
Christoph Lametere94b1762006-12-06 20:33:17 -0800382 master = kzalloc(size + sizeof *master, GFP_KERNEL);
David Brownell8ae12a02006-01-08 13:34:19 -0800383 if (!master)
384 return NULL;
385
Tony Jones49dce682007-10-16 01:27:48 -0700386 device_initialize(&master->dev);
387 master->dev.class = &spi_master_class;
388 master->dev.parent = get_device(dev);
David Brownell0c868462006-01-08 13:34:25 -0800389 spi_master_set_devdata(master, &master[1]);
David Brownell8ae12a02006-01-08 13:34:19 -0800390
391 return master;
392}
393EXPORT_SYMBOL_GPL(spi_alloc_master);
394
395/**
396 * spi_register_master - register SPI master controller
397 * @master: initialized master, originally from spi_alloc_master()
David Brownell33e34dc2007-05-08 00:32:21 -0700398 * Context: can sleep
David Brownell8ae12a02006-01-08 13:34:19 -0800399 *
400 * SPI master controllers connect to their drivers using some non-SPI bus,
401 * such as the platform bus. The final stage of probe() in that code
402 * includes calling spi_register_master() to hook up to this SPI bus glue.
403 *
404 * SPI controllers use board specific (often SOC specific) bus numbers,
405 * and board-specific addressing for SPI devices combines those numbers
406 * with chip select numbers. Since SPI does not directly support dynamic
407 * device identification, boards need configuration tables telling which
408 * chip is at which address.
409 *
410 * This must be called from context that can sleep. It returns zero on
411 * success, else a negative error code (dropping the master's refcount).
David Brownell0c868462006-01-08 13:34:25 -0800412 * After a successful return, the caller is responsible for calling
413 * spi_unregister_master().
David Brownell8ae12a02006-01-08 13:34:19 -0800414 */
Adrian Bunke9d5a462007-03-26 21:32:23 -0800415int spi_register_master(struct spi_master *master)
David Brownell8ae12a02006-01-08 13:34:19 -0800416{
David Brownelle44a45a2007-06-03 13:50:40 -0700417 static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
Tony Jones49dce682007-10-16 01:27:48 -0700418 struct device *dev = master->dev.parent;
David Brownell8ae12a02006-01-08 13:34:19 -0800419 int status = -ENODEV;
420 int dynamic = 0;
421
David Brownell0c868462006-01-08 13:34:25 -0800422 if (!dev)
423 return -ENODEV;
424
David Brownell082c8cb2007-07-31 00:39:45 -0700425 /* even if it's just one always-selected device, there must
426 * be at least one chipselect
427 */
428 if (master->num_chipselect == 0)
429 return -EINVAL;
430
David Brownell8ae12a02006-01-08 13:34:19 -0800431 /* convention: dynamically assigned bus IDs count down from the max */
David Brownella020ed72006-04-03 15:49:04 -0700432 if (master->bus_num < 0) {
David Brownell082c8cb2007-07-31 00:39:45 -0700433 /* FIXME switch to an IDR based scheme, something like
434 * I2C now uses, so we can't run out of "dynamic" IDs
435 */
David Brownell8ae12a02006-01-08 13:34:19 -0800436 master->bus_num = atomic_dec_return(&dyn_bus_id);
David Brownellb8852442006-01-08 13:34:23 -0800437 dynamic = 1;
David Brownell8ae12a02006-01-08 13:34:19 -0800438 }
439
440 /* register the device, then userspace will see it.
441 * registration fails if the bus ID is in use.
442 */
Tony Jones49dce682007-10-16 01:27:48 -0700443 snprintf(master->dev.bus_id, sizeof master->dev.bus_id,
David Brownell8ae12a02006-01-08 13:34:19 -0800444 "spi%u", master->bus_num);
Tony Jones49dce682007-10-16 01:27:48 -0700445 status = device_add(&master->dev);
David Brownellb8852442006-01-08 13:34:23 -0800446 if (status < 0)
David Brownell8ae12a02006-01-08 13:34:19 -0800447 goto done;
Tony Jones49dce682007-10-16 01:27:48 -0700448 dev_dbg(dev, "registered master %s%s\n", master->dev.bus_id,
David Brownell8ae12a02006-01-08 13:34:19 -0800449 dynamic ? " (dynamic)" : "");
450
451 /* populate children from any spi device tables */
452 scan_boardinfo(master);
453 status = 0;
454done:
455 return status;
456}
457EXPORT_SYMBOL_GPL(spi_register_master);
458
459
Atsushi Nemoto350d0072007-11-14 16:59:22 -0800460static int __unregister(struct device *dev, void *master_dev)
David Brownell8ae12a02006-01-08 13:34:19 -0800461{
462 /* note: before about 2.6.14-rc1 this would corrupt memory: */
Atsushi Nemoto350d0072007-11-14 16:59:22 -0800463 if (dev != master_dev)
464 spi_unregister_device(to_spi_device(dev));
David Brownell8ae12a02006-01-08 13:34:19 -0800465 return 0;
466}
467
468/**
469 * spi_unregister_master - unregister SPI master controller
470 * @master: the master being unregistered
David Brownell33e34dc2007-05-08 00:32:21 -0700471 * Context: can sleep
David Brownell8ae12a02006-01-08 13:34:19 -0800472 *
473 * This call is used only by SPI master controller drivers, which are the
474 * only ones directly touching chip registers.
475 *
476 * This must be called from context that can sleep.
477 */
478void spi_unregister_master(struct spi_master *master)
479{
Jeff Garzik89fc9a12006-12-06 20:35:35 -0800480 int dummy;
481
Atsushi Nemoto350d0072007-11-14 16:59:22 -0800482 dummy = device_for_each_child(master->dev.parent, &master->dev,
483 __unregister);
Tony Jones49dce682007-10-16 01:27:48 -0700484 device_unregister(&master->dev);
David Brownell8ae12a02006-01-08 13:34:19 -0800485}
486EXPORT_SYMBOL_GPL(spi_unregister_master);
487
488/**
489 * spi_busnum_to_master - look up master associated with bus_num
490 * @bus_num: the master's bus number
David Brownell33e34dc2007-05-08 00:32:21 -0700491 * Context: can sleep
David Brownell8ae12a02006-01-08 13:34:19 -0800492 *
493 * This call may be used with devices that are registered after
494 * arch init time. It returns a refcounted pointer to the relevant
495 * spi_master (which the caller must release), or NULL if there is
496 * no such master registered.
497 */
498struct spi_master *spi_busnum_to_master(u16 bus_num)
499{
Tony Jones49dce682007-10-16 01:27:48 -0700500 struct device *dev;
Atsushi Nemoto1e9a51d2007-01-26 00:56:54 -0800501 struct spi_master *master = NULL;
502 struct spi_master *m;
David Brownell8ae12a02006-01-08 13:34:19 -0800503
Atsushi Nemoto1e9a51d2007-01-26 00:56:54 -0800504 down(&spi_master_class.sem);
Tony Jones49dce682007-10-16 01:27:48 -0700505 list_for_each_entry(dev, &spi_master_class.children, node) {
506 m = container_of(dev, struct spi_master, dev);
Atsushi Nemoto1e9a51d2007-01-26 00:56:54 -0800507 if (m->bus_num == bus_num) {
508 master = spi_master_get(m);
509 break;
510 }
511 }
512 up(&spi_master_class.sem);
513 return master;
David Brownell8ae12a02006-01-08 13:34:19 -0800514}
515EXPORT_SYMBOL_GPL(spi_busnum_to_master);
516
517
518/*-------------------------------------------------------------------------*/
519
Andrew Morton5d870c82006-01-11 11:23:49 -0800520static void spi_complete(void *arg)
521{
522 complete(arg);
523}
524
David Brownell8ae12a02006-01-08 13:34:19 -0800525/**
526 * spi_sync - blocking/synchronous SPI data transfers
527 * @spi: device with which data will be exchanged
528 * @message: describes the data transfers
David Brownell33e34dc2007-05-08 00:32:21 -0700529 * Context: can sleep
David Brownell8ae12a02006-01-08 13:34:19 -0800530 *
531 * This call may only be used from a context that may sleep. The sleep
532 * is non-interruptible, and has no timeout. Low-overhead controller
533 * drivers may DMA directly into and out of the message buffers.
534 *
535 * Note that the SPI device's chip select is active during the message,
536 * and then is normally disabled between messages. Drivers for some
537 * frequently-used devices may want to minimize costs of selecting a chip,
538 * by leaving it selected in anticipation that the next message will go
539 * to the same chip. (That may increase power usage.)
540 *
David Brownell0c868462006-01-08 13:34:25 -0800541 * Also, the caller is guaranteeing that the memory associated with the
542 * message will not be freed before this call returns.
543 *
David Brownell8ae12a02006-01-08 13:34:19 -0800544 * The return value is a negative error code if the message could not be
545 * submitted, else zero. When the value is zero, then message->status is
David Brownell33e34dc2007-05-08 00:32:21 -0700546 * also defined; it's the completion code for the transfer, either zero
David Brownell8ae12a02006-01-08 13:34:19 -0800547 * or a negative error code from the controller driver.
548 */
549int spi_sync(struct spi_device *spi, struct spi_message *message)
550{
Ingo Molnar60be6b92006-07-03 00:25:26 -0700551 DECLARE_COMPLETION_ONSTACK(done);
David Brownell8ae12a02006-01-08 13:34:19 -0800552 int status;
553
Andrew Morton5d870c82006-01-11 11:23:49 -0800554 message->complete = spi_complete;
David Brownell8ae12a02006-01-08 13:34:19 -0800555 message->context = &done;
556 status = spi_async(spi, message);
557 if (status == 0)
558 wait_for_completion(&done);
559 message->context = NULL;
560 return status;
561}
562EXPORT_SYMBOL_GPL(spi_sync);
563
David Brownella9948b62006-04-02 10:37:40 -0800564/* portable code must never pass more than 32 bytes */
565#define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
David Brownell8ae12a02006-01-08 13:34:19 -0800566
567static u8 *buf;
568
569/**
570 * spi_write_then_read - SPI synchronous write followed by read
571 * @spi: device with which data will be exchanged
572 * @txbuf: data to be written (need not be dma-safe)
573 * @n_tx: size of txbuf, in bytes
574 * @rxbuf: buffer into which data will be read
575 * @n_rx: size of rxbuf, in bytes (need not be dma-safe)
David Brownell33e34dc2007-05-08 00:32:21 -0700576 * Context: can sleep
David Brownell8ae12a02006-01-08 13:34:19 -0800577 *
578 * This performs a half duplex MicroWire style transaction with the
579 * device, sending txbuf and then reading rxbuf. The return value
580 * is zero for success, else a negative errno status code.
David Brownellb8852442006-01-08 13:34:23 -0800581 * This call may only be used from a context that may sleep.
David Brownell8ae12a02006-01-08 13:34:19 -0800582 *
David Brownell0c868462006-01-08 13:34:25 -0800583 * Parameters to this routine are always copied using a small buffer;
David Brownell33e34dc2007-05-08 00:32:21 -0700584 * portable code should never use this for more than 32 bytes.
585 * Performance-sensitive or bulk transfer code should instead use
David Brownell0c868462006-01-08 13:34:25 -0800586 * spi_{async,sync}() calls with dma-safe buffers.
David Brownell8ae12a02006-01-08 13:34:19 -0800587 */
588int spi_write_then_read(struct spi_device *spi,
589 const u8 *txbuf, unsigned n_tx,
590 u8 *rxbuf, unsigned n_rx)
591{
592 static DECLARE_MUTEX(lock);
593
594 int status;
595 struct spi_message message;
596 struct spi_transfer x[2];
597 u8 *local_buf;
598
599 /* Use preallocated DMA-safe buffer. We can't avoid copying here,
600 * (as a pure convenience thing), but we can keep heap costs
601 * out of the hot path ...
602 */
603 if ((n_tx + n_rx) > SPI_BUFSIZ)
604 return -EINVAL;
605
Vitaly Wool8275c642006-01-08 13:34:28 -0800606 spi_message_init(&message);
607 memset(x, 0, sizeof x);
608 if (n_tx) {
609 x[0].len = n_tx;
610 spi_message_add_tail(&x[0], &message);
611 }
612 if (n_rx) {
613 x[1].len = n_rx;
614 spi_message_add_tail(&x[1], &message);
615 }
616
David Brownell8ae12a02006-01-08 13:34:19 -0800617 /* ... unless someone else is using the pre-allocated buffer */
618 if (down_trylock(&lock)) {
619 local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
620 if (!local_buf)
621 return -ENOMEM;
622 } else
623 local_buf = buf;
624
David Brownell8ae12a02006-01-08 13:34:19 -0800625 memcpy(local_buf, txbuf, n_tx);
626 x[0].tx_buf = local_buf;
David Brownell8ae12a02006-01-08 13:34:19 -0800627 x[1].rx_buf = local_buf + n_tx;
David Brownell8ae12a02006-01-08 13:34:19 -0800628
629 /* do the i/o */
David Brownell8ae12a02006-01-08 13:34:19 -0800630 status = spi_sync(spi, &message);
631 if (status == 0) {
632 memcpy(rxbuf, x[1].rx_buf, n_rx);
633 status = message.status;
634 }
635
636 if (x[0].tx_buf == buf)
637 up(&lock);
638 else
639 kfree(local_buf);
640
641 return status;
642}
643EXPORT_SYMBOL_GPL(spi_write_then_read);
644
645/*-------------------------------------------------------------------------*/
646
647static int __init spi_init(void)
648{
David Brownellb8852442006-01-08 13:34:23 -0800649 int status;
David Brownell8ae12a02006-01-08 13:34:19 -0800650
Christoph Lametere94b1762006-12-06 20:33:17 -0800651 buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
David Brownellb8852442006-01-08 13:34:23 -0800652 if (!buf) {
653 status = -ENOMEM;
654 goto err0;
655 }
656
657 status = bus_register(&spi_bus_type);
658 if (status < 0)
659 goto err1;
660
661 status = class_register(&spi_master_class);
662 if (status < 0)
663 goto err2;
David Brownell8ae12a02006-01-08 13:34:19 -0800664 return 0;
David Brownellb8852442006-01-08 13:34:23 -0800665
666err2:
667 bus_unregister(&spi_bus_type);
668err1:
669 kfree(buf);
670 buf = NULL;
671err0:
672 return status;
David Brownell8ae12a02006-01-08 13:34:19 -0800673}
David Brownellb8852442006-01-08 13:34:23 -0800674
David Brownell8ae12a02006-01-08 13:34:19 -0800675/* board_info is normally registered in arch_initcall(),
676 * but even essential drivers wait till later
David Brownellb8852442006-01-08 13:34:23 -0800677 *
678 * REVISIT only boardinfo really needs static linking. the rest (device and
679 * driver registration) _could_ be dynamically linked (modular) ... costs
680 * include needing to have boardinfo data structures be much more public.
David Brownell8ae12a02006-01-08 13:34:19 -0800681 */
682subsys_initcall(spi_init);
683