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/drivers/spi/spi.c

https://bitbucket.org/slukk/jb-tsm-kernel-4.2
C | 1142 lines | 593 code | 167 blank | 382 comment | 69 complexity | 8f86eb304e0d57b5535cc48f7c2f035d MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
  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. #include <linux/kernel.h>
  21. #include <linux/device.h>
  22. #include <linux/init.h>
  23. #include <linux/cache.h>
  24. #include <linux/mutex.h>
  25. #include <linux/of_device.h>
  26. #include <linux/slab.h>
  27. #include <linux/mod_devicetable.h>
  28. #include <linux/spi/spi.h>
  29. #include <linux/of_spi.h>
  30. #include <linux/pm_runtime.h>
  31. static void spidev_release(struct device *dev)
  32. {
  33. struct spi_device *spi = to_spi_device(dev);
  34. /* spi masters may cleanup for released devices */
  35. if (spi->master->cleanup)
  36. spi->master->cleanup(spi);
  37. spi_master_put(spi->master);
  38. kfree(spi);
  39. }
  40. static ssize_t
  41. modalias_show(struct device *dev, struct device_attribute *a, char *buf)
  42. {
  43. const struct spi_device *spi = to_spi_device(dev);
  44. return sprintf(buf, "%s\n", spi->modalias);
  45. }
  46. static struct device_attribute spi_dev_attrs[] = {
  47. __ATTR_RO(modalias),
  48. __ATTR_NULL,
  49. };
  50. /* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
  51. * and the sysfs version makes coldplug work too.
  52. */
  53. static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
  54. const struct spi_device *sdev)
  55. {
  56. while (id->name[0]) {
  57. if (!strcmp(sdev->modalias, id->name))
  58. return id;
  59. id++;
  60. }
  61. return NULL;
  62. }
  63. const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
  64. {
  65. const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
  66. return spi_match_id(sdrv->id_table, sdev);
  67. }
  68. EXPORT_SYMBOL_GPL(spi_get_device_id);
  69. static int spi_match_device(struct device *dev, struct device_driver *drv)
  70. {
  71. const struct spi_device *spi = to_spi_device(dev);
  72. const struct spi_driver *sdrv = to_spi_driver(drv);
  73. /* Attempt an OF style match */
  74. if (of_driver_match_device(dev, drv))
  75. return 1;
  76. if (sdrv->id_table)
  77. return !!spi_match_id(sdrv->id_table, spi);
  78. return strcmp(spi->modalias, drv->name) == 0;
  79. }
  80. static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
  81. {
  82. const struct spi_device *spi = to_spi_device(dev);
  83. add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
  84. return 0;
  85. }
  86. #ifdef CONFIG_PM_SLEEP
  87. static int spi_legacy_suspend(struct device *dev, pm_message_t message)
  88. {
  89. int value = 0;
  90. struct spi_driver *drv = to_spi_driver(dev->driver);
  91. /* suspend will stop irqs and dma; no more i/o */
  92. if (drv) {
  93. if (drv->suspend)
  94. value = drv->suspend(to_spi_device(dev), message);
  95. else
  96. dev_dbg(dev, "... can't suspend\n");
  97. }
  98. return value;
  99. }
  100. static int spi_legacy_resume(struct device *dev)
  101. {
  102. int value = 0;
  103. struct spi_driver *drv = to_spi_driver(dev->driver);
  104. /* resume may restart the i/o queue */
  105. if (drv) {
  106. if (drv->resume)
  107. value = drv->resume(to_spi_device(dev));
  108. else
  109. dev_dbg(dev, "... can't resume\n");
  110. }
  111. return value;
  112. }
  113. static int spi_pm_suspend(struct device *dev)
  114. {
  115. const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
  116. if (pm)
  117. return pm_generic_suspend(dev);
  118. else
  119. return spi_legacy_suspend(dev, PMSG_SUSPEND);
  120. }
  121. static int spi_pm_resume(struct device *dev)
  122. {
  123. const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
  124. if (pm)
  125. return pm_generic_resume(dev);
  126. else
  127. return spi_legacy_resume(dev);
  128. }
  129. static int spi_pm_freeze(struct device *dev)
  130. {
  131. const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
  132. if (pm)
  133. return pm_generic_freeze(dev);
  134. else
  135. return spi_legacy_suspend(dev, PMSG_FREEZE);
  136. }
  137. static int spi_pm_thaw(struct device *dev)
  138. {
  139. const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
  140. if (pm)
  141. return pm_generic_thaw(dev);
  142. else
  143. return spi_legacy_resume(dev);
  144. }
  145. static int spi_pm_poweroff(struct device *dev)
  146. {
  147. const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
  148. if (pm)
  149. return pm_generic_poweroff(dev);
  150. else
  151. return spi_legacy_suspend(dev, PMSG_HIBERNATE);
  152. }
  153. static int spi_pm_restore(struct device *dev)
  154. {
  155. const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
  156. if (pm)
  157. return pm_generic_restore(dev);
  158. else
  159. return spi_legacy_resume(dev);
  160. }
  161. #else
  162. #define spi_pm_suspend NULL
  163. #define spi_pm_resume NULL
  164. #define spi_pm_freeze NULL
  165. #define spi_pm_thaw NULL
  166. #define spi_pm_poweroff NULL
  167. #define spi_pm_restore NULL
  168. #endif
  169. static const struct dev_pm_ops spi_pm = {
  170. .suspend = spi_pm_suspend,
  171. .resume = spi_pm_resume,
  172. .freeze = spi_pm_freeze,
  173. .thaw = spi_pm_thaw,
  174. .poweroff = spi_pm_poweroff,
  175. .restore = spi_pm_restore,
  176. SET_RUNTIME_PM_OPS(
  177. pm_generic_runtime_suspend,
  178. pm_generic_runtime_resume,
  179. pm_generic_runtime_idle
  180. )
  181. };
  182. struct bus_type spi_bus_type = {
  183. .name = "spi",
  184. .dev_attrs = spi_dev_attrs,
  185. .match = spi_match_device,
  186. .uevent = spi_uevent,
  187. .pm = &spi_pm,
  188. };
  189. EXPORT_SYMBOL_GPL(spi_bus_type);
  190. static int spi_drv_probe(struct device *dev)
  191. {
  192. const struct spi_driver *sdrv = to_spi_driver(dev->driver);
  193. return sdrv->probe(to_spi_device(dev));
  194. }
  195. static int spi_drv_remove(struct device *dev)
  196. {
  197. const struct spi_driver *sdrv = to_spi_driver(dev->driver);
  198. return sdrv->remove(to_spi_device(dev));
  199. }
  200. static void spi_drv_shutdown(struct device *dev)
  201. {
  202. const struct spi_driver *sdrv = to_spi_driver(dev->driver);
  203. sdrv->shutdown(to_spi_device(dev));
  204. }
  205. /**
  206. * spi_register_driver - register a SPI driver
  207. * @sdrv: the driver to register
  208. * Context: can sleep
  209. */
  210. int spi_register_driver(struct spi_driver *sdrv)
  211. {
  212. sdrv->driver.bus = &spi_bus_type;
  213. if (sdrv->probe)
  214. sdrv->driver.probe = spi_drv_probe;
  215. if (sdrv->remove)
  216. sdrv->driver.remove = spi_drv_remove;
  217. if (sdrv->shutdown)
  218. sdrv->driver.shutdown = spi_drv_shutdown;
  219. return driver_register(&sdrv->driver);
  220. }
  221. EXPORT_SYMBOL_GPL(spi_register_driver);
  222. /*-------------------------------------------------------------------------*/
  223. /* SPI devices should normally not be created by SPI device drivers; that
  224. * would make them board-specific. Similarly with SPI master drivers.
  225. * Device registration normally goes into like arch/.../mach.../board-YYY.c
  226. * with other readonly (flashable) information about mainboard devices.
  227. */
  228. struct boardinfo {
  229. struct list_head list;
  230. struct spi_board_info board_info;
  231. };
  232. static LIST_HEAD(board_list);
  233. static LIST_HEAD(spi_master_list);
  234. /*
  235. * Used to protect add/del opertion for board_info list and
  236. * spi_master list, and their matching process
  237. */
  238. static DEFINE_MUTEX(board_lock);
  239. /**
  240. * spi_alloc_device - Allocate a new SPI device
  241. * @master: Controller to which device is connected
  242. * Context: can sleep
  243. *
  244. * Allows a driver to allocate and initialize a spi_device without
  245. * registering it immediately. This allows a driver to directly
  246. * fill the spi_device with device parameters before calling
  247. * spi_add_device() on it.
  248. *
  249. * Caller is responsible to call spi_add_device() on the returned
  250. * spi_device structure to add it to the SPI master. If the caller
  251. * needs to discard the spi_device without adding it, then it should
  252. * call spi_dev_put() on it.
  253. *
  254. * Returns a pointer to the new device, or NULL.
  255. */
  256. struct spi_device *spi_alloc_device(struct spi_master *master)
  257. {
  258. struct spi_device *spi;
  259. struct device *dev = master->dev.parent;
  260. if (!spi_master_get(master))
  261. return NULL;
  262. spi = kzalloc(sizeof *spi, GFP_KERNEL);
  263. if (!spi) {
  264. dev_err(dev, "cannot alloc spi_device\n");
  265. spi_master_put(master);
  266. return NULL;
  267. }
  268. spi->master = master;
  269. spi->dev.parent = &master->dev;
  270. spi->dev.bus = &spi_bus_type;
  271. spi->dev.release = spidev_release;
  272. device_initialize(&spi->dev);
  273. return spi;
  274. }
  275. EXPORT_SYMBOL_GPL(spi_alloc_device);
  276. /**
  277. * spi_add_device - Add spi_device allocated with spi_alloc_device
  278. * @spi: spi_device to register
  279. *
  280. * Companion function to spi_alloc_device. Devices allocated with
  281. * spi_alloc_device can be added onto the spi bus with this function.
  282. *
  283. * Returns 0 on success; negative errno on failure
  284. */
  285. int spi_add_device(struct spi_device *spi)
  286. {
  287. static DEFINE_MUTEX(spi_add_lock);
  288. struct device *dev = spi->master->dev.parent;
  289. struct device *d;
  290. int status;
  291. /* Chipselects are numbered 0..max; validate. */
  292. if (spi->chip_select >= spi->master->num_chipselect) {
  293. dev_err(dev, "cs%d >= max %d\n",
  294. spi->chip_select,
  295. spi->master->num_chipselect);
  296. return -EINVAL;
  297. }
  298. /* Set the bus ID string */
  299. dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
  300. spi->chip_select);
  301. /* We need to make sure there's no other device with this
  302. * chipselect **BEFORE** we call setup(), else we'll trash
  303. * its configuration. Lock against concurrent add() calls.
  304. */
  305. mutex_lock(&spi_add_lock);
  306. d = bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));
  307. if (d != NULL) {
  308. dev_err(dev, "chipselect %d already in use\n",
  309. spi->chip_select);
  310. put_device(d);
  311. status = -EBUSY;
  312. goto done;
  313. }
  314. /* Drivers may modify this initial i/o setup, but will
  315. * normally rely on the device being setup. Devices
  316. * using SPI_CS_HIGH can't coexist well otherwise...
  317. */
  318. status = spi_setup(spi);
  319. if (status < 0) {
  320. dev_err(dev, "can't setup %s, status %d\n",
  321. dev_name(&spi->dev), status);
  322. goto done;
  323. }
  324. /* Device may be bound to an active driver when this returns */
  325. status = device_add(&spi->dev);
  326. if (status < 0)
  327. dev_err(dev, "can't add %s, status %d\n",
  328. dev_name(&spi->dev), status);
  329. else
  330. dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
  331. done:
  332. mutex_unlock(&spi_add_lock);
  333. return status;
  334. }
  335. EXPORT_SYMBOL_GPL(spi_add_device);
  336. /**
  337. * spi_new_device - instantiate one new SPI device
  338. * @master: Controller to which device is connected
  339. * @chip: Describes the SPI device
  340. * Context: can sleep
  341. *
  342. * On typical mainboards, this is purely internal; and it's not needed
  343. * after board init creates the hard-wired devices. Some development
  344. * platforms may not be able to use spi_register_board_info though, and
  345. * this is exported so that for example a USB or parport based adapter
  346. * driver could add devices (which it would learn about out-of-band).
  347. *
  348. * Returns the new device, or NULL.
  349. */
  350. struct spi_device *spi_new_device(struct spi_master *master,
  351. struct spi_board_info *chip)
  352. {
  353. struct spi_device *proxy;
  354. int status;
  355. /* NOTE: caller did any chip->bus_num checks necessary.
  356. *
  357. * Also, unless we change the return value convention to use
  358. * error-or-pointer (not NULL-or-pointer), troubleshootability
  359. * suggests syslogged diagnostics are best here (ugh).
  360. */
  361. proxy = spi_alloc_device(master);
  362. if (!proxy)
  363. return NULL;
  364. WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
  365. proxy->chip_select = chip->chip_select;
  366. proxy->max_speed_hz = chip->max_speed_hz;
  367. proxy->mode = chip->mode;
  368. proxy->irq = chip->irq;
  369. strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
  370. proxy->dev.platform_data = (void *) chip->platform_data;
  371. proxy->controller_data = chip->controller_data;
  372. proxy->controller_state = NULL;
  373. status = spi_add_device(proxy);
  374. if (status < 0) {
  375. spi_dev_put(proxy);
  376. return NULL;
  377. }
  378. return proxy;
  379. }
  380. EXPORT_SYMBOL_GPL(spi_new_device);
  381. static void spi_match_master_to_boardinfo(struct spi_master *master,
  382. struct spi_board_info *bi)
  383. {
  384. struct spi_device *dev;
  385. if (master->bus_num != bi->bus_num)
  386. return;
  387. dev = spi_new_device(master, bi);
  388. if (!dev)
  389. dev_err(master->dev.parent, "can't create new device for %s\n",
  390. bi->modalias);
  391. }
  392. /**
  393. * spi_register_board_info - register SPI devices for a given board
  394. * @info: array of chip descriptors
  395. * @n: how many descriptors are provided
  396. * Context: can sleep
  397. *
  398. * Board-specific early init code calls this (probably during arch_initcall)
  399. * with segments of the SPI device table. Any device nodes are created later,
  400. * after the relevant parent SPI controller (bus_num) is defined. We keep
  401. * this table of devices forever, so that reloading a controller driver will
  402. * not make Linux forget about these hard-wired devices.
  403. *
  404. * Other code can also call this, e.g. a particular add-on board might provide
  405. * SPI devices through its expansion connector, so code initializing that board
  406. * would naturally declare its SPI devices.
  407. *
  408. * The board info passed can safely be __initdata ... but be careful of
  409. * any embedded pointers (platform_data, etc), they're copied as-is.
  410. */
  411. int __init
  412. spi_register_board_info(struct spi_board_info const *info, unsigned n)
  413. {
  414. struct boardinfo *bi;
  415. int i;
  416. bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
  417. if (!bi)
  418. return -ENOMEM;
  419. for (i = 0; i < n; i++, bi++, info++) {
  420. struct spi_master *master;
  421. memcpy(&bi->board_info, info, sizeof(*info));
  422. mutex_lock(&board_lock);
  423. list_add_tail(&bi->list, &board_list);
  424. list_for_each_entry(master, &spi_master_list, list)
  425. spi_match_master_to_boardinfo(master, &bi->board_info);
  426. mutex_unlock(&board_lock);
  427. }
  428. return 0;
  429. }
  430. /*-------------------------------------------------------------------------*/
  431. static void spi_master_release(struct device *dev)
  432. {
  433. struct spi_master *master;
  434. master = container_of(dev, struct spi_master, dev);
  435. kfree(master);
  436. }
  437. static struct class spi_master_class = {
  438. .name = "spi_master",
  439. .owner = THIS_MODULE,
  440. .dev_release = spi_master_release,
  441. };
  442. /**
  443. * spi_alloc_master - allocate SPI master controller
  444. * @dev: the controller, possibly using the platform_bus
  445. * @size: how much zeroed driver-private data to allocate; the pointer to this
  446. * memory is in the driver_data field of the returned device,
  447. * accessible with spi_master_get_devdata().
  448. * Context: can sleep
  449. *
  450. * This call is used only by SPI master controller drivers, which are the
  451. * only ones directly touching chip registers. It's how they allocate
  452. * an spi_master structure, prior to calling spi_register_master().
  453. *
  454. * This must be called from context that can sleep. It returns the SPI
  455. * master structure on success, else NULL.
  456. *
  457. * The caller is responsible for assigning the bus number and initializing
  458. * the master's methods before calling spi_register_master(); and (after errors
  459. * adding the device) calling spi_master_put() to prevent a memory leak.
  460. */
  461. struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
  462. {
  463. struct spi_master *master;
  464. if (!dev)
  465. return NULL;
  466. master = kzalloc(size + sizeof *master, GFP_KERNEL);
  467. if (!master)
  468. return NULL;
  469. device_initialize(&master->dev);
  470. master->dev.class = &spi_master_class;
  471. master->dev.parent = get_device(dev);
  472. spi_master_set_devdata(master, &master[1]);
  473. return master;
  474. }
  475. EXPORT_SYMBOL_GPL(spi_alloc_master);
  476. /**
  477. * spi_register_master - register SPI master controller
  478. * @master: initialized master, originally from spi_alloc_master()
  479. * Context: can sleep
  480. *
  481. * SPI master controllers connect to their drivers using some non-SPI bus,
  482. * such as the platform bus. The final stage of probe() in that code
  483. * includes calling spi_register_master() to hook up to this SPI bus glue.
  484. *
  485. * SPI controllers use board specific (often SOC specific) bus numbers,
  486. * and board-specific addressing for SPI devices combines those numbers
  487. * with chip select numbers. Since SPI does not directly support dynamic
  488. * device identification, boards need configuration tables telling which
  489. * chip is at which address.
  490. *
  491. * This must be called from context that can sleep. It returns zero on
  492. * success, else a negative error code (dropping the master's refcount).
  493. * After a successful return, the caller is responsible for calling
  494. * spi_unregister_master().
  495. */
  496. int spi_register_master(struct spi_master *master)
  497. {
  498. static atomic_t dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
  499. struct device *dev = master->dev.parent;
  500. struct boardinfo *bi;
  501. int status = -ENODEV;
  502. int dynamic = 0;
  503. if (!dev)
  504. return -ENODEV;
  505. /* even if it's just one always-selected device, there must
  506. * be at least one chipselect
  507. */
  508. if (master->num_chipselect == 0)
  509. return -EINVAL;
  510. /* convention: dynamically assigned bus IDs count down from the max */
  511. if (master->bus_num < 0) {
  512. /* FIXME switch to an IDR based scheme, something like
  513. * I2C now uses, so we can't run out of "dynamic" IDs
  514. */
  515. master->bus_num = atomic_dec_return(&dyn_bus_id);
  516. dynamic = 1;
  517. }
  518. spin_lock_init(&master->bus_lock_spinlock);
  519. mutex_init(&master->bus_lock_mutex);
  520. master->bus_lock_flag = 0;
  521. /* register the device, then userspace will see it.
  522. * registration fails if the bus ID is in use.
  523. */
  524. dev_set_name(&master->dev, "spi%u", master->bus_num);
  525. status = device_add(&master->dev);
  526. if (status < 0)
  527. goto done;
  528. dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
  529. dynamic ? " (dynamic)" : "");
  530. mutex_lock(&board_lock);
  531. list_add_tail(&master->list, &spi_master_list);
  532. list_for_each_entry(bi, &board_list, list)
  533. spi_match_master_to_boardinfo(master, &bi->board_info);
  534. mutex_unlock(&board_lock);
  535. status = 0;
  536. /* Register devices from the device tree */
  537. of_register_spi_devices(master);
  538. done:
  539. return status;
  540. }
  541. EXPORT_SYMBOL_GPL(spi_register_master);
  542. static int __unregister(struct device *dev, void *null)
  543. {
  544. spi_unregister_device(to_spi_device(dev));
  545. return 0;
  546. }
  547. /**
  548. * spi_unregister_master - unregister SPI master controller
  549. * @master: the master being unregistered
  550. * Context: can sleep
  551. *
  552. * This call is used only by SPI master controller drivers, which are the
  553. * only ones directly touching chip registers.
  554. *
  555. * This must be called from context that can sleep.
  556. */
  557. void spi_unregister_master(struct spi_master *master)
  558. {
  559. int dummy;
  560. mutex_lock(&board_lock);
  561. list_del(&master->list);
  562. mutex_unlock(&board_lock);
  563. dummy = device_for_each_child(&master->dev, NULL, __unregister);
  564. device_unregister(&master->dev);
  565. }
  566. EXPORT_SYMBOL_GPL(spi_unregister_master);
  567. static int __spi_master_match(struct device *dev, void *data)
  568. {
  569. struct spi_master *m;
  570. u16 *bus_num = data;
  571. m = container_of(dev, struct spi_master, dev);
  572. return m->bus_num == *bus_num;
  573. }
  574. /**
  575. * spi_busnum_to_master - look up master associated with bus_num
  576. * @bus_num: the master's bus number
  577. * Context: can sleep
  578. *
  579. * This call may be used with devices that are registered after
  580. * arch init time. It returns a refcounted pointer to the relevant
  581. * spi_master (which the caller must release), or NULL if there is
  582. * no such master registered.
  583. */
  584. struct spi_master *spi_busnum_to_master(u16 bus_num)
  585. {
  586. struct device *dev;
  587. struct spi_master *master = NULL;
  588. dev = class_find_device(&spi_master_class, NULL, &bus_num,
  589. __spi_master_match);
  590. if (dev)
  591. master = container_of(dev, struct spi_master, dev);
  592. /* reference got in class_find_device */
  593. return master;
  594. }
  595. EXPORT_SYMBOL_GPL(spi_busnum_to_master);
  596. /*-------------------------------------------------------------------------*/
  597. /* Core methods for SPI master protocol drivers. Some of the
  598. * other core methods are currently defined as inline functions.
  599. */
  600. /**
  601. * spi_setup - setup SPI mode and clock rate
  602. * @spi: the device whose settings are being modified
  603. * Context: can sleep, and no requests are queued to the device
  604. *
  605. * SPI protocol drivers may need to update the transfer mode if the
  606. * device doesn't work with its default. They may likewise need
  607. * to update clock rates or word sizes from initial values. This function
  608. * changes those settings, and must be called from a context that can sleep.
  609. * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
  610. * effect the next time the device is selected and data is transferred to
  611. * or from it. When this function returns, the spi device is deselected.
  612. *
  613. * Note that this call will fail if the protocol driver specifies an option
  614. * that the underlying controller or its driver does not support. For
  615. * example, not all hardware supports wire transfers using nine bit words,
  616. * LSB-first wire encoding, or active-high chipselects.
  617. */
  618. int spi_setup(struct spi_device *spi)
  619. {
  620. unsigned bad_bits;
  621. int status;
  622. /* help drivers fail *cleanly* when they need options
  623. * that aren't supported with their current master
  624. */
  625. bad_bits = spi->mode & ~spi->master->mode_bits;
  626. if (bad_bits) {
  627. dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
  628. bad_bits);
  629. return -EINVAL;
  630. }
  631. if (!spi->bits_per_word)
  632. spi->bits_per_word = 8;
  633. status = spi->master->setup(spi);
  634. dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
  635. "%u bits/w, %u Hz max --> %d\n",
  636. (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
  637. (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
  638. (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
  639. (spi->mode & SPI_3WIRE) ? "3wire, " : "",
  640. (spi->mode & SPI_LOOP) ? "loopback, " : "",
  641. spi->bits_per_word, spi->max_speed_hz,
  642. status);
  643. return status;
  644. }
  645. EXPORT_SYMBOL_GPL(spi_setup);
  646. static int __spi_async(struct spi_device *spi, struct spi_message *message)
  647. {
  648. struct spi_master *master = spi->master;
  649. /* Half-duplex links include original MicroWire, and ones with
  650. * only one data pin like SPI_3WIRE (switches direction) or where
  651. * either MOSI or MISO is missing. They can also be caused by
  652. * software limitations.
  653. */
  654. if ((master->flags & SPI_MASTER_HALF_DUPLEX)
  655. || (spi->mode & SPI_3WIRE)) {
  656. struct spi_transfer *xfer;
  657. unsigned flags = master->flags;
  658. list_for_each_entry(xfer, &message->transfers, transfer_list) {
  659. if (xfer->rx_buf && xfer->tx_buf)
  660. return -EINVAL;
  661. if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
  662. return -EINVAL;
  663. if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
  664. return -EINVAL;
  665. }
  666. }
  667. message->spi = spi;
  668. message->status = -EINPROGRESS;
  669. return master->transfer(spi, message);
  670. }
  671. /**
  672. * spi_async - asynchronous SPI transfer
  673. * @spi: device with which data will be exchanged
  674. * @message: describes the data transfers, including completion callback
  675. * Context: any (irqs may be blocked, etc)
  676. *
  677. * This call may be used in_irq and other contexts which can't sleep,
  678. * as well as from task contexts which can sleep.
  679. *
  680. * The completion callback is invoked in a context which can't sleep.
  681. * Before that invocation, the value of message->status is undefined.
  682. * When the callback is issued, message->status holds either zero (to
  683. * indicate complete success) or a negative error code. After that
  684. * callback returns, the driver which issued the transfer request may
  685. * deallocate the associated memory; it's no longer in use by any SPI
  686. * core or controller driver code.
  687. *
  688. * Note that although all messages to a spi_device are handled in
  689. * FIFO order, messages may go to different devices in other orders.
  690. * Some device might be higher priority, or have various "hard" access
  691. * time requirements, for example.
  692. *
  693. * On detection of any fault during the transfer, processing of
  694. * the entire message is aborted, and the device is deselected.
  695. * Until returning from the associated message completion callback,
  696. * no other spi_message queued to that device will be processed.
  697. * (This rule applies equally to all the synchronous transfer calls,
  698. * which are wrappers around this core asynchronous primitive.)
  699. */
  700. int spi_async(struct spi_device *spi, struct spi_message *message)
  701. {
  702. struct spi_master *master = spi->master;
  703. int ret;
  704. unsigned long flags;
  705. spin_lock_irqsave(&master->bus_lock_spinlock, flags);
  706. if (master->bus_lock_flag)
  707. ret = -EBUSY;
  708. else
  709. ret = __spi_async(spi, message);
  710. spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
  711. return ret;
  712. }
  713. EXPORT_SYMBOL_GPL(spi_async);
  714. /**
  715. * spi_async_locked - version of spi_async with exclusive bus usage
  716. * @spi: device with which data will be exchanged
  717. * @message: describes the data transfers, including completion callback
  718. * Context: any (irqs may be blocked, etc)
  719. *
  720. * This call may be used in_irq and other contexts which can't sleep,
  721. * as well as from task contexts which can sleep.
  722. *
  723. * The completion callback is invoked in a context which can't sleep.
  724. * Before that invocation, the value of message->status is undefined.
  725. * When the callback is issued, message->status holds either zero (to
  726. * indicate complete success) or a negative error code. After that
  727. * callback returns, the driver which issued the transfer request may
  728. * deallocate the associated memory; it's no longer in use by any SPI
  729. * core or controller driver code.
  730. *
  731. * Note that although all messages to a spi_device are handled in
  732. * FIFO order, messages may go to different devices in other orders.
  733. * Some device might be higher priority, or have various "hard" access
  734. * time requirements, for example.
  735. *
  736. * On detection of any fault during the transfer, processing of
  737. * the entire message is aborted, and the device is deselected.
  738. * Until returning from the associated message completion callback,
  739. * no other spi_message queued to that device will be processed.
  740. * (This rule applies equally to all the synchronous transfer calls,
  741. * which are wrappers around this core asynchronous primitive.)
  742. */
  743. int spi_async_locked(struct spi_device *spi, struct spi_message *message)
  744. {
  745. struct spi_master *master = spi->master;
  746. int ret;
  747. unsigned long flags;
  748. spin_lock_irqsave(&master->bus_lock_spinlock, flags);
  749. ret = __spi_async(spi, message);
  750. spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
  751. return ret;
  752. }
  753. EXPORT_SYMBOL_GPL(spi_async_locked);
  754. /*-------------------------------------------------------------------------*/
  755. /* Utility methods for SPI master protocol drivers, layered on
  756. * top of the core. Some other utility methods are defined as
  757. * inline functions.
  758. */
  759. static void spi_complete(void *arg)
  760. {
  761. complete(arg);
  762. }
  763. static int __spi_sync(struct spi_device *spi, struct spi_message *message,
  764. int bus_locked)
  765. {
  766. DECLARE_COMPLETION_ONSTACK(done);
  767. int status;
  768. struct spi_master *master = spi->master;
  769. message->complete = spi_complete;
  770. message->context = &done;
  771. if (!bus_locked)
  772. mutex_lock(&master->bus_lock_mutex);
  773. status = spi_async_locked(spi, message);
  774. if (!bus_locked)
  775. mutex_unlock(&master->bus_lock_mutex);
  776. if (status == 0) {
  777. wait_for_completion(&done);
  778. status = message->status;
  779. }
  780. message->context = NULL;
  781. return status;
  782. }
  783. /**
  784. * spi_sync - blocking/synchronous SPI data transfers
  785. * @spi: device with which data will be exchanged
  786. * @message: describes the data transfers
  787. * Context: can sleep
  788. *
  789. * This call may only be used from a context that may sleep. The sleep
  790. * is non-interruptible, and has no timeout. Low-overhead controller
  791. * drivers may DMA directly into and out of the message buffers.
  792. *
  793. * Note that the SPI device's chip select is active during the message,
  794. * and then is normally disabled between messages. Drivers for some
  795. * frequently-used devices may want to minimize costs of selecting a chip,
  796. * by leaving it selected in anticipation that the next message will go
  797. * to the same chip. (That may increase power usage.)
  798. *
  799. * Also, the caller is guaranteeing that the memory associated with the
  800. * message will not be freed before this call returns.
  801. *
  802. * It returns zero on success, else a negative error code.
  803. */
  804. int spi_sync(struct spi_device *spi, struct spi_message *message)
  805. {
  806. return __spi_sync(spi, message, 0);
  807. }
  808. EXPORT_SYMBOL_GPL(spi_sync);
  809. /**
  810. * spi_sync_locked - version of spi_sync with exclusive bus usage
  811. * @spi: device with which data will be exchanged
  812. * @message: describes the data transfers
  813. * Context: can sleep
  814. *
  815. * This call may only be used from a context that may sleep. The sleep
  816. * is non-interruptible, and has no timeout. Low-overhead controller
  817. * drivers may DMA directly into and out of the message buffers.
  818. *
  819. * This call should be used by drivers that require exclusive access to the
  820. * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
  821. * be released by a spi_bus_unlock call when the exclusive access is over.
  822. *
  823. * It returns zero on success, else a negative error code.
  824. */
  825. int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
  826. {
  827. return __spi_sync(spi, message, 1);
  828. }
  829. EXPORT_SYMBOL_GPL(spi_sync_locked);
  830. /**
  831. * spi_bus_lock - obtain a lock for exclusive SPI bus usage
  832. * @master: SPI bus master that should be locked for exclusive bus access
  833. * Context: can sleep
  834. *
  835. * This call may only be used from a context that may sleep. The sleep
  836. * is non-interruptible, and has no timeout.
  837. *
  838. * This call should be used by drivers that require exclusive access to the
  839. * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
  840. * exclusive access is over. Data transfer must be done by spi_sync_locked
  841. * and spi_async_locked calls when the SPI bus lock is held.
  842. *
  843. * It returns zero on success, else a negative error code.
  844. */
  845. int spi_bus_lock(struct spi_master *master)
  846. {
  847. unsigned long flags;
  848. mutex_lock(&master->bus_lock_mutex);
  849. spin_lock_irqsave(&master->bus_lock_spinlock, flags);
  850. master->bus_lock_flag = 1;
  851. spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
  852. /* mutex remains locked until spi_bus_unlock is called */
  853. return 0;
  854. }
  855. EXPORT_SYMBOL_GPL(spi_bus_lock);
  856. /**
  857. * spi_bus_unlock - release the lock for exclusive SPI bus usage
  858. * @master: SPI bus master that was locked for exclusive bus access
  859. * Context: can sleep
  860. *
  861. * This call may only be used from a context that may sleep. The sleep
  862. * is non-interruptible, and has no timeout.
  863. *
  864. * This call releases an SPI bus lock previously obtained by an spi_bus_lock
  865. * call.
  866. *
  867. * It returns zero on success, else a negative error code.
  868. */
  869. int spi_bus_unlock(struct spi_master *master)
  870. {
  871. master->bus_lock_flag = 0;
  872. mutex_unlock(&master->bus_lock_mutex);
  873. return 0;
  874. }
  875. EXPORT_SYMBOL_GPL(spi_bus_unlock);
  876. /* portable code must never pass more than 32 bytes */
  877. #define SPI_BUFSIZ max(32,SMP_CACHE_BYTES)
  878. static u8 *buf;
  879. /**
  880. * spi_write_then_read - SPI synchronous write followed by read
  881. * @spi: device with which data will be exchanged
  882. * @txbuf: data to be written (need not be dma-safe)
  883. * @n_tx: size of txbuf, in bytes
  884. * @rxbuf: buffer into which data will be read (need not be dma-safe)
  885. * @n_rx: size of rxbuf, in bytes
  886. * Context: can sleep
  887. *
  888. * This performs a half duplex MicroWire style transaction with the
  889. * device, sending txbuf and then reading rxbuf. The return value
  890. * is zero for success, else a negative errno status code.
  891. * This call may only be used from a context that may sleep.
  892. *
  893. * Parameters to this routine are always copied using a small buffer;
  894. * portable code should never use this for more than 32 bytes.
  895. * Performance-sensitive or bulk transfer code should instead use
  896. * spi_{async,sync}() calls with dma-safe buffers.
  897. */
  898. int spi_write_then_read(struct spi_device *spi,
  899. const void *txbuf, unsigned n_tx,
  900. void *rxbuf, unsigned n_rx)
  901. {
  902. static DEFINE_MUTEX(lock);
  903. int status;
  904. struct spi_message message;
  905. struct spi_transfer x[2];
  906. u8 *local_buf;
  907. /* Use preallocated DMA-safe buffer. We can't avoid copying here,
  908. * (as a pure convenience thing), but we can keep heap costs
  909. * out of the hot path ...
  910. */
  911. if ((n_tx + n_rx) > SPI_BUFSIZ)
  912. return -EINVAL;
  913. spi_message_init(&message);
  914. memset(x, 0, sizeof x);
  915. if (n_tx) {
  916. x[0].len = n_tx;
  917. spi_message_add_tail(&x[0], &message);
  918. }
  919. if (n_rx) {
  920. x[1].len = n_rx;
  921. spi_message_add_tail(&x[1], &message);
  922. }
  923. /* ... unless someone else is using the pre-allocated buffer */
  924. if (!mutex_trylock(&lock)) {
  925. local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
  926. if (!local_buf)
  927. return -ENOMEM;
  928. } else
  929. local_buf = buf;
  930. memcpy(local_buf, txbuf, n_tx);
  931. x[0].tx_buf = local_buf;
  932. x[1].rx_buf = local_buf + n_tx;
  933. /* do the i/o */
  934. status = spi_sync(spi, &message);
  935. if (status == 0)
  936. memcpy(rxbuf, x[1].rx_buf, n_rx);
  937. if (x[0].tx_buf == buf)
  938. mutex_unlock(&lock);
  939. else
  940. kfree(local_buf);
  941. return status;
  942. }
  943. EXPORT_SYMBOL_GPL(spi_write_then_read);
  944. /*-------------------------------------------------------------------------*/
  945. static int __init spi_init(void)
  946. {
  947. int status;
  948. buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
  949. if (!buf) {
  950. status = -ENOMEM;
  951. goto err0;
  952. }
  953. status = bus_register(&spi_bus_type);
  954. if (status < 0)
  955. goto err1;
  956. status = class_register(&spi_master_class);
  957. if (status < 0)
  958. goto err2;
  959. return 0;
  960. err2:
  961. bus_unregister(&spi_bus_type);
  962. err1:
  963. kfree(buf);
  964. buf = NULL;
  965. err0:
  966. return status;
  967. }
  968. /* board_info is normally registered in arch_initcall(),
  969. * but even essential drivers wait till later
  970. *
  971. * REVISIT only boardinfo really needs static linking. the rest (device and
  972. * driver registration) _could_ be dynamically linked (modular) ... costs
  973. * include needing to have boardinfo data structures be much more public.
  974. */
  975. postcore_initcall(spi_init);