linux/drivers/spi/spi.c
<<
>>
Prefs
   1/*
   2 * SPI init/core code
   3 *
   4 * Copyright (C) 2005 David Brownell
   5 * Copyright (C) 2008 Secret Lab Technologies Ltd.
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License as published by
   9 * the Free Software Foundation; either version 2 of the License, or
  10 * (at your option) any later version.
  11 *
  12 * This program is distributed in the hope that it will be useful,
  13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 *
  17 * You should have received a copy of the GNU General Public License
  18 * along with this program; if not, write to the Free Software
  19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22#include <linux/kernel.h>
  23#include <linux/kmod.h>
  24#include <linux/device.h>
  25#include <linux/init.h>
  26#include <linux/cache.h>
  27#include <linux/mutex.h>
  28#include <linux/of_device.h>
  29#include <linux/of_irq.h>
  30#include <linux/slab.h>
  31#include <linux/mod_devicetable.h>
  32#include <linux/spi/spi.h>
  33#include <linux/of_gpio.h>
  34#include <linux/pm_runtime.h>
  35#include <linux/export.h>
  36#include <linux/sched/rt.h>
  37#include <linux/delay.h>
  38#include <linux/kthread.h>
  39#include <linux/ioport.h>
  40#include <linux/acpi.h>
  41
  42static void spidev_release(struct device *dev)
  43{
  44        struct spi_device       *spi = to_spi_device(dev);
  45
  46        /* spi masters may cleanup for released devices */
  47        if (spi->master->cleanup)
  48                spi->master->cleanup(spi);
  49
  50        spi_master_put(spi->master);
  51        kfree(spi);
  52}
  53
  54static ssize_t
  55modalias_show(struct device *dev, struct device_attribute *a, char *buf)
  56{
  57        const struct spi_device *spi = to_spi_device(dev);
  58
  59        return sprintf(buf, "%s%s\n", SPI_MODULE_PREFIX, spi->modalias);
  60}
  61
  62static struct device_attribute spi_dev_attrs[] = {
  63        __ATTR_RO(modalias),
  64        __ATTR_NULL,
  65};
  66
  67/* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
  68 * and the sysfs version makes coldplug work too.
  69 */
  70
  71static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
  72                                                const struct spi_device *sdev)
  73{
  74        while (id->name[0]) {
  75                if (!strcmp(sdev->modalias, id->name))
  76                        return id;
  77                id++;
  78        }
  79        return NULL;
  80}
  81
  82const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
  83{
  84        const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
  85
  86        return spi_match_id(sdrv->id_table, sdev);
  87}
  88EXPORT_SYMBOL_GPL(spi_get_device_id);
  89
  90static int spi_match_device(struct device *dev, struct device_driver *drv)
  91{
  92        const struct spi_device *spi = to_spi_device(dev);
  93        const struct spi_driver *sdrv = to_spi_driver(drv);
  94
  95        /* Attempt an OF style match */
  96        if (of_driver_match_device(dev, drv))
  97                return 1;
  98
  99        /* Then try ACPI */
 100        if (acpi_driver_match_device(dev, drv))
 101                return 1;
 102
 103        if (sdrv->id_table)
 104                return !!spi_match_id(sdrv->id_table, spi);
 105
 106        return strcmp(spi->modalias, drv->name) == 0;
 107}
 108
 109static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
 110{
 111        const struct spi_device         *spi = to_spi_device(dev);
 112
 113        add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
 114        return 0;
 115}
 116
 117#ifdef CONFIG_PM_SLEEP
 118static int spi_legacy_suspend(struct device *dev, pm_message_t message)
 119{
 120        int                     value = 0;
 121        struct spi_driver       *drv = to_spi_driver(dev->driver);
 122
 123        /* suspend will stop irqs and dma; no more i/o */
 124        if (drv) {
 125                if (drv->suspend)
 126                        value = drv->suspend(to_spi_device(dev), message);
 127                else
 128                        dev_dbg(dev, "... can't suspend\n");
 129        }
 130        return value;
 131}
 132
 133static int spi_legacy_resume(struct device *dev)
 134{
 135        int                     value = 0;
 136        struct spi_driver       *drv = to_spi_driver(dev->driver);
 137
 138        /* resume may restart the i/o queue */
 139        if (drv) {
 140                if (drv->resume)
 141                        value = drv->resume(to_spi_device(dev));
 142                else
 143                        dev_dbg(dev, "... can't resume\n");
 144        }
 145        return value;
 146}
 147
 148static int spi_pm_suspend(struct device *dev)
 149{
 150        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 151
 152        if (pm)
 153                return pm_generic_suspend(dev);
 154        else
 155                return spi_legacy_suspend(dev, PMSG_SUSPEND);
 156}
 157
 158static int spi_pm_resume(struct device *dev)
 159{
 160        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 161
 162        if (pm)
 163                return pm_generic_resume(dev);
 164        else
 165                return spi_legacy_resume(dev);
 166}
 167
 168static int spi_pm_freeze(struct device *dev)
 169{
 170        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 171
 172        if (pm)
 173                return pm_generic_freeze(dev);
 174        else
 175                return spi_legacy_suspend(dev, PMSG_FREEZE);
 176}
 177
 178static int spi_pm_thaw(struct device *dev)
 179{
 180        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 181
 182        if (pm)
 183                return pm_generic_thaw(dev);
 184        else
 185                return spi_legacy_resume(dev);
 186}
 187
 188static int spi_pm_poweroff(struct device *dev)
 189{
 190        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 191
 192        if (pm)
 193                return pm_generic_poweroff(dev);
 194        else
 195                return spi_legacy_suspend(dev, PMSG_HIBERNATE);
 196}
 197
 198static int spi_pm_restore(struct device *dev)
 199{
 200        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 201
 202        if (pm)
 203                return pm_generic_restore(dev);
 204        else
 205                return spi_legacy_resume(dev);
 206}
 207#else
 208#define spi_pm_suspend  NULL
 209#define spi_pm_resume   NULL
 210#define spi_pm_freeze   NULL
 211#define spi_pm_thaw     NULL
 212#define spi_pm_poweroff NULL
 213#define spi_pm_restore  NULL
 214#endif
 215
 216static const struct dev_pm_ops spi_pm = {
 217        .suspend = spi_pm_suspend,
 218        .resume = spi_pm_resume,
 219        .freeze = spi_pm_freeze,
 220        .thaw = spi_pm_thaw,
 221        .poweroff = spi_pm_poweroff,
 222        .restore = spi_pm_restore,
 223        SET_RUNTIME_PM_OPS(
 224                pm_generic_runtime_suspend,
 225                pm_generic_runtime_resume,
 226                pm_generic_runtime_idle
 227        )
 228};
 229
 230struct bus_type spi_bus_type = {
 231        .name           = "spi",
 232        .dev_attrs      = spi_dev_attrs,
 233        .match          = spi_match_device,
 234        .uevent         = spi_uevent,
 235        .pm             = &spi_pm,
 236};
 237EXPORT_SYMBOL_GPL(spi_bus_type);
 238
 239
 240static int spi_drv_probe(struct device *dev)
 241{
 242        const struct spi_driver         *sdrv = to_spi_driver(dev->driver);
 243
 244        return sdrv->probe(to_spi_device(dev));
 245}
 246
 247static int spi_drv_remove(struct device *dev)
 248{
 249        const struct spi_driver         *sdrv = to_spi_driver(dev->driver);
 250
 251        return sdrv->remove(to_spi_device(dev));
 252}
 253
 254static void spi_drv_shutdown(struct device *dev)
 255{
 256        const struct spi_driver         *sdrv = to_spi_driver(dev->driver);
 257
 258        sdrv->shutdown(to_spi_device(dev));
 259}
 260
 261/**
 262 * spi_register_driver - register a SPI driver
 263 * @sdrv: the driver to register
 264 * Context: can sleep
 265 */
 266int spi_register_driver(struct spi_driver *sdrv)
 267{
 268        sdrv->driver.bus = &spi_bus_type;
 269        if (sdrv->probe)
 270                sdrv->driver.probe = spi_drv_probe;
 271        if (sdrv->remove)
 272                sdrv->driver.remove = spi_drv_remove;
 273        if (sdrv->shutdown)
 274                sdrv->driver.shutdown = spi_drv_shutdown;
 275        return driver_register(&sdrv->driver);
 276}
 277EXPORT_SYMBOL_GPL(spi_register_driver);
 278
 279/*-------------------------------------------------------------------------*/
 280
 281/* SPI devices should normally not be created by SPI device drivers; that
 282 * would make them board-specific.  Similarly with SPI master drivers.
 283 * Device registration normally goes into like arch/.../mach.../board-YYY.c
 284 * with other readonly (flashable) information about mainboard devices.
 285 */
 286
 287struct boardinfo {
 288        struct list_head        list;
 289        struct spi_board_info   board_info;
 290};
 291
 292static LIST_HEAD(board_list);
 293static LIST_HEAD(spi_master_list);
 294
 295/*
 296 * Used to protect add/del opertion for board_info list and
 297 * spi_master list, and their matching process
 298 */
 299static DEFINE_MUTEX(board_lock);
 300
 301/**
 302 * spi_alloc_device - Allocate a new SPI device
 303 * @master: Controller to which device is connected
 304 * Context: can sleep
 305 *
 306 * Allows a driver to allocate and initialize a spi_device without
 307 * registering it immediately.  This allows a driver to directly
 308 * fill the spi_device with device parameters before calling
 309 * spi_add_device() on it.
 310 *
 311 * Caller is responsible to call spi_add_device() on the returned
 312 * spi_device structure to add it to the SPI master.  If the caller
 313 * needs to discard the spi_device without adding it, then it should
 314 * call spi_dev_put() on it.
 315 *
 316 * Returns a pointer to the new device, or NULL.
 317 */
 318struct spi_device *spi_alloc_device(struct spi_master *master)
 319{
 320        struct spi_device       *spi;
 321        struct device           *dev = master->dev.parent;
 322
 323        if (!spi_master_get(master))
 324                return NULL;
 325
 326        spi = kzalloc(sizeof *spi, GFP_KERNEL);
 327        if (!spi) {
 328                dev_err(dev, "cannot alloc spi_device\n");
 329                spi_master_put(master);
 330                return NULL;
 331        }
 332
 333        spi->master = master;
 334        spi->dev.parent = &master->dev;
 335        spi->dev.bus = &spi_bus_type;
 336        spi->dev.release = spidev_release;
 337        spi->cs_gpio = -EINVAL;
 338        device_initialize(&spi->dev);
 339        return spi;
 340}
 341EXPORT_SYMBOL_GPL(spi_alloc_device);
 342
 343/**
 344 * spi_add_device - Add spi_device allocated with spi_alloc_device
 345 * @spi: spi_device to register
 346 *
 347 * Companion function to spi_alloc_device.  Devices allocated with
 348 * spi_alloc_device can be added onto the spi bus with this function.
 349 *
 350 * Returns 0 on success; negative errno on failure
 351 */
 352int spi_add_device(struct spi_device *spi)
 353{
 354        static DEFINE_MUTEX(spi_add_lock);
 355        struct spi_master *master = spi->master;
 356        struct device *dev = master->dev.parent;
 357        struct device *d;
 358        int status;
 359
 360        /* Chipselects are numbered 0..max; validate. */
 361        if (spi->chip_select >= master->num_chipselect) {
 362                dev_err(dev, "cs%d >= max %d\n",
 363                        spi->chip_select,
 364                        master->num_chipselect);
 365                return -EINVAL;
 366        }
 367
 368        /* Set the bus ID string */
 369        dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
 370                        spi->chip_select);
 371
 372
 373        /* We need to make sure there's no other device with this
 374         * chipselect **BEFORE** we call setup(), else we'll trash
 375         * its configuration.  Lock against concurrent add() calls.
 376         */
 377        mutex_lock(&spi_add_lock);
 378
 379        d = bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));
 380        if (d != NULL) {
 381                dev_err(dev, "chipselect %d already in use\n",
 382                                spi->chip_select);
 383                put_device(d);
 384                status = -EBUSY;
 385                goto done;
 386        }
 387
 388        if (master->cs_gpios)
 389                spi->cs_gpio = master->cs_gpios[spi->chip_select];
 390
 391        /* Drivers may modify this initial i/o setup, but will
 392         * normally rely on the device being setup.  Devices
 393         * using SPI_CS_HIGH can't coexist well otherwise...
 394         */
 395        status = spi_setup(spi);
 396        if (status < 0) {
 397                dev_err(dev, "can't setup %s, status %d\n",
 398                                dev_name(&spi->dev), status);
 399                goto done;
 400        }
 401
 402        /* Device may be bound to an active driver when this returns */
 403        status = device_add(&spi->dev);
 404        if (status < 0)
 405                dev_err(dev, "can't add %s, status %d\n",
 406                                dev_name(&spi->dev), status);
 407        else
 408                dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
 409
 410done:
 411        mutex_unlock(&spi_add_lock);
 412        return status;
 413}
 414EXPORT_SYMBOL_GPL(spi_add_device);
 415
 416/**
 417 * spi_new_device - instantiate one new SPI device
 418 * @master: Controller to which device is connected
 419 * @chip: Describes the SPI device
 420 * Context: can sleep
 421 *
 422 * On typical mainboards, this is purely internal; and it's not needed
 423 * after board init creates the hard-wired devices.  Some development
 424 * platforms may not be able to use spi_register_board_info though, and
 425 * this is exported so that for example a USB or parport based adapter
 426 * driver could add devices (which it would learn about out-of-band).
 427 *
 428 * Returns the new device, or NULL.
 429 */
 430struct spi_device *spi_new_device(struct spi_master *master,
 431                                  struct spi_board_info *chip)
 432{
 433        struct spi_device       *proxy;
 434        int                     status;
 435
 436        /* NOTE:  caller did any chip->bus_num checks necessary.
 437         *
 438         * Also, unless we change the return value convention to use
 439         * error-or-pointer (not NULL-or-pointer), troubleshootability
 440         * suggests syslogged diagnostics are best here (ugh).
 441         */
 442
 443        proxy = spi_alloc_device(master);
 444        if (!proxy)
 445                return NULL;
 446
 447        WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
 448
 449        proxy->chip_select = chip->chip_select;
 450        proxy->max_speed_hz = chip->max_speed_hz;
 451        proxy->mode = chip->mode;
 452        proxy->irq = chip->irq;
 453        strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
 454        proxy->dev.platform_data = (void *) chip->platform_data;
 455        proxy->controller_data = chip->controller_data;
 456        proxy->controller_state = NULL;
 457
 458        status = spi_add_device(proxy);
 459        if (status < 0) {
 460                spi_dev_put(proxy);
 461                return NULL;
 462        }
 463
 464        return proxy;
 465}
 466EXPORT_SYMBOL_GPL(spi_new_device);
 467
 468static void spi_match_master_to_boardinfo(struct spi_master *master,
 469                                struct spi_board_info *bi)
 470{
 471        struct spi_device *dev;
 472
 473        if (master->bus_num != bi->bus_num)
 474                return;
 475
 476        dev = spi_new_device(master, bi);
 477        if (!dev)
 478                dev_err(master->dev.parent, "can't create new device for %s\n",
 479                        bi->modalias);
 480}
 481
 482/**
 483 * spi_register_board_info - register SPI devices for a given board
 484 * @info: array of chip descriptors
 485 * @n: how many descriptors are provided
 486 * Context: can sleep
 487 *
 488 * Board-specific early init code calls this (probably during arch_initcall)
 489 * with segments of the SPI device table.  Any device nodes are created later,
 490 * after the relevant parent SPI controller (bus_num) is defined.  We keep
 491 * this table of devices forever, so that reloading a controller driver will
 492 * not make Linux forget about these hard-wired devices.
 493 *
 494 * Other code can also call this, e.g. a particular add-on board might provide
 495 * SPI devices through its expansion connector, so code initializing that board
 496 * would naturally declare its SPI devices.
 497 *
 498 * The board info passed can safely be __initdata ... but be careful of
 499 * any embedded pointers (platform_data, etc), they're copied as-is.
 500 */
 501int spi_register_board_info(struct spi_board_info const *info, unsigned n)
 502{
 503        struct boardinfo *bi;
 504        int i;
 505
 506        bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
 507        if (!bi)
 508                return -ENOMEM;
 509
 510        for (i = 0; i < n; i++, bi++, info++) {
 511                struct spi_master *master;
 512
 513                memcpy(&bi->board_info, info, sizeof(*info));
 514                mutex_lock(&board_lock);
 515                list_add_tail(&bi->list, &board_list);
 516                list_for_each_entry(master, &spi_master_list, list)
 517                        spi_match_master_to_boardinfo(master, &bi->board_info);
 518                mutex_unlock(&board_lock);
 519        }
 520
 521        return 0;
 522}
 523
 524/*-------------------------------------------------------------------------*/
 525
 526/**
 527 * spi_pump_messages - kthread work function which processes spi message queue
 528 * @work: pointer to kthread work struct contained in the master struct
 529 *
 530 * This function checks if there is any spi message in the queue that
 531 * needs processing and if so call out to the driver to initialize hardware
 532 * and transfer each message.
 533 *
 534 */
 535static void spi_pump_messages(struct kthread_work *work)
 536{
 537        struct spi_master *master =
 538                container_of(work, struct spi_master, pump_messages);
 539        unsigned long flags;
 540        bool was_busy = false;
 541        int ret;
 542
 543        /* Lock queue and check for queue work */
 544        spin_lock_irqsave(&master->queue_lock, flags);
 545        if (list_empty(&master->queue) || !master->running) {
 546                if (!master->busy) {
 547                        spin_unlock_irqrestore(&master->queue_lock, flags);
 548                        return;
 549                }
 550                master->busy = false;
 551                spin_unlock_irqrestore(&master->queue_lock, flags);
 552                if (master->unprepare_transfer_hardware &&
 553                    master->unprepare_transfer_hardware(master))
 554                        dev_err(&master->dev,
 555                                "failed to unprepare transfer hardware\n");
 556                return;
 557        }
 558
 559        /* Make sure we are not already running a message */
 560        if (master->cur_msg) {
 561                spin_unlock_irqrestore(&master->queue_lock, flags);
 562                return;
 563        }
 564        /* Extract head of queue */
 565        master->cur_msg =
 566            list_entry(master->queue.next, struct spi_message, queue);
 567
 568        list_del_init(&master->cur_msg->queue);
 569        if (master->busy)
 570                was_busy = true;
 571        else
 572                master->busy = true;
 573        spin_unlock_irqrestore(&master->queue_lock, flags);
 574
 575        if (!was_busy && master->prepare_transfer_hardware) {
 576                ret = master->prepare_transfer_hardware(master);
 577                if (ret) {
 578                        dev_err(&master->dev,
 579                                "failed to prepare transfer hardware\n");
 580                        return;
 581                }
 582        }
 583
 584        ret = master->transfer_one_message(master, master->cur_msg);
 585        if (ret) {
 586                dev_err(&master->dev,
 587                        "failed to transfer one message from queue\n");
 588                return;
 589        }
 590}
 591
 592static int spi_init_queue(struct spi_master *master)
 593{
 594        struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
 595
 596        INIT_LIST_HEAD(&master->queue);
 597        spin_lock_init(&master->queue_lock);
 598
 599        master->running = false;
 600        master->busy = false;
 601
 602        init_kthread_worker(&master->kworker);
 603        master->kworker_task = kthread_run(kthread_worker_fn,
 604                                           &master->kworker,
 605                                           dev_name(&master->dev));
 606        if (IS_ERR(master->kworker_task)) {
 607                dev_err(&master->dev, "failed to create message pump task\n");
 608                return -ENOMEM;
 609        }
 610        init_kthread_work(&master->pump_messages, spi_pump_messages);
 611
 612        /*
 613         * Master config will indicate if this controller should run the
 614         * message pump with high (realtime) priority to reduce the transfer
 615         * latency on the bus by minimising the delay between a transfer
 616         * request and the scheduling of the message pump thread. Without this
 617         * setting the message pump thread will remain at default priority.
 618         */
 619        if (master->rt) {
 620                dev_info(&master->dev,
 621                        "will run message pump with realtime priority\n");
 622                sched_setscheduler(master->kworker_task, SCHED_FIFO, &param);
 623        }
 624
 625        return 0;
 626}
 627
 628/**
 629 * spi_get_next_queued_message() - called by driver to check for queued
 630 * messages
 631 * @master: the master to check for queued messages
 632 *
 633 * If there are more messages in the queue, the next message is returned from
 634 * this call.
 635 */
 636struct spi_message *spi_get_next_queued_message(struct spi_master *master)
 637{
 638        struct spi_message *next;
 639        unsigned long flags;
 640
 641        /* get a pointer to the next message, if any */
 642        spin_lock_irqsave(&master->queue_lock, flags);
 643        if (list_empty(&master->queue))
 644                next = NULL;
 645        else
 646                next = list_entry(master->queue.next,
 647                                  struct spi_message, queue);
 648        spin_unlock_irqrestore(&master->queue_lock, flags);
 649
 650        return next;
 651}
 652EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
 653
 654/**
 655 * spi_finalize_current_message() - the current message is complete
 656 * @master: the master to return the message to
 657 *
 658 * Called by the driver to notify the core that the message in the front of the
 659 * queue is complete and can be removed from the queue.
 660 */
 661void spi_finalize_current_message(struct spi_master *master)
 662{
 663        struct spi_message *mesg;
 664        unsigned long flags;
 665
 666        spin_lock_irqsave(&master->queue_lock, flags);
 667        mesg = master->cur_msg;
 668        master->cur_msg = NULL;
 669
 670        queue_kthread_work(&master->kworker, &master->pump_messages);
 671        spin_unlock_irqrestore(&master->queue_lock, flags);
 672
 673        mesg->state = NULL;
 674        if (mesg->complete)
 675                mesg->complete(mesg->context);
 676}
 677EXPORT_SYMBOL_GPL(spi_finalize_current_message);
 678
 679static int spi_start_queue(struct spi_master *master)
 680{
 681        unsigned long flags;
 682
 683        spin_lock_irqsave(&master->queue_lock, flags);
 684
 685        if (master->running || master->busy) {
 686                spin_unlock_irqrestore(&master->queue_lock, flags);
 687                return -EBUSY;
 688        }
 689
 690        master->running = true;
 691        master->cur_msg = NULL;
 692        spin_unlock_irqrestore(&master->queue_lock, flags);
 693
 694        queue_kthread_work(&master->kworker, &master->pump_messages);
 695
 696        return 0;
 697}
 698
 699static int spi_stop_queue(struct spi_master *master)
 700{
 701        unsigned long flags;
 702        unsigned limit = 500;
 703        int ret = 0;
 704
 705        spin_lock_irqsave(&master->queue_lock, flags);
 706
 707        /*
 708         * This is a bit lame, but is optimized for the common execution path.
 709         * A wait_queue on the master->busy could be used, but then the common
 710         * execution path (pump_messages) would be required to call wake_up or
 711         * friends on every SPI message. Do this instead.
 712         */
 713        while ((!list_empty(&master->queue) || master->busy) && limit--) {
 714                spin_unlock_irqrestore(&master->queue_lock, flags);
 715                msleep(10);
 716                spin_lock_irqsave(&master->queue_lock, flags);
 717        }
 718
 719        if (!list_empty(&master->queue) || master->busy)
 720                ret = -EBUSY;
 721        else
 722                master->running = false;
 723
 724        spin_unlock_irqrestore(&master->queue_lock, flags);
 725
 726        if (ret) {
 727                dev_warn(&master->dev,
 728                         "could not stop message queue\n");
 729                return ret;
 730        }
 731        return ret;
 732}
 733
 734static int spi_destroy_queue(struct spi_master *master)
 735{
 736        int ret;
 737
 738        ret = spi_stop_queue(master);
 739
 740        /*
 741         * flush_kthread_worker will block until all work is done.
 742         * If the reason that stop_queue timed out is that the work will never
 743         * finish, then it does no good to call flush/stop thread, so
 744         * return anyway.
 745         */
 746        if (ret) {
 747                dev_err(&master->dev, "problem destroying queue\n");
 748                return ret;
 749        }
 750
 751        flush_kthread_worker(&master->kworker);
 752        kthread_stop(master->kworker_task);
 753
 754        return 0;
 755}
 756
 757/**
 758 * spi_queued_transfer - transfer function for queued transfers
 759 * @spi: spi device which is requesting transfer
 760 * @msg: spi message which is to handled is queued to driver queue
 761 */
 762static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
 763{
 764        struct spi_master *master = spi->master;
 765        unsigned long flags;
 766
 767        spin_lock_irqsave(&master->queue_lock, flags);
 768
 769        if (!master->running) {
 770                spin_unlock_irqrestore(&master->queue_lock, flags);
 771                return -ESHUTDOWN;
 772        }
 773        msg->actual_length = 0;
 774        msg->status = -EINPROGRESS;
 775
 776        list_add_tail(&msg->queue, &master->queue);
 777        if (master->running && !master->busy)
 778                queue_kthread_work(&master->kworker, &master->pump_messages);
 779
 780        spin_unlock_irqrestore(&master->queue_lock, flags);
 781        return 0;
 782}
 783
 784static int spi_master_initialize_queue(struct spi_master *master)
 785{
 786        int ret;
 787
 788        master->queued = true;
 789        master->transfer = spi_queued_transfer;
 790
 791        /* Initialize and start queue */
 792        ret = spi_init_queue(master);
 793        if (ret) {
 794                dev_err(&master->dev, "problem initializing queue\n");
 795                goto err_init_queue;
 796        }
 797        ret = spi_start_queue(master);
 798        if (ret) {
 799                dev_err(&master->dev, "problem starting queue\n");
 800                goto err_start_queue;
 801        }
 802
 803        return 0;
 804
 805err_start_queue:
 806err_init_queue:
 807        spi_destroy_queue(master);
 808        return ret;
 809}
 810
 811/*-------------------------------------------------------------------------*/
 812
 813#if defined(CONFIG_OF)
 814/**
 815 * of_register_spi_devices() - Register child devices onto the SPI bus
 816 * @master:     Pointer to spi_master device
 817 *
 818 * Registers an spi_device for each child node of master node which has a 'reg'
 819 * property.
 820 */
 821static void of_register_spi_devices(struct spi_master *master)
 822{
 823        struct spi_device *spi;
 824        struct device_node *nc;
 825        const __be32 *prop;
 826        char modalias[SPI_NAME_SIZE + 4];
 827        int rc;
 828        int len;
 829
 830        if (!master->dev.of_node)
 831                return;
 832
 833        for_each_available_child_of_node(master->dev.of_node, nc) {
 834                /* Alloc an spi_device */
 835                spi = spi_alloc_device(master);
 836                if (!spi) {
 837                        dev_err(&master->dev, "spi_device alloc error for %s\n",
 838                                nc->full_name);
 839                        spi_dev_put(spi);
 840                        continue;
 841                }
 842
 843                /* Select device driver */
 844                if (of_modalias_node(nc, spi->modalias,
 845                                     sizeof(spi->modalias)) < 0) {
 846                        dev_err(&master->dev, "cannot find modalias for %s\n",
 847                                nc->full_name);
 848                        spi_dev_put(spi);
 849                        continue;
 850                }
 851
 852                /* Device address */
 853                prop = of_get_property(nc, "reg", &len);
 854                if (!prop || len < sizeof(*prop)) {
 855                        dev_err(&master->dev, "%s has no 'reg' property\n",
 856                                nc->full_name);
 857                        spi_dev_put(spi);
 858                        continue;
 859                }
 860                spi->chip_select = be32_to_cpup(prop);
 861
 862                /* Mode (clock phase/polarity/etc.) */
 863                if (of_find_property(nc, "spi-cpha", NULL))
 864                        spi->mode |= SPI_CPHA;
 865                if (of_find_property(nc, "spi-cpol", NULL))
 866                        spi->mode |= SPI_CPOL;
 867                if (of_find_property(nc, "spi-cs-high", NULL))
 868                        spi->mode |= SPI_CS_HIGH;
 869                if (of_find_property(nc, "spi-3wire", NULL))
 870                        spi->mode |= SPI_3WIRE;
 871
 872                /* Device speed */
 873                prop = of_get_property(nc, "spi-max-frequency", &len);
 874                if (!prop || len < sizeof(*prop)) {
 875                        dev_err(&master->dev, "%s has no 'spi-max-frequency' property\n",
 876                                nc->full_name);
 877                        spi_dev_put(spi);
 878                        continue;
 879                }
 880                spi->max_speed_hz = be32_to_cpup(prop);
 881
 882                /* IRQ */
 883                spi->irq = irq_of_parse_and_map(nc, 0);
 884
 885                /* Store a pointer to the node in the device structure */
 886                of_node_get(nc);
 887                spi->dev.of_node = nc;
 888
 889                /* Register the new device */
 890                snprintf(modalias, sizeof(modalias), "%s%s", SPI_MODULE_PREFIX,
 891                         spi->modalias);
 892                request_module(modalias);
 893                rc = spi_add_device(spi);
 894                if (rc) {
 895                        dev_err(&master->dev, "spi_device register error %s\n",
 896                                nc->full_name);
 897                        spi_dev_put(spi);
 898                }
 899
 900        }
 901}
 902#else
 903static void of_register_spi_devices(struct spi_master *master) { }
 904#endif
 905
 906#ifdef CONFIG_ACPI
 907static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
 908{
 909        struct spi_device *spi = data;
 910
 911        if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
 912                struct acpi_resource_spi_serialbus *sb;
 913
 914                sb = &ares->data.spi_serial_bus;
 915                if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
 916                        spi->chip_select = sb->device_selection;
 917                        spi->max_speed_hz = sb->connection_speed;
 918
 919                        if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
 920                                spi->mode |= SPI_CPHA;
 921                        if (sb->clock_polarity == ACPI_SPI_START_HIGH)
 922                                spi->mode |= SPI_CPOL;
 923                        if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
 924                                spi->mode |= SPI_CS_HIGH;
 925                }
 926        } else if (spi->irq < 0) {
 927                struct resource r;
 928
 929                if (acpi_dev_resource_interrupt(ares, 0, &r))
 930                        spi->irq = r.start;
 931        }
 932
 933        /* Always tell the ACPI core to skip this resource */
 934        return 1;
 935}
 936
 937static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
 938                                       void *data, void **return_value)
 939{
 940        struct spi_master *master = data;
 941        struct list_head resource_list;
 942        struct acpi_device *adev;
 943        struct spi_device *spi;
 944        int ret;
 945
 946        if (acpi_bus_get_device(handle, &adev))
 947                return AE_OK;
 948        if (acpi_bus_get_status(adev) || !adev->status.present)
 949                return AE_OK;
 950
 951        spi = spi_alloc_device(master);
 952        if (!spi) {
 953                dev_err(&master->dev, "failed to allocate SPI device for %s\n",
 954                        dev_name(&adev->dev));
 955                return AE_NO_MEMORY;
 956        }
 957
 958        ACPI_HANDLE_SET(&spi->dev, handle);
 959        spi->irq = -1;
 960
 961        INIT_LIST_HEAD(&resource_list);
 962        ret = acpi_dev_get_resources(adev, &resource_list,
 963                                     acpi_spi_add_resource, spi);
 964        acpi_dev_free_resource_list(&resource_list);
 965
 966        if (ret < 0 || !spi->max_speed_hz) {
 967                spi_dev_put(spi);
 968                return AE_OK;
 969        }
 970
 971        strlcpy(spi->modalias, dev_name(&adev->dev), sizeof(spi->modalias));
 972        if (spi_add_device(spi)) {
 973                dev_err(&master->dev, "failed to add SPI device %s from ACPI\n",
 974                        dev_name(&adev->dev));
 975                spi_dev_put(spi);
 976        }
 977
 978        return AE_OK;
 979}
 980
 981static void acpi_register_spi_devices(struct spi_master *master)
 982{
 983        acpi_status status;
 984        acpi_handle handle;
 985
 986        handle = ACPI_HANDLE(master->dev.parent);
 987        if (!handle)
 988                return;
 989
 990        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
 991                                     acpi_spi_add_device, NULL,
 992                                     master, NULL);
 993        if (ACPI_FAILURE(status))
 994                dev_warn(&master->dev, "failed to enumerate SPI slaves\n");
 995}
 996#else
 997static inline void acpi_register_spi_devices(struct spi_master *master) {}
 998#endif /* CONFIG_ACPI */
 999
1000static void spi_master_release(struct device *dev)
1001{
1002        struct spi_master *master;
1003
1004        master = container_of(dev, struct spi_master, dev);
1005        kfree(master);
1006}
1007
1008static struct class spi_master_class = {
1009        .name           = "spi_master",
1010        .owner          = THIS_MODULE,
1011        .dev_release    = spi_master_release,
1012};
1013
1014
1015
1016/**
1017 * spi_alloc_master - allocate SPI master controller
1018 * @dev: the controller, possibly using the platform_bus
1019 * @size: how much zeroed driver-private data to allocate; the pointer to this
1020 *      memory is in the driver_data field of the returned device,
1021 *      accessible with spi_master_get_devdata().
1022 * Context: can sleep
1023 *
1024 * This call is used only by SPI master controller drivers, which are the
1025 * only ones directly touching chip registers.  It's how they allocate
1026 * an spi_master structure, prior to calling spi_register_master().
1027 *
1028 * This must be called from context that can sleep.  It returns the SPI
1029 * master structure on success, else NULL.
1030 *
1031 * The caller is responsible for assigning the bus number and initializing
1032 * the master's methods before calling spi_register_master(); and (after errors
1033 * adding the device) calling spi_master_put() and kfree() to prevent a memory
1034 * leak.
1035 */
1036struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
1037{
1038        struct spi_master       *master;
1039
1040        if (!dev)
1041                return NULL;
1042
1043        master = kzalloc(size + sizeof *master, GFP_KERNEL);
1044        if (!master)
1045                return NULL;
1046
1047        device_initialize(&master->dev);
1048        master->bus_num = -1;
1049        master->num_chipselect = 1;
1050        master->dev.class = &spi_master_class;
1051        master->dev.parent = get_device(dev);
1052        spi_master_set_devdata(master, &master[1]);
1053
1054        return master;
1055}
1056EXPORT_SYMBOL_GPL(spi_alloc_master);
1057
1058#ifdef CONFIG_OF
1059static int of_spi_register_master(struct spi_master *master)
1060{
1061        int nb, i, *cs;
1062        struct device_node *np = master->dev.of_node;
1063
1064        if (!np)
1065                return 0;
1066
1067        nb = of_gpio_named_count(np, "cs-gpios");
1068        master->num_chipselect = max(nb, (int)master->num_chipselect);
1069
1070        if (nb < 1)
1071                return 0;
1072
1073        cs = devm_kzalloc(&master->dev,
1074                          sizeof(int) * master->num_chipselect,
1075                          GFP_KERNEL);
1076        master->cs_gpios = cs;
1077
1078        if (!master->cs_gpios)
1079                return -ENOMEM;
1080
1081        for (i = 0; i < master->num_chipselect; i++)
1082                cs[i] = -EINVAL;
1083
1084        for (i = 0; i < nb; i++)
1085                cs[i] = of_get_named_gpio(np, "cs-gpios", i);
1086
1087        return 0;
1088}
1089#else
1090static int of_spi_register_master(struct spi_master *master)
1091{
1092        return 0;
1093}
1094#endif
1095
1096/**
1097 * spi_register_master - register SPI master controller
1098 * @master: initialized master, originally from spi_alloc_master()
1099 * Context: can sleep
1100 *
1101 * SPI master controllers connect to their drivers using some non-SPI bus,
1102 * such as the platform bus.  The final stage of probe() in that code
1103 * includes calling spi_register_master() to hook up to this SPI bus glue.
1104 *
1105 * SPI controllers use board specific (often SOC specific) bus numbers,
1106 * and board-specific addressing for SPI devices combines those numbers
1107 * with chip select numbers.  Since SPI does not directly support dynamic
1108 * device identification, boards need configuration tables telling which
1109 * chip is at which address.
1110 *
1111 * This must be called from context that can sleep.  It returns zero on
1112 * success, else a negative error code (dropping the master's refcount).
1113 * After a successful return, the caller is responsible for calling
1114 * spi_unregister_master().
1115 */
1116int spi_register_master(struct spi_master *master)
1117{
1118        static atomic_t         dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
1119        struct device           *dev = master->dev.parent;
1120        struct boardinfo        *bi;
1121        int                     status = -ENODEV;
1122        int                     dynamic = 0;
1123
1124        if (!dev)
1125                return -ENODEV;
1126
1127        status = of_spi_register_master(master);
1128        if (status)
1129                return status;
1130
1131        /* even if it's just one always-selected device, there must
1132         * be at least one chipselect
1133         */
1134        if (master->num_chipselect == 0)
1135                return -EINVAL;
1136
1137        if ((master->bus_num < 0) && master->dev.of_node)
1138                master->bus_num = of_alias_get_id(master->dev.of_node, "spi");
1139
1140        /* convention:  dynamically assigned bus IDs count down from the max */
1141        if (master->bus_num < 0) {
1142                /* FIXME switch to an IDR based scheme, something like
1143                 * I2C now uses, so we can't run out of "dynamic" IDs
1144                 */
1145                master->bus_num = atomic_dec_return(&dyn_bus_id);
1146                dynamic = 1;
1147        }
1148
1149        spin_lock_init(&master->bus_lock_spinlock);
1150        mutex_init(&master->bus_lock_mutex);
1151        master->bus_lock_flag = 0;
1152
1153        /* register the device, then userspace will see it.
1154         * registration fails if the bus ID is in use.
1155         */
1156        dev_set_name(&master->dev, "spi%u", master->bus_num);
1157        status = device_add(&master->dev);
1158        if (status < 0)
1159                goto done;
1160        dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
1161                        dynamic ? " (dynamic)" : "");
1162
1163        /* If we're using a queued driver, start the queue */
1164        if (master->transfer)
1165                dev_info(dev, "master is unqueued, this is deprecated\n");
1166        else {
1167                status = spi_master_initialize_queue(master);
1168                if (status) {
1169                        device_unregister(&master->dev);
1170                        goto done;
1171                }
1172        }
1173
1174        mutex_lock(&board_lock);
1175        list_add_tail(&master->list, &spi_master_list);
1176        list_for_each_entry(bi, &board_list, list)
1177                spi_match_master_to_boardinfo(master, &bi->board_info);
1178        mutex_unlock(&board_lock);
1179
1180        /* Register devices from the device tree and ACPI */
1181        of_register_spi_devices(master);
1182        acpi_register_spi_devices(master);
1183done:
1184        return status;
1185}
1186EXPORT_SYMBOL_GPL(spi_register_master);
1187
1188static int __unregister(struct device *dev, void *null)
1189{
1190        spi_unregister_device(to_spi_device(dev));
1191        return 0;
1192}
1193
1194/**
1195 * spi_unregister_master - unregister SPI master controller
1196 * @master: the master being unregistered
1197 * Context: can sleep
1198 *
1199 * This call is used only by SPI master controller drivers, which are the
1200 * only ones directly touching chip registers.
1201 *
1202 * This must be called from context that can sleep.
1203 */
1204void spi_unregister_master(struct spi_master *master)
1205{
1206        int dummy;
1207
1208        if (master->queued) {
1209                if (spi_destroy_queue(master))
1210                        dev_err(&master->dev, "queue remove failed\n");
1211        }
1212
1213        mutex_lock(&board_lock);
1214        list_del(&master->list);
1215        mutex_unlock(&board_lock);
1216
1217        dummy = device_for_each_child(&master->dev, NULL, __unregister);
1218        device_unregister(&master->dev);
1219}
1220EXPORT_SYMBOL_GPL(spi_unregister_master);
1221
1222int spi_master_suspend(struct spi_master *master)
1223{
1224        int ret;
1225
1226        /* Basically no-ops for non-queued masters */
1227        if (!master->queued)
1228                return 0;
1229
1230        ret = spi_stop_queue(master);
1231        if (ret)
1232                dev_err(&master->dev, "queue stop failed\n");
1233
1234        return ret;
1235}
1236EXPORT_SYMBOL_GPL(spi_master_suspend);
1237
1238int spi_master_resume(struct spi_master *master)
1239{
1240        int ret;
1241
1242        if (!master->queued)
1243                return 0;
1244
1245        ret = spi_start_queue(master);
1246        if (ret)
1247                dev_err(&master->dev, "queue restart failed\n");
1248
1249        return ret;
1250}
1251EXPORT_SYMBOL_GPL(spi_master_resume);
1252
1253static int __spi_master_match(struct device *dev, const void *data)
1254{
1255        struct spi_master *m;
1256        const u16 *bus_num = data;
1257
1258        m = container_of(dev, struct spi_master, dev);
1259        return m->bus_num == *bus_num;
1260}
1261
1262/**
1263 * spi_busnum_to_master - look up master associated with bus_num
1264 * @bus_num: the master's bus number
1265 * Context: can sleep
1266 *
1267 * This call may be used with devices that are registered after
1268 * arch init time.  It returns a refcounted pointer to the relevant
1269 * spi_master (which the caller must release), or NULL if there is
1270 * no such master registered.
1271 */
1272struct spi_master *spi_busnum_to_master(u16 bus_num)
1273{
1274        struct device           *dev;
1275        struct spi_master       *master = NULL;
1276
1277        dev = class_find_device(&spi_master_class, NULL, &bus_num,
1278                                __spi_master_match);
1279        if (dev)
1280                master = container_of(dev, struct spi_master, dev);
1281        /* reference got in class_find_device */
1282        return master;
1283}
1284EXPORT_SYMBOL_GPL(spi_busnum_to_master);
1285
1286
1287/*-------------------------------------------------------------------------*/
1288
1289/* Core methods for SPI master protocol drivers.  Some of the
1290 * other core methods are currently defined as inline functions.
1291 */
1292
1293/**
1294 * spi_setup - setup SPI mode and clock rate
1295 * @spi: the device whose settings are being modified
1296 * Context: can sleep, and no requests are queued to the device
1297 *
1298 * SPI protocol drivers may need to update the transfer mode if the
1299 * device doesn't work with its default.  They may likewise need
1300 * to update clock rates or word sizes from initial values.  This function
1301 * changes those settings, and must be called from a context that can sleep.
1302 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
1303 * effect the next time the device is selected and data is transferred to
1304 * or from it.  When this function returns, the spi device is deselected.
1305 *
1306 * Note that this call will fail if the protocol driver specifies an option
1307 * that the underlying controller or its driver does not support.  For
1308 * example, not all hardware supports wire transfers using nine bit words,
1309 * LSB-first wire encoding, or active-high chipselects.
1310 */
1311int spi_setup(struct spi_device *spi)
1312{
1313        unsigned        bad_bits;
1314        int             status = 0;
1315
1316        /* help drivers fail *cleanly* when they need options
1317         * that aren't supported with their current master
1318         */
1319        bad_bits = spi->mode & ~spi->master->mode_bits;
1320        if (bad_bits) {
1321                dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
1322                        bad_bits);
1323                return -EINVAL;
1324        }
1325
1326        if (!spi->bits_per_word)
1327                spi->bits_per_word = 8;
1328
1329        if (spi->master->setup)
1330                status = spi->master->setup(spi);
1331
1332        dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
1333                                "%u bits/w, %u Hz max --> %d\n",
1334                        (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
1335                        (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
1336                        (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
1337                        (spi->mode & SPI_3WIRE) ? "3wire, " : "",
1338                        (spi->mode & SPI_LOOP) ? "loopback, " : "",
1339                        spi->bits_per_word, spi->max_speed_hz,
1340                        status);
1341
1342        return status;
1343}
1344EXPORT_SYMBOL_GPL(spi_setup);
1345
1346static int __spi_async(struct spi_device *spi, struct spi_message *message)
1347{
1348        struct spi_master *master = spi->master;
1349        struct spi_transfer *xfer;
1350
1351        /* Half-duplex links include original MicroWire, and ones with
1352         * only one data pin like SPI_3WIRE (switches direction) or where
1353         * either MOSI or MISO is missing.  They can also be caused by
1354         * software limitations.
1355         */
1356        if ((master->flags & SPI_MASTER_HALF_DUPLEX)
1357                        || (spi->mode & SPI_3WIRE)) {
1358                unsigned flags = master->flags;
1359
1360                list_for_each_entry(xfer, &message->transfers, transfer_list) {
1361                        if (xfer->rx_buf && xfer->tx_buf)
1362                                return -EINVAL;
1363                        if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
1364                                return -EINVAL;
1365                        if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
1366                                return -EINVAL;
1367                }
1368        }
1369
1370        /**
1371         * Set transfer bits_per_word and max speed as spi device default if
1372         * it is not set for this transfer.
1373         */
1374        list_for_each_entry(xfer, &message->transfers, transfer_list) {
1375                if (!xfer->bits_per_word)
1376                        xfer->bits_per_word = spi->bits_per_word;
1377                if (!xfer->speed_hz)
1378                        xfer->speed_hz = spi->max_speed_hz;
1379        }
1380
1381        message->spi = spi;
1382        message->status = -EINPROGRESS;
1383        return master->transfer(spi, message);
1384}
1385
1386/**
1387 * spi_async - asynchronous SPI transfer
1388 * @spi: device with which data will be exchanged
1389 * @message: describes the data transfers, including completion callback
1390 * Context: any (irqs may be blocked, etc)
1391 *
1392 * This call may be used in_irq and other contexts which can't sleep,
1393 * as well as from task contexts which can sleep.
1394 *
1395 * The completion callback is invoked in a context which can't sleep.
1396 * Before that invocation, the value of message->status is undefined.
1397 * When the callback is issued, message->status holds either zero (to
1398 * indicate complete success) or a negative error code.  After that
1399 * callback returns, the driver which issued the transfer request may
1400 * deallocate the associated memory; it's no longer in use by any SPI
1401 * core or controller driver code.
1402 *
1403 * Note that although all messages to a spi_device are handled in
1404 * FIFO order, messages may go to different devices in other orders.
1405 * Some device might be higher priority, or have various "hard" access
1406 * time requirements, for example.
1407 *
1408 * On detection of any fault during the transfer, processing of
1409 * the entire message is aborted, and the device is deselected.
1410 * Until returning from the associated message completion callback,
1411 * no other spi_message queued to that device will be processed.
1412 * (This rule applies equally to all the synchronous transfer calls,
1413 * which are wrappers around this core asynchronous primitive.)
1414 */
1415int spi_async(struct spi_device *spi, struct spi_message *message)
1416{
1417        struct spi_master *master = spi->master;
1418        int ret;
1419        unsigned long flags;
1420
1421        spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1422
1423        if (master->bus_lock_flag)
1424                ret = -EBUSY;
1425        else
1426                ret = __spi_async(spi, message);
1427
1428        spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1429
1430        return ret;
1431}
1432EXPORT_SYMBOL_GPL(spi_async);
1433
1434/**
1435 * spi_async_locked - version of spi_async with exclusive bus usage
1436 * @spi: device with which data will be exchanged
1437 * @message: describes the data transfers, including completion callback
1438 * Context: any (irqs may be blocked, etc)
1439 *
1440 * This call may be used in_irq and other contexts which can't sleep,
1441 * as well as from task contexts which can sleep.
1442 *
1443 * The completion callback is invoked in a context which can't sleep.
1444 * Before that invocation, the value of message->status is undefined.
1445 * When the callback is issued, message->status holds either zero (to
1446 * indicate complete success) or a negative error code.  After that
1447 * callback returns, the driver which issued the transfer request may
1448 * deallocate the associated memory; it's no longer in use by any SPI
1449 * core or controller driver code.
1450 *
1451 * Note that although all messages to a spi_device are handled in
1452 * FIFO order, messages may go to different devices in other orders.
1453 * Some device might be higher priority, or have various "hard" access
1454 * time requirements, for example.
1455 *
1456 * On detection of any fault during the transfer, processing of
1457 * the entire message is aborted, and the device is deselected.
1458 * Until returning from the associated message completion callback,
1459 * no other spi_message queued to that device will be processed.
1460 * (This rule applies equally to all the synchronous transfer calls,
1461 * which are wrappers around this core asynchronous primitive.)
1462 */
1463int spi_async_locked(struct spi_device *spi, struct spi_message *message)
1464{
1465        struct spi_master *master = spi->master;
1466        int ret;
1467        unsigned long flags;
1468
1469        spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1470
1471        ret = __spi_async(spi, message);
1472
1473        spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1474
1475        return ret;
1476
1477}
1478EXPORT_SYMBOL_GPL(spi_async_locked);
1479
1480
1481/*-------------------------------------------------------------------------*/
1482
1483/* Utility methods for SPI master protocol drivers, layered on
1484 * top of the core.  Some other utility methods are defined as
1485 * inline functions.
1486 */
1487
1488static void spi_complete(void *arg)
1489{
1490        complete(arg);
1491}
1492
1493static int __spi_sync(struct spi_device *spi, struct spi_message *message,
1494                      int bus_locked)
1495{
1496        DECLARE_COMPLETION_ONSTACK(done);
1497        int status;
1498        struct spi_master *master = spi->master;
1499
1500        message->complete = spi_complete;
1501        message->context = &done;
1502
1503        if (!bus_locked)
1504                mutex_lock(&master->bus_lock_mutex);
1505
1506        status = spi_async_locked(spi, message);
1507
1508        if (!bus_locked)
1509                mutex_unlock(&master->bus_lock_mutex);
1510
1511        if (status == 0) {
1512                wait_for_completion(&done);
1513                status = message->status;
1514        }
1515        message->context = NULL;
1516        return status;
1517}
1518
1519/**
1520 * spi_sync - blocking/synchronous SPI data transfers
1521 * @spi: device with which data will be exchanged
1522 * @message: describes the data transfers
1523 * Context: can sleep
1524 *
1525 * This call may only be used from a context that may sleep.  The sleep
1526 * is non-interruptible, and has no timeout.  Low-overhead controller
1527 * drivers may DMA directly into and out of the message buffers.
1528 *
1529 * Note that the SPI device's chip select is active during the message,
1530 * and then is normally disabled between messages.  Drivers for some
1531 * frequently-used devices may want to minimize costs of selecting a chip,
1532 * by leaving it selected in anticipation that the next message will go
1533 * to the same chip.  (That may increase power usage.)
1534 *
1535 * Also, the caller is guaranteeing that the memory associated with the
1536 * message will not be freed before this call returns.
1537 *
1538 * It returns zero on success, else a negative error code.
1539 */
1540int spi_sync(struct spi_device *spi, struct spi_message *message)
1541{
1542        return __spi_sync(spi, message, 0);
1543}
1544EXPORT_SYMBOL_GPL(spi_sync);
1545
1546/**
1547 * spi_sync_locked - version of spi_sync with exclusive bus usage
1548 * @spi: device with which data will be exchanged
1549 * @message: describes the data transfers
1550 * Context: can sleep
1551 *
1552 * This call may only be used from a context that may sleep.  The sleep
1553 * is non-interruptible, and has no timeout.  Low-overhead controller
1554 * drivers may DMA directly into and out of the message buffers.
1555 *
1556 * This call should be used by drivers that require exclusive access to the
1557 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
1558 * be released by a spi_bus_unlock call when the exclusive access is over.
1559 *
1560 * It returns zero on success, else a negative error code.
1561 */
1562int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
1563{
1564        return __spi_sync(spi, message, 1);
1565}
1566EXPORT_SYMBOL_GPL(spi_sync_locked);
1567
1568/**
1569 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
1570 * @master: SPI bus master that should be locked for exclusive bus access
1571 * Context: can sleep
1572 *
1573 * This call may only be used from a context that may sleep.  The sleep
1574 * is non-interruptible, and has no timeout.
1575 *
1576 * This call should be used by drivers that require exclusive access to the
1577 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
1578 * exclusive access is over. Data transfer must be done by spi_sync_locked
1579 * and spi_async_locked calls when the SPI bus lock is held.
1580 *
1581 * It returns zero on success, else a negative error code.
1582 */
1583int spi_bus_lock(struct spi_master *master)
1584{
1585        unsigned long flags;
1586
1587        mutex_lock(&master->bus_lock_mutex);
1588
1589        spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1590        master->bus_lock_flag = 1;
1591        spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1592
1593        /* mutex remains locked until spi_bus_unlock is called */
1594
1595        return 0;
1596}
1597EXPORT_SYMBOL_GPL(spi_bus_lock);
1598
1599/**
1600 * spi_bus_unlock - release the lock for exclusive SPI bus usage
1601 * @master: SPI bus master that was locked for exclusive bus access
1602 * Context: can sleep
1603 *
1604 * This call may only be used from a context that may sleep.  The sleep
1605 * is non-interruptible, and has no timeout.
1606 *
1607 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
1608 * call.
1609 *
1610 * It returns zero on success, else a negative error code.
1611 */
1612int spi_bus_unlock(struct spi_master *master)
1613{
1614        master->bus_lock_flag = 0;
1615
1616        mutex_unlock(&master->bus_lock_mutex);
1617
1618        return 0;
1619}
1620EXPORT_SYMBOL_GPL(spi_bus_unlock);
1621
1622/* portable code must never pass more than 32 bytes */
1623#define SPI_BUFSIZ      max(32,SMP_CACHE_BYTES)
1624
1625static u8       *buf;
1626
1627/**
1628 * spi_write_then_read - SPI synchronous write followed by read
1629 * @spi: device with which data will be exchanged
1630 * @txbuf: data to be written (need not be dma-safe)
1631 * @n_tx: size of txbuf, in bytes
1632 * @rxbuf: buffer into which data will be read (need not be dma-safe)
1633 * @n_rx: size of rxbuf, in bytes
1634 * Context: can sleep
1635 *
1636 * This performs a half duplex MicroWire style transaction with the
1637 * device, sending txbuf and then reading rxbuf.  The return value
1638 * is zero for success, else a negative errno status code.
1639 * This call may only be used from a context that may sleep.
1640 *
1641 * Parameters to this routine are always copied using a small buffer;
1642 * portable code should never use this for more than 32 bytes.
1643 * Performance-sensitive or bulk transfer code should instead use
1644 * spi_{async,sync}() calls with dma-safe buffers.
1645 */
1646int spi_write_then_read(struct spi_device *spi,
1647                const void *txbuf, unsigned n_tx,
1648                void *rxbuf, unsigned n_rx)
1649{
1650        static DEFINE_MUTEX(lock);
1651
1652        int                     status;
1653        struct spi_message      message;
1654        struct spi_transfer     x[2];
1655        u8                      *local_buf;
1656
1657        /* Use preallocated DMA-safe buffer if we can.  We can't avoid
1658         * copying here, (as a pure convenience thing), but we can
1659         * keep heap costs out of the hot path unless someone else is
1660         * using the pre-allocated buffer or the transfer is too large.
1661         */
1662        if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
1663                local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx),
1664                                    GFP_KERNEL | GFP_DMA);
1665                if (!local_buf)
1666                        return -ENOMEM;
1667        } else {
1668                local_buf = buf;
1669        }
1670
1671        spi_message_init(&message);
1672        memset(x, 0, sizeof x);
1673        if (n_tx) {
1674                x[0].len = n_tx;
1675                spi_message_add_tail(&x[0], &message);
1676        }
1677        if (n_rx) {
1678                x[1].len = n_rx;
1679                spi_message_add_tail(&x[1], &message);
1680        }
1681
1682        memcpy(local_buf, txbuf, n_tx);
1683        x[0].tx_buf = local_buf;
1684        x[1].rx_buf = local_buf + n_tx;
1685
1686        /* do the i/o */
1687        status = spi_sync(spi, &message);
1688        if (status == 0)
1689                memcpy(rxbuf, x[1].rx_buf, n_rx);
1690
1691        if (x[0].tx_buf == buf)
1692                mutex_unlock(&lock);
1693        else
1694                kfree(local_buf);
1695
1696        return status;
1697}
1698EXPORT_SYMBOL_GPL(spi_write_then_read);
1699
1700/*-------------------------------------------------------------------------*/
1701
1702static int __init spi_init(void)
1703{
1704        int     status;
1705
1706        buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1707        if (!buf) {
1708                status = -ENOMEM;
1709                goto err0;
1710        }
1711
1712        status = bus_register(&spi_bus_type);
1713        if (status < 0)
1714                goto err1;
1715
1716        status = class_register(&spi_master_class);
1717        if (status < 0)
1718                goto err2;
1719        return 0;
1720
1721err2:
1722        bus_unregister(&spi_bus_type);
1723err1:
1724        kfree(buf);
1725        buf = NULL;
1726err0:
1727        return status;
1728}
1729
1730/* board_info is normally registered in arch_initcall(),
1731 * but even essential drivers wait till later
1732 *
1733 * REVISIT only boardinfo really needs static linking. the rest (device and
1734 * driver registration) _could_ be dynamically linked (modular) ... costs
1735 * include needing to have boardinfo data structures be much more public.
1736 */
1737postcore_initcall(spi_init);
1738
1739
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.