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