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/of_gpio.h>
  34#include <linux/pm_runtime.h>
  35#include <linux/export.h>
  36#include <linux/sched.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 && master->unprepare_transfer_hardware) {
 547                        ret = master->unprepare_transfer_hardware(master);
 548                        if (ret) {
 549                                spin_unlock_irqrestore(&master->queue_lock, flags);
 550                                dev_err(&master->dev,
 551                                        "failed to unprepare transfer hardware\n");
 552                                return;
 553                        }
 554                }
 555                master->busy = false;
 556                spin_unlock_irqrestore(&master->queue_lock, flags);
 557                return;
 558        }
 559
 560        /* Make sure we are not already running a message */
 561        if (master->cur_msg) {
 562                spin_unlock_irqrestore(&master->queue_lock, flags);
 563                return;
 564        }
 565        /* Extract head of queue */
 566        master->cur_msg =
 567            list_entry(master->queue.next, struct spi_message, queue);
 568
 569        list_del_init(&master->cur_msg->queue);
 570        if (master->busy)
 571                was_busy = true;
 572        else
 573                master->busy = true;
 574        spin_unlock_irqrestore(&master->queue_lock, flags);
 575
 576        if (!was_busy && master->prepare_transfer_hardware) {
 577                ret = master->prepare_transfer_hardware(master);
 578                if (ret) {
 579                        dev_err(&master->dev,
 580                                "failed to prepare transfer hardware\n");
 581                        return;
 582                }
 583        }
 584
 585        ret = master->transfer_one_message(master, master->cur_msg);
 586        if (ret) {
 587                dev_err(&master->dev,
 588                        "failed to transfer one message from queue\n");
 589                return;
 590        }
 591}
 592
 593static int spi_init_queue(struct spi_master *master)
 594{
 595        struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
 596
 597        INIT_LIST_HEAD(&master->queue);
 598        spin_lock_init(&master->queue_lock);
 599
 600        master->running = false;
 601        master->busy = false;
 602
 603        init_kthread_worker(&master->kworker);
 604        master->kworker_task = kthread_run(kthread_worker_fn,
 605                                           &master->kworker,
 606                                           dev_name(&master->dev));
 607        if (IS_ERR(master->kworker_task)) {
 608                dev_err(&master->dev, "failed to create message pump task\n");
 609                return -ENOMEM;
 610        }
 611        init_kthread_work(&master->pump_messages, spi_pump_messages);
 612
 613        /*
 614         * Master config will indicate if this controller should run the
 615         * message pump with high (realtime) priority to reduce the transfer
 616         * latency on the bus by minimising the delay between a transfer
 617         * request and the scheduling of the message pump thread. Without this
 618         * setting the message pump thread will remain at default priority.
 619         */
 620        if (master->rt) {
 621                dev_info(&master->dev,
 622                        "will run message pump with realtime priority\n");
 623                sched_setscheduler(master->kworker_task, SCHED_FIFO, &param);
 624        }
 625
 626        return 0;
 627}
 628
 629/**
 630 * spi_get_next_queued_message() - called by driver to check for queued
 631 * messages
 632 * @master: the master to check for queued messages
 633 *
 634 * If there are more messages in the queue, the next message is returned from
 635 * this call.
 636 */
 637struct spi_message *spi_get_next_queued_message(struct spi_master *master)
 638{
 639        struct spi_message *next;
 640        unsigned long flags;
 641
 642        /* get a pointer to the next message, if any */
 643        spin_lock_irqsave(&master->queue_lock, flags);
 644        if (list_empty(&master->queue))
 645                next = NULL;
 646        else
 647                next = list_entry(master->queue.next,
 648                                  struct spi_message, queue);
 649        spin_unlock_irqrestore(&master->queue_lock, flags);
 650
 651        return next;
 652}
 653EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
 654
 655/**
 656 * spi_finalize_current_message() - the current message is complete
 657 * @master: the master to return the message to
 658 *
 659 * Called by the driver to notify the core that the message in the front of the
 660 * queue is complete and can be removed from the queue.
 661 */
 662void spi_finalize_current_message(struct spi_master *master)
 663{
 664        struct spi_message *mesg;
 665        unsigned long flags;
 666
 667        spin_lock_irqsave(&master->queue_lock, flags);
 668        mesg = master->cur_msg;
 669        master->cur_msg = NULL;
 670
 671        queue_kthread_work(&master->kworker, &master->pump_messages);
 672        spin_unlock_irqrestore(&master->queue_lock, flags);
 673
 674        mesg->state = NULL;
 675        if (mesg->complete)
 676                mesg->complete(mesg->context);
 677}
 678EXPORT_SYMBOL_GPL(spi_finalize_current_message);
 679
 680static int spi_start_queue(struct spi_master *master)
 681{
 682        unsigned long flags;
 683
 684        spin_lock_irqsave(&master->queue_lock, flags);
 685
 686        if (master->running || master->busy) {
 687                spin_unlock_irqrestore(&master->queue_lock, flags);
 688                return -EBUSY;
 689        }
 690
 691        master->running = true;
 692        master->cur_msg = NULL;
 693        spin_unlock_irqrestore(&master->queue_lock, flags);
 694
 695        queue_kthread_work(&master->kworker, &master->pump_messages);
 696
 697        return 0;
 698}
 699
 700static int spi_stop_queue(struct spi_master *master)
 701{
 702        unsigned long flags;
 703        unsigned limit = 500;
 704        int ret = 0;
 705
 706        spin_lock_irqsave(&master->queue_lock, flags);
 707
 708        /*
 709         * This is a bit lame, but is optimized for the common execution path.
 710         * A wait_queue on the master->busy could be used, but then the common
 711         * execution path (pump_messages) would be required to call wake_up or
 712         * friends on every SPI message. Do this instead.
 713         */
 714        while ((!list_empty(&master->queue) || master->busy) && limit--) {
 715                spin_unlock_irqrestore(&master->queue_lock, flags);
 716                msleep(10);
 717                spin_lock_irqsave(&master->queue_lock, flags);
 718        }
 719
 720        if (!list_empty(&master->queue) || master->busy)
 721                ret = -EBUSY;
 722        else
 723                master->running = false;
 724
 725        spin_unlock_irqrestore(&master->queue_lock, flags);
 726
 727        if (ret) {
 728                dev_warn(&master->dev,
 729                         "could not stop message queue\n");
 730                return ret;
 731        }
 732        return ret;
 733}
 734
 735static int spi_destroy_queue(struct spi_master *master)
 736{
 737        int ret;
 738
 739        ret = spi_stop_queue(master);
 740
 741        /*
 742         * flush_kthread_worker will block until all work is done.
 743         * If the reason that stop_queue timed out is that the work will never
 744         * finish, then it does no good to call flush/stop thread, so
 745         * return anyway.
 746         */
 747        if (ret) {
 748                dev_err(&master->dev, "problem destroying queue\n");
 749                return ret;
 750        }
 751
 752        flush_kthread_worker(&master->kworker);
 753        kthread_stop(master->kworker_task);
 754
 755        return 0;
 756}
 757
 758/**
 759 * spi_queued_transfer - transfer function for queued transfers
 760 * @spi: spi device which is requesting transfer
 761 * @msg: spi message which is to handled is queued to driver queue
 762 */
 763static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
 764{
 765        struct spi_master *master = spi->master;
 766        unsigned long flags;
 767
 768        spin_lock_irqsave(&master->queue_lock, flags);
 769
 770        if (!master->running) {
 771                spin_unlock_irqrestore(&master->queue_lock, flags);
 772                return -ESHUTDOWN;
 773        }
 774        msg->actual_length = 0;
 775        msg->status = -EINPROGRESS;
 776
 777        list_add_tail(&msg->queue, &master->queue);
 778        if (master->running && !master->busy)
 779                queue_kthread_work(&master->kworker, &master->pump_messages);
 780
 781        spin_unlock_irqrestore(&master->queue_lock, flags);
 782        return 0;
 783}
 784
 785static int spi_master_initialize_queue(struct spi_master *master)
 786{
 787        int ret;
 788
 789        master->queued = true;
 790        master->transfer = spi_queued_transfer;
 791
 792        /* Initialize and start queue */
 793        ret = spi_init_queue(master);
 794        if (ret) {
 795                dev_err(&master->dev, "problem initializing queue\n");
 796                goto err_init_queue;
 797        }
 798        ret = spi_start_queue(master);
 799        if (ret) {
 800                dev_err(&master->dev, "problem starting queue\n");
 801                goto err_start_queue;
 802        }
 803
 804        return 0;
 805
 806err_start_queue:
 807err_init_queue:
 808        spi_destroy_queue(master);
 809        return ret;
 810}
 811
 812/*-------------------------------------------------------------------------*/
 813
 814#if defined(CONFIG_OF)
 815/**
 816 * of_register_spi_devices() - Register child devices onto the SPI bus
 817 * @master:     Pointer to spi_master device
 818 *
 819 * Registers an spi_device for each child node of master node which has a 'reg'
 820 * property.
 821 */
 822static void of_register_spi_devices(struct spi_master *master)
 823{
 824        struct spi_device *spi;
 825        struct device_node *nc;
 826        const __be32 *prop;
 827        char modalias[SPI_NAME_SIZE + 4];
 828        int rc;
 829        int len;
 830
 831        if (!master->dev.of_node)
 832                return;
 833
 834        for_each_available_child_of_node(master->dev.of_node, nc) {
 835                /* Alloc an spi_device */
 836                spi = spi_alloc_device(master);
 837                if (!spi) {
 838                        dev_err(&master->dev, "spi_device alloc error for %s\n",
 839                                nc->full_name);
 840                        spi_dev_put(spi);
 841                        continue;
 842                }
 843
 844                /* Select device driver */
 845                if (of_modalias_node(nc, spi->modalias,
 846                                     sizeof(spi->modalias)) < 0) {
 847                        dev_err(&master->dev, "cannot find modalias for %s\n",
 848                                nc->full_name);
 849                        spi_dev_put(spi);
 850                        continue;
 851                }
 852
 853                /* Device address */
 854                prop = of_get_property(nc, "reg", &len);
 855                if (!prop || len < sizeof(*prop)) {
 856                        dev_err(&master->dev, "%s has no 'reg' property\n",
 857                                nc->full_name);
 858                        spi_dev_put(spi);
 859                        continue;
 860                }
 861                spi->chip_select = be32_to_cpup(prop);
 862
 863                /* Mode (clock phase/polarity/etc.) */
 864                if (of_find_property(nc, "spi-cpha", NULL))
 865                        spi->mode |= SPI_CPHA;
 866                if (of_find_property(nc, "spi-cpol", NULL))
 867                        spi->mode |= SPI_CPOL;
 868                if (of_find_property(nc, "spi-cs-high", NULL))
 869                        spi->mode |= SPI_CS_HIGH;
 870                if (of_find_property(nc, "spi-3wire", NULL))
 871                        spi->mode |= SPI_3WIRE;
 872
 873                /* Device speed */
 874                prop = of_get_property(nc, "spi-max-frequency", &len);
 875                if (!prop || len < sizeof(*prop)) {
 876                        dev_err(&master->dev, "%s has no 'spi-max-frequency' property\n",
 877                                nc->full_name);
 878                        spi_dev_put(spi);
 879                        continue;
 880                }
 881                spi->max_speed_hz = be32_to_cpup(prop);
 882
 883                /* IRQ */
 884                spi->irq = irq_of_parse_and_map(nc, 0);
 885
 886                /* Store a pointer to the node in the device structure */
 887                of_node_get(nc);
 888                spi->dev.of_node = nc;
 889
 890                /* Register the new device */
 891                snprintf(modalias, sizeof(modalias), "%s%s", SPI_MODULE_PREFIX,
 892                         spi->modalias);
 893                request_module(modalias);
 894                rc = spi_add_device(spi);
 895                if (rc) {
 896                        dev_err(&master->dev, "spi_device register error %s\n",
 897                                nc->full_name);
 898                        spi_dev_put(spi);
 899                }
 900
 901        }
 902}
 903#else
 904static void of_register_spi_devices(struct spi_master *master) { }
 905#endif
 906
 907#ifdef CONFIG_ACPI
 908static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
 909{
 910        struct spi_device *spi = data;
 911
 912        if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
 913                struct acpi_resource_spi_serialbus *sb;
 914
 915                sb = &ares->data.spi_serial_bus;
 916                if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
 917                        spi->chip_select = sb->device_selection;
 918                        spi->max_speed_hz = sb->connection_speed;
 919
 920                        if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
 921                                spi->mode |= SPI_CPHA;
 922                        if (sb->clock_polarity == ACPI_SPI_START_HIGH)
 923                                spi->mode |= SPI_CPOL;
 924                        if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
 925                                spi->mode |= SPI_CS_HIGH;
 926                }
 927        } else if (spi->irq < 0) {
 928                struct resource r;
 929
 930                if (acpi_dev_resource_interrupt(ares, 0, &r))
 931                        spi->irq = r.start;
 932        }
 933
 934        /* Always tell the ACPI core to skip this resource */
 935        return 1;
 936}
 937
 938static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
 939                                       void *data, void **return_value)
 940{
 941        struct spi_master *master = data;
 942        struct list_head resource_list;
 943        struct acpi_device *adev;
 944        struct spi_device *spi;
 945        int ret;
 946
 947        if (acpi_bus_get_device(handle, &adev))
 948                return AE_OK;
 949        if (acpi_bus_get_status(adev) || !adev->status.present)
 950                return AE_OK;
 951
 952        spi = spi_alloc_device(master);
 953        if (!spi) {
 954                dev_err(&master->dev, "failed to allocate SPI device for %s\n",
 955                        dev_name(&adev->dev));
 956                return AE_NO_MEMORY;
 957        }
 958
 959        ACPI_HANDLE_SET(&spi->dev, handle);
 960        spi->irq = -1;
 961
 962        INIT_LIST_HEAD(&resource_list);
 963        ret = acpi_dev_get_resources(adev, &resource_list,
 964                                     acpi_spi_add_resource, spi);
 965        acpi_dev_free_resource_list(&resource_list);
 966
 967        if (ret < 0 || !spi->max_speed_hz) {
 968                spi_dev_put(spi);
 969                return AE_OK;
 970        }
 971
 972        strlcpy(spi->modalias, dev_name(&adev->dev), sizeof(spi->modalias));
 973        if (spi_add_device(spi)) {
 974                dev_err(&master->dev, "failed to add SPI device %s from ACPI\n",
 975                        dev_name(&adev->dev));
 976                spi_dev_put(spi);
 977        }
 978
 979        return AE_OK;
 980}
 981
 982static void acpi_register_spi_devices(struct spi_master *master)
 983{
 984        acpi_status status;
 985        acpi_handle handle;
 986
 987        handle = ACPI_HANDLE(&master->dev);
 988        if (!handle)
 989                return;
 990
 991        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
 992                                     acpi_spi_add_device, NULL,
 993                                     master, NULL);
 994        if (ACPI_FAILURE(status))
 995                dev_warn(&master->dev, "failed to enumerate SPI slaves\n");
 996}
 997#else
 998static inline void acpi_register_spi_devices(struct spi_master *master) {}
 999#endif /* CONFIG_ACPI */
1000
1001static void spi_master_release(struct device *dev)
1002{
1003        struct spi_master *master;
1004
1005        master = container_of(dev, struct spi_master, dev);
1006        kfree(master);
1007}
1008
1009static struct class spi_master_class = {
1010        .name           = "spi_master",
1011        .owner          = THIS_MODULE,
1012        .dev_release    = spi_master_release,
1013};
1014
1015
1016
1017/**
1018 * spi_alloc_master - allocate SPI master controller
1019 * @dev: the controller, possibly using the platform_bus
1020 * @size: how much zeroed driver-private data to allocate; the pointer to this
1021 *      memory is in the driver_data field of the returned device,
1022 *      accessible with spi_master_get_devdata().
1023 * Context: can sleep
1024 *
1025 * This call is used only by SPI master controller drivers, which are the
1026 * only ones directly touching chip registers.  It's how they allocate
1027 * an spi_master structure, prior to calling spi_register_master().
1028 *
1029 * This must be called from context that can sleep.  It returns the SPI
1030 * master structure on success, else NULL.
1031 *
1032 * The caller is responsible for assigning the bus number and initializing
1033 * the master's methods before calling spi_register_master(); and (after errors
1034 * adding the device) calling spi_master_put() and kfree() to prevent a memory
1035 * leak.
1036 */
1037struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
1038{
1039        struct spi_master       *master;
1040
1041        if (!dev)
1042                return NULL;
1043
1044        master = kzalloc(size + sizeof *master, GFP_KERNEL);
1045        if (!master)
1046                return NULL;
1047
1048        device_initialize(&master->dev);
1049        master->bus_num = -1;
1050        master->num_chipselect = 1;
1051        master->dev.class = &spi_master_class;
1052        master->dev.parent = get_device(dev);
1053        spi_master_set_devdata(master, &master[1]);
1054
1055        return master;
1056}
1057EXPORT_SYMBOL_GPL(spi_alloc_master);
1058
1059#ifdef CONFIG_OF
1060static int of_spi_register_master(struct spi_master *master)
1061{
1062        u16 nb;
1063        int i, *cs;
1064        struct device_node *np = master->dev.of_node;
1065
1066        if (!np)
1067                return 0;
1068
1069        nb = of_gpio_named_count(np, "cs-gpios");
1070        master->num_chipselect = max(nb, master->num_chipselect);
1071
1072        if (nb < 1)
1073                return 0;
1074
1075        cs = devm_kzalloc(&master->dev,
1076                          sizeof(int) * master->num_chipselect,
1077                          GFP_KERNEL);
1078        master->cs_gpios = cs;
1079
1080        if (!master->cs_gpios)
1081                return -ENOMEM;
1082
1083        memset(cs, -EINVAL, master->num_chipselect);
1084
1085        for (i = 0; i < nb; i++)
1086                cs[i] = of_get_named_gpio(np, "cs-gpios", i);
1087
1088        return 0;
1089}
1090#else
1091static int of_spi_register_master(struct spi_master *master)
1092{
1093        return 0;
1094}
1095#endif
1096
1097/**
1098 * spi_register_master - register SPI master controller
1099 * @master: initialized master, originally from spi_alloc_master()
1100 * Context: can sleep
1101 *
1102 * SPI master controllers connect to their drivers using some non-SPI bus,
1103 * such as the platform bus.  The final stage of probe() in that code
1104 * includes calling spi_register_master() to hook up to this SPI bus glue.
1105 *
1106 * SPI controllers use board specific (often SOC specific) bus numbers,
1107 * and board-specific addressing for SPI devices combines those numbers
1108 * with chip select numbers.  Since SPI does not directly support dynamic
1109 * device identification, boards need configuration tables telling which
1110 * chip is at which address.
1111 *
1112 * This must be called from context that can sleep.  It returns zero on
1113 * success, else a negative error code (dropping the master's refcount).
1114 * After a successful return, the caller is responsible for calling
1115 * spi_unregister_master().
1116 */
1117int spi_register_master(struct spi_master *master)
1118{
1119        static atomic_t         dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
1120        struct device           *dev = master->dev.parent;
1121        struct boardinfo        *bi;
1122        int                     status = -ENODEV;
1123        int                     dynamic = 0;
1124
1125        if (!dev)
1126                return -ENODEV;
1127
1128        status = of_spi_register_master(master);
1129        if (status)
1130                return status;
1131
1132        /* even if it's just one always-selected device, there must
1133         * be at least one chipselect
1134         */
1135        if (master->num_chipselect == 0)
1136                return -EINVAL;
1137
1138        /* convention:  dynamically assigned bus IDs count down from the max */
1139        if (master->bus_num < 0) {
1140                /* FIXME switch to an IDR based scheme, something like
1141                 * I2C now uses, so we can't run out of "dynamic" IDs
1142                 */
1143                master->bus_num = atomic_dec_return(&dyn_bus_id);
1144                dynamic = 1;
1145        }
1146
1147        spin_lock_init(&master->bus_lock_spinlock);
1148        mutex_init(&master->bus_lock_mutex);
1149        master->bus_lock_flag = 0;
1150
1151        /* register the device, then userspace will see it.
1152         * registration fails if the bus ID is in use.
1153         */
1154        dev_set_name(&master->dev, "spi%u", master->bus_num);
1155        status = device_add(&master->dev);
1156        if (status < 0)
1157                goto done;
1158        dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
1159                        dynamic ? " (dynamic)" : "");
1160
1161        /* If we're using a queued driver, start the queue */
1162        if (master->transfer)
1163                dev_info(dev, "master is unqueued, this is deprecated\n");
1164        else {
1165                status = spi_master_initialize_queue(master);
1166                if (status) {
1167                        device_unregister(&master->dev);
1168                        goto done;
1169                }
1170        }
1171
1172        mutex_lock(&board_lock);
1173        list_add_tail(&master->list, &spi_master_list);
1174        list_for_each_entry(bi, &board_list, list)
1175                spi_match_master_to_boardinfo(master, &bi->board_info);
1176        mutex_unlock(&board_lock);
1177
1178        /* Register devices from the device tree and ACPI */
1179        of_register_spi_devices(master);
1180        acpi_register_spi_devices(master);
1181done:
1182        return status;
1183}
1184EXPORT_SYMBOL_GPL(spi_register_master);
1185
1186static int __unregister(struct device *dev, void *null)
1187{
1188        spi_unregister_device(to_spi_device(dev));
1189        return 0;
1190}
1191
1192/**
1193 * spi_unregister_master - unregister SPI master controller
1194 * @master: the master being unregistered
1195 * Context: can sleep
1196 *
1197 * This call is used only by SPI master controller drivers, which are the
1198 * only ones directly touching chip registers.
1199 *
1200 * This must be called from context that can sleep.
1201 */
1202void spi_unregister_master(struct spi_master *master)
1203{
1204        int dummy;
1205
1206        if (master->queued) {
1207                if (spi_destroy_queue(master))
1208                        dev_err(&master->dev, "queue remove failed\n");
1209        }
1210
1211        mutex_lock(&board_lock);
1212        list_del(&master->list);
1213        mutex_unlock(&board_lock);
1214
1215        dummy = device_for_each_child(&master->dev, NULL, __unregister);
1216        device_unregister(&master->dev);
1217}
1218EXPORT_SYMBOL_GPL(spi_unregister_master);
1219
1220int spi_master_suspend(struct spi_master *master)
1221{
1222        int ret;
1223
1224        /* Basically no-ops for non-queued masters */
1225        if (!master->queued)
1226                return 0;
1227
1228        ret = spi_stop_queue(master);
1229        if (ret)
1230                dev_err(&master->dev, "queue stop failed\n");
1231
1232        return ret;
1233}
1234EXPORT_SYMBOL_GPL(spi_master_suspend);
1235
1236int spi_master_resume(struct spi_master *master)
1237{
1238        int ret;
1239
1240        if (!master->queued)
1241                return 0;
1242
1243        ret = spi_start_queue(master);
1244        if (ret)
1245                dev_err(&master->dev, "queue restart failed\n");
1246
1247        return ret;
1248}
1249EXPORT_SYMBOL_GPL(spi_master_resume);
1250
1251static int __spi_master_match(struct device *dev, void *data)
1252{
1253        struct spi_master *m;
1254        u16 *bus_num = data;
1255
1256        m = container_of(dev, struct spi_master, dev);
1257        return m->bus_num == *bus_num;
1258}
1259
1260/**
1261 * spi_busnum_to_master - look up master associated with bus_num
1262 * @bus_num: the master's bus number
1263 * Context: can sleep
1264 *
1265 * This call may be used with devices that are registered after
1266 * arch init time.  It returns a refcounted pointer to the relevant
1267 * spi_master (which the caller must release), or NULL if there is
1268 * no such master registered.
1269 */
1270struct spi_master *spi_busnum_to_master(u16 bus_num)
1271{
1272        struct device           *dev;
1273        struct spi_master       *master = NULL;
1274
1275        dev = class_find_device(&spi_master_class, NULL, &bus_num,
1276                                __spi_master_match);
1277        if (dev)
1278                master = container_of(dev, struct spi_master, dev);
1279        /* reference got in class_find_device */
1280        return master;
1281}
1282EXPORT_SYMBOL_GPL(spi_busnum_to_master);
1283
1284
1285/*-------------------------------------------------------------------------*/
1286
1287/* Core methods for SPI master protocol drivers.  Some of the
1288 * other core methods are currently defined as inline functions.
1289 */
1290
1291/**
1292 * spi_setup - setup SPI mode and clock rate
1293 * @spi: the device whose settings are being modified
1294 * Context: can sleep, and no requests are queued to the device
1295 *
1296 * SPI protocol drivers may need to update the transfer mode if the
1297 * device doesn't work with its default.  They may likewise need
1298 * to update clock rates or word sizes from initial values.  This function
1299 * changes those settings, and must be called from a context that can sleep.
1300 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
1301 * effect the next time the device is selected and data is transferred to
1302 * or from it.  When this function returns, the spi device is deselected.
1303 *
1304 * Note that this call will fail if the protocol driver specifies an option
1305 * that the underlying controller or its driver does not support.  For
1306 * example, not all hardware supports wire transfers using nine bit words,
1307 * LSB-first wire encoding, or active-high chipselects.
1308 */
1309int spi_setup(struct spi_device *spi)
1310{
1311        unsigned        bad_bits;
1312        int             status = 0;
1313
1314        /* help drivers fail *cleanly* when they need options
1315         * that aren't supported with their current master
1316         */
1317        bad_bits = spi->mode & ~spi->master->mode_bits;
1318        if (bad_bits) {
1319                dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
1320                        bad_bits);
1321                return -EINVAL;
1322        }
1323
1324        if (!spi->bits_per_word)
1325                spi->bits_per_word = 8;
1326
1327        if (spi->master->setup)
1328                status = spi->master->setup(spi);
1329
1330        dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
1331                                "%u bits/w, %u Hz max --> %d\n",
1332                        (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
1333                        (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
1334                        (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
1335                        (spi->mode & SPI_3WIRE) ? "3wire, " : "",
1336                        (spi->mode & SPI_LOOP) ? "loopback, " : "",
1337                        spi->bits_per_word, spi->max_speed_hz,
1338                        status);
1339
1340        return status;
1341}
1342EXPORT_SYMBOL_GPL(spi_setup);
1343
1344static int __spi_async(struct spi_device *spi, struct spi_message *message)
1345{
1346        struct spi_master *master = spi->master;
1347        struct spi_transfer *xfer;
1348
1349        /* Half-duplex links include original MicroWire, and ones with
1350         * only one data pin like SPI_3WIRE (switches direction) or where
1351         * either MOSI or MISO is missing.  They can also be caused by
1352         * software limitations.
1353         */
1354        if ((master->flags & SPI_MASTER_HALF_DUPLEX)
1355                        || (spi->mode & SPI_3WIRE)) {
1356                unsigned flags = master->flags;
1357
1358                list_for_each_entry(xfer, &message->transfers, transfer_list) {
1359                        if (xfer->rx_buf && xfer->tx_buf)
1360                                return -EINVAL;
1361                        if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
1362                                return -EINVAL;
1363                        if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
1364                                return -EINVAL;
1365                }
1366        }
1367
1368        /**
1369         * Set transfer bits_per_word as spi device default if it is not
1370         * set for this transfer.
1371         */
1372        list_for_each_entry(xfer, &message->transfers, transfer_list) {
1373                if (!xfer->bits_per_word)
1374                        xfer->bits_per_word = spi->bits_per_word;
1375        }
1376
1377        message->spi = spi;
1378        message->status = -EINPROGRESS;
1379        return master->transfer(spi, message);
1380}
1381
1382/**
1383 * spi_async - asynchronous SPI transfer
1384 * @spi: device with which data will be exchanged
1385 * @message: describes the data transfers, including completion callback
1386 * Context: any (irqs may be blocked, etc)
1387 *
1388 * This call may be used in_irq and other contexts which can't sleep,
1389 * as well as from task contexts which can sleep.
1390 *
1391 * The completion callback is invoked in a context which can't sleep.
1392 * Before that invocation, the value of message->status is undefined.
1393 * When the callback is issued, message->status holds either zero (to
1394 * indicate complete success) or a negative error code.  After that
1395 * callback returns, the driver which issued the transfer request may
1396 * deallocate the associated memory; it's no longer in use by any SPI
1397 * core or controller driver code.
1398 *
1399 * Note that although all messages to a spi_device are handled in
1400 * FIFO order, messages may go to different devices in other orders.
1401 * Some device might be higher priority, or have various "hard" access
1402 * time requirements, for example.
1403 *
1404 * On detection of any fault during the transfer, processing of
1405 * the entire message is aborted, and the device is deselected.
1406 * Until returning from the associated message completion callback,
1407 * no other spi_message queued to that device will be processed.
1408 * (This rule applies equally to all the synchronous transfer calls,
1409 * which are wrappers around this core asynchronous primitive.)
1410 */
1411int spi_async(struct spi_device *spi, struct spi_message *message)
1412{
1413        struct spi_master *master = spi->master;
1414        int ret;
1415        unsigned long flags;
1416
1417        spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1418
1419        if (master->bus_lock_flag)
1420                ret = -EBUSY;
1421        else
1422                ret = __spi_async(spi, message);
1423
1424        spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1425
1426        return ret;
1427}
1428EXPORT_SYMBOL_GPL(spi_async);
1429
1430/**
1431 * spi_async_locked - version of spi_async with exclusive bus usage
1432 * @spi: device with which data will be exchanged
1433 * @message: describes the data transfers, including completion callback
1434 * Context: any (irqs may be blocked, etc)
1435 *
1436 * This call may be used in_irq and other contexts which can't sleep,
1437 * as well as from task contexts which can sleep.
1438 *
1439 * The completion callback is invoked in a context which can't sleep.
1440 * Before that invocation, the value of message->status is undefined.
1441 * When the callback is issued, message->status holds either zero (to
1442 * indicate complete success) or a negative error code.  After that
1443 * callback returns, the driver which issued the transfer request may
1444 * deallocate the associated memory; it's no longer in use by any SPI
1445 * core or controller driver code.
1446 *
1447 * Note that although all messages to a spi_device are handled in
1448 * FIFO order, messages may go to different devices in other orders.
1449 * Some device might be higher priority, or have various "hard" access
1450 * time requirements, for example.
1451 *
1452 * On detection of any fault during the transfer, processing of
1453 * the entire message is aborted, and the device is deselected.
1454 * Until returning from the associated message completion callback,
1455 * no other spi_message queued to that device will be processed.
1456 * (This rule applies equally to all the synchronous transfer calls,
1457 * which are wrappers around this core asynchronous primitive.)
1458 */
1459int spi_async_locked(struct spi_device *spi, struct spi_message *message)
1460{
1461        struct spi_master *master = spi->master;
1462        int ret;
1463        unsigned long flags;
1464
1465        spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1466
1467        ret = __spi_async(spi, message);
1468
1469        spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1470
1471        return ret;
1472
1473}
1474EXPORT_SYMBOL_GPL(spi_async_locked);
1475
1476
1477/*-------------------------------------------------------------------------*/
1478
1479/* Utility methods for SPI master protocol drivers, layered on
1480 * top of the core.  Some other utility methods are defined as
1481 * inline functions.
1482 */
1483
1484static void spi_complete(void *arg)
1485{
1486        complete(arg);
1487}
1488
1489static int __spi_sync(struct spi_device *spi, struct spi_message *message,
1490                      int bus_locked)
1491{
1492        DECLARE_COMPLETION_ONSTACK(done);
1493        int status;
1494        struct spi_master *master = spi->master;
1495
1496        message->complete = spi_complete;
1497        message->context = &done;
1498
1499        if (!bus_locked)
1500                mutex_lock(&master->bus_lock_mutex);
1501
1502        status = spi_async_locked(spi, message);
1503
1504        if (!bus_locked)
1505                mutex_unlock(&master->bus_lock_mutex);
1506
1507        if (status == 0) {
1508                wait_for_completion(&done);
1509                status = message->status;
1510        }
1511        message->context = NULL;
1512        return status;
1513}
1514
1515/**
1516 * spi_sync - blocking/synchronous SPI data transfers
1517 * @spi: device with which data will be exchanged
1518 * @message: describes the data transfers
1519 * Context: can sleep
1520 *
1521 * This call may only be used from a context that may sleep.  The sleep
1522 * is non-interruptible, and has no timeout.  Low-overhead controller
1523 * drivers may DMA directly into and out of the message buffers.
1524 *
1525 * Note that the SPI device's chip select is active during the message,
1526 * and then is normally disabled between messages.  Drivers for some
1527 * frequently-used devices may want to minimize costs of selecting a chip,
1528 * by leaving it selected in anticipation that the next message will go
1529 * to the same chip.  (That may increase power usage.)
1530 *
1531 * Also, the caller is guaranteeing that the memory associated with the
1532 * message will not be freed before this call returns.
1533 *
1534 * It returns zero on success, else a negative error code.
1535 */
1536int spi_sync(struct spi_device *spi, struct spi_message *message)
1537{
1538        return __spi_sync(spi, message, 0);
1539}
1540EXPORT_SYMBOL_GPL(spi_sync);
1541
1542/**
1543 * spi_sync_locked - version of spi_sync with exclusive bus usage
1544 * @spi: device with which data will be exchanged
1545 * @message: describes the data transfers
1546 * Context: can sleep
1547 *
1548 * This call may only be used from a context that may sleep.  The sleep
1549 * is non-interruptible, and has no timeout.  Low-overhead controller
1550 * drivers may DMA directly into and out of the message buffers.
1551 *
1552 * This call should be used by drivers that require exclusive access to the
1553 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
1554 * be released by a spi_bus_unlock call when the exclusive access is over.
1555 *
1556 * It returns zero on success, else a negative error code.
1557 */
1558int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
1559{
1560        return __spi_sync(spi, message, 1);
1561}
1562EXPORT_SYMBOL_GPL(spi_sync_locked);
1563
1564/**
1565 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
1566 * @master: SPI bus master that should be locked for exclusive bus access
1567 * Context: can sleep
1568 *
1569 * This call may only be used from a context that may sleep.  The sleep
1570 * is non-interruptible, and has no timeout.
1571 *
1572 * This call should be used by drivers that require exclusive access to the
1573 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
1574 * exclusive access is over. Data transfer must be done by spi_sync_locked
1575 * and spi_async_locked calls when the SPI bus lock is held.
1576 *
1577 * It returns zero on success, else a negative error code.
1578 */
1579int spi_bus_lock(struct spi_master *master)
1580{
1581        unsigned long flags;
1582
1583        mutex_lock(&master->bus_lock_mutex);
1584
1585        spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1586        master->bus_lock_flag = 1;
1587        spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1588
1589        /* mutex remains locked until spi_bus_unlock is called */
1590
1591        return 0;
1592}
1593EXPORT_SYMBOL_GPL(spi_bus_lock);
1594
1595/**
1596 * spi_bus_unlock - release the lock for exclusive SPI bus usage
1597 * @master: SPI bus master that was locked for exclusive bus access
1598 * Context: can sleep
1599 *
1600 * This call may only be used from a context that may sleep.  The sleep
1601 * is non-interruptible, and has no timeout.
1602 *
1603 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
1604 * call.
1605 *
1606 * It returns zero on success, else a negative error code.
1607 */
1608int spi_bus_unlock(struct spi_master *master)
1609{
1610        master->bus_lock_flag = 0;
1611
1612        mutex_unlock(&master->bus_lock_mutex);
1613
1614        return 0;
1615}
1616EXPORT_SYMBOL_GPL(spi_bus_unlock);
1617
1618/* portable code must never pass more than 32 bytes */
1619#define SPI_BUFSIZ      max(32,SMP_CACHE_BYTES)
1620
1621static u8       *buf;
1622
1623/**
1624 * spi_write_then_read - SPI synchronous write followed by read
1625 * @spi: device with which data will be exchanged
1626 * @txbuf: data to be written (need not be dma-safe)
1627 * @n_tx: size of txbuf, in bytes
1628 * @rxbuf: buffer into which data will be read (need not be dma-safe)
1629 * @n_rx: size of rxbuf, in bytes
1630 * Context: can sleep
1631 *
1632 * This performs a half duplex MicroWire style transaction with the
1633 * device, sending txbuf and then reading rxbuf.  The return value
1634 * is zero for success, else a negative errno status code.
1635 * This call may only be used from a context that may sleep.
1636 *
1637 * Parameters to this routine are always copied using a small buffer;
1638 * portable code should never use this for more than 32 bytes.
1639 * Performance-sensitive or bulk transfer code should instead use
1640 * spi_{async,sync}() calls with dma-safe buffers.
1641 */
1642int spi_write_then_read(struct spi_device *spi,
1643                const void *txbuf, unsigned n_tx,
1644                void *rxbuf, unsigned n_rx)
1645{
1646        static DEFINE_MUTEX(lock);
1647
1648        int                     status;
1649        struct spi_message      message;
1650        struct spi_transfer     x[2];
1651        u8                      *local_buf;
1652
1653        /* Use preallocated DMA-safe buffer if we can.  We can't avoid
1654         * copying here, (as a pure convenience thing), but we can
1655         * keep heap costs out of the hot path unless someone else is
1656         * using the pre-allocated buffer or the transfer is too large.
1657         */
1658        if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
1659                local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx), GFP_KERNEL);
1660                if (!local_buf)
1661                        return -ENOMEM;
1662        } else {
1663                local_buf = buf;
1664        }
1665
1666        spi_message_init(&message);
1667        memset(x, 0, sizeof x);
1668        if (n_tx) {
1669                x[0].len = n_tx;
1670                spi_message_add_tail(&x[0], &message);
1671        }
1672        if (n_rx) {
1673                x[1].len = n_rx;
1674                spi_message_add_tail(&x[1], &message);
1675        }
1676
1677        memcpy(local_buf, txbuf, n_tx);
1678        x[0].tx_buf = local_buf;
1679        x[1].rx_buf = local_buf + n_tx;
1680
1681        /* do the i/o */
1682        status = spi_sync(spi, &message);
1683        if (status == 0)
1684                memcpy(rxbuf, x[1].rx_buf, n_rx);
1685
1686        if (x[0].tx_buf == buf)
1687                mutex_unlock(&lock);
1688        else
1689                kfree(local_buf);
1690
1691        return status;
1692}
1693EXPORT_SYMBOL_GPL(spi_write_then_read);
1694
1695/*-------------------------------------------------------------------------*/
1696
1697static int __init spi_init(void)
1698{
1699        int     status;
1700
1701        buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1702        if (!buf) {
1703                status = -ENOMEM;
1704                goto err0;
1705        }
1706
1707        status = bus_register(&spi_bus_type);
1708        if (status < 0)
1709                goto err1;
1710
1711        status = class_register(&spi_master_class);
1712        if (status < 0)
1713                goto err2;
1714        return 0;
1715
1716err2:
1717        bus_unregister(&spi_bus_type);
1718err1:
1719        kfree(buf);
1720        buf = NULL;
1721err0:
1722        return status;
1723}
1724
1725/* board_info is normally registered in arch_initcall(),
1726 * but even essential drivers wait till later
1727 *
1728 * REVISIT only boardinfo really needs static linking. the rest (device and
1729 * driver registration) _could_ be dynamically linked (modular) ... costs
1730 * include needing to have boardinfo data structures be much more public.
1731 */
1732postcore_initcall(spi_init);
1733
1734
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