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/rt.h>
  37#include <linux/delay.h>
  38#include <linux/kthread.h>
  39#include <linux/ioport.h>
  40#include <linux/acpi.h>
  41
  42static void spidev_release(struct device *dev)
  43{
  44        struct spi_device       *spi = to_spi_device(dev);
  45
  46        /* spi masters may cleanup for released devices */
  47        if (spi->master->cleanup)
  48                spi->master->cleanup(spi);
  49
  50        spi_master_put(spi->master);
  51        kfree(spi);
  52}
  53
  54static ssize_t
  55modalias_show(struct device *dev, struct device_attribute *a, char *buf)
  56{
  57        const struct spi_device *spi = to_spi_device(dev);
  58
  59        return sprintf(buf, "%s%s\n", SPI_MODULE_PREFIX, spi->modalias);
  60}
  61
  62static struct device_attribute spi_dev_attrs[] = {
  63        __ATTR_RO(modalias),
  64        __ATTR_NULL,
  65};
  66
  67/* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
  68 * and the sysfs version makes coldplug work too.
  69 */
  70
  71static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
  72                                                const struct spi_device *sdev)
  73{
  74        while (id->name[0]) {
  75                if (!strcmp(sdev->modalias, id->name))
  76                        return id;
  77                id++;
  78        }
  79        return NULL;
  80}
  81
  82const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
  83{
  84        const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
  85
  86        return spi_match_id(sdrv->id_table, sdev);
  87}
  88EXPORT_SYMBOL_GPL(spi_get_device_id);
  89
  90static int spi_match_device(struct device *dev, struct device_driver *drv)
  91{
  92        const struct spi_device *spi = to_spi_device(dev);
  93        const struct spi_driver *sdrv = to_spi_driver(drv);
  94
  95        /* Attempt an OF style match */
  96        if (of_driver_match_device(dev, drv))
  97                return 1;
  98
  99        /* Then try ACPI */
 100        if (acpi_driver_match_device(dev, drv))
 101                return 1;
 102
 103        if (sdrv->id_table)
 104                return !!spi_match_id(sdrv->id_table, spi);
 105
 106        return strcmp(spi->modalias, drv->name) == 0;
 107}
 108
 109static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
 110{
 111        const struct spi_device         *spi = to_spi_device(dev);
 112
 113        add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
 114        return 0;
 115}
 116
 117#ifdef CONFIG_PM_SLEEP
 118static int spi_legacy_suspend(struct device *dev, pm_message_t message)
 119{
 120        int                     value = 0;
 121        struct spi_driver       *drv = to_spi_driver(dev->driver);
 122
 123        /* suspend will stop irqs and dma; no more i/o */
 124        if (drv) {
 125                if (drv->suspend)
 126                        value = drv->suspend(to_spi_device(dev), message);
 127                else
 128                        dev_dbg(dev, "... can't suspend\n");
 129        }
 130        return value;
 131}
 132
 133static int spi_legacy_resume(struct device *dev)
 134{
 135        int                     value = 0;
 136        struct spi_driver       *drv = to_spi_driver(dev->driver);
 137
 138        /* resume may restart the i/o queue */
 139        if (drv) {
 140                if (drv->resume)
 141                        value = drv->resume(to_spi_device(dev));
 142                else
 143                        dev_dbg(dev, "... can't resume\n");
 144        }
 145        return value;
 146}
 147
 148static int spi_pm_suspend(struct device *dev)
 149{
 150        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 151
 152        if (pm)
 153                return pm_generic_suspend(dev);
 154        else
 155                return spi_legacy_suspend(dev, PMSG_SUSPEND);
 156}
 157
 158static int spi_pm_resume(struct device *dev)
 159{
 160        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 161
 162        if (pm)
 163                return pm_generic_resume(dev);
 164        else
 165                return spi_legacy_resume(dev);
 166}
 167
 168static int spi_pm_freeze(struct device *dev)
 169{
 170        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 171
 172        if (pm)
 173                return pm_generic_freeze(dev);
 174        else
 175                return spi_legacy_suspend(dev, PMSG_FREEZE);
 176}
 177
 178static int spi_pm_thaw(struct device *dev)
 179{
 180        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 181
 182        if (pm)
 183                return pm_generic_thaw(dev);
 184        else
 185                return spi_legacy_resume(dev);
 186}
 187
 188static int spi_pm_poweroff(struct device *dev)
 189{
 190        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 191
 192        if (pm)
 193                return pm_generic_poweroff(dev);
 194        else
 195                return spi_legacy_suspend(dev, PMSG_HIBERNATE);
 196}
 197
 198static int spi_pm_restore(struct device *dev)
 199{
 200        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 201
 202        if (pm)
 203                return pm_generic_restore(dev);
 204        else
 205                return spi_legacy_resume(dev);
 206}
 207#else
 208#define spi_pm_suspend  NULL
 209#define spi_pm_resume   NULL
 210#define spi_pm_freeze   NULL
 211#define spi_pm_thaw     NULL
 212#define spi_pm_poweroff NULL
 213#define spi_pm_restore  NULL
 214#endif
 215
 216static const struct dev_pm_ops spi_pm = {
 217        .suspend = spi_pm_suspend,
 218        .resume = spi_pm_resume,
 219        .freeze = spi_pm_freeze,
 220        .thaw = spi_pm_thaw,
 221        .poweroff = spi_pm_poweroff,
 222        .restore = spi_pm_restore,
 223        SET_RUNTIME_PM_OPS(
 224                pm_generic_runtime_suspend,
 225                pm_generic_runtime_resume,
 226                NULL
 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 = -ENOENT;
 338        device_initialize(&spi->dev);
 339        return spi;
 340}
 341EXPORT_SYMBOL_GPL(spi_alloc_device);
 342
 343/**
 344 * spi_add_device - Add spi_device allocated with spi_alloc_device
 345 * @spi: spi_device to register
 346 *
 347 * Companion function to spi_alloc_device.  Devices allocated with
 348 * spi_alloc_device can be added onto the spi bus with this function.
 349 *
 350 * Returns 0 on success; negative errno on failure
 351 */
 352int spi_add_device(struct spi_device *spi)
 353{
 354        static DEFINE_MUTEX(spi_add_lock);
 355        struct spi_master *master = spi->master;
 356        struct device *dev = master->dev.parent;
 357        struct device *d;
 358        int status;
 359
 360        /* Chipselects are numbered 0..max; validate. */
 361        if (spi->chip_select >= master->num_chipselect) {
 362                dev_err(dev, "cs%d >= max %d\n",
 363                        spi->chip_select,
 364                        master->num_chipselect);
 365                return -EINVAL;
 366        }
 367
 368        /* Set the bus ID string */
 369        dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
 370                        spi->chip_select);
 371
 372
 373        /* We need to make sure there's no other device with this
 374         * chipselect **BEFORE** we call setup(), else we'll trash
 375         * its configuration.  Lock against concurrent add() calls.
 376         */
 377        mutex_lock(&spi_add_lock);
 378
 379        d = bus_find_device_by_name(&spi_bus_type, NULL, dev_name(&spi->dev));
 380        if (d != NULL) {
 381                dev_err(dev, "chipselect %d already in use\n",
 382                                spi->chip_select);
 383                put_device(d);
 384                status = -EBUSY;
 385                goto done;
 386        }
 387
 388        if (master->cs_gpios)
 389                spi->cs_gpio = master->cs_gpios[spi->chip_select];
 390
 391        /* Drivers may modify this initial i/o setup, but will
 392         * normally rely on the device being setup.  Devices
 393         * using SPI_CS_HIGH can't coexist well otherwise...
 394         */
 395        status = spi_setup(spi);
 396        if (status < 0) {
 397                dev_err(dev, "can't setup %s, status %d\n",
 398                                dev_name(&spi->dev), status);
 399                goto done;
 400        }
 401
 402        /* Device may be bound to an active driver when this returns */
 403        status = device_add(&spi->dev);
 404        if (status < 0)
 405                dev_err(dev, "can't add %s, status %d\n",
 406                                dev_name(&spi->dev), status);
 407        else
 408                dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
 409
 410done:
 411        mutex_unlock(&spi_add_lock);
 412        return status;
 413}
 414EXPORT_SYMBOL_GPL(spi_add_device);
 415
 416/**
 417 * spi_new_device - instantiate one new SPI device
 418 * @master: Controller to which device is connected
 419 * @chip: Describes the SPI device
 420 * Context: can sleep
 421 *
 422 * On typical mainboards, this is purely internal; and it's not needed
 423 * after board init creates the hard-wired devices.  Some development
 424 * platforms may not be able to use spi_register_board_info though, and
 425 * this is exported so that for example a USB or parport based adapter
 426 * driver could add devices (which it would learn about out-of-band).
 427 *
 428 * Returns the new device, or NULL.
 429 */
 430struct spi_device *spi_new_device(struct spi_master *master,
 431                                  struct spi_board_info *chip)
 432{
 433        struct spi_device       *proxy;
 434        int                     status;
 435
 436        /* NOTE:  caller did any chip->bus_num checks necessary.
 437         *
 438         * Also, unless we change the return value convention to use
 439         * error-or-pointer (not NULL-or-pointer), troubleshootability
 440         * suggests syslogged diagnostics are best here (ugh).
 441         */
 442
 443        proxy = spi_alloc_device(master);
 444        if (!proxy)
 445                return NULL;
 446
 447        WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
 448
 449        proxy->chip_select = chip->chip_select;
 450        proxy->max_speed_hz = chip->max_speed_hz;
 451        proxy->mode = chip->mode;
 452        proxy->irq = chip->irq;
 453        strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
 454        proxy->dev.platform_data = (void *) chip->platform_data;
 455        proxy->controller_data = chip->controller_data;
 456        proxy->controller_state = NULL;
 457
 458        status = spi_add_device(proxy);
 459        if (status < 0) {
 460                spi_dev_put(proxy);
 461                return NULL;
 462        }
 463
 464        return proxy;
 465}
 466EXPORT_SYMBOL_GPL(spi_new_device);
 467
 468static void spi_match_master_to_boardinfo(struct spi_master *master,
 469                                struct spi_board_info *bi)
 470{
 471        struct spi_device *dev;
 472
 473        if (master->bus_num != bi->bus_num)
 474                return;
 475
 476        dev = spi_new_device(master, bi);
 477        if (!dev)
 478                dev_err(master->dev.parent, "can't create new device for %s\n",
 479                        bi->modalias);
 480}
 481
 482/**
 483 * spi_register_board_info - register SPI devices for a given board
 484 * @info: array of chip descriptors
 485 * @n: how many descriptors are provided
 486 * Context: can sleep
 487 *
 488 * Board-specific early init code calls this (probably during arch_initcall)
 489 * with segments of the SPI device table.  Any device nodes are created later,
 490 * after the relevant parent SPI controller (bus_num) is defined.  We keep
 491 * this table of devices forever, so that reloading a controller driver will
 492 * not make Linux forget about these hard-wired devices.
 493 *
 494 * Other code can also call this, e.g. a particular add-on board might provide
 495 * SPI devices through its expansion connector, so code initializing that board
 496 * would naturally declare its SPI devices.
 497 *
 498 * The board info passed can safely be __initdata ... but be careful of
 499 * any embedded pointers (platform_data, etc), they're copied as-is.
 500 */
 501int spi_register_board_info(struct spi_board_info const *info, unsigned n)
 502{
 503        struct boardinfo *bi;
 504        int i;
 505
 506        bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
 507        if (!bi)
 508                return -ENOMEM;
 509
 510        for (i = 0; i < n; i++, bi++, info++) {
 511                struct spi_master *master;
 512
 513                memcpy(&bi->board_info, info, sizeof(*info));
 514                mutex_lock(&board_lock);
 515                list_add_tail(&bi->list, &board_list);
 516                list_for_each_entry(master, &spi_master_list, list)
 517                        spi_match_master_to_boardinfo(master, &bi->board_info);
 518                mutex_unlock(&board_lock);
 519        }
 520
 521        return 0;
 522}
 523
 524/*-------------------------------------------------------------------------*/
 525
 526/**
 527 * spi_pump_messages - kthread work function which processes spi message queue
 528 * @work: pointer to kthread work struct contained in the master struct
 529 *
 530 * This function checks if there is any spi message in the queue that
 531 * needs processing and if so call out to the driver to initialize hardware
 532 * and transfer each message.
 533 *
 534 */
 535static void spi_pump_messages(struct kthread_work *work)
 536{
 537        struct spi_master *master =
 538                container_of(work, struct spi_master, pump_messages);
 539        unsigned long flags;
 540        bool was_busy = false;
 541        int ret;
 542
 543        /* Lock queue and check for queue work */
 544        spin_lock_irqsave(&master->queue_lock, flags);
 545        if (list_empty(&master->queue) || !master->running) {
 546                if (!master->busy) {
 547                        spin_unlock_irqrestore(&master->queue_lock, flags);
 548                        return;
 549                }
 550                master->busy = false;
 551                spin_unlock_irqrestore(&master->queue_lock, flags);
 552                if (master->unprepare_transfer_hardware &&
 553                    master->unprepare_transfer_hardware(master))
 554                        dev_err(&master->dev,
 555                                "failed to unprepare transfer hardware\n");
 556                if (master->auto_runtime_pm) {
 557                        pm_runtime_mark_last_busy(master->dev.parent);
 558                        pm_runtime_put_autosuspend(master->dev.parent);
 559                }
 560                return;
 561        }
 562
 563        /* Make sure we are not already running a message */
 564        if (master->cur_msg) {
 565                spin_unlock_irqrestore(&master->queue_lock, flags);
 566                return;
 567        }
 568        /* Extract head of queue */
 569        master->cur_msg =
 570            list_entry(master->queue.next, struct spi_message, queue);
 571
 572        list_del_init(&master->cur_msg->queue);
 573        if (master->busy)
 574                was_busy = true;
 575        else
 576                master->busy = true;
 577        spin_unlock_irqrestore(&master->queue_lock, flags);
 578
 579        if (!was_busy && master->auto_runtime_pm) {
 580                ret = pm_runtime_get_sync(master->dev.parent);
 581                if (ret < 0) {
 582                        dev_err(&master->dev, "Failed to power device: %d\n",
 583                                ret);
 584                        return;
 585                }
 586        }
 587
 588        if (!was_busy && master->prepare_transfer_hardware) {
 589                ret = master->prepare_transfer_hardware(master);
 590                if (ret) {
 591                        dev_err(&master->dev,
 592                                "failed to prepare transfer hardware\n");
 593
 594                        if (master->auto_runtime_pm)
 595                                pm_runtime_put(master->dev.parent);
 596                        return;
 597                }
 598        }
 599
 600        ret = master->transfer_one_message(master, master->cur_msg);
 601        if (ret) {
 602                dev_err(&master->dev,
 603                        "failed to transfer one message from queue\n");
 604                return;
 605        }
 606}
 607
 608static int spi_init_queue(struct spi_master *master)
 609{
 610        struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
 611
 612        INIT_LIST_HEAD(&master->queue);
 613        spin_lock_init(&master->queue_lock);
 614
 615        master->running = false;
 616        master->busy = false;
 617
 618        init_kthread_worker(&master->kworker);
 619        master->kworker_task = kthread_run(kthread_worker_fn,
 620                                           &master->kworker, "%s",
 621                                           dev_name(&master->dev));
 622        if (IS_ERR(master->kworker_task)) {
 623                dev_err(&master->dev, "failed to create message pump task\n");
 624                return -ENOMEM;
 625        }
 626        init_kthread_work(&master->pump_messages, spi_pump_messages);
 627
 628        /*
 629         * Master config will indicate if this controller should run the
 630         * message pump with high (realtime) priority to reduce the transfer
 631         * latency on the bus by minimising the delay between a transfer
 632         * request and the scheduling of the message pump thread. Without this
 633         * setting the message pump thread will remain at default priority.
 634         */
 635        if (master->rt) {
 636                dev_info(&master->dev,
 637                        "will run message pump with realtime priority\n");
 638                sched_setscheduler(master->kworker_task, SCHED_FIFO, &param);
 639        }
 640
 641        return 0;
 642}
 643
 644/**
 645 * spi_get_next_queued_message() - called by driver to check for queued
 646 * messages
 647 * @master: the master to check for queued messages
 648 *
 649 * If there are more messages in the queue, the next message is returned from
 650 * this call.
 651 */
 652struct spi_message *spi_get_next_queued_message(struct spi_master *master)
 653{
 654        struct spi_message *next;
 655        unsigned long flags;
 656
 657        /* get a pointer to the next message, if any */
 658        spin_lock_irqsave(&master->queue_lock, flags);
 659        if (list_empty(&master->queue))
 660                next = NULL;
 661        else
 662                next = list_entry(master->queue.next,
 663                                  struct spi_message, queue);
 664        spin_unlock_irqrestore(&master->queue_lock, flags);
 665
 666        return next;
 667}
 668EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
 669
 670/**
 671 * spi_finalize_current_message() - the current message is complete
 672 * @master: the master to return the message to
 673 *
 674 * Called by the driver to notify the core that the message in the front of the
 675 * queue is complete and can be removed from the queue.
 676 */
 677void spi_finalize_current_message(struct spi_master *master)
 678{
 679        struct spi_message *mesg;
 680        unsigned long flags;
 681
 682        spin_lock_irqsave(&master->queue_lock, flags);
 683        mesg = master->cur_msg;
 684        master->cur_msg = NULL;
 685
 686        queue_kthread_work(&master->kworker, &master->pump_messages);
 687        spin_unlock_irqrestore(&master->queue_lock, flags);
 688
 689        mesg->state = NULL;
 690        if (mesg->complete)
 691                mesg->complete(mesg->context);
 692}
 693EXPORT_SYMBOL_GPL(spi_finalize_current_message);
 694
 695static int spi_start_queue(struct spi_master *master)
 696{
 697        unsigned long flags;
 698
 699        spin_lock_irqsave(&master->queue_lock, flags);
 700
 701        if (master->running || master->busy) {
 702                spin_unlock_irqrestore(&master->queue_lock, flags);
 703                return -EBUSY;
 704        }
 705
 706        master->running = true;
 707        master->cur_msg = NULL;
 708        spin_unlock_irqrestore(&master->queue_lock, flags);
 709
 710        queue_kthread_work(&master->kworker, &master->pump_messages);
 711
 712        return 0;
 713}
 714
 715static int spi_stop_queue(struct spi_master *master)
 716{
 717        unsigned long flags;
 718        unsigned limit = 500;
 719        int ret = 0;
 720
 721        spin_lock_irqsave(&master->queue_lock, flags);
 722
 723        /*
 724         * This is a bit lame, but is optimized for the common execution path.
 725         * A wait_queue on the master->busy could be used, but then the common
 726         * execution path (pump_messages) would be required to call wake_up or
 727         * friends on every SPI message. Do this instead.
 728         */
 729        while ((!list_empty(&master->queue) || master->busy) && limit--) {
 730                spin_unlock_irqrestore(&master->queue_lock, flags);
 731                msleep(10);
 732                spin_lock_irqsave(&master->queue_lock, flags);
 733        }
 734
 735        if (!list_empty(&master->queue) || master->busy)
 736                ret = -EBUSY;
 737        else
 738                master->running = false;
 739
 740        spin_unlock_irqrestore(&master->queue_lock, flags);
 741
 742        if (ret) {
 743                dev_warn(&master->dev,
 744                         "could not stop message queue\n");
 745                return ret;
 746        }
 747        return ret;
 748}
 749
 750static int spi_destroy_queue(struct spi_master *master)
 751{
 752        int ret;
 753
 754        ret = spi_stop_queue(master);
 755
 756        /*
 757         * flush_kthread_worker will block until all work is done.
 758         * If the reason that stop_queue timed out is that the work will never
 759         * finish, then it does no good to call flush/stop thread, so
 760         * return anyway.
 761         */
 762        if (ret) {
 763                dev_err(&master->dev, "problem destroying queue\n");
 764                return ret;
 765        }
 766
 767        flush_kthread_worker(&master->kworker);
 768        kthread_stop(master->kworker_task);
 769
 770        return 0;
 771}
 772
 773/**
 774 * spi_queued_transfer - transfer function for queued transfers
 775 * @spi: spi device which is requesting transfer
 776 * @msg: spi message which is to handled is queued to driver queue
 777 */
 778static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
 779{
 780        struct spi_master *master = spi->master;
 781        unsigned long flags;
 782
 783        spin_lock_irqsave(&master->queue_lock, flags);
 784
 785        if (!master->running) {
 786                spin_unlock_irqrestore(&master->queue_lock, flags);
 787                return -ESHUTDOWN;
 788        }
 789        msg->actual_length = 0;
 790        msg->status = -EINPROGRESS;
 791
 792        list_add_tail(&msg->queue, &master->queue);
 793        if (!master->busy)
 794                queue_kthread_work(&master->kworker, &master->pump_messages);
 795
 796        spin_unlock_irqrestore(&master->queue_lock, flags);
 797        return 0;
 798}
 799
 800static int spi_master_initialize_queue(struct spi_master *master)
 801{
 802        int ret;
 803
 804        master->queued = true;
 805        master->transfer = spi_queued_transfer;
 806
 807        /* Initialize and start queue */
 808        ret = spi_init_queue(master);
 809        if (ret) {
 810                dev_err(&master->dev, "problem initializing queue\n");
 811                goto err_init_queue;
 812        }
 813        ret = spi_start_queue(master);
 814        if (ret) {
 815                dev_err(&master->dev, "problem starting queue\n");
 816                goto err_start_queue;
 817        }
 818
 819        return 0;
 820
 821err_start_queue:
 822err_init_queue:
 823        spi_destroy_queue(master);
 824        return ret;
 825}
 826
 827/*-------------------------------------------------------------------------*/
 828
 829#if defined(CONFIG_OF)
 830/**
 831 * of_register_spi_devices() - Register child devices onto the SPI bus
 832 * @master:     Pointer to spi_master device
 833 *
 834 * Registers an spi_device for each child node of master node which has a 'reg'
 835 * property.
 836 */
 837static void of_register_spi_devices(struct spi_master *master)
 838{
 839        struct spi_device *spi;
 840        struct device_node *nc;
 841        const __be32 *prop;
 842        char modalias[SPI_NAME_SIZE + 4];
 843        int rc;
 844        int len;
 845
 846        if (!master->dev.of_node)
 847                return;
 848
 849        for_each_available_child_of_node(master->dev.of_node, nc) {
 850                /* Alloc an spi_device */
 851                spi = spi_alloc_device(master);
 852                if (!spi) {
 853                        dev_err(&master->dev, "spi_device alloc error for %s\n",
 854                                nc->full_name);
 855                        spi_dev_put(spi);
 856                        continue;
 857                }
 858
 859                /* Select device driver */
 860                if (of_modalias_node(nc, spi->modalias,
 861                                     sizeof(spi->modalias)) < 0) {
 862                        dev_err(&master->dev, "cannot find modalias for %s\n",
 863                                nc->full_name);
 864                        spi_dev_put(spi);
 865                        continue;
 866                }
 867
 868                /* Device address */
 869                prop = of_get_property(nc, "reg", &len);
 870                if (!prop || len < sizeof(*prop)) {
 871                        dev_err(&master->dev, "%s has no 'reg' property\n",
 872                                nc->full_name);
 873                        spi_dev_put(spi);
 874                        continue;
 875                }
 876                spi->chip_select = be32_to_cpup(prop);
 877
 878                /* Mode (clock phase/polarity/etc.) */
 879                if (of_find_property(nc, "spi-cpha", NULL))
 880                        spi->mode |= SPI_CPHA;
 881                if (of_find_property(nc, "spi-cpol", NULL))
 882                        spi->mode |= SPI_CPOL;
 883                if (of_find_property(nc, "spi-cs-high", NULL))
 884                        spi->mode |= SPI_CS_HIGH;
 885                if (of_find_property(nc, "spi-3wire", NULL))
 886                        spi->mode |= SPI_3WIRE;
 887
 888                /* Device DUAL/QUAD mode */
 889                prop = of_get_property(nc, "spi-tx-bus-width", &len);
 890                if (prop && len == sizeof(*prop)) {
 891                        switch (be32_to_cpup(prop)) {
 892                        case SPI_NBITS_SINGLE:
 893                                break;
 894                        case SPI_NBITS_DUAL:
 895                                spi->mode |= SPI_TX_DUAL;
 896                                break;
 897                        case SPI_NBITS_QUAD:
 898                                spi->mode |= SPI_TX_QUAD;
 899                                break;
 900                        default:
 901                                dev_err(&master->dev,
 902                                        "spi-tx-bus-width %d not supported\n",
 903                                        be32_to_cpup(prop));
 904                                spi_dev_put(spi);
 905                                continue;
 906                        }
 907                }
 908
 909                prop = of_get_property(nc, "spi-rx-bus-width", &len);
 910                if (prop && len == sizeof(*prop)) {
 911                        switch (be32_to_cpup(prop)) {
 912                        case SPI_NBITS_SINGLE:
 913                                break;
 914                        case SPI_NBITS_DUAL:
 915                                spi->mode |= SPI_RX_DUAL;
 916                                break;
 917                        case SPI_NBITS_QUAD:
 918                                spi->mode |= SPI_RX_QUAD;
 919                                break;
 920                        default:
 921                                dev_err(&master->dev,
 922                                        "spi-rx-bus-width %d not supported\n",
 923                                        be32_to_cpup(prop));
 924                                spi_dev_put(spi);
 925                                continue;
 926                        }
 927                }
 928
 929                /* Device speed */
 930                prop = of_get_property(nc, "spi-max-frequency", &len);
 931                if (!prop || len < sizeof(*prop)) {
 932                        dev_err(&master->dev, "%s has no 'spi-max-frequency' property\n",
 933                                nc->full_name);
 934                        spi_dev_put(spi);
 935                        continue;
 936                }
 937                spi->max_speed_hz = be32_to_cpup(prop);
 938
 939                /* IRQ */
 940                spi->irq = irq_of_parse_and_map(nc, 0);
 941
 942                /* Store a pointer to the node in the device structure */
 943                of_node_get(nc);
 944                spi->dev.of_node = nc;
 945
 946                /* Register the new device */
 947                snprintf(modalias, sizeof(modalias), "%s%s", SPI_MODULE_PREFIX,
 948                         spi->modalias);
 949                request_module(modalias);
 950                rc = spi_add_device(spi);
 951                if (rc) {
 952                        dev_err(&master->dev, "spi_device register error %s\n",
 953                                nc->full_name);
 954                        spi_dev_put(spi);
 955                }
 956
 957        }
 958}
 959#else
 960static void of_register_spi_devices(struct spi_master *master) { }
 961#endif
 962
 963#ifdef CONFIG_ACPI
 964static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
 965{
 966        struct spi_device *spi = data;
 967
 968        if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
 969                struct acpi_resource_spi_serialbus *sb;
 970
 971                sb = &ares->data.spi_serial_bus;
 972                if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
 973                        spi->chip_select = sb->device_selection;
 974                        spi->max_speed_hz = sb->connection_speed;
 975
 976                        if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
 977                                spi->mode |= SPI_CPHA;
 978                        if (sb->clock_polarity == ACPI_SPI_START_HIGH)
 979                                spi->mode |= SPI_CPOL;
 980                        if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
 981                                spi->mode |= SPI_CS_HIGH;
 982                }
 983        } else if (spi->irq < 0) {
 984                struct resource r;
 985
 986                if (acpi_dev_resource_interrupt(ares, 0, &r))
 987                        spi->irq = r.start;
 988        }
 989
 990        /* Always tell the ACPI core to skip this resource */
 991        return 1;
 992}
 993
 994static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
 995                                       void *data, void **return_value)
 996{
 997        struct spi_master *master = data;
 998        struct list_head resource_list;
 999        struct acpi_device *adev;
1000        struct spi_device *spi;
1001        int ret;
1002
1003        if (acpi_bus_get_device(handle, &adev))
1004                return AE_OK;
1005        if (acpi_bus_get_status(adev) || !adev->status.present)
1006                return AE_OK;
1007
1008        spi = spi_alloc_device(master);
1009        if (!spi) {
1010                dev_err(&master->dev, "failed to allocate SPI device for %s\n",
1011                        dev_name(&adev->dev));
1012                return AE_NO_MEMORY;
1013        }
1014
1015        ACPI_HANDLE_SET(&spi->dev, handle);
1016        spi->irq = -1;
1017
1018        INIT_LIST_HEAD(&resource_list);
1019        ret = acpi_dev_get_resources(adev, &resource_list,
1020                                     acpi_spi_add_resource, spi);
1021        acpi_dev_free_resource_list(&resource_list);
1022
1023        if (ret < 0 || !spi->max_speed_hz) {
1024                spi_dev_put(spi);
1025                return AE_OK;
1026        }
1027
1028        strlcpy(spi->modalias, dev_name(&adev->dev), sizeof(spi->modalias));
1029        if (spi_add_device(spi)) {
1030                dev_err(&master->dev, "failed to add SPI device %s from ACPI\n",
1031                        dev_name(&adev->dev));
1032                spi_dev_put(spi);
1033        }
1034
1035        return AE_OK;
1036}
1037
1038static void acpi_register_spi_devices(struct spi_master *master)
1039{
1040        acpi_status status;
1041        acpi_handle handle;
1042
1043        handle = ACPI_HANDLE(master->dev.parent);
1044        if (!handle)
1045                return;
1046
1047        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
1048                                     acpi_spi_add_device, NULL,
1049                                     master, NULL);
1050        if (ACPI_FAILURE(status))
1051                dev_warn(&master->dev, "failed to enumerate SPI slaves\n");
1052}
1053#else
1054static inline void acpi_register_spi_devices(struct spi_master *master) {}
1055#endif /* CONFIG_ACPI */
1056
1057static void spi_master_release(struct device *dev)
1058{
1059        struct spi_master *master;
1060
1061        master = container_of(dev, struct spi_master, dev);
1062        kfree(master);
1063}
1064
1065static struct class spi_master_class = {
1066        .name           = "spi_master",
1067        .owner          = THIS_MODULE,
1068        .dev_release    = spi_master_release,
1069};
1070
1071
1072
1073/**
1074 * spi_alloc_master - allocate SPI master controller
1075 * @dev: the controller, possibly using the platform_bus
1076 * @size: how much zeroed driver-private data to allocate; the pointer to this
1077 *      memory is in the driver_data field of the returned device,
1078 *      accessible with spi_master_get_devdata().
1079 * Context: can sleep
1080 *
1081 * This call is used only by SPI master controller drivers, which are the
1082 * only ones directly touching chip registers.  It's how they allocate
1083 * an spi_master structure, prior to calling spi_register_master().
1084 *
1085 * This must be called from context that can sleep.  It returns the SPI
1086 * master structure on success, else NULL.
1087 *
1088 * The caller is responsible for assigning the bus number and initializing
1089 * the master's methods before calling spi_register_master(); and (after errors
1090 * adding the device) calling spi_master_put() and kfree() to prevent a memory
1091 * leak.
1092 */
1093struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
1094{
1095        struct spi_master       *master;
1096
1097        if (!dev)
1098                return NULL;
1099
1100        master = kzalloc(size + sizeof *master, GFP_KERNEL);
1101        if (!master)
1102                return NULL;
1103
1104        device_initialize(&master->dev);
1105        master->bus_num = -1;
1106        master->num_chipselect = 1;
1107        master->dev.class = &spi_master_class;
1108        master->dev.parent = get_device(dev);
1109        spi_master_set_devdata(master, &master[1]);
1110
1111        return master;
1112}
1113EXPORT_SYMBOL_GPL(spi_alloc_master);
1114
1115#ifdef CONFIG_OF
1116static int of_spi_register_master(struct spi_master *master)
1117{
1118        int nb, i, *cs;
1119        struct device_node *np = master->dev.of_node;
1120
1121        if (!np)
1122                return 0;
1123
1124        nb = of_gpio_named_count(np, "cs-gpios");
1125        master->num_chipselect = max(nb, (int)master->num_chipselect);
1126
1127        /* Return error only for an incorrectly formed cs-gpios property */
1128        if (nb == 0 || nb == -ENOENT)
1129                return 0;
1130        else if (nb < 0)
1131                return nb;
1132
1133        cs = devm_kzalloc(&master->dev,
1134                          sizeof(int) * master->num_chipselect,
1135                          GFP_KERNEL);
1136        master->cs_gpios = cs;
1137
1138        if (!master->cs_gpios)
1139                return -ENOMEM;
1140
1141        for (i = 0; i < master->num_chipselect; i++)
1142                cs[i] = -ENOENT;
1143
1144        for (i = 0; i < nb; i++)
1145                cs[i] = of_get_named_gpio(np, "cs-gpios", i);
1146
1147        return 0;
1148}
1149#else
1150static int of_spi_register_master(struct spi_master *master)
1151{
1152        return 0;
1153}
1154#endif
1155
1156/**
1157 * spi_register_master - register SPI master controller
1158 * @master: initialized master, originally from spi_alloc_master()
1159 * Context: can sleep
1160 *
1161 * SPI master controllers connect to their drivers using some non-SPI bus,
1162 * such as the platform bus.  The final stage of probe() in that code
1163 * includes calling spi_register_master() to hook up to this SPI bus glue.
1164 *
1165 * SPI controllers use board specific (often SOC specific) bus numbers,
1166 * and board-specific addressing for SPI devices combines those numbers
1167 * with chip select numbers.  Since SPI does not directly support dynamic
1168 * device identification, boards need configuration tables telling which
1169 * chip is at which address.
1170 *
1171 * This must be called from context that can sleep.  It returns zero on
1172 * success, else a negative error code (dropping the master's refcount).
1173 * After a successful return, the caller is responsible for calling
1174 * spi_unregister_master().
1175 */
1176int spi_register_master(struct spi_master *master)
1177{
1178        static atomic_t         dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
1179        struct device           *dev = master->dev.parent;
1180        struct boardinfo        *bi;
1181        int                     status = -ENODEV;
1182        int                     dynamic = 0;
1183
1184        if (!dev)
1185                return -ENODEV;
1186
1187        status = of_spi_register_master(master);
1188        if (status)
1189                return status;
1190
1191        /* even if it's just one always-selected device, there must
1192         * be at least one chipselect
1193         */
1194        if (master->num_chipselect == 0)
1195                return -EINVAL;
1196
1197        if ((master->bus_num < 0) && master->dev.of_node)
1198                master->bus_num = of_alias_get_id(master->dev.of_node, "spi");
1199
1200        /* convention:  dynamically assigned bus IDs count down from the max */
1201        if (master->bus_num < 0) {
1202                /* FIXME switch to an IDR based scheme, something like
1203                 * I2C now uses, so we can't run out of "dynamic" IDs
1204                 */
1205                master->bus_num = atomic_dec_return(&dyn_bus_id);
1206                dynamic = 1;
1207        }
1208
1209        spin_lock_init(&master->bus_lock_spinlock);
1210        mutex_init(&master->bus_lock_mutex);
1211        master->bus_lock_flag = 0;
1212
1213        /* register the device, then userspace will see it.
1214         * registration fails if the bus ID is in use.
1215         */
1216        dev_set_name(&master->dev, "spi%u", master->bus_num);
1217        status = device_add(&master->dev);
1218        if (status < 0)
1219                goto done;
1220        dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
1221                        dynamic ? " (dynamic)" : "");
1222
1223        /* If we're using a queued driver, start the queue */
1224        if (master->transfer)
1225                dev_info(dev, "master is unqueued, this is deprecated\n");
1226        else {
1227                status = spi_master_initialize_queue(master);
1228                if (status) {
1229                        device_del(&master->dev);
1230                        goto done;
1231                }
1232        }
1233
1234        mutex_lock(&board_lock);
1235        list_add_tail(&master->list, &spi_master_list);
1236        list_for_each_entry(bi, &board_list, list)
1237                spi_match_master_to_boardinfo(master, &bi->board_info);
1238        mutex_unlock(&board_lock);
1239
1240        /* Register devices from the device tree and ACPI */
1241        of_register_spi_devices(master);
1242        acpi_register_spi_devices(master);
1243done:
1244        return status;
1245}
1246EXPORT_SYMBOL_GPL(spi_register_master);
1247
1248static int __unregister(struct device *dev, void *null)
1249{
1250        spi_unregister_device(to_spi_device(dev));
1251        return 0;
1252}
1253
1254/**
1255 * spi_unregister_master - unregister SPI master controller
1256 * @master: the master being unregistered
1257 * Context: can sleep
1258 *
1259 * This call is used only by SPI master controller drivers, which are the
1260 * only ones directly touching chip registers.
1261 *
1262 * This must be called from context that can sleep.
1263 */
1264void spi_unregister_master(struct spi_master *master)
1265{
1266        int dummy;
1267
1268        if (master->queued) {
1269                if (spi_destroy_queue(master))
1270                        dev_err(&master->dev, "queue remove failed\n");
1271        }
1272
1273        mutex_lock(&board_lock);
1274        list_del(&master->list);
1275        mutex_unlock(&board_lock);
1276
1277        dummy = device_for_each_child(&master->dev, NULL, __unregister);
1278        device_unregister(&master->dev);
1279}
1280EXPORT_SYMBOL_GPL(spi_unregister_master);
1281
1282int spi_master_suspend(struct spi_master *master)
1283{
1284        int ret;
1285
1286        /* Basically no-ops for non-queued masters */
1287        if (!master->queued)
1288                return 0;
1289
1290        ret = spi_stop_queue(master);
1291        if (ret)
1292                dev_err(&master->dev, "queue stop failed\n");
1293
1294        return ret;
1295}
1296EXPORT_SYMBOL_GPL(spi_master_suspend);
1297
1298int spi_master_resume(struct spi_master *master)
1299{
1300        int ret;
1301
1302        if (!master->queued)
1303                return 0;
1304
1305        ret = spi_start_queue(master);
1306        if (ret)
1307                dev_err(&master->dev, "queue restart failed\n");
1308
1309        return ret;
1310}
1311EXPORT_SYMBOL_GPL(spi_master_resume);
1312
1313static int __spi_master_match(struct device *dev, const void *data)
1314{
1315        struct spi_master *m;
1316        const u16 *bus_num = data;
1317
1318        m = container_of(dev, struct spi_master, dev);
1319        return m->bus_num == *bus_num;
1320}
1321
1322/**
1323 * spi_busnum_to_master - look up master associated with bus_num
1324 * @bus_num: the master's bus number
1325 * Context: can sleep
1326 *
1327 * This call may be used with devices that are registered after
1328 * arch init time.  It returns a refcounted pointer to the relevant
1329 * spi_master (which the caller must release), or NULL if there is
1330 * no such master registered.
1331 */
1332struct spi_master *spi_busnum_to_master(u16 bus_num)
1333{
1334        struct device           *dev;
1335        struct spi_master       *master = NULL;
1336
1337        dev = class_find_device(&spi_master_class, NULL, &bus_num,
1338                                __spi_master_match);
1339        if (dev)
1340                master = container_of(dev, struct spi_master, dev);
1341        /* reference got in class_find_device */
1342        return master;
1343}
1344EXPORT_SYMBOL_GPL(spi_busnum_to_master);
1345
1346
1347/*-------------------------------------------------------------------------*/
1348
1349/* Core methods for SPI master protocol drivers.  Some of the
1350 * other core methods are currently defined as inline functions.
1351 */
1352
1353/**
1354 * spi_setup - setup SPI mode and clock rate
1355 * @spi: the device whose settings are being modified
1356 * Context: can sleep, and no requests are queued to the device
1357 *
1358 * SPI protocol drivers may need to update the transfer mode if the
1359 * device doesn't work with its default.  They may likewise need
1360 * to update clock rates or word sizes from initial values.  This function
1361 * changes those settings, and must be called from a context that can sleep.
1362 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
1363 * effect the next time the device is selected and data is transferred to
1364 * or from it.  When this function returns, the spi device is deselected.
1365 *
1366 * Note that this call will fail if the protocol driver specifies an option
1367 * that the underlying controller or its driver does not support.  For
1368 * example, not all hardware supports wire transfers using nine bit words,
1369 * LSB-first wire encoding, or active-high chipselects.
1370 */
1371int spi_setup(struct spi_device *spi)
1372{
1373        unsigned        bad_bits;
1374        int             status = 0;
1375
1376        /* check mode to prevent that DUAL and QUAD set at the same time
1377         */
1378        if (((spi->mode & SPI_TX_DUAL) && (spi->mode & SPI_TX_QUAD)) ||
1379                ((spi->mode & SPI_RX_DUAL) && (spi->mode & SPI_RX_QUAD))) {
1380                dev_err(&spi->dev,
1381                "setup: can not select dual and quad at the same time\n");
1382                return -EINVAL;
1383        }
1384        /* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
1385         */
1386        if ((spi->mode & SPI_3WIRE) && (spi->mode &
1387                (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)))
1388                return -EINVAL;
1389        /* help drivers fail *cleanly* when they need options
1390         * that aren't supported with their current master
1391         */
1392        bad_bits = spi->mode & ~spi->master->mode_bits;
1393        if (bad_bits) {
1394                dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
1395                        bad_bits);
1396                return -EINVAL;
1397        }
1398
1399        if (!spi->bits_per_word)
1400                spi->bits_per_word = 8;
1401
1402        if (spi->master->setup)
1403                status = spi->master->setup(spi);
1404
1405        dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s"
1406                                "%u bits/w, %u Hz max --> %d\n",
1407                        (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
1408                        (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
1409                        (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
1410                        (spi->mode & SPI_3WIRE) ? "3wire, " : "",
1411                        (spi->mode & SPI_LOOP) ? "loopback, " : "",
1412                        spi->bits_per_word, spi->max_speed_hz,
1413                        status);
1414
1415        return status;
1416}
1417EXPORT_SYMBOL_GPL(spi_setup);
1418
1419static int __spi_async(struct spi_device *spi, struct spi_message *message)
1420{
1421        struct spi_master *master = spi->master;
1422        struct spi_transfer *xfer;
1423
1424        if (list_empty(&message->transfers))
1425                return -EINVAL;
1426        if (!message->complete)
1427                return -EINVAL;
1428
1429        /* Half-duplex links include original MicroWire, and ones with
1430         * only one data pin like SPI_3WIRE (switches direction) or where
1431         * either MOSI or MISO is missing.  They can also be caused by
1432         * software limitations.
1433         */
1434        if ((master->flags & SPI_MASTER_HALF_DUPLEX)
1435                        || (spi->mode & SPI_3WIRE)) {
1436                unsigned flags = master->flags;
1437
1438                list_for_each_entry(xfer, &message->transfers, transfer_list) {
1439                        if (xfer->rx_buf && xfer->tx_buf)
1440                                return -EINVAL;
1441                        if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
1442                                return -EINVAL;
1443                        if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
1444                                return -EINVAL;
1445                }
1446        }
1447
1448        /**
1449         * Set transfer bits_per_word and max speed as spi device default if
1450         * it is not set for this transfer.
1451         * Set transfer tx_nbits and rx_nbits as single transfer default
1452         * (SPI_NBITS_SINGLE) if it is not set for this transfer.
1453         */
1454        list_for_each_entry(xfer, &message->transfers, transfer_list) {
1455                message->frame_length += xfer->len;
1456                if (!xfer->bits_per_word)
1457                        xfer->bits_per_word = spi->bits_per_word;
1458                if (!xfer->speed_hz) {
1459                        xfer->speed_hz = spi->max_speed_hz;
1460                        if (master->max_speed_hz &&
1461                            xfer->speed_hz > master->max_speed_hz)
1462                                xfer->speed_hz = master->max_speed_hz;
1463                }
1464
1465                if (master->bits_per_word_mask) {
1466                        /* Only 32 bits fit in the mask */
1467                        if (xfer->bits_per_word > 32)
1468                                return -EINVAL;
1469                        if (!(master->bits_per_word_mask &
1470                                        BIT(xfer->bits_per_word - 1)))
1471                                return -EINVAL;
1472                }
1473
1474                if (xfer->speed_hz && master->min_speed_hz &&
1475                    xfer->speed_hz < master->min_speed_hz)
1476                        return -EINVAL;
1477                if (xfer->speed_hz && master->max_speed_hz &&
1478                    xfer->speed_hz > master->max_speed_hz)
1479                        return -EINVAL;
1480
1481                if (xfer->tx_buf && !xfer->tx_nbits)
1482                        xfer->tx_nbits = SPI_NBITS_SINGLE;
1483                if (xfer->rx_buf && !xfer->rx_nbits)
1484                        xfer->rx_nbits = SPI_NBITS_SINGLE;
1485                /* check transfer tx/rx_nbits:
1486                 * 1. keep the value is not out of single, dual and quad
1487                 * 2. keep tx/rx_nbits is contained by mode in spi_device
1488                 * 3. if SPI_3WIRE, tx/rx_nbits should be in single
1489                 */
1490                if (xfer->tx_buf) {
1491                        if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
1492                                xfer->tx_nbits != SPI_NBITS_DUAL &&
1493                                xfer->tx_nbits != SPI_NBITS_QUAD)
1494                                return -EINVAL;
1495                        if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
1496                                !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
1497                                return -EINVAL;
1498                        if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
1499                                !(spi->mode & SPI_TX_QUAD))
1500                                return -EINVAL;
1501                        if ((spi->mode & SPI_3WIRE) &&
1502                                (xfer->tx_nbits != SPI_NBITS_SINGLE))
1503                                return -EINVAL;
1504                }
1505                /* check transfer rx_nbits */
1506                if (xfer->rx_buf) {
1507                        if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
1508                                xfer->rx_nbits != SPI_NBITS_DUAL &&
1509                                xfer->rx_nbits != SPI_NBITS_QUAD)
1510                                return -EINVAL;
1511                        if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
1512                                !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
1513                                return -EINVAL;
1514                        if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
1515                                !(spi->mode & SPI_RX_QUAD))
1516                                return -EINVAL;
1517                        if ((spi->mode & SPI_3WIRE) &&
1518                                (xfer->rx_nbits != SPI_NBITS_SINGLE))
1519                                return -EINVAL;
1520                }
1521        }
1522
1523        message->spi = spi;
1524        message->status = -EINPROGRESS;
1525        return master->transfer(spi, message);
1526}
1527
1528/**
1529 * spi_async - asynchronous SPI transfer
1530 * @spi: device with which data will be exchanged
1531 * @message: describes the data transfers, including completion callback
1532 * Context: any (irqs may be blocked, etc)
1533 *
1534 * This call may be used in_irq and other contexts which can't sleep,
1535 * as well as from task contexts which can sleep.
1536 *
1537 * The completion callback is invoked in a context which can't sleep.
1538 * Before that invocation, the value of message->status is undefined.
1539 * When the callback is issued, message->status holds either zero (to
1540 * indicate complete success) or a negative error code.  After that
1541 * callback returns, the driver which issued the transfer request may
1542 * deallocate the associated memory; it's no longer in use by any SPI
1543 * core or controller driver code.
1544 *
1545 * Note that although all messages to a spi_device are handled in
1546 * FIFO order, messages may go to different devices in other orders.
1547 * Some device might be higher priority, or have various "hard" access
1548 * time requirements, for example.
1549 *
1550 * On detection of any fault during the transfer, processing of
1551 * the entire message is aborted, and the device is deselected.
1552 * Until returning from the associated message completion callback,
1553 * no other spi_message queued to that device will be processed.
1554 * (This rule applies equally to all the synchronous transfer calls,
1555 * which are wrappers around this core asynchronous primitive.)
1556 */
1557int spi_async(struct spi_device *spi, struct spi_message *message)
1558{
1559        struct spi_master *master = spi->master;
1560        int ret;
1561        unsigned long flags;
1562
1563        spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1564
1565        if (master->bus_lock_flag)
1566                ret = -EBUSY;
1567        else
1568                ret = __spi_async(spi, message);
1569
1570        spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1571
1572        return ret;
1573}
1574EXPORT_SYMBOL_GPL(spi_async);
1575
1576/**
1577 * spi_async_locked - version of spi_async with exclusive bus usage
1578 * @spi: device with which data will be exchanged
1579 * @message: describes the data transfers, including completion callback
1580 * Context: any (irqs may be blocked, etc)
1581 *
1582 * This call may be used in_irq and other contexts which can't sleep,
1583 * as well as from task contexts which can sleep.
1584 *
1585 * The completion callback is invoked in a context which can't sleep.
1586 * Before that invocation, the value of message->status is undefined.
1587 * When the callback is issued, message->status holds either zero (to
1588 * indicate complete success) or a negative error code.  After that
1589 * callback returns, the driver which issued the transfer request may
1590 * deallocate the associated memory; it's no longer in use by any SPI
1591 * core or controller driver code.
1592 *
1593 * Note that although all messages to a spi_device are handled in
1594 * FIFO order, messages may go to different devices in other orders.
1595 * Some device might be higher priority, or have various "hard" access
1596 * time requirements, for example.
1597 *
1598 * On detection of any fault during the transfer, processing of
1599 * the entire message is aborted, and the device is deselected.
1600 * Until returning from the associated message completion callback,
1601 * no other spi_message queued to that device will be processed.
1602 * (This rule applies equally to all the synchronous transfer calls,
1603 * which are wrappers around this core asynchronous primitive.)
1604 */
1605int spi_async_locked(struct spi_device *spi, struct spi_message *message)
1606{
1607        struct spi_master *master = spi->master;
1608        int ret;
1609        unsigned long flags;
1610
1611        spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1612
1613        ret = __spi_async(spi, message);
1614
1615        spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1616
1617        return ret;
1618
1619}
1620EXPORT_SYMBOL_GPL(spi_async_locked);
1621
1622
1623/*-------------------------------------------------------------------------*/
1624
1625/* Utility methods for SPI master protocol drivers, layered on
1626 * top of the core.  Some other utility methods are defined as
1627 * inline functions.
1628 */
1629
1630static void spi_complete(void *arg)
1631{
1632        complete(arg);
1633}
1634
1635static int __spi_sync(struct spi_device *spi, struct spi_message *message,
1636                      int bus_locked)
1637{
1638        DECLARE_COMPLETION_ONSTACK(done);
1639        int status;
1640        struct spi_master *master = spi->master;
1641
1642        message->complete = spi_complete;
1643        message->context = &done;
1644
1645        if (!bus_locked)
1646                mutex_lock(&master->bus_lock_mutex);
1647
1648        status = spi_async_locked(spi, message);
1649
1650        if (!bus_locked)
1651                mutex_unlock(&master->bus_lock_mutex);
1652
1653        if (status == 0) {
1654                wait_for_completion(&done);
1655                status = message->status;
1656        }
1657        message->context = NULL;
1658        return status;
1659}
1660
1661/**
1662 * spi_sync - blocking/synchronous SPI data transfers
1663 * @spi: device with which data will be exchanged
1664 * @message: describes the data transfers
1665 * Context: can sleep
1666 *
1667 * This call may only be used from a context that may sleep.  The sleep
1668 * is non-interruptible, and has no timeout.  Low-overhead controller
1669 * drivers may DMA directly into and out of the message buffers.
1670 *
1671 * Note that the SPI device's chip select is active during the message,
1672 * and then is normally disabled between messages.  Drivers for some
1673 * frequently-used devices may want to minimize costs of selecting a chip,
1674 * by leaving it selected in anticipation that the next message will go
1675 * to the same chip.  (That may increase power usage.)
1676 *
1677 * Also, the caller is guaranteeing that the memory associated with the
1678 * message will not be freed before this call returns.
1679 *
1680 * It returns zero on success, else a negative error code.
1681 */
1682int spi_sync(struct spi_device *spi, struct spi_message *message)
1683{
1684        return __spi_sync(spi, message, 0);
1685}
1686EXPORT_SYMBOL_GPL(spi_sync);
1687
1688/**
1689 * spi_sync_locked - version of spi_sync with exclusive bus usage
1690 * @spi: device with which data will be exchanged
1691 * @message: describes the data transfers
1692 * Context: can sleep
1693 *
1694 * This call may only be used from a context that may sleep.  The sleep
1695 * is non-interruptible, and has no timeout.  Low-overhead controller
1696 * drivers may DMA directly into and out of the message buffers.
1697 *
1698 * This call should be used by drivers that require exclusive access to the
1699 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
1700 * be released by a spi_bus_unlock call when the exclusive access is over.
1701 *
1702 * It returns zero on success, else a negative error code.
1703 */
1704int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
1705{
1706        return __spi_sync(spi, message, 1);
1707}
1708EXPORT_SYMBOL_GPL(spi_sync_locked);
1709
1710/**
1711 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
1712 * @master: SPI bus master that should be locked for exclusive bus access
1713 * Context: can sleep
1714 *
1715 * This call may only be used from a context that may sleep.  The sleep
1716 * is non-interruptible, and has no timeout.
1717 *
1718 * This call should be used by drivers that require exclusive access to the
1719 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
1720 * exclusive access is over. Data transfer must be done by spi_sync_locked
1721 * and spi_async_locked calls when the SPI bus lock is held.
1722 *
1723 * It returns zero on success, else a negative error code.
1724 */
1725int spi_bus_lock(struct spi_master *master)
1726{
1727        unsigned long flags;
1728
1729        mutex_lock(&master->bus_lock_mutex);
1730
1731        spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1732        master->bus_lock_flag = 1;
1733        spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1734
1735        /* mutex remains locked until spi_bus_unlock is called */
1736
1737        return 0;
1738}
1739EXPORT_SYMBOL_GPL(spi_bus_lock);
1740
1741/**
1742 * spi_bus_unlock - release the lock for exclusive SPI bus usage
1743 * @master: SPI bus master that was locked for exclusive bus access
1744 * Context: can sleep
1745 *
1746 * This call may only be used from a context that may sleep.  The sleep
1747 * is non-interruptible, and has no timeout.
1748 *
1749 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
1750 * call.
1751 *
1752 * It returns zero on success, else a negative error code.
1753 */
1754int spi_bus_unlock(struct spi_master *master)
1755{
1756        master->bus_lock_flag = 0;
1757
1758        mutex_unlock(&master->bus_lock_mutex);
1759
1760        return 0;
1761}
1762EXPORT_SYMBOL_GPL(spi_bus_unlock);
1763
1764/* portable code must never pass more than 32 bytes */
1765#define SPI_BUFSIZ      max(32,SMP_CACHE_BYTES)
1766
1767static u8       *buf;
1768
1769/**
1770 * spi_write_then_read - SPI synchronous write followed by read
1771 * @spi: device with which data will be exchanged
1772 * @txbuf: data to be written (need not be dma-safe)
1773 * @n_tx: size of txbuf, in bytes
1774 * @rxbuf: buffer into which data will be read (need not be dma-safe)
1775 * @n_rx: size of rxbuf, in bytes
1776 * Context: can sleep
1777 *
1778 * This performs a half duplex MicroWire style transaction with the
1779 * device, sending txbuf and then reading rxbuf.  The return value
1780 * is zero for success, else a negative errno status code.
1781 * This call may only be used from a context that may sleep.
1782 *
1783 * Parameters to this routine are always copied using a small buffer;
1784 * portable code should never use this for more than 32 bytes.
1785 * Performance-sensitive or bulk transfer code should instead use
1786 * spi_{async,sync}() calls with dma-safe buffers.
1787 */
1788int spi_write_then_read(struct spi_device *spi,
1789                const void *txbuf, unsigned n_tx,
1790                void *rxbuf, unsigned n_rx)
1791{
1792        static DEFINE_MUTEX(lock);
1793
1794        int                     status;
1795        struct spi_message      message;
1796        struct spi_transfer     x[2];
1797        u8                      *local_buf;
1798
1799        /* Use preallocated DMA-safe buffer if we can.  We can't avoid
1800         * copying here, (as a pure convenience thing), but we can
1801         * keep heap costs out of the hot path unless someone else is
1802         * using the pre-allocated buffer or the transfer is too large.
1803         */
1804        if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
1805                local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx),
1806                                    GFP_KERNEL | GFP_DMA);
1807                if (!local_buf)
1808                        return -ENOMEM;
1809        } else {
1810                local_buf = buf;
1811        }
1812
1813        spi_message_init(&message);
1814        memset(x, 0, sizeof x);
1815        if (n_tx) {
1816                x[0].len = n_tx;
1817                spi_message_add_tail(&x[0], &message);
1818        }
1819        if (n_rx) {
1820                x[1].len = n_rx;
1821                spi_message_add_tail(&x[1], &message);
1822        }
1823
1824        memcpy(local_buf, txbuf, n_tx);
1825        x[0].tx_buf = local_buf;
1826        x[1].rx_buf = local_buf + n_tx;
1827
1828        /* do the i/o */
1829        status = spi_sync(spi, &message);
1830        if (status == 0)
1831                memcpy(rxbuf, x[1].rx_buf, n_rx);
1832
1833        if (x[0].tx_buf == buf)
1834                mutex_unlock(&lock);
1835        else
1836                kfree(local_buf);
1837
1838        return status;
1839}
1840EXPORT_SYMBOL_GPL(spi_write_then_read);
1841
1842/*-------------------------------------------------------------------------*/
1843
1844static int __init spi_init(void)
1845{
1846        int     status;
1847
1848        buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
1849        if (!buf) {
1850                status = -ENOMEM;
1851                goto err0;
1852        }
1853
1854        status = bus_register(&spi_bus_type);
1855        if (status < 0)
1856                goto err1;
1857
1858        status = class_register(&spi_master_class);
1859        if (status < 0)
1860                goto err2;
1861        return 0;
1862
1863err2:
1864        bus_unregister(&spi_bus_type);
1865err1:
1866        kfree(buf);
1867        buf = NULL;
1868err0:
1869        return status;
1870}
1871
1872/* board_info is normally registered in arch_initcall(),
1873 * but even essential drivers wait till later
1874 *
1875 * REVISIT only boardinfo really needs static linking. the rest (device and
1876 * driver registration) _could_ be dynamically linked (modular) ... costs
1877 * include needing to have boardinfo data structures be much more public.
1878 */
1879postcore_initcall(spi_init);
1880
1881
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