linux/drivers/hsi/hsi.c
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   1/*
   2 * HSI core.
   3 *
   4 * Copyright (C) 2010 Nokia Corporation. All rights reserved.
   5 *
   6 * Contact: Carlos Chinea <carlos.chinea@nokia.com>
   7 *
   8 * This program is free software; you can redistribute it and/or
   9 * modify it under the terms of the GNU General Public License
  10 * version 2 as published by the Free Software Foundation.
  11 *
  12 * This program is distributed in the hope that it will be useful, but
  13 * WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 * 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., 51 Franklin St, Fifth Floor, Boston, MA
  20 * 02110-1301 USA
  21 */
  22#include <linux/hsi/hsi.h>
  23#include <linux/compiler.h>
  24#include <linux/list.h>
  25#include <linux/kobject.h>
  26#include <linux/slab.h>
  27#include <linux/string.h>
  28#include <linux/notifier.h>
  29#include "hsi_core.h"
  30
  31static ssize_t modalias_show(struct device *dev,
  32                        struct device_attribute *a __maybe_unused, char *buf)
  33{
  34        return sprintf(buf, "hsi:%s\n", dev_name(dev));
  35}
  36
  37static struct device_attribute hsi_bus_dev_attrs[] = {
  38        __ATTR_RO(modalias),
  39        __ATTR_NULL,
  40};
  41
  42static int hsi_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
  43{
  44        add_uevent_var(env, "MODALIAS=hsi:%s", dev_name(dev));
  45
  46        return 0;
  47}
  48
  49static int hsi_bus_match(struct device *dev, struct device_driver *driver)
  50{
  51        return strcmp(dev_name(dev), driver->name) == 0;
  52}
  53
  54static struct bus_type hsi_bus_type = {
  55        .name           = "hsi",
  56        .dev_attrs      = hsi_bus_dev_attrs,
  57        .match          = hsi_bus_match,
  58        .uevent         = hsi_bus_uevent,
  59};
  60
  61static void hsi_client_release(struct device *dev)
  62{
  63        kfree(to_hsi_client(dev));
  64}
  65
  66static void hsi_new_client(struct hsi_port *port, struct hsi_board_info *info)
  67{
  68        struct hsi_client *cl;
  69
  70        cl = kzalloc(sizeof(*cl), GFP_KERNEL);
  71        if (!cl)
  72                return;
  73        cl->tx_cfg = info->tx_cfg;
  74        cl->rx_cfg = info->rx_cfg;
  75        cl->device.bus = &hsi_bus_type;
  76        cl->device.parent = &port->device;
  77        cl->device.release = hsi_client_release;
  78        dev_set_name(&cl->device, info->name);
  79        cl->device.platform_data = info->platform_data;
  80        if (info->archdata)
  81                cl->device.archdata = *info->archdata;
  82        if (device_register(&cl->device) < 0) {
  83                pr_err("hsi: failed to register client: %s\n", info->name);
  84                put_device(&cl->device);
  85        }
  86}
  87
  88static void hsi_scan_board_info(struct hsi_controller *hsi)
  89{
  90        struct hsi_cl_info *cl_info;
  91        struct hsi_port *p;
  92
  93        list_for_each_entry(cl_info, &hsi_board_list, list)
  94                if (cl_info->info.hsi_id == hsi->id) {
  95                        p = hsi_find_port_num(hsi, cl_info->info.port);
  96                        if (!p)
  97                                continue;
  98                        hsi_new_client(p, &cl_info->info);
  99                }
 100}
 101
 102static int hsi_remove_client(struct device *dev, void *data __maybe_unused)
 103{
 104        device_unregister(dev);
 105
 106        return 0;
 107}
 108
 109static int hsi_remove_port(struct device *dev, void *data __maybe_unused)
 110{
 111        device_for_each_child(dev, NULL, hsi_remove_client);
 112        device_unregister(dev);
 113
 114        return 0;
 115}
 116
 117static void hsi_controller_release(struct device *dev)
 118{
 119        struct hsi_controller *hsi = to_hsi_controller(dev);
 120
 121        kfree(hsi->port);
 122        kfree(hsi);
 123}
 124
 125static void hsi_port_release(struct device *dev)
 126{
 127        kfree(to_hsi_port(dev));
 128}
 129
 130/**
 131 * hsi_unregister_controller - Unregister an HSI controller
 132 * @hsi: The HSI controller to register
 133 */
 134void hsi_unregister_controller(struct hsi_controller *hsi)
 135{
 136        device_for_each_child(&hsi->device, NULL, hsi_remove_port);
 137        device_unregister(&hsi->device);
 138}
 139EXPORT_SYMBOL_GPL(hsi_unregister_controller);
 140
 141/**
 142 * hsi_register_controller - Register an HSI controller and its ports
 143 * @hsi: The HSI controller to register
 144 *
 145 * Returns -errno on failure, 0 on success.
 146 */
 147int hsi_register_controller(struct hsi_controller *hsi)
 148{
 149        unsigned int i;
 150        int err;
 151
 152        err = device_add(&hsi->device);
 153        if (err < 0)
 154                return err;
 155        for (i = 0; i < hsi->num_ports; i++) {
 156                hsi->port[i]->device.parent = &hsi->device;
 157                err = device_add(&hsi->port[i]->device);
 158                if (err < 0)
 159                        goto out;
 160        }
 161        /* Populate HSI bus with HSI clients */
 162        hsi_scan_board_info(hsi);
 163
 164        return 0;
 165out:
 166        while (i-- > 0)
 167                device_del(&hsi->port[i]->device);
 168        device_del(&hsi->device);
 169
 170        return err;
 171}
 172EXPORT_SYMBOL_GPL(hsi_register_controller);
 173
 174/**
 175 * hsi_register_client_driver - Register an HSI client to the HSI bus
 176 * @drv: HSI client driver to register
 177 *
 178 * Returns -errno on failure, 0 on success.
 179 */
 180int hsi_register_client_driver(struct hsi_client_driver *drv)
 181{
 182        drv->driver.bus = &hsi_bus_type;
 183
 184        return driver_register(&drv->driver);
 185}
 186EXPORT_SYMBOL_GPL(hsi_register_client_driver);
 187
 188static inline int hsi_dummy_msg(struct hsi_msg *msg __maybe_unused)
 189{
 190        return 0;
 191}
 192
 193static inline int hsi_dummy_cl(struct hsi_client *cl __maybe_unused)
 194{
 195        return 0;
 196}
 197
 198/**
 199 * hsi_put_controller - Free an HSI controller
 200 *
 201 * @hsi: Pointer to the HSI controller to freed
 202 *
 203 * HSI controller drivers should only use this function if they need
 204 * to free their allocated hsi_controller structures before a successful
 205 * call to hsi_register_controller. Other use is not allowed.
 206 */
 207void hsi_put_controller(struct hsi_controller *hsi)
 208{
 209        unsigned int i;
 210
 211        if (!hsi)
 212                return;
 213
 214        for (i = 0; i < hsi->num_ports; i++)
 215                if (hsi->port && hsi->port[i])
 216                        put_device(&hsi->port[i]->device);
 217        put_device(&hsi->device);
 218}
 219EXPORT_SYMBOL_GPL(hsi_put_controller);
 220
 221/**
 222 * hsi_alloc_controller - Allocate an HSI controller and its ports
 223 * @n_ports: Number of ports on the HSI controller
 224 * @flags: Kernel allocation flags
 225 *
 226 * Return NULL on failure or a pointer to an hsi_controller on success.
 227 */
 228struct hsi_controller *hsi_alloc_controller(unsigned int n_ports, gfp_t flags)
 229{
 230        struct hsi_controller   *hsi;
 231        struct hsi_port         **port;
 232        unsigned int            i;
 233
 234        if (!n_ports)
 235                return NULL;
 236
 237        hsi = kzalloc(sizeof(*hsi), flags);
 238        if (!hsi)
 239                return NULL;
 240        port = kzalloc(sizeof(*port)*n_ports, flags);
 241        if (!port) {
 242                kfree(hsi);
 243                return NULL;
 244        }
 245        hsi->num_ports = n_ports;
 246        hsi->port = port;
 247        hsi->device.release = hsi_controller_release;
 248        device_initialize(&hsi->device);
 249
 250        for (i = 0; i < n_ports; i++) {
 251                port[i] = kzalloc(sizeof(**port), flags);
 252                if (port[i] == NULL)
 253                        goto out;
 254                port[i]->num = i;
 255                port[i]->async = hsi_dummy_msg;
 256                port[i]->setup = hsi_dummy_cl;
 257                port[i]->flush = hsi_dummy_cl;
 258                port[i]->start_tx = hsi_dummy_cl;
 259                port[i]->stop_tx = hsi_dummy_cl;
 260                port[i]->release = hsi_dummy_cl;
 261                mutex_init(&port[i]->lock);
 262                ATOMIC_INIT_NOTIFIER_HEAD(&port[i]->n_head);
 263                dev_set_name(&port[i]->device, "port%d", i);
 264                hsi->port[i]->device.release = hsi_port_release;
 265                device_initialize(&hsi->port[i]->device);
 266        }
 267
 268        return hsi;
 269out:
 270        hsi_put_controller(hsi);
 271
 272        return NULL;
 273}
 274EXPORT_SYMBOL_GPL(hsi_alloc_controller);
 275
 276/**
 277 * hsi_free_msg - Free an HSI message
 278 * @msg: Pointer to the HSI message
 279 *
 280 * Client is responsible to free the buffers pointed by the scatterlists.
 281 */
 282void hsi_free_msg(struct hsi_msg *msg)
 283{
 284        if (!msg)
 285                return;
 286        sg_free_table(&msg->sgt);
 287        kfree(msg);
 288}
 289EXPORT_SYMBOL_GPL(hsi_free_msg);
 290
 291/**
 292 * hsi_alloc_msg - Allocate an HSI message
 293 * @nents: Number of memory entries
 294 * @flags: Kernel allocation flags
 295 *
 296 * nents can be 0. This mainly makes sense for read transfer.
 297 * In that case, HSI drivers will call the complete callback when
 298 * there is data to be read without consuming it.
 299 *
 300 * Return NULL on failure or a pointer to an hsi_msg on success.
 301 */
 302struct hsi_msg *hsi_alloc_msg(unsigned int nents, gfp_t flags)
 303{
 304        struct hsi_msg *msg;
 305        int err;
 306
 307        msg = kzalloc(sizeof(*msg), flags);
 308        if (!msg)
 309                return NULL;
 310
 311        if (!nents)
 312                return msg;
 313
 314        err = sg_alloc_table(&msg->sgt, nents, flags);
 315        if (unlikely(err)) {
 316                kfree(msg);
 317                msg = NULL;
 318        }
 319
 320        return msg;
 321}
 322EXPORT_SYMBOL_GPL(hsi_alloc_msg);
 323
 324/**
 325 * hsi_async - Submit an HSI transfer to the controller
 326 * @cl: HSI client sending the transfer
 327 * @msg: The HSI transfer passed to controller
 328 *
 329 * The HSI message must have the channel, ttype, complete and destructor
 330 * fields set beforehand. If nents > 0 then the client has to initialize
 331 * also the scatterlists to point to the buffers to write to or read from.
 332 *
 333 * HSI controllers relay on pre-allocated buffers from their clients and they
 334 * do not allocate buffers on their own.
 335 *
 336 * Once the HSI message transfer finishes, the HSI controller calls the
 337 * complete callback with the status and actual_len fields of the HSI message
 338 * updated. The complete callback can be called before returning from
 339 * hsi_async.
 340 *
 341 * Returns -errno on failure or 0 on success
 342 */
 343int hsi_async(struct hsi_client *cl, struct hsi_msg *msg)
 344{
 345        struct hsi_port *port = hsi_get_port(cl);
 346
 347        if (!hsi_port_claimed(cl))
 348                return -EACCES;
 349
 350        WARN_ON_ONCE(!msg->destructor || !msg->complete);
 351        msg->cl = cl;
 352
 353        return port->async(msg);
 354}
 355EXPORT_SYMBOL_GPL(hsi_async);
 356
 357/**
 358 * hsi_claim_port - Claim the HSI client's port
 359 * @cl: HSI client that wants to claim its port
 360 * @share: Flag to indicate if the client wants to share the port or not.
 361 *
 362 * Returns -errno on failure, 0 on success.
 363 */
 364int hsi_claim_port(struct hsi_client *cl, unsigned int share)
 365{
 366        struct hsi_port *port = hsi_get_port(cl);
 367        int err = 0;
 368
 369        mutex_lock(&port->lock);
 370        if ((port->claimed) && (!port->shared || !share)) {
 371                err = -EBUSY;
 372                goto out;
 373        }
 374        if (!try_module_get(to_hsi_controller(port->device.parent)->owner)) {
 375                err = -ENODEV;
 376                goto out;
 377        }
 378        port->claimed++;
 379        port->shared = !!share;
 380        cl->pclaimed = 1;
 381out:
 382        mutex_unlock(&port->lock);
 383
 384        return err;
 385}
 386EXPORT_SYMBOL_GPL(hsi_claim_port);
 387
 388/**
 389 * hsi_release_port - Release the HSI client's port
 390 * @cl: HSI client which previously claimed its port
 391 */
 392void hsi_release_port(struct hsi_client *cl)
 393{
 394        struct hsi_port *port = hsi_get_port(cl);
 395
 396        mutex_lock(&port->lock);
 397        /* Allow HW driver to do some cleanup */
 398        port->release(cl);
 399        if (cl->pclaimed)
 400                port->claimed--;
 401        BUG_ON(port->claimed < 0);
 402        cl->pclaimed = 0;
 403        if (!port->claimed)
 404                port->shared = 0;
 405        module_put(to_hsi_controller(port->device.parent)->owner);
 406        mutex_unlock(&port->lock);
 407}
 408EXPORT_SYMBOL_GPL(hsi_release_port);
 409
 410static int hsi_event_notifier_call(struct notifier_block *nb,
 411                                unsigned long event, void *data __maybe_unused)
 412{
 413        struct hsi_client *cl = container_of(nb, struct hsi_client, nb);
 414
 415        (*cl->ehandler)(cl, event);
 416
 417        return 0;
 418}
 419
 420/**
 421 * hsi_register_port_event - Register a client to receive port events
 422 * @cl: HSI client that wants to receive port events
 423 * @handler: Event handler callback
 424 *
 425 * Clients should register a callback to be able to receive
 426 * events from the ports. Registration should happen after
 427 * claiming the port.
 428 * The handler can be called in interrupt context.
 429 *
 430 * Returns -errno on error, or 0 on success.
 431 */
 432int hsi_register_port_event(struct hsi_client *cl,
 433                        void (*handler)(struct hsi_client *, unsigned long))
 434{
 435        struct hsi_port *port = hsi_get_port(cl);
 436
 437        if (!handler || cl->ehandler)
 438                return -EINVAL;
 439        if (!hsi_port_claimed(cl))
 440                return -EACCES;
 441        cl->ehandler = handler;
 442        cl->nb.notifier_call = hsi_event_notifier_call;
 443
 444        return atomic_notifier_chain_register(&port->n_head, &cl->nb);
 445}
 446EXPORT_SYMBOL_GPL(hsi_register_port_event);
 447
 448/**
 449 * hsi_unregister_port_event - Stop receiving port events for a client
 450 * @cl: HSI client that wants to stop receiving port events
 451 *
 452 * Clients should call this function before releasing their associated
 453 * port.
 454 *
 455 * Returns -errno on error, or 0 on success.
 456 */
 457int hsi_unregister_port_event(struct hsi_client *cl)
 458{
 459        struct hsi_port *port = hsi_get_port(cl);
 460        int err;
 461
 462        WARN_ON(!hsi_port_claimed(cl));
 463
 464        err = atomic_notifier_chain_unregister(&port->n_head, &cl->nb);
 465        if (!err)
 466                cl->ehandler = NULL;
 467
 468        return err;
 469}
 470EXPORT_SYMBOL_GPL(hsi_unregister_port_event);
 471
 472/**
 473 * hsi_event -Notifies clients about port events
 474 * @port: Port where the event occurred
 475 * @event: The event type
 476 *
 477 * Clients should not be concerned about wake line behavior. However, due
 478 * to a race condition in HSI HW protocol, clients need to be notified
 479 * about wake line changes, so they can implement a workaround for it.
 480 *
 481 * Events:
 482 * HSI_EVENT_START_RX - Incoming wake line high
 483 * HSI_EVENT_STOP_RX - Incoming wake line down
 484 *
 485 * Returns -errno on error, or 0 on success.
 486 */
 487int hsi_event(struct hsi_port *port, unsigned long event)
 488{
 489        return atomic_notifier_call_chain(&port->n_head, event, NULL);
 490}
 491EXPORT_SYMBOL_GPL(hsi_event);
 492
 493static int __init hsi_init(void)
 494{
 495        return bus_register(&hsi_bus_type);
 496}
 497postcore_initcall(hsi_init);
 498
 499static void __exit hsi_exit(void)
 500{
 501        bus_unregister(&hsi_bus_type);
 502}
 503module_exit(hsi_exit);
 504
 505MODULE_AUTHOR("Carlos Chinea <carlos.chinea@nokia.com>");
 506MODULE_DESCRIPTION("High-speed Synchronous Serial Interface (HSI) framework");
 507MODULE_LICENSE("GPL v2");
 508
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