drivers/staging/most/aim-cdev/cdev.c

   1 /*
   2  * cdev.c - Application interfacing module for character devices
   3  *
   4  * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG
   5  *
   6  * This program is distributed in the hope that it will be useful,
   7  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   8  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9  * GNU General Public License for more details.
  10  *
  11  * This file is licensed under GPLv2.
  12  */
  13
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15 #include <linux/module.h>
  16 #include <linux/sched.h>
  17 #include <linux/fs.h>
  18 #include <linux/slab.h>
  19 #include <linux/device.h>
  20 #include <linux/cdev.h>
  21 #include <linux/kfifo.h>
  22 #include <linux/uaccess.h>
  23 #include <linux/idr.h>
  24 #include "mostcore.h"
  25
  26 static dev_t aim_devno;
  27 static struct class *aim_class;
  28 static struct ida minor_id;
  29 static unsigned int major;
  30 static struct most_aim cdev_aim;
  31
  32 struct aim_channel {
  33         wait_queue_head_t wq;
  34         struct cdev cdev;
  35         struct device *dev;
  36         struct mutex io_mutex;
  37         struct most_interface *iface;
  38         struct most_channel_config *cfg;
  39         unsigned int channel_id;
  40         dev_t devno;
  41         bool keep_mbo;
  42         unsigned int mbo_offs;
  43         struct mbo *stacked_mbo;
  44         DECLARE_KFIFO_PTR(fifo, typeof(struct mbo *));
  45         atomic_t access_ref;
  46         struct list_head list;
  47 };
  48 #define to_channel(d) container_of(d, struct aim_channel, cdev)
  49 static struct list_head channel_list;
  50 static spinlock_t ch_list_lock;
  51
  52 static struct aim_channel *get_channel(struct most_interface *iface, int id)
  53 {
  54         struct aim_channel *channel, *tmp;
  55         unsigned long flags;
  56         int found_channel = 0;
  57
  58         spin_lock_irqsave(&ch_list_lock, flags);
  59         list_for_each_entry_safe(channel, tmp, &channel_list, list) {
  60                 if ((channel->iface == iface) && (channel->channel_id == id)) {
  61                         found_channel = 1;
  62                         break;
  63                 }
  64         }
  65         spin_unlock_irqrestore(&ch_list_lock, flags);
  66         if (!found_channel)
  67                 return NULL;
  68         return channel;
  69 }
  70
  71 /**
  72  * aim_open - implements the syscall to open the device
  73  * @inode: inode pointer
  74  * @filp: file pointer
  75  *
  76  * This stores the channel pointer in the private data field of
  77  * the file structure and activates the channel within the core.
  78  */
  79 static int aim_open(struct inode *inode, struct file *filp)
  80 {
  81         struct aim_channel *channel;
  82         int ret;
  83
  84         channel = to_channel(inode->i_cdev);
  85         filp->private_data = channel;
  86
  87         if (((channel->cfg->direction == MOST_CH_RX) &&
  88              ((filp->f_flags & O_ACCMODE) != O_RDONLY))
  89             || ((channel->cfg->direction == MOST_CH_TX) &&
  90                 ((filp->f_flags & O_ACCMODE) != O_WRONLY))) {
  91                 pr_info("WARN: Access flags mismatch\n");
  92                 return -EACCES;
  93         }
  94         if (!atomic_inc_and_test(&channel->access_ref)) {
  95                 pr_info("WARN: Device is busy\n");
  96                 atomic_dec(&channel->access_ref);
  97                 return -EBUSY;
  98         }
  99
 100         ret = most_start_channel(channel->iface, channel->channel_id, &cdev_aim);
 101         if (ret)
 102                 atomic_dec(&channel->access_ref);
 103         return ret;
 104 }
 105
 106 /**
 107  * aim_close - implements the syscall to close the device
 108  * @inode: inode pointer
 109  * @filp: file pointer
 110  *
 111  * This stops the channel within the core.
 112  */
 113 static int aim_close(struct inode *inode, struct file *filp)
 114 {
 115         int ret;
 116         struct mbo *mbo;
 117         struct aim_channel *channel = to_channel(inode->i_cdev);
 118
 119         mutex_lock(&channel->io_mutex);
 120         if (!channel->dev) {
 121                 mutex_unlock(&channel->io_mutex);
 122                 atomic_dec(&channel->access_ref);
 123                 device_destroy(aim_class, channel->devno);
 124                 cdev_del(&channel->cdev);
 125                 kfifo_free(&channel->fifo);
 126                 list_del(&channel->list);
 127                 ida_simple_remove(&minor_id, MINOR(channel->devno));
 128                 wake_up_interruptible(&channel->wq);
 129                 kfree(channel);
 130                 return 0;
 131         }
 132         mutex_unlock(&channel->io_mutex);
 133
 134         while (0 != kfifo_out((struct kfifo *)&channel->fifo, &mbo, 1))
 135                 most_put_mbo(mbo);
 136         if (channel->keep_mbo)
 137                 most_put_mbo(channel->stacked_mbo);
 138         ret = most_stop_channel(channel->iface, channel->channel_id, &cdev_aim);
 139         atomic_dec(&channel->access_ref);
 140         wake_up_interruptible(&channel->wq);
 141         return ret;
 142 }
 143
 144 /**
 145  * aim_write - implements the syscall to write to the device
 146  * @filp: file pointer
 147  * @buf: pointer to user buffer
 148  * @count: number of bytes to write
 149  * @offset: offset from where to start writing
 150  */
 151 static ssize_t aim_write(struct file *filp, const char __user *buf,
 152                          size_t count, loff_t *offset)
 153 {
 154         int ret, err;
 155         size_t actual_len = 0;
 156         size_t max_len = 0;
 157         ssize_t retval;
 158         struct mbo *mbo;
 159         struct aim_channel *channel = filp->private_data;
 160
 161         mutex_lock(&channel->io_mutex);
 162         if (unlikely(!channel->dev)) {
 163                 mutex_unlock(&channel->io_mutex);
 164                 return -EPIPE;
 165         }
 166         mutex_unlock(&channel->io_mutex);
 167
 168         mbo = most_get_mbo(channel->iface, channel->channel_id, &cdev_aim);
 169
 170         if (!mbo) {
 171                 if ((filp->f_flags & O_NONBLOCK))
 172                         return -EAGAIN;
 173                 if (wait_event_interruptible(
 174                             channel->wq,
 175                             (mbo = most_get_mbo(channel->iface,
 176                                                 channel->channel_id,
 177                                                 &cdev_aim)) ||
 178                             (!channel->dev)))
 179                         return -ERESTARTSYS;
 180         }
 181
 182         mutex_lock(&channel->io_mutex);
 183         if (unlikely(!channel->dev)) {
 184                 mutex_unlock(&channel->io_mutex);
 185                 err = -EPIPE;
 186                 goto error;
 187         }
 188         mutex_unlock(&channel->io_mutex);
 189
 190         max_len = channel->cfg->buffer_size;
 191         actual_len = min(count, max_len);
 192         mbo->buffer_length = actual_len;
 193
 194         retval = copy_from_user(mbo->virt_address, buf, mbo->buffer_length);
 195         if (retval) {
 196                 err = -EIO;
 197                 goto error;
 198         }
 199
 200         ret = most_submit_mbo(mbo);
 201         if (ret) {
 202                 pr_info("submitting MBO to core failed\n");
 203                 err = ret;
 204                 goto error;
 205         }
 206         return actual_len - retval;
 207 error:
 208         if (mbo)
 209                 most_put_mbo(mbo);
 210         return err;
 211 }
 212
 213 /**
 214  * aim_read - implements the syscall to read from the device
 215  * @filp: file pointer
 216  * @buf: pointer to user buffer
 217  * @count: number of bytes to read
 218  * @offset: offset from where to start reading
 219  */
 220 static ssize_t
 221 aim_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
 222 {
 223         ssize_t retval;
 224         size_t not_copied, proc_len;
 225         struct mbo *mbo;
 226         struct aim_channel *channel = filp->private_data;
 227
 228         if (channel->keep_mbo) {
 229                 mbo = channel->stacked_mbo;
 230                 channel->keep_mbo = false;
 231                 goto start_copy;
 232         }
 233         while ((0 == kfifo_out(&channel->fifo, &mbo, 1))
 234                && (channel->dev)) {
 235                 if (filp->f_flags & O_NONBLOCK)
 236                         return -EAGAIN;
 237                 if (wait_event_interruptible(channel->wq,
 238                                              (!kfifo_is_empty(&channel->fifo) ||
 239                                               (!channel->dev))))
 240                         return -ERESTARTSYS;
 241         }
 242
 243 start_copy:
 244         /* make sure we don't submit to gone devices */
 245         mutex_lock(&channel->io_mutex);
 246         if (unlikely(!channel->dev)) {
 247                 mutex_unlock(&channel->io_mutex);
 248                 return -EIO;
 249         }
 250
 251         if (count < mbo->processed_length)
 252                 channel->keep_mbo = true;
 253
 254         proc_len = min((int)count,
 255                        (int)(mbo->processed_length - channel->mbo_offs));
 256
 257         not_copied = copy_to_user(buf,
 258                                   mbo->virt_address + channel->mbo_offs,
 259                                   proc_len);
 260
 261         retval = not_copied ? proc_len - not_copied : proc_len;
 262
 263         if (channel->keep_mbo) {
 264                 channel->mbo_offs = retval;
 265                 channel->stacked_mbo = mbo;
 266         } else {
 267                 most_put_mbo(mbo);
 268                 channel->mbo_offs = 0;
 269         }
 270         mutex_unlock(&channel->io_mutex);
 271         return retval;
 272 }
 273
 274 /**
 275  * Initialization of struct file_operations
 276  */
 277 static const struct file_operations channel_fops = {
 278         .owner = THIS_MODULE,
 279         .read = aim_read,
 280         .write = aim_write,
 281         .open = aim_open,
 282         .release = aim_close,
 283 };
 284
 285 /**
 286  * aim_disconnect_channel - disconnect a channel
 287  * @iface: pointer to interface instance
 288  * @channel_id: channel index
 289  *
 290  * This frees allocated memory and removes the cdev that represents this
 291  * channel in user space.
 292  */
 293 static int aim_disconnect_channel(struct most_interface *iface, int channel_id)
 294 {
 295         struct aim_channel *channel;
 296         unsigned long flags;
 297
 298         if (!iface) {
 299                 pr_info("Bad interface pointer\n");
 300                 return -EINVAL;
 301         }
 302
 303         channel = get_channel(iface, channel_id);
 304         if (!channel)
 305                 return -ENXIO;
 306
 307         mutex_lock(&channel->io_mutex);
 308         channel->dev = NULL;
 309         mutex_unlock(&channel->io_mutex);
 310
 311         if (atomic_read(&channel->access_ref)) {
 312                 device_destroy(aim_class, channel->devno);
 313                 cdev_del(&channel->cdev);
 314                 kfifo_free(&channel->fifo);
 315                 ida_simple_remove(&minor_id, MINOR(channel->devno));
 316                 spin_lock_irqsave(&ch_list_lock, flags);
 317                 list_del(&channel->list);
 318                 spin_unlock_irqrestore(&ch_list_lock, flags);
 319                 kfree(channel);
 320         } else {
 321                 wake_up_interruptible(&channel->wq);
 322         }
 323         return 0;
 324 }
 325
 326 /**
 327  * aim_rx_completion - completion handler for rx channels
 328  * @mbo: pointer to buffer object that has completed
 329  *
 330  * This searches for the channel linked to this MBO and stores it in the local
 331  * fifo buffer.
 332  */
 333 static int aim_rx_completion(struct mbo *mbo)
 334 {
 335         struct aim_channel *channel;
 336
 337         if (!mbo)
 338                 return -EINVAL;
 339
 340         channel = get_channel(mbo->ifp, mbo->hdm_channel_id);
 341         if (!channel)
 342                 return -ENXIO;
 343
 344         kfifo_in(&channel->fifo, &mbo, 1);
 345 #ifdef DEBUG_MESG
 346         if (kfifo_is_full(&channel->fifo))
 347                 pr_info("WARN: Fifo is full\n");
 348 #endif
 349         wake_up_interruptible(&channel->wq);
 350         return 0;
 351 }
 352
 353 /**
 354  * aim_tx_completion - completion handler for tx channels
 355  * @iface: pointer to interface instance
 356  * @channel_id: channel index/ID
 357  *
 358  * This wakes sleeping processes in the wait-queue.
 359  */
 360 static int aim_tx_completion(struct most_interface *iface, int channel_id)
 361 {
 362         struct aim_channel *channel;
 363
 364         if (!iface) {
 365                 pr_info("Bad interface pointer\n");
 366                 return -EINVAL;
 367         }
 368         if ((channel_id < 0) || (channel_id >= iface->num_channels)) {
 369                 pr_info("Channel ID out of range\n");
 370                 return -EINVAL;
 371         }
 372
 373         channel = get_channel(iface, channel_id);
 374         if (!channel)
 375                 return -ENXIO;
 376         wake_up_interruptible(&channel->wq);
 377         return 0;
 378 }
 379
 380 static struct most_aim cdev_aim;
 381
 382 /**
 383  * aim_probe - probe function of the driver module
 384  * @iface: pointer to interface instance
 385  * @channel_id: channel index/ID
 386  * @cfg: pointer to actual channel configuration
 387  * @parent: pointer to kobject (needed for sysfs hook-up)
 388  * @name: name of the device to be created
 389  *
 390  * This allocates achannel object and creates the device node in /dev
 391  *
 392  * Returns 0 on success or error code otherwise.
 393  */
 394 static int aim_probe(struct most_interface *iface, int channel_id,
 395                      struct most_channel_config *cfg,
 396                      struct kobject *parent, char *name)
 397 {
 398         struct aim_channel *channel;
 399         unsigned long cl_flags;
 400         int retval;
 401         int current_minor;
 402
 403         if ((!iface) || (!cfg) || (!parent) || (!name)) {
 404                 pr_info("Probing AIM with bad arguments");
 405                 return -EINVAL;
 406         }
 407         channel = get_channel(iface, channel_id);
 408         if (channel)
 409                 return -EEXIST;
 410
 411         current_minor = ida_simple_get(&minor_id, 0, 0, GFP_KERNEL);
 412         if (current_minor < 0)
 413                 return current_minor;
 414
 415         channel = kzalloc(sizeof(*channel), GFP_KERNEL);
 416         if (!channel) {
 417                 retval = -ENOMEM;
 418                 goto error_alloc_channel;
 419         }
 420
 421         channel->devno = MKDEV(major, current_minor);
 422         cdev_init(&channel->cdev, &channel_fops);
 423         channel->cdev.owner = THIS_MODULE;
 424         cdev_add(&channel->cdev, channel->devno, 1);
 425         channel->iface = iface;
 426         channel->cfg = cfg;
 427         channel->channel_id = channel_id;
 428         channel->mbo_offs = 0;
 429         atomic_set(&channel->access_ref, -1);
 430         INIT_KFIFO(channel->fifo);
 431         retval = kfifo_alloc(&channel->fifo, cfg->num_buffers, GFP_KERNEL);
 432         if (retval) {
 433                 pr_info("failed to alloc channel kfifo");
 434                 goto error_alloc_kfifo;
 435         }
 436         init_waitqueue_head(&channel->wq);
 437         mutex_init(&channel->io_mutex);
 438         spin_lock_irqsave(&ch_list_lock, cl_flags);
 439         list_add_tail(&channel->list, &channel_list);
 440         spin_unlock_irqrestore(&ch_list_lock, cl_flags);
 441         channel->dev = device_create(aim_class,
 442                                      NULL,
 443                                      channel->devno,
 444                                      NULL,
 445                                      "%s", name);
 446
 447         retval = IS_ERR(channel->dev);
 448         if (retval) {
 449                 pr_info("failed to create new device node %s\n", name);
 450                 goto error_create_device;
 451         }
 452         kobject_uevent(&channel->dev->kobj, KOBJ_ADD);
 453         return 0;
 454
 455 error_create_device:
 456         kfifo_free(&channel->fifo);
 457         list_del(&channel->list);
 458 error_alloc_kfifo:
 459         cdev_del(&channel->cdev);
 460         kfree(channel);
 461 error_alloc_channel:
 462         ida_simple_remove(&minor_id, current_minor);
 463         return retval;
 464 }
 465
 466 static struct most_aim cdev_aim = {
 467         .name = "cdev",
 468         .probe_channel = aim_probe,
 469         .disconnect_channel = aim_disconnect_channel,
 470         .rx_completion = aim_rx_completion,
 471         .tx_completion = aim_tx_completion,
 472 };
 473
 474 static int __init mod_init(void)
 475 {
 476         pr_info("init()\n");
 477
 478         INIT_LIST_HEAD(&channel_list);
 479         spin_lock_init(&ch_list_lock);
 480         ida_init(&minor_id);
 481
 482         if (alloc_chrdev_region(&aim_devno, 0, 50, "cdev") < 0)
 483                 return -EIO;
 484         major = MAJOR(aim_devno);
 485
 486         aim_class = class_create(THIS_MODULE, "most_cdev_aim");
 487         if (IS_ERR(aim_class)) {
 488                 pr_err("no udev support\n");
 489                 goto free_cdev;
 490         }
 491
 492         if (most_register_aim(&cdev_aim))
 493                 goto dest_class;
 494         return 0;
 495
 496 dest_class:
 497         class_destroy(aim_class);
 498 free_cdev:
 499         unregister_chrdev_region(aim_devno, 1);
 500         return -EIO;
 501 }
 502
 503 static void __exit mod_exit(void)
 504 {
 505         struct aim_channel *channel, *tmp;
 506
 507         pr_info("exit module\n");
 508
 509         most_deregister_aim(&cdev_aim);
 510
 511         list_for_each_entry_safe(channel, tmp, &channel_list, list) {
 512                 device_destroy(aim_class, channel->devno);
 513                 cdev_del(&channel->cdev);
 514                 kfifo_free(&channel->fifo);
 515                 list_del(&channel->list);
 516                 ida_simple_remove(&minor_id, MINOR(channel->devno));
 517                 kfree(channel);
 518         }
 519         class_destroy(aim_class);
 520         unregister_chrdev_region(aim_devno, 1);
 521         ida_destroy(&minor_id);
 522 }
 523
 524 module_init(mod_init);
 525 module_exit(mod_exit);
 526 MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
 527 MODULE_LICENSE("GPL");
 528 MODULE_DESCRIPTION("character device AIM for mostcore");