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
  31 struct aim_channel {
  32         wait_queue_head_t wq;
  33         struct cdev cdev;
  34         struct device *dev;
  35         struct mutex io_mutex;
  36         struct most_interface *iface;
  37         struct most_channel_config *cfg;
  38         unsigned int channel_id;
  39         dev_t devno;
  40         bool keep_mbo;
  41         unsigned int mbo_offs;
  42         struct mbo *stacked_mbo;
  43         DECLARE_KFIFO_PTR(fifo, typeof(struct mbo *));
  44         atomic_t access_ref;
  45         struct list_head list;
  46 };
  47 #define to_channel(d) container_of(d, struct aim_channel, cdev)
  48 static struct list_head channel_list;
  49 static spinlock_t ch_list_lock;
  50
  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);
 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 == true)
 137                 most_put_mbo(channel->stacked_mbo);
 138         ret = most_stop_channel(channel->iface, channel->channel_id);
 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);
 169
 170         if (!mbo && channel->dev) {
 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                             (channel->dev == NULL)))
 178                         return -ERESTARTSYS;
 179         }
 180
 181         mutex_lock(&channel->io_mutex);
 182         if (unlikely(!channel->dev)) {
 183                 mutex_unlock(&channel->io_mutex);
 184                 err = -EPIPE;
 185                 goto error;
 186         }
 187         mutex_unlock(&channel->io_mutex);
 188
 189         max_len = channel->cfg->buffer_size;
 190         actual_len = min(count, max_len);
 191         mbo->buffer_length = actual_len;
 192
 193         retval = copy_from_user(mbo->virt_address, buf, mbo->buffer_length);
 194         if (retval) {
 195                 err = -EIO;
 196                 goto error;
 197         }
 198
 199         ret = most_submit_mbo(mbo);
 200         if (ret) {
 201                 pr_info("submitting MBO to core failed\n");
 202                 err = ret;
 203                 goto error;
 204         }
 205         return actual_len - retval;
 206 error:
 207         if (mbo)
 208                 most_put_mbo(mbo);
 209         return err;
 210 }
 211
 212 /**
 213  * aim_read - implements the syscall to read from the device
 214  * @filp: file pointer
 215  * @buf: pointer to user buffer
 216  * @count: number of bytes to read
 217  * @offset: offset from where to start reading
 218  */
 219 static ssize_t
 220 aim_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
 221 {
 222         ssize_t retval;
 223         size_t not_copied, proc_len;
 224         struct mbo *mbo;
 225         struct aim_channel *channel = filp->private_data;
 226
 227         if (channel->keep_mbo == true) {
 228                 mbo = channel->stacked_mbo;
 229                 channel->keep_mbo = false;
 230                 goto start_copy;
 231         }
 232         while ((0 == kfifo_out(&channel->fifo, &mbo, 1))
 233                && (channel->dev != NULL)) {
 234                 if (filp->f_flags & O_NONBLOCK)
 235                         return -EAGAIN;
 236                 if (wait_event_interruptible(channel->wq,
 237                                              (!kfifo_is_empty(&channel->fifo) ||
 238                                               (channel->dev == NULL))))
 239                         return -ERESTARTSYS;
 240         }
 241
 242 start_copy:
 243         /* make sure we don't submit to gone devices */
 244         mutex_lock(&channel->io_mutex);
 245         if (unlikely(!channel->dev)) {
 246                 mutex_unlock(&channel->io_mutex);
 247                 return -EIO;
 248         }
 249
 250         if (count < mbo->processed_length)
 251                 channel->keep_mbo = true;
 252
 253         proc_len = min((int)count,
 254                        (int)(mbo->processed_length - channel->mbo_offs));
 255
 256         not_copied = copy_to_user(buf,
 257                                   mbo->virt_address + channel->mbo_offs,
 258                                   proc_len);
 259
 260         retval = not_copied ? proc_len - not_copied : proc_len;
 261
 262         if (channel->keep_mbo == true) {
 263                 channel->mbo_offs = retval;
 264                 channel->stacked_mbo = mbo;
 265         } else {
 266                 most_put_mbo(mbo);
 267                 channel->mbo_offs = 0;
 268         }
 269         mutex_unlock(&channel->io_mutex);
 270         return retval;
 271 }
 272
 273 /**
 274  * Initialization of struct file_operations
 275  */
 276 static const struct file_operations channel_fops = {
 277         .owner = THIS_MODULE,
 278         .read = aim_read,
 279         .write = aim_write,
 280         .open = aim_open,
 281         .release = aim_close,
 282 };
 283
 284 /**
 285  * aim_disconnect_channel - disconnect a channel
 286  * @iface: pointer to interface instance
 287  * @channel_id: channel index
 288  *
 289  * This frees allocated memory and removes the cdev that represents this
 290  * channel in user space.
 291  */
 292 static int aim_disconnect_channel(struct most_interface *iface, int channel_id)
 293 {
 294         struct aim_channel *channel;
 295         unsigned long flags;
 296
 297         if (!iface) {
 298                 pr_info("Bad interface pointer\n");
 299                 return -EINVAL;
 300         }
 301
 302         channel = get_channel(iface, channel_id);
 303         if (channel == NULL)
 304                 return -ENXIO;
 305
 306         mutex_lock(&channel->io_mutex);
 307         channel->dev = NULL;
 308         mutex_unlock(&channel->io_mutex);
 309
 310         if (atomic_read(&channel->access_ref)) {
 311                 device_destroy(aim_class, channel->devno);
 312                 cdev_del(&channel->cdev);
 313                 kfifo_free(&channel->fifo);
 314                 ida_simple_remove(&minor_id, MINOR(channel->devno));
 315                 spin_lock_irqsave(&ch_list_lock, flags);
 316                 list_del(&channel->list);
 317                 spin_unlock_irqrestore(&ch_list_lock, flags);
 318                 kfree(channel);
 319         } else {
 320                 wake_up_interruptible(&channel->wq);
 321         }
 322         return 0;
 323 }
 324
 325 /**
 326  * aim_rx_completion - completion handler for rx channels
 327  * @mbo: pointer to buffer object that has completed
 328  *
 329  * This searches for the channel linked to this MBO and stores it in the local
 330  * fifo buffer.
 331  */
 332 static int aim_rx_completion(struct mbo *mbo)
 333 {
 334         struct aim_channel *channel;
 335
 336         if (!mbo)
 337                 return -EINVAL;
 338
 339         channel = get_channel(mbo->ifp, mbo->hdm_channel_id);
 340         if (channel == NULL)
 341                 return -ENXIO;
 342
 343         kfifo_in(&channel->fifo, &mbo, 1);
 344 #ifdef DEBUG_MESG
 345         if (kfifo_is_full(&channel->fifo))
 346                 pr_info("WARN: Fifo is full\n");
 347 #endif
 348         wake_up_interruptible(&channel->wq);
 349         return 0;
 350 }
 351
 352 /**
 353  * aim_tx_completion - completion handler for tx channels
 354  * @iface: pointer to interface instance
 355  * @channel_id: channel index/ID
 356  *
 357  * This wakes sleeping processes in the wait-queue.
 358  */
 359 static int aim_tx_completion(struct most_interface *iface, int channel_id)
 360 {
 361         struct aim_channel *channel;
 362
 363         if (!iface) {
 364                 pr_info("Bad interface pointer\n");
 365                 return -EINVAL;
 366         }
 367         if ((channel_id < 0) || (channel_id >= iface->num_channels)) {
 368                 pr_info("Channel ID out of range\n");
 369                 return -EINVAL;
 370         }
 371
 372         channel = get_channel(iface, channel_id);
 373         if (channel == NULL)
 374                 return -ENXIO;
 375         wake_up_interruptible(&channel->wq);
 376         return 0;
 377 }
 378
 379 static struct most_aim cdev_aim;
 380
 381 /**
 382  * aim_probe - probe function of the driver module
 383  * @iface: pointer to interface instance
 384  * @channel_id: channel index/ID
 385  * @cfg: pointer to actual channel configuration
 386  * @parent: pointer to kobject (needed for sysfs hook-up)
 387  * @name: name of the device to be created
 388  *
 389  * This allocates achannel object and creates the device node in /dev
 390  *
 391  * Returns 0 on success or error code otherwise.
 392  */
 393 static int aim_probe(struct most_interface *iface, int channel_id,
 394                      struct most_channel_config *cfg,
 395                      struct kobject *parent, char *name)
 396 {
 397         struct aim_channel *channel;
 398         unsigned long cl_flags;
 399         int retval;
 400         int current_minor;
 401
 402         if ((!iface) || (!cfg) || (!parent) || (!name)) {
 403                 pr_info("Probing AIM with bad arguments");
 404                 return -EINVAL;
 405         }
 406         channel = get_channel(iface, channel_id);
 407         if (channel)
 408                 return -EEXIST;
 409
 410         current_minor = ida_simple_get(&minor_id, 0, 0, GFP_KERNEL);
 411         if (current_minor < 0)
 412                 return current_minor;
 413
 414         channel = kzalloc(sizeof(*channel), GFP_KERNEL);
 415         if (!channel) {
 416                 pr_info("failed to alloc channel object\n");
 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");