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/poll.h>
  22 #include <linux/kfifo.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/idr.h>
  25 #include "mostcore.h"
  26
  27 static dev_t aim_devno;
  28 static struct class *aim_class;
  29 static struct ida minor_id;
  30 static unsigned int major;
  31 static struct most_aim cdev_aim;
  32
  33 struct aim_channel {
  34         wait_queue_head_t wq;
  35         struct cdev cdev;
  36         struct device *dev;
  37         struct mutex io_mutex;
  38         struct most_interface *iface;
  39         struct most_channel_config *cfg;
  40         unsigned int channel_id;
  41         dev_t devno;
  42         size_t 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
  49 #define to_channel(d) container_of(d, struct aim_channel, cdev)
  50 static struct list_head channel_list;
  51 static spinlock_t ch_list_lock;
  52
  53 static struct aim_channel *get_channel(struct most_interface *iface, int id)
  54 {
  55         struct aim_channel *channel, *tmp;
  56         unsigned long flags;
  57         int found_channel = 0;
  58
  59         spin_lock_irqsave(&ch_list_lock, flags);
  60         list_for_each_entry_safe(channel, tmp, &channel_list, list) {
  61                 if ((channel->iface == iface) && (channel->channel_id == id)) {
  62                         found_channel = 1;
  63                         break;
  64                 }
  65         }
  66         spin_unlock_irqrestore(&ch_list_lock, flags);
  67         if (!found_channel)
  68                 return NULL;
  69         return channel;
  70 }
  71
  72 /**
  73  * aim_open - implements the syscall to open the device
  74  * @inode: inode pointer
  75  * @filp: file pointer
  76  *
  77  * This stores the channel pointer in the private data field of
  78  * the file structure and activates the channel within the core.
  79  */
  80 static int aim_open(struct inode *inode, struct file *filp)
  81 {
  82         struct aim_channel *channel;
  83         int ret;
  84
  85         channel = to_channel(inode->i_cdev);
  86         filp->private_data = channel;
  87
  88         if (((channel->cfg->direction == MOST_CH_RX) &&
  89              ((filp->f_flags & O_ACCMODE) != O_RDONLY)) ||
  90              ((channel->cfg->direction == MOST_CH_TX) &&
  91                 ((filp->f_flags & O_ACCMODE) != O_WRONLY))) {
  92                 pr_info("WARN: Access flags mismatch\n");
  93                 return -EACCES;
  94         }
  95         if (!atomic_inc_and_test(&channel->access_ref)) {
  96                 pr_info("WARN: Device is busy\n");
  97                 atomic_dec(&channel->access_ref);
  98                 return -EBUSY;
  99         }
 100
 101         ret = most_start_channel(channel->iface, channel->channel_id,
 102                                  &cdev_aim);
 103         if (ret)
 104                 atomic_dec(&channel->access_ref);
 105         return ret;
 106 }
 107
 108 /**
 109  * aim_close - implements the syscall to close the device
 110  * @inode: inode pointer
 111  * @filp: file pointer
 112  *
 113  * This stops the channel within the core.
 114  */
 115 static int aim_close(struct inode *inode, struct file *filp)
 116 {
 117         int ret;
 118         struct mbo *mbo;
 119         struct aim_channel *channel = to_channel(inode->i_cdev);
 120
 121         mutex_lock(&channel->io_mutex);
 122         if (!channel->dev) {
 123                 mutex_unlock(&channel->io_mutex);
 124                 atomic_dec(&channel->access_ref);
 125                 device_destroy(aim_class, channel->devno);
 126                 cdev_del(&channel->cdev);
 127                 kfifo_free(&channel->fifo);
 128                 list_del(&channel->list);
 129                 ida_simple_remove(&minor_id, MINOR(channel->devno));
 130                 wake_up_interruptible(&channel->wq);
 131                 kfree(channel);
 132                 return 0;
 133         }
 134         mutex_unlock(&channel->io_mutex);
 135
 136         while (kfifo_out((struct kfifo *)&channel->fifo, &mbo, 1))
 137                 most_put_mbo(mbo);
 138         if (channel->stacked_mbo)
 139                 most_put_mbo(channel->stacked_mbo);
 140         ret = most_stop_channel(channel->iface, channel->channel_id, &cdev_aim);
 141         atomic_dec(&channel->access_ref);
 142         wake_up_interruptible(&channel->wq);
 143         return ret;
 144 }
 145
 146 /**
 147  * aim_write - implements the syscall to write to the device
 148  * @filp: file pointer
 149  * @buf: pointer to user buffer
 150  * @count: number of bytes to write
 151  * @offset: offset from where to start writing
 152  */
 153 static ssize_t aim_write(struct file *filp, const char __user *buf,
 154                          size_t count, loff_t *offset)
 155 {
 156         int ret, err;
 157         size_t actual_len = 0;
 158         size_t max_len = 0;
 159         ssize_t retval;
 160         struct mbo *mbo;
 161         struct aim_channel *channel = filp->private_data;
 162
 163         mutex_lock(&channel->io_mutex);
 164         if (unlikely(!channel->dev)) {
 165                 mutex_unlock(&channel->io_mutex);
 166                 return -EPIPE;
 167         }
 168         mutex_unlock(&channel->io_mutex);
 169
 170         mbo = most_get_mbo(channel->iface, channel->channel_id, &cdev_aim);
 171
 172         if (!mbo) {
 173                 if ((filp->f_flags & O_NONBLOCK))
 174                         return -EAGAIN;
 175                 if (wait_event_interruptible(
 176                             channel->wq,
 177                             (mbo = most_get_mbo(channel->iface,
 178                                                 channel->channel_id,
 179                                                 &cdev_aim)) ||
 180                             (!channel->dev)))
 181                         return -ERESTARTSYS;
 182         }
 183
 184         mutex_lock(&channel->io_mutex);
 185         if (unlikely(!channel->dev)) {
 186                 mutex_unlock(&channel->io_mutex);
 187                 err = -EPIPE;
 188                 goto error;
 189         }
 190         mutex_unlock(&channel->io_mutex);
 191
 192         max_len = channel->cfg->buffer_size;
 193         actual_len = min(count, max_len);
 194         mbo->buffer_length = actual_len;
 195
 196         retval = copy_from_user(mbo->virt_address, buf, mbo->buffer_length);
 197         if (retval) {
 198                 err = -EIO;
 199                 goto error;
 200         }
 201
 202         ret = most_submit_mbo(mbo);
 203         if (ret) {
 204                 pr_info("submitting MBO to core failed\n");
 205                 err = ret;
 206                 goto error;
 207         }
 208         return actual_len - retval;
 209 error:
 210         most_put_mbo(mbo);
 211         return err;
 212 }
 213
 214 /**
 215  * aim_read - implements the syscall to read from the device
 216  * @filp: file pointer
 217  * @buf: pointer to user buffer
 218  * @count: number of bytes to read
 219  * @offset: offset from where to start reading
 220  */
 221 static ssize_t
 222 aim_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
 223 {
 224         size_t to_copy, not_copied, copied;
 225         struct mbo *mbo;
 226         struct aim_channel *channel = filp->private_data;
 227
 228         if (channel->stacked_mbo) {
 229                 mbo = channel->stacked_mbo;
 230                 goto start_copy;
 231         }
 232         while ((!kfifo_out(&channel->fifo, &mbo, 1)) && (channel->dev)) {
 233                 if (filp->f_flags & O_NONBLOCK)
 234                         return -EAGAIN;
 235                 if (wait_event_interruptible(channel->wq,
 236                                              (!kfifo_is_empty(&channel->fifo) ||
 237                                               (!channel->dev))))
 238                         return -ERESTARTSYS;
 239         }
 240
 241 start_copy:
 242         /* make sure we don't submit to gone devices */
 243         mutex_lock(&channel->io_mutex);
 244         if (unlikely(!channel->dev)) {
 245                 mutex_unlock(&channel->io_mutex);
 246                 return -EIO;
 247         }
 248
 249         to_copy = min_t(size_t,
 250                         count,
 251                         mbo->processed_length - channel->mbo_offs);
 252
 253         not_copied = copy_to_user(buf,
 254                                   mbo->virt_address + channel->mbo_offs,
 255                                   to_copy);
 256
 257         copied = to_copy - not_copied;
 258
 259         if (count < mbo->processed_length) {
 260                 channel->mbo_offs = copied;
 261                 channel->stacked_mbo = mbo;
 262         } else {
 263                 most_put_mbo(mbo);
 264                 channel->mbo_offs = 0;
 265                 channel->stacked_mbo = NULL;
 266         }
 267         mutex_unlock(&channel->io_mutex);
 268         return copied;
 269 }
 270
 271 static inline bool __must_check IS_ERR_OR_FALSE(int x)
 272 {
 273         return x <= 0;
 274 }
 275
 276 static unsigned int aim_poll(struct file *filp, poll_table *wait)
 277 {
 278         struct aim_channel *c = filp->private_data;
 279         unsigned int mask = 0;
 280
 281         poll_wait(filp, &c->wq, wait);
 282
 283         if (c->cfg->direction == MOST_CH_RX) {
 284                 if (!kfifo_is_empty(&c->fifo))
 285                         mask |= POLLIN | POLLRDNORM;
 286         } else {
 287                 if (!IS_ERR_OR_FALSE(channel_has_mbo(c->iface, c->channel_id)))
 288                         mask |= POLLOUT | POLLWRNORM;
 289         }
 290         return mask;
 291 }
 292
 293 /**
 294  * Initialization of struct file_operations
 295  */
 296 static const struct file_operations channel_fops = {
 297         .owner = THIS_MODULE,
 298         .read = aim_read,
 299         .write = aim_write,
 300         .open = aim_open,
 301         .release = aim_close,
 302         .poll = aim_poll,
 303 };
 304
 305 /**
 306  * aim_disconnect_channel - disconnect a channel
 307  * @iface: pointer to interface instance
 308  * @channel_id: channel index
 309  *
 310  * This frees allocated memory and removes the cdev that represents this
 311  * channel in user space.
 312  */
 313 static int aim_disconnect_channel(struct most_interface *iface, int channel_id)
 314 {
 315         struct aim_channel *channel;
 316         unsigned long flags;
 317
 318         if (!iface) {
 319                 pr_info("Bad interface pointer\n");
 320                 return -EINVAL;
 321         }
 322
 323         channel = get_channel(iface, channel_id);
 324         if (!channel)
 325                 return -ENXIO;
 326
 327         mutex_lock(&channel->io_mutex);
 328         channel->dev = NULL;
 329         mutex_unlock(&channel->io_mutex);
 330
 331         if (atomic_read(&channel->access_ref)) {
 332                 device_destroy(aim_class, channel->devno);
 333                 cdev_del(&channel->cdev);
 334                 kfifo_free(&channel->fifo);
 335                 ida_simple_remove(&minor_id, MINOR(channel->devno));
 336                 spin_lock_irqsave(&ch_list_lock, flags);
 337                 list_del(&channel->list);
 338                 spin_unlock_irqrestore(&ch_list_lock, flags);
 339                 kfree(channel);
 340         } else {
 341                 wake_up_interruptible(&channel->wq);
 342         }
 343         return 0;
 344 }
 345
 346 /**
 347  * aim_rx_completion - completion handler for rx channels
 348  * @mbo: pointer to buffer object that has completed
 349  *
 350  * This searches for the channel linked to this MBO and stores it in the local
 351  * fifo buffer.
 352  */
 353 static int aim_rx_completion(struct mbo *mbo)
 354 {
 355         struct aim_channel *channel;
 356
 357         if (!mbo)
 358                 return -EINVAL;
 359
 360         channel = get_channel(mbo->ifp, mbo->hdm_channel_id);
 361         if (!channel)
 362                 return -ENXIO;
 363
 364         kfifo_in(&channel->fifo, &mbo, 1);
 365 #ifdef DEBUG_MESG
 366         if (kfifo_is_full(&channel->fifo))
 367                 pr_info("WARN: Fifo is full\n");
 368 #endif
 369         wake_up_interruptible(&channel->wq);
 370         return 0;
 371 }
 372
 373 /**
 374  * aim_tx_completion - completion handler for tx channels
 375  * @iface: pointer to interface instance
 376  * @channel_id: channel index/ID
 377  *
 378  * This wakes sleeping processes in the wait-queue.
 379  */
 380 static int aim_tx_completion(struct most_interface *iface, int channel_id)
 381 {
 382         struct aim_channel *channel;
 383
 384         if (!iface) {
 385                 pr_info("Bad interface pointer\n");
 386                 return -EINVAL;
 387         }
 388         if ((channel_id < 0) || (channel_id >= iface->num_channels)) {
 389                 pr_info("Channel ID out of range\n");
 390                 return -EINVAL;
 391         }
 392
 393         channel = get_channel(iface, channel_id);
 394         if (!channel)
 395                 return -ENXIO;
 396         wake_up_interruptible(&channel->wq);
 397         return 0;
 398 }
 399
 400 static struct most_aim cdev_aim;
 401
 402 /**
 403  * aim_probe - probe function of the driver module
 404  * @iface: pointer to interface instance
 405  * @channel_id: channel index/ID
 406  * @cfg: pointer to actual channel configuration
 407  * @parent: pointer to kobject (needed for sysfs hook-up)
 408  * @name: name of the device to be created
 409  *
 410  * This allocates achannel object and creates the device node in /dev
 411  *
 412  * Returns 0 on success or error code otherwise.
 413  */
 414 static int aim_probe(struct most_interface *iface, int channel_id,
 415                      struct most_channel_config *cfg,
 416                      struct kobject *parent, char *name)
 417 {
 418         struct aim_channel *channel;
 419         unsigned long cl_flags;
 420         int retval;
 421         int current_minor;
 422
 423         if ((!iface) || (!cfg) || (!parent) || (!name)) {
 424                 pr_info("Probing AIM with bad arguments");
 425                 return -EINVAL;
 426         }
 427         channel = get_channel(iface, channel_id);
 428         if (channel)
 429                 return -EEXIST;
 430
 431         current_minor = ida_simple_get(&minor_id, 0, 0, GFP_KERNEL);
 432         if (current_minor < 0)
 433                 return current_minor;
 434
 435         channel = kzalloc(sizeof(*channel), GFP_KERNEL);
 436         if (!channel) {
 437                 retval = -ENOMEM;
 438                 goto error_alloc_channel;
 439         }
 440
 441         channel->devno = MKDEV(major, current_minor);
 442         cdev_init(&channel->cdev, &channel_fops);
 443         channel->cdev.owner = THIS_MODULE;
 444         cdev_add(&channel->cdev, channel->devno, 1);
 445         channel->iface = iface;
 446         channel->cfg = cfg;
 447         channel->channel_id = channel_id;
 448         channel->mbo_offs = 0;
 449         atomic_set(&channel->access_ref, -1);
 450         INIT_KFIFO(channel->fifo);
 451         retval = kfifo_alloc(&channel->fifo, cfg->num_buffers, GFP_KERNEL);
 452         if (retval) {
 453                 pr_info("failed to alloc channel kfifo");
 454                 goto error_alloc_kfifo;
 455         }
 456         init_waitqueue_head(&channel->wq);
 457         mutex_init(&channel->io_mutex);
 458         spin_lock_irqsave(&ch_list_lock, cl_flags);
 459         list_add_tail(&channel->list, &channel_list);
 460         spin_unlock_irqrestore(&ch_list_lock, cl_flags);
 461         channel->dev = device_create(aim_class,
 462                                      NULL,
 463                                      channel->devno,
 464                                      NULL,
 465                                      "%s", name);
 466
 467         retval = IS_ERR(channel->dev);
 468         if (retval) {
 469                 pr_info("failed to create new device node %s\n", name);
 470                 goto error_create_device;
 471         }
 472         kobject_uevent(&channel->dev->kobj, KOBJ_ADD);
 473         return 0;
 474
 475 error_create_device:
 476         kfifo_free(&channel->fifo);
 477         list_del(&channel->list);
 478 error_alloc_kfifo:
 479         cdev_del(&channel->cdev);
 480         kfree(channel);
 481 error_alloc_channel:
 482         ida_simple_remove(&minor_id, current_minor);
 483         return retval;
 484 }
 485
 486 static struct most_aim cdev_aim = {
 487         .name = "cdev",
 488         .probe_channel = aim_probe,
 489         .disconnect_channel = aim_disconnect_channel,
 490         .rx_completion = aim_rx_completion,
 491         .tx_completion = aim_tx_completion,
 492 };
 493
 494 static int __init mod_init(void)
 495 {
 496         pr_info("init()\n");
 497
 498         INIT_LIST_HEAD(&channel_list);
 499         spin_lock_init(&ch_list_lock);
 500         ida_init(&minor_id);
 501
 502         if (alloc_chrdev_region(&aim_devno, 0, 50, "cdev") < 0)
 503                 return -EIO;
 504         major = MAJOR(aim_devno);
 505
 506         aim_class = class_create(THIS_MODULE, "most_cdev_aim");
 507         if (IS_ERR(aim_class)) {
 508                 pr_err("no udev support\n");
 509                 goto free_cdev;
 510         }
 511
 512         if (most_register_aim(&cdev_aim))
 513                 goto dest_class;
 514         return 0;
 515
 516 dest_class:
 517         class_destroy(aim_class);
 518 free_cdev:
 519         unregister_chrdev_region(aim_devno, 1);
 520         return -EIO;
 521 }
 522
 523 static void __exit mod_exit(void)
 524 {
 525         struct aim_channel *channel, *tmp;
 526
 527         pr_info("exit module\n");
 528
 529         most_deregister_aim(&cdev_aim);
 530
 531         list_for_each_entry_safe(channel, tmp, &channel_list, list) {
 532                 device_destroy(aim_class, channel->devno);
 533                 cdev_del(&channel->cdev);
 534                 kfifo_free(&channel->fifo);
 535                 list_del(&channel->list);
 536                 ida_simple_remove(&minor_id, MINOR(channel->devno));
 537                 kfree(channel);
 538         }
 539         class_destroy(aim_class);
 540         unregister_chrdev_region(aim_devno, 1);
 541         ida_destroy(&minor_id);
 542 }
 543
 544 module_init(mod_init);
 545 module_exit(mod_exit);
 546 MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
 547 MODULE_LICENSE("GPL");
 548 MODULE_DESCRIPTION("character device AIM for mostcore");