kernel/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         bool keep_mbo;
  43         unsigned int mbo_offs;
  44         struct mbo *stacked_mbo;
  45         DECLARE_KFIFO_PTR(fifo, typeof(struct mbo *));
  46         atomic_t access_ref;
  47         struct list_head list;
  48 };
  49
  50 #define to_channel(d) container_of(d, struct aim_channel, cdev)
  51 static struct list_head channel_list;
  52 static spinlock_t ch_list_lock;
  53
  54 static struct aim_channel *get_channel(struct most_interface *iface, int id)
  55 {
  56         struct aim_channel *channel, *tmp;
  57         unsigned long flags;
  58         int found_channel = 0;
  59
  60         spin_lock_irqsave(&ch_list_lock, flags);
  61         list_for_each_entry_safe(channel, tmp, &channel_list, list) {
  62                 if ((channel->iface == iface) && (channel->channel_id == id)) {
  63                         found_channel = 1;
  64                         break;
  65                 }
  66         }
  67         spin_unlock_irqrestore(&ch_list_lock, flags);
  68         if (!found_channel)
  69                 return NULL;
  70         return channel;
  71 }
  72
  73 /**
  74  * aim_open - implements the syscall to open the device
  75  * @inode: inode pointer
  76  * @filp: file pointer
  77  *
  78  * This stores the channel pointer in the private data field of
  79  * the file structure and activates the channel within the core.
  80  */
  81 static int aim_open(struct inode *inode, struct file *filp)
  82 {
  83         struct aim_channel *channel;
  84         int ret;
  85
  86         channel = to_channel(inode->i_cdev);
  87         filp->private_data = channel;
  88
  89         if (((channel->cfg->direction == MOST_CH_RX) &&
  90              ((filp->f_flags & O_ACCMODE) != O_RDONLY)) ||
  91              ((channel->cfg->direction == MOST_CH_TX) &&
  92                 ((filp->f_flags & O_ACCMODE) != O_WRONLY))) {
  93                 pr_info("WARN: Access flags mismatch\n");
  94                 return -EACCES;
  95         }
  96         if (!atomic_inc_and_test(&channel->access_ref)) {
  97                 pr_info("WARN: Device is busy\n");
  98                 atomic_dec(&channel->access_ref);
  99                 return -EBUSY;
 100         }
 101
 102         ret = most_start_channel(channel->iface, channel->channel_id,
 103                                  &cdev_aim);
 104         if (ret)
 105                 atomic_dec(&channel->access_ref);
 106         return ret;
 107 }
 108
 109 /**
 110  * aim_close - implements the syscall to close the device
 111  * @inode: inode pointer
 112  * @filp: file pointer
 113  *
 114  * This stops the channel within the core.
 115  */
 116 static int aim_close(struct inode *inode, struct file *filp)
 117 {
 118         int ret;
 119         struct mbo *mbo;
 120         struct aim_channel *channel = to_channel(inode->i_cdev);
 121
 122         mutex_lock(&channel->io_mutex);
 123         if (!channel->dev) {
 124                 mutex_unlock(&channel->io_mutex);
 125                 atomic_dec(&channel->access_ref);
 126                 device_destroy(aim_class, channel->devno);
 127                 cdev_del(&channel->cdev);
 128                 kfifo_free(&channel->fifo);
 129                 list_del(&channel->list);
 130                 ida_simple_remove(&minor_id, MINOR(channel->devno));
 131                 wake_up_interruptible(&channel->wq);
 132                 kfree(channel);
 133                 return 0;
 134         }
 135         mutex_unlock(&channel->io_mutex);
 136
 137         while (kfifo_out((struct kfifo *)&channel->fifo, &mbo, 1))
 138                 most_put_mbo(mbo);
 139         if (channel->keep_mbo)
 140                 most_put_mbo(channel->stacked_mbo);
 141         ret = most_stop_channel(channel->iface, channel->channel_id, &cdev_aim);
 142         atomic_dec(&channel->access_ref);
 143         wake_up_interruptible(&channel->wq);
 144         return ret;
 145 }
 146
 147 /**
 148  * aim_write - implements the syscall to write to the device
 149  * @filp: file pointer
 150  * @buf: pointer to user buffer
 151  * @count: number of bytes to write
 152  * @offset: offset from where to start writing
 153  */
 154 static ssize_t aim_write(struct file *filp, const char __user *buf,
 155                          size_t count, loff_t *offset)
 156 {
 157         int ret, err;
 158         size_t actual_len = 0;
 159         size_t max_len = 0;
 160         ssize_t retval;
 161         struct mbo *mbo;
 162         struct aim_channel *channel = filp->private_data;
 163
 164         mutex_lock(&channel->io_mutex);
 165         if (unlikely(!channel->dev)) {
 166                 mutex_unlock(&channel->io_mutex);
 167                 return -EPIPE;
 168         }
 169         mutex_unlock(&channel->io_mutex);
 170
 171         mbo = most_get_mbo(channel->iface, channel->channel_id, &cdev_aim);
 172
 173         if (!mbo) {
 174                 if ((filp->f_flags & O_NONBLOCK))
 175                         return -EAGAIN;
 176                 if (wait_event_interruptible(
 177                             channel->wq,
 178                             (mbo = most_get_mbo(channel->iface,
 179                                                 channel->channel_id,
 180                                                 &cdev_aim)) ||
 181                             (!channel->dev)))
 182                         return -ERESTARTSYS;
 183         }
 184
 185         mutex_lock(&channel->io_mutex);
 186         if (unlikely(!channel->dev)) {
 187                 mutex_unlock(&channel->io_mutex);
 188                 err = -EPIPE;
 189                 goto error;
 190         }
 191         mutex_unlock(&channel->io_mutex);
 192
 193         max_len = channel->cfg->buffer_size;
 194         actual_len = min(count, max_len);
 195         mbo->buffer_length = actual_len;
 196
 197         retval = copy_from_user(mbo->virt_address, buf, mbo->buffer_length);
 198         if (retval) {
 199                 err = -EIO;
 200                 goto error;
 201         }
 202
 203         ret = most_submit_mbo(mbo);
 204         if (ret) {
 205                 pr_info("submitting MBO to core failed\n");
 206                 err = ret;
 207                 goto error;
 208         }
 209         return actual_len - retval;
 210 error:
 211         most_put_mbo(mbo);
 212         return err;
 213 }
 214
 215 /**
 216  * aim_read - implements the syscall to read from the device
 217  * @filp: file pointer
 218  * @buf: pointer to user buffer
 219  * @count: number of bytes to read
 220  * @offset: offset from where to start reading
 221  */
 222 static ssize_t
 223 aim_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
 224 {
 225         ssize_t retval;
 226         size_t not_copied, proc_len;
 227         struct mbo *mbo;
 228         struct aim_channel *channel = filp->private_data;
 229
 230         if (channel->keep_mbo) {
 231                 mbo = channel->stacked_mbo;
 232                 channel->keep_mbo = false;
 233                 goto start_copy;
 234         }
 235         while ((!kfifo_out(&channel->fifo, &mbo, 1)) && (channel->dev)) {
 236                 if (filp->f_flags & O_NONBLOCK)
 237                         return -EAGAIN;
 238                 if (wait_event_interruptible(channel->wq,
 239                                              (!kfifo_is_empty(&channel->fifo) ||
 240                                               (!channel->dev))))
 241                         return -ERESTARTSYS;
 242         }
 243
 244 start_copy:
 245         /* make sure we don't submit to gone devices */
 246         mutex_lock(&channel->io_mutex);
 247         if (unlikely(!channel->dev)) {
 248                 mutex_unlock(&channel->io_mutex);
 249                 return -EIO;
 250         }
 251
 252         if (count < mbo->processed_length)
 253                 channel->keep_mbo = true;
 254
 255         proc_len = min((int)count,
 256                        (int)(mbo->processed_length - channel->mbo_offs));
 257
 258         not_copied = copy_to_user(buf,
 259                                   mbo->virt_address + channel->mbo_offs,
 260                                   proc_len);
 261
 262         retval = not_copied ? proc_len - not_copied : proc_len;
 263
 264         if (channel->keep_mbo) {
 265                 channel->mbo_offs = retval;
 266                 channel->stacked_mbo = mbo;
 267         } else {
 268                 most_put_mbo(mbo);
 269                 channel->mbo_offs = 0;
 270         }
 271         mutex_unlock(&channel->io_mutex);
 272         return retval;
 273 }
 274
 275 static inline bool __must_check IS_ERR_OR_FALSE(int x)
 276 {
 277         return x <= 0;
 278 }
 279
 280 static unsigned int aim_poll(struct file *filp, poll_table *wait)
 281 {
 282         struct aim_channel *c = filp->private_data;
 283         unsigned int mask = 0;
 284
 285         poll_wait(filp, &c->wq, wait);
 286
 287         if (c->cfg->direction == MOST_CH_RX) {
 288                 if (!kfifo_is_empty(&c->fifo))
 289                         mask |= POLLIN | POLLRDNORM;
 290         } else {
 291                 if (!IS_ERR_OR_FALSE(channel_has_mbo(c->iface, c->channel_id)))
 292                         mask |= POLLOUT | POLLWRNORM;
 293         }
 294         return mask;
 295 }
 296
 297 /**
 298  * Initialization of struct file_operations
 299  */
 300 static const struct file_operations channel_fops = {
 301         .owner = THIS_MODULE,
 302         .read = aim_read,
 303         .write = aim_write,
 304         .open = aim_open,
 305         .release = aim_close,
 306         .poll = aim_poll,
 307 };
 308
 309 /**
 310  * aim_disconnect_channel - disconnect a channel
 311  * @iface: pointer to interface instance
 312  * @channel_id: channel index
 313  *
 314  * This frees allocated memory and removes the cdev that represents this
 315  * channel in user space.
 316  */
 317 static int aim_disconnect_channel(struct most_interface *iface, int channel_id)
 318 {
 319         struct aim_channel *channel;
 320         unsigned long flags;
 321
 322         if (!iface) {
 323                 pr_info("Bad interface pointer\n");
 324                 return -EINVAL;
 325         }
 326
 327         channel = get_channel(iface, channel_id);
 328         if (!channel)
 329                 return -ENXIO;
 330
 331         mutex_lock(&channel->io_mutex);
 332         channel->dev = NULL;
 333         mutex_unlock(&channel->io_mutex);
 334
 335         if (atomic_read(&channel->access_ref)) {
 336                 device_destroy(aim_class, channel->devno);
 337                 cdev_del(&channel->cdev);
 338                 kfifo_free(&channel->fifo);
 339                 ida_simple_remove(&minor_id, MINOR(channel->devno));
 340                 spin_lock_irqsave(&ch_list_lock, flags);
 341                 list_del(&channel->list);
 342                 spin_unlock_irqrestore(&ch_list_lock, flags);
 343                 kfree(channel);
 344         } else {
 345                 wake_up_interruptible(&channel->wq);
 346         }
 347         return 0;
 348 }
 349
 350 /**
 351  * aim_rx_completion - completion handler for rx channels
 352  * @mbo: pointer to buffer object that has completed
 353  *
 354  * This searches for the channel linked to this MBO and stores it in the local
 355  * fifo buffer.
 356  */
 357 static int aim_rx_completion(struct mbo *mbo)
 358 {
 359         struct aim_channel *channel;
 360
 361         if (!mbo)
 362                 return -EINVAL;
 363
 364         channel = get_channel(mbo->ifp, mbo->hdm_channel_id);
 365         if (!channel)
 366                 return -ENXIO;
 367
 368         kfifo_in(&channel->fifo, &mbo, 1);
 369 #ifdef DEBUG_MESG
 370         if (kfifo_is_full(&channel->fifo))
 371                 pr_info("WARN: Fifo is full\n");
 372 #endif
 373         wake_up_interruptible(&channel->wq);
 374         return 0;
 375 }
 376
 377 /**
 378  * aim_tx_completion - completion handler for tx channels
 379  * @iface: pointer to interface instance
 380  * @channel_id: channel index/ID
 381  *
 382  * This wakes sleeping processes in the wait-queue.
 383  */
 384 static int aim_tx_completion(struct most_interface *iface, int channel_id)
 385 {
 386         struct aim_channel *channel;
 387
 388         if (!iface) {
 389                 pr_info("Bad interface pointer\n");
 390                 return -EINVAL;
 391         }
 392         if ((channel_id < 0) || (channel_id >= iface->num_channels)) {
 393                 pr_info("Channel ID out of range\n");
 394                 return -EINVAL;
 395         }
 396
 397         channel = get_channel(iface, channel_id);
 398         if (!channel)
 399                 return -ENXIO;
 400         wake_up_interruptible(&channel->wq);
 401         return 0;
 402 }
 403
 404 static struct most_aim cdev_aim;
 405
 406 /**
 407  * aim_probe - probe function of the driver module
 408  * @iface: pointer to interface instance
 409  * @channel_id: channel index/ID
 410  * @cfg: pointer to actual channel configuration
 411  * @parent: pointer to kobject (needed for sysfs hook-up)
 412  * @name: name of the device to be created
 413  *
 414  * This allocates achannel object and creates the device node in /dev
 415  *
 416  * Returns 0 on success or error code otherwise.
 417  */
 418 static int aim_probe(struct most_interface *iface, int channel_id,
 419                      struct most_channel_config *cfg,
 420                      struct kobject *parent, char *name)
 421 {
 422         struct aim_channel *channel;
 423         unsigned long cl_flags;
 424         int retval;
 425         int current_minor;
 426
 427         if ((!iface) || (!cfg) || (!parent) || (!name)) {
 428                 pr_info("Probing AIM with bad arguments");
 429                 return -EINVAL;
 430         }
 431         channel = get_channel(iface, channel_id);
 432         if (channel)
 433                 return -EEXIST;
 434
 435         current_minor = ida_simple_get(&minor_id, 0, 0, GFP_KERNEL);
 436         if (current_minor < 0)
 437                 return current_minor;
 438
 439         channel = kzalloc(sizeof(*channel), GFP_KERNEL);
 440         if (!channel) {
 441                 retval = -ENOMEM;
 442                 goto error_alloc_channel;
 443         }
 444
 445         channel->devno = MKDEV(major, current_minor);
 446         cdev_init(&channel->cdev, &channel_fops);
 447         channel->cdev.owner = THIS_MODULE;
 448         cdev_add(&channel->cdev, channel->devno, 1);
 449         channel->iface = iface;
 450         channel->cfg = cfg;
 451         channel->channel_id = channel_id;
 452         channel->mbo_offs = 0;
 453         atomic_set(&channel->access_ref, -1);
 454         INIT_KFIFO(channel->fifo);
 455         retval = kfifo_alloc(&channel->fifo, cfg->num_buffers, GFP_KERNEL);
 456         if (retval) {
 457                 pr_info("failed to alloc channel kfifo");
 458                 goto error_alloc_kfifo;
 459         }
 460         init_waitqueue_head(&channel->wq);
 461         mutex_init(&channel->io_mutex);
 462         spin_lock_irqsave(&ch_list_lock, cl_flags);
 463         list_add_tail(&channel->list, &channel_list);
 464         spin_unlock_irqrestore(&ch_list_lock, cl_flags);
 465         channel->dev = device_create(aim_class,
 466                                      NULL,
 467                                      channel->devno,
 468                                      NULL,
 469                                      "%s", name);
 470
 471         retval = IS_ERR(channel->dev);
 472         if (retval) {
 473                 pr_info("failed to create new device node %s\n", name);
 474                 goto error_create_device;
 475         }
 476         kobject_uevent(&channel->dev->kobj, KOBJ_ADD);
 477         return 0;
 478
 479 error_create_device:
 480         kfifo_free(&channel->fifo);
 481         list_del(&channel->list);
 482 error_alloc_kfifo:
 483         cdev_del(&channel->cdev);
 484         kfree(channel);
 485 error_alloc_channel:
 486         ida_simple_remove(&minor_id, current_minor);
 487         return retval;
 488 }
 489
 490 static struct most_aim cdev_aim = {
 491         .name = "cdev",
 492         .probe_channel = aim_probe,
 493         .disconnect_channel = aim_disconnect_channel,
 494         .rx_completion = aim_rx_completion,
 495         .tx_completion = aim_tx_completion,
 496 };
 497
 498 static int __init mod_init(void)
 499 {
 500         pr_info("init()\n");
 501
 502         INIT_LIST_HEAD(&channel_list);
 503         spin_lock_init(&ch_list_lock);
 504         ida_init(&minor_id);
 505
 506         if (alloc_chrdev_region(&aim_devno, 0, 50, "cdev") < 0)
 507                 return -EIO;
 508         major = MAJOR(aim_devno);
 509
 510         aim_class = class_create(THIS_MODULE, "most_cdev_aim");
 511         if (IS_ERR(aim_class)) {
 512                 pr_err("no udev support\n");
 513                 goto free_cdev;
 514         }
 515
 516         if (most_register_aim(&cdev_aim))
 517                 goto dest_class;
 518         return 0;
 519
 520 dest_class:
 521         class_destroy(aim_class);
 522 free_cdev:
 523         unregister_chrdev_region(aim_devno, 1);
 524         return -EIO;
 525 }
 526
 527 static void __exit mod_exit(void)
 528 {
 529         struct aim_channel *channel, *tmp;
 530
 531         pr_info("exit module\n");
 532
 533         most_deregister_aim(&cdev_aim);
 534
 535         list_for_each_entry_safe(channel, tmp, &channel_list, list) {
 536                 device_destroy(aim_class, channel->devno);
 537                 cdev_del(&channel->cdev);
 538                 kfifo_free(&channel->fifo);
 539                 list_del(&channel->list);
 540                 ida_simple_remove(&minor_id, MINOR(channel->devno));
 541                 kfree(channel);
 542         }
 543         class_destroy(aim_class);
 544         unregister_chrdev_region(aim_devno, 1);
 545         ida_destroy(&minor_id);
 546 }
 547
 548 module_init(mod_init);
 549 module_exit(mod_exit);
 550 MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
 551 MODULE_LICENSE("GPL");
 552 MODULE_DESCRIPTION("character device AIM for mostcore");