1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * cdev.c - Character device component for Mostcore 4 * 5 * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG 6 */ 7 8 #include <linux/module.h> 9 #include <linux/sched.h> 10 #include <linux/fs.h> 11 #include <linux/slab.h> 12 #include <linux/device.h> 13 #include <linux/cdev.h> 14 #include <linux/poll.h> 15 #include <linux/kfifo.h> 16 #include <linux/uaccess.h> 17 #include <linux/idr.h> 18 #include <linux/most.h> 19 20 #define CHRDEV_REGION_SIZE 50 21 22 static struct cdev_component { 23 dev_t devno; 24 struct ida minor_id; 25 unsigned int major; 26 struct class *class; 27 struct most_component cc; 28 } comp; 29 30 struct comp_channel { 31 wait_queue_head_t wq; 32 spinlock_t unlink; /* synchronization lock to unlink channels */ 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 size_t mbo_offs; 41 DECLARE_KFIFO_PTR(fifo, typeof(struct mbo *)); 42 int access_ref; 43 struct list_head list; 44 }; 45 46 #define to_channel(d) container_of(d, struct comp_channel, cdev) 47 static LIST_HEAD(channel_list); 48 static DEFINE_SPINLOCK(ch_list_lock); 49 50 static inline bool ch_has_mbo(struct comp_channel *c) 51 { 52 return channel_has_mbo(c->iface, c->channel_id, &comp.cc) > 0; 53 } 54 55 static inline struct mbo *ch_get_mbo(struct comp_channel *c, struct mbo **mbo) 56 { 57 if (!kfifo_peek(&c->fifo, mbo)) { 58 *mbo = most_get_mbo(c->iface, c->channel_id, &comp.cc); 59 if (*mbo) 60 kfifo_in(&c->fifo, mbo, 1); 61 } 62 return *mbo; 63 } 64 65 static struct comp_channel *get_channel(struct most_interface *iface, int id) 66 { 67 struct comp_channel *c, *tmp; 68 unsigned long flags; 69 70 spin_lock_irqsave(&ch_list_lock, flags); 71 list_for_each_entry_safe(c, tmp, &channel_list, list) { 72 if ((c->iface == iface) && (c->channel_id == id)) { 73 spin_unlock_irqrestore(&ch_list_lock, flags); 74 return c; 75 } 76 } 77 spin_unlock_irqrestore(&ch_list_lock, flags); 78 return NULL; 79 } 80 81 static void stop_channel(struct comp_channel *c) 82 { 83 struct mbo *mbo; 84 85 while (kfifo_out((struct kfifo *)&c->fifo, &mbo, 1)) 86 most_put_mbo(mbo); 87 most_stop_channel(c->iface, c->channel_id, &comp.cc); 88 } 89 90 static void destroy_cdev(struct comp_channel *c) 91 { 92 unsigned long flags; 93 94 device_destroy(comp.class, c->devno); 95 cdev_del(&c->cdev); 96 spin_lock_irqsave(&ch_list_lock, flags); 97 list_del(&c->list); 98 spin_unlock_irqrestore(&ch_list_lock, flags); 99 } 100 101 static void destroy_channel(struct comp_channel *c) 102 { 103 ida_simple_remove(&comp.minor_id, MINOR(c->devno)); 104 kfifo_free(&c->fifo); 105 kfree(c); 106 } 107 108 /** 109 * comp_open - implements the syscall to open the device 110 * @inode: inode pointer 111 * @filp: file pointer 112 * 113 * This stores the channel pointer in the private data field of 114 * the file structure and activates the channel within the core. 115 */ 116 static int comp_open(struct inode *inode, struct file *filp) 117 { 118 struct comp_channel *c; 119 int ret; 120 121 c = to_channel(inode->i_cdev); 122 filp->private_data = c; 123 124 if (((c->cfg->direction == MOST_CH_RX) && 125 ((filp->f_flags & O_ACCMODE) != O_RDONLY)) || 126 ((c->cfg->direction == MOST_CH_TX) && 127 ((filp->f_flags & O_ACCMODE) != O_WRONLY))) { 128 return -EACCES; 129 } 130 131 mutex_lock(&c->io_mutex); 132 if (!c->dev) { 133 mutex_unlock(&c->io_mutex); 134 return -ENODEV; 135 } 136 137 if (c->access_ref) { 138 mutex_unlock(&c->io_mutex); 139 return -EBUSY; 140 } 141 142 c->mbo_offs = 0; 143 ret = most_start_channel(c->iface, c->channel_id, &comp.cc); 144 if (!ret) 145 c->access_ref = 1; 146 mutex_unlock(&c->io_mutex); 147 return ret; 148 } 149 150 /** 151 * comp_close - implements the syscall to close the device 152 * @inode: inode pointer 153 * @filp: file pointer 154 * 155 * This stops the channel within the core. 156 */ 157 static int comp_close(struct inode *inode, struct file *filp) 158 { 159 struct comp_channel *c = to_channel(inode->i_cdev); 160 161 mutex_lock(&c->io_mutex); 162 spin_lock(&c->unlink); 163 c->access_ref = 0; 164 spin_unlock(&c->unlink); 165 if (c->dev) { 166 stop_channel(c); 167 mutex_unlock(&c->io_mutex); 168 } else { 169 mutex_unlock(&c->io_mutex); 170 destroy_channel(c); 171 } 172 return 0; 173 } 174 175 /** 176 * comp_write - implements the syscall to write to the device 177 * @filp: file pointer 178 * @buf: pointer to user buffer 179 * @count: number of bytes to write 180 * @offset: offset from where to start writing 181 */ 182 static ssize_t comp_write(struct file *filp, const char __user *buf, 183 size_t count, loff_t *offset) 184 { 185 int ret; 186 size_t to_copy, left; 187 struct mbo *mbo = NULL; 188 struct comp_channel *c = filp->private_data; 189 190 mutex_lock(&c->io_mutex); 191 while (c->dev && !ch_get_mbo(c, &mbo)) { 192 mutex_unlock(&c->io_mutex); 193 194 if ((filp->f_flags & O_NONBLOCK)) 195 return -EAGAIN; 196 if (wait_event_interruptible(c->wq, ch_has_mbo(c) || !c->dev)) 197 return -ERESTARTSYS; 198 mutex_lock(&c->io_mutex); 199 } 200 201 if (unlikely(!c->dev)) { 202 ret = -ENODEV; 203 goto unlock; 204 } 205 206 to_copy = min(count, c->cfg->buffer_size - c->mbo_offs); 207 left = copy_from_user(mbo->virt_address + c->mbo_offs, buf, to_copy); 208 if (left == to_copy) { 209 ret = -EFAULT; 210 goto unlock; 211 } 212 213 c->mbo_offs += to_copy - left; 214 if (c->mbo_offs >= c->cfg->buffer_size || 215 c->cfg->data_type == MOST_CH_CONTROL || 216 c->cfg->data_type == MOST_CH_ASYNC) { 217 kfifo_skip(&c->fifo); 218 mbo->buffer_length = c->mbo_offs; 219 c->mbo_offs = 0; 220 most_submit_mbo(mbo); 221 } 222 223 ret = to_copy - left; 224 unlock: 225 mutex_unlock(&c->io_mutex); 226 return ret; 227 } 228 229 /** 230 * comp_read - implements the syscall to read from the device 231 * @filp: file pointer 232 * @buf: pointer to user buffer 233 * @count: number of bytes to read 234 * @offset: offset from where to start reading 235 */ 236 static ssize_t 237 comp_read(struct file *filp, char __user *buf, size_t count, loff_t *offset) 238 { 239 size_t to_copy, not_copied, copied; 240 struct mbo *mbo = NULL; 241 struct comp_channel *c = filp->private_data; 242 243 mutex_lock(&c->io_mutex); 244 while (c->dev && !kfifo_peek(&c->fifo, &mbo)) { 245 mutex_unlock(&c->io_mutex); 246 if (filp->f_flags & O_NONBLOCK) 247 return -EAGAIN; 248 if (wait_event_interruptible(c->wq, 249 (!kfifo_is_empty(&c->fifo) || 250 (!c->dev)))) 251 return -ERESTARTSYS; 252 mutex_lock(&c->io_mutex); 253 } 254 255 /* make sure we don't submit to gone devices */ 256 if (unlikely(!c->dev)) { 257 mutex_unlock(&c->io_mutex); 258 return -ENODEV; 259 } 260 261 to_copy = min_t(size_t, 262 count, 263 mbo->processed_length - c->mbo_offs); 264 265 not_copied = copy_to_user(buf, 266 mbo->virt_address + c->mbo_offs, 267 to_copy); 268 269 copied = to_copy - not_copied; 270 271 c->mbo_offs += copied; 272 if (c->mbo_offs >= mbo->processed_length) { 273 kfifo_skip(&c->fifo); 274 most_put_mbo(mbo); 275 c->mbo_offs = 0; 276 } 277 mutex_unlock(&c->io_mutex); 278 return copied; 279 } 280 281 static __poll_t comp_poll(struct file *filp, poll_table *wait) 282 { 283 struct comp_channel *c = filp->private_data; 284 __poll_t mask = 0; 285 286 poll_wait(filp, &c->wq, wait); 287 288 mutex_lock(&c->io_mutex); 289 if (c->cfg->direction == MOST_CH_RX) { 290 if (!c->dev || !kfifo_is_empty(&c->fifo)) 291 mask |= EPOLLIN | EPOLLRDNORM; 292 } else { 293 if (!c->dev || !kfifo_is_empty(&c->fifo) || ch_has_mbo(c)) 294 mask |= EPOLLOUT | EPOLLWRNORM; 295 } 296 mutex_unlock(&c->io_mutex); 297 return mask; 298 } 299 300 /* 301 * Initialization of struct file_operations 302 */ 303 static const struct file_operations channel_fops = { 304 .owner = THIS_MODULE, 305 .read = comp_read, 306 .write = comp_write, 307 .open = comp_open, 308 .release = comp_close, 309 .poll = comp_poll, 310 }; 311 312 /** 313 * comp_disconnect_channel - disconnect a channel 314 * @iface: pointer to interface instance 315 * @channel_id: channel index 316 * 317 * This frees allocated memory and removes the cdev that represents this 318 * channel in user space. 319 */ 320 static int comp_disconnect_channel(struct most_interface *iface, int channel_id) 321 { 322 struct comp_channel *c; 323 324 c = get_channel(iface, channel_id); 325 if (!c) 326 return -EINVAL; 327 328 mutex_lock(&c->io_mutex); 329 spin_lock(&c->unlink); 330 c->dev = NULL; 331 spin_unlock(&c->unlink); 332 destroy_cdev(c); 333 if (c->access_ref) { 334 stop_channel(c); 335 wake_up_interruptible(&c->wq); 336 mutex_unlock(&c->io_mutex); 337 } else { 338 mutex_unlock(&c->io_mutex); 339 destroy_channel(c); 340 } 341 return 0; 342 } 343 344 /** 345 * comp_rx_completion - completion handler for rx channels 346 * @mbo: pointer to buffer object that has completed 347 * 348 * This searches for the channel linked to this MBO and stores it in the local 349 * fifo buffer. 350 */ 351 static int comp_rx_completion(struct mbo *mbo) 352 { 353 struct comp_channel *c; 354 355 if (!mbo) 356 return -EINVAL; 357 358 c = get_channel(mbo->ifp, mbo->hdm_channel_id); 359 if (!c) 360 return -EINVAL; 361 362 spin_lock(&c->unlink); 363 if (!c->access_ref || !c->dev) { 364 spin_unlock(&c->unlink); 365 return -ENODEV; 366 } 367 kfifo_in(&c->fifo, &mbo, 1); 368 spin_unlock(&c->unlink); 369 #ifdef DEBUG_MESG 370 if (kfifo_is_full(&c->fifo)) 371 dev_warn(c->dev, "Fifo is full\n"); 372 #endif 373 wake_up_interruptible(&c->wq); 374 return 0; 375 } 376 377 /** 378 * comp_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 comp_tx_completion(struct most_interface *iface, int channel_id) 385 { 386 struct comp_channel *c; 387 388 c = get_channel(iface, channel_id); 389 if (!c) 390 return -EINVAL; 391 392 if ((channel_id < 0) || (channel_id >= iface->num_channels)) { 393 dev_warn(c->dev, "Channel ID out of range\n"); 394 return -EINVAL; 395 } 396 397 wake_up_interruptible(&c->wq); 398 return 0; 399 } 400 401 /** 402 * comp_probe - probe function of the driver module 403 * @iface: pointer to interface instance 404 * @channel_id: channel index/ID 405 * @cfg: pointer to actual channel configuration 406 * @name: name of the device to be created 407 * @args: pointer to array of component parameters (from configfs) 408 * 409 * This allocates a channel object and creates the device node in /dev 410 * 411 * Returns 0 on success or error code otherwise. 412 */ 413 static int comp_probe(struct most_interface *iface, int channel_id, 414 struct most_channel_config *cfg, char *name, char *args) 415 { 416 struct comp_channel *c; 417 unsigned long cl_flags; 418 int retval; 419 int current_minor; 420 421 if (!cfg || !name) 422 return -EINVAL; 423 424 c = get_channel(iface, channel_id); 425 if (c) 426 return -EEXIST; 427 428 current_minor = ida_simple_get(&comp.minor_id, 0, 0, GFP_KERNEL); 429 if (current_minor < 0) 430 return current_minor; 431 432 c = kzalloc(sizeof(*c), GFP_KERNEL); 433 if (!c) { 434 retval = -ENOMEM; 435 goto err_remove_ida; 436 } 437 438 c->devno = MKDEV(comp.major, current_minor); 439 cdev_init(&c->cdev, &channel_fops); 440 c->cdev.owner = THIS_MODULE; 441 retval = cdev_add(&c->cdev, c->devno, 1); 442 if (retval < 0) 443 goto err_free_c; 444 c->iface = iface; 445 c->cfg = cfg; 446 c->channel_id = channel_id; 447 c->access_ref = 0; 448 spin_lock_init(&c->unlink); 449 INIT_KFIFO(c->fifo); 450 retval = kfifo_alloc(&c->fifo, cfg->num_buffers, GFP_KERNEL); 451 if (retval) 452 goto err_del_cdev_and_free_channel; 453 init_waitqueue_head(&c->wq); 454 mutex_init(&c->io_mutex); 455 spin_lock_irqsave(&ch_list_lock, cl_flags); 456 list_add_tail(&c->list, &channel_list); 457 spin_unlock_irqrestore(&ch_list_lock, cl_flags); 458 c->dev = device_create(comp.class, NULL, c->devno, NULL, "%s", name); 459 460 if (IS_ERR(c->dev)) { 461 retval = PTR_ERR(c->dev); 462 goto err_free_kfifo_and_del_list; 463 } 464 kobject_uevent(&c->dev->kobj, KOBJ_ADD); 465 return 0; 466 467 err_free_kfifo_and_del_list: 468 kfifo_free(&c->fifo); 469 list_del(&c->list); 470 err_del_cdev_and_free_channel: 471 cdev_del(&c->cdev); 472 err_free_c: 473 kfree(c); 474 err_remove_ida: 475 ida_simple_remove(&comp.minor_id, current_minor); 476 return retval; 477 } 478 479 static struct cdev_component comp = { 480 .cc = { 481 .mod = THIS_MODULE, 482 .name = "cdev", 483 .probe_channel = comp_probe, 484 .disconnect_channel = comp_disconnect_channel, 485 .rx_completion = comp_rx_completion, 486 .tx_completion = comp_tx_completion, 487 }, 488 }; 489 490 static int __init most_cdev_init(void) 491 { 492 int err; 493 494 comp.class = class_create("most_cdev"); 495 if (IS_ERR(comp.class)) 496 return PTR_ERR(comp.class); 497 498 ida_init(&comp.minor_id); 499 500 err = alloc_chrdev_region(&comp.devno, 0, CHRDEV_REGION_SIZE, "cdev"); 501 if (err < 0) 502 goto dest_ida; 503 comp.major = MAJOR(comp.devno); 504 err = most_register_component(&comp.cc); 505 if (err) 506 goto free_cdev; 507 err = most_register_configfs_subsys(&comp.cc); 508 if (err) 509 goto deregister_comp; 510 return 0; 511 512 deregister_comp: 513 most_deregister_component(&comp.cc); 514 free_cdev: 515 unregister_chrdev_region(comp.devno, CHRDEV_REGION_SIZE); 516 dest_ida: 517 ida_destroy(&comp.minor_id); 518 class_destroy(comp.class); 519 return err; 520 } 521 522 static void __exit most_cdev_exit(void) 523 { 524 struct comp_channel *c, *tmp; 525 526 most_deregister_configfs_subsys(&comp.cc); 527 most_deregister_component(&comp.cc); 528 529 list_for_each_entry_safe(c, tmp, &channel_list, list) { 530 destroy_cdev(c); 531 destroy_channel(c); 532 } 533 unregister_chrdev_region(comp.devno, CHRDEV_REGION_SIZE); 534 ida_destroy(&comp.minor_id); 535 class_destroy(comp.class); 536 } 537 538 module_init(most_cdev_init); 539 module_exit(most_cdev_exit); 540 MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>"); 541 MODULE_LICENSE("GPL"); 542 MODULE_DESCRIPTION("character device component for mostcore"); 543