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 spinlock_t unlink; /* synchronization lock to unlink channels */
36 struct cdev cdev;
37 struct device *dev;
38 struct mutex io_mutex;
39 struct most_interface *iface;
40 struct most_channel_config *cfg;
41 unsigned int channel_id;
42 dev_t devno;
43 size_t mbo_offs;
44 DECLARE_KFIFO_PTR(fifo, typeof(struct mbo *));
45 int 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
ch_has_mbo(struct aim_channel * c)53 static inline bool ch_has_mbo(struct aim_channel *c)
54 {
55 return channel_has_mbo(c->iface, c->channel_id, &cdev_aim) > 0;
56 }
57
ch_get_mbo(struct aim_channel * c,struct mbo ** mbo)58 static inline bool ch_get_mbo(struct aim_channel *c, struct mbo **mbo)
59 {
60 if (!kfifo_peek(&c->fifo, mbo)) {
61 *mbo = most_get_mbo(c->iface, c->channel_id, &cdev_aim);
62 if (*mbo)
63 kfifo_in(&c->fifo, mbo, 1);
64 }
65 return *mbo;
66 }
67
get_channel(struct most_interface * iface,int id)68 static struct aim_channel *get_channel(struct most_interface *iface, int id)
69 {
70 struct aim_channel *c, *tmp;
71 unsigned long flags;
72 int found_channel = 0;
73
74 spin_lock_irqsave(&ch_list_lock, flags);
75 list_for_each_entry_safe(c, tmp, &channel_list, list) {
76 if ((c->iface == iface) && (c->channel_id == id)) {
77 found_channel = 1;
78 break;
79 }
80 }
81 spin_unlock_irqrestore(&ch_list_lock, flags);
82 if (!found_channel)
83 return NULL;
84 return c;
85 }
86
stop_channel(struct aim_channel * c)87 static void stop_channel(struct aim_channel *c)
88 {
89 struct mbo *mbo;
90
91 while (kfifo_out((struct kfifo *)&c->fifo, &mbo, 1))
92 most_put_mbo(mbo);
93 most_stop_channel(c->iface, c->channel_id, &cdev_aim);
94 }
95
destroy_cdev(struct aim_channel * c)96 static void destroy_cdev(struct aim_channel *c)
97 {
98 unsigned long flags;
99
100 device_destroy(aim_class, c->devno);
101 cdev_del(&c->cdev);
102 kfifo_free(&c->fifo);
103 spin_lock_irqsave(&ch_list_lock, flags);
104 list_del(&c->list);
105 spin_unlock_irqrestore(&ch_list_lock, flags);
106 ida_simple_remove(&minor_id, MINOR(c->devno));
107 }
108
109 /**
110 * aim_open - implements the syscall to open the device
111 * @inode: inode pointer
112 * @filp: file pointer
113 *
114 * This stores the channel pointer in the private data field of
115 * the file structure and activates the channel within the core.
116 */
aim_open(struct inode * inode,struct file * filp)117 static int aim_open(struct inode *inode, struct file *filp)
118 {
119 struct aim_channel *c;
120 int ret;
121
122 c = to_channel(inode->i_cdev);
123 filp->private_data = c;
124
125 if (((c->cfg->direction == MOST_CH_RX) &&
126 ((filp->f_flags & O_ACCMODE) != O_RDONLY)) ||
127 ((c->cfg->direction == MOST_CH_TX) &&
128 ((filp->f_flags & O_ACCMODE) != O_WRONLY))) {
129 pr_info("WARN: Access flags mismatch\n");
130 return -EACCES;
131 }
132
133 mutex_lock(&c->io_mutex);
134 if (!c->dev) {
135 pr_info("WARN: Device is destroyed\n");
136 mutex_unlock(&c->io_mutex);
137 return -ENODEV;
138 }
139
140 if (c->access_ref) {
141 pr_info("WARN: Device is busy\n");
142 mutex_unlock(&c->io_mutex);
143 return -EBUSY;
144 }
145
146 c->mbo_offs = 0;
147 ret = most_start_channel(c->iface, c->channel_id, &cdev_aim);
148 if (!ret)
149 c->access_ref = 1;
150 mutex_unlock(&c->io_mutex);
151 return ret;
152 }
153
154 /**
155 * aim_close - implements the syscall to close the device
156 * @inode: inode pointer
157 * @filp: file pointer
158 *
159 * This stops the channel within the core.
160 */
aim_close(struct inode * inode,struct file * filp)161 static int aim_close(struct inode *inode, struct file *filp)
162 {
163 struct aim_channel *c = to_channel(inode->i_cdev);
164
165 mutex_lock(&c->io_mutex);
166 spin_lock(&c->unlink);
167 c->access_ref = 0;
168 spin_unlock(&c->unlink);
169 if (c->dev) {
170 stop_channel(c);
171 mutex_unlock(&c->io_mutex);
172 } else {
173 destroy_cdev(c);
174 mutex_unlock(&c->io_mutex);
175 kfree(c);
176 }
177 return 0;
178 }
179
180 /**
181 * aim_write - implements the syscall to write to the device
182 * @filp: file pointer
183 * @buf: pointer to user buffer
184 * @count: number of bytes to write
185 * @offset: offset from where to start writing
186 */
aim_write(struct file * filp,const char __user * buf,size_t count,loff_t * offset)187 static ssize_t aim_write(struct file *filp, const char __user *buf,
188 size_t count, loff_t *offset)
189 {
190 int ret;
191 size_t to_copy, left;
192 struct mbo *mbo = NULL;
193 struct aim_channel *c = filp->private_data;
194
195 mutex_lock(&c->io_mutex);
196 while (c->dev && !ch_get_mbo(c, &mbo)) {
197 mutex_unlock(&c->io_mutex);
198
199 if ((filp->f_flags & O_NONBLOCK))
200 return -EAGAIN;
201 if (wait_event_interruptible(c->wq, ch_has_mbo(c) || !c->dev))
202 return -ERESTARTSYS;
203 mutex_lock(&c->io_mutex);
204 }
205
206 if (unlikely(!c->dev)) {
207 ret = -ENODEV;
208 goto unlock;
209 }
210
211 to_copy = min(count, c->cfg->buffer_size - c->mbo_offs);
212 left = copy_from_user(mbo->virt_address + c->mbo_offs, buf, to_copy);
213 if (left == to_copy) {
214 ret = -EFAULT;
215 goto unlock;
216 }
217
218 c->mbo_offs += to_copy - left;
219 if (c->mbo_offs >= c->cfg->buffer_size ||
220 c->cfg->data_type == MOST_CH_CONTROL ||
221 c->cfg->data_type == MOST_CH_ASYNC) {
222 kfifo_skip(&c->fifo);
223 mbo->buffer_length = c->mbo_offs;
224 c->mbo_offs = 0;
225 most_submit_mbo(mbo);
226 }
227
228 ret = to_copy - left;
229 unlock:
230 mutex_unlock(&c->io_mutex);
231 return ret;
232 }
233
234 /**
235 * aim_read - implements the syscall to read from the device
236 * @filp: file pointer
237 * @buf: pointer to user buffer
238 * @count: number of bytes to read
239 * @offset: offset from where to start reading
240 */
241 static ssize_t
aim_read(struct file * filp,char __user * buf,size_t count,loff_t * offset)242 aim_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
243 {
244 size_t to_copy, not_copied, copied;
245 struct mbo *mbo;
246 struct aim_channel *c = filp->private_data;
247
248 mutex_lock(&c->io_mutex);
249 while (c->dev && !kfifo_peek(&c->fifo, &mbo)) {
250 mutex_unlock(&c->io_mutex);
251 if (filp->f_flags & O_NONBLOCK)
252 return -EAGAIN;
253 if (wait_event_interruptible(c->wq,
254 (!kfifo_is_empty(&c->fifo) ||
255 (!c->dev))))
256 return -ERESTARTSYS;
257 mutex_lock(&c->io_mutex);
258 }
259
260 /* make sure we don't submit to gone devices */
261 if (unlikely(!c->dev)) {
262 mutex_unlock(&c->io_mutex);
263 return -ENODEV;
264 }
265
266 to_copy = min_t(size_t,
267 count,
268 mbo->processed_length - c->mbo_offs);
269
270 not_copied = copy_to_user(buf,
271 mbo->virt_address + c->mbo_offs,
272 to_copy);
273
274 copied = to_copy - not_copied;
275
276 c->mbo_offs += copied;
277 if (c->mbo_offs >= mbo->processed_length) {
278 kfifo_skip(&c->fifo);
279 most_put_mbo(mbo);
280 c->mbo_offs = 0;
281 }
282 mutex_unlock(&c->io_mutex);
283 return copied;
284 }
285
aim_poll(struct file * filp,poll_table * wait)286 static unsigned int aim_poll(struct file *filp, poll_table *wait)
287 {
288 struct aim_channel *c = filp->private_data;
289 unsigned int mask = 0;
290
291 poll_wait(filp, &c->wq, wait);
292
293 if (c->cfg->direction == MOST_CH_RX) {
294 if (!kfifo_is_empty(&c->fifo))
295 mask |= POLLIN | POLLRDNORM;
296 } else {
297 if (!kfifo_is_empty(&c->fifo) || ch_has_mbo(c))
298 mask |= POLLOUT | POLLWRNORM;
299 }
300 return mask;
301 }
302
303 /**
304 * Initialization of struct file_operations
305 */
306 static const struct file_operations channel_fops = {
307 .owner = THIS_MODULE,
308 .read = aim_read,
309 .write = aim_write,
310 .open = aim_open,
311 .release = aim_close,
312 .poll = aim_poll,
313 };
314
315 /**
316 * aim_disconnect_channel - disconnect a channel
317 * @iface: pointer to interface instance
318 * @channel_id: channel index
319 *
320 * This frees allocated memory and removes the cdev that represents this
321 * channel in user space.
322 */
aim_disconnect_channel(struct most_interface * iface,int channel_id)323 static int aim_disconnect_channel(struct most_interface *iface, int channel_id)
324 {
325 struct aim_channel *c;
326
327 if (!iface) {
328 pr_info("Bad interface pointer\n");
329 return -EINVAL;
330 }
331
332 c = get_channel(iface, channel_id);
333 if (!c)
334 return -ENXIO;
335
336 mutex_lock(&c->io_mutex);
337 spin_lock(&c->unlink);
338 c->dev = NULL;
339 spin_unlock(&c->unlink);
340 if (c->access_ref) {
341 stop_channel(c);
342 wake_up_interruptible(&c->wq);
343 mutex_unlock(&c->io_mutex);
344 } else {
345 destroy_cdev(c);
346 mutex_unlock(&c->io_mutex);
347 kfree(c);
348 }
349 return 0;
350 }
351
352 /**
353 * aim_rx_completion - completion handler for rx channels
354 * @mbo: pointer to buffer object that has completed
355 *
356 * This searches for the channel linked to this MBO and stores it in the local
357 * fifo buffer.
358 */
aim_rx_completion(struct mbo * mbo)359 static int aim_rx_completion(struct mbo *mbo)
360 {
361 struct aim_channel *c;
362
363 if (!mbo)
364 return -EINVAL;
365
366 c = get_channel(mbo->ifp, mbo->hdm_channel_id);
367 if (!c)
368 return -ENXIO;
369
370 spin_lock(&c->unlink);
371 if (!c->access_ref || !c->dev) {
372 spin_unlock(&c->unlink);
373 return -ENODEV;
374 }
375 kfifo_in(&c->fifo, &mbo, 1);
376 spin_unlock(&c->unlink);
377 #ifdef DEBUG_MESG
378 if (kfifo_is_full(&c->fifo))
379 pr_info("WARN: Fifo is full\n");
380 #endif
381 wake_up_interruptible(&c->wq);
382 return 0;
383 }
384
385 /**
386 * aim_tx_completion - completion handler for tx channels
387 * @iface: pointer to interface instance
388 * @channel_id: channel index/ID
389 *
390 * This wakes sleeping processes in the wait-queue.
391 */
aim_tx_completion(struct most_interface * iface,int channel_id)392 static int aim_tx_completion(struct most_interface *iface, int channel_id)
393 {
394 struct aim_channel *c;
395
396 if (!iface) {
397 pr_info("Bad interface pointer\n");
398 return -EINVAL;
399 }
400 if ((channel_id < 0) || (channel_id >= iface->num_channels)) {
401 pr_info("Channel ID out of range\n");
402 return -EINVAL;
403 }
404
405 c = get_channel(iface, channel_id);
406 if (!c)
407 return -ENXIO;
408 wake_up_interruptible(&c->wq);
409 return 0;
410 }
411
412 /**
413 * aim_probe - probe function of the driver module
414 * @iface: pointer to interface instance
415 * @channel_id: channel index/ID
416 * @cfg: pointer to actual channel configuration
417 * @parent: pointer to kobject (needed for sysfs hook-up)
418 * @name: name of the device to be created
419 *
420 * This allocates achannel object and creates the device node in /dev
421 *
422 * Returns 0 on success or error code otherwise.
423 */
aim_probe(struct most_interface * iface,int channel_id,struct most_channel_config * cfg,struct kobject * parent,char * name)424 static int aim_probe(struct most_interface *iface, int channel_id,
425 struct most_channel_config *cfg,
426 struct kobject *parent, char *name)
427 {
428 struct aim_channel *c;
429 unsigned long cl_flags;
430 int retval;
431 int current_minor;
432
433 if ((!iface) || (!cfg) || (!parent) || (!name)) {
434 pr_info("Probing AIM with bad arguments");
435 return -EINVAL;
436 }
437 c = get_channel(iface, channel_id);
438 if (c)
439 return -EEXIST;
440
441 current_minor = ida_simple_get(&minor_id, 0, 0, GFP_KERNEL);
442 if (current_minor < 0)
443 return current_minor;
444
445 c = kzalloc(sizeof(*c), GFP_KERNEL);
446 if (!c) {
447 retval = -ENOMEM;
448 goto error_alloc_channel;
449 }
450
451 c->devno = MKDEV(major, current_minor);
452 cdev_init(&c->cdev, &channel_fops);
453 c->cdev.owner = THIS_MODULE;
454 cdev_add(&c->cdev, c->devno, 1);
455 c->iface = iface;
456 c->cfg = cfg;
457 c->channel_id = channel_id;
458 c->access_ref = 0;
459 spin_lock_init(&c->unlink);
460 INIT_KFIFO(c->fifo);
461 retval = kfifo_alloc(&c->fifo, cfg->num_buffers, GFP_KERNEL);
462 if (retval) {
463 pr_info("failed to alloc channel kfifo");
464 goto error_alloc_kfifo;
465 }
466 init_waitqueue_head(&c->wq);
467 mutex_init(&c->io_mutex);
468 spin_lock_irqsave(&ch_list_lock, cl_flags);
469 list_add_tail(&c->list, &channel_list);
470 spin_unlock_irqrestore(&ch_list_lock, cl_flags);
471 c->dev = device_create(aim_class,
472 NULL,
473 c->devno,
474 NULL,
475 "%s", name);
476
477 if (IS_ERR(c->dev)) {
478 retval = PTR_ERR(c->dev);
479 pr_info("failed to create new device node %s\n", name);
480 goto error_create_device;
481 }
482 kobject_uevent(&c->dev->kobj, KOBJ_ADD);
483 return 0;
484
485 error_create_device:
486 kfifo_free(&c->fifo);
487 list_del(&c->list);
488 error_alloc_kfifo:
489 cdev_del(&c->cdev);
490 kfree(c);
491 error_alloc_channel:
492 ida_simple_remove(&minor_id, current_minor);
493 return retval;
494 }
495
496 static struct most_aim cdev_aim = {
497 .name = "cdev",
498 .probe_channel = aim_probe,
499 .disconnect_channel = aim_disconnect_channel,
500 .rx_completion = aim_rx_completion,
501 .tx_completion = aim_tx_completion,
502 };
503
mod_init(void)504 static int __init mod_init(void)
505 {
506 int err;
507
508 pr_info("init()\n");
509
510 INIT_LIST_HEAD(&channel_list);
511 spin_lock_init(&ch_list_lock);
512 ida_init(&minor_id);
513
514 err = alloc_chrdev_region(&aim_devno, 0, 50, "cdev");
515 if (err < 0)
516 goto dest_ida;
517 major = MAJOR(aim_devno);
518
519 aim_class = class_create(THIS_MODULE, "most_cdev_aim");
520 if (IS_ERR(aim_class)) {
521 pr_err("no udev support\n");
522 err = PTR_ERR(aim_class);
523 goto free_cdev;
524 }
525 err = most_register_aim(&cdev_aim);
526 if (err)
527 goto dest_class;
528 return 0;
529
530 dest_class:
531 class_destroy(aim_class);
532 free_cdev:
533 unregister_chrdev_region(aim_devno, 1);
534 dest_ida:
535 ida_destroy(&minor_id);
536 return err;
537 }
538
mod_exit(void)539 static void __exit mod_exit(void)
540 {
541 struct aim_channel *c, *tmp;
542
543 pr_info("exit module\n");
544
545 most_deregister_aim(&cdev_aim);
546
547 list_for_each_entry_safe(c, tmp, &channel_list, list) {
548 destroy_cdev(c);
549 kfree(c);
550 }
551 class_destroy(aim_class);
552 unregister_chrdev_region(aim_devno, 1);
553 ida_destroy(&minor_id);
554 }
555
556 module_init(mod_init);
557 module_exit(mod_exit);
558 MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
559 MODULE_LICENSE("GPL");
560 MODULE_DESCRIPTION("character device AIM for mostcore");
561