summaryrefslogtreecommitdiffstats
path: root/driver/aim-cdev/cdev.c
blob: 48d97bf693fd9218a3958d6eace0fcc37d7e6186 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
/*
 * cdev.c - Application interfacing module for character devices
 *
 * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * This file is licensed under GPLv2.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/poll.h>
#include <linux/kfifo.h>
#include <linux/uaccess.h>
#include <linux/idr.h>
#include "mostcore.h"

static dev_t aim_devno;
static struct class *aim_class;
static struct ida minor_id;
static unsigned int major;
static struct most_aim cdev_aim;

struct aim_channel {
	wait_queue_head_t wq;
	spinlock_t unlink;	/* synchronization lock to unlink channels */
	struct cdev cdev;
	struct device *dev;
	struct mutex io_mutex;
	struct most_interface *iface;
	struct most_channel_config *cfg;
	unsigned int channel_id;
	dev_t devno;
	size_t mbo_offs;
	DECLARE_KFIFO_PTR(fifo, typeof(struct mbo *));
	int access_ref;
	struct list_head list;
};

#define to_channel(d) container_of(d, struct aim_channel, cdev)
static struct list_head channel_list;
static spinlock_t ch_list_lock;

static inline bool ch_has_mbo(struct aim_channel *c)
{
	return channel_has_mbo(c->iface, c->channel_id, &cdev_aim) > 0;
}

static inline bool ch_get_mbo(struct aim_channel *c, struct mbo **mbo)
{
	*mbo = most_get_mbo(c->iface, c->channel_id, &cdev_aim);
	return *mbo;
}

static struct aim_channel *get_channel(struct most_interface *iface, int id)
{
	struct aim_channel *c, *tmp;
	unsigned long flags;
	int found_channel = 0;

	spin_lock_irqsave(&ch_list_lock, flags);
	list_for_each_entry_safe(c, tmp, &channel_list, list) {
		if ((c->iface == iface) && (c->channel_id == id)) {
			found_channel = 1;
			break;
		}
	}
	spin_unlock_irqrestore(&ch_list_lock, flags);
	if (!found_channel)
		return NULL;
	return c;
}

static void stop_channel(struct aim_channel *c)
{
	struct mbo *mbo;

	while (kfifo_out((struct kfifo *)&c->fifo, &mbo, 1))
		most_put_mbo(mbo);
	most_stop_channel(c->iface, c->channel_id, &cdev_aim);
}

static void destroy_cdev(struct aim_channel *c)
{
	unsigned long flags;

	device_destroy(aim_class, c->devno);
	cdev_del(&c->cdev);
	kfifo_free(&c->fifo);
	spin_lock_irqsave(&ch_list_lock, flags);
	list_del(&c->list);
	spin_unlock_irqrestore(&ch_list_lock, flags);
	ida_simple_remove(&minor_id, MINOR(c->devno));
}

/**
 * aim_open - implements the syscall to open the device
 * @inode: inode pointer
 * @filp: file pointer
 *
 * This stores the channel pointer in the private data field of
 * the file structure and activates the channel within the core.
 */
static int aim_open(struct inode *inode, struct file *filp)
{
	struct aim_channel *c;
	int ret;

	c = to_channel(inode->i_cdev);
	filp->private_data = c;

	if (((c->cfg->direction == MOST_CH_RX) &&
	     ((filp->f_flags & O_ACCMODE) != O_RDONLY)) ||
	     ((c->cfg->direction == MOST_CH_TX) &&
		((filp->f_flags & O_ACCMODE) != O_WRONLY))) {
		pr_info("WARN: Access flags mismatch\n");
		return -EACCES;
	}

	mutex_lock(&c->io_mutex);
	if (!c->dev) {
		pr_info("WARN: Device is destroyed\n");
		mutex_unlock(&c->io_mutex);
		return -ENODEV;
	}

	if (c->access_ref) {
		pr_info("WARN: Device is busy\n");
		mutex_unlock(&c->io_mutex);
		return -EBUSY;
	}

	c->mbo_offs = 0;
	ret = most_start_channel(c->iface, c->channel_id, &cdev_aim);
	if (!ret)
		c->access_ref = 1;
	mutex_unlock(&c->io_mutex);
	return ret;
}

/**
 * aim_close - implements the syscall to close the device
 * @inode: inode pointer
 * @filp: file pointer
 *
 * This stops the channel within the core.
 */
static int aim_close(struct inode *inode, struct file *filp)
{
	struct aim_channel *c = to_channel(inode->i_cdev);

	mutex_lock(&c->io_mutex);
	spin_lock(&c->unlink);
	c->access_ref = 0;
	spin_unlock(&c->unlink);
	if (c->dev) {
		stop_channel(c);
		mutex_unlock(&c->io_mutex);
	} else {
		destroy_cdev(c);
		mutex_unlock(&c->io_mutex);
		kfree(c);
	}
	return 0;
}

/**
 * aim_write - implements the syscall to write to the device
 * @filp: file pointer
 * @buf: pointer to user buffer
 * @count: number of bytes to write
 * @offset: offset from where to start writing
 */
static ssize_t aim_write(struct file *filp, const char __user *buf,
			 size_t count, loff_t *offset)
{
	int ret;
	size_t actual_len;
	size_t max_len;
	struct mbo *mbo = NULL;
	struct aim_channel *c = filp->private_data;

	mutex_lock(&c->io_mutex);
	while (c->dev && !ch_get_mbo(c, &mbo)) {
		mutex_unlock(&c->io_mutex);

		if ((filp->f_flags & O_NONBLOCK))
			return -EAGAIN;
		if (wait_event_interruptible(c->wq, ch_has_mbo(c) || !c->dev))
			return -ERESTARTSYS;
		mutex_lock(&c->io_mutex);
	}

	if (unlikely(!c->dev)) {
		ret = -ENODEV;
		goto unlock;
	}

	max_len = c->cfg->buffer_size;
	actual_len = min(count, max_len);
	mbo->buffer_length = actual_len;

	if (copy_from_user(mbo->virt_address, buf, mbo->buffer_length)) {
		ret = -EFAULT;
		goto put_mbo;
	}

	ret = most_submit_mbo(mbo);
	if (ret)
		goto put_mbo;

	mutex_unlock(&c->io_mutex);
	return actual_len;
put_mbo:
	most_put_mbo(mbo);
unlock:
	mutex_unlock(&c->io_mutex);
	return ret;
}

/**
 * aim_read - implements the syscall to read from the device
 * @filp: file pointer
 * @buf: pointer to user buffer
 * @count: number of bytes to read
 * @offset: offset from where to start reading
 */
static ssize_t
aim_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
{
	size_t to_copy, not_copied, copied;
	struct mbo *mbo;
	struct aim_channel *c = filp->private_data;

	mutex_lock(&c->io_mutex);
	while (c->dev && !kfifo_peek(&c->fifo, &mbo)) {
		mutex_unlock(&c->io_mutex);
		if (filp->f_flags & O_NONBLOCK)
			return -EAGAIN;
		if (wait_event_interruptible(c->wq,
					     (!kfifo_is_empty(&c->fifo) ||
					      (!c->dev))))
			return -ERESTARTSYS;
		mutex_lock(&c->io_mutex);
	}

	/* make sure we don't submit to gone devices */
	if (unlikely(!c->dev)) {
		mutex_unlock(&c->io_mutex);
		return -ENODEV;
	}

	to_copy = min_t(size_t,
			count,
			mbo->processed_length - c->mbo_offs);

	not_copied = copy_to_user(buf,
				  mbo->virt_address + c->mbo_offs,
				  to_copy);

	copied = to_copy - not_copied;

	c->mbo_offs += copied;
	if (c->mbo_offs >= mbo->processed_length) {
		kfifo_skip(&c->fifo);
		most_put_mbo(mbo);
		c->mbo_offs = 0;
	}
	mutex_unlock(&c->io_mutex);
	return copied;
}

static unsigned int aim_poll(struct file *filp, poll_table *wait)
{
	struct aim_channel *c = filp->private_data;
	unsigned int mask = 0;

	poll_wait(filp, &c->wq, wait);

	if (c->cfg->direction == MOST_CH_RX) {
		if (!kfifo_is_empty(&c->fifo))
			mask |= POLLIN | POLLRDNORM;
	} else {
		if (ch_has_mbo(c))
			mask |= POLLOUT | POLLWRNORM;
	}
	return mask;
}

/**
 * Initialization of struct file_operations
 */
static const struct file_operations channel_fops = {
	.owner = THIS_MODULE,
	.read = aim_read,
	.write = aim_write,
	.open = aim_open,
	.release = aim_close,
	.poll = aim_poll,
};

/**
 * aim_disconnect_channel - disconnect a channel
 * @iface: pointer to interface instance
 * @channel_id: channel index
 *
 * This frees allocated memory and removes the cdev that represents this
 * channel in user space.
 */
static int aim_disconnect_channel(struct most_interface *iface, int channel_id)
{
	struct aim_channel *c;

	if (!iface) {
		pr_info("Bad interface pointer\n");
		return -EINVAL;
	}

	c = get_channel(iface, channel_id);
	if (!c)
		return -ENXIO;

	mutex_lock(&c->io_mutex);
	spin_lock(&c->unlink);
	c->dev = NULL;
	spin_unlock(&c->unlink);
	if (c->access_ref) {
		stop_channel(c);
		wake_up_interruptible(&c->wq);
		mutex_unlock(&c->io_mutex);
	} else {
		destroy_cdev(c);
		mutex_unlock(&c->io_mutex);
		kfree(c);
	}
	return 0;
}

/**
 * aim_rx_completion - completion handler for rx channels
 * @mbo: pointer to buffer object that has completed
 *
 * This searches for the channel linked to this MBO and stores it in the local
 * fifo buffer.
 */
static int aim_rx_completion(struct mbo *mbo)
{
	struct aim_channel *c;

	if (!mbo)
		return -EINVAL;

	c = get_channel(mbo->ifp, mbo->hdm_channel_id);
	if (!c)
		return -ENXIO;

	spin_lock(&c->unlink);
	if (!c->access_ref || !c->dev) {
		spin_unlock(&c->unlink);
		return -ENODEV;
	}
	kfifo_in(&c->fifo, &mbo, 1);
	spin_unlock(&c->unlink);
#ifdef DEBUG_MESG
	if (kfifo_is_full(&c->fifo))
		pr_info("WARN: Fifo is full\n");
#endif
	wake_up_interruptible(&c->wq);
	return 0;
}

/**
 * aim_tx_completion - completion handler for tx channels
 * @iface: pointer to interface instance
 * @channel_id: channel index/ID
 *
 * This wakes sleeping processes in the wait-queue.
 */
static int aim_tx_completion(struct most_interface *iface, int channel_id)
{
	struct aim_channel *c;

	if (!iface) {
		pr_info("Bad interface pointer\n");
		return -EINVAL;
	}
	if ((channel_id < 0) || (channel_id >= iface->num_channels)) {
		pr_info("Channel ID out of range\n");
		return -EINVAL;
	}

	c = get_channel(iface, channel_id);
	if (!c)
		return -ENXIO;
	wake_up_interruptible(&c->wq);
	return 0;
}

/**
 * aim_probe - probe function of the driver module
 * @iface: pointer to interface instance
 * @channel_id: channel index/ID
 * @cfg: pointer to actual channel configuration
 * @parent: pointer to kobject (needed for sysfs hook-up)
 * @name: name of the device to be created
 *
 * This allocates achannel object and creates the device node in /dev
 *
 * Returns 0 on success or error code otherwise.
 */
static int aim_probe(struct most_interface *iface, int channel_id,
		     struct most_channel_config *cfg,
		     struct kobject *parent, char *name)
{
	struct aim_channel *c;
	unsigned long cl_flags;
	int retval;
	int current_minor;

	if ((!iface) || (!cfg) || (!parent) || (!name)) {
		pr_info("Probing AIM with bad arguments");
		return -EINVAL;
	}
	c = get_channel(iface, channel_id);
	if (c)
		return -EEXIST;

	current_minor = ida_simple_get(&minor_id, 0, 0, GFP_KERNEL);
	if (current_minor < 0)
		return current_minor;

	c = kzalloc(sizeof(*c), GFP_KERNEL);
	if (!c) {
		retval = -ENOMEM;
		goto error_alloc_channel;
	}

	c->devno = MKDEV(major, current_minor);
	cdev_init(&c->cdev, &channel_fops);
	c->cdev.owner = THIS_MODULE;
	cdev_add(&c->cdev, c->devno, 1);
	c->iface = iface;
	c->cfg = cfg;
	c->channel_id = channel_id;
	c->access_ref = 0;
	spin_lock_init(&c->unlink);
	INIT_KFIFO(c->fifo);
	retval = kfifo_alloc(&c->fifo, cfg->num_buffers, GFP_KERNEL);
	if (retval) {
		pr_info("failed to alloc channel kfifo");
		goto error_alloc_kfifo;
	}
	init_waitqueue_head(&c->wq);
	mutex_init(&c->io_mutex);
	spin_lock_irqsave(&ch_list_lock, cl_flags);
	list_add_tail(&c->list, &channel_list);
	spin_unlock_irqrestore(&ch_list_lock, cl_flags);
	c->dev = device_create(aim_class,
				     NULL,
				     c->devno,
				     NULL,
				     "%s", name);

	if (IS_ERR(c->dev)) {
		retval = PTR_ERR(c->dev);
		pr_info("failed to create new device node %s\n", name);
		goto error_create_device;
	}
	kobject_uevent(&c->dev->kobj, KOBJ_ADD);
	return 0;

error_create_device:
	kfifo_free(&c->fifo);
	list_del(&c->list);
error_alloc_kfifo:
	cdev_del(&c->cdev);
	kfree(c);
error_alloc_channel:
	ida_simple_remove(&minor_id, current_minor);
	return retval;
}

static struct most_aim cdev_aim = {
	.name = "cdev",
	.probe_channel = aim_probe,
	.disconnect_channel = aim_disconnect_channel,
	.rx_completion = aim_rx_completion,
	.tx_completion = aim_tx_completion,
};

static int __init mod_init(void)
{
	int err;

	pr_info("init()\n");

	INIT_LIST_HEAD(&channel_list);
	spin_lock_init(&ch_list_lock);
	ida_init(&minor_id);

	err = alloc_chrdev_region(&aim_devno, 0, 50, "cdev");
	if (err < 0)
		return err;
	major = MAJOR(aim_devno);

	aim_class = class_create(THIS_MODULE, "most_cdev_aim");
	if (IS_ERR(aim_class)) {
		pr_err("no udev support\n");
		err = PTR_ERR(aim_class);
		goto free_cdev;
	}
	err = most_register_aim(&cdev_aim); 
	if (err)
		goto dest_class;
	return 0;

dest_class:
	class_destroy(aim_class);
free_cdev:
	unregister_chrdev_region(aim_devno, 1);
	return err;
}

static void __exit mod_exit(void)
{
	struct aim_channel *c, *tmp;

	pr_info("exit module\n");

	most_deregister_aim(&cdev_aim);

	list_for_each_entry_safe(c, tmp, &channel_list, list) {
		destroy_cdev(c);
		kfree(c);
	}
	class_destroy(aim_class);
	unregister_chrdev_region(aim_devno, 1);
	ida_destroy(&minor_id);
}

module_init(mod_init);
module_exit(mod_exit);
MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("character device AIM for mostcore");