summaryrefslogtreecommitdiff
path: root/drivers/net/wwan/wwan_core.c
blob: cff04e532c1e0778800c0bb255f1a61bf20d8e59 (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
// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2021, Linaro Ltd <loic.poulain@linaro.org> */

#include <linux/err.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/idr.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/wwan.h>

#define WWAN_MAX_MINORS 256 /* 256 minors allowed with register_chrdev() */

static DEFINE_MUTEX(wwan_register_lock); /* WWAN device create|remove lock */
static DEFINE_IDA(minors); /* minors for WWAN port chardevs */
static DEFINE_IDA(wwan_dev_ids); /* for unique WWAN device IDs */
static struct class *wwan_class;
static int wwan_major;

#define to_wwan_dev(d) container_of(d, struct wwan_device, dev)
#define to_wwan_port(d) container_of(d, struct wwan_port, dev)

/* WWAN port flags */
#define WWAN_PORT_TX_OFF	0

/**
 * struct wwan_device - The structure that defines a WWAN device
 *
 * @id: WWAN device unique ID.
 * @dev: Underlying device.
 * @port_id: Current available port ID to pick.
 */
struct wwan_device {
	unsigned int id;
	struct device dev;
	atomic_t port_id;
};

/**
 * struct wwan_port - The structure that defines a WWAN port
 * @type: Port type
 * @start_count: Port start counter
 * @flags: Store port state and capabilities
 * @ops: Pointer to WWAN port operations
 * @ops_lock: Protect port ops
 * @dev: Underlying device
 * @rxq: Buffer inbound queue
 * @waitqueue: The waitqueue for port fops (read/write/poll)
 */
struct wwan_port {
	enum wwan_port_type type;
	unsigned int start_count;
	unsigned long flags;
	const struct wwan_port_ops *ops;
	struct mutex ops_lock; /* Serialize ops + protect against removal */
	struct device dev;
	struct sk_buff_head rxq;
	wait_queue_head_t waitqueue;
};

static void wwan_dev_destroy(struct device *dev)
{
	struct wwan_device *wwandev = to_wwan_dev(dev);

	ida_free(&wwan_dev_ids, wwandev->id);
	kfree(wwandev);
}

static const struct device_type wwan_dev_type = {
	.name    = "wwan_dev",
	.release = wwan_dev_destroy,
};

static int wwan_dev_parent_match(struct device *dev, const void *parent)
{
	return (dev->type == &wwan_dev_type && dev->parent == parent);
}

static struct wwan_device *wwan_dev_get_by_parent(struct device *parent)
{
	struct device *dev;

	dev = class_find_device(wwan_class, NULL, parent, wwan_dev_parent_match);
	if (!dev)
		return ERR_PTR(-ENODEV);

	return to_wwan_dev(dev);
}

/* This function allocates and registers a new WWAN device OR if a WWAN device
 * already exist for the given parent, it gets a reference and return it.
 * This function is not exported (for now), it is called indirectly via
 * wwan_create_port().
 */
static struct wwan_device *wwan_create_dev(struct device *parent)
{
	struct wwan_device *wwandev;
	int err, id;

	/* The 'find-alloc-register' operation must be protected against
	 * concurrent execution, a WWAN device is possibly shared between
	 * multiple callers or concurrently unregistered from wwan_remove_dev().
	 */
	mutex_lock(&wwan_register_lock);

	/* If wwandev already exists, return it */
	wwandev = wwan_dev_get_by_parent(parent);
	if (!IS_ERR(wwandev))
		goto done_unlock;

	id = ida_alloc(&wwan_dev_ids, GFP_KERNEL);
	if (id < 0)
		goto done_unlock;

	wwandev = kzalloc(sizeof(*wwandev), GFP_KERNEL);
	if (!wwandev) {
		ida_free(&wwan_dev_ids, id);
		goto done_unlock;
	}

	wwandev->dev.parent = parent;
	wwandev->dev.class = wwan_class;
	wwandev->dev.type = &wwan_dev_type;
	wwandev->id = id;
	dev_set_name(&wwandev->dev, "wwan%d", wwandev->id);

	err = device_register(&wwandev->dev);
	if (err) {
		put_device(&wwandev->dev);
		wwandev = NULL;
	}

done_unlock:
	mutex_unlock(&wwan_register_lock);

	return wwandev;
}

static int is_wwan_child(struct device *dev, void *data)
{
	return dev->class == wwan_class;
}

static void wwan_remove_dev(struct wwan_device *wwandev)
{
	int ret;

	/* Prevent concurrent picking from wwan_create_dev */
	mutex_lock(&wwan_register_lock);

	/* WWAN device is created and registered (get+add) along with its first
	 * child port, and subsequent port registrations only grab a reference
	 * (get). The WWAN device must then be unregistered (del+put) along with
	 * its latest port, and reference simply dropped (put) otherwise.
	 */
	ret = device_for_each_child(&wwandev->dev, NULL, is_wwan_child);
	if (!ret)
		device_unregister(&wwandev->dev);
	else
		put_device(&wwandev->dev);

	mutex_unlock(&wwan_register_lock);
}

/* ------- WWAN port management ------- */

static void wwan_port_destroy(struct device *dev)
{
	struct wwan_port *port = to_wwan_port(dev);

	ida_free(&minors, MINOR(port->dev.devt));
	skb_queue_purge(&port->rxq);
	mutex_destroy(&port->ops_lock);
	kfree(port);
}

static const struct device_type wwan_port_dev_type = {
	.name = "wwan_port",
	.release = wwan_port_destroy,
};

static int wwan_port_minor_match(struct device *dev, const void *minor)
{
	return (dev->type == &wwan_port_dev_type &&
		MINOR(dev->devt) == *(unsigned int *)minor);
}

static struct wwan_port *wwan_port_get_by_minor(unsigned int minor)
{
	struct device *dev;

	dev = class_find_device(wwan_class, NULL, &minor, wwan_port_minor_match);
	if (!dev)
		return ERR_PTR(-ENODEV);

	return to_wwan_port(dev);
}

/* Keep aligned with wwan_port_type enum */
static const char * const wwan_port_type_str[] = {
	"AT",
	"MBIM",
	"QMI",
	"QCDM",
	"FIREHOSE"
};

struct wwan_port *wwan_create_port(struct device *parent,
				   enum wwan_port_type type,
				   const struct wwan_port_ops *ops,
				   void *drvdata)
{
	struct wwan_device *wwandev;
	struct wwan_port *port;
	int minor, err = -ENOMEM;

	if (type >= WWAN_PORT_MAX || !ops)
		return ERR_PTR(-EINVAL);

	/* A port is always a child of a WWAN device, retrieve (allocate or
	 * pick) the WWAN device based on the provided parent device.
	 */
	wwandev = wwan_create_dev(parent);
	if (IS_ERR(wwandev))
		return ERR_CAST(wwandev);

	/* A port is exposed as character device, get a minor */
	minor = ida_alloc_range(&minors, 0, WWAN_MAX_MINORS - 1, GFP_KERNEL);
	if (minor < 0)
		goto error_wwandev_remove;

	port = kzalloc(sizeof(*port), GFP_KERNEL);
	if (!port) {
		ida_free(&minors, minor);
		goto error_wwandev_remove;
	}

	port->type = type;
	port->ops = ops;
	mutex_init(&port->ops_lock);
	skb_queue_head_init(&port->rxq);
	init_waitqueue_head(&port->waitqueue);

	port->dev.parent = &wwandev->dev;
	port->dev.class = wwan_class;
	port->dev.type = &wwan_port_dev_type;
	port->dev.devt = MKDEV(wwan_major, minor);
	dev_set_drvdata(&port->dev, drvdata);

	/* create unique name based on wwan device id, port index and type */
	dev_set_name(&port->dev, "wwan%up%u%s", wwandev->id,
		     atomic_inc_return(&wwandev->port_id),
		     wwan_port_type_str[port->type]);

	err = device_register(&port->dev);
	if (err)
		goto error_put_device;

	return port;

error_put_device:
	put_device(&port->dev);
error_wwandev_remove:
	wwan_remove_dev(wwandev);

	return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(wwan_create_port);

void wwan_remove_port(struct wwan_port *port)
{
	struct wwan_device *wwandev = to_wwan_dev(port->dev.parent);

	mutex_lock(&port->ops_lock);
	if (port->start_count)
		port->ops->stop(port);
	port->ops = NULL; /* Prevent any new port operations (e.g. from fops) */
	mutex_unlock(&port->ops_lock);

	wake_up_interruptible(&port->waitqueue);

	skb_queue_purge(&port->rxq);
	dev_set_drvdata(&port->dev, NULL);
	device_unregister(&port->dev);

	/* Release related wwan device */
	wwan_remove_dev(wwandev);
}
EXPORT_SYMBOL_GPL(wwan_remove_port);

void wwan_port_rx(struct wwan_port *port, struct sk_buff *skb)
{
	skb_queue_tail(&port->rxq, skb);
	wake_up_interruptible(&port->waitqueue);
}
EXPORT_SYMBOL_GPL(wwan_port_rx);

void wwan_port_txon(struct wwan_port *port)
{
	clear_bit(WWAN_PORT_TX_OFF, &port->flags);
	wake_up_interruptible(&port->waitqueue);
}
EXPORT_SYMBOL_GPL(wwan_port_txon);

void wwan_port_txoff(struct wwan_port *port)
{
	set_bit(WWAN_PORT_TX_OFF, &port->flags);
}
EXPORT_SYMBOL_GPL(wwan_port_txoff);

void *wwan_port_get_drvdata(struct wwan_port *port)
{
	return dev_get_drvdata(&port->dev);
}
EXPORT_SYMBOL_GPL(wwan_port_get_drvdata);

static int wwan_port_op_start(struct wwan_port *port)
{
	int ret = 0;

	mutex_lock(&port->ops_lock);
	if (!port->ops) { /* Port got unplugged */
		ret = -ENODEV;
		goto out_unlock;
	}

	/* If port is already started, don't start again */
	if (!port->start_count)
		ret = port->ops->start(port);

	if (!ret)
		port->start_count++;

out_unlock:
	mutex_unlock(&port->ops_lock);

	return ret;
}

static void wwan_port_op_stop(struct wwan_port *port)
{
	mutex_lock(&port->ops_lock);
	port->start_count--;
	if (port->ops && !port->start_count)
		port->ops->stop(port);
	mutex_unlock(&port->ops_lock);
}

static int wwan_port_op_tx(struct wwan_port *port, struct sk_buff *skb)
{
	int ret;

	mutex_lock(&port->ops_lock);
	if (!port->ops) { /* Port got unplugged */
		ret = -ENODEV;
		goto out_unlock;
	}

	ret = port->ops->tx(port, skb);

out_unlock:
	mutex_unlock(&port->ops_lock);

	return ret;
}

static bool is_read_blocked(struct wwan_port *port)
{
	return skb_queue_empty(&port->rxq) && port->ops;
}

static bool is_write_blocked(struct wwan_port *port)
{
	return test_bit(WWAN_PORT_TX_OFF, &port->flags) && port->ops;
}

static int wwan_wait_rx(struct wwan_port *port, bool nonblock)
{
	if (!is_read_blocked(port))
		return 0;

	if (nonblock)
		return -EAGAIN;

	if (wait_event_interruptible(port->waitqueue, !is_read_blocked(port)))
		return -ERESTARTSYS;

	return 0;
}

static int wwan_wait_tx(struct wwan_port *port, bool nonblock)
{
	if (!is_write_blocked(port))
		return 0;

	if (nonblock)
		return -EAGAIN;

	if (wait_event_interruptible(port->waitqueue, !is_write_blocked(port)))
		return -ERESTARTSYS;

	return 0;
}

static int wwan_port_fops_open(struct inode *inode, struct file *file)
{
	struct wwan_port *port;
	int err = 0;

	port = wwan_port_get_by_minor(iminor(inode));
	if (IS_ERR(port))
		return PTR_ERR(port);

	file->private_data = port;
	stream_open(inode, file);

	err = wwan_port_op_start(port);
	if (err)
		put_device(&port->dev);

	return err;
}

static int wwan_port_fops_release(struct inode *inode, struct file *filp)
{
	struct wwan_port *port = filp->private_data;

	wwan_port_op_stop(port);
	put_device(&port->dev);

	return 0;
}

static ssize_t wwan_port_fops_read(struct file *filp, char __user *buf,
				   size_t count, loff_t *ppos)
{
	struct wwan_port *port = filp->private_data;
	struct sk_buff *skb;
	size_t copied;
	int ret;

	ret = wwan_wait_rx(port, !!(filp->f_flags & O_NONBLOCK));
	if (ret)
		return ret;

	skb = skb_dequeue(&port->rxq);
	if (!skb)
		return -EIO;

	copied = min_t(size_t, count, skb->len);
	if (copy_to_user(buf, skb->data, copied)) {
		kfree_skb(skb);
		return -EFAULT;
	}
	skb_pull(skb, copied);

	/* skb is not fully consumed, keep it in the queue */
	if (skb->len)
		skb_queue_head(&port->rxq, skb);
	else
		consume_skb(skb);

	return copied;
}

static ssize_t wwan_port_fops_write(struct file *filp, const char __user *buf,
				    size_t count, loff_t *offp)
{
	struct wwan_port *port = filp->private_data;
	struct sk_buff *skb;
	int ret;

	ret = wwan_wait_tx(port, !!(filp->f_flags & O_NONBLOCK));
	if (ret)
		return ret;

	skb = alloc_skb(count, GFP_KERNEL);
	if (!skb)
		return -ENOMEM;

	if (copy_from_user(skb_put(skb, count), buf, count)) {
		kfree_skb(skb);
		return -EFAULT;
	}

	ret = wwan_port_op_tx(port, skb);
	if (ret) {
		kfree_skb(skb);
		return ret;
	}

	return count;
}

static __poll_t wwan_port_fops_poll(struct file *filp, poll_table *wait)
{
	struct wwan_port *port = filp->private_data;
	__poll_t mask = 0;

	poll_wait(filp, &port->waitqueue, wait);

	if (!is_write_blocked(port))
		mask |= EPOLLOUT | EPOLLWRNORM;
	if (!is_read_blocked(port))
		mask |= EPOLLIN | EPOLLRDNORM;
	if (!port->ops)
		mask |= EPOLLHUP | EPOLLERR;

	return mask;
}

static const struct file_operations wwan_port_fops = {
	.owner = THIS_MODULE,
	.open = wwan_port_fops_open,
	.release = wwan_port_fops_release,
	.read = wwan_port_fops_read,
	.write = wwan_port_fops_write,
	.poll = wwan_port_fops_poll,
	.llseek = noop_llseek,
};

static int __init wwan_init(void)
{
	wwan_class = class_create(THIS_MODULE, "wwan");
	if (IS_ERR(wwan_class))
		return PTR_ERR(wwan_class);

	/* chrdev used for wwan ports */
	wwan_major = register_chrdev(0, "wwan_port", &wwan_port_fops);
	if (wwan_major < 0) {
		class_destroy(wwan_class);
		return wwan_major;
	}

	return 0;
}

static void __exit wwan_exit(void)
{
	unregister_chrdev(wwan_major, "wwan_port");
	class_destroy(wwan_class);
}

module_init(wwan_init);
module_exit(wwan_exit);

MODULE_AUTHOR("Loic Poulain <loic.poulain@linaro.org>");
MODULE_DESCRIPTION("WWAN core");
MODULE_LICENSE("GPL v2");