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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * WWAN device simulator for WWAN framework testing.
4 *
5 * Copyright (c) 2021, Sergey Ryazanov <ryazanov.s.a@gmail.com>
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/slab.h>
13#include <linux/device.h>
14#include <linux/spinlock.h>
15#include <linux/list.h>
16#include <linux/skbuff.h>
17#include <linux/netdevice.h>
18#include <linux/wwan.h>
19#include <linux/debugfs.h>
20#include <linux/workqueue.h>
21
22#include <net/arp.h>
23
24static int wwan_hwsim_devsnum = 2;
25module_param_named(devices, wwan_hwsim_devsnum, int, 0444);
26MODULE_PARM_DESC(devices, "Number of simulated devices");
27
28static struct class *wwan_hwsim_class;
29
30static struct dentry *wwan_hwsim_debugfs_topdir;
31static struct dentry *wwan_hwsim_debugfs_devcreate;
32
33static DEFINE_SPINLOCK(wwan_hwsim_devs_lock);
34static LIST_HEAD(wwan_hwsim_devs);
35static unsigned int wwan_hwsim_dev_idx;
36static struct workqueue_struct *wwan_wq;
37
38struct wwan_hwsim_dev {
39 struct list_head list;
40 unsigned int id;
41 struct device dev;
42 struct work_struct del_work;
43 struct dentry *debugfs_topdir;
44 struct dentry *debugfs_portcreate;
45 spinlock_t ports_lock; /* Serialize ports creation/deletion */
46 unsigned int port_idx;
47 struct list_head ports;
48};
49
50struct wwan_hwsim_port {
51 struct list_head list;
52 unsigned int id;
53 struct wwan_hwsim_dev *dev;
54 struct wwan_port *wwan;
55 struct work_struct del_work;
56 struct dentry *debugfs_topdir;
57 enum { /* AT command parser state */
58 AT_PARSER_WAIT_A,
59 AT_PARSER_WAIT_T,
60 AT_PARSER_WAIT_TERM,
61 AT_PARSER_SKIP_LINE,
62 } pstate;
63};
64
65static const struct file_operations wwan_hwsim_debugfs_portdestroy_fops;
66static const struct file_operations wwan_hwsim_debugfs_portcreate_fops;
67static const struct file_operations wwan_hwsim_debugfs_devdestroy_fops;
68static void wwan_hwsim_port_del_work(struct work_struct *work);
69static void wwan_hwsim_dev_del_work(struct work_struct *work);
70
71static netdev_tx_t wwan_hwsim_netdev_xmit(struct sk_buff *skb,
72 struct net_device *ndev)
73{
74 ndev->stats.tx_packets++;
75 ndev->stats.tx_bytes += skb->len;
76 consume_skb(skb);
77 return NETDEV_TX_OK;
78}
79
80static const struct net_device_ops wwan_hwsim_netdev_ops = {
81 .ndo_start_xmit = wwan_hwsim_netdev_xmit,
82};
83
84static void wwan_hwsim_netdev_setup(struct net_device *ndev)
85{
86 ndev->netdev_ops = &wwan_hwsim_netdev_ops;
87 ndev->needs_free_netdev = true;
88
89 ndev->mtu = ETH_DATA_LEN;
90 ndev->min_mtu = ETH_MIN_MTU;
91 ndev->max_mtu = ETH_MAX_MTU;
92
93 ndev->type = ARPHRD_NONE;
94 ndev->flags = IFF_POINTOPOINT | IFF_NOARP;
95}
96
97static const struct wwan_ops wwan_hwsim_wwan_rtnl_ops = {
98 .priv_size = 0, /* No private data */
99 .setup = wwan_hwsim_netdev_setup,
100};
101
102static int wwan_hwsim_port_start(struct wwan_port *wport)
103{
104 struct wwan_hwsim_port *port = wwan_port_get_drvdata(wport);
105
106 port->pstate = AT_PARSER_WAIT_A;
107
108 return 0;
109}
110
111static void wwan_hwsim_port_stop(struct wwan_port *wport)
112{
113}
114
115/* Implements a minimalistic AT commands parser that echo input back and
116 * reply with 'OK' to each input command. See AT command protocol details in the
117 * ITU-T V.250 recomendations document.
118 *
119 * Be aware that this processor is not fully V.250 compliant.
120 */
121static int wwan_hwsim_port_tx(struct wwan_port *wport, struct sk_buff *in)
122{
123 struct wwan_hwsim_port *port = wwan_port_get_drvdata(wport);
124 struct sk_buff *out;
125 int i, n, s;
126
127 /* Estimate a max possible number of commands by counting the number of
128 * termination chars (S3 param, CR by default). And then allocate the
129 * output buffer that will be enough to fit the echo and result codes of
130 * all commands.
131 */
132 for (i = 0, n = 0; i < in->len; ++i)
133 if (in->data[i] == '\r')
134 n++;
135 n = in->len + n * (2 + 2 + 2); /* Output buffer size */
136 out = alloc_skb(n, GFP_KERNEL);
137 if (!out)
138 return -ENOMEM;
139
140 for (i = 0, s = 0; i < in->len; ++i) {
141 char c = in->data[i];
142
143 if (port->pstate == AT_PARSER_WAIT_A) {
144 if (c == 'A' || c == 'a')
145 port->pstate = AT_PARSER_WAIT_T;
146 else if (c != '\n') /* Ignore formating char */
147 port->pstate = AT_PARSER_SKIP_LINE;
148 } else if (port->pstate == AT_PARSER_WAIT_T) {
149 if (c == 'T' || c == 't')
150 port->pstate = AT_PARSER_WAIT_TERM;
151 else
152 port->pstate = AT_PARSER_SKIP_LINE;
153 } else if (port->pstate == AT_PARSER_WAIT_TERM) {
154 if (c != '\r')
155 continue;
156 /* Consume the trailing formatting char as well */
157 if ((i + 1) < in->len && in->data[i + 1] == '\n')
158 i++;
159 n = i - s + 1;
160 skb_put_data(out, &in->data[s], n);/* Echo */
161 skb_put_data(out, "\r\nOK\r\n", 6);
162 s = i + 1;
163 port->pstate = AT_PARSER_WAIT_A;
164 } else if (port->pstate == AT_PARSER_SKIP_LINE) {
165 if (c != '\r')
166 continue;
167 port->pstate = AT_PARSER_WAIT_A;
168 }
169 }
170
171 if (i > s) {
172 /* Echo the processed portion of a not yet completed command */
173 n = i - s;
174 skb_put_data(out, &in->data[s], n);
175 }
176
177 consume_skb(in);
178
179 wwan_port_rx(wport, out);
180
181 return 0;
182}
183
184static const struct wwan_port_ops wwan_hwsim_port_ops = {
185 .start = wwan_hwsim_port_start,
186 .stop = wwan_hwsim_port_stop,
187 .tx = wwan_hwsim_port_tx,
188};
189
190static struct wwan_hwsim_port *wwan_hwsim_port_new(struct wwan_hwsim_dev *dev)
191{
192 struct wwan_hwsim_port *port;
193 char name[0x10];
194 int err;
195
196 port = kzalloc(sizeof(*port), GFP_KERNEL);
197 if (!port)
198 return ERR_PTR(-ENOMEM);
199
200 port->dev = dev;
201
202 spin_lock(&dev->ports_lock);
203 port->id = dev->port_idx++;
204 spin_unlock(&dev->ports_lock);
205
206 port->wwan = wwan_create_port(&dev->dev, WWAN_PORT_AT,
207 &wwan_hwsim_port_ops,
208 NULL, port);
209 if (IS_ERR(port->wwan)) {
210 err = PTR_ERR(port->wwan);
211 goto err_free_port;
212 }
213
214 INIT_WORK(&port->del_work, wwan_hwsim_port_del_work);
215
216 snprintf(name, sizeof(name), "port%u", port->id);
217 port->debugfs_topdir = debugfs_create_dir(name, dev->debugfs_topdir);
218 debugfs_create_file("destroy", 0200, port->debugfs_topdir, port,
219 &wwan_hwsim_debugfs_portdestroy_fops);
220
221 return port;
222
223err_free_port:
224 kfree(port);
225
226 return ERR_PTR(err);
227}
228
229static void wwan_hwsim_port_del(struct wwan_hwsim_port *port)
230{
231 debugfs_remove(port->debugfs_topdir);
232
233 /* Make sure that there is no pending deletion work */
234 if (current_work() != &port->del_work)
235 cancel_work_sync(&port->del_work);
236
237 wwan_remove_port(port->wwan);
238 kfree(port);
239}
240
241static void wwan_hwsim_port_del_work(struct work_struct *work)
242{
243 struct wwan_hwsim_port *port =
244 container_of(work, typeof(*port), del_work);
245 struct wwan_hwsim_dev *dev = port->dev;
246
247 spin_lock(&dev->ports_lock);
248 if (list_empty(&port->list)) {
249 /* Someone else deleting port at the moment */
250 spin_unlock(&dev->ports_lock);
251 return;
252 }
253 list_del_init(&port->list);
254 spin_unlock(&dev->ports_lock);
255
256 wwan_hwsim_port_del(port);
257}
258
259static void wwan_hwsim_dev_release(struct device *sysdev)
260{
261 struct wwan_hwsim_dev *dev = container_of(sysdev, typeof(*dev), dev);
262
263 kfree(dev);
264}
265
266static struct wwan_hwsim_dev *wwan_hwsim_dev_new(void)
267{
268 struct wwan_hwsim_dev *dev;
269 int err;
270
271 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
272 if (!dev)
273 return ERR_PTR(-ENOMEM);
274
275 spin_lock(&wwan_hwsim_devs_lock);
276 dev->id = wwan_hwsim_dev_idx++;
277 spin_unlock(&wwan_hwsim_devs_lock);
278
279 dev->dev.release = wwan_hwsim_dev_release;
280 dev->dev.class = wwan_hwsim_class;
281 dev_set_name(&dev->dev, "hwsim%u", dev->id);
282
283 spin_lock_init(&dev->ports_lock);
284 INIT_LIST_HEAD(&dev->ports);
285
286 err = device_register(&dev->dev);
287 if (err)
288 goto err_free_dev;
289
290 INIT_WORK(&dev->del_work, wwan_hwsim_dev_del_work);
291
292 err = wwan_register_ops(&dev->dev, &wwan_hwsim_wwan_rtnl_ops, dev, 1);
293 if (err)
294 goto err_unreg_dev;
295
296 dev->debugfs_topdir = debugfs_create_dir(dev_name(&dev->dev),
297 wwan_hwsim_debugfs_topdir);
298 debugfs_create_file("destroy", 0200, dev->debugfs_topdir, dev,
299 &wwan_hwsim_debugfs_devdestroy_fops);
300 dev->debugfs_portcreate =
301 debugfs_create_file("portcreate", 0200,
302 dev->debugfs_topdir, dev,
303 &wwan_hwsim_debugfs_portcreate_fops);
304
305 return dev;
306
307err_unreg_dev:
308 device_unregister(&dev->dev);
309 /* Memory will be freed in the device release callback */
310
311 return ERR_PTR(err);
312
313err_free_dev:
314 put_device(&dev->dev);
315
316 return ERR_PTR(err);
317}
318
319static void wwan_hwsim_dev_del(struct wwan_hwsim_dev *dev)
320{
321 debugfs_remove(dev->debugfs_portcreate); /* Avoid new ports */
322
323 spin_lock(&dev->ports_lock);
324 while (!list_empty(&dev->ports)) {
325 struct wwan_hwsim_port *port;
326
327 port = list_first_entry(&dev->ports, struct wwan_hwsim_port,
328 list);
329 list_del_init(&port->list);
330 spin_unlock(&dev->ports_lock);
331 wwan_hwsim_port_del(port);
332 spin_lock(&dev->ports_lock);
333 }
334 spin_unlock(&dev->ports_lock);
335
336 debugfs_remove(dev->debugfs_topdir);
337
338 /* This will remove all child netdev(s) */
339 wwan_unregister_ops(&dev->dev);
340
341 /* Make sure that there is no pending deletion work */
342 if (current_work() != &dev->del_work)
343 cancel_work_sync(&dev->del_work);
344
345 device_unregister(&dev->dev);
346 /* Memory will be freed in the device release callback */
347}
348
349static void wwan_hwsim_dev_del_work(struct work_struct *work)
350{
351 struct wwan_hwsim_dev *dev = container_of(work, typeof(*dev), del_work);
352
353 spin_lock(&wwan_hwsim_devs_lock);
354 if (list_empty(&dev->list)) {
355 /* Someone else deleting device at the moment */
356 spin_unlock(&wwan_hwsim_devs_lock);
357 return;
358 }
359 list_del_init(&dev->list);
360 spin_unlock(&wwan_hwsim_devs_lock);
361
362 wwan_hwsim_dev_del(dev);
363}
364
365static ssize_t wwan_hwsim_debugfs_portdestroy_write(struct file *file,
366 const char __user *usrbuf,
367 size_t count, loff_t *ppos)
368{
369 struct wwan_hwsim_port *port = file->private_data;
370
371 /* We can not delete port here since it will cause a deadlock due to
372 * waiting this callback to finish in the debugfs_remove() call. So,
373 * use workqueue.
374 */
375 queue_work(wwan_wq, &port->del_work);
376
377 return count;
378}
379
380static const struct file_operations wwan_hwsim_debugfs_portdestroy_fops = {
381 .write = wwan_hwsim_debugfs_portdestroy_write,
382 .open = simple_open,
383 .llseek = noop_llseek,
384};
385
386static ssize_t wwan_hwsim_debugfs_portcreate_write(struct file *file,
387 const char __user *usrbuf,
388 size_t count, loff_t *ppos)
389{
390 struct wwan_hwsim_dev *dev = file->private_data;
391 struct wwan_hwsim_port *port;
392
393 port = wwan_hwsim_port_new(dev);
394 if (IS_ERR(port))
395 return PTR_ERR(port);
396
397 spin_lock(&dev->ports_lock);
398 list_add_tail(&port->list, &dev->ports);
399 spin_unlock(&dev->ports_lock);
400
401 return count;
402}
403
404static const struct file_operations wwan_hwsim_debugfs_portcreate_fops = {
405 .write = wwan_hwsim_debugfs_portcreate_write,
406 .open = simple_open,
407 .llseek = noop_llseek,
408};
409
410static ssize_t wwan_hwsim_debugfs_devdestroy_write(struct file *file,
411 const char __user *usrbuf,
412 size_t count, loff_t *ppos)
413{
414 struct wwan_hwsim_dev *dev = file->private_data;
415
416 /* We can not delete device here since it will cause a deadlock due to
417 * waiting this callback to finish in the debugfs_remove() call. So,
418 * use workqueue.
419 */
420 queue_work(wwan_wq, &dev->del_work);
421
422 return count;
423}
424
425static const struct file_operations wwan_hwsim_debugfs_devdestroy_fops = {
426 .write = wwan_hwsim_debugfs_devdestroy_write,
427 .open = simple_open,
428 .llseek = noop_llseek,
429};
430
431static ssize_t wwan_hwsim_debugfs_devcreate_write(struct file *file,
432 const char __user *usrbuf,
433 size_t count, loff_t *ppos)
434{
435 struct wwan_hwsim_dev *dev;
436
437 dev = wwan_hwsim_dev_new();
438 if (IS_ERR(dev))
439 return PTR_ERR(dev);
440
441 spin_lock(&wwan_hwsim_devs_lock);
442 list_add_tail(&dev->list, &wwan_hwsim_devs);
443 spin_unlock(&wwan_hwsim_devs_lock);
444
445 return count;
446}
447
448static const struct file_operations wwan_hwsim_debugfs_devcreate_fops = {
449 .write = wwan_hwsim_debugfs_devcreate_write,
450 .open = simple_open,
451 .llseek = noop_llseek,
452};
453
454static int __init wwan_hwsim_init_devs(void)
455{
456 struct wwan_hwsim_dev *dev;
457 int i, j;
458
459 for (i = 0; i < wwan_hwsim_devsnum; ++i) {
460 dev = wwan_hwsim_dev_new();
461 if (IS_ERR(dev))
462 return PTR_ERR(dev);
463
464 spin_lock(&wwan_hwsim_devs_lock);
465 list_add_tail(&dev->list, &wwan_hwsim_devs);
466 spin_unlock(&wwan_hwsim_devs_lock);
467
468 /* Create a couple of ports per each device to accelerate
469 * the simulator readiness time.
470 */
471 for (j = 0; j < 2; ++j) {
472 struct wwan_hwsim_port *port;
473
474 port = wwan_hwsim_port_new(dev);
475 if (IS_ERR(port))
476 return PTR_ERR(port);
477
478 spin_lock(&dev->ports_lock);
479 list_add_tail(&port->list, &dev->ports);
480 spin_unlock(&dev->ports_lock);
481 }
482 }
483
484 return 0;
485}
486
487static void wwan_hwsim_free_devs(void)
488{
489 struct wwan_hwsim_dev *dev;
490
491 spin_lock(&wwan_hwsim_devs_lock);
492 while (!list_empty(&wwan_hwsim_devs)) {
493 dev = list_first_entry(&wwan_hwsim_devs, struct wwan_hwsim_dev,
494 list);
495 list_del_init(&dev->list);
496 spin_unlock(&wwan_hwsim_devs_lock);
497 wwan_hwsim_dev_del(dev);
498 spin_lock(&wwan_hwsim_devs_lock);
499 }
500 spin_unlock(&wwan_hwsim_devs_lock);
501}
502
503static int __init wwan_hwsim_init(void)
504{
505 int err;
506
507 if (wwan_hwsim_devsnum < 0 || wwan_hwsim_devsnum > 128)
508 return -EINVAL;
509
510 wwan_wq = alloc_workqueue("wwan_wq", 0, 0);
511 if (!wwan_wq)
512 return -ENOMEM;
513
514 wwan_hwsim_class = class_create("wwan_hwsim");
515 if (IS_ERR(wwan_hwsim_class)) {
516 err = PTR_ERR(wwan_hwsim_class);
517 goto err_wq_destroy;
518 }
519
520 wwan_hwsim_debugfs_topdir = debugfs_create_dir("wwan_hwsim", NULL);
521 wwan_hwsim_debugfs_devcreate =
522 debugfs_create_file("devcreate", 0200,
523 wwan_hwsim_debugfs_topdir, NULL,
524 &wwan_hwsim_debugfs_devcreate_fops);
525
526 err = wwan_hwsim_init_devs();
527 if (err)
528 goto err_clean_devs;
529
530 return 0;
531
532err_clean_devs:
533 debugfs_remove(wwan_hwsim_debugfs_devcreate); /* Avoid new devs */
534 wwan_hwsim_free_devs();
535 flush_workqueue(wwan_wq); /* Wait deletion works completion */
536 debugfs_remove(wwan_hwsim_debugfs_topdir);
537 class_destroy(wwan_hwsim_class);
538err_wq_destroy:
539 destroy_workqueue(wwan_wq);
540
541 return err;
542}
543
544static void __exit wwan_hwsim_exit(void)
545{
546 debugfs_remove(wwan_hwsim_debugfs_devcreate); /* Avoid new devs */
547 wwan_hwsim_free_devs();
548 flush_workqueue(wwan_wq); /* Wait deletion works completion */
549 debugfs_remove(wwan_hwsim_debugfs_topdir);
550 class_destroy(wwan_hwsim_class);
551 destroy_workqueue(wwan_wq);
552}
553
554module_init(wwan_hwsim_init);
555module_exit(wwan_hwsim_exit);
556
557MODULE_AUTHOR("Sergey Ryazanov");
558MODULE_DESCRIPTION("Device simulator for WWAN framework");
559MODULE_LICENSE("GPL");