1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * xhci-dbgtty.c - tty glue for xHCI debug capability
4 *
5 * Copyright (C) 2017 Intel Corporation
6 *
7 * Author: Lu Baolu <baolu.lu@linux.intel.com>
8 */
9
10 #include <linux/slab.h>
11 #include <linux/tty.h>
12 #include <linux/tty_flip.h>
13
14 #include "xhci.h"
15 #include "xhci-dbgcap.h"
16
17 static int dbc_tty_init(void);
18 static void dbc_tty_exit(void);
19
20 static struct tty_driver *dbc_tty_driver;
21
dbc_to_port(struct xhci_dbc * dbc)22 static inline struct dbc_port *dbc_to_port(struct xhci_dbc *dbc)
23 {
24 return dbc->priv;
25 }
26
27 static unsigned int
dbc_send_packet(struct dbc_port * port,char * packet,unsigned int size)28 dbc_send_packet(struct dbc_port *port, char *packet, unsigned int size)
29 {
30 unsigned int len;
31
32 len = kfifo_len(&port->write_fifo);
33 if (len < size)
34 size = len;
35 if (size != 0)
36 size = kfifo_out(&port->write_fifo, packet, size);
37 return size;
38 }
39
dbc_start_tx(struct dbc_port * port)40 static int dbc_start_tx(struct dbc_port *port)
41 __releases(&port->port_lock)
42 __acquires(&port->port_lock)
43 {
44 int len;
45 struct dbc_request *req;
46 int status = 0;
47 bool do_tty_wake = false;
48 struct list_head *pool = &port->write_pool;
49
50 while (!list_empty(pool)) {
51 req = list_entry(pool->next, struct dbc_request, list_pool);
52 len = dbc_send_packet(port, req->buf, DBC_MAX_PACKET);
53 if (len == 0)
54 break;
55 do_tty_wake = true;
56
57 req->length = len;
58 list_del(&req->list_pool);
59
60 spin_unlock(&port->port_lock);
61 status = dbc_ep_queue(req);
62 spin_lock(&port->port_lock);
63
64 if (status) {
65 list_add(&req->list_pool, pool);
66 break;
67 }
68 }
69
70 if (do_tty_wake && port->port.tty)
71 tty_wakeup(port->port.tty);
72
73 return status;
74 }
75
dbc_start_rx(struct dbc_port * port)76 static void dbc_start_rx(struct dbc_port *port)
77 __releases(&port->port_lock)
78 __acquires(&port->port_lock)
79 {
80 struct dbc_request *req;
81 int status;
82 struct list_head *pool = &port->read_pool;
83
84 while (!list_empty(pool)) {
85 if (!port->port.tty)
86 break;
87
88 req = list_entry(pool->next, struct dbc_request, list_pool);
89 list_del(&req->list_pool);
90 req->length = DBC_MAX_PACKET;
91
92 spin_unlock(&port->port_lock);
93 status = dbc_ep_queue(req);
94 spin_lock(&port->port_lock);
95
96 if (status) {
97 list_add(&req->list_pool, pool);
98 break;
99 }
100 }
101 }
102
103 static void
dbc_read_complete(struct xhci_dbc * dbc,struct dbc_request * req)104 dbc_read_complete(struct xhci_dbc *dbc, struct dbc_request *req)
105 {
106 unsigned long flags;
107 struct dbc_port *port = dbc_to_port(dbc);
108
109 spin_lock_irqsave(&port->port_lock, flags);
110 list_add_tail(&req->list_pool, &port->read_queue);
111 tasklet_schedule(&port->push);
112 spin_unlock_irqrestore(&port->port_lock, flags);
113 }
114
dbc_write_complete(struct xhci_dbc * dbc,struct dbc_request * req)115 static void dbc_write_complete(struct xhci_dbc *dbc, struct dbc_request *req)
116 {
117 unsigned long flags;
118 struct dbc_port *port = dbc_to_port(dbc);
119
120 spin_lock_irqsave(&port->port_lock, flags);
121 list_add(&req->list_pool, &port->write_pool);
122 switch (req->status) {
123 case 0:
124 dbc_start_tx(port);
125 break;
126 case -ESHUTDOWN:
127 break;
128 default:
129 dev_warn(dbc->dev, "unexpected write complete status %d\n",
130 req->status);
131 break;
132 }
133 spin_unlock_irqrestore(&port->port_lock, flags);
134 }
135
xhci_dbc_free_req(struct dbc_request * req)136 static void xhci_dbc_free_req(struct dbc_request *req)
137 {
138 kfree(req->buf);
139 dbc_free_request(req);
140 }
141
142 static int
xhci_dbc_alloc_requests(struct xhci_dbc * dbc,unsigned int direction,struct list_head * head,void (* fn)(struct xhci_dbc *,struct dbc_request *))143 xhci_dbc_alloc_requests(struct xhci_dbc *dbc, unsigned int direction,
144 struct list_head *head,
145 void (*fn)(struct xhci_dbc *, struct dbc_request *))
146 {
147 int i;
148 struct dbc_request *req;
149
150 for (i = 0; i < DBC_QUEUE_SIZE; i++) {
151 req = dbc_alloc_request(dbc, direction, GFP_KERNEL);
152 if (!req)
153 break;
154
155 req->length = DBC_MAX_PACKET;
156 req->buf = kmalloc(req->length, GFP_KERNEL);
157 if (!req->buf) {
158 dbc_free_request(req);
159 break;
160 }
161
162 req->complete = fn;
163 list_add_tail(&req->list_pool, head);
164 }
165
166 return list_empty(head) ? -ENOMEM : 0;
167 }
168
169 static void
xhci_dbc_free_requests(struct list_head * head)170 xhci_dbc_free_requests(struct list_head *head)
171 {
172 struct dbc_request *req;
173
174 while (!list_empty(head)) {
175 req = list_entry(head->next, struct dbc_request, list_pool);
176 list_del(&req->list_pool);
177 xhci_dbc_free_req(req);
178 }
179 }
180
dbc_tty_install(struct tty_driver * driver,struct tty_struct * tty)181 static int dbc_tty_install(struct tty_driver *driver, struct tty_struct *tty)
182 {
183 struct dbc_port *port = driver->driver_state;
184
185 tty->driver_data = port;
186
187 return tty_port_install(&port->port, driver, tty);
188 }
189
dbc_tty_open(struct tty_struct * tty,struct file * file)190 static int dbc_tty_open(struct tty_struct *tty, struct file *file)
191 {
192 struct dbc_port *port = tty->driver_data;
193
194 return tty_port_open(&port->port, tty, file);
195 }
196
dbc_tty_close(struct tty_struct * tty,struct file * file)197 static void dbc_tty_close(struct tty_struct *tty, struct file *file)
198 {
199 struct dbc_port *port = tty->driver_data;
200
201 tty_port_close(&port->port, tty, file);
202 }
203
dbc_tty_write(struct tty_struct * tty,const unsigned char * buf,int count)204 static int dbc_tty_write(struct tty_struct *tty,
205 const unsigned char *buf,
206 int count)
207 {
208 struct dbc_port *port = tty->driver_data;
209 unsigned long flags;
210
211 spin_lock_irqsave(&port->port_lock, flags);
212 if (count)
213 count = kfifo_in(&port->write_fifo, buf, count);
214 dbc_start_tx(port);
215 spin_unlock_irqrestore(&port->port_lock, flags);
216
217 return count;
218 }
219
dbc_tty_put_char(struct tty_struct * tty,unsigned char ch)220 static int dbc_tty_put_char(struct tty_struct *tty, unsigned char ch)
221 {
222 struct dbc_port *port = tty->driver_data;
223 unsigned long flags;
224 int status;
225
226 spin_lock_irqsave(&port->port_lock, flags);
227 status = kfifo_put(&port->write_fifo, ch);
228 spin_unlock_irqrestore(&port->port_lock, flags);
229
230 return status;
231 }
232
dbc_tty_flush_chars(struct tty_struct * tty)233 static void dbc_tty_flush_chars(struct tty_struct *tty)
234 {
235 struct dbc_port *port = tty->driver_data;
236 unsigned long flags;
237
238 spin_lock_irqsave(&port->port_lock, flags);
239 dbc_start_tx(port);
240 spin_unlock_irqrestore(&port->port_lock, flags);
241 }
242
dbc_tty_write_room(struct tty_struct * tty)243 static unsigned int dbc_tty_write_room(struct tty_struct *tty)
244 {
245 struct dbc_port *port = tty->driver_data;
246 unsigned long flags;
247 unsigned int room;
248
249 spin_lock_irqsave(&port->port_lock, flags);
250 room = kfifo_avail(&port->write_fifo);
251 spin_unlock_irqrestore(&port->port_lock, flags);
252
253 return room;
254 }
255
dbc_tty_chars_in_buffer(struct tty_struct * tty)256 static unsigned int dbc_tty_chars_in_buffer(struct tty_struct *tty)
257 {
258 struct dbc_port *port = tty->driver_data;
259 unsigned long flags;
260 unsigned int chars;
261
262 spin_lock_irqsave(&port->port_lock, flags);
263 chars = kfifo_len(&port->write_fifo);
264 spin_unlock_irqrestore(&port->port_lock, flags);
265
266 return chars;
267 }
268
dbc_tty_unthrottle(struct tty_struct * tty)269 static void dbc_tty_unthrottle(struct tty_struct *tty)
270 {
271 struct dbc_port *port = tty->driver_data;
272 unsigned long flags;
273
274 spin_lock_irqsave(&port->port_lock, flags);
275 tasklet_schedule(&port->push);
276 spin_unlock_irqrestore(&port->port_lock, flags);
277 }
278
279 static const struct tty_operations dbc_tty_ops = {
280 .install = dbc_tty_install,
281 .open = dbc_tty_open,
282 .close = dbc_tty_close,
283 .write = dbc_tty_write,
284 .put_char = dbc_tty_put_char,
285 .flush_chars = dbc_tty_flush_chars,
286 .write_room = dbc_tty_write_room,
287 .chars_in_buffer = dbc_tty_chars_in_buffer,
288 .unthrottle = dbc_tty_unthrottle,
289 };
290
dbc_rx_push(struct tasklet_struct * t)291 static void dbc_rx_push(struct tasklet_struct *t)
292 {
293 struct dbc_request *req;
294 struct tty_struct *tty;
295 unsigned long flags;
296 bool do_push = false;
297 bool disconnect = false;
298 struct dbc_port *port = from_tasklet(port, t, push);
299 struct list_head *queue = &port->read_queue;
300
301 spin_lock_irqsave(&port->port_lock, flags);
302 tty = port->port.tty;
303 while (!list_empty(queue)) {
304 req = list_first_entry(queue, struct dbc_request, list_pool);
305
306 if (tty && tty_throttled(tty))
307 break;
308
309 switch (req->status) {
310 case 0:
311 break;
312 case -ESHUTDOWN:
313 disconnect = true;
314 break;
315 default:
316 pr_warn("ttyDBC0: unexpected RX status %d\n",
317 req->status);
318 break;
319 }
320
321 if (req->actual) {
322 char *packet = req->buf;
323 unsigned int n, size = req->actual;
324 int count;
325
326 n = port->n_read;
327 if (n) {
328 packet += n;
329 size -= n;
330 }
331
332 count = tty_insert_flip_string(&port->port, packet,
333 size);
334 if (count)
335 do_push = true;
336 if (count != size) {
337 port->n_read += count;
338 break;
339 }
340 port->n_read = 0;
341 }
342
343 list_move(&req->list_pool, &port->read_pool);
344 }
345
346 if (do_push)
347 tty_flip_buffer_push(&port->port);
348
349 if (!list_empty(queue) && tty) {
350 if (!tty_throttled(tty)) {
351 if (do_push)
352 tasklet_schedule(&port->push);
353 else
354 pr_warn("ttyDBC0: RX not scheduled?\n");
355 }
356 }
357
358 if (!disconnect)
359 dbc_start_rx(port);
360
361 spin_unlock_irqrestore(&port->port_lock, flags);
362 }
363
dbc_port_activate(struct tty_port * _port,struct tty_struct * tty)364 static int dbc_port_activate(struct tty_port *_port, struct tty_struct *tty)
365 {
366 unsigned long flags;
367 struct dbc_port *port = container_of(_port, struct dbc_port, port);
368
369 spin_lock_irqsave(&port->port_lock, flags);
370 dbc_start_rx(port);
371 spin_unlock_irqrestore(&port->port_lock, flags);
372
373 return 0;
374 }
375
376 static const struct tty_port_operations dbc_port_ops = {
377 .activate = dbc_port_activate,
378 };
379
380 static void
xhci_dbc_tty_init_port(struct xhci_dbc * dbc,struct dbc_port * port)381 xhci_dbc_tty_init_port(struct xhci_dbc *dbc, struct dbc_port *port)
382 {
383 tty_port_init(&port->port);
384 spin_lock_init(&port->port_lock);
385 tasklet_setup(&port->push, dbc_rx_push);
386 INIT_LIST_HEAD(&port->read_pool);
387 INIT_LIST_HEAD(&port->read_queue);
388 INIT_LIST_HEAD(&port->write_pool);
389
390 port->port.ops = &dbc_port_ops;
391 port->n_read = 0;
392 }
393
394 static void
xhci_dbc_tty_exit_port(struct dbc_port * port)395 xhci_dbc_tty_exit_port(struct dbc_port *port)
396 {
397 tasklet_kill(&port->push);
398 tty_port_destroy(&port->port);
399 }
400
xhci_dbc_tty_register_device(struct xhci_dbc * dbc)401 static int xhci_dbc_tty_register_device(struct xhci_dbc *dbc)
402 {
403 int ret;
404 struct device *tty_dev;
405 struct dbc_port *port = dbc_to_port(dbc);
406
407 if (port->registered)
408 return -EBUSY;
409
410 xhci_dbc_tty_init_port(dbc, port);
411
412 ret = kfifo_alloc(&port->write_fifo, DBC_WRITE_BUF_SIZE, GFP_KERNEL);
413 if (ret)
414 goto err_exit_port;
415
416 ret = xhci_dbc_alloc_requests(dbc, BULK_IN, &port->read_pool,
417 dbc_read_complete);
418 if (ret)
419 goto err_free_fifo;
420
421 ret = xhci_dbc_alloc_requests(dbc, BULK_OUT, &port->write_pool,
422 dbc_write_complete);
423 if (ret)
424 goto err_free_requests;
425
426 tty_dev = tty_port_register_device(&port->port,
427 dbc_tty_driver, 0, NULL);
428 if (IS_ERR(tty_dev)) {
429 ret = PTR_ERR(tty_dev);
430 goto err_free_requests;
431 }
432
433 port->registered = true;
434
435 return 0;
436
437 err_free_requests:
438 xhci_dbc_free_requests(&port->read_pool);
439 xhci_dbc_free_requests(&port->write_pool);
440 err_free_fifo:
441 kfifo_free(&port->write_fifo);
442 err_exit_port:
443 xhci_dbc_tty_exit_port(port);
444
445 dev_err(dbc->dev, "can't register tty port, err %d\n", ret);
446
447 return ret;
448 }
449
xhci_dbc_tty_unregister_device(struct xhci_dbc * dbc)450 static void xhci_dbc_tty_unregister_device(struct xhci_dbc *dbc)
451 {
452 struct dbc_port *port = dbc_to_port(dbc);
453
454 if (!port->registered)
455 return;
456 tty_unregister_device(dbc_tty_driver, 0);
457 xhci_dbc_tty_exit_port(port);
458 port->registered = false;
459
460 kfifo_free(&port->write_fifo);
461 xhci_dbc_free_requests(&port->read_pool);
462 xhci_dbc_free_requests(&port->read_queue);
463 xhci_dbc_free_requests(&port->write_pool);
464 }
465
466 static const struct dbc_driver dbc_driver = {
467 .configure = xhci_dbc_tty_register_device,
468 .disconnect = xhci_dbc_tty_unregister_device,
469 };
470
xhci_dbc_tty_probe(struct device * dev,void __iomem * base,struct xhci_hcd * xhci)471 int xhci_dbc_tty_probe(struct device *dev, void __iomem *base, struct xhci_hcd *xhci)
472 {
473 struct xhci_dbc *dbc;
474 struct dbc_port *port;
475 int status;
476
477 /* dbc_tty_init will be called by module init() in the future */
478 status = dbc_tty_init();
479 if (status)
480 return status;
481
482 port = kzalloc(sizeof(*port), GFP_KERNEL);
483 if (!port) {
484 status = -ENOMEM;
485 goto out;
486 }
487
488 dbc_tty_driver->driver_state = port;
489
490 dbc = xhci_alloc_dbc(dev, base, &dbc_driver);
491 if (!dbc) {
492 status = -ENOMEM;
493 goto out2;
494 }
495
496 dbc->priv = port;
497
498 /* get rid of xhci once this is a real driver binding to a device */
499 xhci->dbc = dbc;
500
501 return 0;
502 out2:
503 kfree(port);
504 out:
505 /* dbc_tty_exit will be called by module_exit() in the future */
506 dbc_tty_exit();
507 return status;
508 }
509
510 /*
511 * undo what probe did, assume dbc is stopped already.
512 * we also assume tty_unregister_device() is called before this
513 */
xhci_dbc_tty_remove(struct xhci_dbc * dbc)514 void xhci_dbc_tty_remove(struct xhci_dbc *dbc)
515 {
516 struct dbc_port *port = dbc_to_port(dbc);
517
518 xhci_dbc_remove(dbc);
519 kfree(port);
520
521 /* dbc_tty_exit will be called by module_exit() in the future */
522 dbc_tty_exit();
523 }
524
dbc_tty_init(void)525 static int dbc_tty_init(void)
526 {
527 int ret;
528
529 dbc_tty_driver = tty_alloc_driver(1, TTY_DRIVER_REAL_RAW |
530 TTY_DRIVER_DYNAMIC_DEV);
531 if (IS_ERR(dbc_tty_driver))
532 return PTR_ERR(dbc_tty_driver);
533
534 dbc_tty_driver->driver_name = "dbc_serial";
535 dbc_tty_driver->name = "ttyDBC";
536
537 dbc_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
538 dbc_tty_driver->subtype = SERIAL_TYPE_NORMAL;
539 dbc_tty_driver->init_termios = tty_std_termios;
540 dbc_tty_driver->init_termios.c_cflag =
541 B9600 | CS8 | CREAD | HUPCL | CLOCAL;
542 dbc_tty_driver->init_termios.c_ispeed = 9600;
543 dbc_tty_driver->init_termios.c_ospeed = 9600;
544
545 tty_set_operations(dbc_tty_driver, &dbc_tty_ops);
546
547 ret = tty_register_driver(dbc_tty_driver);
548 if (ret) {
549 pr_err("Can't register dbc tty driver\n");
550 tty_driver_kref_put(dbc_tty_driver);
551 }
552 return ret;
553 }
554
dbc_tty_exit(void)555 static void dbc_tty_exit(void)
556 {
557 if (dbc_tty_driver) {
558 tty_unregister_driver(dbc_tty_driver);
559 tty_driver_kref_put(dbc_tty_driver);
560 dbc_tty_driver = NULL;
561 }
562 }
563