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1/*
2 * Copyright (C) 2015, Marvell International Ltd.
3 *
4 * This software file (the "File") is distributed by Marvell International
5 * Ltd. under the terms of the GNU General Public License Version 2, June 1991
6 * (the "License"). You may use, redistribute and/or modify this File in
7 * accordance with the terms and conditions of the License, a copy of which
8 * is available on the worldwide web at
9 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt.
10 *
11 * THE FILE IS DISTRIBUTED AS-IS, WITHOUT WARRANTY OF ANY KIND, AND THE
12 * IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
13 * ARE EXPRESSLY DISCLAIMED. The License provides additional details about
14 * this warranty disclaimer.
15 */
16
17/* Inspired (hugely) by HCI LDISC implementation in Bluetooth.
18 *
19 * Copyright (C) 2000-2001 Qualcomm Incorporated
20 * Copyright (C) 2002-2003 Maxim Krasnyansky <maxk@qualcomm.com>
21 * Copyright (C) 2004-2005 Marcel Holtmann <marcel@holtmann.org>
22 */
23
24#include <linux/module.h>
25
26#include <linux/kernel.h>
27#include <linux/init.h>
28#include <linux/types.h>
29#include <linux/fcntl.h>
30#include <linux/interrupt.h>
31#include <linux/ptrace.h>
32#include <linux/poll.h>
33
34#include <linux/slab.h>
35#include <linux/tty.h>
36#include <linux/errno.h>
37#include <linux/string.h>
38#include <linux/signal.h>
39#include <linux/ioctl.h>
40#include <linux/skbuff.h>
41
42#include <net/nfc/nci.h>
43#include <net/nfc/nci_core.h>
44
45/* TX states */
46#define NCI_UART_SENDING 1
47#define NCI_UART_TX_WAKEUP 2
48
49static struct nci_uart *nci_uart_drivers[NCI_UART_DRIVER_MAX];
50
51static inline struct sk_buff *nci_uart_dequeue(struct nci_uart *nu)
52{
53 struct sk_buff *skb = nu->tx_skb;
54
55 if (!skb)
56 skb = skb_dequeue(&nu->tx_q);
57 else
58 nu->tx_skb = NULL;
59
60 return skb;
61}
62
63static inline int nci_uart_queue_empty(struct nci_uart *nu)
64{
65 if (nu->tx_skb)
66 return 0;
67
68 return skb_queue_empty(&nu->tx_q);
69}
70
71static int nci_uart_tx_wakeup(struct nci_uart *nu)
72{
73 if (test_and_set_bit(NCI_UART_SENDING, &nu->tx_state)) {
74 set_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
75 return 0;
76 }
77
78 schedule_work(&nu->write_work);
79
80 return 0;
81}
82
83static void nci_uart_write_work(struct work_struct *work)
84{
85 struct nci_uart *nu = container_of(work, struct nci_uart, write_work);
86 struct tty_struct *tty = nu->tty;
87 struct sk_buff *skb;
88
89restart:
90 clear_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
91
92 if (nu->ops.tx_start)
93 nu->ops.tx_start(nu);
94
95 while ((skb = nci_uart_dequeue(nu))) {
96 int len;
97
98 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
99 len = tty->ops->write(tty, skb->data, skb->len);
100 skb_pull(skb, len);
101 if (skb->len) {
102 nu->tx_skb = skb;
103 break;
104 }
105 kfree_skb(skb);
106 }
107
108 if (test_bit(NCI_UART_TX_WAKEUP, &nu->tx_state))
109 goto restart;
110
111 if (nu->ops.tx_done && nci_uart_queue_empty(nu))
112 nu->ops.tx_done(nu);
113
114 clear_bit(NCI_UART_SENDING, &nu->tx_state);
115}
116
117static int nci_uart_set_driver(struct tty_struct *tty, unsigned int driver)
118{
119 struct nci_uart *nu = NULL;
120 int ret;
121
122 if (driver >= NCI_UART_DRIVER_MAX)
123 return -EINVAL;
124
125 if (!nci_uart_drivers[driver])
126 return -ENOENT;
127
128 nu = kzalloc(sizeof(*nu), GFP_KERNEL);
129 if (!nu)
130 return -ENOMEM;
131
132 memcpy(nu, nci_uart_drivers[driver], sizeof(struct nci_uart));
133 nu->tty = tty;
134 tty->disc_data = nu;
135 skb_queue_head_init(&nu->tx_q);
136 INIT_WORK(&nu->write_work, nci_uart_write_work);
137 spin_lock_init(&nu->rx_lock);
138
139 ret = nu->ops.open(nu);
140 if (ret) {
141 tty->disc_data = NULL;
142 kfree(nu);
143 } else if (!try_module_get(nu->owner)) {
144 nu->ops.close(nu);
145 tty->disc_data = NULL;
146 kfree(nu);
147 return -ENOENT;
148 }
149 return ret;
150}
151
152/* ------ LDISC part ------ */
153
154/* nci_uart_tty_open
155 *
156 * Called when line discipline changed to NCI_UART.
157 *
158 * Arguments:
159 * tty pointer to tty info structure
160 * Return Value:
161 * 0 if success, otherwise error code
162 */
163static int nci_uart_tty_open(struct tty_struct *tty)
164{
165 /* Error if the tty has no write op instead of leaving an exploitable
166 * hole
167 */
168 if (!tty->ops->write)
169 return -EOPNOTSUPP;
170
171 tty->disc_data = NULL;
172 tty->receive_room = 65536;
173
174 /* Flush any pending characters in the driver */
175 tty_driver_flush_buffer(tty);
176
177 return 0;
178}
179
180/* nci_uart_tty_close()
181 *
182 * Called when the line discipline is changed to something
183 * else, the tty is closed, or the tty detects a hangup.
184 */
185static void nci_uart_tty_close(struct tty_struct *tty)
186{
187 struct nci_uart *nu = (void *)tty->disc_data;
188
189 /* Detach from the tty */
190 tty->disc_data = NULL;
191
192 if (!nu)
193 return;
194
195 if (nu->tx_skb)
196 kfree_skb(nu->tx_skb);
197 if (nu->rx_skb)
198 kfree_skb(nu->rx_skb);
199
200 skb_queue_purge(&nu->tx_q);
201
202 nu->ops.close(nu);
203 nu->tty = NULL;
204 module_put(nu->owner);
205
206 cancel_work_sync(&nu->write_work);
207
208 kfree(nu);
209}
210
211/* nci_uart_tty_wakeup()
212 *
213 * Callback for transmit wakeup. Called when low level
214 * device driver can accept more send data.
215 *
216 * Arguments: tty pointer to associated tty instance data
217 * Return Value: None
218 */
219static void nci_uart_tty_wakeup(struct tty_struct *tty)
220{
221 struct nci_uart *nu = (void *)tty->disc_data;
222
223 if (!nu)
224 return;
225
226 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
227
228 if (tty != nu->tty)
229 return;
230
231 nci_uart_tx_wakeup(nu);
232}
233
234/* nci_uart_tty_receive()
235 *
236 * Called by tty low level driver when receive data is
237 * available.
238 *
239 * Arguments: tty pointer to tty isntance data
240 * data pointer to received data
241 * flags pointer to flags for data
242 * count count of received data in bytes
243 *
244 * Return Value: None
245 */
246static void nci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
247 char *flags, int count)
248{
249 struct nci_uart *nu = (void *)tty->disc_data;
250
251 if (!nu || tty != nu->tty)
252 return;
253
254 spin_lock(&nu->rx_lock);
255 nu->ops.recv_buf(nu, (void *)data, flags, count);
256 spin_unlock(&nu->rx_lock);
257
258 tty_unthrottle(tty);
259}
260
261/* nci_uart_tty_ioctl()
262 *
263 * Process IOCTL system call for the tty device.
264 *
265 * Arguments:
266 *
267 * tty pointer to tty instance data
268 * file pointer to open file object for device
269 * cmd IOCTL command code
270 * arg argument for IOCTL call (cmd dependent)
271 *
272 * Return Value: Command dependent
273 */
274static int nci_uart_tty_ioctl(struct tty_struct *tty, struct file *file,
275 unsigned int cmd, unsigned long arg)
276{
277 struct nci_uart *nu = (void *)tty->disc_data;
278 int err = 0;
279
280 switch (cmd) {
281 case NCIUARTSETDRIVER:
282 if (!nu)
283 return nci_uart_set_driver(tty, (unsigned int)arg);
284 else
285 return -EBUSY;
286 break;
287 default:
288 err = n_tty_ioctl_helper(tty, file, cmd, arg);
289 break;
290 }
291
292 return err;
293}
294
295/* We don't provide read/write/poll interface for user space. */
296static ssize_t nci_uart_tty_read(struct tty_struct *tty, struct file *file,
297 unsigned char __user *buf, size_t nr)
298{
299 return 0;
300}
301
302static ssize_t nci_uart_tty_write(struct tty_struct *tty, struct file *file,
303 const unsigned char *data, size_t count)
304{
305 return 0;
306}
307
308static __poll_t nci_uart_tty_poll(struct tty_struct *tty,
309 struct file *filp, poll_table *wait)
310{
311 return 0;
312}
313
314static int nci_uart_send(struct nci_uart *nu, struct sk_buff *skb)
315{
316 /* Queue TX packet */
317 skb_queue_tail(&nu->tx_q, skb);
318
319 /* Try to start TX (if possible) */
320 nci_uart_tx_wakeup(nu);
321
322 return 0;
323}
324
325/* -- Default recv_buf handler --
326 *
327 * This handler supposes that NCI frames are sent over UART link without any
328 * framing. It reads NCI header, retrieve the packet size and once all packet
329 * bytes are received it passes it to nci_uart driver for processing.
330 */
331static int nci_uart_default_recv_buf(struct nci_uart *nu, const u8 *data,
332 char *flags, int count)
333{
334 int chunk_len;
335
336 if (!nu->ndev) {
337 nfc_err(nu->tty->dev,
338 "receive data from tty but no NCI dev is attached yet, drop buffer\n");
339 return 0;
340 }
341
342 /* Decode all incoming data in packets
343 * and enqueue then for processing.
344 */
345 while (count > 0) {
346 /* If this is the first data of a packet, allocate a buffer */
347 if (!nu->rx_skb) {
348 nu->rx_packet_len = -1;
349 nu->rx_skb = nci_skb_alloc(nu->ndev,
350 NCI_MAX_PACKET_SIZE,
351 GFP_KERNEL);
352 if (!nu->rx_skb)
353 return -ENOMEM;
354 }
355
356 /* Eat byte after byte till full packet header is received */
357 if (nu->rx_skb->len < NCI_CTRL_HDR_SIZE) {
358 skb_put_u8(nu->rx_skb, *data++);
359 --count;
360 continue;
361 }
362
363 /* Header was received but packet len was not read */
364 if (nu->rx_packet_len < 0)
365 nu->rx_packet_len = NCI_CTRL_HDR_SIZE +
366 nci_plen(nu->rx_skb->data);
367
368 /* Compute how many bytes are missing and how many bytes can
369 * be consumed.
370 */
371 chunk_len = nu->rx_packet_len - nu->rx_skb->len;
372 if (count < chunk_len)
373 chunk_len = count;
374 skb_put_data(nu->rx_skb, data, chunk_len);
375 data += chunk_len;
376 count -= chunk_len;
377
378 /* Chcek if packet is fully received */
379 if (nu->rx_packet_len == nu->rx_skb->len) {
380 /* Pass RX packet to driver */
381 if (nu->ops.recv(nu, nu->rx_skb) != 0)
382 nfc_err(nu->tty->dev, "corrupted RX packet\n");
383 /* Next packet will be a new one */
384 nu->rx_skb = NULL;
385 }
386 }
387
388 return 0;
389}
390
391/* -- Default recv handler -- */
392static int nci_uart_default_recv(struct nci_uart *nu, struct sk_buff *skb)
393{
394 return nci_recv_frame(nu->ndev, skb);
395}
396
397int nci_uart_register(struct nci_uart *nu)
398{
399 if (!nu || !nu->ops.open ||
400 !nu->ops.recv || !nu->ops.close)
401 return -EINVAL;
402
403 /* Set the send callback */
404 nu->ops.send = nci_uart_send;
405
406 /* Install default handlers if not overridden */
407 if (!nu->ops.recv_buf)
408 nu->ops.recv_buf = nci_uart_default_recv_buf;
409 if (!nu->ops.recv)
410 nu->ops.recv = nci_uart_default_recv;
411
412 /* Add this driver in the driver list */
413 if (nci_uart_drivers[nu->driver]) {
414 pr_err("driver %d is already registered\n", nu->driver);
415 return -EBUSY;
416 }
417 nci_uart_drivers[nu->driver] = nu;
418
419 pr_info("NCI uart driver '%s [%d]' registered\n", nu->name, nu->driver);
420
421 return 0;
422}
423EXPORT_SYMBOL_GPL(nci_uart_register);
424
425void nci_uart_unregister(struct nci_uart *nu)
426{
427 pr_info("NCI uart driver '%s [%d]' unregistered\n", nu->name,
428 nu->driver);
429
430 /* Remove this driver from the driver list */
431 nci_uart_drivers[nu->driver] = NULL;
432}
433EXPORT_SYMBOL_GPL(nci_uart_unregister);
434
435void nci_uart_set_config(struct nci_uart *nu, int baudrate, int flow_ctrl)
436{
437 struct ktermios new_termios;
438
439 if (!nu->tty)
440 return;
441
442 down_read(&nu->tty->termios_rwsem);
443 new_termios = nu->tty->termios;
444 up_read(&nu->tty->termios_rwsem);
445 tty_termios_encode_baud_rate(&new_termios, baudrate, baudrate);
446
447 if (flow_ctrl)
448 new_termios.c_cflag |= CRTSCTS;
449 else
450 new_termios.c_cflag &= ~CRTSCTS;
451
452 tty_set_termios(nu->tty, &new_termios);
453}
454EXPORT_SYMBOL_GPL(nci_uart_set_config);
455
456static struct tty_ldisc_ops nci_uart_ldisc = {
457 .magic = TTY_LDISC_MAGIC,
458 .owner = THIS_MODULE,
459 .name = "n_nci",
460 .open = nci_uart_tty_open,
461 .close = nci_uart_tty_close,
462 .read = nci_uart_tty_read,
463 .write = nci_uart_tty_write,
464 .poll = nci_uart_tty_poll,
465 .receive_buf = nci_uart_tty_receive,
466 .write_wakeup = nci_uart_tty_wakeup,
467 .ioctl = nci_uart_tty_ioctl,
468};
469
470static int __init nci_uart_init(void)
471{
472 memset(nci_uart_drivers, 0, sizeof(nci_uart_drivers));
473 return tty_register_ldisc(N_NCI, &nci_uart_ldisc);
474}
475
476static void __exit nci_uart_exit(void)
477{
478 tty_unregister_ldisc(N_NCI);
479}
480
481module_init(nci_uart_init);
482module_exit(nci_uart_exit);
483
484MODULE_AUTHOR("Marvell International Ltd.");
485MODULE_DESCRIPTION("NFC NCI UART driver");
486MODULE_LICENSE("GPL");
487MODULE_ALIAS_LDISC(N_NCI);