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WIP FPC-III support
[linux/fpc-iii.git] / drivers / net / caif / caif_serial.c
blobbcc14c5875bf0958109d239a9eb7c72700747670
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) ST-Ericsson AB 2010
4 * Author: Sjur Brendeland
5 */
6
7 #include <linux/hardirq.h>
8 #include <linux/init.h>
9 #include <linux/module.h>
10 #include <linux/device.h>
11 #include <linux/types.h>
12 #include <linux/skbuff.h>
13 #include <linux/netdevice.h>
14 #include <linux/rtnetlink.h>
15 #include <linux/tty.h>
16 #include <linux/file.h>
17 #include <linux/if_arp.h>
18 #include <net/caif/caif_device.h>
19 #include <net/caif/cfcnfg.h>
20 #include <linux/err.h>
21 #include <linux/debugfs.h>
22
23 MODULE_LICENSE("GPL");
24 MODULE_AUTHOR("Sjur Brendeland");
25 MODULE_DESCRIPTION("CAIF serial device TTY line discipline");
26 MODULE_LICENSE("GPL");
27 MODULE_ALIAS_LDISC(N_CAIF);
28
29 #define SEND_QUEUE_LOW 10
30 #define SEND_QUEUE_HIGH 100
31 #define CAIF_SENDING 1 /* Bit 1 = 0x02*/
32 #define CAIF_FLOW_OFF_SENT 4 /* Bit 4 = 0x10 */
33 #define MAX_WRITE_CHUNK 4096
34 #define ON 1
35 #define OFF 0
36 #define CAIF_MAX_MTU 4096
37
38 static DEFINE_SPINLOCK(ser_lock);
39 static LIST_HEAD(ser_list);
40 static LIST_HEAD(ser_release_list);
41
42 static bool ser_loop;
43 module_param(ser_loop, bool, 0444);
44 MODULE_PARM_DESC(ser_loop, "Run in simulated loopback mode.");
45
46 static bool ser_use_stx = true;
47 module_param(ser_use_stx, bool, 0444);
48 MODULE_PARM_DESC(ser_use_stx, "STX enabled or not.");
49
50 static bool ser_use_fcs = true;
51
52 module_param(ser_use_fcs, bool, 0444);
53 MODULE_PARM_DESC(ser_use_fcs, "FCS enabled or not.");
54
55 static int ser_write_chunk = MAX_WRITE_CHUNK;
56 module_param(ser_write_chunk, int, 0444);
57
58 MODULE_PARM_DESC(ser_write_chunk, "Maximum size of data written to UART.");
59
60 static struct dentry *debugfsdir;
61
62 static int caif_net_open(struct net_device *dev);
63 static int caif_net_close(struct net_device *dev);
64
65 struct ser_device {
66 struct caif_dev_common common;
67 struct list_head node;
68 struct net_device *dev;
69 struct sk_buff_head head;
70 struct tty_struct *tty;
71 bool tx_started;
72 unsigned long state;
73 #ifdef CONFIG_DEBUG_FS
74 struct dentry *debugfs_tty_dir;
75 struct debugfs_blob_wrapper tx_blob;
76 struct debugfs_blob_wrapper rx_blob;
77 u8 rx_data[128];
78 u8 tx_data[128];
79 u8 tty_status;
80
81 #endif
82 };
83
84 static void caifdev_setup(struct net_device *dev);
85 static void ldisc_tx_wakeup(struct tty_struct *tty);
86 #ifdef CONFIG_DEBUG_FS
87 static inline void update_tty_status(struct ser_device *ser)
88 {
89 ser->tty_status =
90 ser->tty->stopped << 5 |
91 ser->tty->flow_stopped << 3 |
92 ser->tty->packet << 2 |
93 ser->tty->port->low_latency << 1;
94 }
95 static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty)
96 {
97 ser->debugfs_tty_dir = debugfs_create_dir(tty->name, debugfsdir);
98
99 debugfs_create_blob("last_tx_msg", 0400, ser->debugfs_tty_dir,
100 &ser->tx_blob);
101
102 debugfs_create_blob("last_rx_msg", 0400, ser->debugfs_tty_dir,
103 &ser->rx_blob);
104
105 debugfs_create_xul("ser_state", 0400, ser->debugfs_tty_dir,
106 &ser->state);
107
108 debugfs_create_x8("tty_status", 0400, ser->debugfs_tty_dir,
109 &ser->tty_status);
110
111 ser->tx_blob.data = ser->tx_data;
112 ser->tx_blob.size = 0;
113 ser->rx_blob.data = ser->rx_data;
114 ser->rx_blob.size = 0;
115 }
116
117 static inline void debugfs_deinit(struct ser_device *ser)
118 {
119 debugfs_remove_recursive(ser->debugfs_tty_dir);
120 }
121
122 static inline void debugfs_rx(struct ser_device *ser, const u8 *data, int size)
123 {
124 if (size > sizeof(ser->rx_data))
125 size = sizeof(ser->rx_data);
126 memcpy(ser->rx_data, data, size);
127 ser->rx_blob.data = ser->rx_data;
128 ser->rx_blob.size = size;
129 }
130
131 static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size)
132 {
133 if (size > sizeof(ser->tx_data))
134 size = sizeof(ser->tx_data);
135 memcpy(ser->tx_data, data, size);
136 ser->tx_blob.data = ser->tx_data;
137 ser->tx_blob.size = size;
138 }
139 #else
140 static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty)
141 {
142 }
143
144 static inline void debugfs_deinit(struct ser_device *ser)
145 {
146 }
147
148 static inline void update_tty_status(struct ser_device *ser)
149 {
150 }
151
152 static inline void debugfs_rx(struct ser_device *ser, const u8 *data, int size)
153 {
154 }
155
156 static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size)
157 {
158 }
159
160 #endif
161
162 static void ldisc_receive(struct tty_struct *tty, const u8 *data,
163 char *flags, int count)
164 {
165 struct sk_buff *skb = NULL;
166 struct ser_device *ser;
167 int ret;
168
169 ser = tty->disc_data;
170
171 /*
172 * NOTE: flags may contain information about break or overrun.
173 * This is not yet handled.
174 */
175
176
177 /*
178 * Workaround for garbage at start of transmission,
179 * only enable if STX handling is not enabled.
180 */
181 if (!ser->common.use_stx && !ser->tx_started) {
182 dev_info(&ser->dev->dev,
183 "Bytes received before initial transmission -"
184 "bytes discarded.\n");
185 return;
186 }
187
188 BUG_ON(ser->dev == NULL);
189
190 /* Get a suitable caif packet and copy in data. */
191 skb = netdev_alloc_skb(ser->dev, count+1);
192 if (skb == NULL)
193 return;
194 skb_put_data(skb, data, count);
195
196 skb->protocol = htons(ETH_P_CAIF);
197 skb_reset_mac_header(skb);
198 debugfs_rx(ser, data, count);
199 /* Push received packet up the stack. */
200 ret = netif_rx_ni(skb);
201 if (!ret) {
202 ser->dev->stats.rx_packets++;
203 ser->dev->stats.rx_bytes += count;
204 } else
205 ++ser->dev->stats.rx_dropped;
206 update_tty_status(ser);
207 }
208
209 static int handle_tx(struct ser_device *ser)
210 {
211 struct tty_struct *tty;
212 struct sk_buff *skb;
213 int tty_wr, len, room;
214
215 tty = ser->tty;
216 ser->tx_started = true;
217
218 /* Enter critical section */
219 if (test_and_set_bit(CAIF_SENDING, &ser->state))
220 return 0;
221
222 /* skb_peek is safe because handle_tx is called after skb_queue_tail */
223 while ((skb = skb_peek(&ser->head)) != NULL) {
224
225 /* Make sure you don't write too much */
226 len = skb->len;
227 room = tty_write_room(tty);
228 if (!room)
229 break;
230 if (room > ser_write_chunk)
231 room = ser_write_chunk;
232 if (len > room)
233 len = room;
234
235 /* Write to tty or loopback */
236 if (!ser_loop) {
237 tty_wr = tty->ops->write(tty, skb->data, len);
238 update_tty_status(ser);
239 } else {
240 tty_wr = len;
241 ldisc_receive(tty, skb->data, NULL, len);
242 }
243 ser->dev->stats.tx_packets++;
244 ser->dev->stats.tx_bytes += tty_wr;
245
246 /* Error on TTY ?! */
247 if (tty_wr < 0)
248 goto error;
249 /* Reduce buffer written, and discard if empty */
250 skb_pull(skb, tty_wr);
251 if (skb->len == 0) {
252 struct sk_buff *tmp = skb_dequeue(&ser->head);
253 WARN_ON(tmp != skb);
254 dev_consume_skb_any(skb);
255 }
256 }
257 /* Send flow off if queue is empty */
258 if (ser->head.qlen <= SEND_QUEUE_LOW &&
259 test_and_clear_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
260 ser->common.flowctrl != NULL)
261 ser->common.flowctrl(ser->dev, ON);
262 clear_bit(CAIF_SENDING, &ser->state);
263 return 0;
264 error:
265 clear_bit(CAIF_SENDING, &ser->state);
266 return tty_wr;
267 }
268
269 static netdev_tx_t caif_xmit(struct sk_buff *skb, struct net_device *dev)
270 {
271 struct ser_device *ser;
272
273 if (WARN_ON(!dev))
274 return -EINVAL;
275
276 ser = netdev_priv(dev);
277
278 /* Send flow off once, on high water mark */
279 if (ser->head.qlen > SEND_QUEUE_HIGH &&
280 !test_and_set_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
281 ser->common.flowctrl != NULL)
282
283 ser->common.flowctrl(ser->dev, OFF);
284
285 skb_queue_tail(&ser->head, skb);
286 return handle_tx(ser);
287 }
288
289
290 static void ldisc_tx_wakeup(struct tty_struct *tty)
291 {
292 struct ser_device *ser;
293
294 ser = tty->disc_data;
295 BUG_ON(ser == NULL);
296 WARN_ON(ser->tty != tty);
297 handle_tx(ser);
298 }
299
300
301 static void ser_release(struct work_struct *work)
302 {
303 struct list_head list;
304 struct ser_device *ser, *tmp;
305
306 spin_lock(&ser_lock);
307 list_replace_init(&ser_release_list, &list);
308 spin_unlock(&ser_lock);
309
310 if (!list_empty(&list)) {
311 rtnl_lock();
312 list_for_each_entry_safe(ser, tmp, &list, node) {
313 dev_close(ser->dev);
314 unregister_netdevice(ser->dev);
315 debugfs_deinit(ser);
316 }
317 rtnl_unlock();
318 }
319 }
320
321 static DECLARE_WORK(ser_release_work, ser_release);
322
323 static int ldisc_open(struct tty_struct *tty)
324 {
325 struct ser_device *ser;
326 struct net_device *dev;
327 char name[64];
328 int result;
329
330 /* No write no play */
331 if (tty->ops->write == NULL)
332 return -EOPNOTSUPP;
333 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_TTY_CONFIG))
334 return -EPERM;
335
336 /* release devices to avoid name collision */
337 ser_release(NULL);
338
339 result = snprintf(name, sizeof(name), "cf%s", tty->name);
340 if (result >= IFNAMSIZ)
341 return -EINVAL;
342 dev = alloc_netdev(sizeof(*ser), name, NET_NAME_UNKNOWN,
343 caifdev_setup);
344 if (!dev)
345 return -ENOMEM;
346
347 ser = netdev_priv(dev);
348 ser->tty = tty_kref_get(tty);
349 ser->dev = dev;
350 debugfs_init(ser, tty);
351 tty->receive_room = N_TTY_BUF_SIZE;
352 tty->disc_data = ser;
353 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
354 rtnl_lock();
355 result = register_netdevice(dev);
356 if (result) {
357 rtnl_unlock();
358 free_netdev(dev);
359 return -ENODEV;
360 }
361
362 spin_lock(&ser_lock);
363 list_add(&ser->node, &ser_list);
364 spin_unlock(&ser_lock);
365 rtnl_unlock();
366 netif_stop_queue(dev);
367 update_tty_status(ser);
368 return 0;
369 }
370
371 static void ldisc_close(struct tty_struct *tty)
372 {
373 struct ser_device *ser = tty->disc_data;
374
375 tty_kref_put(ser->tty);
376
377 spin_lock(&ser_lock);
378 list_move(&ser->node, &ser_release_list);
379 spin_unlock(&ser_lock);
380 schedule_work(&ser_release_work);
381 }
382
383 /* The line discipline structure. */
384 static struct tty_ldisc_ops caif_ldisc = {
385 .owner = THIS_MODULE,
386 .magic = TTY_LDISC_MAGIC,
387 .name = "n_caif",
388 .open = ldisc_open,
389 .close = ldisc_close,
390 .receive_buf = ldisc_receive,
391 .write_wakeup = ldisc_tx_wakeup
392 };
393
394 static int register_ldisc(void)
395 {
396 int result;
397
398 result = tty_register_ldisc(N_CAIF, &caif_ldisc);
399 if (result < 0) {
400 pr_err("cannot register CAIF ldisc=%d err=%d\n", N_CAIF,
401 result);
402 return result;
403 }
404 return result;
405 }
406 static const struct net_device_ops netdev_ops = {
407 .ndo_open = caif_net_open,
408 .ndo_stop = caif_net_close,
409 .ndo_start_xmit = caif_xmit
410 };
411
412 static void caifdev_setup(struct net_device *dev)
413 {
414 struct ser_device *serdev = netdev_priv(dev);
415
416 dev->features = 0;
417 dev->netdev_ops = &netdev_ops;
418 dev->type = ARPHRD_CAIF;
419 dev->flags = IFF_POINTOPOINT | IFF_NOARP;
420 dev->mtu = CAIF_MAX_MTU;
421 dev->priv_flags |= IFF_NO_QUEUE;
422 dev->needs_free_netdev = true;
423 skb_queue_head_init(&serdev->head);
424 serdev->common.link_select = CAIF_LINK_LOW_LATENCY;
425 serdev->common.use_frag = true;
426 serdev->common.use_stx = ser_use_stx;
427 serdev->common.use_fcs = ser_use_fcs;
428 serdev->dev = dev;
429 }
430
431
432 static int caif_net_open(struct net_device *dev)
433 {
434 netif_wake_queue(dev);
435 return 0;
436 }
437
438 static int caif_net_close(struct net_device *dev)
439 {
440 netif_stop_queue(dev);
441 return 0;
442 }
443
444 static int __init caif_ser_init(void)
445 {
446 int ret;
447
448 ret = register_ldisc();
449 debugfsdir = debugfs_create_dir("caif_serial", NULL);
450 return ret;
451 }
452
453 static void __exit caif_ser_exit(void)
454 {
455 spin_lock(&ser_lock);
456 list_splice(&ser_list, &ser_release_list);
457 spin_unlock(&ser_lock);
458 ser_release(NULL);
459 cancel_work_sync(&ser_release_work);
460 tty_unregister_ldisc(N_CAIF);
461 debugfs_remove_recursive(debugfsdir);
462 }
463
464 module_init(caif_ser_init);
465 module_exit(caif_ser_exit);
Linux with added FPC-III support