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