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Sjur Braendeland9b271052010-03-30 13:56:30 +00001/*
2 * Copyright (C) ST-Ericsson AB 2010
3 * Author: Sjur Brendeland / sjur.brandeland@stericsson.com
4 * License terms: GNU General Public License (GPL) version 2
5 */
6
Alexey Dobriyana6b7a402011-06-06 10:43:46 +00007#include <linux/hardirq.h>
Sjur Braendeland9b271052010-03-30 13:56:30 +00008#include <linux/init.h>
Sjur Braendeland9b271052010-03-30 13:56:30 +00009#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<sjur.brandeland@stericsson.com>");
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 /* 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/*This list is protected by the rtnl lock. */
39static LIST_HEAD(ser_list);
40
Rusty Russelleb939922011-12-19 14:08:01 +000041static bool ser_loop;
Sjur Braendeland9b271052010-03-30 13:56:30 +000042module_param(ser_loop, bool, S_IRUGO);
43MODULE_PARM_DESC(ser_loop, "Run in simulated loopback mode.");
44
Rusty Russelleb939922011-12-19 14:08:01 +000045static bool ser_use_stx = true;
Sjur Braendeland9b271052010-03-30 13:56:30 +000046module_param(ser_use_stx, bool, S_IRUGO);
47MODULE_PARM_DESC(ser_use_stx, "STX enabled or not.");
48
Rusty Russelleb939922011-12-19 14:08:01 +000049static bool ser_use_fcs = true;
Sjur Braendeland9b271052010-03-30 13:56:30 +000050
51module_param(ser_use_fcs, bool, S_IRUGO);
52MODULE_PARM_DESC(ser_use_fcs, "FCS enabled or not.");
53
54static int ser_write_chunk = MAX_WRITE_CHUNK;
55module_param(ser_write_chunk, int, S_IRUGO);
56
57MODULE_PARM_DESC(ser_write_chunk, "Maximum size of data written to UART.");
58
59static struct dentry *debugfsdir;
60
61static int caif_net_open(struct net_device *dev);
62static int caif_net_close(struct net_device *dev);
63
64struct ser_device {
65 struct caif_dev_common common;
66 struct list_head node;
67 struct net_device *dev;
68 struct sk_buff_head head;
69 struct tty_struct *tty;
70 bool tx_started;
71 unsigned long state;
72 char *tty_name;
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->hw_stopped << 4 |
92 ser->tty->flow_stopped << 3 |
93 ser->tty->packet << 2 |
Jiri Slabyd6c53c02013-01-03 15:53:05 +010094 ser->tty->port->low_latency << 1 |
Sjur Braendeland9b271052010-03-30 13:56:30 +000095 ser->tty->warned;
96}
97static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty)
98{
99 ser->debugfs_tty_dir =
100 debugfs_create_dir(tty->name, debugfsdir);
101 if (!IS_ERR(ser->debugfs_tty_dir)) {
102 debugfs_create_blob("last_tx_msg", S_IRUSR,
103 ser->debugfs_tty_dir,
104 &ser->tx_blob);
105
106 debugfs_create_blob("last_rx_msg", S_IRUSR,
107 ser->debugfs_tty_dir,
108 &ser->rx_blob);
109
110 debugfs_create_x32("ser_state", S_IRUSR,
111 ser->debugfs_tty_dir,
112 (u32 *)&ser->state);
113
114 debugfs_create_x8("tty_status", S_IRUSR,
115 ser->debugfs_tty_dir,
116 &ser->tty_status);
117
118 }
119 ser->tx_blob.data = ser->tx_data;
120 ser->tx_blob.size = 0;
121 ser->rx_blob.data = ser->rx_data;
122 ser->rx_blob.size = 0;
123}
124
125static inline void debugfs_deinit(struct ser_device *ser)
126{
127 debugfs_remove_recursive(ser->debugfs_tty_dir);
128}
129
130static inline void debugfs_rx(struct ser_device *ser, const u8 *data, int size)
131{
132 if (size > sizeof(ser->rx_data))
133 size = sizeof(ser->rx_data);
134 memcpy(ser->rx_data, data, size);
135 ser->rx_blob.data = ser->rx_data;
136 ser->rx_blob.size = size;
137}
138
139static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size)
140{
141 if (size > sizeof(ser->tx_data))
142 size = sizeof(ser->tx_data);
143 memcpy(ser->tx_data, data, size);
144 ser->tx_blob.data = ser->tx_data;
145 ser->tx_blob.size = size;
146}
147#else
148static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty)
149{
150}
151
152static inline void debugfs_deinit(struct ser_device *ser)
153{
154}
155
156static inline void update_tty_status(struct ser_device *ser)
157{
158}
159
160static inline void debugfs_rx(struct ser_device *ser, const u8 *data, int size)
161{
162}
163
164static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size)
165{
166}
167
168#endif
169
Linus Torvalds55db4c62011-06-04 06:33:24 +0900170static void ldisc_receive(struct tty_struct *tty, const u8 *data,
171 char *flags, int count)
Sjur Braendeland9b271052010-03-30 13:56:30 +0000172{
173 struct sk_buff *skb = NULL;
174 struct ser_device *ser;
175 int ret;
176 u8 *p;
Dan Carpenterc1f8fc52010-05-31 21:09:33 +0000177
Sjur Braendeland9b271052010-03-30 13:56:30 +0000178 ser = tty->disc_data;
179
180 /*
181 * NOTE: flags may contain information about break or overrun.
182 * This is not yet handled.
183 */
184
185
186 /*
187 * Workaround for garbage at start of transmission,
188 * only enable if STX handling is not enabled.
189 */
190 if (!ser->common.use_stx && !ser->tx_started) {
191 dev_info(&ser->dev->dev,
192 "Bytes received before initial transmission -"
193 "bytes discarded.\n");
194 return;
195 }
196
197 BUG_ON(ser->dev == NULL);
198
199 /* Get a suitable caif packet and copy in data. */
200 skb = netdev_alloc_skb(ser->dev, count+1);
Sjur Braendelandd3f744e2010-04-28 08:54:34 +0000201 if (skb == NULL)
202 return;
Sjur Braendeland9b271052010-03-30 13:56:30 +0000203 p = skb_put(skb, count);
204 memcpy(p, data, count);
205
206 skb->protocol = htons(ETH_P_CAIF);
207 skb_reset_mac_header(skb);
208 skb->dev = ser->dev;
209 debugfs_rx(ser, data, count);
210 /* Push received packet up the stack. */
211 ret = netif_rx_ni(skb);
212 if (!ret) {
213 ser->dev->stats.rx_packets++;
214 ser->dev->stats.rx_bytes += count;
215 } else
216 ++ser->dev->stats.rx_dropped;
217 update_tty_status(ser);
218}
219
220static int handle_tx(struct ser_device *ser)
221{
222 struct tty_struct *tty;
223 struct sk_buff *skb;
224 int tty_wr, len, room;
Dan Carpenterc1f8fc52010-05-31 21:09:33 +0000225
Sjur Braendeland9b271052010-03-30 13:56:30 +0000226 tty = ser->tty;
227 ser->tx_started = true;
228
229 /* Enter critical section */
230 if (test_and_set_bit(CAIF_SENDING, &ser->state))
231 return 0;
232
233 /* skb_peek is safe because handle_tx is called after skb_queue_tail */
234 while ((skb = skb_peek(&ser->head)) != NULL) {
235
236 /* Make sure you don't write too much */
237 len = skb->len;
238 room = tty_write_room(tty);
239 if (!room)
240 break;
241 if (room > ser_write_chunk)
242 room = ser_write_chunk;
243 if (len > room)
244 len = room;
245
246 /* Write to tty or loopback */
247 if (!ser_loop) {
248 tty_wr = tty->ops->write(tty, skb->data, len);
249 update_tty_status(ser);
250 } else {
251 tty_wr = len;
252 ldisc_receive(tty, skb->data, NULL, len);
253 }
254 ser->dev->stats.tx_packets++;
255 ser->dev->stats.tx_bytes += tty_wr;
256
257 /* Error on TTY ?! */
258 if (tty_wr < 0)
259 goto error;
260 /* Reduce buffer written, and discard if empty */
261 skb_pull(skb, tty_wr);
262 if (skb->len == 0) {
263 struct sk_buff *tmp = skb_dequeue(&ser->head);
Roar Førdef84ea772011-12-06 12:15:44 +0000264 WARN_ON(tmp != skb);
Sjur Braendeland9b271052010-03-30 13:56:30 +0000265 if (in_interrupt())
266 dev_kfree_skb_irq(skb);
267 else
268 kfree_skb(skb);
269 }
270 }
271 /* Send flow off if queue is empty */
272 if (ser->head.qlen <= SEND_QUEUE_LOW &&
273 test_and_clear_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
274 ser->common.flowctrl != NULL)
275 ser->common.flowctrl(ser->dev, ON);
276 clear_bit(CAIF_SENDING, &ser->state);
277 return 0;
278error:
279 clear_bit(CAIF_SENDING, &ser->state);
280 return tty_wr;
281}
282
283static int caif_xmit(struct sk_buff *skb, struct net_device *dev)
284{
285 struct ser_device *ser;
Dan Carpenterc1f8fc52010-05-31 21:09:33 +0000286
Sjur Braendeland9b271052010-03-30 13:56:30 +0000287 BUG_ON(dev == NULL);
288 ser = netdev_priv(dev);
289
290 /* Send flow off once, on high water mark */
291 if (ser->head.qlen > SEND_QUEUE_HIGH &&
292 !test_and_set_bit(CAIF_FLOW_OFF_SENT, &ser->state) &&
293 ser->common.flowctrl != NULL)
294
295 ser->common.flowctrl(ser->dev, OFF);
296
297 skb_queue_tail(&ser->head, skb);
298 return handle_tx(ser);
299}
300
301
302static void ldisc_tx_wakeup(struct tty_struct *tty)
303{
304 struct ser_device *ser;
Dan Carpenterc1f8fc52010-05-31 21:09:33 +0000305
Sjur Braendeland9b271052010-03-30 13:56:30 +0000306 ser = tty->disc_data;
307 BUG_ON(ser == NULL);
Roar Førdef84ea772011-12-06 12:15:44 +0000308 WARN_ON(ser->tty != tty);
Sjur Braendeland9b271052010-03-30 13:56:30 +0000309 handle_tx(ser);
310}
311
312
313static int ldisc_open(struct tty_struct *tty)
314{
315 struct ser_device *ser;
316 struct net_device *dev;
317 char name[64];
318 int result;
319
Alan Coxc93f0942010-04-07 16:49:31 -0700320 /* No write no play */
321 if (tty->ops->write == NULL)
322 return -EOPNOTSUPP;
Sjur Braendelandd3f744e2010-04-28 08:54:34 +0000323 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_TTY_CONFIG))
324 return -EPERM;
Alan Coxc93f0942010-04-07 16:49:31 -0700325
Sjur Braendeland9b271052010-03-30 13:56:30 +0000326 sprintf(name, "cf%s", tty->name);
327 dev = alloc_netdev(sizeof(*ser), name, caifdev_setup);
Alan Coxc66b9b72012-07-24 02:42:14 +0000328 if (!dev)
329 return -ENOMEM;
330
Sjur Braendeland9b271052010-03-30 13:56:30 +0000331 ser = netdev_priv(dev);
Alan Coxe31d5a02010-04-07 16:50:00 -0700332 ser->tty = tty_kref_get(tty);
Sjur Braendeland9b271052010-03-30 13:56:30 +0000333 ser->dev = dev;
334 debugfs_init(ser, tty);
335 tty->receive_room = N_TTY_BUF_SIZE;
336 tty->disc_data = ser;
337 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
338 rtnl_lock();
339 result = register_netdevice(dev);
340 if (result) {
341 rtnl_unlock();
342 free_netdev(dev);
343 return -ENODEV;
344 }
345
346 list_add(&ser->node, &ser_list);
347 rtnl_unlock();
348 netif_stop_queue(dev);
349 update_tty_status(ser);
350 return 0;
351}
352
353static void ldisc_close(struct tty_struct *tty)
354{
355 struct ser_device *ser = tty->disc_data;
356 /* Remove may be called inside or outside of rtnl_lock */
357 int islocked = rtnl_is_locked();
Dan Carpenterc1f8fc52010-05-31 21:09:33 +0000358
Sjur Braendeland9b271052010-03-30 13:56:30 +0000359 if (!islocked)
360 rtnl_lock();
361 /* device is freed automagically by net-sysfs */
362 dev_close(ser->dev);
363 unregister_netdevice(ser->dev);
364 list_del(&ser->node);
365 debugfs_deinit(ser);
Alan Coxe31d5a02010-04-07 16:50:00 -0700366 tty_kref_put(ser->tty);
Sjur Braendeland9b271052010-03-30 13:56:30 +0000367 if (!islocked)
368 rtnl_unlock();
369}
370
371/* The line discipline structure. */
372static struct tty_ldisc_ops caif_ldisc = {
373 .owner = THIS_MODULE,
374 .magic = TTY_LDISC_MAGIC,
375 .name = "n_caif",
376 .open = ldisc_open,
377 .close = ldisc_close,
378 .receive_buf = ldisc_receive,
379 .write_wakeup = ldisc_tx_wakeup
380};
381
382static int register_ldisc(void)
383{
384 int result;
Dan Carpenterc1f8fc52010-05-31 21:09:33 +0000385
Sjur Braendeland9b271052010-03-30 13:56:30 +0000386 result = tty_register_ldisc(N_CAIF, &caif_ldisc);
387 if (result < 0) {
388 pr_err("cannot register CAIF ldisc=%d err=%d\n", N_CAIF,
389 result);
390 return result;
391 }
392 return result;
393}
394static const struct net_device_ops netdev_ops = {
395 .ndo_open = caif_net_open,
396 .ndo_stop = caif_net_close,
397 .ndo_start_xmit = caif_xmit
398};
399
400static void caifdev_setup(struct net_device *dev)
401{
402 struct ser_device *serdev = netdev_priv(dev);
Dan Carpenterc1f8fc52010-05-31 21:09:33 +0000403
Sjur Braendeland9b271052010-03-30 13:56:30 +0000404 dev->features = 0;
405 dev->netdev_ops = &netdev_ops;
406 dev->type = ARPHRD_CAIF;
407 dev->flags = IFF_POINTOPOINT | IFF_NOARP;
408 dev->mtu = CAIF_MAX_MTU;
Sjur Braendeland9b271052010-03-30 13:56:30 +0000409 dev->tx_queue_len = 0;
410 dev->destructor = free_netdev;
411 skb_queue_head_init(&serdev->head);
412 serdev->common.link_select = CAIF_LINK_LOW_LATENCY;
413 serdev->common.use_frag = true;
414 serdev->common.use_stx = ser_use_stx;
415 serdev->common.use_fcs = ser_use_fcs;
416 serdev->dev = dev;
417}
418
419
420static int caif_net_open(struct net_device *dev)
421{
Sjur Braendeland9b271052010-03-30 13:56:30 +0000422 netif_wake_queue(dev);
423 return 0;
424}
425
426static int caif_net_close(struct net_device *dev)
427{
428 netif_stop_queue(dev);
429 return 0;
430}
431
432static int __init caif_ser_init(void)
433{
434 int ret;
Dan Carpenterc1f8fc52010-05-31 21:09:33 +0000435
Sjur Braendeland9b271052010-03-30 13:56:30 +0000436 ret = register_ldisc();
437 debugfsdir = debugfs_create_dir("caif_serial", NULL);
438 return ret;
439}
440
441static void __exit caif_ser_exit(void)
442{
443 struct ser_device *ser = NULL;
444 struct list_head *node;
445 struct list_head *_tmp;
Dan Carpenterc1f8fc52010-05-31 21:09:33 +0000446
Sjur Braendeland9b271052010-03-30 13:56:30 +0000447 list_for_each_safe(node, _tmp, &ser_list) {
448 ser = list_entry(node, struct ser_device, node);
449 dev_close(ser->dev);
450 unregister_netdevice(ser->dev);
451 list_del(node);
452 }
453 tty_unregister_ldisc(N_CAIF);
454 debugfs_remove_recursive(debugfsdir);
455}
456
457module_init(caif_ser_init);
458module_exit(caif_ser_exit);