1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * ssi_protocol.c
4  *
5  * Implementation of the SSI McSAAB improved protocol.
6  *
7  * Copyright (C) 2010 Nokia Corporation. All rights reserved.
8  * Copyright (C) 2013 Sebastian Reichel <sre@kernel.org>
9  *
10  * Contact: Carlos Chinea <carlos.chinea@nokia.com>
11  */
12 
13 #include <linux/atomic.h>
14 #include <linux/clk.h>
15 #include <linux/device.h>
16 #include <linux/err.h>
17 #include <linux/gpio.h>
18 #include <linux/if_ether.h>
19 #include <linux/if_arp.h>
20 #include <linux/if_phonet.h>
21 #include <linux/init.h>
22 #include <linux/irq.h>
23 #include <linux/list.h>
24 #include <linux/module.h>
25 #include <linux/netdevice.h>
26 #include <linux/notifier.h>
27 #include <linux/scatterlist.h>
28 #include <linux/skbuff.h>
29 #include <linux/slab.h>
30 #include <linux/spinlock.h>
31 #include <linux/timer.h>
32 #include <linux/hsi/hsi.h>
33 #include <linux/hsi/ssi_protocol.h>
34 
35 void ssi_waketest(struct hsi_client *cl, unsigned int enable);
36 
37 #define SSIP_TXQUEUE_LEN	100
38 #define SSIP_MAX_MTU		65535
39 #define SSIP_DEFAULT_MTU	4000
40 #define PN_MEDIA_SOS		21
41 #define SSIP_MIN_PN_HDR		6	/* FIXME: Revisit */
42 #define SSIP_WDTOUT		2000	/* FIXME: has to be 500 msecs */
43 #define SSIP_KATOUT		15	/* 15 msecs */
44 #define SSIP_MAX_CMDS		5 /* Number of pre-allocated commands buffers */
45 #define SSIP_BYTES_TO_FRAMES(x) ((((x) - 1) >> 2) + 1)
46 #define SSIP_CMT_LOADER_SYNC	0x11223344
47 /*
48  * SSI protocol command definitions
49  */
50 #define SSIP_COMMAND(data)	((data) >> 28)
51 #define SSIP_PAYLOAD(data)	((data) & 0xfffffff)
52 /* Commands */
53 #define SSIP_SW_BREAK		0
54 #define SSIP_BOOTINFO_REQ	1
55 #define SSIP_BOOTINFO_RESP	2
56 #define SSIP_WAKETEST_RESULT	3
57 #define SSIP_START_TRANS	4
58 #define SSIP_READY		5
59 /* Payloads */
60 #define SSIP_DATA_VERSION(data)	((data) & 0xff)
61 #define SSIP_LOCAL_VERID	1
62 #define SSIP_WAKETEST_OK	0
63 #define SSIP_WAKETEST_FAILED	1
64 #define SSIP_PDU_LENGTH(data)	(((data) >> 8) & 0xffff)
65 #define SSIP_MSG_ID(data)	((data) & 0xff)
66 /* Generic Command */
67 #define SSIP_CMD(cmd, payload)	(((cmd) << 28) | ((payload) & 0xfffffff))
68 /* Commands for the control channel */
69 #define SSIP_BOOTINFO_REQ_CMD(ver) \
70 		SSIP_CMD(SSIP_BOOTINFO_REQ, SSIP_DATA_VERSION(ver))
71 #define SSIP_BOOTINFO_RESP_CMD(ver) \
72 		SSIP_CMD(SSIP_BOOTINFO_RESP, SSIP_DATA_VERSION(ver))
73 #define SSIP_START_TRANS_CMD(pdulen, id) \
74 		SSIP_CMD(SSIP_START_TRANS, (((pdulen) << 8) | SSIP_MSG_ID(id)))
75 #define SSIP_READY_CMD		SSIP_CMD(SSIP_READY, 0)
76 #define SSIP_SWBREAK_CMD	SSIP_CMD(SSIP_SW_BREAK, 0)
77 
78 #define SSIP_WAKETEST_FLAG 0
79 
80 /* Main state machine states */
81 enum {
82 	INIT,
83 	HANDSHAKE,
84 	ACTIVE,
85 };
86 
87 /* Send state machine states */
88 enum {
89 	SEND_IDLE,
90 	WAIT4READY,
91 	SEND_READY,
92 	SENDING,
93 	SENDING_SWBREAK,
94 };
95 
96 /* Receive state machine states */
97 enum {
98 	RECV_IDLE,
99 	RECV_READY,
100 	RECEIVING,
101 };
102 
103 /**
104  * struct ssi_protocol - SSI protocol (McSAAB) data
105  * @main_state: Main state machine
106  * @send_state: TX state machine
107  * @recv_state: RX state machine
108  * @flags: Flags, currently only used to follow wake line test
109  * @rxid: RX data id
110  * @txid: TX data id
111  * @txqueue_len: TX queue length
112  * @tx_wd: TX watchdog
113  * @rx_wd: RX watchdog
114  * @keep_alive: Workaround for SSI HW bug
115  * @lock: To serialize access to this struct
116  * @netdev: Phonet network device
117  * @txqueue: TX data queue
118  * @cmdqueue: Queue of free commands
119  * @cl: HSI client own reference
120  * @link: Link for ssip_list
121  * @tx_usecount: Refcount to keep track the slaves that use the wake line
122  * @channel_id_cmd: HSI channel id for command stream
123  * @channel_id_data: HSI channel id for data stream
124  */
125 struct ssi_protocol {
126 	unsigned int		main_state;
127 	unsigned int		send_state;
128 	unsigned int		recv_state;
129 	unsigned long		flags;
130 	u8			rxid;
131 	u8			txid;
132 	unsigned int		txqueue_len;
133 	struct timer_list	tx_wd;
134 	struct timer_list	rx_wd;
135 	struct timer_list	keep_alive; /* wake-up workaround */
136 	spinlock_t		lock;
137 	struct net_device	*netdev;
138 	struct list_head	txqueue;
139 	struct list_head	cmdqueue;
140 	struct work_struct	work;
141 	struct hsi_client	*cl;
142 	struct list_head	link;
143 	atomic_t		tx_usecnt;
144 	int			channel_id_cmd;
145 	int			channel_id_data;
146 };
147 
148 /* List of ssi protocol instances */
149 static LIST_HEAD(ssip_list);
150 
151 static void ssip_rxcmd_complete(struct hsi_msg *msg);
152 
153 static inline void ssip_set_cmd(struct hsi_msg *msg, u32 cmd)
154 {
155 	u32 *data;
156 
157 	data = sg_virt(msg->sgt.sgl);
158 	*data = cmd;
159 }
160 
161 static inline u32 ssip_get_cmd(struct hsi_msg *msg)
162 {
163 	u32 *data;
164 
165 	data = sg_virt(msg->sgt.sgl);
166 
167 	return *data;
168 }
169 
170 static void ssip_skb_to_msg(struct sk_buff *skb, struct hsi_msg *msg)
171 {
172 	skb_frag_t *frag;
173 	struct scatterlist *sg;
174 	int i;
175 
176 	BUG_ON(msg->sgt.nents != (unsigned int)(skb_shinfo(skb)->nr_frags + 1));
177 
178 	sg = msg->sgt.sgl;
179 	sg_set_buf(sg, skb->data, skb_headlen(skb));
180 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
181 		sg = sg_next(sg);
182 		BUG_ON(!sg);
183 		frag = &skb_shinfo(skb)->frags[i];
184 		sg_set_page(sg, skb_frag_page(frag), skb_frag_size(frag),
185 				skb_frag_off(frag));
186 	}
187 }
188 
189 static void ssip_free_data(struct hsi_msg *msg)
190 {
191 	struct sk_buff *skb;
192 
193 	skb = msg->context;
194 	pr_debug("free data: msg %p context %p skb %p\n", msg, msg->context,
195 								skb);
196 	msg->destructor = NULL;
197 	dev_kfree_skb(skb);
198 	hsi_free_msg(msg);
199 }
200 
201 static struct hsi_msg *ssip_alloc_data(struct ssi_protocol *ssi,
202 					struct sk_buff *skb, gfp_t flags)
203 {
204 	struct hsi_msg *msg;
205 
206 	msg = hsi_alloc_msg(skb_shinfo(skb)->nr_frags + 1, flags);
207 	if (!msg)
208 		return NULL;
209 	ssip_skb_to_msg(skb, msg);
210 	msg->destructor = ssip_free_data;
211 	msg->channel = ssi->channel_id_data;
212 	msg->context = skb;
213 
214 	return msg;
215 }
216 
217 static inline void ssip_release_cmd(struct hsi_msg *msg)
218 {
219 	struct ssi_protocol *ssi = hsi_client_drvdata(msg->cl);
220 
221 	dev_dbg(&msg->cl->device, "Release cmd 0x%08x\n", ssip_get_cmd(msg));
222 	spin_lock_bh(&ssi->lock);
223 	list_add_tail(&msg->link, &ssi->cmdqueue);
224 	spin_unlock_bh(&ssi->lock);
225 }
226 
227 static struct hsi_msg *ssip_claim_cmd(struct ssi_protocol *ssi)
228 {
229 	struct hsi_msg *msg;
230 
231 	BUG_ON(list_empty(&ssi->cmdqueue));
232 
233 	spin_lock_bh(&ssi->lock);
234 	msg = list_first_entry(&ssi->cmdqueue, struct hsi_msg, link);
235 	list_del(&msg->link);
236 	spin_unlock_bh(&ssi->lock);
237 	msg->destructor = ssip_release_cmd;
238 
239 	return msg;
240 }
241 
242 static void ssip_free_cmds(struct ssi_protocol *ssi)
243 {
244 	struct hsi_msg *msg, *tmp;
245 
246 	list_for_each_entry_safe(msg, tmp, &ssi->cmdqueue, link) {
247 		list_del(&msg->link);
248 		msg->destructor = NULL;
249 		kfree(sg_virt(msg->sgt.sgl));
250 		hsi_free_msg(msg);
251 	}
252 }
253 
254 static int ssip_alloc_cmds(struct ssi_protocol *ssi)
255 {
256 	struct hsi_msg *msg;
257 	u32 *buf;
258 	unsigned int i;
259 
260 	for (i = 0; i < SSIP_MAX_CMDS; i++) {
261 		msg = hsi_alloc_msg(1, GFP_KERNEL);
262 		if (!msg)
263 			goto out;
264 		buf = kmalloc(sizeof(*buf), GFP_KERNEL);
265 		if (!buf) {
266 			hsi_free_msg(msg);
267 			goto out;
268 		}
269 		sg_init_one(msg->sgt.sgl, buf, sizeof(*buf));
270 		msg->channel = ssi->channel_id_cmd;
271 		list_add_tail(&msg->link, &ssi->cmdqueue);
272 	}
273 
274 	return 0;
275 out:
276 	ssip_free_cmds(ssi);
277 
278 	return -ENOMEM;
279 }
280 
281 static void ssip_set_rxstate(struct ssi_protocol *ssi, unsigned int state)
282 {
283 	ssi->recv_state = state;
284 	switch (state) {
285 	case RECV_IDLE:
286 		del_timer(&ssi->rx_wd);
287 		if (ssi->send_state == SEND_IDLE)
288 			del_timer(&ssi->keep_alive);
289 		break;
290 	case RECV_READY:
291 		/* CMT speech workaround */
292 		if (atomic_read(&ssi->tx_usecnt))
293 			break;
294 		fallthrough;
295 	case RECEIVING:
296 		mod_timer(&ssi->keep_alive, jiffies +
297 						msecs_to_jiffies(SSIP_KATOUT));
298 		mod_timer(&ssi->rx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
299 		break;
300 	default:
301 		break;
302 	}
303 }
304 
305 static void ssip_set_txstate(struct ssi_protocol *ssi, unsigned int state)
306 {
307 	ssi->send_state = state;
308 	switch (state) {
309 	case SEND_IDLE:
310 	case SEND_READY:
311 		del_timer(&ssi->tx_wd);
312 		if (ssi->recv_state == RECV_IDLE)
313 			del_timer(&ssi->keep_alive);
314 		break;
315 	case WAIT4READY:
316 	case SENDING:
317 	case SENDING_SWBREAK:
318 		mod_timer(&ssi->keep_alive,
319 				jiffies + msecs_to_jiffies(SSIP_KATOUT));
320 		mod_timer(&ssi->tx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
321 		break;
322 	default:
323 		break;
324 	}
325 }
326 
327 struct hsi_client *ssip_slave_get_master(struct hsi_client *slave)
328 {
329 	struct hsi_client *master = ERR_PTR(-ENODEV);
330 	struct ssi_protocol *ssi;
331 
332 	list_for_each_entry(ssi, &ssip_list, link)
333 		if (slave->device.parent == ssi->cl->device.parent) {
334 			master = ssi->cl;
335 			break;
336 		}
337 
338 	return master;
339 }
340 EXPORT_SYMBOL_GPL(ssip_slave_get_master);
341 
342 int ssip_slave_start_tx(struct hsi_client *master)
343 {
344 	struct ssi_protocol *ssi = hsi_client_drvdata(master);
345 
346 	dev_dbg(&master->device, "start TX %d\n", atomic_read(&ssi->tx_usecnt));
347 	spin_lock_bh(&ssi->lock);
348 	if (ssi->send_state == SEND_IDLE) {
349 		ssip_set_txstate(ssi, WAIT4READY);
350 		hsi_start_tx(master);
351 	}
352 	spin_unlock_bh(&ssi->lock);
353 	atomic_inc(&ssi->tx_usecnt);
354 
355 	return 0;
356 }
357 EXPORT_SYMBOL_GPL(ssip_slave_start_tx);
358 
359 int ssip_slave_stop_tx(struct hsi_client *master)
360 {
361 	struct ssi_protocol *ssi = hsi_client_drvdata(master);
362 
363 	WARN_ON_ONCE(atomic_read(&ssi->tx_usecnt) == 0);
364 
365 	if (atomic_dec_and_test(&ssi->tx_usecnt)) {
366 		spin_lock_bh(&ssi->lock);
367 		if ((ssi->send_state == SEND_READY) ||
368 			(ssi->send_state == WAIT4READY)) {
369 			ssip_set_txstate(ssi, SEND_IDLE);
370 			hsi_stop_tx(master);
371 		}
372 		spin_unlock_bh(&ssi->lock);
373 	}
374 	dev_dbg(&master->device, "stop TX %d\n", atomic_read(&ssi->tx_usecnt));
375 
376 	return 0;
377 }
378 EXPORT_SYMBOL_GPL(ssip_slave_stop_tx);
379 
380 int ssip_slave_running(struct hsi_client *master)
381 {
382 	struct ssi_protocol *ssi = hsi_client_drvdata(master);
383 	return netif_running(ssi->netdev);
384 }
385 EXPORT_SYMBOL_GPL(ssip_slave_running);
386 
387 static void ssip_reset(struct hsi_client *cl)
388 {
389 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
390 	struct list_head *head, *tmp;
391 	struct hsi_msg *msg;
392 
393 	if (netif_running(ssi->netdev))
394 		netif_carrier_off(ssi->netdev);
395 	hsi_flush(cl);
396 	spin_lock_bh(&ssi->lock);
397 	if (ssi->send_state != SEND_IDLE)
398 		hsi_stop_tx(cl);
399 	spin_unlock_bh(&ssi->lock);
400 	if (test_and_clear_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
401 		ssi_waketest(cl, 0); /* FIXME: To be removed */
402 	spin_lock_bh(&ssi->lock);
403 	del_timer(&ssi->rx_wd);
404 	del_timer(&ssi->tx_wd);
405 	del_timer(&ssi->keep_alive);
406 	ssi->main_state = 0;
407 	ssi->send_state = 0;
408 	ssi->recv_state = 0;
409 	ssi->flags = 0;
410 	ssi->rxid = 0;
411 	ssi->txid = 0;
412 	list_for_each_safe(head, tmp, &ssi->txqueue) {
413 		msg = list_entry(head, struct hsi_msg, link);
414 		dev_dbg(&cl->device, "Pending TX data\n");
415 		list_del(head);
416 		ssip_free_data(msg);
417 	}
418 	ssi->txqueue_len = 0;
419 	spin_unlock_bh(&ssi->lock);
420 }
421 
422 static void ssip_dump_state(struct hsi_client *cl)
423 {
424 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
425 	struct hsi_msg *msg;
426 
427 	spin_lock_bh(&ssi->lock);
428 	dev_err(&cl->device, "Main state: %d\n", ssi->main_state);
429 	dev_err(&cl->device, "Recv state: %d\n", ssi->recv_state);
430 	dev_err(&cl->device, "Send state: %d\n", ssi->send_state);
431 	dev_err(&cl->device, "CMT %s\n", (ssi->main_state == ACTIVE) ?
432 							"Online" : "Offline");
433 	dev_err(&cl->device, "Wake test %d\n",
434 				test_bit(SSIP_WAKETEST_FLAG, &ssi->flags));
435 	dev_err(&cl->device, "Data RX id: %d\n", ssi->rxid);
436 	dev_err(&cl->device, "Data TX id: %d\n", ssi->txid);
437 
438 	list_for_each_entry(msg, &ssi->txqueue, link)
439 		dev_err(&cl->device, "pending TX data (%p)\n", msg);
440 	spin_unlock_bh(&ssi->lock);
441 }
442 
443 static void ssip_error(struct hsi_client *cl)
444 {
445 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
446 	struct hsi_msg *msg;
447 
448 	ssip_dump_state(cl);
449 	ssip_reset(cl);
450 	msg = ssip_claim_cmd(ssi);
451 	msg->complete = ssip_rxcmd_complete;
452 	hsi_async_read(cl, msg);
453 }
454 
455 static void ssip_keep_alive(struct timer_list *t)
456 {
457 	struct ssi_protocol *ssi = from_timer(ssi, t, keep_alive);
458 	struct hsi_client *cl = ssi->cl;
459 
460 	dev_dbg(&cl->device, "Keep alive kick in: m(%d) r(%d) s(%d)\n",
461 		ssi->main_state, ssi->recv_state, ssi->send_state);
462 
463 	spin_lock(&ssi->lock);
464 	if (ssi->recv_state == RECV_IDLE)
465 		switch (ssi->send_state) {
466 		case SEND_READY:
467 			if (atomic_read(&ssi->tx_usecnt) == 0)
468 				break;
469 			fallthrough;
470 			/*
471 			 * Workaround for cmt-speech in that case
472 			 * we relay on audio timers.
473 			 */
474 		case SEND_IDLE:
475 			spin_unlock(&ssi->lock);
476 			return;
477 		}
478 	mod_timer(&ssi->keep_alive, jiffies + msecs_to_jiffies(SSIP_KATOUT));
479 	spin_unlock(&ssi->lock);
480 }
481 
482 static void ssip_rx_wd(struct timer_list *t)
483 {
484 	struct ssi_protocol *ssi = from_timer(ssi, t, rx_wd);
485 	struct hsi_client *cl = ssi->cl;
486 
487 	dev_err(&cl->device, "Watchdog triggered\n");
488 	ssip_error(cl);
489 }
490 
491 static void ssip_tx_wd(struct timer_list *t)
492 {
493 	struct ssi_protocol *ssi = from_timer(ssi, t, tx_wd);
494 	struct hsi_client *cl = ssi->cl;
495 
496 	dev_err(&cl->device, "Watchdog triggered\n");
497 	ssip_error(cl);
498 }
499 
500 static void ssip_send_bootinfo_req_cmd(struct hsi_client *cl)
501 {
502 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
503 	struct hsi_msg *msg;
504 
505 	dev_dbg(&cl->device, "Issuing BOOT INFO REQ command\n");
506 	msg = ssip_claim_cmd(ssi);
507 	ssip_set_cmd(msg, SSIP_BOOTINFO_REQ_CMD(SSIP_LOCAL_VERID));
508 	msg->complete = ssip_release_cmd;
509 	hsi_async_write(cl, msg);
510 	dev_dbg(&cl->device, "Issuing RX command\n");
511 	msg = ssip_claim_cmd(ssi);
512 	msg->complete = ssip_rxcmd_complete;
513 	hsi_async_read(cl, msg);
514 }
515 
516 static void ssip_start_rx(struct hsi_client *cl)
517 {
518 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
519 	struct hsi_msg *msg;
520 
521 	dev_dbg(&cl->device, "RX start M(%d) R(%d)\n", ssi->main_state,
522 						ssi->recv_state);
523 	spin_lock_bh(&ssi->lock);
524 	/*
525 	 * We can have two UP events in a row due to a short low
526 	 * high transition. Therefore we need to ignore the sencond UP event.
527 	 */
528 	if ((ssi->main_state != ACTIVE) || (ssi->recv_state == RECV_READY)) {
529 		spin_unlock_bh(&ssi->lock);
530 		return;
531 	}
532 	ssip_set_rxstate(ssi, RECV_READY);
533 	spin_unlock_bh(&ssi->lock);
534 
535 	msg = ssip_claim_cmd(ssi);
536 	ssip_set_cmd(msg, SSIP_READY_CMD);
537 	msg->complete = ssip_release_cmd;
538 	dev_dbg(&cl->device, "Send READY\n");
539 	hsi_async_write(cl, msg);
540 }
541 
542 static void ssip_stop_rx(struct hsi_client *cl)
543 {
544 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
545 
546 	dev_dbg(&cl->device, "RX stop M(%d)\n", ssi->main_state);
547 	spin_lock_bh(&ssi->lock);
548 	if (likely(ssi->main_state == ACTIVE))
549 		ssip_set_rxstate(ssi, RECV_IDLE);
550 	spin_unlock_bh(&ssi->lock);
551 }
552 
553 static void ssip_free_strans(struct hsi_msg *msg)
554 {
555 	ssip_free_data(msg->context);
556 	ssip_release_cmd(msg);
557 }
558 
559 static void ssip_strans_complete(struct hsi_msg *msg)
560 {
561 	struct hsi_client *cl = msg->cl;
562 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
563 	struct hsi_msg *data;
564 
565 	data = msg->context;
566 	ssip_release_cmd(msg);
567 	spin_lock_bh(&ssi->lock);
568 	ssip_set_txstate(ssi, SENDING);
569 	spin_unlock_bh(&ssi->lock);
570 	hsi_async_write(cl, data);
571 }
572 
573 static int ssip_xmit(struct hsi_client *cl)
574 {
575 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
576 	struct hsi_msg *msg, *dmsg;
577 	struct sk_buff *skb;
578 
579 	spin_lock_bh(&ssi->lock);
580 	if (list_empty(&ssi->txqueue)) {
581 		spin_unlock_bh(&ssi->lock);
582 		return 0;
583 	}
584 	dmsg = list_first_entry(&ssi->txqueue, struct hsi_msg, link);
585 	list_del(&dmsg->link);
586 	ssi->txqueue_len--;
587 	spin_unlock_bh(&ssi->lock);
588 
589 	msg = ssip_claim_cmd(ssi);
590 	skb = dmsg->context;
591 	msg->context = dmsg;
592 	msg->complete = ssip_strans_complete;
593 	msg->destructor = ssip_free_strans;
594 
595 	spin_lock_bh(&ssi->lock);
596 	ssip_set_cmd(msg, SSIP_START_TRANS_CMD(SSIP_BYTES_TO_FRAMES(skb->len),
597 								ssi->txid));
598 	ssi->txid++;
599 	ssip_set_txstate(ssi, SENDING);
600 	spin_unlock_bh(&ssi->lock);
601 
602 	dev_dbg(&cl->device, "Send STRANS (%d frames)\n",
603 						SSIP_BYTES_TO_FRAMES(skb->len));
604 
605 	return hsi_async_write(cl, msg);
606 }
607 
608 /* In soft IRQ context */
609 static void ssip_pn_rx(struct sk_buff *skb)
610 {
611 	struct net_device *dev = skb->dev;
612 
613 	if (unlikely(!netif_running(dev))) {
614 		dev_dbg(&dev->dev, "Drop RX packet\n");
615 		dev->stats.rx_dropped++;
616 		dev_kfree_skb(skb);
617 		return;
618 	}
619 	if (unlikely(!pskb_may_pull(skb, SSIP_MIN_PN_HDR))) {
620 		dev_dbg(&dev->dev, "Error drop RX packet\n");
621 		dev->stats.rx_errors++;
622 		dev->stats.rx_length_errors++;
623 		dev_kfree_skb(skb);
624 		return;
625 	}
626 	dev->stats.rx_packets++;
627 	dev->stats.rx_bytes += skb->len;
628 
629 	/* length field is exchanged in network byte order */
630 	((u16 *)skb->data)[2] = ntohs(((u16 *)skb->data)[2]);
631 	dev_dbg(&dev->dev, "RX length fixed (%04x -> %u)\n",
632 			((u16 *)skb->data)[2], ntohs(((u16 *)skb->data)[2]));
633 
634 	skb->protocol = htons(ETH_P_PHONET);
635 	skb_reset_mac_header(skb);
636 	__skb_pull(skb, 1);
637 	netif_rx(skb);
638 }
639 
640 static void ssip_rx_data_complete(struct hsi_msg *msg)
641 {
642 	struct hsi_client *cl = msg->cl;
643 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
644 	struct sk_buff *skb;
645 
646 	if (msg->status == HSI_STATUS_ERROR) {
647 		dev_err(&cl->device, "RX data error\n");
648 		ssip_free_data(msg);
649 		ssip_error(cl);
650 		return;
651 	}
652 	del_timer(&ssi->rx_wd); /* FIXME: Revisit */
653 	skb = msg->context;
654 	ssip_pn_rx(skb);
655 	hsi_free_msg(msg);
656 }
657 
658 static void ssip_rx_bootinforeq(struct hsi_client *cl, u32 cmd)
659 {
660 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
661 	struct hsi_msg *msg;
662 
663 	/* Workaroud: Ignore CMT Loader message leftover */
664 	if (cmd == SSIP_CMT_LOADER_SYNC)
665 		return;
666 
667 	switch (ssi->main_state) {
668 	case ACTIVE:
669 		dev_err(&cl->device, "Boot info req on active state\n");
670 		ssip_error(cl);
671 		fallthrough;
672 	case INIT:
673 	case HANDSHAKE:
674 		spin_lock_bh(&ssi->lock);
675 		ssi->main_state = HANDSHAKE;
676 		spin_unlock_bh(&ssi->lock);
677 
678 		if (!test_and_set_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
679 			ssi_waketest(cl, 1); /* FIXME: To be removed */
680 
681 		spin_lock_bh(&ssi->lock);
682 		/* Start boot handshake watchdog */
683 		mod_timer(&ssi->tx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
684 		spin_unlock_bh(&ssi->lock);
685 		dev_dbg(&cl->device, "Send BOOTINFO_RESP\n");
686 		if (SSIP_DATA_VERSION(cmd) != SSIP_LOCAL_VERID)
687 			dev_warn(&cl->device, "boot info req verid mismatch\n");
688 		msg = ssip_claim_cmd(ssi);
689 		ssip_set_cmd(msg, SSIP_BOOTINFO_RESP_CMD(SSIP_LOCAL_VERID));
690 		msg->complete = ssip_release_cmd;
691 		hsi_async_write(cl, msg);
692 		break;
693 	default:
694 		dev_dbg(&cl->device, "Wrong state M(%d)\n", ssi->main_state);
695 		break;
696 	}
697 }
698 
699 static void ssip_rx_bootinforesp(struct hsi_client *cl, u32 cmd)
700 {
701 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
702 
703 	if (SSIP_DATA_VERSION(cmd) != SSIP_LOCAL_VERID)
704 		dev_warn(&cl->device, "boot info resp verid mismatch\n");
705 
706 	spin_lock_bh(&ssi->lock);
707 	if (ssi->main_state != ACTIVE)
708 		/* Use tx_wd as a boot watchdog in non ACTIVE state */
709 		mod_timer(&ssi->tx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
710 	else
711 		dev_dbg(&cl->device, "boot info resp ignored M(%d)\n",
712 							ssi->main_state);
713 	spin_unlock_bh(&ssi->lock);
714 }
715 
716 static void ssip_rx_waketest(struct hsi_client *cl, u32 cmd)
717 {
718 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
719 	unsigned int wkres = SSIP_PAYLOAD(cmd);
720 
721 	spin_lock_bh(&ssi->lock);
722 	if (ssi->main_state != HANDSHAKE) {
723 		dev_dbg(&cl->device, "wake lines test ignored M(%d)\n",
724 							ssi->main_state);
725 		spin_unlock_bh(&ssi->lock);
726 		return;
727 	}
728 	spin_unlock_bh(&ssi->lock);
729 
730 	if (test_and_clear_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
731 		ssi_waketest(cl, 0); /* FIXME: To be removed */
732 
733 	spin_lock_bh(&ssi->lock);
734 	ssi->main_state = ACTIVE;
735 	del_timer(&ssi->tx_wd); /* Stop boot handshake timer */
736 	spin_unlock_bh(&ssi->lock);
737 
738 	dev_notice(&cl->device, "WAKELINES TEST %s\n",
739 				wkres & SSIP_WAKETEST_FAILED ? "FAILED" : "OK");
740 	if (wkres & SSIP_WAKETEST_FAILED) {
741 		ssip_error(cl);
742 		return;
743 	}
744 	dev_dbg(&cl->device, "CMT is ONLINE\n");
745 	netif_wake_queue(ssi->netdev);
746 	netif_carrier_on(ssi->netdev);
747 }
748 
749 static void ssip_rx_ready(struct hsi_client *cl)
750 {
751 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
752 
753 	spin_lock_bh(&ssi->lock);
754 	if (unlikely(ssi->main_state != ACTIVE)) {
755 		dev_dbg(&cl->device, "READY on wrong state: S(%d) M(%d)\n",
756 					ssi->send_state, ssi->main_state);
757 		spin_unlock_bh(&ssi->lock);
758 		return;
759 	}
760 	if (ssi->send_state != WAIT4READY) {
761 		dev_dbg(&cl->device, "Ignore spurious READY command\n");
762 		spin_unlock_bh(&ssi->lock);
763 		return;
764 	}
765 	ssip_set_txstate(ssi, SEND_READY);
766 	spin_unlock_bh(&ssi->lock);
767 	ssip_xmit(cl);
768 }
769 
770 static void ssip_rx_strans(struct hsi_client *cl, u32 cmd)
771 {
772 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
773 	struct sk_buff *skb;
774 	struct hsi_msg *msg;
775 	int len = SSIP_PDU_LENGTH(cmd);
776 
777 	dev_dbg(&cl->device, "RX strans: %d frames\n", len);
778 	spin_lock_bh(&ssi->lock);
779 	if (unlikely(ssi->main_state != ACTIVE)) {
780 		dev_err(&cl->device, "START TRANS wrong state: S(%d) M(%d)\n",
781 					ssi->send_state, ssi->main_state);
782 		spin_unlock_bh(&ssi->lock);
783 		return;
784 	}
785 	ssip_set_rxstate(ssi, RECEIVING);
786 	if (unlikely(SSIP_MSG_ID(cmd) != ssi->rxid)) {
787 		dev_err(&cl->device, "START TRANS id %d expected %d\n",
788 					SSIP_MSG_ID(cmd), ssi->rxid);
789 		spin_unlock_bh(&ssi->lock);
790 		goto out1;
791 	}
792 	ssi->rxid++;
793 	spin_unlock_bh(&ssi->lock);
794 	skb = netdev_alloc_skb(ssi->netdev, len * 4);
795 	if (unlikely(!skb)) {
796 		dev_err(&cl->device, "No memory for rx skb\n");
797 		goto out1;
798 	}
799 	skb_put(skb, len * 4);
800 	msg = ssip_alloc_data(ssi, skb, GFP_ATOMIC);
801 	if (unlikely(!msg)) {
802 		dev_err(&cl->device, "No memory for RX data msg\n");
803 		goto out2;
804 	}
805 	msg->complete = ssip_rx_data_complete;
806 	hsi_async_read(cl, msg);
807 
808 	return;
809 out2:
810 	dev_kfree_skb(skb);
811 out1:
812 	ssip_error(cl);
813 }
814 
815 static void ssip_rxcmd_complete(struct hsi_msg *msg)
816 {
817 	struct hsi_client *cl = msg->cl;
818 	u32 cmd = ssip_get_cmd(msg);
819 	unsigned int cmdid = SSIP_COMMAND(cmd);
820 
821 	if (msg->status == HSI_STATUS_ERROR) {
822 		dev_err(&cl->device, "RX error detected\n");
823 		ssip_release_cmd(msg);
824 		ssip_error(cl);
825 		return;
826 	}
827 	hsi_async_read(cl, msg);
828 	dev_dbg(&cl->device, "RX cmd: 0x%08x\n", cmd);
829 	switch (cmdid) {
830 	case SSIP_SW_BREAK:
831 		/* Ignored */
832 		break;
833 	case SSIP_BOOTINFO_REQ:
834 		ssip_rx_bootinforeq(cl, cmd);
835 		break;
836 	case SSIP_BOOTINFO_RESP:
837 		ssip_rx_bootinforesp(cl, cmd);
838 		break;
839 	case SSIP_WAKETEST_RESULT:
840 		ssip_rx_waketest(cl, cmd);
841 		break;
842 	case SSIP_START_TRANS:
843 		ssip_rx_strans(cl, cmd);
844 		break;
845 	case SSIP_READY:
846 		ssip_rx_ready(cl);
847 		break;
848 	default:
849 		dev_warn(&cl->device, "command 0x%08x not supported\n", cmd);
850 		break;
851 	}
852 }
853 
854 static void ssip_swbreak_complete(struct hsi_msg *msg)
855 {
856 	struct hsi_client *cl = msg->cl;
857 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
858 
859 	ssip_release_cmd(msg);
860 	spin_lock_bh(&ssi->lock);
861 	if (list_empty(&ssi->txqueue)) {
862 		if (atomic_read(&ssi->tx_usecnt)) {
863 			ssip_set_txstate(ssi, SEND_READY);
864 		} else {
865 			ssip_set_txstate(ssi, SEND_IDLE);
866 			hsi_stop_tx(cl);
867 		}
868 		spin_unlock_bh(&ssi->lock);
869 	} else {
870 		spin_unlock_bh(&ssi->lock);
871 		ssip_xmit(cl);
872 	}
873 	netif_wake_queue(ssi->netdev);
874 }
875 
876 static void ssip_tx_data_complete(struct hsi_msg *msg)
877 {
878 	struct hsi_client *cl = msg->cl;
879 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
880 	struct hsi_msg *cmsg;
881 
882 	if (msg->status == HSI_STATUS_ERROR) {
883 		dev_err(&cl->device, "TX data error\n");
884 		ssip_error(cl);
885 		goto out;
886 	}
887 	spin_lock_bh(&ssi->lock);
888 	if (list_empty(&ssi->txqueue)) {
889 		ssip_set_txstate(ssi, SENDING_SWBREAK);
890 		spin_unlock_bh(&ssi->lock);
891 		cmsg = ssip_claim_cmd(ssi);
892 		ssip_set_cmd(cmsg, SSIP_SWBREAK_CMD);
893 		cmsg->complete = ssip_swbreak_complete;
894 		dev_dbg(&cl->device, "Send SWBREAK\n");
895 		hsi_async_write(cl, cmsg);
896 	} else {
897 		spin_unlock_bh(&ssi->lock);
898 		ssip_xmit(cl);
899 	}
900 out:
901 	ssip_free_data(msg);
902 }
903 
904 static void ssip_port_event(struct hsi_client *cl, unsigned long event)
905 {
906 	switch (event) {
907 	case HSI_EVENT_START_RX:
908 		ssip_start_rx(cl);
909 		break;
910 	case HSI_EVENT_STOP_RX:
911 		ssip_stop_rx(cl);
912 		break;
913 	default:
914 		return;
915 	}
916 }
917 
918 static int ssip_pn_open(struct net_device *dev)
919 {
920 	struct hsi_client *cl = to_hsi_client(dev->dev.parent);
921 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
922 	int err;
923 
924 	err = hsi_claim_port(cl, 1);
925 	if (err < 0) {
926 		dev_err(&cl->device, "SSI port already claimed\n");
927 		return err;
928 	}
929 	err = hsi_register_port_event(cl, ssip_port_event);
930 	if (err < 0) {
931 		dev_err(&cl->device, "Register HSI port event failed (%d)\n",
932 			err);
933 		hsi_release_port(cl);
934 		return err;
935 	}
936 	dev_dbg(&cl->device, "Configuring SSI port\n");
937 	hsi_setup(cl);
938 
939 	if (!test_and_set_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
940 		ssi_waketest(cl, 1); /* FIXME: To be removed */
941 
942 	spin_lock_bh(&ssi->lock);
943 	ssi->main_state = HANDSHAKE;
944 	spin_unlock_bh(&ssi->lock);
945 
946 	ssip_send_bootinfo_req_cmd(cl);
947 
948 	return 0;
949 }
950 
951 static int ssip_pn_stop(struct net_device *dev)
952 {
953 	struct hsi_client *cl = to_hsi_client(dev->dev.parent);
954 
955 	ssip_reset(cl);
956 	hsi_unregister_port_event(cl);
957 	hsi_release_port(cl);
958 
959 	return 0;
960 }
961 
962 static void ssip_xmit_work(struct work_struct *work)
963 {
964 	struct ssi_protocol *ssi =
965 				container_of(work, struct ssi_protocol, work);
966 	struct hsi_client *cl = ssi->cl;
967 
968 	ssip_xmit(cl);
969 }
970 
971 static netdev_tx_t ssip_pn_xmit(struct sk_buff *skb, struct net_device *dev)
972 {
973 	struct hsi_client *cl = to_hsi_client(dev->dev.parent);
974 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
975 	struct hsi_msg *msg;
976 
977 	if ((skb->protocol != htons(ETH_P_PHONET)) ||
978 					(skb->len < SSIP_MIN_PN_HDR))
979 		goto drop;
980 	/* Pad to 32-bits - FIXME: Revisit*/
981 	if ((skb->len & 3) && skb_pad(skb, 4 - (skb->len & 3)))
982 		goto inc_dropped;
983 
984 	/*
985 	 * Modem sends Phonet messages over SSI with its own endianness.
986 	 * Assume that modem has the same endianness as we do.
987 	 */
988 	if (skb_cow_head(skb, 0))
989 		goto drop;
990 
991 	/* length field is exchanged in network byte order */
992 	((u16 *)skb->data)[2] = htons(((u16 *)skb->data)[2]);
993 
994 	msg = ssip_alloc_data(ssi, skb, GFP_ATOMIC);
995 	if (!msg) {
996 		dev_dbg(&cl->device, "Dropping tx data: No memory\n");
997 		goto drop;
998 	}
999 	msg->complete = ssip_tx_data_complete;
1000 
1001 	spin_lock_bh(&ssi->lock);
1002 	if (unlikely(ssi->main_state != ACTIVE)) {
1003 		spin_unlock_bh(&ssi->lock);
1004 		dev_dbg(&cl->device, "Dropping tx data: CMT is OFFLINE\n");
1005 		goto drop2;
1006 	}
1007 	list_add_tail(&msg->link, &ssi->txqueue);
1008 	ssi->txqueue_len++;
1009 	if (dev->tx_queue_len < ssi->txqueue_len) {
1010 		dev_info(&cl->device, "TX queue full %d\n", ssi->txqueue_len);
1011 		netif_stop_queue(dev);
1012 	}
1013 	if (ssi->send_state == SEND_IDLE) {
1014 		ssip_set_txstate(ssi, WAIT4READY);
1015 		spin_unlock_bh(&ssi->lock);
1016 		dev_dbg(&cl->device, "Start TX qlen %d\n", ssi->txqueue_len);
1017 		hsi_start_tx(cl);
1018 	} else if (ssi->send_state == SEND_READY) {
1019 		/* Needed for cmt-speech workaround */
1020 		dev_dbg(&cl->device, "Start TX on SEND READY qlen %d\n",
1021 							ssi->txqueue_len);
1022 		spin_unlock_bh(&ssi->lock);
1023 		schedule_work(&ssi->work);
1024 	} else {
1025 		spin_unlock_bh(&ssi->lock);
1026 	}
1027 	dev->stats.tx_packets++;
1028 	dev->stats.tx_bytes += skb->len;
1029 
1030 	return NETDEV_TX_OK;
1031 drop2:
1032 	hsi_free_msg(msg);
1033 drop:
1034 	dev_kfree_skb(skb);
1035 inc_dropped:
1036 	dev->stats.tx_dropped++;
1037 
1038 	return NETDEV_TX_OK;
1039 }
1040 
1041 /* CMT reset event handler */
1042 void ssip_reset_event(struct hsi_client *master)
1043 {
1044 	struct ssi_protocol *ssi = hsi_client_drvdata(master);
1045 	dev_err(&ssi->cl->device, "CMT reset detected!\n");
1046 	ssip_error(ssi->cl);
1047 }
1048 EXPORT_SYMBOL_GPL(ssip_reset_event);
1049 
1050 static const struct net_device_ops ssip_pn_ops = {
1051 	.ndo_open	= ssip_pn_open,
1052 	.ndo_stop	= ssip_pn_stop,
1053 	.ndo_start_xmit	= ssip_pn_xmit,
1054 };
1055 
1056 static void ssip_pn_setup(struct net_device *dev)
1057 {
1058 	static const u8 addr = PN_MEDIA_SOS;
1059 
1060 	dev->features		= 0;
1061 	dev->netdev_ops		= &ssip_pn_ops;
1062 	dev->type		= ARPHRD_PHONET;
1063 	dev->flags		= IFF_POINTOPOINT | IFF_NOARP;
1064 	dev->mtu		= SSIP_DEFAULT_MTU;
1065 	dev->hard_header_len	= 1;
1066 	dev->addr_len		= 1;
1067 	dev_addr_set(dev, &addr);
1068 	dev->tx_queue_len	= SSIP_TXQUEUE_LEN;
1069 
1070 	dev->needs_free_netdev	= true;
1071 	dev->header_ops		= &phonet_header_ops;
1072 }
1073 
1074 static int ssi_protocol_probe(struct device *dev)
1075 {
1076 	static const char ifname[] = "phonet%d";
1077 	struct hsi_client *cl = to_hsi_client(dev);
1078 	struct ssi_protocol *ssi;
1079 	int err;
1080 
1081 	ssi = kzalloc(sizeof(*ssi), GFP_KERNEL);
1082 	if (!ssi)
1083 		return -ENOMEM;
1084 
1085 	spin_lock_init(&ssi->lock);
1086 	timer_setup(&ssi->rx_wd, ssip_rx_wd, TIMER_DEFERRABLE);
1087 	timer_setup(&ssi->tx_wd, ssip_tx_wd, TIMER_DEFERRABLE);
1088 	timer_setup(&ssi->keep_alive, ssip_keep_alive, 0);
1089 	INIT_LIST_HEAD(&ssi->txqueue);
1090 	INIT_LIST_HEAD(&ssi->cmdqueue);
1091 	atomic_set(&ssi->tx_usecnt, 0);
1092 	hsi_client_set_drvdata(cl, ssi);
1093 	ssi->cl = cl;
1094 	INIT_WORK(&ssi->work, ssip_xmit_work);
1095 
1096 	ssi->channel_id_cmd = hsi_get_channel_id_by_name(cl, "mcsaab-control");
1097 	if (ssi->channel_id_cmd < 0) {
1098 		err = ssi->channel_id_cmd;
1099 		dev_err(dev, "Could not get cmd channel (%d)\n", err);
1100 		goto out;
1101 	}
1102 
1103 	ssi->channel_id_data = hsi_get_channel_id_by_name(cl, "mcsaab-data");
1104 	if (ssi->channel_id_data < 0) {
1105 		err = ssi->channel_id_data;
1106 		dev_err(dev, "Could not get data channel (%d)\n", err);
1107 		goto out;
1108 	}
1109 
1110 	err = ssip_alloc_cmds(ssi);
1111 	if (err < 0) {
1112 		dev_err(dev, "No memory for commands\n");
1113 		goto out;
1114 	}
1115 
1116 	ssi->netdev = alloc_netdev(0, ifname, NET_NAME_UNKNOWN, ssip_pn_setup);
1117 	if (!ssi->netdev) {
1118 		dev_err(dev, "No memory for netdev\n");
1119 		err = -ENOMEM;
1120 		goto out1;
1121 	}
1122 
1123 	/* MTU range: 6 - 65535 */
1124 	ssi->netdev->min_mtu = PHONET_MIN_MTU;
1125 	ssi->netdev->max_mtu = SSIP_MAX_MTU;
1126 
1127 	SET_NETDEV_DEV(ssi->netdev, dev);
1128 	netif_carrier_off(ssi->netdev);
1129 	err = register_netdev(ssi->netdev);
1130 	if (err < 0) {
1131 		dev_err(dev, "Register netdev failed (%d)\n", err);
1132 		goto out2;
1133 	}
1134 
1135 	list_add(&ssi->link, &ssip_list);
1136 
1137 	dev_dbg(dev, "channel configuration: cmd=%d, data=%d\n",
1138 		ssi->channel_id_cmd, ssi->channel_id_data);
1139 
1140 	return 0;
1141 out2:
1142 	free_netdev(ssi->netdev);
1143 out1:
1144 	ssip_free_cmds(ssi);
1145 out:
1146 	kfree(ssi);
1147 
1148 	return err;
1149 }
1150 
1151 static int ssi_protocol_remove(struct device *dev)
1152 {
1153 	struct hsi_client *cl = to_hsi_client(dev);
1154 	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
1155 
1156 	list_del(&ssi->link);
1157 	unregister_netdev(ssi->netdev);
1158 	ssip_free_cmds(ssi);
1159 	hsi_client_set_drvdata(cl, NULL);
1160 	kfree(ssi);
1161 
1162 	return 0;
1163 }
1164 
1165 static struct hsi_client_driver ssip_driver = {
1166 	.driver = {
1167 		.name	= "ssi-protocol",
1168 		.owner	= THIS_MODULE,
1169 		.probe	= ssi_protocol_probe,
1170 		.remove	= ssi_protocol_remove,
1171 	},
1172 };
1173 
1174 static int __init ssip_init(void)
1175 {
1176 	pr_info("SSI protocol aka McSAAB added\n");
1177 
1178 	return hsi_register_client_driver(&ssip_driver);
1179 }
1180 module_init(ssip_init);
1181 
1182 static void __exit ssip_exit(void)
1183 {
1184 	hsi_unregister_client_driver(&ssip_driver);
1185 	pr_info("SSI protocol driver removed\n");
1186 }
1187 module_exit(ssip_exit);
1188 
1189 MODULE_ALIAS("hsi:ssi-protocol");
1190 MODULE_AUTHOR("Carlos Chinea <carlos.chinea@nokia.com>");
1191 MODULE_AUTHOR("Remi Denis-Courmont <remi.denis-courmont@nokia.com>");
1192 MODULE_DESCRIPTION("SSI protocol improved aka McSAAB");
1193 MODULE_LICENSE("GPL");
1194