xref: /openbmc/linux/drivers/net/caif/caif_virtio.c (revision 11a37eb6)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) ST-Ericsson AB 2013
4  * Authors: Vicram Arv
5  *	    Dmitry Tarnyagin <dmitry.tarnyagin@lockless.no>
6  *	    Sjur Brendeland
7  */
8 #include <linux/module.h>
9 #include <linux/if_arp.h>
10 #include <linux/virtio.h>
11 #include <linux/vringh.h>
12 #include <linux/debugfs.h>
13 #include <linux/spinlock.h>
14 #include <linux/genalloc.h>
15 #include <linux/interrupt.h>
16 #include <linux/netdevice.h>
17 #include <linux/rtnetlink.h>
18 #include <linux/virtio_ids.h>
19 #include <linux/virtio_caif.h>
20 #include <linux/virtio_ring.h>
21 #include <linux/dma-mapping.h>
22 #include <net/caif/caif_dev.h>
23 #include <linux/virtio_config.h>
24 
25 MODULE_LICENSE("GPL v2");
26 MODULE_AUTHOR("Vicram Arv");
27 MODULE_AUTHOR("Sjur Brendeland");
28 MODULE_DESCRIPTION("Virtio CAIF Driver");
29 
30 /* NAPI schedule quota */
31 #define CFV_DEFAULT_QUOTA 32
32 
33 /* Defaults used if virtio config space is unavailable */
34 #define CFV_DEF_MTU_SIZE 4096
35 #define CFV_DEF_HEADROOM 32
36 #define CFV_DEF_TAILROOM 32
37 
38 /* Required IP header alignment */
39 #define IP_HDR_ALIGN 4
40 
41 /* struct cfv_napi_contxt - NAPI context info
42  * @riov: IOV holding data read from the ring. Note that riov may
43  *	  still hold data when cfv_rx_poll() returns.
44  * @head: Last descriptor ID we received from vringh_getdesc_kern.
45  *	  We use this to put descriptor back on the used ring. USHRT_MAX is
46  *	  used to indicate invalid head-id.
47  */
48 struct cfv_napi_context {
49 	struct vringh_kiov riov;
50 	unsigned short head;
51 };
52 
53 /* struct cfv_stats - statistics for debugfs
54  * @rx_napi_complete:	Number of NAPI completions (RX)
55  * @rx_napi_resched:	Number of calls where the full quota was used (RX)
56  * @rx_nomem:		Number of SKB alloc failures (RX)
57  * @rx_kicks:		Number of RX kicks
58  * @tx_full_ring:	Number times TX ring was full
59  * @tx_no_mem:		Number of times TX went out of memory
60  * @tx_flow_on:		Number of flow on (TX)
61  * @tx_kicks:		Number of TX kicks
62  */
63 struct cfv_stats {
64 	u32 rx_napi_complete;
65 	u32 rx_napi_resched;
66 	u32 rx_nomem;
67 	u32 rx_kicks;
68 	u32 tx_full_ring;
69 	u32 tx_no_mem;
70 	u32 tx_flow_on;
71 	u32 tx_kicks;
72 };
73 
74 /* struct cfv_info - Caif Virtio control structure
75  * @cfdev:	caif common header
76  * @vdev:	Associated virtio device
77  * @vr_rx:	rx/downlink host vring
78  * @vq_tx:	tx/uplink virtqueue
79  * @ndev:	CAIF link layer device
80  * @watermark_tx: indicates number of free descriptors we need
81  *		to reopen the tx-queues after overload.
82  * @tx_lock:	protects vq_tx from concurrent use
83  * @tx_release_tasklet: Tasklet for freeing consumed TX buffers
84  * @napi:       Napi context used in cfv_rx_poll()
85  * @ctx:        Context data used in cfv_rx_poll()
86  * @tx_hr:	transmit headroom
87  * @rx_hr:	receive headroom
88  * @tx_tr:	transmit tail room
89  * @rx_tr:	receive tail room
90  * @mtu:	transmit max size
91  * @mru:	receive max size
92  * @allocsz:    size of dma memory reserved for TX buffers
93  * @alloc_addr: virtual address to dma memory for TX buffers
94  * @alloc_dma:  dma address to dma memory for TX buffers
95  * @genpool:    Gen Pool used for allocating TX buffers
96  * @reserved_mem: Pointer to memory reserve allocated from genpool
97  * @reserved_size: Size of memory reserve allocated from genpool
98  * @stats:       Statistics exposed in sysfs
99  * @debugfs:    Debugfs dentry for statistic counters
100  */
101 struct cfv_info {
102 	struct caif_dev_common cfdev;
103 	struct virtio_device *vdev;
104 	struct vringh *vr_rx;
105 	struct virtqueue *vq_tx;
106 	struct net_device *ndev;
107 	unsigned int watermark_tx;
108 	/* Protect access to vq_tx */
109 	spinlock_t tx_lock;
110 	struct tasklet_struct tx_release_tasklet;
111 	struct napi_struct napi;
112 	struct cfv_napi_context ctx;
113 	u16 tx_hr;
114 	u16 rx_hr;
115 	u16 tx_tr;
116 	u16 rx_tr;
117 	u32 mtu;
118 	u32 mru;
119 	size_t allocsz;
120 	void *alloc_addr;
121 	dma_addr_t alloc_dma;
122 	struct gen_pool *genpool;
123 	unsigned long reserved_mem;
124 	size_t reserved_size;
125 	struct cfv_stats stats;
126 	struct dentry *debugfs;
127 };
128 
129 /* struct buf_info - maintains transmit buffer data handle
130  * @size:	size of transmit buffer
131  * @dma_handle: handle to allocated dma device memory area
132  * @vaddr:	virtual address mapping to allocated memory area
133  */
134 struct buf_info {
135 	size_t size;
136 	u8 *vaddr;
137 };
138 
139 /* Called from virtio device, in IRQ context */
cfv_release_cb(struct virtqueue * vq_tx)140 static void cfv_release_cb(struct virtqueue *vq_tx)
141 {
142 	struct cfv_info *cfv = vq_tx->vdev->priv;
143 
144 	++cfv->stats.tx_kicks;
145 	tasklet_schedule(&cfv->tx_release_tasklet);
146 }
147 
free_buf_info(struct cfv_info * cfv,struct buf_info * buf_info)148 static void free_buf_info(struct cfv_info *cfv, struct buf_info *buf_info)
149 {
150 	if (!buf_info)
151 		return;
152 	gen_pool_free(cfv->genpool, (unsigned long) buf_info->vaddr,
153 		      buf_info->size);
154 	kfree(buf_info);
155 }
156 
157 /* This is invoked whenever the remote processor completed processing
158  * a TX msg we just sent, and the buffer is put back to the used ring.
159  */
cfv_release_used_buf(struct virtqueue * vq_tx)160 static void cfv_release_used_buf(struct virtqueue *vq_tx)
161 {
162 	struct cfv_info *cfv = vq_tx->vdev->priv;
163 	unsigned long flags;
164 
165 	BUG_ON(vq_tx != cfv->vq_tx);
166 
167 	for (;;) {
168 		unsigned int len;
169 		struct buf_info *buf_info;
170 
171 		/* Get used buffer from used ring to recycle used descriptors */
172 		spin_lock_irqsave(&cfv->tx_lock, flags);
173 		buf_info = virtqueue_get_buf(vq_tx, &len);
174 		spin_unlock_irqrestore(&cfv->tx_lock, flags);
175 
176 		/* Stop looping if there are no more buffers to free */
177 		if (!buf_info)
178 			break;
179 
180 		free_buf_info(cfv, buf_info);
181 
182 		/* watermark_tx indicates if we previously stopped the tx
183 		 * queues. If we have enough free stots in the virtio ring,
184 		 * re-establish memory reserved and open up tx queues.
185 		 */
186 		if (cfv->vq_tx->num_free <= cfv->watermark_tx)
187 			continue;
188 
189 		/* Re-establish memory reserve */
190 		if (cfv->reserved_mem == 0 && cfv->genpool)
191 			cfv->reserved_mem =
192 				gen_pool_alloc(cfv->genpool,
193 					       cfv->reserved_size);
194 
195 		/* Open up the tx queues */
196 		if (cfv->reserved_mem) {
197 			cfv->watermark_tx =
198 				virtqueue_get_vring_size(cfv->vq_tx);
199 			netif_tx_wake_all_queues(cfv->ndev);
200 			/* Buffers are recycled in cfv_netdev_tx, so
201 			 * disable notifications when queues are opened.
202 			 */
203 			virtqueue_disable_cb(cfv->vq_tx);
204 			++cfv->stats.tx_flow_on;
205 		} else {
206 			/* if no memory reserve, wait for more free slots */
207 			WARN_ON(cfv->watermark_tx >
208 			       virtqueue_get_vring_size(cfv->vq_tx));
209 			cfv->watermark_tx +=
210 				virtqueue_get_vring_size(cfv->vq_tx) / 4;
211 		}
212 	}
213 }
214 
215 /* Allocate a SKB and copy packet data to it */
cfv_alloc_and_copy_skb(int * err,struct cfv_info * cfv,u8 * frm,u32 frm_len)216 static struct sk_buff *cfv_alloc_and_copy_skb(int *err,
217 					      struct cfv_info *cfv,
218 					      u8 *frm, u32 frm_len)
219 {
220 	struct sk_buff *skb;
221 	u32 cfpkt_len, pad_len;
222 
223 	*err = 0;
224 	/* Verify that packet size with down-link header and mtu size */
225 	if (frm_len > cfv->mru || frm_len <= cfv->rx_hr + cfv->rx_tr) {
226 		netdev_err(cfv->ndev,
227 			   "Invalid frmlen:%u  mtu:%u hr:%d tr:%d\n",
228 			   frm_len, cfv->mru,  cfv->rx_hr,
229 			   cfv->rx_tr);
230 		*err = -EPROTO;
231 		return NULL;
232 	}
233 
234 	cfpkt_len = frm_len - (cfv->rx_hr + cfv->rx_tr);
235 	pad_len = (unsigned long)(frm + cfv->rx_hr) & (IP_HDR_ALIGN - 1);
236 
237 	skb = netdev_alloc_skb(cfv->ndev, frm_len + pad_len);
238 	if (!skb) {
239 		*err = -ENOMEM;
240 		return NULL;
241 	}
242 
243 	skb_reserve(skb, cfv->rx_hr + pad_len);
244 
245 	skb_put_data(skb, frm + cfv->rx_hr, cfpkt_len);
246 	return skb;
247 }
248 
249 /* Get packets from the host vring */
cfv_rx_poll(struct napi_struct * napi,int quota)250 static int cfv_rx_poll(struct napi_struct *napi, int quota)
251 {
252 	struct cfv_info *cfv = container_of(napi, struct cfv_info, napi);
253 	int rxcnt = 0;
254 	int err = 0;
255 	void *buf;
256 	struct sk_buff *skb;
257 	struct vringh_kiov *riov = &cfv->ctx.riov;
258 	unsigned int skb_len;
259 
260 	do {
261 		skb = NULL;
262 
263 		/* Put the previous iovec back on the used ring and
264 		 * fetch a new iovec if we have processed all elements.
265 		 */
266 		if (riov->i == riov->used) {
267 			if (cfv->ctx.head != USHRT_MAX) {
268 				vringh_complete_kern(cfv->vr_rx,
269 						     cfv->ctx.head,
270 						     0);
271 				cfv->ctx.head = USHRT_MAX;
272 			}
273 
274 			err = vringh_getdesc_kern(
275 				cfv->vr_rx,
276 				riov,
277 				NULL,
278 				&cfv->ctx.head,
279 				GFP_ATOMIC);
280 
281 			if (err <= 0)
282 				goto exit;
283 		}
284 
285 		buf = phys_to_virt((unsigned long) riov->iov[riov->i].iov_base);
286 		/* TODO: Add check on valid buffer address */
287 
288 		skb = cfv_alloc_and_copy_skb(&err, cfv, buf,
289 					     riov->iov[riov->i].iov_len);
290 		if (unlikely(err))
291 			goto exit;
292 
293 		/* Push received packet up the stack. */
294 		skb_len = skb->len;
295 		skb->protocol = htons(ETH_P_CAIF);
296 		skb_reset_mac_header(skb);
297 		skb->dev = cfv->ndev;
298 		err = netif_receive_skb(skb);
299 		if (unlikely(err)) {
300 			++cfv->ndev->stats.rx_dropped;
301 		} else {
302 			++cfv->ndev->stats.rx_packets;
303 			cfv->ndev->stats.rx_bytes += skb_len;
304 		}
305 
306 		++riov->i;
307 		++rxcnt;
308 	} while (rxcnt < quota);
309 
310 	++cfv->stats.rx_napi_resched;
311 	goto out;
312 
313 exit:
314 	switch (err) {
315 	case 0:
316 		++cfv->stats.rx_napi_complete;
317 
318 		/* Really out of packets? (stolen from virtio_net)*/
319 		napi_complete(napi);
320 		if (unlikely(!vringh_notify_enable_kern(cfv->vr_rx)) &&
321 		    napi_schedule_prep(napi)) {
322 			vringh_notify_disable_kern(cfv->vr_rx);
323 			__napi_schedule(napi);
324 		}
325 		break;
326 
327 	case -ENOMEM:
328 		++cfv->stats.rx_nomem;
329 		dev_kfree_skb(skb);
330 		/* Stop NAPI poll on OOM, we hope to be polled later */
331 		napi_complete(napi);
332 		vringh_notify_enable_kern(cfv->vr_rx);
333 		break;
334 
335 	default:
336 		/* We're doomed, any modem fault is fatal */
337 		netdev_warn(cfv->ndev, "Bad ring, disable device\n");
338 		cfv->ndev->stats.rx_dropped = riov->used - riov->i;
339 		napi_complete(napi);
340 		vringh_notify_disable_kern(cfv->vr_rx);
341 		netif_carrier_off(cfv->ndev);
342 		break;
343 	}
344 out:
345 	if (rxcnt && vringh_need_notify_kern(cfv->vr_rx) > 0)
346 		vringh_notify(cfv->vr_rx);
347 	return rxcnt;
348 }
349 
cfv_recv(struct virtio_device * vdev,struct vringh * vr_rx)350 static void cfv_recv(struct virtio_device *vdev, struct vringh *vr_rx)
351 {
352 	struct cfv_info *cfv = vdev->priv;
353 
354 	++cfv->stats.rx_kicks;
355 	vringh_notify_disable_kern(cfv->vr_rx);
356 	napi_schedule(&cfv->napi);
357 }
358 
cfv_destroy_genpool(struct cfv_info * cfv)359 static void cfv_destroy_genpool(struct cfv_info *cfv)
360 {
361 	if (cfv->alloc_addr)
362 		dma_free_coherent(cfv->vdev->dev.parent->parent,
363 				  cfv->allocsz, cfv->alloc_addr,
364 				  cfv->alloc_dma);
365 
366 	if (!cfv->genpool)
367 		return;
368 	gen_pool_free(cfv->genpool,  cfv->reserved_mem,
369 		      cfv->reserved_size);
370 	gen_pool_destroy(cfv->genpool);
371 	cfv->genpool = NULL;
372 }
373 
cfv_create_genpool(struct cfv_info * cfv)374 static int cfv_create_genpool(struct cfv_info *cfv)
375 {
376 	int err;
377 
378 	/* dma_alloc can only allocate whole pages, and we need a more
379 	 * fine graned allocation so we use genpool. We ask for space needed
380 	 * by IP and a full ring. If the dma allcoation fails we retry with a
381 	 * smaller allocation size.
382 	 */
383 	err = -ENOMEM;
384 	cfv->allocsz = (virtqueue_get_vring_size(cfv->vq_tx) *
385 			(ETH_DATA_LEN + cfv->tx_hr + cfv->tx_tr) * 11)/10;
386 	if (cfv->allocsz <= (num_possible_cpus() + 1) * cfv->ndev->mtu)
387 		return -EINVAL;
388 
389 	for (;;) {
390 		if (cfv->allocsz <= num_possible_cpus() * cfv->ndev->mtu) {
391 			netdev_info(cfv->ndev, "Not enough device memory\n");
392 			return -ENOMEM;
393 		}
394 
395 		cfv->alloc_addr = dma_alloc_coherent(
396 						cfv->vdev->dev.parent->parent,
397 						cfv->allocsz, &cfv->alloc_dma,
398 						GFP_ATOMIC);
399 		if (cfv->alloc_addr)
400 			break;
401 
402 		cfv->allocsz = (cfv->allocsz * 3) >> 2;
403 	}
404 
405 	netdev_dbg(cfv->ndev, "Allocated %zd bytes from dma-memory\n",
406 		   cfv->allocsz);
407 
408 	/* Allocate on 128 bytes boundaries (1 << 7)*/
409 	cfv->genpool = gen_pool_create(7, -1);
410 	if (!cfv->genpool)
411 		goto err;
412 
413 	err = gen_pool_add_virt(cfv->genpool, (unsigned long)cfv->alloc_addr,
414 				(phys_addr_t)virt_to_phys(cfv->alloc_addr),
415 				cfv->allocsz, -1);
416 	if (err)
417 		goto err;
418 
419 	/* Reserve some memory for low memory situations. If we hit the roof
420 	 * in the memory pool, we stop TX flow and release the reserve.
421 	 */
422 	cfv->reserved_size = num_possible_cpus() * cfv->ndev->mtu;
423 	cfv->reserved_mem = gen_pool_alloc(cfv->genpool,
424 					   cfv->reserved_size);
425 	if (!cfv->reserved_mem) {
426 		err = -ENOMEM;
427 		goto err;
428 	}
429 
430 	cfv->watermark_tx = virtqueue_get_vring_size(cfv->vq_tx);
431 	return 0;
432 err:
433 	cfv_destroy_genpool(cfv);
434 	return err;
435 }
436 
437 /* Enable the CAIF interface and allocate the memory-pool */
cfv_netdev_open(struct net_device * netdev)438 static int cfv_netdev_open(struct net_device *netdev)
439 {
440 	struct cfv_info *cfv = netdev_priv(netdev);
441 
442 	if (cfv_create_genpool(cfv))
443 		return -ENOMEM;
444 
445 	netif_carrier_on(netdev);
446 	napi_enable(&cfv->napi);
447 
448 	/* Schedule NAPI to read any pending packets */
449 	napi_schedule(&cfv->napi);
450 	return 0;
451 }
452 
453 /* Disable the CAIF interface and free the memory-pool */
cfv_netdev_close(struct net_device * netdev)454 static int cfv_netdev_close(struct net_device *netdev)
455 {
456 	struct cfv_info *cfv = netdev_priv(netdev);
457 	unsigned long flags;
458 	struct buf_info *buf_info;
459 
460 	/* Disable interrupts, queues and NAPI polling */
461 	netif_carrier_off(netdev);
462 	virtqueue_disable_cb(cfv->vq_tx);
463 	vringh_notify_disable_kern(cfv->vr_rx);
464 	napi_disable(&cfv->napi);
465 
466 	/* Release any TX buffers on both used and available rings */
467 	cfv_release_used_buf(cfv->vq_tx);
468 	spin_lock_irqsave(&cfv->tx_lock, flags);
469 	while ((buf_info = virtqueue_detach_unused_buf(cfv->vq_tx)))
470 		free_buf_info(cfv, buf_info);
471 	spin_unlock_irqrestore(&cfv->tx_lock, flags);
472 
473 	/* Release all dma allocated memory and destroy the pool */
474 	cfv_destroy_genpool(cfv);
475 	return 0;
476 }
477 
478 /* Allocate a buffer in dma-memory and copy skb to it */
cfv_alloc_and_copy_to_shm(struct cfv_info * cfv,struct sk_buff * skb,struct scatterlist * sg)479 static struct buf_info *cfv_alloc_and_copy_to_shm(struct cfv_info *cfv,
480 						       struct sk_buff *skb,
481 						       struct scatterlist *sg)
482 {
483 	struct caif_payload_info *info = (void *)&skb->cb;
484 	struct buf_info *buf_info = NULL;
485 	u8 pad_len, hdr_ofs;
486 
487 	if (!cfv->genpool)
488 		goto err;
489 
490 	if (unlikely(cfv->tx_hr + skb->len + cfv->tx_tr > cfv->mtu)) {
491 		netdev_warn(cfv->ndev, "Invalid packet len (%d > %d)\n",
492 			    cfv->tx_hr + skb->len + cfv->tx_tr, cfv->mtu);
493 		goto err;
494 	}
495 
496 	buf_info = kmalloc(sizeof(struct buf_info), GFP_ATOMIC);
497 	if (unlikely(!buf_info))
498 		goto err;
499 
500 	/* Make the IP header aligned in the buffer */
501 	hdr_ofs = cfv->tx_hr + info->hdr_len;
502 	pad_len = hdr_ofs & (IP_HDR_ALIGN - 1);
503 	buf_info->size = cfv->tx_hr + skb->len + cfv->tx_tr + pad_len;
504 
505 	/* allocate dma memory buffer */
506 	buf_info->vaddr = (void *)gen_pool_alloc(cfv->genpool, buf_info->size);
507 	if (unlikely(!buf_info->vaddr))
508 		goto err;
509 
510 	/* copy skbuf contents to send buffer */
511 	skb_copy_bits(skb, 0, buf_info->vaddr + cfv->tx_hr + pad_len, skb->len);
512 	sg_init_one(sg, buf_info->vaddr + pad_len,
513 		    skb->len + cfv->tx_hr + cfv->rx_hr);
514 
515 	return buf_info;
516 err:
517 	kfree(buf_info);
518 	return NULL;
519 }
520 
521 /* Put the CAIF packet on the virtio ring and kick the receiver */
cfv_netdev_tx(struct sk_buff * skb,struct net_device * netdev)522 static netdev_tx_t cfv_netdev_tx(struct sk_buff *skb, struct net_device *netdev)
523 {
524 	struct cfv_info *cfv = netdev_priv(netdev);
525 	struct buf_info *buf_info;
526 	struct scatterlist sg;
527 	unsigned long flags;
528 	bool flow_off = false;
529 	int ret;
530 
531 	/* garbage collect released buffers */
532 	cfv_release_used_buf(cfv->vq_tx);
533 	spin_lock_irqsave(&cfv->tx_lock, flags);
534 
535 	/* Flow-off check takes into account number of cpus to make sure
536 	 * virtqueue will not be overfilled in any possible smp conditions.
537 	 *
538 	 * Flow-on is triggered when sufficient buffers are freed
539 	 */
540 	if (unlikely(cfv->vq_tx->num_free <= num_present_cpus())) {
541 		flow_off = true;
542 		cfv->stats.tx_full_ring++;
543 	}
544 
545 	/* If we run out of memory, we release the memory reserve and retry
546 	 * allocation.
547 	 */
548 	buf_info = cfv_alloc_and_copy_to_shm(cfv, skb, &sg);
549 	if (unlikely(!buf_info)) {
550 		cfv->stats.tx_no_mem++;
551 		flow_off = true;
552 
553 		if (cfv->reserved_mem && cfv->genpool) {
554 			gen_pool_free(cfv->genpool,  cfv->reserved_mem,
555 				      cfv->reserved_size);
556 			cfv->reserved_mem = 0;
557 			buf_info = cfv_alloc_and_copy_to_shm(cfv, skb, &sg);
558 		}
559 	}
560 
561 	if (unlikely(flow_off)) {
562 		/* Turn flow on when a 1/4 of the descriptors are released */
563 		cfv->watermark_tx = virtqueue_get_vring_size(cfv->vq_tx) / 4;
564 		/* Enable notifications of recycled TX buffers */
565 		virtqueue_enable_cb(cfv->vq_tx);
566 		netif_tx_stop_all_queues(netdev);
567 	}
568 
569 	if (unlikely(!buf_info)) {
570 		/* If the memory reserve does it's job, this shouldn't happen */
571 		netdev_warn(cfv->ndev, "Out of gen_pool memory\n");
572 		goto err;
573 	}
574 
575 	ret = virtqueue_add_outbuf(cfv->vq_tx, &sg, 1, buf_info, GFP_ATOMIC);
576 	if (unlikely((ret < 0))) {
577 		/* If flow control works, this shouldn't happen */
578 		netdev_warn(cfv->ndev, "Failed adding buffer to TX vring:%d\n",
579 			    ret);
580 		goto err;
581 	}
582 
583 	/* update netdev statistics */
584 	cfv->ndev->stats.tx_packets++;
585 	cfv->ndev->stats.tx_bytes += skb->len;
586 	spin_unlock_irqrestore(&cfv->tx_lock, flags);
587 
588 	/* tell the remote processor it has a pending message to read */
589 	virtqueue_kick(cfv->vq_tx);
590 
591 	dev_kfree_skb(skb);
592 	return NETDEV_TX_OK;
593 err:
594 	spin_unlock_irqrestore(&cfv->tx_lock, flags);
595 	cfv->ndev->stats.tx_dropped++;
596 	free_buf_info(cfv, buf_info);
597 	dev_kfree_skb(skb);
598 	return NETDEV_TX_OK;
599 }
600 
cfv_tx_release_tasklet(struct tasklet_struct * t)601 static void cfv_tx_release_tasklet(struct tasklet_struct *t)
602 {
603 	struct cfv_info *cfv = from_tasklet(cfv, t, tx_release_tasklet);
604 	cfv_release_used_buf(cfv->vq_tx);
605 }
606 
607 static const struct net_device_ops cfv_netdev_ops = {
608 	.ndo_open = cfv_netdev_open,
609 	.ndo_stop = cfv_netdev_close,
610 	.ndo_start_xmit = cfv_netdev_tx,
611 };
612 
cfv_netdev_setup(struct net_device * netdev)613 static void cfv_netdev_setup(struct net_device *netdev)
614 {
615 	netdev->netdev_ops = &cfv_netdev_ops;
616 	netdev->type = ARPHRD_CAIF;
617 	netdev->tx_queue_len = 100;
618 	netdev->flags = IFF_POINTOPOINT | IFF_NOARP;
619 	netdev->mtu = CFV_DEF_MTU_SIZE;
620 	netdev->needs_free_netdev = true;
621 }
622 
623 /* Create debugfs counters for the device */
debugfs_init(struct cfv_info * cfv)624 static inline void debugfs_init(struct cfv_info *cfv)
625 {
626 	cfv->debugfs = debugfs_create_dir(netdev_name(cfv->ndev), NULL);
627 
628 	debugfs_create_u32("rx-napi-complete", 0400, cfv->debugfs,
629 			   &cfv->stats.rx_napi_complete);
630 	debugfs_create_u32("rx-napi-resched", 0400, cfv->debugfs,
631 			   &cfv->stats.rx_napi_resched);
632 	debugfs_create_u32("rx-nomem", 0400, cfv->debugfs,
633 			   &cfv->stats.rx_nomem);
634 	debugfs_create_u32("rx-kicks", 0400, cfv->debugfs,
635 			   &cfv->stats.rx_kicks);
636 	debugfs_create_u32("tx-full-ring", 0400, cfv->debugfs,
637 			   &cfv->stats.tx_full_ring);
638 	debugfs_create_u32("tx-no-mem", 0400, cfv->debugfs,
639 			   &cfv->stats.tx_no_mem);
640 	debugfs_create_u32("tx-kicks", 0400, cfv->debugfs,
641 			   &cfv->stats.tx_kicks);
642 	debugfs_create_u32("tx-flow-on", 0400, cfv->debugfs,
643 			   &cfv->stats.tx_flow_on);
644 }
645 
646 /* Setup CAIF for the a virtio device */
cfv_probe(struct virtio_device * vdev)647 static int cfv_probe(struct virtio_device *vdev)
648 {
649 	vq_callback_t *vq_cbs = cfv_release_cb;
650 	vrh_callback_t *vrh_cbs = cfv_recv;
651 	const char *names =  "output";
652 	const char *cfv_netdev_name = "cfvrt";
653 	struct net_device *netdev;
654 	struct cfv_info *cfv;
655 	int err;
656 
657 	netdev = alloc_netdev(sizeof(struct cfv_info), cfv_netdev_name,
658 			      NET_NAME_UNKNOWN, cfv_netdev_setup);
659 	if (!netdev)
660 		return -ENOMEM;
661 
662 	cfv = netdev_priv(netdev);
663 	cfv->vdev = vdev;
664 	cfv->ndev = netdev;
665 
666 	spin_lock_init(&cfv->tx_lock);
667 
668 	/* Get the RX virtio ring. This is a "host side vring". */
669 	err = -ENODEV;
670 	if (!vdev->vringh_config || !vdev->vringh_config->find_vrhs)
671 		goto err;
672 
673 	err = vdev->vringh_config->find_vrhs(vdev, 1, &cfv->vr_rx, &vrh_cbs);
674 	if (err)
675 		goto err;
676 
677 	/* Get the TX virtio ring. This is a "guest side vring". */
678 	err = virtio_find_vqs(vdev, 1, &cfv->vq_tx, &vq_cbs, &names, NULL);
679 	if (err)
680 		goto err;
681 
682 	/* Get the CAIF configuration from virtio config space, if available */
683 	if (vdev->config->get) {
684 		virtio_cread(vdev, struct virtio_caif_transf_config, headroom,
685 			     &cfv->tx_hr);
686 		virtio_cread(vdev, struct virtio_caif_transf_config, headroom,
687 			     &cfv->rx_hr);
688 		virtio_cread(vdev, struct virtio_caif_transf_config, tailroom,
689 			     &cfv->tx_tr);
690 		virtio_cread(vdev, struct virtio_caif_transf_config, tailroom,
691 			     &cfv->rx_tr);
692 		virtio_cread(vdev, struct virtio_caif_transf_config, mtu,
693 			     &cfv->mtu);
694 		virtio_cread(vdev, struct virtio_caif_transf_config, mtu,
695 			     &cfv->mru);
696 	} else {
697 		cfv->tx_hr = CFV_DEF_HEADROOM;
698 		cfv->rx_hr = CFV_DEF_HEADROOM;
699 		cfv->tx_tr = CFV_DEF_TAILROOM;
700 		cfv->rx_tr = CFV_DEF_TAILROOM;
701 		cfv->mtu = CFV_DEF_MTU_SIZE;
702 		cfv->mru = CFV_DEF_MTU_SIZE;
703 	}
704 
705 	netdev->needed_headroom = cfv->tx_hr;
706 	netdev->needed_tailroom = cfv->tx_tr;
707 
708 	/* Disable buffer release interrupts unless we have stopped TX queues */
709 	virtqueue_disable_cb(cfv->vq_tx);
710 
711 	netdev->mtu = cfv->mtu - cfv->tx_tr;
712 	vdev->priv = cfv;
713 
714 	/* Initialize NAPI poll context data */
715 	vringh_kiov_init(&cfv->ctx.riov, NULL, 0);
716 	cfv->ctx.head = USHRT_MAX;
717 	netif_napi_add_weight(netdev, &cfv->napi, cfv_rx_poll,
718 			      CFV_DEFAULT_QUOTA);
719 
720 	tasklet_setup(&cfv->tx_release_tasklet, cfv_tx_release_tasklet);
721 
722 	/* Carrier is off until netdevice is opened */
723 	netif_carrier_off(netdev);
724 
725 	/* serialize netdev register + virtio_device_ready() with ndo_open() */
726 	rtnl_lock();
727 
728 	/* register Netdev */
729 	err = register_netdevice(netdev);
730 	if (err) {
731 		rtnl_unlock();
732 		dev_err(&vdev->dev, "Unable to register netdev (%d)\n", err);
733 		goto err;
734 	}
735 
736 	virtio_device_ready(vdev);
737 
738 	rtnl_unlock();
739 
740 	debugfs_init(cfv);
741 
742 	return 0;
743 err:
744 	netdev_warn(cfv->ndev, "CAIF Virtio probe failed:%d\n", err);
745 
746 	if (cfv->vr_rx)
747 		vdev->vringh_config->del_vrhs(cfv->vdev);
748 	if (cfv->vdev)
749 		vdev->config->del_vqs(cfv->vdev);
750 	free_netdev(netdev);
751 	return err;
752 }
753 
cfv_remove(struct virtio_device * vdev)754 static void cfv_remove(struct virtio_device *vdev)
755 {
756 	struct cfv_info *cfv = vdev->priv;
757 
758 	rtnl_lock();
759 	dev_close(cfv->ndev);
760 	rtnl_unlock();
761 
762 	tasklet_kill(&cfv->tx_release_tasklet);
763 	debugfs_remove_recursive(cfv->debugfs);
764 
765 	vringh_kiov_cleanup(&cfv->ctx.riov);
766 	virtio_reset_device(vdev);
767 	vdev->vringh_config->del_vrhs(cfv->vdev);
768 	cfv->vr_rx = NULL;
769 	vdev->config->del_vqs(cfv->vdev);
770 	unregister_netdev(cfv->ndev);
771 }
772 
773 static struct virtio_device_id id_table[] = {
774 	{ VIRTIO_ID_CAIF, VIRTIO_DEV_ANY_ID },
775 	{ 0 },
776 };
777 
778 static unsigned int features[] = {
779 };
780 
781 static struct virtio_driver caif_virtio_driver = {
782 	.feature_table		= features,
783 	.feature_table_size	= ARRAY_SIZE(features),
784 	.driver.name		= KBUILD_MODNAME,
785 	.driver.owner		= THIS_MODULE,
786 	.id_table		= id_table,
787 	.probe			= cfv_probe,
788 	.remove			= cfv_remove,
789 };
790 
791 module_virtio_driver(caif_virtio_driver);
792 MODULE_DEVICE_TABLE(virtio, id_table);
793