1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* MHI Network driver - Network over MHI bus
3 *
4 * Copyright (C) 2020 Linaro Ltd <loic.poulain@linaro.org>
5 */
6
7 #include <linux/if_arp.h>
8 #include <linux/mhi.h>
9 #include <linux/mod_devicetable.h>
10 #include <linux/module.h>
11 #include <linux/netdevice.h>
12 #include <linux/skbuff.h>
13 #include <linux/u64_stats_sync.h>
14
15 #define MHI_NET_MIN_MTU ETH_MIN_MTU
16 #define MHI_NET_MAX_MTU 0xffff
17 #define MHI_NET_DEFAULT_MTU 0x4000
18
19 struct mhi_net_stats {
20 u64_stats_t rx_packets;
21 u64_stats_t rx_bytes;
22 u64_stats_t rx_errors;
23 u64_stats_t tx_packets;
24 u64_stats_t tx_bytes;
25 u64_stats_t tx_errors;
26 u64_stats_t tx_dropped;
27 struct u64_stats_sync tx_syncp;
28 struct u64_stats_sync rx_syncp;
29 };
30
31 struct mhi_net_dev {
32 struct mhi_device *mdev;
33 struct net_device *ndev;
34 struct sk_buff *skbagg_head;
35 struct sk_buff *skbagg_tail;
36 struct delayed_work rx_refill;
37 struct mhi_net_stats stats;
38 u32 rx_queue_sz;
39 int msg_enable;
40 unsigned int mru;
41 };
42
43 struct mhi_device_info {
44 const char *netname;
45 };
46
mhi_ndo_open(struct net_device * ndev)47 static int mhi_ndo_open(struct net_device *ndev)
48 {
49 struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
50
51 /* Feed the rx buffer pool */
52 schedule_delayed_work(&mhi_netdev->rx_refill, 0);
53
54 /* Carrier is established via out-of-band channel (e.g. qmi) */
55 netif_carrier_on(ndev);
56
57 netif_start_queue(ndev);
58
59 return 0;
60 }
61
mhi_ndo_stop(struct net_device * ndev)62 static int mhi_ndo_stop(struct net_device *ndev)
63 {
64 struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
65
66 netif_stop_queue(ndev);
67 netif_carrier_off(ndev);
68 cancel_delayed_work_sync(&mhi_netdev->rx_refill);
69
70 return 0;
71 }
72
mhi_ndo_xmit(struct sk_buff * skb,struct net_device * ndev)73 static netdev_tx_t mhi_ndo_xmit(struct sk_buff *skb, struct net_device *ndev)
74 {
75 struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
76 struct mhi_device *mdev = mhi_netdev->mdev;
77 int err;
78
79 err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT);
80 if (unlikely(err)) {
81 net_err_ratelimited("%s: Failed to queue TX buf (%d)\n",
82 ndev->name, err);
83 dev_kfree_skb_any(skb);
84 goto exit_drop;
85 }
86
87 if (mhi_queue_is_full(mdev, DMA_TO_DEVICE))
88 netif_stop_queue(ndev);
89
90 return NETDEV_TX_OK;
91
92 exit_drop:
93 u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
94 u64_stats_inc(&mhi_netdev->stats.tx_dropped);
95 u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
96
97 return NETDEV_TX_OK;
98 }
99
mhi_ndo_get_stats64(struct net_device * ndev,struct rtnl_link_stats64 * stats)100 static void mhi_ndo_get_stats64(struct net_device *ndev,
101 struct rtnl_link_stats64 *stats)
102 {
103 struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
104 unsigned int start;
105
106 do {
107 start = u64_stats_fetch_begin(&mhi_netdev->stats.rx_syncp);
108 stats->rx_packets = u64_stats_read(&mhi_netdev->stats.rx_packets);
109 stats->rx_bytes = u64_stats_read(&mhi_netdev->stats.rx_bytes);
110 stats->rx_errors = u64_stats_read(&mhi_netdev->stats.rx_errors);
111 } while (u64_stats_fetch_retry(&mhi_netdev->stats.rx_syncp, start));
112
113 do {
114 start = u64_stats_fetch_begin(&mhi_netdev->stats.tx_syncp);
115 stats->tx_packets = u64_stats_read(&mhi_netdev->stats.tx_packets);
116 stats->tx_bytes = u64_stats_read(&mhi_netdev->stats.tx_bytes);
117 stats->tx_errors = u64_stats_read(&mhi_netdev->stats.tx_errors);
118 stats->tx_dropped = u64_stats_read(&mhi_netdev->stats.tx_dropped);
119 } while (u64_stats_fetch_retry(&mhi_netdev->stats.tx_syncp, start));
120 }
121
122 static const struct net_device_ops mhi_netdev_ops = {
123 .ndo_open = mhi_ndo_open,
124 .ndo_stop = mhi_ndo_stop,
125 .ndo_start_xmit = mhi_ndo_xmit,
126 .ndo_get_stats64 = mhi_ndo_get_stats64,
127 };
128
mhi_net_setup(struct net_device * ndev)129 static void mhi_net_setup(struct net_device *ndev)
130 {
131 ndev->header_ops = NULL; /* No header */
132 ndev->type = ARPHRD_RAWIP;
133 ndev->hard_header_len = 0;
134 ndev->addr_len = 0;
135 ndev->flags = IFF_POINTOPOINT | IFF_NOARP;
136 ndev->netdev_ops = &mhi_netdev_ops;
137 ndev->mtu = MHI_NET_DEFAULT_MTU;
138 ndev->min_mtu = MHI_NET_MIN_MTU;
139 ndev->max_mtu = MHI_NET_MAX_MTU;
140 ndev->tx_queue_len = 1000;
141 }
142
mhi_net_skb_agg(struct mhi_net_dev * mhi_netdev,struct sk_buff * skb)143 static struct sk_buff *mhi_net_skb_agg(struct mhi_net_dev *mhi_netdev,
144 struct sk_buff *skb)
145 {
146 struct sk_buff *head = mhi_netdev->skbagg_head;
147 struct sk_buff *tail = mhi_netdev->skbagg_tail;
148
149 /* This is non-paged skb chaining using frag_list */
150 if (!head) {
151 mhi_netdev->skbagg_head = skb;
152 return skb;
153 }
154
155 if (!skb_shinfo(head)->frag_list)
156 skb_shinfo(head)->frag_list = skb;
157 else
158 tail->next = skb;
159
160 head->len += skb->len;
161 head->data_len += skb->len;
162 head->truesize += skb->truesize;
163
164 mhi_netdev->skbagg_tail = skb;
165
166 return mhi_netdev->skbagg_head;
167 }
168
mhi_net_dl_callback(struct mhi_device * mhi_dev,struct mhi_result * mhi_res)169 static void mhi_net_dl_callback(struct mhi_device *mhi_dev,
170 struct mhi_result *mhi_res)
171 {
172 struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
173 struct sk_buff *skb = mhi_res->buf_addr;
174 int free_desc_count;
175
176 free_desc_count = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
177
178 if (unlikely(mhi_res->transaction_status)) {
179 switch (mhi_res->transaction_status) {
180 case -EOVERFLOW:
181 /* Packet can not fit in one MHI buffer and has been
182 * split over multiple MHI transfers, do re-aggregation.
183 * That usually means the device side MTU is larger than
184 * the host side MTU/MRU. Since this is not optimal,
185 * print a warning (once).
186 */
187 netdev_warn_once(mhi_netdev->ndev,
188 "Fragmented packets received, fix MTU?\n");
189 skb_put(skb, mhi_res->bytes_xferd);
190 mhi_net_skb_agg(mhi_netdev, skb);
191 break;
192 case -ENOTCONN:
193 /* MHI layer stopping/resetting the DL channel */
194 dev_kfree_skb_any(skb);
195 return;
196 default:
197 /* Unknown error, simply drop */
198 dev_kfree_skb_any(skb);
199 u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
200 u64_stats_inc(&mhi_netdev->stats.rx_errors);
201 u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
202 }
203 } else {
204 skb_put(skb, mhi_res->bytes_xferd);
205
206 if (mhi_netdev->skbagg_head) {
207 /* Aggregate the final fragment */
208 skb = mhi_net_skb_agg(mhi_netdev, skb);
209 mhi_netdev->skbagg_head = NULL;
210 }
211
212 switch (skb->data[0] & 0xf0) {
213 case 0x40:
214 skb->protocol = htons(ETH_P_IP);
215 break;
216 case 0x60:
217 skb->protocol = htons(ETH_P_IPV6);
218 break;
219 default:
220 skb->protocol = htons(ETH_P_MAP);
221 break;
222 }
223
224 u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
225 u64_stats_inc(&mhi_netdev->stats.rx_packets);
226 u64_stats_add(&mhi_netdev->stats.rx_bytes, skb->len);
227 u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
228 __netif_rx(skb);
229 }
230
231 /* Refill if RX buffers queue becomes low */
232 if (free_desc_count >= mhi_netdev->rx_queue_sz / 2)
233 schedule_delayed_work(&mhi_netdev->rx_refill, 0);
234 }
235
mhi_net_ul_callback(struct mhi_device * mhi_dev,struct mhi_result * mhi_res)236 static void mhi_net_ul_callback(struct mhi_device *mhi_dev,
237 struct mhi_result *mhi_res)
238 {
239 struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
240 struct net_device *ndev = mhi_netdev->ndev;
241 struct mhi_device *mdev = mhi_netdev->mdev;
242 struct sk_buff *skb = mhi_res->buf_addr;
243
244 /* Hardware has consumed the buffer, so free the skb (which is not
245 * freed by the MHI stack) and perform accounting.
246 */
247 dev_consume_skb_any(skb);
248
249 u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
250 if (unlikely(mhi_res->transaction_status)) {
251 /* MHI layer stopping/resetting the UL channel */
252 if (mhi_res->transaction_status == -ENOTCONN) {
253 u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
254 return;
255 }
256
257 u64_stats_inc(&mhi_netdev->stats.tx_errors);
258 } else {
259 u64_stats_inc(&mhi_netdev->stats.tx_packets);
260 u64_stats_add(&mhi_netdev->stats.tx_bytes, mhi_res->bytes_xferd);
261 }
262 u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
263
264 if (netif_queue_stopped(ndev) && !mhi_queue_is_full(mdev, DMA_TO_DEVICE))
265 netif_wake_queue(ndev);
266 }
267
mhi_net_rx_refill_work(struct work_struct * work)268 static void mhi_net_rx_refill_work(struct work_struct *work)
269 {
270 struct mhi_net_dev *mhi_netdev = container_of(work, struct mhi_net_dev,
271 rx_refill.work);
272 struct net_device *ndev = mhi_netdev->ndev;
273 struct mhi_device *mdev = mhi_netdev->mdev;
274 struct sk_buff *skb;
275 unsigned int size;
276 int err;
277
278 size = mhi_netdev->mru ? mhi_netdev->mru : READ_ONCE(ndev->mtu);
279
280 while (!mhi_queue_is_full(mdev, DMA_FROM_DEVICE)) {
281 skb = netdev_alloc_skb(ndev, size);
282 if (unlikely(!skb))
283 break;
284
285 err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb, size, MHI_EOT);
286 if (unlikely(err)) {
287 net_err_ratelimited("%s: Failed to queue RX buf (%d)\n",
288 ndev->name, err);
289 kfree_skb(skb);
290 break;
291 }
292
293 /* Do not hog the CPU if rx buffers are consumed faster than
294 * queued (unlikely).
295 */
296 cond_resched();
297 }
298
299 /* If we're still starved of rx buffers, reschedule later */
300 if (mhi_get_free_desc_count(mdev, DMA_FROM_DEVICE) == mhi_netdev->rx_queue_sz)
301 schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2);
302 }
303
mhi_net_newlink(struct mhi_device * mhi_dev,struct net_device * ndev)304 static int mhi_net_newlink(struct mhi_device *mhi_dev, struct net_device *ndev)
305 {
306 struct mhi_net_dev *mhi_netdev;
307 int err;
308
309 mhi_netdev = netdev_priv(ndev);
310
311 dev_set_drvdata(&mhi_dev->dev, mhi_netdev);
312 mhi_netdev->ndev = ndev;
313 mhi_netdev->mdev = mhi_dev;
314 mhi_netdev->skbagg_head = NULL;
315 mhi_netdev->mru = mhi_dev->mhi_cntrl->mru;
316
317 INIT_DELAYED_WORK(&mhi_netdev->rx_refill, mhi_net_rx_refill_work);
318 u64_stats_init(&mhi_netdev->stats.rx_syncp);
319 u64_stats_init(&mhi_netdev->stats.tx_syncp);
320
321 /* Start MHI channels */
322 err = mhi_prepare_for_transfer(mhi_dev);
323 if (err)
324 return err;
325
326 /* Number of transfer descriptors determines size of the queue */
327 mhi_netdev->rx_queue_sz = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
328
329 err = register_netdev(ndev);
330 if (err)
331 return err;
332
333 return 0;
334 }
335
mhi_net_dellink(struct mhi_device * mhi_dev,struct net_device * ndev)336 static void mhi_net_dellink(struct mhi_device *mhi_dev, struct net_device *ndev)
337 {
338 struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
339
340 unregister_netdev(ndev);
341
342 mhi_unprepare_from_transfer(mhi_dev);
343
344 kfree_skb(mhi_netdev->skbagg_head);
345
346 free_netdev(ndev);
347
348 dev_set_drvdata(&mhi_dev->dev, NULL);
349 }
350
mhi_net_probe(struct mhi_device * mhi_dev,const struct mhi_device_id * id)351 static int mhi_net_probe(struct mhi_device *mhi_dev,
352 const struct mhi_device_id *id)
353 {
354 const struct mhi_device_info *info = (struct mhi_device_info *)id->driver_data;
355 struct net_device *ndev;
356 int err;
357
358 ndev = alloc_netdev(sizeof(struct mhi_net_dev), info->netname,
359 NET_NAME_PREDICTABLE, mhi_net_setup);
360 if (!ndev)
361 return -ENOMEM;
362
363 SET_NETDEV_DEV(ndev, &mhi_dev->dev);
364
365 err = mhi_net_newlink(mhi_dev, ndev);
366 if (err) {
367 free_netdev(ndev);
368 return err;
369 }
370
371 return 0;
372 }
373
mhi_net_remove(struct mhi_device * mhi_dev)374 static void mhi_net_remove(struct mhi_device *mhi_dev)
375 {
376 struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
377
378 mhi_net_dellink(mhi_dev, mhi_netdev->ndev);
379 }
380
381 static const struct mhi_device_info mhi_hwip0 = {
382 .netname = "mhi_hwip%d",
383 };
384
385 static const struct mhi_device_info mhi_swip0 = {
386 .netname = "mhi_swip%d",
387 };
388
389 static const struct mhi_device_id mhi_net_id_table[] = {
390 /* Hardware accelerated data PATH (to modem IPA), protocol agnostic */
391 { .chan = "IP_HW0", .driver_data = (kernel_ulong_t)&mhi_hwip0 },
392 /* Software data PATH (to modem CPU) */
393 { .chan = "IP_SW0", .driver_data = (kernel_ulong_t)&mhi_swip0 },
394 {}
395 };
396 MODULE_DEVICE_TABLE(mhi, mhi_net_id_table);
397
398 static struct mhi_driver mhi_net_driver = {
399 .probe = mhi_net_probe,
400 .remove = mhi_net_remove,
401 .dl_xfer_cb = mhi_net_dl_callback,
402 .ul_xfer_cb = mhi_net_ul_callback,
403 .id_table = mhi_net_id_table,
404 .driver = {
405 .name = "mhi_net",
406 },
407 };
408
409 module_mhi_driver(mhi_net_driver);
410
411 MODULE_AUTHOR("Loic Poulain <loic.poulain@linaro.org>");
412 MODULE_DESCRIPTION("Network over MHI");
413 MODULE_LICENSE("GPL v2");
414