414 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/* MHI Network driver - Network over MHI bus3 *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_MTU16#define MHI_NET_MAX_MTU 0xffff17#define MHI_NET_DEFAULT_MTU 0x400018 19struct 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 31struct 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 43struct mhi_device_info {44 const char *netname;45};46 47static 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 62static 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 73static 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 92exit_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 100static 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 122static 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 129static 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 143static 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 else158 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 169static 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 been182 * split over multiple MHI transfers, do re-aggregation.183 * That usually means the device side MTU is larger than184 * 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 236static 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 not245 * 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 268static 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 than294 * 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 304static 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 336static 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 351static 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 374static 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 381static const struct mhi_device_info mhi_hwip0 = {382 .netname = "mhi_hwip%d",383};384 385static const struct mhi_device_info mhi_swip0 = {386 .netname = "mhi_swip%d",387};388 389static 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};396MODULE_DEVICE_TABLE(mhi, mhi_net_id_table);397 398static 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 409module_mhi_driver(mhi_net_driver);410 411MODULE_AUTHOR("Loic Poulain <loic.poulain@linaro.org>");412MODULE_DESCRIPTION("Network over MHI");413MODULE_LICENSE("GPL v2");414