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 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 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 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 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 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 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 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 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 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