LXR linux/drivers/net/mhi

   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_irq(&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_irq(&mhi_netdev->stats.rx_syncp, start));
 112
 113        do {
 114                start = u64_stats_fetch_begin_irq(&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_irq(&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        dev_set_drvdata(&mhi_dev->dev, NULL);
 347}
 348
 349static int mhi_net_probe(struct mhi_device *mhi_dev,
 350                         const struct mhi_device_id *id)
 351{
 352        const struct mhi_device_info *info = (struct mhi_device_info *)id->driver_data;
 353        struct net_device *ndev;
 354        int err;
 355
 356        ndev = alloc_netdev(sizeof(struct mhi_net_dev), info->netname,
 357                            NET_NAME_PREDICTABLE, mhi_net_setup);
 358        if (!ndev)
 359                return -ENOMEM;
 360
 361        SET_NETDEV_DEV(ndev, &mhi_dev->dev);
 362
 363        err = mhi_net_newlink(mhi_dev, ndev);
 364        if (err) {
 365                free_netdev(ndev);
 366                return err;
 367        }
 368
 369        return 0;
 370}
 371
 372static void mhi_net_remove(struct mhi_device *mhi_dev)
 373{
 374        struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
 375
 376        mhi_net_dellink(mhi_dev, mhi_netdev->ndev);
 377}
 378
 379static const struct mhi_device_info mhi_hwip0 = {
 380        .netname = "mhi_hwip%d",
 381};
 382
 383static const struct mhi_device_info mhi_swip0 = {
 384        .netname = "mhi_swip%d",
 385};
 386
 387static const struct mhi_device_id mhi_net_id_table[] = {
 388        /* Hardware accelerated data PATH (to modem IPA), protocol agnostic */
 389        { .chan = "IP_HW0", .driver_data = (kernel_ulong_t)&mhi_hwip0 },
 390        /* Software data PATH (to modem CPU) */
 391        { .chan = "IP_SW0", .driver_data = (kernel_ulong_t)&mhi_swip0 },
 392        {}
 393};
 394MODULE_DEVICE_TABLE(mhi, mhi_net_id_table);
 395
 396static struct mhi_driver mhi_net_driver = {
 397        .probe = mhi_net_probe,
 398        .remove = mhi_net_remove,
 399        .dl_xfer_cb = mhi_net_dl_callback,
 400        .ul_xfer_cb = mhi_net_ul_callback,
 401        .id_table = mhi_net_id_table,
 402        .driver = {
 403                .name = "mhi_net",
 404                .owner = THIS_MODULE,
 405        },
 406};
 407
 408module_mhi_driver(mhi_net_driver);
 409
 410MODULE_AUTHOR("Loic Poulain <loic.poulain@linaro.org>");
 411MODULE_DESCRIPTION("Network over MHI");
 412MODULE_LICENSE("GPL v2");
 413