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 rx_dropped;
  24        u64_stats_t tx_packets;
  25        u64_stats_t tx_bytes;
  26        u64_stats_t tx_errors;
  27        u64_stats_t tx_dropped;
  28        atomic_t rx_queued;
  29        struct u64_stats_sync tx_syncp;
  30        struct u64_stats_sync rx_syncp;
  31};
  32
  33struct mhi_net_dev {
  34        struct mhi_device *mdev;
  35        struct net_device *ndev;
  36        struct delayed_work rx_refill;
  37        struct mhi_net_stats stats;
  38        u32 rx_queue_sz;
  39};
  40
  41static int mhi_ndo_open(struct net_device *ndev)
  42{
  43        struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
  44
  45        /* Feed the rx buffer pool */
  46        schedule_delayed_work(&mhi_netdev->rx_refill, 0);
  47
  48        /* Carrier is established via out-of-band channel (e.g. qmi) */
  49        netif_carrier_on(ndev);
  50
  51        netif_start_queue(ndev);
  52
  53        return 0;
  54}
  55
  56static int mhi_ndo_stop(struct net_device *ndev)
  57{
  58        struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
  59
  60        netif_stop_queue(ndev);
  61        netif_carrier_off(ndev);
  62        cancel_delayed_work_sync(&mhi_netdev->rx_refill);
  63
  64        return 0;
  65}
  66
  67static int mhi_ndo_xmit(struct sk_buff *skb, struct net_device *ndev)
  68{
  69        struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
  70        struct mhi_device *mdev = mhi_netdev->mdev;
  71        int err;
  72
  73        err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT);
  74        if (unlikely(err)) {
  75                net_err_ratelimited("%s: Failed to queue TX buf (%d)\n",
  76                                    ndev->name, err);
  77
  78                u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
  79                u64_stats_inc(&mhi_netdev->stats.tx_dropped);
  80                u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
  81
  82                /* drop the packet */
  83                dev_kfree_skb_any(skb);
  84        }
  85
  86        if (mhi_queue_is_full(mdev, DMA_TO_DEVICE))
  87                netif_stop_queue(ndev);
  88
  89        return NETDEV_TX_OK;
  90}
  91
  92static void mhi_ndo_get_stats64(struct net_device *ndev,
  93                                struct rtnl_link_stats64 *stats)
  94{
  95        struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
  96        unsigned int start;
  97
  98        do {
  99                start = u64_stats_fetch_begin_irq(&mhi_netdev->stats.rx_syncp);
 100                stats->rx_packets = u64_stats_read(&mhi_netdev->stats.rx_packets);
 101                stats->rx_bytes = u64_stats_read(&mhi_netdev->stats.rx_bytes);
 102                stats->rx_errors = u64_stats_read(&mhi_netdev->stats.rx_errors);
 103                stats->rx_dropped = u64_stats_read(&mhi_netdev->stats.rx_dropped);
 104        } while (u64_stats_fetch_retry_irq(&mhi_netdev->stats.rx_syncp, start));
 105
 106        do {
 107                start = u64_stats_fetch_begin_irq(&mhi_netdev->stats.tx_syncp);
 108                stats->tx_packets = u64_stats_read(&mhi_netdev->stats.tx_packets);
 109                stats->tx_bytes = u64_stats_read(&mhi_netdev->stats.tx_bytes);
 110                stats->tx_errors = u64_stats_read(&mhi_netdev->stats.tx_errors);
 111                stats->tx_dropped = u64_stats_read(&mhi_netdev->stats.tx_dropped);
 112        } while (u64_stats_fetch_retry_irq(&mhi_netdev->stats.tx_syncp, start));
 113}
 114
 115static const struct net_device_ops mhi_netdev_ops = {
 116        .ndo_open               = mhi_ndo_open,
 117        .ndo_stop               = mhi_ndo_stop,
 118        .ndo_start_xmit         = mhi_ndo_xmit,
 119        .ndo_get_stats64        = mhi_ndo_get_stats64,
 120};
 121
 122static void mhi_net_setup(struct net_device *ndev)
 123{
 124        ndev->header_ops = NULL;  /* No header */
 125        ndev->type = ARPHRD_NONE; /* QMAP... */
 126        ndev->hard_header_len = 0;
 127        ndev->addr_len = 0;
 128        ndev->flags = IFF_POINTOPOINT | IFF_NOARP;
 129        ndev->netdev_ops = &mhi_netdev_ops;
 130        ndev->mtu = MHI_NET_DEFAULT_MTU;
 131        ndev->min_mtu = MHI_NET_MIN_MTU;
 132        ndev->max_mtu = MHI_NET_MAX_MTU;
 133        ndev->tx_queue_len = 1000;
 134}
 135
 136static void mhi_net_dl_callback(struct mhi_device *mhi_dev,
 137                                struct mhi_result *mhi_res)
 138{
 139        struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
 140        struct sk_buff *skb = mhi_res->buf_addr;
 141        int remaining;
 142
 143        remaining = atomic_dec_return(&mhi_netdev->stats.rx_queued);
 144
 145        if (unlikely(mhi_res->transaction_status)) {
 146                dev_kfree_skb_any(skb);
 147
 148                /* MHI layer stopping/resetting the DL channel */
 149                if (mhi_res->transaction_status == -ENOTCONN)
 150                        return;
 151
 152                u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
 153                u64_stats_inc(&mhi_netdev->stats.rx_errors);
 154                u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
 155        } else {
 156                u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
 157                u64_stats_inc(&mhi_netdev->stats.rx_packets);
 158                u64_stats_add(&mhi_netdev->stats.rx_bytes, mhi_res->bytes_xferd);
 159                u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
 160
 161                skb->protocol = htons(ETH_P_MAP);
 162                skb_put(skb, mhi_res->bytes_xferd);
 163                netif_rx(skb);
 164        }
 165
 166        /* Refill if RX buffers queue becomes low */
 167        if (remaining <= mhi_netdev->rx_queue_sz / 2)
 168                schedule_delayed_work(&mhi_netdev->rx_refill, 0);
 169}
 170
 171static void mhi_net_ul_callback(struct mhi_device *mhi_dev,
 172                                struct mhi_result *mhi_res)
 173{
 174        struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
 175        struct net_device *ndev = mhi_netdev->ndev;
 176        struct mhi_device *mdev = mhi_netdev->mdev;
 177        struct sk_buff *skb = mhi_res->buf_addr;
 178
 179        /* Hardware has consumed the buffer, so free the skb (which is not
 180         * freed by the MHI stack) and perform accounting.
 181         */
 182        dev_consume_skb_any(skb);
 183
 184        u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
 185        if (unlikely(mhi_res->transaction_status)) {
 186
 187                /* MHI layer stopping/resetting the UL channel */
 188                if (mhi_res->transaction_status == -ENOTCONN) {
 189                        u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
 190                        return;
 191                }
 192
 193                u64_stats_inc(&mhi_netdev->stats.tx_errors);
 194        } else {
 195                u64_stats_inc(&mhi_netdev->stats.tx_packets);
 196                u64_stats_add(&mhi_netdev->stats.tx_bytes, mhi_res->bytes_xferd);
 197        }
 198        u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
 199
 200        if (netif_queue_stopped(ndev) && !mhi_queue_is_full(mdev, DMA_TO_DEVICE))
 201                netif_wake_queue(ndev);
 202}
 203
 204static void mhi_net_rx_refill_work(struct work_struct *work)
 205{
 206        struct mhi_net_dev *mhi_netdev = container_of(work, struct mhi_net_dev,
 207                                                      rx_refill.work);
 208        struct net_device *ndev = mhi_netdev->ndev;
 209        struct mhi_device *mdev = mhi_netdev->mdev;
 210        int size = READ_ONCE(ndev->mtu);
 211        struct sk_buff *skb;
 212        int err;
 213
 214        while (atomic_read(&mhi_netdev->stats.rx_queued) < mhi_netdev->rx_queue_sz) {
 215                skb = netdev_alloc_skb(ndev, size);
 216                if (unlikely(!skb))
 217                        break;
 218
 219                err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb, size, MHI_EOT);
 220                if (unlikely(err)) {
 221                        net_err_ratelimited("%s: Failed to queue RX buf (%d)\n",
 222                                            ndev->name, err);
 223                        kfree_skb(skb);
 224                        break;
 225                }
 226
 227                atomic_inc(&mhi_netdev->stats.rx_queued);
 228
 229                /* Do not hog the CPU if rx buffers are consumed faster than
 230                 * queued (unlikely).
 231                 */
 232                cond_resched();
 233        }
 234
 235        /* If we're still starved of rx buffers, reschedule later */
 236        if (unlikely(!atomic_read(&mhi_netdev->stats.rx_queued)))
 237                schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2);
 238}
 239
 240static int mhi_net_probe(struct mhi_device *mhi_dev,
 241                         const struct mhi_device_id *id)
 242{
 243        const char *netname = (char *)id->driver_data;
 244        struct device *dev = &mhi_dev->dev;
 245        struct mhi_net_dev *mhi_netdev;
 246        struct net_device *ndev;
 247        int err;
 248
 249        ndev = alloc_netdev(sizeof(*mhi_netdev), netname, NET_NAME_PREDICTABLE,
 250                            mhi_net_setup);
 251        if (!ndev)
 252                return -ENOMEM;
 253
 254        mhi_netdev = netdev_priv(ndev);
 255        dev_set_drvdata(dev, mhi_netdev);
 256        mhi_netdev->ndev = ndev;
 257        mhi_netdev->mdev = mhi_dev;
 258        SET_NETDEV_DEV(ndev, &mhi_dev->dev);
 259
 260        /* All MHI net channels have 128 ring elements (at least for now) */
 261        mhi_netdev->rx_queue_sz = 128;
 262
 263        INIT_DELAYED_WORK(&mhi_netdev->rx_refill, mhi_net_rx_refill_work);
 264        u64_stats_init(&mhi_netdev->stats.rx_syncp);
 265        u64_stats_init(&mhi_netdev->stats.tx_syncp);
 266
 267        /* Start MHI channels */
 268        err = mhi_prepare_for_transfer(mhi_dev);
 269        if (err)
 270                goto out_err;
 271
 272        err = register_netdev(ndev);
 273        if (err)
 274                goto out_err;
 275
 276        return 0;
 277
 278out_err:
 279        free_netdev(ndev);
 280        return err;
 281}
 282
 283static void mhi_net_remove(struct mhi_device *mhi_dev)
 284{
 285        struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
 286
 287        unregister_netdev(mhi_netdev->ndev);
 288
 289        mhi_unprepare_from_transfer(mhi_netdev->mdev);
 290
 291        free_netdev(mhi_netdev->ndev);
 292}
 293
 294static const struct mhi_device_id mhi_net_id_table[] = {
 295        { .chan = "IP_HW0", .driver_data = (kernel_ulong_t)"mhi_hwip%d" },
 296        { .chan = "IP_SW0", .driver_data = (kernel_ulong_t)"mhi_swip%d" },
 297        {}
 298};
 299MODULE_DEVICE_TABLE(mhi, mhi_net_id_table);
 300
 301static struct mhi_driver mhi_net_driver = {
 302        .probe = mhi_net_probe,
 303        .remove = mhi_net_remove,
 304        .dl_xfer_cb = mhi_net_dl_callback,
 305        .ul_xfer_cb = mhi_net_ul_callback,
 306        .id_table = mhi_net_id_table,
 307        .driver = {
 308                .name = "mhi_net",
 309                .owner = THIS_MODULE,
 310        },
 311};
 312
 313module_mhi_driver(mhi_net_driver);
 314
 315MODULE_AUTHOR("Loic Poulain <loic.poulain@linaro.org>");
 316MODULE_DESCRIPTION("Network over MHI");
 317MODULE_LICENSE("GPL v2");
 318