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// SPDX-License-Identifier: GPL-2.0-or-later
/* MHI Network driver - Network over MHI bus
*
* Copyright (C) 2020 Linaro Ltd <loic.poulain@linaro.org>
*/
#include <linux/if_arp.h>
#include <linux/mhi.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/u64_stats_sync.h>
#define MHI_NET_MIN_MTU ETH_MIN_MTU
#define MHI_NET_MAX_MTU 0xffff
#define MHI_NET_DEFAULT_MTU 0x4000
struct mhi_net_stats {
u64_stats_t rx_packets;
u64_stats_t rx_bytes;
u64_stats_t rx_errors;
u64_stats_t rx_dropped;
u64_stats_t tx_packets;
u64_stats_t tx_bytes;
u64_stats_t tx_errors;
u64_stats_t tx_dropped;
atomic_t rx_queued;
struct u64_stats_sync tx_syncp;
struct u64_stats_sync rx_syncp;
};
struct mhi_net_dev {
struct mhi_device *mdev;
struct net_device *ndev;
struct delayed_work rx_refill;
struct mhi_net_stats stats;
u32 rx_queue_sz;
};
static int mhi_ndo_open(struct net_device *ndev)
{
struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
/* Feed the rx buffer pool */
schedule_delayed_work(&mhi_netdev->rx_refill, 0);
/* Carrier is established via out-of-band channel (e.g. qmi) */
netif_carrier_on(ndev);
netif_start_queue(ndev);
return 0;
}
static int mhi_ndo_stop(struct net_device *ndev)
{
struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
netif_stop_queue(ndev);
netif_carrier_off(ndev);
cancel_delayed_work_sync(&mhi_netdev->rx_refill);
return 0;
}
static int mhi_ndo_xmit(struct sk_buff *skb, struct net_device *ndev)
{
struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
struct mhi_device *mdev = mhi_netdev->mdev;
int err;
err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT);
if (unlikely(err)) {
net_err_ratelimited("%s: Failed to queue TX buf (%d)\n",
ndev->name, err);
u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
u64_stats_inc(&mhi_netdev->stats.tx_dropped);
u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
/* drop the packet */
dev_kfree_skb_any(skb);
}
if (mhi_queue_is_full(mdev, DMA_TO_DEVICE))
netif_stop_queue(ndev);
return NETDEV_TX_OK;
}
static void mhi_ndo_get_stats64(struct net_device *ndev,
struct rtnl_link_stats64 *stats)
{
struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
unsigned int start;
do {
start = u64_stats_fetch_begin_irq(&mhi_netdev->stats.rx_syncp);
stats->rx_packets = u64_stats_read(&mhi_netdev->stats.rx_packets);
stats->rx_bytes = u64_stats_read(&mhi_netdev->stats.rx_bytes);
stats->rx_errors = u64_stats_read(&mhi_netdev->stats.rx_errors);
stats->rx_dropped = u64_stats_read(&mhi_netdev->stats.rx_dropped);
} while (u64_stats_fetch_retry_irq(&mhi_netdev->stats.rx_syncp, start));
do {
start = u64_stats_fetch_begin_irq(&mhi_netdev->stats.tx_syncp);
stats->tx_packets = u64_stats_read(&mhi_netdev->stats.tx_packets);
stats->tx_bytes = u64_stats_read(&mhi_netdev->stats.tx_bytes);
stats->tx_errors = u64_stats_read(&mhi_netdev->stats.tx_errors);
stats->tx_dropped = u64_stats_read(&mhi_netdev->stats.tx_dropped);
} while (u64_stats_fetch_retry_irq(&mhi_netdev->stats.tx_syncp, start));
}
static const struct net_device_ops mhi_netdev_ops = {
.ndo_open = mhi_ndo_open,
.ndo_stop = mhi_ndo_stop,
.ndo_start_xmit = mhi_ndo_xmit,
.ndo_get_stats64 = mhi_ndo_get_stats64,
};
static void mhi_net_setup(struct net_device *ndev)
{
ndev->header_ops = NULL; /* No header */
ndev->type = ARPHRD_RAWIP;
ndev->hard_header_len = 0;
ndev->addr_len = 0;
ndev->flags = IFF_POINTOPOINT | IFF_NOARP;
ndev->netdev_ops = &mhi_netdev_ops;
ndev->mtu = MHI_NET_DEFAULT_MTU;
ndev->min_mtu = MHI_NET_MIN_MTU;
ndev->max_mtu = MHI_NET_MAX_MTU;
ndev->tx_queue_len = 1000;
}
static void mhi_net_dl_callback(struct mhi_device *mhi_dev,
struct mhi_result *mhi_res)
{
struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
struct sk_buff *skb = mhi_res->buf_addr;
int remaining;
remaining = atomic_dec_return(&mhi_netdev->stats.rx_queued);
if (unlikely(mhi_res->transaction_status)) {
dev_kfree_skb_any(skb);
/* MHI layer stopping/resetting the DL channel */
if (mhi_res->transaction_status == -ENOTCONN)
return;
u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
u64_stats_inc(&mhi_netdev->stats.rx_errors);
u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
} else {
u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
u64_stats_inc(&mhi_netdev->stats.rx_packets);
u64_stats_add(&mhi_netdev->stats.rx_bytes, mhi_res->bytes_xferd);
u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
switch (skb->data[0] & 0xf0) {
case 0x40:
skb->protocol = htons(ETH_P_IP);
break;
case 0x60:
skb->protocol = htons(ETH_P_IPV6);
break;
default:
skb->protocol = htons(ETH_P_MAP);
break;
}
skb_put(skb, mhi_res->bytes_xferd);
netif_rx(skb);
}
/* Refill if RX buffers queue becomes low */
if (remaining <= mhi_netdev->rx_queue_sz / 2)
schedule_delayed_work(&mhi_netdev->rx_refill, 0);
}
static void mhi_net_ul_callback(struct mhi_device *mhi_dev,
struct mhi_result *mhi_res)
{
struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
struct net_device *ndev = mhi_netdev->ndev;
struct mhi_device *mdev = mhi_netdev->mdev;
struct sk_buff *skb = mhi_res->buf_addr;
/* Hardware has consumed the buffer, so free the skb (which is not
* freed by the MHI stack) and perform accounting.
*/
dev_consume_skb_any(skb);
u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
if (unlikely(mhi_res->transaction_status)) {
/* MHI layer stopping/resetting the UL channel */
if (mhi_res->transaction_status == -ENOTCONN) {
u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
return;
}
u64_stats_inc(&mhi_netdev->stats.tx_errors);
} else {
u64_stats_inc(&mhi_netdev->stats.tx_packets);
u64_stats_add(&mhi_netdev->stats.tx_bytes, mhi_res->bytes_xferd);
}
u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
if (netif_queue_stopped(ndev) && !mhi_queue_is_full(mdev, DMA_TO_DEVICE))
netif_wake_queue(ndev);
}
static void mhi_net_rx_refill_work(struct work_struct *work)
{
struct mhi_net_dev *mhi_netdev = container_of(work, struct mhi_net_dev,
rx_refill.work);
struct net_device *ndev = mhi_netdev->ndev;
struct mhi_device *mdev = mhi_netdev->mdev;
int size = READ_ONCE(ndev->mtu);
struct sk_buff *skb;
int err;
while (atomic_read(&mhi_netdev->stats.rx_queued) < mhi_netdev->rx_queue_sz) {
skb = netdev_alloc_skb(ndev, size);
if (unlikely(!skb))
break;
err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb, size, MHI_EOT);
if (unlikely(err)) {
net_err_ratelimited("%s: Failed to queue RX buf (%d)\n",
ndev->name, err);
kfree_skb(skb);
break;
}
atomic_inc(&mhi_netdev->stats.rx_queued);
/* Do not hog the CPU if rx buffers are consumed faster than
* queued (unlikely).
*/
cond_resched();
}
/* If we're still starved of rx buffers, reschedule later */
if (unlikely(!atomic_read(&mhi_netdev->stats.rx_queued)))
schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2);
}
static struct device_type wwan_type = {
.name = "wwan",
};
static int mhi_net_probe(struct mhi_device *mhi_dev,
const struct mhi_device_id *id)
{
const char *netname = (char *)id->driver_data;
struct device *dev = &mhi_dev->dev;
struct mhi_net_dev *mhi_netdev;
struct net_device *ndev;
int err;
ndev = alloc_netdev(sizeof(*mhi_netdev), netname, NET_NAME_PREDICTABLE,
mhi_net_setup);
if (!ndev)
return -ENOMEM;
mhi_netdev = netdev_priv(ndev);
dev_set_drvdata(dev, mhi_netdev);
mhi_netdev->ndev = ndev;
mhi_netdev->mdev = mhi_dev;
SET_NETDEV_DEV(ndev, &mhi_dev->dev);
SET_NETDEV_DEVTYPE(ndev, &wwan_type);
/* All MHI net channels have 128 ring elements (at least for now) */
mhi_netdev->rx_queue_sz = 128;
INIT_DELAYED_WORK(&mhi_netdev->rx_refill, mhi_net_rx_refill_work);
u64_stats_init(&mhi_netdev->stats.rx_syncp);
u64_stats_init(&mhi_netdev->stats.tx_syncp);
/* Start MHI channels */
err = mhi_prepare_for_transfer(mhi_dev);
if (err)
goto out_err;
err = register_netdev(ndev);
if (err)
goto out_err;
return 0;
out_err:
free_netdev(ndev);
return err;
}
static void mhi_net_remove(struct mhi_device *mhi_dev)
{
struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
unregister_netdev(mhi_netdev->ndev);
mhi_unprepare_from_transfer(mhi_netdev->mdev);
free_netdev(mhi_netdev->ndev);
}
static const struct mhi_device_id mhi_net_id_table[] = {
{ .chan = "IP_HW0", .driver_data = (kernel_ulong_t)"mhi_hwip%d" },
{ .chan = "IP_SW0", .driver_data = (kernel_ulong_t)"mhi_swip%d" },
{}
};
MODULE_DEVICE_TABLE(mhi, mhi_net_id_table);
static struct mhi_driver mhi_net_driver = {
.probe = mhi_net_probe,
.remove = mhi_net_remove,
.dl_xfer_cb = mhi_net_dl_callback,
.ul_xfer_cb = mhi_net_ul_callback,
.id_table = mhi_net_id_table,
.driver = {
.name = "mhi_net",
.owner = THIS_MODULE,
},
};
module_mhi_driver(mhi_net_driver);
MODULE_AUTHOR("Loic Poulain <loic.poulain@linaro.org>");
MODULE_DESCRIPTION("Network over MHI");
MODULE_LICENSE("GPL v2");
|