// SPDX-License-Identifier: GPL-2.0-or-later
/* MHI Network driver - Network over MHI bus
*
* Copyright (C) 2020 Linaro Ltd <[email protected]>
*/
#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 tx_packets;
u64_stats_t tx_bytes;
u64_stats_t tx_errors;
u64_stats_t tx_dropped;
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 sk_buff *skbagg_head;
struct sk_buff *skbagg_tail;
struct delayed_work rx_refill;
struct mhi_net_stats stats;
u32 rx_queue_sz;
int msg_enable;
unsigned int mru;
};
struct mhi_device_info {
const char *netname;
};
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 netdev_tx_t 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);
dev_kfree_skb_any(skb);
goto exit_drop;
}
if (mhi_queue_is_full(mdev, DMA_TO_DEVICE))
netif_stop_queue(ndev);
return NETDEV_TX_OK;
exit_drop:
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);
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(&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);
} while (u64_stats_fetch_retry(&mhi_netdev->stats.rx_syncp, start));
do {
start = u64_stats_fetch_begin(&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(&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 struct sk_buff *mhi_net_skb_agg(struct mhi_net_dev *mhi_netdev,
struct sk_buff *skb)
{
struct sk_buff *head = mhi_netdev->skbagg_head;
struct sk_buff *tail = mhi_netdev->skbagg_tail;
/* This is non-paged skb chaining using frag_list */
if (!head) {
mhi_netdev->skbagg_head = skb;
return skb;
}
if (!skb_shinfo(head)->frag_list)
skb_shinfo(head)->frag_list = skb;
else
tail->next = skb;
head->len += skb->len;
head->data_len += skb->len;
head->truesize += skb->truesize;
mhi_netdev->skbagg_tail = skb;
return mhi_netdev->skbagg_head;
}
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 free_desc_count;
free_desc_count = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
if (unlikely(mhi_res->transaction_status)) {
switch (mhi_res->transaction_status) {
case -EOVERFLOW:
/* Packet can not fit in one MHI buffer and has been
* split over multiple MHI transfers, do re-aggregation.
* That usually means the device side MTU is larger than
* the host side MTU/MRU. Since this is not optimal,
* print a warning (once).
*/
netdev_warn_once(mhi_netdev->ndev,
"Fragmented packets received, fix MTU?\n");
skb_put(skb, mhi_res->bytes_xferd);
mhi_net_skb_agg(mhi_netdev, skb);
break;
case -ENOTCONN:
/* MHI layer stopping/resetting the DL channel */
dev_kfree_skb_any(skb);
return;
default:
/* Unknown error, simply drop */
dev_kfree_skb_any(skb);
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 {
skb_put(skb, mhi_res->bytes_xferd);
if (mhi_netdev->skbagg_head) {
/* Aggregate the final fragment */
skb = mhi_net_skb_agg(mhi_netdev, skb);
mhi_netdev->skbagg_head = NULL;
}
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;
}
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, skb->len);
u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
__netif_rx(skb);
}
/* Refill if RX buffers queue becomes low */
if (free_desc_count >= 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;
struct sk_buff *skb;
unsigned int size;
int err;
size = mhi_netdev->mru ? mhi_netdev->mru : READ_ONCE(ndev->mtu);
while (!mhi_queue_is_full(mdev, DMA_FROM_DEVICE)) {
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;
}
/* 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 (mhi_get_free_desc_count(mdev, DMA_FROM_DEVICE) == mhi_netdev->rx_queue_sz)
schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2);
}
static int mhi_net_newlink(struct mhi_device *mhi_dev, struct net_device *ndev)
{
struct mhi_net_dev *mhi_netdev;
int err;
mhi_netdev = netdev_priv(ndev);
dev_set_drvdata(&mhi_dev->dev, mhi_netdev);
mhi_netdev->ndev = ndev;
mhi_netdev->mdev = mhi_dev;
mhi_netdev->skbagg_head = NULL;
mhi_netdev->mru = mhi_dev->mhi_cntrl->mru;
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)
return err;
/* Number of transfer descriptors determines size of the queue */
mhi_netdev->rx_queue_sz = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
err = register_netdev(ndev);
if (err)
return err;
return 0;
}
static void mhi_net_dellink(struct mhi_device *mhi_dev, struct net_device *ndev)
{
struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
unregister_netdev(ndev);
mhi_unprepare_from_transfer(mhi_dev);
kfree_skb(mhi_netdev->skbagg_head);
free_netdev(ndev);
dev_set_drvdata(&mhi_dev->dev, NULL);
}
static int mhi_net_probe(struct mhi_device *mhi_dev,
const struct mhi_device_id *id)
{
const struct mhi_device_info *info = (struct mhi_device_info *)id->driver_data;
struct net_device *ndev;
int err;
ndev = alloc_netdev(sizeof(struct mhi_net_dev), info->netname,
NET_NAME_PREDICTABLE, mhi_net_setup);
if (!ndev)
return -ENOMEM;
SET_NETDEV_DEV(ndev, &mhi_dev->dev);
err = mhi_net_newlink(mhi_dev, ndev);
if (err) {
free_netdev(ndev);
return err;
}
return 0;
}
static void mhi_net_remove(struct mhi_device *mhi_dev)
{
struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
mhi_net_dellink(mhi_dev, mhi_netdev->ndev);
}
static const struct mhi_device_info mhi_hwip0 = {
.netname = "mhi_hwip%d",
};
static const struct mhi_device_info mhi_swip0 = {
.netname = "mhi_swip%d",
};
static const struct mhi_device_id mhi_net_id_table[] = {
/* Hardware accelerated data PATH (to modem IPA), protocol agnostic */
{ .chan = "IP_HW0", .driver_data = (kernel_ulong_t)&mhi_hwip0 },
/* Software data PATH (to modem CPU) */
{ .chan = "IP_SW0", .driver_data = (kernel_ulong_t)&mhi_swip0 },
{}
};
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",
},
};
module_mhi_driver(mhi_net_driver);
MODULE_AUTHOR("Loic Poulain <[email protected]>");
MODULE_DESCRIPTION("Network over MHI");
MODULE_LICENSE("GPL v2");
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