[PATCH v5 1/3] net: mhi : Add support to enable ethernet interface

From: Vivek Pernamitta

Date: Thu Nov 06 2025 - 08:28:20 EST


From: Vivek Pernamitta <vivek.pernamitta@xxxxxxxxxxxxxxxx>

Currently, we only have support for the NET driver. This update allows a
new client to be configured as an Ethernet type over MHI by setting
"mhi_device_info.ethernet_if = true". A new interface for Ethernet will
be created with eth%d.

Signed-off-by: Vivek Pernamitta <vivek.pernamitta@xxxxxxxxxxxxxxxx>
---
drivers/net/mhi_net.c | 84 +++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 71 insertions(+), 13 deletions(-)

diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c
index ae169929a9d8e449b5a427993abf68e8d032fae2..aeb2d67aeb238e520dbd2a83b35602a7e5144fa2 100644
--- a/drivers/net/mhi_net.c
+++ b/drivers/net/mhi_net.c
@@ -11,6 +11,7 @@
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/u64_stats_sync.h>
+#include <linux/etherdevice.h>

#define MHI_NET_MIN_MTU ETH_MIN_MTU
#define MHI_NET_MAX_MTU 0xffff
@@ -38,10 +39,12 @@ struct mhi_net_dev {
u32 rx_queue_sz;
int msg_enable;
unsigned int mru;
+ bool ethernet_if;
};

struct mhi_device_info {
const char *netname;
+ bool ethernet_if;
};

static int mhi_ndo_open(struct net_device *ndev)
@@ -119,11 +122,37 @@ static void mhi_ndo_get_stats64(struct net_device *ndev,
} while (u64_stats_fetch_retry(&mhi_netdev->stats.tx_syncp, start));
}

+static int mhi_mac_address(struct net_device *dev, void *p)
+{
+ int ret;
+
+ if (dev->type == ARPHRD_ETHER) {
+ ret = eth_mac_addr(dev, p);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int mhi_validate_address(struct net_device *dev)
+{
+ int ret;
+
+ if (dev->type == ARPHRD_ETHER) {
+ ret = eth_validate_addr(dev);
+ return ret;
+ }
+
+ return 0;
+}
+
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,
+ .ndo_set_mac_address = mhi_mac_address,
+ .ndo_validate_addr = mhi_validate_address,
};

static void mhi_net_setup(struct net_device *ndev)
@@ -140,6 +169,14 @@ static void mhi_net_setup(struct net_device *ndev)
ndev->tx_queue_len = 1000;
}

+static void mhi_ethernet_setup(struct net_device *ndev)
+{
+ ndev->netdev_ops = &mhi_netdev_ops;
+ ether_setup(ndev);
+ ndev->min_mtu = ETH_MIN_MTU;
+ ndev->max_mtu = ETH_MAX_MTU;
+}
+
static struct sk_buff *mhi_net_skb_agg(struct mhi_net_dev *mhi_netdev,
struct sk_buff *skb)
{
@@ -209,16 +246,22 @@ static void mhi_net_dl_callback(struct mhi_device *mhi_dev,
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;
+ if (mhi_netdev->ethernet_if) {
+ skb_copy_to_linear_data(skb, skb->data,
+ mhi_res->bytes_xferd);
+ skb->protocol = eth_type_trans(skb, mhi_netdev->ndev);
+ } else {
+ 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);
@@ -301,11 +344,17 @@ static void mhi_net_rx_refill_work(struct work_struct *work)
schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2);
}

-static int mhi_net_newlink(struct mhi_device *mhi_dev, struct net_device *ndev)
+static int mhi_net_newlink(struct mhi_device *mhi_dev, struct net_device *ndev, bool eth_dev)
{
struct mhi_net_dev *mhi_netdev;
int err;

+ if (eth_dev) {
+ eth_hw_addr_random(ndev);
+ if (!is_valid_ether_addr(ndev->dev_addr))
+ return -EADDRNOTAVAIL;
+ }
+
mhi_netdev = netdev_priv(ndev);

dev_set_drvdata(&mhi_dev->dev, mhi_netdev);
@@ -313,6 +362,7 @@ static int mhi_net_newlink(struct mhi_device *mhi_dev, struct net_device *ndev)
mhi_netdev->mdev = mhi_dev;
mhi_netdev->skbagg_head = NULL;
mhi_netdev->mru = mhi_dev->mhi_cntrl->mru;
+ mhi_netdev->ethernet_if = eth_dev;

INIT_DELAYED_WORK(&mhi_netdev->rx_refill, mhi_net_rx_refill_work);
u64_stats_init(&mhi_netdev->stats.rx_syncp);
@@ -356,13 +406,14 @@ static int mhi_net_probe(struct mhi_device *mhi_dev,
int err;

ndev = alloc_netdev(sizeof(struct mhi_net_dev), info->netname,
- NET_NAME_PREDICTABLE, mhi_net_setup);
+ NET_NAME_PREDICTABLE, info->ethernet_if ?
+ mhi_ethernet_setup : mhi_net_setup);
if (!ndev)
return -ENOMEM;

SET_NETDEV_DEV(ndev, &mhi_dev->dev);

- err = mhi_net_newlink(mhi_dev, ndev);
+ err = mhi_net_newlink(mhi_dev, ndev, info->ethernet_if);
if (err) {
free_netdev(ndev);
return err;
@@ -380,10 +431,17 @@ static void mhi_net_remove(struct mhi_device *mhi_dev)

static const struct mhi_device_info mhi_hwip0 = {
.netname = "mhi_hwip%d",
+ .ethernet_if = false,
};

static const struct mhi_device_info mhi_swip0 = {
.netname = "mhi_swip%d",
+ .ethernet_if = false,
+};
+
+static const struct mhi_device_info mhi_eth0 = {
+ .netname = "eth%d",
+ .ethernet_if = true,
};

static const struct mhi_device_id mhi_net_id_table[] = {

--
2.34.1