| Message ID | 1602757888-3507-1-git-send-email-loic.poulain@linaro.org (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v4,1/2] net: Add mhi-net driver | expand |
Please ignore this one, the title is wrong (it's not patch 1/2). On Thu, 15 Oct 2020 at 12:25, Loic Poulain <loic.poulain@linaro.org> wrote: > > This patch adds a new network driver implementing MHI transport for > network packets. Packets can be in any format, though QMAP (rmnet) > is the usual protocol (flow control + PDN mux). > > It support two MHI devices, IP_HW0 which is, the path to the IPA > (IP accelerator) on qcom modem, And IP_SW0 which is the software > driven IP path (to modem CPU). > > Signed-off-by: Loic Poulain <loic.poulain@linaro.org> > --- > v2: - rebase on net-next > - remove useless skb_linearize > - check error type on mhi_queue return > - rate limited errors > - Schedule RX refill only on 'low' buf level > - SET_NETDEV_DEV in probe > - reorder device remove sequence > v3: - Stop channels on net_register error > - Remove useles parentheses > - Add driver .owner > v4: - prevent potential cpu hog in rx-refill loop > - Access mtu via READ_ONCE > > drivers/net/Kconfig | 7 ++ > drivers/net/Makefile | 1 + > drivers/net/mhi_net.c | 289 ++++++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 297 insertions(+) > create mode 100644 drivers/net/mhi_net.c > > diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig > index 1368d1d..11a6357 100644 > --- a/drivers/net/Kconfig > +++ b/drivers/net/Kconfig > @@ -426,6 +426,13 @@ config VSOCKMON > mostly intended for developers or support to debug vsock issues. If > unsure, say N. > > +config MHI_NET > + tristate "MHI network driver" > + depends on MHI_BUS > + help > + This is the network driver for MHI. It can be used with > + QCOM based WWAN modems (like SDX55). Say Y or M. > + > endif # NET_CORE > > config SUNGEM_PHY > diff --git a/drivers/net/Makefile b/drivers/net/Makefile > index 94b6080..8312037 100644 > --- a/drivers/net/Makefile > +++ b/drivers/net/Makefile > @@ -34,6 +34,7 @@ obj-$(CONFIG_GTP) += gtp.o > obj-$(CONFIG_NLMON) += nlmon.o > obj-$(CONFIG_NET_VRF) += vrf.o > obj-$(CONFIG_VSOCKMON) += vsockmon.o > +obj-$(CONFIG_MHI_NET) += mhi_net.o > > # > # Networking Drivers > diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c > new file mode 100644 > index 0000000..fe605a4 > --- /dev/null > +++ b/drivers/net/mhi_net.c > @@ -0,0 +1,289 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* MHI Network driver - Network over MHI > + * > + * 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> > + > +#define MIN_MTU ETH_MIN_MTU > +#define MAX_MTU 0xffff > +#define DEFAULT_MTU 8192 > + > +struct mhi_net_stats { > + u64 rx_packets; > + u64 rx_bytes; > + u64 rx_errors; > + u64 rx_dropped; > + u64 tx_packets; > + u64 tx_bytes; > + u64 tx_errors; > + u64 tx_dropped; > + atomic_t rx_queued; > +}; > + > +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; > + > + skb_tx_timestamp(skb); > + > + /* mhi_queue_skb is not thread-safe, but xmit is serialized by the > + * network core. Once MHI core will be thread save, migrate to > + * NETIF_F_LLTX support. > + */ > + err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT); > + if (err == -ENOMEM) { > + netif_stop_queue(ndev); > + return NETDEV_TX_BUSY; > + } else if (unlikely(err)) { > + net_err_ratelimited("%s: Failed to queue TX buf (%d)\n", > + ndev->name, err); > + mhi_netdev->stats.tx_dropped++; > + kfree_skb(skb); > + } > + > + 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); > + > + stats->rx_packets = mhi_netdev->stats.rx_packets; > + stats->rx_bytes = mhi_netdev->stats.rx_bytes; > + stats->rx_errors = mhi_netdev->stats.rx_errors; > + stats->rx_dropped = mhi_netdev->stats.rx_dropped; > + stats->tx_packets = mhi_netdev->stats.tx_packets; > + stats->tx_bytes = mhi_netdev->stats.tx_bytes; > + stats->tx_errors = mhi_netdev->stats.tx_errors; > + stats->tx_dropped = mhi_netdev->stats.tx_dropped; > +} > + > +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_NONE; /* QMAP... */ > + ndev->hard_header_len = 0; > + ndev->addr_len = 0; > + ndev->flags = IFF_POINTOPOINT | IFF_NOARP; > + ndev->netdev_ops = &mhi_netdev_ops; > + ndev->mtu = DEFAULT_MTU; > + ndev->min_mtu = MIN_MTU; > + ndev->max_mtu = 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)) { > + mhi_netdev->stats.rx_errors++; > + kfree_skb(skb); > + } else { > + mhi_netdev->stats.rx_packets++; > + mhi_netdev->stats.rx_bytes += mhi_res->bytes_xferd; > + > + skb->protocol = htons(ETH_P_MAP); > + 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 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. > + */ > + consume_skb(skb); > + > + if (unlikely(mhi_res->transaction_status)) { > + mhi_netdev->stats.tx_errors++; > + } else { > + mhi_netdev->stats.tx_packets++; > + mhi_netdev->stats.tx_bytes += mhi_res->bytes_xferd; > + } > + > + if (netif_queue_stopped(ndev)) > + 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; > + > + do { > + skb = netdev_alloc_skb(ndev, size); > + if (unlikely(!skb)) > + break; > + > + err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb, size, MHI_EOT); > + if (err) { > + if (unlikely(err != -ENOMEM)) > + 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 completed faster than > + * queued (unlikely). > + */ > + cond_resched(); > + } while (1); > + > + /* If we're still starved of rx buffers, reschedule latter */ > + if (unlikely(!atomic_read(&mhi_netdev->stats.rx_queued))) > + schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2); > +} > + > +static int mhi_net_probe(struct mhi_device *mhi_dev, > + const struct mhi_device_id *id) > +{ > + const char *netname = (char *)id->driver_data; > + struct mhi_net_dev *mhi_netdev; > + struct net_device *ndev; > + struct device *dev = &mhi_dev->dev; > + 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); > + > + /* 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); > + > + /* Start MHI channels */ > + err = mhi_prepare_for_transfer(mhi_dev); > + if (err) > + goto out_err; > + > + err = register_netdev(ndev); > + if (err) { > + mhi_unprepare_from_transfer(mhi_dev); > + 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"); > -- > 2.7.4 >
On 10/15/20 12:31 PM, Loic Poulain wrote: > This patch adds a new network driver implementing MHI transport for > network packets. Packets can be in any format, though QMAP (rmnet) > is the usual protocol (flow control + PDN mux). > > It support two MHI devices, IP_HW0 which is, the path to the IPA > (IP accelerator) on qcom modem, And IP_SW0 which is the software > driven IP path (to modem CPU). > > > +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; > + > + skb_tx_timestamp(skb); > + > + /* mhi_queue_skb is not thread-safe, but xmit is serialized by the > + * network core. Once MHI core will be thread save, migrate to > + * NETIF_F_LLTX support. > + */ > + err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT); > + if (err == -ENOMEM) { > + netif_stop_queue(ndev); If you return NETDEV_TX_BUSY, this means this skb will be requeues, then sent again right away, and this will potentially loop forever. Also skb_tx_timestamp() would be called multiple times. I suggest you drop the packet instead. > + return NETDEV_TX_BUSY; > + } else if (unlikely(err)) { > + net_err_ratelimited("%s: Failed to queue TX buf (%d)\n", > + ndev->name, err); > + mhi_netdev->stats.tx_dropped++; > + kfree_skb(skb); > + } > + > + 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); > + > + stats->rx_packets = mhi_netdev->stats.rx_packets; > + stats->rx_bytes = mhi_netdev->stats.rx_bytes; > + stats->rx_errors = mhi_netdev->stats.rx_errors; > + stats->rx_dropped = mhi_netdev->stats.rx_dropped; > + stats->tx_packets = mhi_netdev->stats.tx_packets; > + stats->tx_bytes = mhi_netdev->stats.tx_bytes; > + stats->tx_errors = mhi_netdev->stats.tx_errors; > + stats->tx_dropped = mhi_netdev->stats.tx_dropped; > +} This code is not correct on a 32bit kernel, since u64 values can not be safely be read without extra care.
On Thu, 15 Oct 2020 at 14:41, Eric Dumazet <eric.dumazet@gmail.com> wrote: > > > > On 10/15/20 12:31 PM, Loic Poulain wrote: > > This patch adds a new network driver implementing MHI transport for > > network packets. Packets can be in any format, though QMAP (rmnet) > > is the usual protocol (flow control + PDN mux). > > > > It support two MHI devices, IP_HW0 which is, the path to the IPA > > (IP accelerator) on qcom modem, And IP_SW0 which is the software > > driven IP path (to modem CPU). > > > > > > +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; > > + > > + skb_tx_timestamp(skb); > > + > > + /* mhi_queue_skb is not thread-safe, but xmit is serialized by the > > + * network core. Once MHI core will be thread save, migrate to > > + * NETIF_F_LLTX support. > > + */ > > + err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT); > > + if (err == -ENOMEM) { > > + netif_stop_queue(ndev); > > If you return NETDEV_TX_BUSY, this means this skb will be requeues, > then sent again right away, and this will potentially loop forever. The TX queue is stopped in that case, so the net core will not loop, right? > > Also skb_tx_timestamp() would be called multiple times. OK so I'm going to remove that, maybe the MHI layer should mark timestamp instead. > > I suggest you drop the packet instead. > > > + return NETDEV_TX_BUSY; > > + } else if (unlikely(err)) { > > + net_err_ratelimited("%s: Failed to queue TX buf (%d)\n", > > + ndev->name, err); > > + mhi_netdev->stats.tx_dropped++; > > + kfree_skb(skb); > > + } > > + > > + 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); > > + > > + stats->rx_packets = mhi_netdev->stats.rx_packets; > > + stats->rx_bytes = mhi_netdev->stats.rx_bytes; > > + stats->rx_errors = mhi_netdev->stats.rx_errors; > > + stats->rx_dropped = mhi_netdev->stats.rx_dropped; > > + stats->tx_packets = mhi_netdev->stats.tx_packets; > > + stats->tx_bytes = mhi_netdev->stats.tx_bytes; > > + stats->tx_errors = mhi_netdev->stats.tx_errors; > > + stats->tx_dropped = mhi_netdev->stats.tx_dropped; > > +} > > This code is not correct on a 32bit kernel, since u64 values > can not be safely be read without extra care. > >
On 10/15/20 3:29 PM, Loic Poulain wrote: > On Thu, 15 Oct 2020 at 14:41, Eric Dumazet <eric.dumazet@gmail.com> wrote: >> >> >> >> On 10/15/20 12:31 PM, Loic Poulain wrote: >>> This patch adds a new network driver implementing MHI transport for >>> network packets. Packets can be in any format, though QMAP (rmnet) >>> is the usual protocol (flow control + PDN mux). >>> >>> It support two MHI devices, IP_HW0 which is, the path to the IPA >>> (IP accelerator) on qcom modem, And IP_SW0 which is the software >>> driven IP path (to modem CPU). >>> >>> >>> +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; >>> + >>> + skb_tx_timestamp(skb); >>> + >>> + /* mhi_queue_skb is not thread-safe, but xmit is serialized by the >>> + * network core. Once MHI core will be thread save, migrate to >>> + * NETIF_F_LLTX support. >>> + */ >>> + err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT); >>> + if (err == -ENOMEM) { >>> + netif_stop_queue(ndev); >> >> If you return NETDEV_TX_BUSY, this means this skb will be requeues, >> then sent again right away, and this will potentially loop forever. > > The TX queue is stopped in that case, so the net core will not loop, right? -ENOMEM suggests a memory allocation failed. What is going to restart the queue when memory is available ? -ENOMEM seems weird if used for queue being full. > >> >> Also skb_tx_timestamp() would be called multiple times. > > OK so I'm going to remove that, maybe the MHI layer should mark > timestamp instead. Yes, probably.
Hi Eric, On Thu, 15 Oct 2020 at 20:56, Eric Dumazet <eric.dumazet@gmail.com> wrote: > > > > On 10/15/20 3:29 PM, Loic Poulain wrote: > > On Thu, 15 Oct 2020 at 14:41, Eric Dumazet <eric.dumazet@gmail.com> wrote: > >> > >> > >> > >> On 10/15/20 12:31 PM, Loic Poulain wrote: > >>> This patch adds a new network driver implementing MHI transport for > >>> network packets. Packets can be in any format, though QMAP (rmnet) > >>> is the usual protocol (flow control + PDN mux). > >>> > >>> It support two MHI devices, IP_HW0 which is, the path to the IPA > >>> (IP accelerator) on qcom modem, And IP_SW0 which is the software > >>> driven IP path (to modem CPU). > >>> > >>> > >>> +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; > >>> + > >>> + skb_tx_timestamp(skb); > >>> + > >>> + /* mhi_queue_skb is not thread-safe, but xmit is serialized by the > >>> + * network core. Once MHI core will be thread save, migrate to > >>> + * NETIF_F_LLTX support. > >>> + */ > >>> + err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT); > >>> + if (err == -ENOMEM) { > >>> + netif_stop_queue(ndev); > >> > >> If you return NETDEV_TX_BUSY, this means this skb will be requeues, > >> then sent again right away, and this will potentially loop forever. > > > > The TX queue is stopped in that case, so the net core will not loop, right? > > -ENOMEM suggests a memory allocation failed. > > What is going to restart the queue when memory is available ? The queue is restarted as soon as new ring elements are available, in the tx complete callback (mhi_net_ul_callback). > > -ENOMEM seems weird if used for queue being full. Regarding MHI core, that means no element is available in the ring to push the buffer, so maybe -ENOSPC would be more suitable? This change could be done in a subsequent series since it would request to modify MHI core and other MHI drivers. I'm not sure this is the right way, but this 'stop-queue and return busy' is a pattern used in various other network drivers. However, I understand that a better solution would be to stop the queue earlier, as soon as ring is full and prevent this abnormal situation. > > > > >> > >> Also skb_tx_timestamp() would be called multiple times. > > > > OK so I'm going to remove that, maybe the MHI layer should mark > > timestamp instead. > > Yes, probably. >
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig index 1368d1d..11a6357 100644 --- a/drivers/net/Kconfig +++ b/drivers/net/Kconfig @@ -426,6 +426,13 @@ config VSOCKMON mostly intended for developers or support to debug vsock issues. If unsure, say N. +config MHI_NET + tristate "MHI network driver" + depends on MHI_BUS + help + This is the network driver for MHI. It can be used with + QCOM based WWAN modems (like SDX55). Say Y or M. + endif # NET_CORE config SUNGEM_PHY diff --git a/drivers/net/Makefile b/drivers/net/Makefile index 94b6080..8312037 100644 --- a/drivers/net/Makefile +++ b/drivers/net/Makefile @@ -34,6 +34,7 @@ obj-$(CONFIG_GTP) += gtp.o obj-$(CONFIG_NLMON) += nlmon.o obj-$(CONFIG_NET_VRF) += vrf.o obj-$(CONFIG_VSOCKMON) += vsockmon.o +obj-$(CONFIG_MHI_NET) += mhi_net.o # # Networking Drivers diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c new file mode 100644 index 0000000..fe605a4 --- /dev/null +++ b/drivers/net/mhi_net.c @@ -0,0 +1,289 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* MHI Network driver - Network over MHI + * + * 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> + +#define MIN_MTU ETH_MIN_MTU +#define MAX_MTU 0xffff +#define DEFAULT_MTU 8192 + +struct mhi_net_stats { + u64 rx_packets; + u64 rx_bytes; + u64 rx_errors; + u64 rx_dropped; + u64 tx_packets; + u64 tx_bytes; + u64 tx_errors; + u64 tx_dropped; + atomic_t rx_queued; +}; + +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; + + skb_tx_timestamp(skb); + + /* mhi_queue_skb is not thread-safe, but xmit is serialized by the + * network core. Once MHI core will be thread save, migrate to + * NETIF_F_LLTX support. + */ + err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT); + if (err == -ENOMEM) { + netif_stop_queue(ndev); + return NETDEV_TX_BUSY; + } else if (unlikely(err)) { + net_err_ratelimited("%s: Failed to queue TX buf (%d)\n", + ndev->name, err); + mhi_netdev->stats.tx_dropped++; + kfree_skb(skb); + } + + 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); + + stats->rx_packets = mhi_netdev->stats.rx_packets; + stats->rx_bytes = mhi_netdev->stats.rx_bytes; + stats->rx_errors = mhi_netdev->stats.rx_errors; + stats->rx_dropped = mhi_netdev->stats.rx_dropped; + stats->tx_packets = mhi_netdev->stats.tx_packets; + stats->tx_bytes = mhi_netdev->stats.tx_bytes; + stats->tx_errors = mhi_netdev->stats.tx_errors; + stats->tx_dropped = mhi_netdev->stats.tx_dropped; +} + +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_NONE; /* QMAP... */ + ndev->hard_header_len = 0; + ndev->addr_len = 0; + ndev->flags = IFF_POINTOPOINT | IFF_NOARP; + ndev->netdev_ops = &mhi_netdev_ops; + ndev->mtu = DEFAULT_MTU; + ndev->min_mtu = MIN_MTU; + ndev->max_mtu = 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)) { + mhi_netdev->stats.rx_errors++; + kfree_skb(skb); + } else { + mhi_netdev->stats.rx_packets++; + mhi_netdev->stats.rx_bytes += mhi_res->bytes_xferd; + + skb->protocol = htons(ETH_P_MAP); + 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 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. + */ + consume_skb(skb); + + if (unlikely(mhi_res->transaction_status)) { + mhi_netdev->stats.tx_errors++; + } else { + mhi_netdev->stats.tx_packets++; + mhi_netdev->stats.tx_bytes += mhi_res->bytes_xferd; + } + + if (netif_queue_stopped(ndev)) + 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; + + do { + skb = netdev_alloc_skb(ndev, size); + if (unlikely(!skb)) + break; + + err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb, size, MHI_EOT); + if (err) { + if (unlikely(err != -ENOMEM)) + 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 completed faster than + * queued (unlikely). + */ + cond_resched(); + } while (1); + + /* If we're still starved of rx buffers, reschedule latter */ + if (unlikely(!atomic_read(&mhi_netdev->stats.rx_queued))) + schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2); +} + +static int mhi_net_probe(struct mhi_device *mhi_dev, + const struct mhi_device_id *id) +{ + const char *netname = (char *)id->driver_data; + struct mhi_net_dev *mhi_netdev; + struct net_device *ndev; + struct device *dev = &mhi_dev->dev; + 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); + + /* 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); + + /* Start MHI channels */ + err = mhi_prepare_for_transfer(mhi_dev); + if (err) + goto out_err; + + err = register_netdev(ndev); + if (err) { + mhi_unprepare_from_transfer(mhi_dev); + 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");
This patch adds a new network driver implementing MHI transport for network packets. Packets can be in any format, though QMAP (rmnet) is the usual protocol (flow control + PDN mux). It support two MHI devices, IP_HW0 which is, the path to the IPA (IP accelerator) on qcom modem, And IP_SW0 which is the software driven IP path (to modem CPU). Signed-off-by: Loic Poulain <loic.poulain@linaro.org> --- v2: - rebase on net-next - remove useless skb_linearize - check error type on mhi_queue return - rate limited errors - Schedule RX refill only on 'low' buf level - SET_NETDEV_DEV in probe - reorder device remove sequence v3: - Stop channels on net_register error - Remove useles parentheses - Add driver .owner v4: - prevent potential cpu hog in rx-refill loop - Access mtu via READ_ONCE drivers/net/Kconfig | 7 ++ drivers/net/Makefile | 1 + drivers/net/mhi_net.c | 289 ++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 297 insertions(+) create mode 100644 drivers/net/mhi_net.c