Merge branch 'iosm-driver'

M Chetan Kumar says:

====================
net: iosm: PCIe Driver for Intel M.2 Modem

The IOSM (IPC over Shared Memory) driver is a PCIe host driver implemented
for linux or chrome platform for data exchange over PCIe interface between
Host platform & Intel M.2 Modem. The driver exposes interface conforming to
the MBIM protocol. Any front end application ( eg: Modem Manager) could
easily manage the MBIM interface to enable data communication towards WWAN.

Intel M.2 modem uses 2 BAR regions. The first region is dedicated to Doorbell
register for IRQs and the second region is used as scratchpad area for book
keeping modem execution stage details along with host system shared memory
region context details. The upper edge of the driver exposes the control and
data channels for user space application interaction. At lower edge these data
and control channels are associated to pipes. The pipes are lowest level
interfaces used over PCIe as a logical channel for message exchange. A single
channel maps to UL and DL pipe and are initialized on device open.

On UL path, driver copies application sent data to SKBs associate it with
transfer descriptor and puts it on to ring buffer for DMA transfer. Once
information has been updated in shared memory region, host gives a Doorbell
to modem to perform DMA and modem uses MSI to communicate back to host.
For receiving data in DL path, SKBs are pre-allocated during pipe open and
transfer descriptors are given to modem for DMA transfer.

The driver exposes two types of ports, namely "wwan0mbim0", a char device node
which is used for MBIM control operation and "wwan0-x",(x = 0,1,2..7) network
interfaces for IP data communication.
1) MBIM Control Interface:
This node exposes an interface between modem and application using char device
exposed by "IOSM" driver to establish and manage the MBIM data communication
with PCIe based Intel M.2 Modems.

2) MBIM Data Interface:
The IOSM driver exposes IP link interface "wwan0-x" of type "wwan" for IP traffic.
Iproute network utility is used for creating "wwan0-x" network interface and for
associating it with MBIM IP session. The Driver supports upto 8 IP sessions for
simultaneous IP communication.

This applies on top of WWAN core rtnetlink series posted here:
https://lore.kernel.org/netdev/1623486057-13075-1-git-send-email-loic.poulain@linaro.org/

Also driver has been compiled and tested on top of netdev net-next tree.
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 351 insertions, 0 deletions

diff --git a/drivers/net/wwan/iosm/iosm_ipc_wwan.c b/drivers/net/wwan/iosm/iosm_ipc_wwan.c
new file mode 100644
index 000000000000..1711b79fc616
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_wwan.c
@@ -0,0 +1,351 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020-21 Intel Corporation.
+ */
+
+#include <linux/etherdevice.h>
+#include <linux/if_arp.h>
+#include <linux/if_link.h>
+#include <linux/rtnetlink.h>
+#include <linux/wwan.h>
+
+#include "iosm_ipc_chnl_cfg.h"
+#include "iosm_ipc_imem_ops.h"
+#include "iosm_ipc_wwan.h"
+
+#define IOSM_IP_TYPE_MASK 0xF0
+#define IOSM_IP_TYPE_IPV4 0x40
+#define IOSM_IP_TYPE_IPV6 0x60
+
+#define IOSM_IF_ID_PAYLOAD 2
+
+/**
+ * struct iosm_netdev_priv - netdev private data
+ * @ipc_wwan:	Pointer to iosm_wwan struct
+ * @netdev:	Pointer to network interface device structure
+ * @if_id:	Interface id for device.
+ * @ch_id:	IPC channel number for which interface device is created.
+ */
+struct iosm_netdev_priv {
+	struct iosm_wwan *ipc_wwan;
+	struct net_device *netdev;
+	int if_id;
+	int ch_id;
+};
+
+/**
+ * struct iosm_wwan - This structure contains information about WWAN root device
+ *		      and interface to the IPC layer.
+ * @ipc_imem:		Pointer to imem data-struct
+ * @sub_netlist:	List of active netdevs
+ * @dev:		Pointer device structure
+ * @if_mutex:		Mutex used for add and remove interface id
+ */
+struct iosm_wwan {
+	struct iosm_imem *ipc_imem;
+	struct iosm_netdev_priv __rcu *sub_netlist[IP_MUX_SESSION_END + 1];
+	struct device *dev;
+	struct mutex if_mutex; /* Mutex used for add and remove interface id */
+};
+
+/* Bring-up the wwan net link */
+static int ipc_wwan_link_open(struct net_device *netdev)
+{
+	struct iosm_netdev_priv *priv = netdev_priv(netdev);
+	struct iosm_wwan *ipc_wwan = priv->ipc_wwan;
+	int if_id = priv->if_id;
+	int ret;
+
+	if (if_id < IP_MUX_SESSION_START ||
+	    if_id >= ARRAY_SIZE(ipc_wwan->sub_netlist))
+		return -EINVAL;
+
+	mutex_lock(&ipc_wwan->if_mutex);
+
+	/* get channel id */
+	priv->ch_id = ipc_imem_sys_wwan_open(ipc_wwan->ipc_imem, if_id);
+
+	if (priv->ch_id < 0) {
+		dev_err(ipc_wwan->dev,
+			"cannot connect wwan0 & id %d to the IPC mem layer",
+			if_id);
+		ret = -ENODEV;
+		goto out;
+	}
+
+	/* enable tx path, DL data may follow */
+	netif_start_queue(netdev);
+
+	dev_dbg(ipc_wwan->dev, "Channel id %d allocated to if_id %d",
+		priv->ch_id, priv->if_id);
+
+	ret = 0;
+out:
+	mutex_unlock(&ipc_wwan->if_mutex);
+	return ret;
+}
+
+/* Bring-down the wwan net link */
+static int ipc_wwan_link_stop(struct net_device *netdev)
+{
+	struct iosm_netdev_priv *priv = netdev_priv(netdev);
+
+	netif_stop_queue(netdev);
+
+	mutex_lock(&priv->ipc_wwan->if_mutex);
+	ipc_imem_sys_wwan_close(priv->ipc_wwan->ipc_imem, priv->if_id,
+				priv->ch_id);
+	priv->ch_id = -1;
+	mutex_unlock(&priv->ipc_wwan->if_mutex);
+
+	return 0;
+}
+
+/* Transmit a packet */
+static int ipc_wwan_link_transmit(struct sk_buff *skb,
+				  struct net_device *netdev)
+{
+	struct iosm_netdev_priv *priv = netdev_priv(netdev);
+	struct iosm_wwan *ipc_wwan = priv->ipc_wwan;
+	int if_id = priv->if_id;
+	int ret;
+
+	/* Interface IDs from 1 to 8 are for IP data
+	 * & from 257 to 261 are for non-IP data
+	 */
+	if (if_id < IP_MUX_SESSION_START ||
+	    if_id >= ARRAY_SIZE(ipc_wwan->sub_netlist))
+		return -EINVAL;
+
+	/* Send the SKB to device for transmission */
+	ret = ipc_imem_sys_wwan_transmit(ipc_wwan->ipc_imem,
+					 if_id, priv->ch_id, skb);
+
+	/* Return code of zero is success */
+	if (ret == 0) {
+		ret = NETDEV_TX_OK;
+	} else if (ret == -EBUSY) {
+		ret = NETDEV_TX_BUSY;
+		dev_err(ipc_wwan->dev, "unable to push packets");
+	} else {
+		goto exit;
+	}
+
+	return ret;
+
+exit:
+	/* Log any skb drop */
+	if (if_id)
+		dev_dbg(ipc_wwan->dev, "skb dropped. IF_ID: %d, ret: %d", if_id,
+			ret);
+
+	dev_kfree_skb_any(skb);
+	return ret;
+}
+
+/* Ops structure for wwan net link */
+static const struct net_device_ops ipc_inm_ops = {
+	.ndo_open = ipc_wwan_link_open,
+	.ndo_stop = ipc_wwan_link_stop,
+	.ndo_start_xmit = ipc_wwan_link_transmit,
+};
+
+/* Setup function for creating new net link */
+static void ipc_wwan_setup(struct net_device *iosm_dev)
+{
+	iosm_dev->header_ops = NULL;
+	iosm_dev->hard_header_len = 0;
+	iosm_dev->priv_flags |= IFF_NO_QUEUE;
+
+	iosm_dev->type = ARPHRD_NONE;
+	iosm_dev->min_mtu = ETH_MIN_MTU;
+	iosm_dev->max_mtu = ETH_MAX_MTU;
+
+	iosm_dev->flags = IFF_POINTOPOINT | IFF_NOARP;
+
+	iosm_dev->netdev_ops = &ipc_inm_ops;
+}
+
+/* Create new wwan net link */
+static int ipc_wwan_newlink(void *ctxt, struct net_device *dev,
+			    u32 if_id, struct netlink_ext_ack *extack)
+{
+	struct iosm_wwan *ipc_wwan = ctxt;
+	struct iosm_netdev_priv *priv;
+	int err;
+
+	if (if_id < IP_MUX_SESSION_START ||
+	    if_id >= ARRAY_SIZE(ipc_wwan->sub_netlist))
+		return -EINVAL;
+
+	priv = netdev_priv(dev);
+	priv->if_id = if_id;
+	priv->netdev = dev;
+	priv->ipc_wwan = ipc_wwan;
+
+	mutex_lock(&ipc_wwan->if_mutex);
+	if (rcu_access_pointer(ipc_wwan->sub_netlist[if_id])) {
+		err = -EBUSY;
+		goto out_unlock;
+	}
+
+	err = register_netdevice(dev);
+	if (err)
+		goto out_unlock;
+
+	rcu_assign_pointer(ipc_wwan->sub_netlist[if_id], priv);
+	mutex_unlock(&ipc_wwan->if_mutex);
+
+	netif_device_attach(dev);
+
+	return 0;
+
+out_unlock:
+	mutex_unlock(&ipc_wwan->if_mutex);
+	return err;
+}
+
+static void ipc_wwan_dellink(void *ctxt, struct net_device *dev,
+			     struct list_head *head)
+{
+	struct iosm_wwan *ipc_wwan = ctxt;
+	struct iosm_netdev_priv *priv = netdev_priv(dev);
+	int if_id = priv->if_id;
+
+	if (WARN_ON(if_id < IP_MUX_SESSION_START ||
+		    if_id >= ARRAY_SIZE(ipc_wwan->sub_netlist)))
+		return;
+
+	mutex_lock(&ipc_wwan->if_mutex);
+
+	if (WARN_ON(rcu_access_pointer(ipc_wwan->sub_netlist[if_id]) != priv))
+		goto unlock;
+
+	RCU_INIT_POINTER(ipc_wwan->sub_netlist[if_id], NULL);
+	/* unregistering includes synchronize_net() */
+	unregister_netdevice(dev);
+
+unlock:
+	mutex_unlock(&ipc_wwan->if_mutex);
+}
+
+static const struct wwan_ops iosm_wwan_ops = {
+	.priv_size = sizeof(struct iosm_netdev_priv),
+	.setup = ipc_wwan_setup,
+	.newlink = ipc_wwan_newlink,
+	.dellink = ipc_wwan_dellink,
+};
+
+int ipc_wwan_receive(struct iosm_wwan *ipc_wwan, struct sk_buff *skb_arg,
+		     bool dss, int if_id)
+{
+	struct sk_buff *skb = skb_arg;
+	struct net_device_stats *stats;
+	struct iosm_netdev_priv *priv;
+	int ret;
+
+	if ((skb->data[0] & IOSM_IP_TYPE_MASK) == IOSM_IP_TYPE_IPV4)
+		skb->protocol = htons(ETH_P_IP);
+	else if ((skb->data[0] & IOSM_IP_TYPE_MASK) ==
+		 IOSM_IP_TYPE_IPV6)
+		skb->protocol = htons(ETH_P_IPV6);
+
+	skb->pkt_type = PACKET_HOST;
+
+	if (if_id < (IP_MUX_SESSION_START - 1) ||
+	    if_id > (IP_MUX_SESSION_END - 1)) {
+		ret = -EINVAL;
+		goto free;
+	}
+
+	rcu_read_lock();
+	priv = rcu_dereference(ipc_wwan->sub_netlist[if_id]);
+	if (!priv) {
+		ret = -EINVAL;
+		goto unlock;
+	}
+	skb->dev = priv->netdev;
+	stats = &priv->netdev->stats;
+	stats->rx_packets++;
+	stats->rx_bytes += skb->len;
+
+	ret = netif_rx(skb);
+	skb = NULL;
+unlock:
+	rcu_read_unlock();
+free:
+	dev_kfree_skb(skb);
+	return ret;
+}
+
+void ipc_wwan_tx_flowctrl(struct iosm_wwan *ipc_wwan, int if_id, bool on)
+{
+	struct net_device *netdev;
+	struct iosm_netdev_priv *priv;
+	bool is_tx_blk;
+
+	rcu_read_lock();
+	priv = rcu_dereference(ipc_wwan->sub_netlist[if_id]);
+	if (!priv) {
+		rcu_read_unlock();
+		return;
+	}
+
+	netdev = priv->netdev;
+
+	is_tx_blk = netif_queue_stopped(netdev);
+
+	if (on)
+		dev_dbg(ipc_wwan->dev, "session id[%d]: flowctrl enable",
+			if_id);
+
+	if (on && !is_tx_blk)
+		netif_stop_queue(netdev);
+	else if (!on && is_tx_blk)
+		netif_wake_queue(netdev);
+	rcu_read_unlock();
+}
+
+struct iosm_wwan *ipc_wwan_init(struct iosm_imem *ipc_imem, struct device *dev)
+{
+	struct iosm_wwan *ipc_wwan;
+
+	ipc_wwan = kzalloc(sizeof(*ipc_wwan), GFP_KERNEL);
+	if (!ipc_wwan)
+		return NULL;
+
+	ipc_wwan->dev = dev;
+	ipc_wwan->ipc_imem = ipc_imem;
+
+	if (wwan_register_ops(ipc_wwan->dev, &iosm_wwan_ops, ipc_wwan)) {
+		kfree(ipc_wwan);
+		return NULL;
+	}
+
+	mutex_init(&ipc_wwan->if_mutex);
+
+	return ipc_wwan;
+}
+
+void ipc_wwan_deinit(struct iosm_wwan *ipc_wwan)
+{
+	int if_id;
+
+	wwan_unregister_ops(ipc_wwan->dev);
+
+	for (if_id = 0; if_id < ARRAY_SIZE(ipc_wwan->sub_netlist); if_id++) {
+		struct iosm_netdev_priv *priv;
+
+		priv = rcu_access_pointer(ipc_wwan->sub_netlist[if_id]);
+		if (!priv)
+			continue;
+
+		rtnl_lock();
+		ipc_wwan_dellink(ipc_wwan, priv->netdev, NULL);
+		rtnl_unlock();
+	}
+
+	mutex_destroy(&ipc_wwan->if_mutex);
+
+	kfree(ipc_wwan);
+}