Date:   Thu, 20 May 2021 19:31:57 +0530
From:   M Chetan Kumar <m.chetan.kumar@...el.com>
To:     netdev@...r.kernel.org, linux-wireless@...r.kernel.org
Cc:     johannes@...solutions.net, krishna.c.sudi@...el.com,
        linuxwwan@...el.com
Subject: [PATCH V3 15/16] net: iosm: net driver

1) Create net device & implement net operations for data/IP communication.
2) Bind IP Link to mux IP session for simultaneous IP traffic.

Signed-off-by: M Chetan Kumar <m.chetan.kumar@...el.com>
---
v3:
* Clean-up DSS channel implementation.
* Aligned ipc_ prefix for function name to be consistent across file.
v2:
* Removed Ethernet header & VLAN tag handling from wwan net driver.
* Implement rtnet_link interface for IP traffic handling.
---
 drivers/net/wwan/iosm/iosm_ipc_wwan.c | 439 ++++++++++++++++++++++++++
 drivers/net/wwan/iosm/iosm_ipc_wwan.h |  55 ++++
 2 files changed, 494 insertions(+)
 create mode 100644 drivers/net/wwan/iosm/iosm_ipc_wwan.c
 create mode 100644 drivers/net/wwan/iosm/iosm_ipc_wwan.h

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..02c35bc86674
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_wwan.c
@@ -0,0 +1,439 @@
+// 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 <net/rtnetlink.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
+
+static struct device_type wwan_type = { .name = "wwan" };
+
+static const struct nla_policy ipc_wwan_policy[IFLA_IOSM_MAX + 1] = {
+	[IFLA_IOSM_IF_ID]	= { .type = NLA_U16 },
+};
+
+/**
+ * struct iosm_net_link - This structure includes information about interface
+ *			  dev.
+ * @if_id:	Interface id for device.
+ * @ch_id:	IPC channel number for which interface device is created.
+ * @netdev:	Pointer to network interface device structure
+ * @ipc_wwan:	Pointer to iosm_wwan struct
+ */
+
+struct iosm_net_link {
+	int if_id;
+	int ch_id;
+	struct net_device *netdev;
+	struct iosm_wwan *ipc_wwan;
+};
+
+/**
+ * struct iosm_wwan - This structure contains information about WWAN root device
+ *		     and interface to the IPC layer.
+ * @netdev:		Pointer to network interface device structure.
+ * @sub_netlist:	List of netlink interfaces
+ * @ipc_imem:		Pointer to imem data-struct
+ * @dev:		Pointer device structure
+ * @if_mutex:		Mutex used for add and remove interface id
+ * @is_registered:	Registration status with netdev
+ */
+struct iosm_wwan {
+	struct net_device *netdev;
+	struct iosm_net_link __rcu *sub_netlist[MAX_IP_MUX_SESSION];
+	struct iosm_imem *ipc_imem;
+	struct device *dev;
+	struct mutex if_mutex; /* Mutex used for add and remove interface id */
+	u8 is_registered:1;
+};
+
+/* Bring-up the wwan net link */
+static int ipc_wwan_link_open(struct net_device *netdev)
+{
+	struct iosm_net_link *netlink = netdev_priv(netdev);
+	struct iosm_wwan *ipc_wwan = netlink->ipc_wwan;
+	int if_id = netlink->if_id;
+	int ret = -EINVAL;
+
+	if (if_id < IP_MUX_SESSION_START || if_id > IP_MUX_SESSION_END)
+		return ret;
+
+	mutex_lock(&ipc_wwan->if_mutex);
+
+	/* get channel id */
+	netlink->ch_id =
+		ipc_imem_sys_wwan_open(ipc_wwan->ipc_imem, if_id);
+
+	if (netlink->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",
+		netlink->ch_id, netlink->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_net_link *netlink = netdev_priv(netdev);
+
+	netif_stop_queue(netdev);
+
+	mutex_lock(&netlink->ipc_wwan->if_mutex);
+	ipc_imem_sys_wwan_close(netlink->ipc_wwan->ipc_imem, netlink->if_id,
+				netlink->ch_id);
+	mutex_unlock(&netlink->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_net_link *netlink = netdev_priv(netdev);
+	struct iosm_wwan *ipc_wwan = netlink->ipc_wwan;
+	int if_id = netlink->if_id;
+	int ret = -EINVAL;
+
+	/* 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 > IP_MUX_SESSION_END)
+		goto exit;
+
+	/* Send the SKB to device for transmission */
+	ret = ipc_imem_sys_wwan_transmit(ipc_wwan->ipc_imem,
+					 if_id, netlink->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;
+}
+
+static struct device_type inm_type = { .name = "iosmdev" };
+
+/* Create new wwan net link */
+static int ipc_wwan_newlink(struct net *src_net, struct net_device *dev,
+			    struct nlattr *tb[], struct nlattr *data[],
+			    struct netlink_ext_ack *extack)
+{
+	struct iosm_net_link *netlink = netdev_priv(dev);
+	struct iosm_wwan *ipc_wwan;
+	struct net_device *netdev;
+	int err = -EINVAL;
+	int index;
+
+	if (!data[IFLA_IOSM_IF_ID]) {
+		pr_err("Interface ID not specified");
+		goto out;
+	}
+
+	if (!tb[IFLA_LINK]) {
+		pr_err("Link not specified");
+		goto out;
+	}
+
+	netlink->netdev = dev;
+
+	netdev = __dev_get_by_index(src_net, nla_get_u32(tb[IFLA_LINK]));
+
+	netlink->ipc_wwan = netdev_priv(netdev);
+
+	ipc_wwan = netlink->ipc_wwan;
+
+	if (ipc_wwan->netdev != netdev)
+		goto out;
+
+	netlink->if_id = nla_get_u16(data[IFLA_IOSM_IF_ID]);
+	index = netlink->if_id;
+
+	/* Complete all memory stores before this point */
+	smp_mb();
+	if (index < IP_MUX_SESSION_START || index > IP_MUX_SESSION_END)
+		goto out;
+
+	rcu_read_lock();
+
+	if (rcu_access_pointer(ipc_wwan->sub_netlist[index - 1])) {
+		pr_err("IOSM interface ID already in use");
+		goto out_free_lock;
+	}
+
+	SET_NETDEV_DEVTYPE(dev, &inm_type);
+
+	eth_hw_addr_random(dev);
+	err = register_netdevice(dev);
+	if (err) {
+		dev_err(ipc_wwan->dev, "register netlink failed.\n");
+		goto out_free_lock;
+	}
+
+	err = netdev_upper_dev_link(ipc_wwan->netdev, dev, extack);
+
+	if (err) {
+		dev_err(ipc_wwan->dev, "netdev linking with parent failed.\n");
+		goto netlink_err;
+	}
+
+	rcu_assign_pointer(ipc_wwan->sub_netlist[index - 1], netlink);
+	netif_device_attach(dev);
+	rcu_read_unlock();
+
+	return 0;
+
+netlink_err:
+	unregister_netdevice(dev);
+out_free_lock:
+	rcu_read_unlock();
+out:
+	return err;
+}
+
+/* Delete new wwan net link */
+static void ipc_wwan_dellink(struct net_device *dev, struct list_head *head)
+{
+	struct iosm_net_link *netlink = netdev_priv(dev);
+	u16 index = netlink->if_id;
+
+	netdev_upper_dev_unlink(netlink->ipc_wwan->netdev, dev);
+	unregister_netdevice(dev);
+
+	mutex_lock(&netlink->ipc_wwan->if_mutex);
+	rcu_assign_pointer(netlink->ipc_wwan->sub_netlist[index - 1], NULL);
+	mutex_unlock(&netlink->ipc_wwan->if_mutex);
+}
+
+/* Get size for iosm net link payload*/
+static size_t ipc_wwan_get_size(const struct net_device *dev)
+{
+	return nla_total_size(IOSM_IF_ID_PAYLOAD);
+}
+
+/* Validate the input parameters for wwan net link */
+static int ipc_wwan_validate(struct nlattr *tb[], struct nlattr *data[],
+			     struct netlink_ext_ack *extack)
+{
+	u16 if_id;
+
+	if (!data || !data[IFLA_IOSM_IF_ID]) {
+		NL_SET_ERR_MSG_MOD(extack, "IF ID not specified");
+		return -EINVAL;
+	}
+
+	if_id = nla_get_u16(data[IFLA_IOSM_IF_ID]);
+
+	if (if_id < IP_MUX_SESSION_START || if_id > IP_MUX_SESSION_END) {
+		NL_SET_ERR_MSG_MOD(extack, "Invalid Interface");
+		return -ERANGE;
+	}
+
+	return 0;
+}
+
+/* RT Net link ops structure for new wwan net link */
+struct rtnl_link_ops iosm_netlink __read_mostly = {
+	.kind           = "iosm",
+	.maxtype        = __IFLA_IOSM_MAX,
+	.priv_size      = sizeof(struct iosm_net_link),
+	.setup          = ipc_wwan_setup,
+	.validate       = ipc_wwan_validate,
+	.newlink        = ipc_wwan_newlink,
+	.dellink        = ipc_wwan_dellink,
+	.get_size       = ipc_wwan_get_size,
+	.policy         = ipc_wwan_policy,
+};
+
+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;
+	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)) {
+		dev_kfree_skb(skb);
+		return -EINVAL;
+	}
+
+	rcu_read_lock();
+	skb->dev = rcu_dereference(ipc_wwan->sub_netlist[if_id])->netdev;
+	stats = rcu_dereference(ipc_wwan->sub_netlist[if_id])->netdev->stats;
+	stats.rx_packets++;
+	stats.rx_bytes += skb->len;
+
+	ret = netif_rx(skb);
+	rcu_read_unlock();
+
+	return ret;
+}
+
+void ipc_wwan_tx_flowctrl(struct iosm_wwan *ipc_wwan, int if_id, bool on)
+{
+	struct net_device *netdev;
+	bool is_tx_blk;
+
+	rcu_read_lock();
+	netdev = rcu_dereference(ipc_wwan->sub_netlist[if_id])->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();
+}
+
+static void ipc_netdev_setup(struct net_device *dev) {}
+
+struct iosm_wwan *ipc_wwan_init(struct iosm_imem *ipc_imem, struct device *dev)
+{
+	static const struct net_device_ops iosm_wwandev_ops = {};
+	struct iosm_wwan *ipc_wwan;
+	struct net_device *netdev;
+
+	netdev = alloc_netdev(sizeof(*ipc_wwan), "wwan%d", NET_NAME_ENUM,
+			      ipc_netdev_setup);
+
+	if (!netdev)
+		return NULL;
+
+	ipc_wwan = netdev_priv(netdev);
+
+	ipc_wwan->dev = dev;
+	ipc_wwan->netdev = netdev;
+	ipc_wwan->is_registered = false;
+
+	ipc_wwan->ipc_imem = ipc_imem;
+
+	mutex_init(&ipc_wwan->if_mutex);
+
+	/* allocate random ethernet address */
+	eth_random_addr(netdev->dev_addr);
+	netdev->addr_assign_type = NET_ADDR_RANDOM;
+
+	netdev->netdev_ops = &iosm_wwandev_ops;
+	netdev->flags |= IFF_NOARP;
+
+	SET_NETDEV_DEVTYPE(netdev, &wwan_type);
+
+	if (register_netdev(netdev)) {
+		dev_err(ipc_wwan->dev, "register_netdev failed");
+		goto reg_fail;
+	}
+
+	ipc_wwan->is_registered = true;
+
+	netif_device_attach(netdev);
+
+	return ipc_wwan;
+
+reg_fail:
+	free_netdev(netdev);
+	return NULL;
+}
+
+void ipc_wwan_deinit(struct iosm_wwan *ipc_wwan)
+{
+	struct iosm_net_link *netlink;
+	int i;
+
+	if (ipc_wwan->is_registered) {
+		rcu_read_lock();
+		for (i = IP_MUX_SESSION_START; i <= IP_MUX_SESSION_END; i++) {
+			if (rcu_access_pointer(ipc_wwan->sub_netlist[i - 1])) {
+				netlink =
+				rcu_dereference(ipc_wwan->sub_netlist[i - 1]);
+				rtnl_lock();
+				netdev_upper_dev_unlink(ipc_wwan->netdev,
+							netlink->netdev);
+				unregister_netdevice(netlink->netdev);
+				rtnl_unlock();
+				rcu_assign_pointer(ipc_wwan->sub_netlist[i - 1],
+						   NULL);
+			}
+		}
+		rcu_read_unlock();
+
+		unregister_netdev(ipc_wwan->netdev);
+		free_netdev(ipc_wwan->netdev);
+	}
+}
diff --git a/drivers/net/wwan/iosm/iosm_ipc_wwan.h b/drivers/net/wwan/iosm/iosm_ipc_wwan.h
new file mode 100644
index 000000000000..4925f22dff0a
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_wwan.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0-only
+ *
+ * Copyright (C) 2020-21 Intel Corporation.
+ */
+
+#ifndef IOSM_IPC_WWAN_H
+#define IOSM_IPC_WWAN_H
+
+/**
+ * ipc_wwan_init - Allocate, Init and register WWAN device
+ * @ipc_imem:		Pointer to imem data-struct
+ * @dev:		Pointer to device structure
+ *
+ * Returns: Pointer to instance on success else NULL
+ */
+struct iosm_wwan *ipc_wwan_init(struct iosm_imem *ipc_imem, struct device *dev);
+
+/**
+ * ipc_wwan_deinit - Unregister and free WWAN device, clear pointer
+ * @ipc_wwan:	Pointer to wwan instance data
+ */
+void ipc_wwan_deinit(struct iosm_wwan *ipc_wwan);
+
+/**
+ * ipc_wwan_receive - Receive a downlink packet from CP.
+ * @ipc_wwan:	Pointer to wwan instance
+ * @skb_arg:	Pointer to struct sk_buff
+ * @dss:	Set to true if interafce id is from 257 to 261,
+ *		else false
+ * @if_id:	Interface ID
+ *
+ * Return: 0 on success and failure value on error
+ */
+int ipc_wwan_receive(struct iosm_wwan *ipc_wwan, struct sk_buff *skb_arg,
+		     bool dss, int if_id);
+
+/**
+ * ipc_wwan_tx_flowctrl - Enable/Disable TX flow control
+ * @ipc_wwan:	Pointer to wwan instance
+ * @id:		Ipc mux channel session id
+ * @on:		if true then flow ctrl would be enabled else disable
+ *
+ */
+void ipc_wwan_tx_flowctrl(struct iosm_wwan *ipc_wwan, int id, bool on);
+
+/**
+ * ipc_wwan_is_tx_stopped - Checks if Tx stopped for a Interface id.
+ * @ipc_wwan:	Pointer to wwan instance
+ * @id:		Ipc mux channel session id
+ *
+ * Return: true if stopped, false otherwise
+ */
+bool ipc_wwan_is_tx_stopped(struct iosm_wwan *ipc_wwan, int id);
+
+#endif
-- 
2.25.1

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