wwan: core: add WWAN common private data for netdev

The WWAN core not only multiplex the netdev configuration data, but
process it too, and needs some space to store its private data
associated with the netdev. Add a structure to keep common WWAN core
data. The structure will be stored inside the netdev private data before
WWAN driver private data and have a field to make it easier to access
the driver data. Also add a helper function that simplifies drivers
access to their data.

At the moment we use the common WWAN private data to store the WWAN data
link (channel) id at the time the link is created, and report it back to
user using the .fill_info() RTNL callback. This should help the user to
be aware which network interface is bound to which WWAN device data
channel.

Signed-off-by: Sergey Ryazanov <[e-mail]>
CC: M Chetan Kumar <[e-mail]>
CC: Intel Corporation <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/mhi/net.c

···
 
 static int mhi_ndo_open(struct net_device *ndev)
 {
-	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
+	struct mhi_net_dev *mhi_netdev = wwan_netdev_drvpriv(ndev);
 
 	/* Feed the rx buffer pool */
 	schedule_delayed_work(&mhi_netdev->rx_refill, 0);
···
 
 static int mhi_ndo_stop(struct net_device *ndev)
 {
-	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
+	struct mhi_net_dev *mhi_netdev = wwan_netdev_drvpriv(ndev);
 
 	netif_stop_queue(ndev);
 	netif_carrier_off(ndev);
···
 
 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_net_dev *mhi_netdev = wwan_netdev_drvpriv(ndev);
 	const struct mhi_net_proto *proto = mhi_netdev->proto;
 	struct mhi_device *mdev = mhi_netdev->mdev;
 	int err;
···
 static void mhi_ndo_get_stats64(struct net_device *ndev,
 				struct rtnl_link_stats64 *stats)
 {
-	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
+	struct mhi_net_dev *mhi_netdev = wwan_netdev_drvpriv(ndev);
 	unsigned int start;
 
 	do {
···
 	if (dev_get_drvdata(&mhi_dev->dev))
 		return -EBUSY;
 
-	mhi_netdev = netdev_priv(ndev);
+	mhi_netdev = wwan_netdev_drvpriv(ndev);
 
 	dev_set_drvdata(&mhi_dev->dev, mhi_netdev);
 	mhi_netdev->ndev = ndev;
···
 static void mhi_net_dellink(void *ctxt, struct net_device *ndev,
 			    struct list_head *head)
 {
-	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
+	struct mhi_net_dev *mhi_netdev = wwan_netdev_drvpriv(ndev);
 	struct mhi_device *mhi_dev = ctxt;
 
 	if (head)

drivers/net/mhi/proto_mbim.c

···
 #include <linux/ip.h>
 #include <linux/mii.h>
 #include <linux/netdevice.h>
+#include <linux/wwan.h>
 #include <linux/skbuff.h>
 #include <linux/usb.h>
 #include <linux/usb/cdc.h>
···
 
 static int mbim_rx_verify_nth16(struct sk_buff *skb)
 {
-	struct mhi_net_dev *dev = netdev_priv(skb->dev);
+	struct mhi_net_dev *dev = wwan_netdev_drvpriv(skb->dev);
 	struct mbim_context *ctx = dev->proto_data;
 	struct usb_cdc_ncm_nth16 *nth16;
 	int len;
···
 
 static int mbim_rx_verify_ndp16(struct sk_buff *skb, struct usb_cdc_ncm_ndp16 *ndp16)
 {
-	struct mhi_net_dev *dev = netdev_priv(skb->dev);
+	struct mhi_net_dev *dev = wwan_netdev_drvpriv(skb->dev);
 	int ret;
 
 	if (le16_to_cpu(ndp16->wLength) < USB_CDC_NCM_NDP16_LENGTH_MIN) {

drivers/net/wwan/iosm/iosm_ipc_wwan.c

···
 #define IOSM_IF_ID_PAYLOAD 2
 
 /**
- * struct iosm_netdev_priv - netdev private data
+ * struct iosm_netdev_priv - netdev WWAN driver specific private data
  * @ipc_wwan:	Pointer to iosm_wwan struct
  * @netdev:	Pointer to network interface device structure
  * @if_id:	Interface id for device.
···
 /* 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_netdev_priv *priv = wwan_netdev_drvpriv(netdev);
 	struct iosm_wwan *ipc_wwan = priv->ipc_wwan;
 	int if_id = priv->if_id;
 	int 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);
+	struct iosm_netdev_priv *priv = wwan_netdev_drvpriv(netdev);
 
 	netif_stop_queue(netdev);
 
···
 static int ipc_wwan_link_transmit(struct sk_buff *skb,
 				  struct net_device *netdev)
 {
-	struct iosm_netdev_priv *priv = netdev_priv(netdev);
+	struct iosm_netdev_priv *priv = wwan_netdev_drvpriv(netdev);
 	struct iosm_wwan *ipc_wwan = priv->ipc_wwan;
 	int if_id = priv->if_id;
 	int ret;
···
 	    if_id >= ARRAY_SIZE(ipc_wwan->sub_netlist))
 		return -EINVAL;
 
-	priv = netdev_priv(dev);
+	priv = wwan_netdev_drvpriv(dev);
 	priv->if_id = if_id;
 	priv->netdev = dev;
 	priv->ipc_wwan = ipc_wwan;
···
 static void ipc_wwan_dellink(void *ctxt, struct net_device *dev,
 			     struct list_head *head)
 {
+	struct iosm_netdev_priv *priv = wwan_netdev_drvpriv(dev);
 	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 ||

drivers/net/wwan/wwan_core.c

···
 	const char *devname = nla_data(tb[IFLA_PARENT_DEV_NAME]);
 	struct wwan_device *wwandev = wwan_dev_get_by_name(devname);
 	struct net_device *dev;
+	unsigned int priv_size;
 
 	if (IS_ERR(wwandev))
 		return ERR_CAST(wwandev);
···
 		goto out;
 	}
 
-	dev = alloc_netdev_mqs(wwandev->ops->priv_size, ifname, name_assign_type,
+	priv_size = sizeof(struct wwan_netdev_priv) + wwandev->ops->priv_size;
+	dev = alloc_netdev_mqs(priv_size, ifname, name_assign_type,
 			       wwandev->ops->setup, num_tx_queues, num_rx_queues);
 
 	if (dev) {
···
 {
 	struct wwan_device *wwandev = wwan_dev_get_by_parent(dev->dev.parent);
 	u32 link_id = nla_get_u32(data[IFLA_WWAN_LINK_ID]);
+	struct wwan_netdev_priv *priv = netdev_priv(dev);
 	int ret;
 
 	if (IS_ERR(wwandev))
···
 		goto out;
 	}
 
+	priv->link_id = link_id;
 	if (wwandev->ops->newlink)
 		ret = wwandev->ops->newlink(wwandev->ops_ctxt, dev,
 					    link_id, extack);
···
 	put_device(&wwandev->dev);
 }
 
+static size_t wwan_rtnl_get_size(const struct net_device *dev)
+{
+	return
+		nla_total_size(4) +	/* IFLA_WWAN_LINK_ID */
+		0;
+}
+
+static int wwan_rtnl_fill_info(struct sk_buff *skb,
+			       const struct net_device *dev)
+{
+	struct wwan_netdev_priv *priv = netdev_priv(dev);
+
+	if (nla_put_u32(skb, IFLA_WWAN_LINK_ID, priv->link_id))
+		goto nla_put_failure;
+
+	return 0;
+
+nla_put_failure:
+	return -EMSGSIZE;
+}
+
 static const struct nla_policy wwan_rtnl_policy[IFLA_WWAN_MAX + 1] = {
 	[IFLA_WWAN_LINK_ID] = { .type = NLA_U32 },
 };
···
 	.validate = wwan_rtnl_validate,
 	.newlink = wwan_rtnl_newlink,
 	.dellink = wwan_rtnl_dellink,
+	.get_size = wwan_rtnl_get_size,
+	.fill_info = wwan_rtnl_fill_info,
 	.policy = wwan_rtnl_policy,
 };
 

include/linux/wwan.h

···
 #include <linux/poll.h>
 #include <linux/skbuff.h>
 #include <linux/netlink.h>
+#include <linux/netdevice.h>
 
 /**
  * enum wwan_port_type - WWAN port types
···
  * @port: Related WWAN port
  */
 void *wwan_port_get_drvdata(struct wwan_port *port);
+
+/**
+ * struct wwan_netdev_priv - WWAN core network device private data
+ * @link_id: WWAN device data link id
+ * @drv_priv: driver private data area, size is determined in &wwan_ops
+ */
+struct wwan_netdev_priv {
+	u32 link_id;
+
+	/* must be last */
+	u8 drv_priv[] __aligned(sizeof(void *));
+};
+
+static inline void *wwan_netdev_drvpriv(struct net_device *dev)
+{
+	return ((struct wwan_netdev_priv *)netdev_priv(dev))->drv_priv;
+}
 
 /*
  * Used to indicate that the WWAN core should not create a default network