This patch builds the peer to peer communication path.
Communication is established by a negotiation process whereby messages are
sent back and forth between the peers until a connection is established.
This includes the Thunderbolt Network driver communication with the second
peer via Intel Connection Manager(ICM) firmware.
  +--------------------+            +--------------------+
  |Host 1              |            |Host 2              |
  |                    |            |                    |
  |     +-----------+  |            |     +-----------+  |
  |     |Thunderbolt|  |            |     |Thunderbolt|  |
  |     |Networking |  |            |     |Networking |  |
  |     |Driver     |  |            |     |Driver     |  |
  |     +-----------+  |            |     +-----------+  |
  |              ^     |            |              ^     |
  |              |     |            |              |     |
  | +------------+---+ |            | +------------+---+ |
  | |Thunderbolt |   | |            | |Thunderbolt |   | |
  | |Controller  v   | |            | |Controller  v   | |
  | |         +---+  | |            | |         +---+  | |
  | |         |ICM|<-+-+------------+-+-------->|ICM|  | |
  | |         +---+  | |            | |         +---+  | |
  | +----------------+ |            | +----------------+ |
  +--------------------+            +--------------------+
Note that this patch only establishes the link between the two hosts and
not Network Packet handling - this is dealt with in the next patch.

Signed-off-by: Amir Levy <redacted>
---
 drivers/thunderbolt/icm/Makefile  |   2 +-
 drivers/thunderbolt/icm/icm_nhi.c | 303 ++++++++++++++-
 drivers/thunderbolt/icm/net.c     | 793 ++++++++++++++++++++++++++++++++++++++
 drivers/thunderbolt/icm/net.h     |  70 ++++
 4 files changed, 1157 insertions(+), 11 deletions(-)
 create mode 100644 drivers/thunderbolt/icm/net.c

diff --git a/drivers/thunderbolt/icm/Makefile b/drivers/thunderbolt/icm/Makefile
index f0d0fbb..94a2797 100644
--- a/drivers/thunderbolt/icm/Makefile
+++ b/drivers/thunderbolt/icm/Makefile

@@ -1,2 +1,2 @@
 obj-${CONFIG_THUNDERBOLT_ICM} += thunderbolt-icm.o
-thunderbolt-icm-objs := icm_nhi.o
+thunderbolt-icm-objs := icm_nhi.o net.o

diff --git a/drivers/thunderbolt/icm/icm_nhi.c b/drivers/thunderbolt/icm/icm_nhi.c
index 984aa7c..578eb14 100644
--- a/drivers/thunderbolt/icm/icm_nhi.c
+++ b/drivers/thunderbolt/icm/icm_nhi.c

@@ -74,6 +74,12 @@ static const struct nla_policy nhi_genl_policy[NHI_ATTR_MAX + 1] = {
 					.len = TBT_ICM_RING_MAX_FRAME_SIZE },
 	[NHI_ATTR_MSG_FROM_ICM]		= { .type = NLA_BINARY,
 					.len = TBT_ICM_RING_MAX_FRAME_SIZE },
+	[NHI_ATTR_LOCAL_ROUTE_STRING]	= {.len = sizeof(struct route_string)},
+	[NHI_ATTR_LOCAL_UUID]		= { .len = sizeof(uuid_be) },
+	[NHI_ATTR_REMOTE_UUID]		= { .len = sizeof(uuid_be) },
+	[NHI_ATTR_LOCAL_DEPTH]		= { .type = NLA_U8, },
+	[NHI_ATTR_ENABLE_FULL_E2E]	= { .type = NLA_FLAG, },
+	[NHI_ATTR_MATCH_FRAME_ID]	= { .type = NLA_FLAG, },
 };
 
 /* NHI genetlink family */

@@ -522,6 +528,29 @@ int nhi_mailbox(struct tbt_nhi_ctxt *nhi_ctxt, u32 cmd, u32 data, bool deinit)
 	return 0;
 }
 
+static inline bool nhi_is_path_disconnected(u32 cmd, u8 num_ports)
+{
+	return (cmd >= DISCONNECT_PORT_A_INTER_DOMAIN_PATH &&
+		cmd < (DISCONNECT_PORT_A_INTER_DOMAIN_PATH + num_ports));
+}
+
+static int nhi_mailbox_disconn_path(struct tbt_nhi_ctxt *nhi_ctxt, u32 cmd)
+	__releases(&controllers_list_mutex)
+{
+	struct port_net_dev *port;
+	u32 port_num = cmd - DISCONNECT_PORT_A_INTER_DOMAIN_PATH;
+
+	port = &(nhi_ctxt->net_devices[port_num]);
+	mutex_lock(&port->state_mutex);
+
+	mutex_unlock(&controllers_list_mutex);
+	port->medium_sts = MEDIUM_READY_FOR_APPROVAL;
+	if (port->net_dev)
+		negotiation_events(port->net_dev, MEDIUM_DISCONNECTED);
+	mutex_unlock(&port->state_mutex);
+	return  0;
+}
+
 static int nhi_mailbox_generic(struct tbt_nhi_ctxt *nhi_ctxt, u32 mb_cmd)
 	__releases(&controllers_list_mutex)
 {

@@ -571,13 +600,94 @@ static int nhi_genl_mailbox(__always_unused struct sk_buff *u_skb,
 		return -ERESTART;
 
 	nhi_ctxt = nhi_search_ctxt(*(u32 *)info->userhdr);
-	if (nhi_ctxt && !nhi_ctxt->d0_exit)
-		return nhi_mailbox_generic(nhi_ctxt, mb_cmd);
+	if (nhi_ctxt && !nhi_ctxt->d0_exit) {
+
+		/* rwsem is released later by the below functions */
+		if (nhi_is_path_disconnected(cmd, nhi_ctxt->num_ports))
+			return nhi_mailbox_disconn_path(nhi_ctxt, cmd);
+		else
+			return nhi_mailbox_generic(nhi_ctxt, mb_cmd);
+
+	}
 
 	mutex_unlock(&controllers_list_mutex);
 	return -ENODEV;
 }
 
+static int nhi_genl_approve_networking(__always_unused struct sk_buff *u_skb,
+				       struct genl_info *info)
+{
+	struct tbt_nhi_ctxt *nhi_ctxt;
+	struct route_string *route_str;
+	int res = -ENODEV;
+	u8 port_num;
+
+	if (!info || !info->userhdr || !info->attrs ||
+	    !info->attrs[NHI_ATTR_LOCAL_ROUTE_STRING] ||
+	    !info->attrs[NHI_ATTR_LOCAL_UUID] ||
+	    !info->attrs[NHI_ATTR_REMOTE_UUID] ||
+	    !info->attrs[NHI_ATTR_LOCAL_DEPTH])
+		return -EINVAL;
+
+	/*
+	 * route_str is an unique topological address
+	 * used for approving remote controller
+	 */
+	route_str = nla_data(info->attrs[NHI_ATTR_LOCAL_ROUTE_STRING]);
+	/* extracts the port we're connected to */
+	port_num = PORT_NUM_FROM_LINK(L0_PORT_NUM(route_str->lo));
+
+	if (mutex_lock_interruptible(&controllers_list_mutex))
+		return -ERESTART;
+
+	nhi_ctxt = nhi_search_ctxt(*(u32 *)info->userhdr);
+	if (nhi_ctxt && !nhi_ctxt->d0_exit) {
+		struct port_net_dev *port;
+
+		if (port_num >= nhi_ctxt->num_ports) {
+			res = -EINVAL;
+			goto free_ctl_list;
+		}
+
+		port = &(nhi_ctxt->net_devices[port_num]);
+
+		mutex_lock(&port->state_mutex);
+		mutex_unlock(&controllers_list_mutex);
+
+		if (port->medium_sts != MEDIUM_READY_FOR_APPROVAL) {
+			dev_info(&nhi_ctxt->pdev->dev,
+				"%s: controller id %#x in state %u <> MEDIUM_READY_FOR_APPROVAL\n",
+				__func__, nhi_ctxt->id, port->medium_sts);