From da45d2566a1d4e260b894ff5d96be64b21c7fa79 Mon Sep 17 00:00:00 2001
From: Haijun Liu <haijun.liu@mediatek.com>
Date: Fri, 6 May 2022 11:13:02 -0700
Subject: [PATCH] net: wwan: t7xx: Add control port
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Control Port implements driver control messages such as modem-host
handshaking, controls port enumeration, and handles exception messages.

The handshaking process between the driver and the modem happens during
the init sequence. The process involves the exchange of a list of
supported runtime features to make sure that modem and host are ready
to provide proper feature lists including port enumeration. Further
features can be enabled and controlled in this handshaking process.

Signed-off-by: Haijun Liu <haijun.liu@mediatek.com>
Signed-off-by: Chandrashekar Devegowda <chandrashekar.devegowda@intel.com>
Co-developed-by: Ricardo Martinez <ricardo.martinez@linux.intel.com>
Signed-off-by: Ricardo Martinez <ricardo.martinez@linux.intel.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 drivers/net/wwan/t7xx/Makefile             |   1 +
 drivers/net/wwan/t7xx/t7xx_modem_ops.c     | 214 +++++++++++++++-
 drivers/net/wwan/t7xx/t7xx_modem_ops.h     |   3 +
 drivers/net/wwan/t7xx/t7xx_port.h          |   3 +
 drivers/net/wwan/t7xx/t7xx_port_ctrl_msg.c | 273 +++++++++++++++++++++
 drivers/net/wwan/t7xx/t7xx_port_proxy.c    |  40 +++
 drivers/net/wwan/t7xx/t7xx_port_proxy.h    |  25 ++
 drivers/net/wwan/t7xx/t7xx_state_monitor.c |   3 +
 drivers/net/wwan/t7xx/t7xx_state_monitor.h |   2 +
 9 files changed, 561 insertions(+), 3 deletions(-)
 create mode 100644 drivers/net/wwan/t7xx/t7xx_port_ctrl_msg.c

--- a/drivers/net/wwan/t7xx/Makefile
+++ b/drivers/net/wwan/t7xx/Makefile
@@ -11,3 +11,4 @@ mtk_t7xx-y:=	t7xx_pci.o \
 		t7xx_cldma.o \
 		t7xx_hif_cldma.o  \
 		t7xx_port_proxy.o  \
+		t7xx_port_ctrl_msg.o \
--- a/drivers/net/wwan/t7xx/t7xx_modem_ops.c
+++ b/drivers/net/wwan/t7xx/t7xx_modem_ops.c
@@ -16,6 +16,8 @@
  */
 
 #include <linux/acpi.h>
+#include <linux/bits.h>
+#include <linux/bitfield.h>
 #include <linux/device.h>
 #include <linux/delay.h>
 #include <linux/gfp.h>
@@ -26,6 +28,7 @@
 #include <linux/spinlock.h>
 #include <linux/string.h>
 #include <linux/types.h>
+#include <linux/wait.h>
 #include <linux/workqueue.h>
 
 #include "t7xx_cldma.h"
@@ -39,11 +42,24 @@
 #include "t7xx_reg.h"
 #include "t7xx_state_monitor.h"
 
+#define RT_ID_MD_PORT_ENUM	0
+/* Modem feature query identification code - "ICCC" */
+#define MD_FEATURE_QUERY_ID	0x49434343
+
+#define FEATURE_VER		GENMASK(7, 4)
+#define FEATURE_MSK		GENMASK(3, 0)
+
 #define RGU_RESET_DELAY_MS	10
 #define PORT_RESET_DELAY_MS	2000
 #define EX_HS_TIMEOUT_MS	5000
 #define EX_HS_POLL_DELAY_MS	10
 
+enum mtk_feature_support_type {
+	MTK_FEATURE_DOES_NOT_EXIST,
+	MTK_FEATURE_NOT_SUPPORTED,
+	MTK_FEATURE_MUST_BE_SUPPORTED,
+};
+
 static unsigned int t7xx_get_interrupt_status(struct t7xx_pci_dev *t7xx_dev)
 {
 	return t7xx_mhccif_read_sw_int_sts(t7xx_dev) & D2H_SW_INT_MASK;
@@ -314,16 +330,205 @@ static void t7xx_md_sys_sw_init(struct t
 	t7xx_pcie_register_rgu_isr(t7xx_dev);
 }
 
+struct feature_query {
+	__le32 head_pattern;
+	u8 feature_set[FEATURE_COUNT];
+	__le32 tail_pattern;
+};
+
+static void t7xx_prepare_host_rt_data_query(struct t7xx_sys_info *core)
+{
+	struct feature_query *ft_query;
+	struct sk_buff *skb;
+
+	skb = t7xx_ctrl_alloc_skb(sizeof(*ft_query));
+	if (!skb)
+		return;
+
+	ft_query = skb_put(skb, sizeof(*ft_query));
+	ft_query->head_pattern = cpu_to_le32(MD_FEATURE_QUERY_ID);
+	memcpy(ft_query->feature_set, core->feature_set, FEATURE_COUNT);
+	ft_query->tail_pattern = cpu_to_le32(MD_FEATURE_QUERY_ID);
+
+	/* Send HS1 message to device */
+	t7xx_port_send_ctl_skb(core->ctl_port, skb, CTL_ID_HS1_MSG, 0);
+}
+
+static int t7xx_prepare_device_rt_data(struct t7xx_sys_info *core, struct device *dev,
+				       void *data)
+{
+	struct feature_query *md_feature = data;
+	struct mtk_runtime_feature *rt_feature;
+	unsigned int i, rt_data_len = 0;
+	struct sk_buff *skb;
+
+	/* Parse MD runtime data query */
+	if (le32_to_cpu(md_feature->head_pattern) != MD_FEATURE_QUERY_ID ||
+	    le32_to_cpu(md_feature->tail_pattern) != MD_FEATURE_QUERY_ID) {
+		dev_err(dev, "Invalid feature pattern: head 0x%x, tail 0x%x\n",
+			le32_to_cpu(md_feature->head_pattern),
+			le32_to_cpu(md_feature->tail_pattern));
+		return -EINVAL;
+	}
+
+	for (i = 0; i < FEATURE_COUNT; i++) {
+		if (FIELD_GET(FEATURE_MSK, md_feature->feature_set[i]) !=
+		    MTK_FEATURE_MUST_BE_SUPPORTED)
+			rt_data_len += sizeof(*rt_feature);
+	}
+
+	skb = t7xx_ctrl_alloc_skb(rt_data_len);
+	if (!skb)
+		return -ENOMEM;
+
+	rt_feature = skb_put(skb, rt_data_len);
+	memset(rt_feature, 0, rt_data_len);
+
+	/* Fill runtime feature */
+	for (i = 0; i < FEATURE_COUNT; i++) {
+		u8 md_feature_mask = FIELD_GET(FEATURE_MSK, md_feature->feature_set[i]);
+
+		if (md_feature_mask == MTK_FEATURE_MUST_BE_SUPPORTED)
+			continue;
+
+		rt_feature->feature_id = i;
+		if (md_feature_mask == MTK_FEATURE_DOES_NOT_EXIST)
+			rt_feature->support_info = md_feature->feature_set[i];
+
+		rt_feature++;
+	}
+
+	/* Send HS3 message to device */
+	t7xx_port_send_ctl_skb(core->ctl_port, skb, CTL_ID_HS3_MSG, 0);
+	return 0;
+}
+
+static int t7xx_parse_host_rt_data(struct t7xx_fsm_ctl *ctl, struct t7xx_sys_info *core,
+				   struct device *dev, void *data, int data_length)
+{
+	enum mtk_feature_support_type ft_spt_st, ft_spt_cfg;
+	struct mtk_runtime_feature *rt_feature;
+	int i, offset;
+
+	offset = sizeof(struct feature_query);
+	for (i = 0; i < FEATURE_COUNT && offset < data_length; i++) {
+		rt_feature = data + offset;
+		offset += sizeof(*rt_feature) + le32_to_cpu(rt_feature->data_len);
+
+		ft_spt_cfg = FIELD_GET(FEATURE_MSK, core->feature_set[i]);
+		if (ft_spt_cfg != MTK_FEATURE_MUST_BE_SUPPORTED)
+			continue;
+
+		ft_spt_st = FIELD_GET(FEATURE_MSK, rt_feature->support_info);
+		if (ft_spt_st != MTK_FEATURE_MUST_BE_SUPPORTED)
+			return -EINVAL;
+
+		if (i == RT_ID_MD_PORT_ENUM)
+			t7xx_port_enum_msg_handler(ctl->md, rt_feature->data);
+	}
+
+	return 0;
+}
+
+static int t7xx_core_reset(struct t7xx_modem *md)
+{
+	struct device *dev = &md->t7xx_dev->pdev->dev;
+	struct t7xx_fsm_ctl *ctl = md->fsm_ctl;
+
+	md->core_md.ready = false;
+
+	if (!ctl) {
+		dev_err(dev, "FSM is not initialized\n");
+		return -EINVAL;
+	}
+
+	if (md->core_md.handshake_ongoing) {
+		int ret = t7xx_fsm_append_event(ctl, FSM_EVENT_MD_HS2_EXIT, NULL, 0);
+
+		if (ret)
+			return ret;
+	}
+
+	md->core_md.handshake_ongoing = false;
+	return 0;
+}
+
+static void t7xx_core_hk_handler(struct t7xx_modem *md, struct t7xx_fsm_ctl *ctl,
+				 enum t7xx_fsm_event_state event_id,
+				 enum t7xx_fsm_event_state err_detect)
+{
+	struct t7xx_sys_info *core_info = &md->core_md;
+	struct device *dev = &md->t7xx_dev->pdev->dev;
+	struct t7xx_fsm_event *event, *event_next;
+	unsigned long flags;
+	int ret;
+
+	t7xx_prepare_host_rt_data_query(core_info);
+
+	while (!kthread_should_stop()) {
+		bool event_received = false;
+
+		spin_lock_irqsave(&ctl->event_lock, flags);
+		list_for_each_entry_safe(event, event_next, &ctl->event_queue, entry) {
+			if (event->event_id == err_detect) {
+				list_del(&event->entry);
+				spin_unlock_irqrestore(&ctl->event_lock, flags);
+				dev_err(dev, "Core handshake error event received\n");
+				goto err_free_event;
+			} else if (event->event_id == event_id) {
+				list_del(&event->entry);
+				event_received = true;
+				break;
+			}
+		}
+		spin_unlock_irqrestore(&ctl->event_lock, flags);
+
+		if (event_received)
+			break;
+
+		wait_event_interruptible(ctl->event_wq, !list_empty(&ctl->event_queue) ||
+					 kthread_should_stop());
+		if (kthread_should_stop())
+			goto err_free_event;
+	}
+
+	if (ctl->exp_flg)
+		goto err_free_event;
+
+	ret = t7xx_parse_host_rt_data(ctl, core_info, dev, event->data, event->length);
+	if (ret) {
+		dev_err(dev, "Host failure parsing runtime data: %d\n", ret);
+		goto err_free_event;
+	}
+
+	if (ctl->exp_flg)
+		goto err_free_event;
+
+	ret = t7xx_prepare_device_rt_data(core_info, dev, event->data);
+	if (ret) {
+		dev_err(dev, "Device failure parsing runtime data: %d", ret);
+		goto err_free_event;
+	}
+
+	core_info->ready = true;
+	core_info->handshake_ongoing = false;
+	wake_up(&ctl->async_hk_wq);
+err_free_event:
+	kfree(event);
+}
+
 static void t7xx_md_hk_wq(struct work_struct *work)
 {
 	struct t7xx_modem *md = container_of(work, struct t7xx_modem, handshake_work);
 	struct t7xx_fsm_ctl *ctl = md->fsm_ctl;
 
+	/* Clear the HS2 EXIT event appended in core_reset() */
+	t7xx_fsm_clr_event(ctl, FSM_EVENT_MD_HS2_EXIT);
 	t7xx_cldma_switch_cfg(md->md_ctrl[CLDMA_ID_MD]);
 	t7xx_cldma_start(md->md_ctrl[CLDMA_ID_MD]);
 	t7xx_fsm_broadcast_state(ctl, MD_STATE_WAITING_FOR_HS2);
-	md->core_md.ready = true;
-	wake_up(&ctl->async_hk_wq);
+	md->core_md.handshake_ongoing = true;
+	t7xx_core_hk_handler(md, ctl, FSM_EVENT_MD_HS2, FSM_EVENT_MD_HS2_EXIT);
 }
 
 void t7xx_md_event_notify(struct t7xx_modem *md, enum md_event_id evt_id)
@@ -418,6 +623,9 @@ static struct t7xx_modem *t7xx_md_alloc(
 		return NULL;
 
 	INIT_WORK(&md->handshake_work, t7xx_md_hk_wq);
+	md->core_md.feature_set[RT_ID_MD_PORT_ENUM] &= ~FEATURE_MSK;
+	md->core_md.feature_set[RT_ID_MD_PORT_ENUM] |=
+		FIELD_PREP(FEATURE_MSK, MTK_FEATURE_MUST_BE_SUPPORTED);
 	return md;
 }
 
@@ -431,7 +639,7 @@ int t7xx_md_reset(struct t7xx_pci_dev *t
 	t7xx_cldma_reset(md->md_ctrl[CLDMA_ID_MD]);
 	t7xx_port_proxy_reset(md->port_prox);
 	md->md_init_finish = true;
-	return 0;
+	return t7xx_core_reset(md);
 }
 
 /**
--- a/drivers/net/wwan/t7xx/t7xx_modem_ops.h
+++ b/drivers/net/wwan/t7xx/t7xx_modem_ops.h
@@ -57,6 +57,9 @@ enum md_event_id {
 
 struct t7xx_sys_info {
 	bool				ready;
+	bool				handshake_ongoing;
+	u8				feature_set[FEATURE_COUNT];
+	struct t7xx_port		*ctl_port;
 };
 
 struct t7xx_modem {
--- a/drivers/net/wwan/t7xx/t7xx_port.h
+++ b/drivers/net/wwan/t7xx/t7xx_port.h
@@ -125,8 +125,11 @@ struct t7xx_port {
 };
 
 struct sk_buff *t7xx_port_alloc_skb(int payload);
+struct sk_buff *t7xx_ctrl_alloc_skb(int payload);
 int t7xx_port_enqueue_skb(struct t7xx_port *port, struct sk_buff *skb);
 int t7xx_port_send_skb(struct t7xx_port *port, struct sk_buff *skb, unsigned int pkt_header,
 		       unsigned int ex_msg);
+int t7xx_port_send_ctl_skb(struct t7xx_port *port, struct sk_buff *skb, unsigned int msg,
+			   unsigned int ex_msg);
 
 #endif /* __T7XX_PORT_H__ */
--- /dev/null
+++ b/drivers/net/wwan/t7xx/t7xx_port_ctrl_msg.c
@@ -0,0 +1,273 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2021, MediaTek Inc.
+ * Copyright (c) 2021-2022, Intel Corporation.
+ *
+ * Authors:
+ *  Haijun Liu <haijun.liu@mediatek.com>
+ *  Ricardo Martinez <ricardo.martinez@linux.intel.com>
+ *  Moises Veleta <moises.veleta@intel.com>
+ *
+ * Contributors:
+ *  Amir Hanania <amir.hanania@intel.com>
+ *  Chiranjeevi Rapolu <chiranjeevi.rapolu@intel.com>
+ *  Eliot Lee <eliot.lee@intel.com>
+ *  Sreehari Kancharla <sreehari.kancharla@intel.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/kthread.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/spinlock.h>
+
+#include "t7xx_port.h"
+#include "t7xx_port_proxy.h"
+#include "t7xx_state_monitor.h"
+
+#define PORT_MSG_VERSION	GENMASK(31, 16)
+#define PORT_MSG_PRT_CNT	GENMASK(15, 0)
+
+struct port_msg {
+	__le32	head_pattern;
+	__le32	info;
+	__le32	tail_pattern;
+	__le32	data[];
+};
+
+static int port_ctl_send_msg_to_md(struct t7xx_port *port, unsigned int msg, unsigned int ex_msg)
+{
+	struct sk_buff *skb;
+	int ret;
+
+	skb = t7xx_ctrl_alloc_skb(0);
+	if (!skb)
+		return -ENOMEM;
+
+	ret = t7xx_port_send_ctl_skb(port, skb, msg, ex_msg);
+	if (ret)
+		dev_kfree_skb_any(skb);
+
+	return ret;
+}
+
+static int fsm_ee_message_handler(struct t7xx_port *port, struct t7xx_fsm_ctl *ctl,
+				  struct sk_buff *skb)
+{
+	struct ctrl_msg_header *ctrl_msg_h = (struct ctrl_msg_header *)skb->data;
+	struct device *dev = &ctl->md->t7xx_dev->pdev->dev;
+	enum md_state md_state;
+	int ret = -EINVAL;
+
+	md_state = t7xx_fsm_get_md_state(ctl);
+	if (md_state != MD_STATE_EXCEPTION) {
+		dev_err(dev, "Receive invalid MD_EX %x when MD state is %d\n",
+			ctrl_msg_h->ex_msg, md_state);
+		return -EINVAL;
+	}
+
+	switch (le32_to_cpu(ctrl_msg_h->ctrl_msg_id)) {
+	case CTL_ID_MD_EX:
+		if (le32_to_cpu(ctrl_msg_h->ex_msg) != MD_EX_CHK_ID) {
+			dev_err(dev, "Receive invalid MD_EX %x\n", ctrl_msg_h->ex_msg);
+			break;
+		}
+
+		ret = port_ctl_send_msg_to_md(port, CTL_ID_MD_EX, MD_EX_CHK_ID);
+		if (ret) {
+			dev_err(dev, "Failed to send exception message to modem\n");
+			break;
+		}
+
+		ret = t7xx_fsm_append_event(ctl, FSM_EVENT_MD_EX, NULL, 0);
+		if (ret)
+			dev_err(dev, "Failed to append Modem Exception event");
+
+		break;
+
+	case CTL_ID_MD_EX_ACK:
+		if (le32_to_cpu(ctrl_msg_h->ex_msg) != MD_EX_CHK_ACK_ID) {
+			dev_err(dev, "Receive invalid MD_EX_ACK %x\n", ctrl_msg_h->ex_msg);
+			break;
+		}
+
+		ret = t7xx_fsm_append_event(ctl, FSM_EVENT_MD_EX_REC_OK, NULL, 0);
+		if (ret)
+			dev_err(dev, "Failed to append Modem Exception Received event");
+
+		break;
+
+	case CTL_ID_MD_EX_PASS:
+		ret = t7xx_fsm_append_event(ctl, FSM_EVENT_MD_EX_PASS, NULL, 0);
+		if (ret)
+			dev_err(dev, "Failed to append Modem Exception Passed event");
+
+		break;
+
+	case CTL_ID_DRV_VER_ERROR:
+		dev_err(dev, "AP/MD driver version mismatch\n");
+	}
+
+	return ret;
+}
+
+/**
+ * t7xx_port_enum_msg_handler() - Parse the port enumeration message to create/remove nodes.
+ * @md: Modem context.
+ * @msg: Message.
+ *
+ * Used to control create/remove device node.
+ *
+ * Return:
+ * * 0		- Success.
+ * * -EFAULT	- Message check failure.
+ */
+int t7xx_port_enum_msg_handler(struct t7xx_modem *md, void *msg)
+{
+	struct device *dev = &md->t7xx_dev->pdev->dev;
+	unsigned int version, port_count, i;
+	struct port_msg *port_msg = msg;
+
+	version = FIELD_GET(PORT_MSG_VERSION, le32_to_cpu(port_msg->info));
+	if (version != PORT_ENUM_VER ||
+	    le32_to_cpu(port_msg->head_pattern) != PORT_ENUM_HEAD_PATTERN ||
+	    le32_to_cpu(port_msg->tail_pattern) != PORT_ENUM_TAIL_PATTERN) {
+		dev_err(dev, "Invalid port control message %x:%x:%x\n",
+			version, le32_to_cpu(port_msg->head_pattern),
+			le32_to_cpu(port_msg->tail_pattern));
+		return -EFAULT;
+	}
+
+	port_count = FIELD_GET(PORT_MSG_PRT_CNT, le32_to_cpu(port_msg->info));
+	for (i = 0; i < port_count; i++) {
+		u32 port_info = le32_to_cpu(port_msg->data[i]);
+		unsigned int ch_id;
+		bool en_flag;
+
+		ch_id = FIELD_GET(PORT_INFO_CH_ID, port_info);
+		en_flag = port_info & PORT_INFO_ENFLG;
+		if (t7xx_port_proxy_chl_enable_disable(md->port_prox, ch_id, en_flag))
+			dev_dbg(dev, "Port:%x not found\n", ch_id);
+	}
+
+	return 0;
+}
+
+static int control_msg_handler(struct t7xx_port *port, struct sk_buff *skb)
+{
+	const struct t7xx_port_conf *port_conf = port->port_conf;
+	struct t7xx_fsm_ctl *ctl = port->t7xx_dev->md->fsm_ctl;
+	struct ctrl_msg_header *ctrl_msg_h;
+	int ret = 0;
+
+	ctrl_msg_h = (struct ctrl_msg_header *)skb->data;
+	switch (le32_to_cpu(ctrl_msg_h->ctrl_msg_id)) {
+	case CTL_ID_HS2_MSG:
+		skb_pull(skb, sizeof(*ctrl_msg_h));
+
+		if (port_conf->rx_ch == PORT_CH_CONTROL_RX) {
+			ret = t7xx_fsm_append_event(ctl, FSM_EVENT_MD_HS2, skb->data,
+						    le32_to_cpu(ctrl_msg_h->data_length));
+			if (ret)
+				dev_err(port->dev, "Failed to append Handshake 2 event");
+		}
+
+		dev_kfree_skb_any(skb);
+		break;
+
+	case CTL_ID_MD_EX:
+	case CTL_ID_MD_EX_ACK:
+	case CTL_ID_MD_EX_PASS:
+	case CTL_ID_DRV_VER_ERROR:
+		ret = fsm_ee_message_handler(port, ctl, skb);
+		dev_kfree_skb_any(skb);
+		break;
+
+	case CTL_ID_PORT_ENUM:
+		skb_pull(skb, sizeof(*ctrl_msg_h));
+		ret = t7xx_port_enum_msg_handler(ctl->md, (struct port_msg *)skb->data);
+		if (!ret)
+			ret = port_ctl_send_msg_to_md(port, CTL_ID_PORT_ENUM, 0);
+		else
+			ret = port_ctl_send_msg_to_md(port, CTL_ID_PORT_ENUM,
+						      PORT_ENUM_VER_MISMATCH);
+
+		break;
+
+	default:
+		ret = -EINVAL;
+		dev_err(port->dev, "Unknown control message ID to FSM %x\n",
+			le32_to_cpu(ctrl_msg_h->ctrl_msg_id));
+		break;
+	}
+
+	if (ret)
+		dev_err(port->dev, "%s control message handle error: %d\n", port_conf->name, ret);
+
+	return ret;
+}
+
+static int port_ctl_rx_thread(void *arg)
+{
+	while (!kthread_should_stop()) {
+		struct t7xx_port *port = arg;
+		struct sk_buff *skb;
+		unsigned long flags;
+
+		spin_lock_irqsave(&port->rx_wq.lock, flags);
+		if (skb_queue_empty(&port->rx_skb_list) &&
+		    wait_event_interruptible_locked_irq(port->rx_wq,
+							!skb_queue_empty(&port->rx_skb_list) ||
+							kthread_should_stop())) {
+			spin_unlock_irqrestore(&port->rx_wq.lock, flags);
+			continue;
+		}
+		if (kthread_should_stop()) {
+			spin_unlock_irqrestore(&port->rx_wq.lock, flags);
+			break;
+		}
+		skb = __skb_dequeue(&port->rx_skb_list);
+		spin_unlock_irqrestore(&port->rx_wq.lock, flags);
+
+		control_msg_handler(port, skb);
+	}
+
+	return 0;
+}
+
+static int port_ctl_init(struct t7xx_port *port)
+{
+	const struct t7xx_port_conf *port_conf = port->port_conf;
+
+	port->thread = kthread_run(port_ctl_rx_thread, port, "%s", port_conf->name);
+	if (IS_ERR(port->thread)) {
+		dev_err(port->dev, "Failed to start port control thread\n");
+		return PTR_ERR(port->thread);
+	}
+
+	port->rx_length_th = CTRL_QUEUE_MAXLEN;
+	return 0;
+}
+
+static void port_ctl_uninit(struct t7xx_port *port)
+{
+	unsigned long flags;
+	struct sk_buff *skb;
+
+	if (port->thread)
+		kthread_stop(port->thread);
+
+	spin_lock_irqsave(&port->rx_wq.lock, flags);
+	port->rx_length_th = 0;
+	while ((skb = __skb_dequeue(&port->rx_skb_list)) != NULL)
+		dev_kfree_skb_any(skb);
+	spin_unlock_irqrestore(&port->rx_wq.lock, flags);
+}
+
+struct port_ops ctl_port_ops = {
+	.init = port_ctl_init,
+	.recv_skb = t7xx_port_enqueue_skb,
+	.uninit = port_ctl_uninit,
+};
--- a/drivers/net/wwan/t7xx/t7xx_port_proxy.c
+++ b/drivers/net/wwan/t7xx/t7xx_port_proxy.c
@@ -49,6 +49,15 @@
 	     i++, (p) = &(proxy)->ports[i])
 
 static const struct t7xx_port_conf t7xx_md_port_conf[] = {
+	{
+		.tx_ch = PORT_CH_CONTROL_TX,
+		.rx_ch = PORT_CH_CONTROL_RX,
+		.txq_index = Q_IDX_CTRL,
+		.rxq_index = Q_IDX_CTRL,
+		.path_id = CLDMA_ID_MD,
+		.ops = &ctl_port_ops,
+		.name = "t7xx_ctrl",
+	},
 };
 
 static struct t7xx_port *t7xx_proxy_get_port_by_ch(struct port_proxy *port_prox, enum port_ch ch)
@@ -129,6 +138,16 @@ struct sk_buff *t7xx_port_alloc_skb(int
 	return skb;
 }
 
+struct sk_buff *t7xx_ctrl_alloc_skb(int payload)
+{
+	struct sk_buff *skb = t7xx_port_alloc_skb(payload + sizeof(struct ctrl_msg_header));
+
+	if (skb)
+		skb_reserve(skb, sizeof(struct ctrl_msg_header));
+
+	return skb;
+}
+
 /**
  * t7xx_port_enqueue_skb() - Enqueue the received skb into the port's rx_skb_list.
  * @port: port context.
@@ -194,6 +213,24 @@ static int t7xx_port_send_ccci_skb(struc
 	return 0;
 }
 
+int t7xx_port_send_ctl_skb(struct t7xx_port *port, struct sk_buff *skb, unsigned int msg,
+			   unsigned int ex_msg)
+{
+	struct ctrl_msg_header *ctrl_msg_h;
+	unsigned int msg_len = skb->len;
+	u32 pkt_header = 0;
+
+	ctrl_msg_h = skb_push(skb, sizeof(*ctrl_msg_h));
+	ctrl_msg_h->ctrl_msg_id = cpu_to_le32(msg);
+	ctrl_msg_h->ex_msg = cpu_to_le32(ex_msg);
+	ctrl_msg_h->data_length = cpu_to_le32(msg_len);
+
+	if (!msg_len)
+		pkt_header = CCCI_HEADER_NO_DATA;
+
+	return t7xx_port_send_ccci_skb(port, skb, pkt_header, ex_msg);
+}
+
 int t7xx_port_send_skb(struct t7xx_port *port, struct sk_buff *skb, unsigned int pkt_header,
 		       unsigned int ex_msg)
 {
@@ -359,6 +396,9 @@ static void t7xx_proxy_init_all_ports(st
 
 		t7xx_port_struct_init(port);
 
+		if (port_conf->tx_ch == PORT_CH_CONTROL_TX)
+			md->core_md.ctl_port = port;
+
 		port->t7xx_dev = md->t7xx_dev;
 		port->dev = &md->t7xx_dev->pdev->dev;
 		spin_lock_init(&port->port_update_lock);
--- a/drivers/net/wwan/t7xx/t7xx_port_proxy.h
+++ b/drivers/net/wwan/t7xx/t7xx_port_proxy.h
@@ -53,6 +53,27 @@ struct ccci_header {
 #define CCCI_H_SEQ_FLD		GENMASK(30, 16)
 #define CCCI_H_CHN_FLD		GENMASK(15, 0)
 
+struct ctrl_msg_header {
+	__le32	ctrl_msg_id;
+	__le32	ex_msg;
+	__le32	data_length;
+};
+
+/* Control identification numbers for AP<->MD messages  */
+#define CTL_ID_HS1_MSG		0x0
+#define CTL_ID_HS2_MSG		0x1
+#define CTL_ID_HS3_MSG		0x2
+#define CTL_ID_MD_EX		0x4
+#define CTL_ID_DRV_VER_ERROR	0x5
+#define CTL_ID_MD_EX_ACK	0x6
+#define CTL_ID_MD_EX_PASS	0x8
+#define CTL_ID_PORT_ENUM	0x9
+
+/* Modem exception check identification code - "EXCP" */
+#define MD_EX_CHK_ID		0x45584350
+/* Modem exception check acknowledge identification code - "EREC" */
+#define MD_EX_CHK_ACK_ID	0x45524543
+
 #define PORT_INFO_RSRVD		GENMASK(31, 16)
 #define PORT_INFO_ENFLG		BIT(15)
 #define PORT_INFO_CH_ID		GENMASK(14, 0)
@@ -62,10 +83,14 @@ struct ccci_header {
 #define PORT_ENUM_TAIL_PATTERN	0xa5a5a5a5
 #define PORT_ENUM_VER_MISMATCH	0x00657272
 
+/* Port operations mapping */
+extern struct port_ops ctl_port_ops;
+
 void t7xx_port_proxy_reset(struct port_proxy *port_prox);
 void t7xx_port_proxy_uninit(struct port_proxy *port_prox);
 int t7xx_port_proxy_init(struct t7xx_modem *md);
 void t7xx_port_proxy_md_status_notify(struct port_proxy *port_prox, unsigned int state);
+int t7xx_port_enum_msg_handler(struct t7xx_modem *md, void *msg);
 int t7xx_port_proxy_chl_enable_disable(struct port_proxy *port_prox, unsigned int ch_id,
 				       bool en_flag);
 
--- a/drivers/net/wwan/t7xx/t7xx_state_monitor.c
+++ b/drivers/net/wwan/t7xx/t7xx_state_monitor.c
@@ -293,6 +293,9 @@ static int fsm_routine_starting(struct t
 
 	if (!md->core_md.ready) {
 		dev_err(dev, "MD handshake timeout\n");
+		if (md->core_md.handshake_ongoing)
+			t7xx_fsm_append_event(ctl, FSM_EVENT_MD_HS2_EXIT, NULL, 0);
+
 		fsm_routine_exception(ctl, NULL, EXCEPTION_HS_TIMEOUT);
 		return -ETIMEDOUT;
 	}
--- a/drivers/net/wwan/t7xx/t7xx_state_monitor.h
+++ b/drivers/net/wwan/t7xx/t7xx_state_monitor.h
@@ -37,9 +37,11 @@ enum t7xx_fsm_state {
 
 enum t7xx_fsm_event_state {
 	FSM_EVENT_INVALID,
+	FSM_EVENT_MD_HS2,
 	FSM_EVENT_MD_EX,
 	FSM_EVENT_MD_EX_REC_OK,
 	FSM_EVENT_MD_EX_PASS,
+	FSM_EVENT_MD_HS2_EXIT,
 	FSM_EVENT_MAX
 };
 
