drivers/net/ipa/ipa_modem.c - SHIFTPHONES/mainline/linux - Gitiles

 // SPDX-License-Identifier: GPL-2.0

 /* Copyright (c) 2014-2018, The Linux Foundation. All rights reserved.
  * Copyright (C) 2018-2021 Linaro Ltd.
  */

 #include <linux/errno.h>
 #include <linux/if_arp.h>
 #include <linux/netdevice.h>
 #include <linux/skbuff.h>
 #include <linux/if_rmnet.h>
 #include <linux/pm_runtime.h>
 #include <linux/remoteproc/qcom_rproc.h>

 #include "ipa.h"
 #include "ipa_data.h"
 #include "ipa_endpoint.h"
 #include "ipa_table.h"
 #include "ipa_mem.h"
 #include "ipa_modem.h"
 #include "ipa_smp2p.h"
 #include "ipa_qmi.h"
 #include "ipa_uc.h"
 #include "ipa_power.h"

 #define IPA_NETDEV_NAME		"rmnet_ipa%d"
 #define IPA_NETDEV_TAILROOM	0	/* for padding by mux layer */
 #define IPA_NETDEV_TIMEOUT	10	/* seconds */

 enum ipa_modem_state {
 	IPA_MODEM_STATE_STOPPED	= 0,
 	IPA_MODEM_STATE_STARTING,
 	IPA_MODEM_STATE_RUNNING,
 	IPA_MODEM_STATE_STOPPING,
 };

 /**
  * struct ipa_priv - IPA network device private data
  * @ipa:	IPA pointer
  * @work:	Work structure used to wake the modem netdev TX queue
  */
 struct ipa_priv {
 	struct ipa *ipa;
 	struct work_struct work;
 };

 /** ipa_open() - Opens the modem network interface */
 static int ipa_open(struct net_device *netdev)
 {
 	struct ipa_priv *priv = netdev_priv(netdev);
 	struct ipa *ipa = priv->ipa;
 	struct device *dev;
 	int ret;

 	dev = &ipa->pdev->dev;
 	ret = pm_runtime_get_sync(dev);
 	if (ret < 0)
 		goto err_power_put;

 	ret = ipa_endpoint_enable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
 	if (ret)
 		goto err_power_put;

 	ret = ipa_endpoint_enable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
 	if (ret)
 		goto err_disable_tx;

 	netif_start_queue(netdev);

 	pm_runtime_mark_last_busy(dev);
 	(void)pm_runtime_put_autosuspend(dev);

 	return 0;

 err_disable_tx:
 	ipa_endpoint_disable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
 err_power_put:
 	pm_runtime_put_noidle(dev);

 	return ret;
 }

 /** ipa_stop() - Stops the modem network interface. */
 static int ipa_stop(struct net_device *netdev)
 {
 	struct ipa_priv *priv = netdev_priv(netdev);
 	struct ipa *ipa = priv->ipa;
 	struct device *dev;
 	int ret;

 	dev = &ipa->pdev->dev;
 	ret = pm_runtime_get_sync(dev);
 	if (ret < 0)
 		goto out_power_put;

 	netif_stop_queue(netdev);

 	ipa_endpoint_disable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
 	ipa_endpoint_disable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
 out_power_put:
 	pm_runtime_mark_last_busy(dev);
 	(void)pm_runtime_put_autosuspend(dev);

 	return 0;
 }

 /** ipa_start_xmit() - Transmits an skb.
  * @skb: skb to be transmitted
  * @dev: network device
  *
  * Return codes:
  * NETDEV_TX_OK: Success
  * NETDEV_TX_BUSY: Error while transmitting the skb. Try again later
  */
 static netdev_tx_t
 ipa_start_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
 	struct net_device_stats *stats = &netdev->stats;
 	struct ipa_priv *priv = netdev_priv(netdev);
 	struct ipa_endpoint *endpoint;
 	struct ipa *ipa = priv->ipa;
 	u32 skb_len = skb->len;
 	struct device *dev;
 	int ret;

 	if (!skb_len)
 		goto err_drop_skb;

 	endpoint = ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX];
 	if (endpoint->data->qmap && skb->protocol != htons(ETH_P_MAP))
 		goto err_drop_skb;

 	/* The hardware must be powered for us to transmit */
 	dev = &ipa->pdev->dev;
 	ret = pm_runtime_get(dev);
 	if (ret < 1) {
 		/* If a resume won't happen, just drop the packet */
 		if (ret < 0 && ret != -EINPROGRESS) {
 			ipa_power_modem_queue_active(ipa);
 			pm_runtime_put_noidle(dev);
 			goto err_drop_skb;
 		}

 		/* No power (yet).  Stop the network stack from transmitting
 		 * until we're resumed; ipa_modem_resume() arranges for the
 		 * TX queue to be started again.
 		 */
 		ipa_power_modem_queue_stop(ipa);

 		pm_runtime_put_noidle(dev);

 		return NETDEV_TX_BUSY;
 	}

 	ipa_power_modem_queue_active(ipa);

 	ret = ipa_endpoint_skb_tx(endpoint, skb);

 	pm_runtime_mark_last_busy(dev);
 	(void)pm_runtime_put_autosuspend(dev);

 	if (ret) {
 		if (ret != -E2BIG)
 			return NETDEV_TX_BUSY;
 		goto err_drop_skb;
 	}

 	stats->tx_packets++;
 	stats->tx_bytes += skb_len;

 	return NETDEV_TX_OK;

 err_drop_skb:
 	dev_kfree_skb_any(skb);
 	stats->tx_dropped++;

 	return NETDEV_TX_OK;
 }

 void ipa_modem_skb_rx(struct net_device *netdev, struct sk_buff *skb)
 {
 	struct net_device_stats *stats = &netdev->stats;

 	if (skb) {
 		skb->dev = netdev;
 		skb->protocol = htons(ETH_P_MAP);
 		stats->rx_packets++;
 		stats->rx_bytes += skb->len;

 		(void)netif_receive_skb(skb);
 	} else {
 		stats->rx_dropped++;
 	}
 }

 static const struct net_device_ops ipa_modem_ops = {
 	.ndo_open	= ipa_open,
 	.ndo_stop	= ipa_stop,
 	.ndo_start_xmit	= ipa_start_xmit,
 };

 /** ipa_modem_netdev_setup() - netdev setup function for the modem */
 static void ipa_modem_netdev_setup(struct net_device *netdev)
 {
 	netdev->netdev_ops = &ipa_modem_ops;
 	ether_setup(netdev);
 	/* No header ops (override value set by ether_setup()) */
 	netdev->header_ops = NULL;
 	netdev->type = ARPHRD_RAWIP;
 	netdev->hard_header_len = 0;
 	netdev->max_mtu = IPA_MTU;
 	netdev->mtu = netdev->max_mtu;
 	netdev->addr_len = 0;
 	netdev->flags &= ~(IFF_BROADCAST | IFF_MULTICAST);
 	/* The endpoint is configured for QMAP */
 	netdev->needed_headroom = sizeof(struct rmnet_map_header);
 	netdev->needed_tailroom = IPA_NETDEV_TAILROOM;
 	netdev->watchdog_timeo = IPA_NETDEV_TIMEOUT * HZ;
 	netdev->hw_features = NETIF_F_SG;
 }

 /** ipa_modem_suspend() - suspend callback
  * @netdev:	Network device
  *
  * Suspend the modem's endpoints.
  */
 void ipa_modem_suspend(struct net_device *netdev)
 {
 	struct ipa_priv *priv = netdev_priv(netdev);
 	struct ipa *ipa = priv->ipa;

 	if (!(netdev->flags & IFF_UP))
 		return;

 	ipa_endpoint_suspend_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
 	ipa_endpoint_suspend_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
 }

 /**
  * ipa_modem_wake_queue_work() - enable modem netdev queue
  * @work:	Work structure
  *
  * Re-enable transmit on the modem network device.  This is called
  * in (power management) work queue context, scheduled when resuming
  * the modem.  We can't enable the queue directly in ipa_modem_resume()
  * because transmits restart the instant the queue is awakened; but the
  * device power state won't be ACTIVE until *after* ipa_modem_resume()
  * returns.
  */
 static void ipa_modem_wake_queue_work(struct work_struct *work)
 {
 	struct ipa_priv *priv = container_of(work, struct ipa_priv, work);

 	ipa_power_modem_queue_wake(priv->ipa);
 }

 /** ipa_modem_resume() - resume callback for runtime_pm
  * @dev: pointer to device
  *
  * Resume the modem's endpoints.
  */
 void ipa_modem_resume(struct net_device *netdev)
 {
 	struct ipa_priv *priv = netdev_priv(netdev);
 	struct ipa *ipa = priv->ipa;

 	if (!(netdev->flags & IFF_UP))
 		return;

 	ipa_endpoint_resume_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
 	ipa_endpoint_resume_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);

 	/* Arrange for the TX queue to be restarted */
 	(void)queue_pm_work(&priv->work);
 }

 int ipa_modem_start(struct ipa *ipa)
 {
 	enum ipa_modem_state state;
 	struct net_device *netdev;
 	struct ipa_priv *priv;
 	int ret;

 	/* Only attempt to start the modem if it's stopped */
 	state = atomic_cmpxchg(&ipa->modem_state, IPA_MODEM_STATE_STOPPED,
 			       IPA_MODEM_STATE_STARTING);

 	/* Silently ignore attempts when running, or when changing state */
 	if (state != IPA_MODEM_STATE_STOPPED)
 		return 0;

 	netdev = alloc_netdev(sizeof(struct ipa_priv), IPA_NETDEV_NAME,
 			      NET_NAME_UNKNOWN, ipa_modem_netdev_setup);
 	if (!netdev) {
 		ret = -ENOMEM;
 		goto out_set_state;
 	}

 	SET_NETDEV_DEV(netdev, &ipa->pdev->dev);
 	priv = netdev_priv(netdev);
 	priv->ipa = ipa;
 	INIT_WORK(&priv->work, ipa_modem_wake_queue_work);
 	ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]->netdev = netdev;
 	ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]->netdev = netdev;
 	ipa->modem_netdev = netdev;

 	ret = register_netdev(netdev);
 	if (ret) {
 		ipa->modem_netdev = NULL;
 		ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]->netdev = NULL;
 		ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]->netdev = NULL;
 		free_netdev(netdev);
 	}

 out_set_state:
 	if (ret)
 		atomic_set(&ipa->modem_state, IPA_MODEM_STATE_STOPPED);
 	else
 		atomic_set(&ipa->modem_state, IPA_MODEM_STATE_RUNNING);
 	smp_mb__after_atomic();

 	return ret;
 }

 int ipa_modem_stop(struct ipa *ipa)
 {
 	struct net_device *netdev = ipa->modem_netdev;
 	enum ipa_modem_state state;

 	/* Only attempt to stop the modem if it's running */
 	state = atomic_cmpxchg(&ipa->modem_state, IPA_MODEM_STATE_RUNNING,
 			       IPA_MODEM_STATE_STOPPING);

 	/* Silently ignore attempts when already stopped */
 	if (state == IPA_MODEM_STATE_STOPPED)
 		return 0;

 	/* If we're somewhere between stopped and starting, we're busy */
 	if (state != IPA_MODEM_STATE_RUNNING)
 		return -EBUSY;

 	/* Clean up the netdev and endpoints if it was started */
 	if (netdev) {
 		struct ipa_priv *priv = netdev_priv(netdev);

 		cancel_work_sync(&priv->work);
 		/* If it was opened, stop it first */
 		if (netdev->flags & IFF_UP)
 			(void)ipa_stop(netdev);
 		unregister_netdev(netdev);
 		ipa->modem_netdev = NULL;
 		ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]->netdev = NULL;
 		ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]->netdev = NULL;
 		free_netdev(netdev);
 	}

 	atomic_set(&ipa->modem_state, IPA_MODEM_STATE_STOPPED);
 	smp_mb__after_atomic();

 	return 0;
 }

 /* Treat a "clean" modem stop the same as a crash */
 static void ipa_modem_crashed(struct ipa *ipa)
 {
 	struct device *dev = &ipa->pdev->dev;
 	int ret;

 	/* Prevent the modem from triggering a call to ipa_setup() */
 	ipa_smp2p_irq_disable_setup(ipa);

 	ret = pm_runtime_get_sync(dev);
 	if (ret < 0) {
 		dev_err(dev, "error %d getting power to handle crash\n", ret);
 		goto out_power_put;
 	}

 	ipa_endpoint_modem_pause_all(ipa, true);

 	ipa_endpoint_modem_hol_block_clear_all(ipa);

 	ipa_table_reset(ipa, true);

 	ret = ipa_table_hash_flush(ipa);
 	if (ret)
 		dev_err(dev, "error %d flushing hash caches\n", ret);

 	ret = ipa_endpoint_modem_exception_reset_all(ipa);
 	if (ret)
 		dev_err(dev, "error %d resetting exception endpoint\n", ret);

 	ipa_endpoint_modem_pause_all(ipa, false);

 	ret = ipa_modem_stop(ipa);
 	if (ret)
 		dev_err(dev, "error %d stopping modem\n", ret);

 	/* Now prepare for the next modem boot */
 	ret = ipa_mem_zero_modem(ipa);
 	if (ret)
 		dev_err(dev, "error %d zeroing modem memory regions\n", ret);

 out_power_put:
 	pm_runtime_mark_last_busy(dev);
 	(void)pm_runtime_put_autosuspend(dev);
 }

 static int ipa_modem_notify(struct notifier_block *nb, unsigned long action,
 			    void *data)
 {
 	struct ipa *ipa = container_of(nb, struct ipa, nb);
 	struct qcom_ssr_notify_data *notify_data = data;
 	struct device *dev = &ipa->pdev->dev;

 	switch (action) {
 	case QCOM_SSR_BEFORE_POWERUP:
 		dev_info(dev, "received modem starting event\n");
 		ipa_uc_power(ipa);
 		ipa_smp2p_notify_reset(ipa);
 		break;

 	case QCOM_SSR_AFTER_POWERUP:
 		dev_info(dev, "received modem running event\n");
 		break;

 	case QCOM_SSR_BEFORE_SHUTDOWN:
 		dev_info(dev, "received modem %s event\n",
 			 notify_data->crashed ? "crashed" : "stopping");
 		if (ipa->setup_complete)
 			ipa_modem_crashed(ipa);
 		break;

 	case QCOM_SSR_AFTER_SHUTDOWN:
 		dev_info(dev, "received modem offline event\n");
 		break;

 	default:
 		dev_err(dev, "received unrecognized event %lu\n", action);
 		break;
 	}

 	return NOTIFY_OK;
 }

 int ipa_modem_config(struct ipa *ipa)
 {
 	void *notifier;

 	ipa->nb.notifier_call = ipa_modem_notify;

 	notifier = qcom_register_ssr_notifier("mpss", &ipa->nb);
 	if (IS_ERR(notifier))
 		return PTR_ERR(notifier);

 	ipa->notifier = notifier;

 	return 0;
 }

 void ipa_modem_deconfig(struct ipa *ipa)
 {
 	struct device *dev = &ipa->pdev->dev;
 	int ret;

 	ret = qcom_unregister_ssr_notifier(ipa->notifier, &ipa->nb);
 	if (ret)
 		dev_err(dev, "error %d unregistering notifier", ret);

 	ipa->notifier = NULL;
 	memset(&ipa->nb, 0, sizeof(ipa->nb));
 }
	// SPDX-License-Identifier: GPL-2.0

	/* Copyright (c) 2014-2018, The Linux Foundation. All rights reserved.
	* Copyright (C) 2018-2021 Linaro Ltd.
	*/

	#include <linux/errno.h>
	#include <linux/if_arp.h>
	#include <linux/netdevice.h>
	#include <linux/skbuff.h>
	#include <linux/if_rmnet.h>
	#include <linux/pm_runtime.h>
	#include <linux/remoteproc/qcom_rproc.h>

	#include "ipa.h"
	#include "ipa_data.h"
	#include "ipa_endpoint.h"
	#include "ipa_table.h"
	#include "ipa_mem.h"
	#include "ipa_modem.h"
	#include "ipa_smp2p.h"
	#include "ipa_qmi.h"
	#include "ipa_uc.h"
	#include "ipa_power.h"

	#define IPA_NETDEV_NAME "rmnet_ipa%d"
	#define IPA_NETDEV_TAILROOM 0 /* for padding by mux layer */
	#define IPA_NETDEV_TIMEOUT 10 /* seconds */

	enum ipa_modem_state {
	IPA_MODEM_STATE_STOPPED = 0,
	IPA_MODEM_STATE_STARTING,
	IPA_MODEM_STATE_RUNNING,
	IPA_MODEM_STATE_STOPPING,
	};

	/**
	* struct ipa_priv - IPA network device private data
	* @ipa: IPA pointer
	* @work: Work structure used to wake the modem netdev TX queue
	*/
	struct ipa_priv {
	struct ipa *ipa;
	struct work_struct work;
	};

	/** ipa_open() - Opens the modem network interface */
	static int ipa_open(struct net_device *netdev)
	{
	struct ipa_priv *priv = netdev_priv(netdev);
	struct ipa *ipa = priv->ipa;
	struct device *dev;
	int ret;

	dev = &ipa->pdev->dev;
	ret = pm_runtime_get_sync(dev);
	if (ret < 0)
	goto err_power_put;

	ret = ipa_endpoint_enable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
	if (ret)
	goto err_power_put;

	ret = ipa_endpoint_enable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
	if (ret)
	goto err_disable_tx;

	netif_start_queue(netdev);

	pm_runtime_mark_last_busy(dev);
	(void)pm_runtime_put_autosuspend(dev);

	return 0;

	err_disable_tx:
	ipa_endpoint_disable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
	err_power_put:
	pm_runtime_put_noidle(dev);

	return ret;
	}

	/** ipa_stop() - Stops the modem network interface. */
	static int ipa_stop(struct net_device *netdev)
	{
	struct ipa_priv *priv = netdev_priv(netdev);
	struct ipa *ipa = priv->ipa;
	struct device *dev;
	int ret;

	dev = &ipa->pdev->dev;
	ret = pm_runtime_get_sync(dev);
	if (ret < 0)
	goto out_power_put;

	netif_stop_queue(netdev);

	ipa_endpoint_disable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
	ipa_endpoint_disable_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
	out_power_put:
	pm_runtime_mark_last_busy(dev);
	(void)pm_runtime_put_autosuspend(dev);

	return 0;
	}

	/** ipa_start_xmit() - Transmits an skb.
	* @skb: skb to be transmitted
	* @dev: network device
	*
	* Return codes:
	* NETDEV_TX_OK: Success
	* NETDEV_TX_BUSY: Error while transmitting the skb. Try again later
	*/
	static netdev_tx_t
	ipa_start_xmit(struct sk_buff skb, struct net_device netdev)
	{
	struct net_device_stats *stats = &netdev->stats;
	struct ipa_priv *priv = netdev_priv(netdev);
	struct ipa_endpoint *endpoint;
	struct ipa *ipa = priv->ipa;
	u32 skb_len = skb->len;
	struct device *dev;
	int ret;

	if (!skb_len)
	goto err_drop_skb;

	endpoint = ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX];
	if (endpoint->data->qmap && skb->protocol != htons(ETH_P_MAP))
	goto err_drop_skb;

	/* The hardware must be powered for us to transmit */
	dev = &ipa->pdev->dev;
	ret = pm_runtime_get(dev);
	if (ret < 1) {
	/* If a resume won't happen, just drop the packet */
	if (ret < 0 && ret != -EINPROGRESS) {
	ipa_power_modem_queue_active(ipa);
	pm_runtime_put_noidle(dev);
	goto err_drop_skb;
	}

	/* No power (yet). Stop the network stack from transmitting
	* until we're resumed; ipa_modem_resume() arranges for the
	* TX queue to be started again.
	*/
	ipa_power_modem_queue_stop(ipa);

	pm_runtime_put_noidle(dev);

	return NETDEV_TX_BUSY;
	}

	ipa_power_modem_queue_active(ipa);

	ret = ipa_endpoint_skb_tx(endpoint, skb);

	pm_runtime_mark_last_busy(dev);
	(void)pm_runtime_put_autosuspend(dev);

	if (ret) {
	if (ret != -E2BIG)
	return NETDEV_TX_BUSY;
	goto err_drop_skb;
	}

	stats->tx_packets++;
	stats->tx_bytes += skb_len;

	return NETDEV_TX_OK;

	err_drop_skb:
	dev_kfree_skb_any(skb);
	stats->tx_dropped++;

	return NETDEV_TX_OK;
	}

	void ipa_modem_skb_rx(struct net_device netdev, struct sk_buff skb)
	{
	struct net_device_stats *stats = &netdev->stats;

	if (skb) {
	skb->dev = netdev;
	skb->protocol = htons(ETH_P_MAP);
	stats->rx_packets++;
	stats->rx_bytes += skb->len;

	(void)netif_receive_skb(skb);
	} else {
	stats->rx_dropped++;
	}
	}

	static const struct net_device_ops ipa_modem_ops = {
	.ndo_open = ipa_open,
	.ndo_stop = ipa_stop,
	.ndo_start_xmit = ipa_start_xmit,
	};

	/** ipa_modem_netdev_setup() - netdev setup function for the modem */
	static void ipa_modem_netdev_setup(struct net_device *netdev)
	{
	netdev->netdev_ops = &ipa_modem_ops;
	ether_setup(netdev);
	/* No header ops (override value set by ether_setup()) */
	netdev->header_ops = NULL;
	netdev->type = ARPHRD_RAWIP;
	netdev->hard_header_len = 0;
	netdev->max_mtu = IPA_MTU;
	netdev->mtu = netdev->max_mtu;
	netdev->addr_len = 0;
	netdev->flags &= ~(IFF_BROADCAST \| IFF_MULTICAST);
	/* The endpoint is configured for QMAP */
	netdev->needed_headroom = sizeof(struct rmnet_map_header);
	netdev->needed_tailroom = IPA_NETDEV_TAILROOM;
	netdev->watchdog_timeo = IPA_NETDEV_TIMEOUT * HZ;
	netdev->hw_features = NETIF_F_SG;
	}

	/** ipa_modem_suspend() - suspend callback
	* @netdev: Network device
	*
	* Suspend the modem's endpoints.
	*/
	void ipa_modem_suspend(struct net_device *netdev)
	{
	struct ipa_priv *priv = netdev_priv(netdev);
	struct ipa *ipa = priv->ipa;

	if (!(netdev->flags & IFF_UP))
	return;

	ipa_endpoint_suspend_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);
	ipa_endpoint_suspend_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
	}

	/**
	* ipa_modem_wake_queue_work() - enable modem netdev queue
	* @work: Work structure
	*
	* Re-enable transmit on the modem network device. This is called
	* in (power management) work queue context, scheduled when resuming
	* the modem. We can't enable the queue directly in ipa_modem_resume()
	* because transmits restart the instant the queue is awakened; but the
	* device power state won't be ACTIVE until after ipa_modem_resume()
	* returns.
	*/
	static void ipa_modem_wake_queue_work(struct work_struct *work)
	{
	struct ipa_priv *priv = container_of(work, struct ipa_priv, work);

	ipa_power_modem_queue_wake(priv->ipa);
	}

	/** ipa_modem_resume() - resume callback for runtime_pm
	* @dev: pointer to device
	*
	* Resume the modem's endpoints.
	*/
	void ipa_modem_resume(struct net_device *netdev)
	{
	struct ipa_priv *priv = netdev_priv(netdev);
	struct ipa *ipa = priv->ipa;

	if (!(netdev->flags & IFF_UP))
	return;

	ipa_endpoint_resume_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]);
	ipa_endpoint_resume_one(ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]);

	/* Arrange for the TX queue to be restarted */
	(void)queue_pm_work(&priv->work);
	}

	int ipa_modem_start(struct ipa *ipa)
	{
	enum ipa_modem_state state;
	struct net_device *netdev;
	struct ipa_priv *priv;
	int ret;

	/* Only attempt to start the modem if it's stopped */
	state = atomic_cmpxchg(&ipa->modem_state, IPA_MODEM_STATE_STOPPED,
	IPA_MODEM_STATE_STARTING);

	/* Silently ignore attempts when running, or when changing state */
	if (state != IPA_MODEM_STATE_STOPPED)
	return 0;

	netdev = alloc_netdev(sizeof(struct ipa_priv), IPA_NETDEV_NAME,
	NET_NAME_UNKNOWN, ipa_modem_netdev_setup);
	if (!netdev) {
	ret = -ENOMEM;
	goto out_set_state;
	}

	SET_NETDEV_DEV(netdev, &ipa->pdev->dev);
	priv = netdev_priv(netdev);
	priv->ipa = ipa;
	INIT_WORK(&priv->work, ipa_modem_wake_queue_work);
	ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]->netdev = netdev;
	ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]->netdev = netdev;
	ipa->modem_netdev = netdev;

	ret = register_netdev(netdev);
	if (ret) {
	ipa->modem_netdev = NULL;
	ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]->netdev = NULL;
	ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]->netdev = NULL;
	free_netdev(netdev);
	}

	out_set_state:
	if (ret)
	atomic_set(&ipa->modem_state, IPA_MODEM_STATE_STOPPED);
	else
	atomic_set(&ipa->modem_state, IPA_MODEM_STATE_RUNNING);
	smp_mb__after_atomic();

	return ret;
	}

	int ipa_modem_stop(struct ipa *ipa)
	{
	struct net_device *netdev = ipa->modem_netdev;
	enum ipa_modem_state state;

	/* Only attempt to stop the modem if it's running */
	state = atomic_cmpxchg(&ipa->modem_state, IPA_MODEM_STATE_RUNNING,
	IPA_MODEM_STATE_STOPPING);

	/* Silently ignore attempts when already stopped */
	if (state == IPA_MODEM_STATE_STOPPED)
	return 0;

	/* If we're somewhere between stopped and starting, we're busy */
	if (state != IPA_MODEM_STATE_RUNNING)
	return -EBUSY;

	/* Clean up the netdev and endpoints if it was started */
	if (netdev) {
	struct ipa_priv *priv = netdev_priv(netdev);

	cancel_work_sync(&priv->work);
	/* If it was opened, stop it first */
	if (netdev->flags & IFF_UP)
	(void)ipa_stop(netdev);
	unregister_netdev(netdev);
	ipa->modem_netdev = NULL;
	ipa->name_map[IPA_ENDPOINT_AP_MODEM_RX]->netdev = NULL;
	ipa->name_map[IPA_ENDPOINT_AP_MODEM_TX]->netdev = NULL;
	free_netdev(netdev);
	}

	atomic_set(&ipa->modem_state, IPA_MODEM_STATE_STOPPED);
	smp_mb__after_atomic();

	return 0;
	}

	/* Treat a "clean" modem stop the same as a crash */
	static void ipa_modem_crashed(struct ipa *ipa)
	{
	struct device *dev = &ipa->pdev->dev;
	int ret;

	/* Prevent the modem from triggering a call to ipa_setup() */
	ipa_smp2p_irq_disable_setup(ipa);

	ret = pm_runtime_get_sync(dev);
	if (ret < 0) {
	dev_err(dev, "error %d getting power to handle crash\n", ret);
	goto out_power_put;
	}

	ipa_endpoint_modem_pause_all(ipa, true);

	ipa_endpoint_modem_hol_block_clear_all(ipa);

	ipa_table_reset(ipa, true);

	ret = ipa_table_hash_flush(ipa);
	if (ret)
	dev_err(dev, "error %d flushing hash caches\n", ret);

	ret = ipa_endpoint_modem_exception_reset_all(ipa);
	if (ret)
	dev_err(dev, "error %d resetting exception endpoint\n", ret);

	ipa_endpoint_modem_pause_all(ipa, false);

	ret = ipa_modem_stop(ipa);
	if (ret)
	dev_err(dev, "error %d stopping modem\n", ret);

	/* Now prepare for the next modem boot */
	ret = ipa_mem_zero_modem(ipa);
	if (ret)
	dev_err(dev, "error %d zeroing modem memory regions\n", ret);

	out_power_put:
	pm_runtime_mark_last_busy(dev);
	(void)pm_runtime_put_autosuspend(dev);
	}

	static int ipa_modem_notify(struct notifier_block *nb, unsigned long action,
	void *data)
	{
	struct ipa *ipa = container_of(nb, struct ipa, nb);
	struct qcom_ssr_notify_data *notify_data = data;
	struct device *dev = &ipa->pdev->dev;

	switch (action) {
	case QCOM_SSR_BEFORE_POWERUP:
	dev_info(dev, "received modem starting event\n");
	ipa_uc_power(ipa);
	ipa_smp2p_notify_reset(ipa);
	break;

	case QCOM_SSR_AFTER_POWERUP:
	dev_info(dev, "received modem running event\n");
	break;

	case QCOM_SSR_BEFORE_SHUTDOWN:
	dev_info(dev, "received modem %s event\n",
	notify_data->crashed ? "crashed" : "stopping");
	if (ipa->setup_complete)
	ipa_modem_crashed(ipa);
	break;

	case QCOM_SSR_AFTER_SHUTDOWN:
	dev_info(dev, "received modem offline event\n");
	break;

	default:
	dev_err(dev, "received unrecognized event %lu\n", action);
	break;
	}

	return NOTIFY_OK;
	}

	int ipa_modem_config(struct ipa *ipa)
	{
	void *notifier;

	ipa->nb.notifier_call = ipa_modem_notify;

	notifier = qcom_register_ssr_notifier("mpss", &ipa->nb);
	if (IS_ERR(notifier))
	return PTR_ERR(notifier);

	ipa->notifier = notifier;

	return 0;
	}

	void ipa_modem_deconfig(struct ipa *ipa)
	{
	struct device *dev = &ipa->pdev->dev;
	int ret;

	ret = qcom_unregister_ssr_notifier(ipa->notifier, &ipa->nb);
	if (ret)
	dev_err(dev, "error %d unregistering notifier", ret);

	ipa->notifier = NULL;
	memset(&ipa->nb, 0, sizeof(ipa->nb));
	}