drivers/misc/mic/cosm/cosm_scif_server.c - kernel/quantenna - Git at Google

 /*
  * Intel MIC Platform Software Stack (MPSS)
  *
  * Copyright(c) 2015 Intel Corporation.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, version 2, as
  * published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  * General Public License for more details.
  *
  * The full GNU General Public License is included in this distribution in
  * the file called "COPYING".
  *
  * Intel MIC Coprocessor State Management (COSM) Driver
  *
  */
 #include <linux/kthread.h>
 #include "cosm_main.h"

 /*
  * The COSM driver uses SCIF to communicate between the management node and the
  * MIC cards. SCIF is used to (a) Send a shutdown command to the card (b)
  * receive a shutdown status back from the card upon completion of shutdown and
  * (c) receive periodic heartbeat messages from the card used to deduce if the
  * card has crashed.
  *
  * A COSM server consisting of a SCIF listening endpoint waits for incoming
  * connections from the card. Upon acceptance of the connection, a separate
  * work-item is scheduled to handle SCIF message processing for that card. The
  * life-time of this work-item is therefore the time from which the connection
  * from a card is accepted to the time at which the connection is closed. A new
  * work-item starts each time the card boots and is alive till the card (a)
  * shuts down (b) is reset (c) crashes (d) cosm_client driver on the card is
  * unloaded.
  *
  * From the point of view of COSM interactions with SCIF during card
  * shutdown, reset and crash are as follows:
  *
  * Card shutdown
  * -------------
  * 1. COSM client on the card invokes orderly_poweroff() in response to SHUTDOWN
  *    message from the host.
  * 2. Card driver shutdown callback invokes scif_unregister_device(..) resulting
  *    in scif_remove(..) getting called on the card
  * 3. scif_remove -> scif_stop -> scif_handle_remove_node ->
  *    scif_peer_unregister_device -> device_unregister for the host peer device
  * 4. During device_unregister remove(..) method of cosm_client is invoked which
  *    closes the COSM SCIF endpoint on the card. This results in a SCIF_DISCNCT
  *    message being sent to host SCIF. SCIF_DISCNCT message processing on the
  *    host SCIF sets the host COSM SCIF endpoint state to DISCONNECTED and wakes
  *    up the host COSM thread blocked in scif_poll(..) resulting in
  *    scif_poll(..)  returning POLLHUP.
  * 5. On the card, scif_peer_release_dev is next called which results in an
  *    SCIF_EXIT message being sent to the host and after receiving the
  *    SCIF_EXIT_ACK from the host the peer device teardown on the card is
  *    complete.
  * 6. As part of the SCIF_EXIT message processing on the host, host sends a
  *    SCIF_REMOVE_NODE to itself corresponding to the card being removed. This
  *    starts a similar SCIF peer device teardown sequence on the host
  *    corresponding to the card being shut down.
  *
  * Card reset
  * ----------
  * The case of interest here is when the card has not been previously shut down
  * since most of the steps below are skipped in that case:

  * 1. cosm_stop(..) invokes hw_ops->stop(..) method of the base PCIe driver
  *    which unregisters the SCIF HW device resulting in scif_remove(..) being
  *    called on the host.
  * 2. scif_remove(..) calls scif_disconnect_node(..) which results in a
  *    SCIF_EXIT message being sent to the card.
  * 3. The card executes scif_stop() as part of SCIF_EXIT message
  *    processing. This results in the COSM endpoint on the card being closed and
  *    the SCIF host peer device on the card getting unregistered similar to
  *    steps 3, 4 and 5 for the card shutdown case above. scif_poll(..) on the
  *    host returns POLLHUP as a result.
  * 4. On the host, card peer device unregister and SCIF HW remove(..) also
  *    subsequently complete.
  *
  * Card crash
  * ----------
  * If a reset is issued after the card has crashed, there is no SCIF_DISCNT
  * message from the card which would result in scif_poll(..) returning
  * POLLHUP. In this case when the host SCIF driver sends a SCIF_REMOVE_NODE
  * message to itself resulting in the card SCIF peer device being unregistered,
  * this results in a scif_peer_release_dev -> scif_cleanup_scifdev->
  * scif_invalidate_ep call sequence which sets the endpoint state to
  * DISCONNECTED and results in scif_poll(..) returning POLLHUP.
  */

 #define COSM_SCIF_BACKLOG 16
 #define COSM_HEARTBEAT_CHECK_DELTA_SEC 10
 #define COSM_HEARTBEAT_TIMEOUT_SEC \
 		(COSM_HEARTBEAT_SEND_SEC + COSM_HEARTBEAT_CHECK_DELTA_SEC)
 #define COSM_HEARTBEAT_TIMEOUT_MSEC (COSM_HEARTBEAT_TIMEOUT_SEC * MSEC_PER_SEC)

 static struct task_struct *server_thread;
 static scif_epd_t listen_epd;

 /* Publish MIC card's shutdown status to user space MIC daemon */
 static void cosm_update_mic_status(struct cosm_device *cdev)
 {
 	if (cdev->shutdown_status_int != MIC_NOP) {
 		cosm_set_shutdown_status(cdev, cdev->shutdown_status_int);
 		cdev->shutdown_status_int = MIC_NOP;
 	}
 }

 /* Store MIC card's shutdown status internally when it is received */
 static void cosm_shutdown_status_int(struct cosm_device *cdev,
 				     enum mic_status shutdown_status)
 {
 	switch (shutdown_status) {
 	case MIC_HALTED:
 	case MIC_POWER_OFF:
 	case MIC_RESTART:
 	case MIC_CRASHED:
 		break;
 	default:
 		dev_err(&cdev->dev, "%s %d Unexpected shutdown_status %d\n",
 			__func__, __LINE__, shutdown_status);
 		return;
 	};
 	cdev->shutdown_status_int = shutdown_status;
 	cdev->heartbeat_watchdog_enable = false;

 	if (cdev->state != MIC_SHUTTING_DOWN)
 		cosm_set_state(cdev, MIC_SHUTTING_DOWN);
 }

 /* Non-blocking recv. Read and process all available messages */
 static void cosm_scif_recv(struct cosm_device *cdev)
 {
 	struct cosm_msg msg;
 	int rc;

 	while (1) {
 		rc = scif_recv(cdev->epd, &msg, sizeof(msg), 0);
 		if (!rc) {
 			break;
 		} else if (rc < 0) {
 			dev_dbg(&cdev->dev, "%s: %d rc %d\n",
 				__func__, __LINE__, rc);
 			break;
 		}
 		dev_dbg(&cdev->dev, "%s: %d rc %d id 0x%llx\n",
 			__func__, __LINE__, rc, msg.id);

 		switch (msg.id) {
 		case COSM_MSG_SHUTDOWN_STATUS:
 			cosm_shutdown_status_int(cdev, msg.shutdown_status);
 			break;
 		case COSM_MSG_HEARTBEAT:
 			/* Nothing to do, heartbeat only unblocks scif_poll */
 			break;
 		default:
 			dev_err(&cdev->dev, "%s: %d unknown msg.id %lld\n",
 				__func__, __LINE__, msg.id);
 			break;
 		}
 	}
 }

 /* Publish crashed status for this MIC card */
 static void cosm_set_crashed(struct cosm_device *cdev)
 {
 	dev_err(&cdev->dev, "node alive timeout\n");
 	cosm_shutdown_status_int(cdev, MIC_CRASHED);
 	cosm_update_mic_status(cdev);
 }

 /* Send host time to the MIC card to sync system time between host and MIC */
 static void cosm_send_time(struct cosm_device *cdev)
 {
 	struct cosm_msg msg = { .id = COSM_MSG_SYNC_TIME };
 	int rc;

 	getnstimeofday64(&msg.timespec);
 	rc = scif_send(cdev->epd, &msg, sizeof(msg), SCIF_SEND_BLOCK);
 	if (rc < 0)
 		dev_err(&cdev->dev, "%s %d scif_send failed rc %d\n",
 			__func__, __LINE__, rc);
 }

 /*
  * Close this cosm_device's endpoint after its peer endpoint on the card has
  * been closed. In all cases except MIC card crash POLLHUP on the host is
  * triggered by the client's endpoint being closed.
  */
 static void cosm_scif_close(struct cosm_device *cdev)
 {
 	/*
 	 * Because SHUTDOWN_STATUS message is sent by the MIC cards in the
 	 * reboot notifier when shutdown is still not complete, we notify mpssd
 	 * to reset the card when SCIF endpoint is closed.
 	 */
 	cosm_update_mic_status(cdev);
 	scif_close(cdev->epd);
 	cdev->epd = NULL;
 	dev_dbg(&cdev->dev, "%s %d\n", __func__, __LINE__);
 }

 /*
  * Set card state to ONLINE when a new SCIF connection from a MIC card is
  * received. Normally the state is BOOTING when the connection comes in, but can
  * be ONLINE if cosm_client driver on the card was unloaded and then reloaded.
  */
 static int cosm_set_online(struct cosm_device *cdev)
 {
 	int rc = 0;

 	if (MIC_BOOTING == cdev->state || MIC_ONLINE == cdev->state) {
 		cdev->heartbeat_watchdog_enable = cdev->sysfs_heartbeat_enable;
 		cdev->epd = cdev->newepd;
 		if (cdev->state == MIC_BOOTING)
 			cosm_set_state(cdev, MIC_ONLINE);
 		cosm_send_time(cdev);
 		dev_dbg(&cdev->dev, "%s %d\n", __func__, __LINE__);
 	} else {
 		dev_warn(&cdev->dev, "%s %d not going online in state: %s\n",
 			 __func__, __LINE__, cosm_state_string[cdev->state]);
 		rc = -EINVAL;
 	}
 	/* Drop reference acquired by bus_find_device in the server thread */
 	put_device(&cdev->dev);
 	return rc;
 }

 /*
  * Work function for handling work for a SCIF connection from a particular MIC
  * card. It first sets the card state to ONLINE and then calls scif_poll to
  * block on activity such as incoming messages on the SCIF endpoint. When the
  * endpoint is closed, the work function exits, completing its life cycle, from
  * MIC card boot to card shutdown/reset/crash.
  */
 void cosm_scif_work(struct work_struct *work)
 {
 	struct cosm_device *cdev = container_of(work, struct cosm_device,
 						scif_work);
 	struct scif_pollepd pollepd;
 	int rc;

 	mutex_lock(&cdev->cosm_mutex);
 	if (cosm_set_online(cdev))
 		goto exit;

 	while (1) {
 		pollepd.epd = cdev->epd;
 		pollepd.events = POLLIN;

 		/* Drop the mutex before blocking in scif_poll(..) */
 		mutex_unlock(&cdev->cosm_mutex);
 		/* poll(..) with timeout on our endpoint */
 		rc = scif_poll(&pollepd, 1, COSM_HEARTBEAT_TIMEOUT_MSEC);
 		mutex_lock(&cdev->cosm_mutex);
 		if (rc < 0) {
 			dev_err(&cdev->dev, "%s %d scif_poll rc %d\n",
 				__func__, __LINE__, rc);
 			continue;
 		}

 		/* There is a message from the card */
 		if (pollepd.revents & POLLIN)
 			cosm_scif_recv(cdev);

 		/* The peer endpoint is closed or this endpoint disconnected */
 		if (pollepd.revents & POLLHUP) {
 			cosm_scif_close(cdev);
 			break;
 		}

 		/* Did we timeout from poll? */
 		if (!rc && cdev->heartbeat_watchdog_enable)
 			cosm_set_crashed(cdev);
 	}
 exit:
 	dev_dbg(&cdev->dev, "%s %d exiting\n", __func__, __LINE__);
 	mutex_unlock(&cdev->cosm_mutex);
 }

 /*
  * COSM SCIF server thread function. Accepts incoming SCIF connections from MIC
  * cards, finds the correct cosm_device to associate that connection with and
  * schedules individual work items for each MIC card.
  */
 static int cosm_scif_server(void *unused)
 {
 	struct cosm_device *cdev;
 	scif_epd_t newepd;
 	struct scif_port_id port_id;
 	int rc;

 	allow_signal(SIGKILL);

 	while (!kthread_should_stop()) {
 		rc = scif_accept(listen_epd, &port_id, &newepd,
 				 SCIF_ACCEPT_SYNC);
 		if (rc < 0) {
 			if (-ERESTARTSYS != rc)
 				pr_err("%s %d rc %d\n", __func__, __LINE__, rc);
 			continue;
 		}

 		/*
 		 * Associate the incoming connection with a particular
 		 * cosm_device, COSM device ID == SCIF node ID - 1
 		 */
 		cdev = cosm_find_cdev_by_id(port_id.node - 1);
 		if (!cdev)
 			continue;
 		cdev->newepd = newepd;
 		schedule_work(&cdev->scif_work);
 	}

 	pr_debug("%s %d Server thread stopped\n", __func__, __LINE__);
 	return 0;
 }

 static int cosm_scif_listen(void)
 {
 	int rc;

 	listen_epd = scif_open();
 	if (!listen_epd) {
 		pr_err("%s %d scif_open failed\n", __func__, __LINE__);
 		return -ENOMEM;
 	}

 	rc = scif_bind(listen_epd, SCIF_COSM_LISTEN_PORT);
 	if (rc < 0) {
 		pr_err("%s %d scif_bind failed rc %d\n",
 		       __func__, __LINE__, rc);
 		goto err;
 	}

 	rc = scif_listen(listen_epd, COSM_SCIF_BACKLOG);
 	if (rc < 0) {
 		pr_err("%s %d scif_listen rc %d\n", __func__, __LINE__, rc);
 		goto err;
 	}
 	pr_debug("%s %d listen_epd set up\n", __func__, __LINE__);
 	return 0;
 err:
 	scif_close(listen_epd);
 	listen_epd = NULL;
 	return rc;
 }

 static void cosm_scif_listen_exit(void)
 {
 	pr_debug("%s %d closing listen_epd\n", __func__, __LINE__);
 	if (listen_epd) {
 		scif_close(listen_epd);
 		listen_epd = NULL;
 	}
 }

 /*
  * Create a listening SCIF endpoint and a server kthread which accepts incoming
  * SCIF connections from MIC cards
  */
 int cosm_scif_init(void)
 {
 	int rc = cosm_scif_listen();

 	if (rc) {
 		pr_err("%s %d cosm_scif_listen rc %d\n",
 		       __func__, __LINE__, rc);
 		goto err;
 	}

 	server_thread = kthread_run(cosm_scif_server, NULL, "cosm_server");
 	if (IS_ERR(server_thread)) {
 		rc = PTR_ERR(server_thread);
 		pr_err("%s %d kthread_run rc %d\n", __func__, __LINE__, rc);
 		goto listen_exit;
 	}
 	return 0;
 listen_exit:
 	cosm_scif_listen_exit();
 err:
 	return rc;
 }

 /* Stop the running server thread and close the listening SCIF endpoint */
 void cosm_scif_exit(void)
 {
 	int rc;

 	if (!IS_ERR_OR_NULL(server_thread)) {
 		rc = send_sig(SIGKILL, server_thread, 0);
 		if (rc) {
 			pr_err("%s %d send_sig rc %d\n",
 			       __func__, __LINE__, rc);
 			return;
 		}
 		kthread_stop(server_thread);
 	}

 	cosm_scif_listen_exit();
 }
	/*
	* Intel MIC Platform Software Stack (MPSS)
	*
	* Copyright(c) 2015 Intel Corporation.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License, version 2, as
	* published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* General Public License for more details.
	*
	* The full GNU General Public License is included in this distribution in
	* the file called "COPYING".
	*
	* Intel MIC Coprocessor State Management (COSM) Driver
	*
	*/
	#include <linux/kthread.h>
	#include "cosm_main.h"

	/*
	* The COSM driver uses SCIF to communicate between the management node and the
	* MIC cards. SCIF is used to (a) Send a shutdown command to the card (b)
	* receive a shutdown status back from the card upon completion of shutdown and
	* (c) receive periodic heartbeat messages from the card used to deduce if the
	* card has crashed.
	*
	* A COSM server consisting of a SCIF listening endpoint waits for incoming
	* connections from the card. Upon acceptance of the connection, a separate
	* work-item is scheduled to handle SCIF message processing for that card. The
	* life-time of this work-item is therefore the time from which the connection
	* from a card is accepted to the time at which the connection is closed. A new
	* work-item starts each time the card boots and is alive till the card (a)
	* shuts down (b) is reset (c) crashes (d) cosm_client driver on the card is
	* unloaded.
	*
	* From the point of view of COSM interactions with SCIF during card
	* shutdown, reset and crash are as follows:
	*
	* Card shutdown
	* -------------
	* 1. COSM client on the card invokes orderly_poweroff() in response to SHUTDOWN
	* message from the host.
	* 2. Card driver shutdown callback invokes scif_unregister_device(..) resulting
	* in scif_remove(..) getting called on the card
	* 3. scif_remove -> scif_stop -> scif_handle_remove_node ->
	* scif_peer_unregister_device -> device_unregister for the host peer device
	* 4. During device_unregister remove(..) method of cosm_client is invoked which
	* closes the COSM SCIF endpoint on the card. This results in a SCIF_DISCNCT
	* message being sent to host SCIF. SCIF_DISCNCT message processing on the
	* host SCIF sets the host COSM SCIF endpoint state to DISCONNECTED and wakes
	* up the host COSM thread blocked in scif_poll(..) resulting in
	* scif_poll(..) returning POLLHUP.
	* 5. On the card, scif_peer_release_dev is next called which results in an
	* SCIF_EXIT message being sent to the host and after receiving the
	* SCIF_EXIT_ACK from the host the peer device teardown on the card is
	* complete.
	* 6. As part of the SCIF_EXIT message processing on the host, host sends a
	* SCIF_REMOVE_NODE to itself corresponding to the card being removed. This
	* starts a similar SCIF peer device teardown sequence on the host
	* corresponding to the card being shut down.
	*
	* Card reset
	* ----------
	* The case of interest here is when the card has not been previously shut down
	* since most of the steps below are skipped in that case:

	* 1. cosm_stop(..) invokes hw_ops->stop(..) method of the base PCIe driver
	* which unregisters the SCIF HW device resulting in scif_remove(..) being
	* called on the host.
	* 2. scif_remove(..) calls scif_disconnect_node(..) which results in a
	* SCIF_EXIT message being sent to the card.
	* 3. The card executes scif_stop() as part of SCIF_EXIT message
	* processing. This results in the COSM endpoint on the card being closed and
	* the SCIF host peer device on the card getting unregistered similar to
	* steps 3, 4 and 5 for the card shutdown case above. scif_poll(..) on the
	* host returns POLLHUP as a result.
	* 4. On the host, card peer device unregister and SCIF HW remove(..) also
	* subsequently complete.
	*
	* Card crash
	* ----------
	* If a reset is issued after the card has crashed, there is no SCIF_DISCNT
	* message from the card which would result in scif_poll(..) returning
	* POLLHUP. In this case when the host SCIF driver sends a SCIF_REMOVE_NODE
	* message to itself resulting in the card SCIF peer device being unregistered,
	* this results in a scif_peer_release_dev -> scif_cleanup_scifdev->
	* scif_invalidate_ep call sequence which sets the endpoint state to
	* DISCONNECTED and results in scif_poll(..) returning POLLHUP.
	*/

	#define COSM_SCIF_BACKLOG 16
	#define COSM_HEARTBEAT_CHECK_DELTA_SEC 10
	#define COSM_HEARTBEAT_TIMEOUT_SEC \
	(COSM_HEARTBEAT_SEND_SEC + COSM_HEARTBEAT_CHECK_DELTA_SEC)
	#define COSM_HEARTBEAT_TIMEOUT_MSEC (COSM_HEARTBEAT_TIMEOUT_SEC * MSEC_PER_SEC)

	static struct task_struct *server_thread;
	static scif_epd_t listen_epd;

	/* Publish MIC card's shutdown status to user space MIC daemon */
	static void cosm_update_mic_status(struct cosm_device *cdev)
	{
	if (cdev->shutdown_status_int != MIC_NOP) {
	cosm_set_shutdown_status(cdev, cdev->shutdown_status_int);
	cdev->shutdown_status_int = MIC_NOP;
	}
	}

	/* Store MIC card's shutdown status internally when it is received */
	static void cosm_shutdown_status_int(struct cosm_device *cdev,
	enum mic_status shutdown_status)
	{
	switch (shutdown_status) {
	case MIC_HALTED:
	case MIC_POWER_OFF:
	case MIC_RESTART:
	case MIC_CRASHED:
	break;
	default:
	dev_err(&cdev->dev, "%s %d Unexpected shutdown_status %d\n",
	__func__, __LINE__, shutdown_status);
	return;
	};
	cdev->shutdown_status_int = shutdown_status;
	cdev->heartbeat_watchdog_enable = false;

	if (cdev->state != MIC_SHUTTING_DOWN)
	cosm_set_state(cdev, MIC_SHUTTING_DOWN);
	}

	/* Non-blocking recv. Read and process all available messages */
	static void cosm_scif_recv(struct cosm_device *cdev)
	{
	struct cosm_msg msg;
	int rc;

	while (1) {
	rc = scif_recv(cdev->epd, &msg, sizeof(msg), 0);
	if (!rc) {
	break;
	} else if (rc < 0) {
	dev_dbg(&cdev->dev, "%s: %d rc %d\n",
	__func__, __LINE__, rc);
	break;
	}
	dev_dbg(&cdev->dev, "%s: %d rc %d id 0x%llx\n",
	__func__, __LINE__, rc, msg.id);

	switch (msg.id) {
	case COSM_MSG_SHUTDOWN_STATUS:
	cosm_shutdown_status_int(cdev, msg.shutdown_status);
	break;
	case COSM_MSG_HEARTBEAT:
	/* Nothing to do, heartbeat only unblocks scif_poll */
	break;
	default:
	dev_err(&cdev->dev, "%s: %d unknown msg.id %lld\n",
	__func__, __LINE__, msg.id);
	break;
	}
	}
	}

	/* Publish crashed status for this MIC card */
	static void cosm_set_crashed(struct cosm_device *cdev)
	{
	dev_err(&cdev->dev, "node alive timeout\n");
	cosm_shutdown_status_int(cdev, MIC_CRASHED);
	cosm_update_mic_status(cdev);
	}

	/* Send host time to the MIC card to sync system time between host and MIC */
	static void cosm_send_time(struct cosm_device *cdev)
	{
	struct cosm_msg msg = { .id = COSM_MSG_SYNC_TIME };
	int rc;

	getnstimeofday64(&msg.timespec);
	rc = scif_send(cdev->epd, &msg, sizeof(msg), SCIF_SEND_BLOCK);
	if (rc < 0)
	dev_err(&cdev->dev, "%s %d scif_send failed rc %d\n",
	__func__, __LINE__, rc);
	}

	/*
	* Close this cosm_device's endpoint after its peer endpoint on the card has
	* been closed. In all cases except MIC card crash POLLHUP on the host is
	* triggered by the client's endpoint being closed.
	*/
	static void cosm_scif_close(struct cosm_device *cdev)
	{
	/*
	* Because SHUTDOWN_STATUS message is sent by the MIC cards in the
	* reboot notifier when shutdown is still not complete, we notify mpssd
	* to reset the card when SCIF endpoint is closed.
	*/
	cosm_update_mic_status(cdev);
	scif_close(cdev->epd);
	cdev->epd = NULL;
	dev_dbg(&cdev->dev, "%s %d\n", __func__, __LINE__);
	}

	/*
	* Set card state to ONLINE when a new SCIF connection from a MIC card is
	* received. Normally the state is BOOTING when the connection comes in, but can
	* be ONLINE if cosm_client driver on the card was unloaded and then reloaded.
	*/
	static int cosm_set_online(struct cosm_device *cdev)
	{
	int rc = 0;

	if (MIC_BOOTING == cdev->state \|\| MIC_ONLINE == cdev->state) {
	cdev->heartbeat_watchdog_enable = cdev->sysfs_heartbeat_enable;
	cdev->epd = cdev->newepd;
	if (cdev->state == MIC_BOOTING)
	cosm_set_state(cdev, MIC_ONLINE);
	cosm_send_time(cdev);
	dev_dbg(&cdev->dev, "%s %d\n", __func__, __LINE__);
	} else {
	dev_warn(&cdev->dev, "%s %d not going online in state: %s\n",
	__func__, __LINE__, cosm_state_string[cdev->state]);
	rc = -EINVAL;
	}
	/* Drop reference acquired by bus_find_device in the server thread */
	put_device(&cdev->dev);
	return rc;
	}

	/*
	* Work function for handling work for a SCIF connection from a particular MIC
	* card. It first sets the card state to ONLINE and then calls scif_poll to
	* block on activity such as incoming messages on the SCIF endpoint. When the
	* endpoint is closed, the work function exits, completing its life cycle, from
	* MIC card boot to card shutdown/reset/crash.
	*/
	void cosm_scif_work(struct work_struct *work)
	{
	struct cosm_device *cdev = container_of(work, struct cosm_device,
	scif_work);
	struct scif_pollepd pollepd;
	int rc;

	mutex_lock(&cdev->cosm_mutex);
	if (cosm_set_online(cdev))
	goto exit;

	while (1) {
	pollepd.epd = cdev->epd;
	pollepd.events = POLLIN;

	/* Drop the mutex before blocking in scif_poll(..) */
	mutex_unlock(&cdev->cosm_mutex);
	/* poll(..) with timeout on our endpoint */
	rc = scif_poll(&pollepd, 1, COSM_HEARTBEAT_TIMEOUT_MSEC);
	mutex_lock(&cdev->cosm_mutex);
	if (rc < 0) {
	dev_err(&cdev->dev, "%s %d scif_poll rc %d\n",
	__func__, __LINE__, rc);
	continue;
	}

	/* There is a message from the card */
	if (pollepd.revents & POLLIN)
	cosm_scif_recv(cdev);

	/* The peer endpoint is closed or this endpoint disconnected */
	if (pollepd.revents & POLLHUP) {
	cosm_scif_close(cdev);
	break;
	}

	/* Did we timeout from poll? */
	if (!rc && cdev->heartbeat_watchdog_enable)
	cosm_set_crashed(cdev);
	}
	exit:
	dev_dbg(&cdev->dev, "%s %d exiting\n", __func__, __LINE__);
	mutex_unlock(&cdev->cosm_mutex);
	}

	/*
	* COSM SCIF server thread function. Accepts incoming SCIF connections from MIC
	* cards, finds the correct cosm_device to associate that connection with and
	* schedules individual work items for each MIC card.
	*/
	static int cosm_scif_server(void *unused)
	{
	struct cosm_device *cdev;
	scif_epd_t newepd;
	struct scif_port_id port_id;
	int rc;

	allow_signal(SIGKILL);

	while (!kthread_should_stop()) {
	rc = scif_accept(listen_epd, &port_id, &newepd,
	SCIF_ACCEPT_SYNC);
	if (rc < 0) {
	if (-ERESTARTSYS != rc)
	pr_err("%s %d rc %d\n", __func__, __LINE__, rc);
	continue;
	}

	/*
	* Associate the incoming connection with a particular
	* cosm_device, COSM device ID == SCIF node ID - 1
	*/
	cdev = cosm_find_cdev_by_id(port_id.node - 1);
	if (!cdev)
	continue;
	cdev->newepd = newepd;
	schedule_work(&cdev->scif_work);
	}

	pr_debug("%s %d Server thread stopped\n", __func__, __LINE__);
	return 0;
	}

	static int cosm_scif_listen(void)
	{
	int rc;

	listen_epd = scif_open();
	if (!listen_epd) {
	pr_err("%s %d scif_open failed\n", __func__, __LINE__);
	return -ENOMEM;
	}

	rc = scif_bind(listen_epd, SCIF_COSM_LISTEN_PORT);
	if (rc < 0) {
	pr_err("%s %d scif_bind failed rc %d\n",
	__func__, __LINE__, rc);
	goto err;
	}

	rc = scif_listen(listen_epd, COSM_SCIF_BACKLOG);
	if (rc < 0) {
	pr_err("%s %d scif_listen rc %d\n", __func__, __LINE__, rc);
	goto err;
	}
	pr_debug("%s %d listen_epd set up\n", __func__, __LINE__);
	return 0;
	err:
	scif_close(listen_epd);
	listen_epd = NULL;
	return rc;
	}

	static void cosm_scif_listen_exit(void)
	{
	pr_debug("%s %d closing listen_epd\n", __func__, __LINE__);
	if (listen_epd) {
	scif_close(listen_epd);
	listen_epd = NULL;
	}
	}

	/*
	* Create a listening SCIF endpoint and a server kthread which accepts incoming
	* SCIF connections from MIC cards
	*/
	int cosm_scif_init(void)
	{
	int rc = cosm_scif_listen();

	if (rc) {
	pr_err("%s %d cosm_scif_listen rc %d\n",
	__func__, __LINE__, rc);
	goto err;
	}

	server_thread = kthread_run(cosm_scif_server, NULL, "cosm_server");
	if (IS_ERR(server_thread)) {
	rc = PTR_ERR(server_thread);
	pr_err("%s %d kthread_run rc %d\n", __func__, __LINE__, rc);
	goto listen_exit;
	}
	return 0;
	listen_exit:
	cosm_scif_listen_exit();
	err:
	return rc;
	}

	/* Stop the running server thread and close the listening SCIF endpoint */
	void cosm_scif_exit(void)
	{
	int rc;

	if (!IS_ERR_OR_NULL(server_thread)) {
	rc = send_sig(SIGKILL, server_thread, 0);
	if (rc) {
	pr_err("%s %d send_sig rc %d\n",
	__func__, __LINE__, rc);
	return;
	}
	kthread_stop(server_thread);
	}

	cosm_scif_listen_exit();
	}