/*
   * 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 COSM Client Driver
   *
   */
  #include <linux/module.h>
  #include <linux/delay.h>
  #include <linux/reboot.h>
  #include <linux/kthread.h>
  #include "../cosm/cosm_main.h"
  
  #define COSM_SCIF_MAX_RETRIES 10
  #define COSM_HEARTBEAT_SEND_MSEC (COSM_HEARTBEAT_SEND_SEC * MSEC_PER_SEC)
  
  static struct task_struct *client_thread;
  static scif_epd_t client_epd;
  static struct scif_peer_dev *client_spdev;
  
  /*
   * Reboot notifier: receives shutdown status from the OS and communicates it
   * back to the COSM process on the host
   */
  static int cosm_reboot_event(struct notifier_block *this, unsigned long event,
  			     void *ptr)
  {
  	struct cosm_msg msg = { .id = COSM_MSG_SHUTDOWN_STATUS };
  	int rc;
  
  	event = (event == SYS_RESTART) ? SYSTEM_RESTART : event;
  	dev_info(&client_spdev->dev, "%s %d received event %ld
  ",
  		 __func__, __LINE__, event);
  
  	msg.shutdown_status = event;
  	rc = scif_send(client_epd, &msg, sizeof(msg), SCIF_SEND_BLOCK);
  	if (rc < 0)
  		dev_err(&client_spdev->dev, "%s %d scif_send rc %d
  ",
  			__func__, __LINE__, rc);
  
  	return NOTIFY_DONE;
  }
  
  static struct notifier_block cosm_reboot = {
  	.notifier_call  = cosm_reboot_event,
  };
  
  /* Set system time from timespec value received from the host */
  static void cosm_set_time(struct cosm_msg *msg)
  {
  	int rc = do_settimeofday64(&msg->timespec);
  
  	if (rc)
  		dev_err(&client_spdev->dev, "%s: %d settimeofday rc %d
  ",
  			__func__, __LINE__, rc);
  }
  
  /* COSM client receive message processing */
  static void cosm_client_recv(void)
  {
  	struct cosm_msg msg;
  	int rc;
  
  	while (1) {
  		rc = scif_recv(client_epd, &msg, sizeof(msg), 0);
  		if (!rc) {
  			return;
  		} else if (rc < 0) {
  			dev_err(&client_spdev->dev, "%s: %d rc %d
  ",
  				__func__, __LINE__, rc);
  			return;
  		}
  
  		dev_dbg(&client_spdev->dev, "%s: %d rc %d id 0x%llx
  ",
  			__func__, __LINE__, rc, msg.id);
  
  		switch (msg.id) {
  		case COSM_MSG_SYNC_TIME:
  			cosm_set_time(&msg);
  			break;
  		case COSM_MSG_SHUTDOWN:
  			orderly_poweroff(true);
  			break;
  		default:
  			dev_err(&client_spdev->dev, "%s: %d unknown id %lld
  ",
  				__func__, __LINE__, msg.id);
  			break;
  		}
  	}
  }
  
  /* Initiate connection to the COSM server on the host */
  static int cosm_scif_connect(void)
  {
  	struct scif_port_id port_id;
  	int i, rc;
  
  	client_epd = scif_open();
  	if (!client_epd) {
  		dev_err(&client_spdev->dev, "%s %d scif_open failed
  ",
  			__func__, __LINE__);
  		return -ENOMEM;
  	}
  
  	port_id.node = 0;
  	port_id.port = SCIF_COSM_LISTEN_PORT;
  
  	for (i = 0; i < COSM_SCIF_MAX_RETRIES; i++) {
  		rc = scif_connect(client_epd, &port_id);
  		if (rc < 0)
  			msleep(1000);
  		else
  			break;
  	}
  
  	if (rc < 0) {
  		dev_err(&client_spdev->dev, "%s %d scif_connect rc %d
  ",
  			__func__, __LINE__, rc);
  		scif_close(client_epd);
  		client_epd = NULL;
  	}
  	return rc < 0 ? rc : 0;
  }
  
  /* Close host SCIF connection */
  static void cosm_scif_connect_exit(void)
  {
  	if (client_epd) {
  		scif_close(client_epd);
  		client_epd = NULL;
  	}
  }
  
  /*
   * COSM SCIF client thread function: waits for messages from the host and sends
   * a heartbeat to the host
   */
  static int cosm_scif_client(void *unused)
  {
  	struct cosm_msg msg = { .id = COSM_MSG_HEARTBEAT };
  	struct scif_pollepd pollepd;
  	int rc;
  
  	allow_signal(SIGKILL);
  
  	while (!kthread_should_stop()) {
  		pollepd.epd = client_epd;
  		pollepd.events = POLLIN;
  
  		rc = scif_poll(&pollepd, 1, COSM_HEARTBEAT_SEND_MSEC);
  		if (rc < 0) {
  			if (-EINTR != rc)
  				dev_err(&client_spdev->dev,
  					"%s %d scif_poll rc %d
  ",
  					__func__, __LINE__, rc);
  			continue;
  		}
  
  		if (pollepd.revents & POLLIN)
  			cosm_client_recv();
  
  		msg.id = COSM_MSG_HEARTBEAT;
  		rc = scif_send(client_epd, &msg, sizeof(msg), SCIF_SEND_BLOCK);
  		if (rc < 0)
  			dev_err(&client_spdev->dev, "%s %d scif_send rc %d
  ",
  				__func__, __LINE__, rc);
  	}
  
  	dev_dbg(&client_spdev->dev, "%s %d Client thread stopped
  ",
  		__func__, __LINE__);
  	return 0;
  }
  
  static void cosm_scif_probe(struct scif_peer_dev *spdev)
  {
  	int rc;
  
  	dev_dbg(&spdev->dev, "%s %d: dnode %d
  ",
  		__func__, __LINE__, spdev->dnode);
  
  	/* We are only interested in the host with spdev->dnode == 0 */
  	if (spdev->dnode)
  		return;
  
  	client_spdev = spdev;
  	rc = cosm_scif_connect();
  	if (rc)
  		goto exit;
  
  	rc = register_reboot_notifier(&cosm_reboot);
  	if (rc) {
  		dev_err(&spdev->dev,
  			"reboot notifier registration failed rc %d
  ", rc);
  		goto connect_exit;
  	}
  
  	client_thread = kthread_run(cosm_scif_client, NULL, "cosm_client");
  	if (IS_ERR(client_thread)) {
  		rc = PTR_ERR(client_thread);
  		dev_err(&spdev->dev, "%s %d kthread_run rc %d
  ",
  			__func__, __LINE__, rc);
  		goto unreg_reboot;
  	}
  	return;
  unreg_reboot:
  	unregister_reboot_notifier(&cosm_reboot);
  connect_exit:
  	cosm_scif_connect_exit();
  exit:
  	client_spdev = NULL;
  }
  
  static void cosm_scif_remove(struct scif_peer_dev *spdev)
  {
  	int rc;
  
  	dev_dbg(&spdev->dev, "%s %d: dnode %d
  ",
  		__func__, __LINE__, spdev->dnode);
  
  	if (spdev->dnode)
  		return;
  
  	if (!IS_ERR_OR_NULL(client_thread)) {
  		rc = send_sig(SIGKILL, client_thread, 0);
  		if (rc) {
  			pr_err("%s %d send_sig rc %d
  ",
  			       __func__, __LINE__, rc);
  			return;
  		}
  		kthread_stop(client_thread);
  	}
  	unregister_reboot_notifier(&cosm_reboot);
  	cosm_scif_connect_exit();
  	client_spdev = NULL;
  }
  
  static struct scif_client scif_client_cosm = {
  	.name = KBUILD_MODNAME,
  	.probe = cosm_scif_probe,
  	.remove = cosm_scif_remove,
  };
  
  static int __init cosm_client_init(void)
  {
  	int rc = scif_client_register(&scif_client_cosm);
  
  	if (rc)
  		pr_err("scif_client_register failed rc %d
  ", rc);
  	return rc;
  }
  
  static void __exit cosm_client_exit(void)
  {
  	scif_client_unregister(&scif_client_cosm);
  }
  
  module_init(cosm_client_init);
  module_exit(cosm_client_exit);
  
  MODULE_AUTHOR("Intel Corporation");
  MODULE_DESCRIPTION("Intel(R) MIC card OS state management client driver");
  MODULE_LICENSE("GPL v2");