misc: mic: COSM client driver

The COSM client driver running on the MIC cards is implemented as a
kernel mode SCIF client. It responds to a "shutdown" message from the
host by triggering a card shutdown and also communicates the shutdown
or reboot status back the host. It is also responsible for syncing the
card time to that of the host. Because SCIF messaging cannot be used
in a panic context, the COSM client driver also periodically sends a
heartbeat SCIF message to the host thereby enabling the host to detect
card crashes.
Reviewed-by: Nikhil Rao <nikhil.rao@intel.com>
Reviewed-by: Sudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mic/cosm_client/Makefile

+#
+# Makefile - Intel MIC COSM Client Driver
+# Copyright(c) 2015, Intel Corporation.
+#
+obj-$(CONFIG_MIC_COSM) += cosm_client.o
+
+cosm_client-objs += cosm_scif_client.o

drivers/misc/mic/cosm_client/cosm_scif_client.c

+/*
+ * 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\n",
+		 __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\n",
+			__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\n",
+			__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\n",
+				__func__, __LINE__, rc);
+			return;
+		}
+
+		dev_dbg(&client_spdev->dev, "%s: %d rc %d id 0x%llx\n",
+			__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\n",
+				__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\n",
+			__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\n",
+			__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\n",
+					__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\n",
+				__func__, __LINE__, rc);
+	}
+
+	dev_dbg(&client_spdev->dev, "%s %d Client thread stopped\n",
+		__func__, __LINE__);
+	return 0;
+}
+
+static void cosm_scif_probe(struct scif_peer_dev *spdev)
+{
+	int rc;
+
+	dev_dbg(&spdev->dev, "%s %d: dnode %d\n",
+		__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\n", 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\n",
+			__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\n",
+		__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\n",
+			       __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\n", 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");