--- /dev/null
+/*
+ * 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();
+}
projects / platform / kernel / linux-rpi3.git / commitdiff