Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 810 insertions, 0 deletions

diff --git a/drivers/remoteproc/qcom_sysmon.c b/drivers/remoteproc/qcom_sysmon.c
new file mode 100644
index 0000000000..c24e4a8828
--- /dev/null
+++ b/drivers/remoteproc/qcom_sysmon.c
@@ -0,0 +1,810 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2017, Linaro Ltd.
+ */
+#include <linux/firmware.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/remoteproc/qcom_rproc.h>
+#include <linux/rpmsg.h>
+
+#include "qcom_common.h"
+
+static BLOCKING_NOTIFIER_HEAD(sysmon_notifiers);
+
+struct qcom_sysmon {
+	struct rproc_subdev subdev;
+	struct rproc *rproc;
+
+	int state;
+	struct mutex state_lock;
+
+	struct list_head node;
+
+	const char *name;
+
+	int shutdown_irq;
+	int ssctl_version;
+	int ssctl_instance;
+
+	struct notifier_block nb;
+
+	struct device *dev;
+
+	struct rpmsg_endpoint *ept;
+	struct completion comp;
+	struct completion ind_comp;
+	struct completion shutdown_comp;
+	struct completion ssctl_comp;
+	struct mutex lock;
+
+	bool ssr_ack;
+	bool shutdown_acked;
+
+	struct qmi_handle qmi;
+	struct sockaddr_qrtr ssctl;
+};
+
+enum {
+	SSCTL_SSR_EVENT_BEFORE_POWERUP,
+	SSCTL_SSR_EVENT_AFTER_POWERUP,
+	SSCTL_SSR_EVENT_BEFORE_SHUTDOWN,
+	SSCTL_SSR_EVENT_AFTER_SHUTDOWN,
+};
+
+static const char * const sysmon_state_string[] = {
+	[SSCTL_SSR_EVENT_BEFORE_POWERUP]	= "before_powerup",
+	[SSCTL_SSR_EVENT_AFTER_POWERUP]		= "after_powerup",
+	[SSCTL_SSR_EVENT_BEFORE_SHUTDOWN]	= "before_shutdown",
+	[SSCTL_SSR_EVENT_AFTER_SHUTDOWN]	= "after_shutdown",
+};
+
+struct sysmon_event {
+	const char *subsys_name;
+	u32 ssr_event;
+};
+
+static DEFINE_MUTEX(sysmon_lock);
+static LIST_HEAD(sysmon_list);
+
+/**
+ * sysmon_send_event() - send notification of other remote's SSR event
+ * @sysmon:	sysmon context
+ * @event:	sysmon event context
+ */
+static void sysmon_send_event(struct qcom_sysmon *sysmon,
+			      const struct sysmon_event *event)
+{
+	char req[50];
+	int len;
+	int ret;
+
+	len = snprintf(req, sizeof(req), "ssr:%s:%s", event->subsys_name,
+		       sysmon_state_string[event->ssr_event]);
+	if (len >= sizeof(req))
+		return;
+
+	mutex_lock(&sysmon->lock);
+	reinit_completion(&sysmon->comp);
+	sysmon->ssr_ack = false;
+
+	ret = rpmsg_send(sysmon->ept, req, len);
+	if (ret < 0) {
+		dev_err(sysmon->dev, "failed to send sysmon event\n");
+		goto out_unlock;
+	}
+
+	ret = wait_for_completion_timeout(&sysmon->comp,
+					  msecs_to_jiffies(5000));
+	if (!ret) {
+		dev_err(sysmon->dev, "timeout waiting for sysmon ack\n");
+		goto out_unlock;
+	}
+
+	if (!sysmon->ssr_ack)
+		dev_err(sysmon->dev, "unexpected response to sysmon event\n");
+
+out_unlock:
+	mutex_unlock(&sysmon->lock);
+}
+
+/**
+ * sysmon_request_shutdown() - request graceful shutdown of remote
+ * @sysmon:	sysmon context
+ *
+ * Return: boolean indicator of the remote processor acking the request
+ */
+static bool sysmon_request_shutdown(struct qcom_sysmon *sysmon)
+{
+	char *req = "ssr:shutdown";
+	bool acked = false;
+	int ret;
+
+	mutex_lock(&sysmon->lock);
+	reinit_completion(&sysmon->comp);
+	sysmon->ssr_ack = false;
+
+	ret = rpmsg_send(sysmon->ept, req, strlen(req) + 1);
+	if (ret < 0) {
+		dev_err(sysmon->dev, "send sysmon shutdown request failed\n");
+		goto out_unlock;
+	}
+
+	ret = wait_for_completion_timeout(&sysmon->comp,
+					  msecs_to_jiffies(5000));
+	if (!ret) {
+		dev_err(sysmon->dev, "timeout waiting for sysmon ack\n");
+		goto out_unlock;
+	}
+
+	if (!sysmon->ssr_ack)
+		dev_err(sysmon->dev,
+			"unexpected response to sysmon shutdown request\n");
+	else
+		acked = true;
+
+out_unlock:
+	mutex_unlock(&sysmon->lock);
+
+	return acked;
+}
+
+static int sysmon_callback(struct rpmsg_device *rpdev, void *data, int count,
+			   void *priv, u32 addr)
+{
+	struct qcom_sysmon *sysmon = priv;
+	const char *ssr_ack = "ssr:ack";
+	const int ssr_ack_len = strlen(ssr_ack) + 1;
+
+	if (!sysmon)
+		return -EINVAL;
+
+	if (count >= ssr_ack_len && !memcmp(data, ssr_ack, ssr_ack_len))
+		sysmon->ssr_ack = true;
+
+	complete(&sysmon->comp);
+
+	return 0;
+}
+
+#define SSCTL_SHUTDOWN_REQ		0x21
+#define SSCTL_SHUTDOWN_READY_IND	0x21
+#define SSCTL_SUBSYS_EVENT_REQ		0x23
+
+#define SSCTL_MAX_MSG_LEN		7
+
+#define SSCTL_SUBSYS_NAME_LENGTH	15
+
+enum {
+	SSCTL_SSR_EVENT_FORCED,
+	SSCTL_SSR_EVENT_GRACEFUL,
+};
+
+struct ssctl_shutdown_resp {
+	struct qmi_response_type_v01 resp;
+};
+
+static const struct qmi_elem_info ssctl_shutdown_resp_ei[] = {
+	{
+		.data_type	= QMI_STRUCT,
+		.elem_len	= 1,
+		.elem_size	= sizeof(struct qmi_response_type_v01),
+		.array_type	= NO_ARRAY,
+		.tlv_type	= 0x02,
+		.offset		= offsetof(struct ssctl_shutdown_resp, resp),
+		.ei_array	= qmi_response_type_v01_ei,
+	},
+	{}
+};
+
+struct ssctl_subsys_event_req {
+	u8 subsys_name_len;
+	char subsys_name[SSCTL_SUBSYS_NAME_LENGTH];
+	u32 event;
+	u8 evt_driven_valid;
+	u32 evt_driven;
+};
+
+static const struct qmi_elem_info ssctl_subsys_event_req_ei[] = {
+	{
+		.data_type	= QMI_DATA_LEN,
+		.elem_len	= 1,
+		.elem_size	= sizeof(uint8_t),
+		.array_type	= NO_ARRAY,
+		.tlv_type	= 0x01,
+		.offset		= offsetof(struct ssctl_subsys_event_req,
+					   subsys_name_len),
+		.ei_array	= NULL,
+	},
+	{
+		.data_type	= QMI_UNSIGNED_1_BYTE,
+		.elem_len	= SSCTL_SUBSYS_NAME_LENGTH,
+		.elem_size	= sizeof(char),
+		.array_type	= VAR_LEN_ARRAY,
+		.tlv_type	= 0x01,
+		.offset		= offsetof(struct ssctl_subsys_event_req,
+					   subsys_name),
+		.ei_array	= NULL,
+	},
+	{
+		.data_type	= QMI_SIGNED_4_BYTE_ENUM,
+		.elem_len	= 1,
+		.elem_size	= sizeof(uint32_t),
+		.array_type	= NO_ARRAY,
+		.tlv_type	= 0x02,
+		.offset		= offsetof(struct ssctl_subsys_event_req,
+					   event),
+		.ei_array	= NULL,
+	},
+	{
+		.data_type	= QMI_OPT_FLAG,
+		.elem_len	= 1,
+		.elem_size	= sizeof(uint8_t),
+		.array_type	= NO_ARRAY,
+		.tlv_type	= 0x10,
+		.offset		= offsetof(struct ssctl_subsys_event_req,
+					   evt_driven_valid),
+		.ei_array	= NULL,
+	},
+	{
+		.data_type	= QMI_SIGNED_4_BYTE_ENUM,
+		.elem_len	= 1,
+		.elem_size	= sizeof(uint32_t),
+		.array_type	= NO_ARRAY,
+		.tlv_type	= 0x10,
+		.offset		= offsetof(struct ssctl_subsys_event_req,
+					   evt_driven),
+		.ei_array	= NULL,
+	},
+	{}
+};
+
+struct ssctl_subsys_event_resp {
+	struct qmi_response_type_v01 resp;
+};
+
+static const struct qmi_elem_info ssctl_subsys_event_resp_ei[] = {
+	{
+		.data_type	= QMI_STRUCT,
+		.elem_len	= 1,
+		.elem_size	= sizeof(struct qmi_response_type_v01),
+		.array_type	= NO_ARRAY,
+		.tlv_type	= 0x02,
+		.offset		= offsetof(struct ssctl_subsys_event_resp,
+					   resp),
+		.ei_array	= qmi_response_type_v01_ei,
+	},
+	{}
+};
+
+static const struct qmi_elem_info ssctl_shutdown_ind_ei[] = {
+	{}
+};
+
+static void sysmon_ind_cb(struct qmi_handle *qmi, struct sockaddr_qrtr *sq,
+			  struct qmi_txn *txn, const void *data)
+{
+	struct qcom_sysmon *sysmon = container_of(qmi, struct qcom_sysmon, qmi);
+
+	complete(&sysmon->ind_comp);
+}
+
+static const struct qmi_msg_handler qmi_indication_handler[] = {
+	{
+		.type = QMI_INDICATION,
+		.msg_id = SSCTL_SHUTDOWN_READY_IND,
+		.ei = ssctl_shutdown_ind_ei,
+		.decoded_size = 0,
+		.fn = sysmon_ind_cb
+	},
+	{}
+};
+
+static bool ssctl_request_shutdown_wait(struct qcom_sysmon *sysmon)
+{
+	int ret;
+
+	ret = wait_for_completion_timeout(&sysmon->shutdown_comp, 10 * HZ);
+	if (ret)
+		return true;
+
+	ret = try_wait_for_completion(&sysmon->ind_comp);
+	if (ret)
+		return true;
+
+	dev_err(sysmon->dev, "timeout waiting for shutdown ack\n");
+	return false;
+}
+
+/**
+ * ssctl_request_shutdown() - request shutdown via SSCTL QMI service
+ * @sysmon:	sysmon context
+ *
+ * Return: boolean indicator of the remote processor acking the request
+ */
+static bool ssctl_request_shutdown(struct qcom_sysmon *sysmon)
+{
+	struct ssctl_shutdown_resp resp;
+	struct qmi_txn txn;
+	bool acked = false;
+	int ret;
+
+	reinit_completion(&sysmon->ind_comp);
+	reinit_completion(&sysmon->shutdown_comp);
+	ret = qmi_txn_init(&sysmon->qmi, &txn, ssctl_shutdown_resp_ei, &resp);
+	if (ret < 0) {
+		dev_err(sysmon->dev, "failed to allocate QMI txn\n");
+		return false;
+	}
+
+	ret = qmi_send_request(&sysmon->qmi, &sysmon->ssctl, &txn,
+			       SSCTL_SHUTDOWN_REQ, 0, NULL, NULL);
+	if (ret < 0) {
+		dev_err(sysmon->dev, "failed to send shutdown request\n");
+		qmi_txn_cancel(&txn);
+		return false;
+	}
+
+	ret = qmi_txn_wait(&txn, 5 * HZ);
+	if (ret < 0) {
+		dev_err(sysmon->dev, "timeout waiting for shutdown response\n");
+	} else if (resp.resp.result) {
+		dev_err(sysmon->dev, "shutdown request rejected\n");
+	} else {
+		dev_dbg(sysmon->dev, "shutdown request completed\n");
+		acked = true;
+	}
+
+	if (sysmon->shutdown_irq > 0)
+		return ssctl_request_shutdown_wait(sysmon);
+
+	return acked;
+}
+
+/**
+ * ssctl_send_event() - send notification of other remote's SSR event
+ * @sysmon:	sysmon context
+ * @event:	sysmon event context
+ */
+static void ssctl_send_event(struct qcom_sysmon *sysmon,
+			     const struct sysmon_event *event)
+{
+	struct ssctl_subsys_event_resp resp;
+	struct ssctl_subsys_event_req req;
+	struct qmi_txn txn;
+	int ret;
+
+	memset(&resp, 0, sizeof(resp));
+	ret = qmi_txn_init(&sysmon->qmi, &txn, ssctl_subsys_event_resp_ei, &resp);
+	if (ret < 0) {
+		dev_err(sysmon->dev, "failed to allocate QMI txn\n");
+		return;
+	}
+
+	memset(&req, 0, sizeof(req));
+	strscpy(req.subsys_name, event->subsys_name, sizeof(req.subsys_name));
+	req.subsys_name_len = strlen(req.subsys_name);
+	req.event = event->ssr_event;
+	req.evt_driven_valid = true;
+	req.evt_driven = SSCTL_SSR_EVENT_FORCED;
+
+	ret = qmi_send_request(&sysmon->qmi, &sysmon->ssctl, &txn,
+			       SSCTL_SUBSYS_EVENT_REQ, 40,
+			       ssctl_subsys_event_req_ei, &req);
+	if (ret < 0) {
+		dev_err(sysmon->dev, "failed to send subsystem event\n");
+		qmi_txn_cancel(&txn);
+		return;
+	}
+
+	ret = qmi_txn_wait(&txn, 5 * HZ);
+	if (ret < 0)
+		dev_err(sysmon->dev, "timeout waiting for subsystem event response\n");
+	else if (resp.resp.result)
+		dev_err(sysmon->dev, "subsystem event rejected\n");
+	else
+		dev_dbg(sysmon->dev, "subsystem event accepted\n");
+}
+
+/**
+ * ssctl_new_server() - QMI callback indicating a new service
+ * @qmi:	QMI handle
+ * @svc:	service information
+ *
+ * Return: 0 if we're interested in this service, -EINVAL otherwise.
+ */
+static int ssctl_new_server(struct qmi_handle *qmi, struct qmi_service *svc)
+{
+	struct qcom_sysmon *sysmon = container_of(qmi, struct qcom_sysmon, qmi);
+
+	switch (svc->version) {
+	case 1:
+		if (svc->instance != 0)
+			return -EINVAL;
+		if (strcmp(sysmon->name, "modem"))
+			return -EINVAL;
+		break;
+	case 2:
+		if (svc->instance != sysmon->ssctl_instance)
+			return -EINVAL;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	sysmon->ssctl_version = svc->version;
+
+	sysmon->ssctl.sq_family = AF_QIPCRTR;
+	sysmon->ssctl.sq_node = svc->node;
+	sysmon->ssctl.sq_port = svc->port;
+
+	svc->priv = sysmon;
+
+	complete(&sysmon->ssctl_comp);
+
+	return 0;
+}
+
+/**
+ * ssctl_del_server() - QMI callback indicating that @svc is removed
+ * @qmi:	QMI handle
+ * @svc:	service information
+ */
+static void ssctl_del_server(struct qmi_handle *qmi, struct qmi_service *svc)
+{
+	struct qcom_sysmon *sysmon = svc->priv;
+
+	sysmon->ssctl_version = 0;
+}
+
+static const struct qmi_ops ssctl_ops = {
+	.new_server = ssctl_new_server,
+	.del_server = ssctl_del_server,
+};
+
+static int sysmon_prepare(struct rproc_subdev *subdev)
+{
+	struct qcom_sysmon *sysmon = container_of(subdev, struct qcom_sysmon,
+						  subdev);
+	struct sysmon_event event = {
+		.subsys_name = sysmon->name,
+		.ssr_event = SSCTL_SSR_EVENT_BEFORE_POWERUP
+	};
+
+	mutex_lock(&sysmon->state_lock);
+	sysmon->state = SSCTL_SSR_EVENT_BEFORE_POWERUP;
+	blocking_notifier_call_chain(&sysmon_notifiers, 0, (void *)&event);
+	mutex_unlock(&sysmon->state_lock);
+
+	return 0;
+}
+
+/**
+ * sysmon_start() - start callback for the sysmon remoteproc subdevice
+ * @subdev:	instance of the sysmon subdevice
+ *
+ * Inform all the listners of sysmon notifications that the rproc associated
+ * to @subdev has booted up. The rproc that booted up also needs to know
+ * which rprocs are already up and running, so send start notifications
+ * on behalf of all the online rprocs.
+ */
+static int sysmon_start(struct rproc_subdev *subdev)
+{
+	struct qcom_sysmon *sysmon = container_of(subdev, struct qcom_sysmon,
+						  subdev);
+	struct qcom_sysmon *target;
+	struct sysmon_event event = {
+		.subsys_name = sysmon->name,
+		.ssr_event = SSCTL_SSR_EVENT_AFTER_POWERUP
+	};
+
+	reinit_completion(&sysmon->ssctl_comp);
+	mutex_lock(&sysmon->state_lock);
+	sysmon->state = SSCTL_SSR_EVENT_AFTER_POWERUP;
+	blocking_notifier_call_chain(&sysmon_notifiers, 0, (void *)&event);
+	mutex_unlock(&sysmon->state_lock);
+
+	mutex_lock(&sysmon_lock);
+	list_for_each_entry(target, &sysmon_list, node) {
+		mutex_lock(&target->state_lock);
+		if (target == sysmon || target->state != SSCTL_SSR_EVENT_AFTER_POWERUP) {
+			mutex_unlock(&target->state_lock);
+			continue;
+		}
+
+		event.subsys_name = target->name;
+		event.ssr_event = target->state;
+
+		if (sysmon->ssctl_version == 2)
+			ssctl_send_event(sysmon, &event);
+		else if (sysmon->ept)
+			sysmon_send_event(sysmon, &event);
+		mutex_unlock(&target->state_lock);
+	}
+	mutex_unlock(&sysmon_lock);
+
+	return 0;
+}
+
+static void sysmon_stop(struct rproc_subdev *subdev, bool crashed)
+{
+	struct qcom_sysmon *sysmon = container_of(subdev, struct qcom_sysmon, subdev);
+	struct sysmon_event event = {
+		.subsys_name = sysmon->name,
+		.ssr_event = SSCTL_SSR_EVENT_BEFORE_SHUTDOWN
+	};
+
+	sysmon->shutdown_acked = false;
+
+	mutex_lock(&sysmon->state_lock);
+	sysmon->state = SSCTL_SSR_EVENT_BEFORE_SHUTDOWN;
+	blocking_notifier_call_chain(&sysmon_notifiers, 0, (void *)&event);
+	mutex_unlock(&sysmon->state_lock);
+
+	/* Don't request graceful shutdown if we've crashed */
+	if (crashed)
+		return;
+
+	if (sysmon->ssctl_instance) {
+		if (!wait_for_completion_timeout(&sysmon->ssctl_comp, HZ / 2))
+			dev_err(sysmon->dev, "timeout waiting for ssctl service\n");
+	}
+
+	if (sysmon->ssctl_version)
+		sysmon->shutdown_acked = ssctl_request_shutdown(sysmon);
+	else if (sysmon->ept)
+		sysmon->shutdown_acked = sysmon_request_shutdown(sysmon);
+}
+
+static void sysmon_unprepare(struct rproc_subdev *subdev)
+{
+	struct qcom_sysmon *sysmon = container_of(subdev, struct qcom_sysmon,
+						  subdev);
+	struct sysmon_event event = {
+		.subsys_name = sysmon->name,
+		.ssr_event = SSCTL_SSR_EVENT_AFTER_SHUTDOWN
+	};
+
+	mutex_lock(&sysmon->state_lock);
+	sysmon->state = SSCTL_SSR_EVENT_AFTER_SHUTDOWN;
+	blocking_notifier_call_chain(&sysmon_notifiers, 0, (void *)&event);
+	mutex_unlock(&sysmon->state_lock);
+}
+
+/**
+ * sysmon_notify() - notify sysmon target of another's SSR
+ * @nb:		notifier_block associated with sysmon instance
+ * @event:	unused
+ * @data:	SSR identifier of the remote that is going down
+ */
+static int sysmon_notify(struct notifier_block *nb, unsigned long event,
+			 void *data)
+{
+	struct qcom_sysmon *sysmon = container_of(nb, struct qcom_sysmon, nb);
+	struct sysmon_event *sysmon_event = data;
+
+	/* Skip non-running rprocs and the originating instance */
+	if (sysmon->state != SSCTL_SSR_EVENT_AFTER_POWERUP ||
+	    !strcmp(sysmon_event->subsys_name, sysmon->name)) {
+		dev_dbg(sysmon->dev, "not notifying %s\n", sysmon->name);
+		return NOTIFY_DONE;
+	}
+
+	/* Only SSCTL version 2 supports SSR events */
+	if (sysmon->ssctl_version == 2)
+		ssctl_send_event(sysmon, sysmon_event);
+	else if (sysmon->ept)
+		sysmon_send_event(sysmon, sysmon_event);
+
+	return NOTIFY_DONE;
+}
+
+static irqreturn_t sysmon_shutdown_interrupt(int irq, void *data)
+{
+	struct qcom_sysmon *sysmon = data;
+
+	complete(&sysmon->shutdown_comp);
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * qcom_add_sysmon_subdev() - create a sysmon subdev for the given remoteproc
+ * @rproc:	rproc context to associate the subdev with
+ * @name:	name of this subdev, to use in SSR
+ * @ssctl_instance: instance id of the ssctl QMI service
+ *
+ * Return: A new qcom_sysmon object, or NULL on failure
+ */
+struct qcom_sysmon *qcom_add_sysmon_subdev(struct rproc *rproc,
+					   const char *name,
+					   int ssctl_instance)
+{
+	struct qcom_sysmon *sysmon;
+	int ret;
+
+	sysmon = kzalloc(sizeof(*sysmon), GFP_KERNEL);
+	if (!sysmon)
+		return ERR_PTR(-ENOMEM);
+
+	sysmon->dev = rproc->dev.parent;
+	sysmon->rproc = rproc;
+
+	sysmon->name = name;
+	sysmon->ssctl_instance = ssctl_instance;
+
+	init_completion(&sysmon->comp);
+	init_completion(&sysmon->ind_comp);
+	init_completion(&sysmon->shutdown_comp);
+	init_completion(&sysmon->ssctl_comp);
+	mutex_init(&sysmon->lock);
+	mutex_init(&sysmon->state_lock);
+
+	sysmon->shutdown_irq = of_irq_get_byname(sysmon->dev->of_node,
+						 "shutdown-ack");
+	if (sysmon->shutdown_irq < 0) {
+		if (sysmon->shutdown_irq != -ENODATA) {
+			dev_err(sysmon->dev,
+				"failed to retrieve shutdown-ack IRQ\n");
+			ret = sysmon->shutdown_irq;
+			kfree(sysmon);
+			return ERR_PTR(ret);
+		}
+	} else {
+		ret = devm_request_threaded_irq(sysmon->dev,
+						sysmon->shutdown_irq,
+						NULL, sysmon_shutdown_interrupt,
+						IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+						"q6v5 shutdown-ack", sysmon);
+		if (ret) {
+			dev_err(sysmon->dev,
+				"failed to acquire shutdown-ack IRQ\n");
+			kfree(sysmon);
+			return ERR_PTR(ret);
+		}
+	}
+
+	ret = qmi_handle_init(&sysmon->qmi, SSCTL_MAX_MSG_LEN, &ssctl_ops,
+			      qmi_indication_handler);
+	if (ret < 0) {
+		dev_err(sysmon->dev, "failed to initialize qmi handle\n");
+		kfree(sysmon);
+		return ERR_PTR(ret);
+	}
+
+	qmi_add_lookup(&sysmon->qmi, 43, 0, 0);
+
+	sysmon->subdev.prepare = sysmon_prepare;
+	sysmon->subdev.start = sysmon_start;
+	sysmon->subdev.stop = sysmon_stop;
+	sysmon->subdev.unprepare = sysmon_unprepare;
+
+	rproc_add_subdev(rproc, &sysmon->subdev);
+
+	sysmon->nb.notifier_call = sysmon_notify;
+	blocking_notifier_chain_register(&sysmon_notifiers, &sysmon->nb);
+
+	mutex_lock(&sysmon_lock);
+	list_add(&sysmon->node, &sysmon_list);
+	mutex_unlock(&sysmon_lock);
+
+	return sysmon;
+}
+EXPORT_SYMBOL_GPL(qcom_add_sysmon_subdev);
+
+/**
+ * qcom_remove_sysmon_subdev() - release a qcom_sysmon
+ * @sysmon:	sysmon context, as retrieved by qcom_add_sysmon_subdev()
+ */
+void qcom_remove_sysmon_subdev(struct qcom_sysmon *sysmon)
+{
+	if (!sysmon)
+		return;
+
+	mutex_lock(&sysmon_lock);
+	list_del(&sysmon->node);
+	mutex_unlock(&sysmon_lock);
+
+	blocking_notifier_chain_unregister(&sysmon_notifiers, &sysmon->nb);
+
+	rproc_remove_subdev(sysmon->rproc, &sysmon->subdev);
+
+	qmi_handle_release(&sysmon->qmi);
+
+	kfree(sysmon);
+}
+EXPORT_SYMBOL_GPL(qcom_remove_sysmon_subdev);
+
+/**
+ * qcom_sysmon_shutdown_acked() - query the success of the last shutdown
+ * @sysmon:	sysmon context
+ *
+ * When sysmon is used to request a graceful shutdown of the remote processor
+ * this can be used by the remoteproc driver to query the success, in order to
+ * know if it should fall back to other means of requesting a shutdown.
+ *
+ * Return: boolean indicator of the success of the last shutdown request
+ */
+bool qcom_sysmon_shutdown_acked(struct qcom_sysmon *sysmon)
+{
+	return sysmon && sysmon->shutdown_acked;
+}
+EXPORT_SYMBOL_GPL(qcom_sysmon_shutdown_acked);
+
+/**
+ * sysmon_probe() - probe sys_mon channel
+ * @rpdev:	rpmsg device handle
+ *
+ * Find the sysmon context associated with the ancestor remoteproc and assign
+ * this rpmsg device with said sysmon context.
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+static int sysmon_probe(struct rpmsg_device *rpdev)
+{
+	struct qcom_sysmon *sysmon;
+	struct rproc *rproc;
+
+	rproc = rproc_get_by_child(&rpdev->dev);
+	if (!rproc) {
+		dev_err(&rpdev->dev, "sysmon device not child of rproc\n");
+		return -EINVAL;
+	}
+
+	mutex_lock(&sysmon_lock);
+	list_for_each_entry(sysmon, &sysmon_list, node) {
+		if (sysmon->rproc == rproc)
+			goto found;
+	}
+	mutex_unlock(&sysmon_lock);
+
+	dev_err(&rpdev->dev, "no sysmon associated with parent rproc\n");
+
+	return -EINVAL;
+
+found:
+	mutex_unlock(&sysmon_lock);
+
+	rpdev->ept->priv = sysmon;
+	sysmon->ept = rpdev->ept;
+
+	return 0;
+}
+
+/**
+ * sysmon_remove() - sys_mon channel remove handler
+ * @rpdev:	rpmsg device handle
+ *
+ * Disassociate the rpmsg device with the sysmon instance.
+ */
+static void sysmon_remove(struct rpmsg_device *rpdev)
+{
+	struct qcom_sysmon *sysmon = rpdev->ept->priv;
+
+	sysmon->ept = NULL;
+}
+
+static const struct rpmsg_device_id sysmon_match[] = {
+	{ "sys_mon" },
+	{}
+};
+
+static struct rpmsg_driver sysmon_driver = {
+	.probe = sysmon_probe,
+	.remove = sysmon_remove,
+	.callback = sysmon_callback,
+	.id_table = sysmon_match,
+	.drv = {
+		.name = "qcom_sysmon",
+	},
+};
+
+module_rpmsg_driver(sysmon_driver);
+
+MODULE_DESCRIPTION("Qualcomm sysmon driver");
+MODULE_LICENSE("GPL v2");