[PATCH V3 0/4] Add TIOCM Signals support for RPMSG char devices

[PATCH V3 0/4] Add TIOCM Signals support for RPMSG char devices

[Arun Kumar Neelakantam]

Glink transport support signals to exchange state notification between
local and remote side clients. Adding support to send/receive the signal
command and notify the clients through callback and POLL notification.

Changes since v1:
- Split the patches as per functional areas like core, char, glink
- Add set, clear mask for TIOCMSET
- Merge the char signal callback and POLLPRI patches

Changes since v2:
- Modify the rpmsg_get_signals function prototype

Arun Kumar Neelakantam (4):
  rpmsg: core: Add signal API support
  rpmsg: glink: Add support to handle signals command
  rpmsg: char: Add TIOCMGET/TIOCMSET ioctl support
  rpmsg: char: Add signal callback and POLLPRI support

 drivers/rpmsg/qcom_glink_native.c | 126 ++++++++++++++++++++++++++++++++++++++
 drivers/rpmsg/rpmsg_char.c        |  74 +++++++++++++++++++++-
 drivers/rpmsg/rpmsg_core.c        |  41 +++++++++++++
 drivers/rpmsg/rpmsg_internal.h    |   5 ++
 include/linux/rpmsg.h             |  26 ++++++++
 5 files changed, 269 insertions(+), 3 deletions(-)

-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH V3 1/4] rpmsg: core: Add signal API support

[Arun Kumar Neelakantam]

Some transports like Glink support the state notifications between
clients using signals similar to serial protocol signals.

Signed-off-by: Chris Lew <clew@codeaurora.org>
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
---
 drivers/rpmsg/rpmsg_core.c     | 41 +++++++++++++++++++++++++++++++++++++++++
 drivers/rpmsg/rpmsg_internal.h |  5 +++++
 include/linux/rpmsg.h          | 26 ++++++++++++++++++++++++++
 3 files changed, 72 insertions(+)

diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
index 8122807..e9b719b 100644
--- a/drivers/rpmsg/rpmsg_core.c
+++ b/drivers/rpmsg/rpmsg_core.c
@@ -2,6 +2,7 @@
 /*
  * remote processor messaging bus
  *
+ * Copyright (c) 2018, The Linux Foundation.
  * Copyright (C) 2011 Texas Instruments, Inc.
  * Copyright (C) 2011 Google, Inc.
  *
@@ -283,6 +284,42 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
 }
 EXPORT_SYMBOL(rpmsg_trysend_offchannel);
 
+/**
+ * rpmsg_get_signals() - get the signals for this endpoint
+ * @ept:	the rpmsg endpoint
+ *
+ * Returns 0 on success and an appropriate error value on failure.
+ */
+int rpmsg_get_signals(struct rpmsg_endpoint *ept)
+{
+	if (WARN_ON(!ept))
+		return -EINVAL;
+	if (!ept->ops->get_signals)
+		return -EOPNOTSUPP;
+
+	return ept->ops->get_signals(ept);
+}
+EXPORT_SYMBOL(rpmsg_get_signals);
+
+/**
+ * rpmsg_set_signals() - set the remote signals for this endpoint
+ * @ept:	the rpmsg endpoint
+ * @set:	set mask for signals
+ * @clear:	clear mask for signals
+ *
+ * Returns 0 on success and an appropriate error value on failure.
+ */
+int rpmsg_set_signals(struct rpmsg_endpoint *ept, u32 set, u32 clear)
+{
+	if (WARN_ON(!ept))
+		return -EINVAL;
+	if (!ept->ops->set_signals)
+		return -EOPNOTSUPP;
+
+	return ept->ops->set_signals(ept, set, clear);
+}
+EXPORT_SYMBOL(rpmsg_set_signals);
+
 /*
  * match an rpmsg channel with a channel info struct.
  * this is used to make sure we're not creating rpmsg devices for channels
@@ -468,6 +505,10 @@ static int rpmsg_dev_probe(struct device *dev)
 
 		rpdev->ept = ept;
 		rpdev->src = ept->addr;
+
+		if (rpdrv->signals)
+			ept->sig_cb = rpdrv->signals;
+
 	}
 
 	err = rpdrv->probe(rpdev);
diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
index 0d791c3..033656d 100644
--- a/drivers/rpmsg/rpmsg_internal.h
+++ b/drivers/rpmsg/rpmsg_internal.h
@@ -2,6 +2,7 @@
 /*
  * remote processor messaging bus internals
  *
+ * Copyright (c) 2018, The Linux Foundation.
  * Copyright (C) 2011 Texas Instruments, Inc.
  * Copyright (C) 2011 Google, Inc.
  *
@@ -46,6 +47,8 @@ struct rpmsg_device_ops {
  * @trysend:		see @rpmsg_trysend(), required
  * @trysendto:		see @rpmsg_trysendto(), optional
  * @trysend_offchannel:	see @rpmsg_trysend_offchannel(), optional
+ * @get_signals:	see @rpmsg_get_signals(), optional
+ * @set_signals:	see @rpmsg_set_signals(), optional
  *
  * Indirection table for the operations that a rpmsg backend should implement.
  * In addition to @destroy_ept, the backend must at least implement @send and
@@ -65,6 +68,8 @@ struct rpmsg_endpoint_ops {
 			     void *data, int len);
 	__poll_t (*poll)(struct rpmsg_endpoint *ept, struct file *filp,
 			     poll_table *wait);
+	int (*get_signals)(struct rpmsg_endpoint *ept);
+	int (*set_signals)(struct rpmsg_endpoint *ept, u32 set, u32 clear);
 };
 
 int rpmsg_register_device(struct rpmsg_device *rpdev);
diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
index 9fe156d..48c8ae3 100644
--- a/include/linux/rpmsg.h
+++ b/include/linux/rpmsg.h
@@ -2,6 +2,7 @@
 /*
  * Remote processor messaging
  *
+ * Copyright (c) 2018 The Linux Foundation.
  * Copyright (C) 2011 Texas Instruments, Inc.
  * Copyright (C) 2011 Google, Inc.
  * All rights reserved.
@@ -60,6 +61,7 @@ struct rpmsg_device {
 };
 
 typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32);
+typedef int (*rpmsg_rx_sig_t)(struct rpmsg_device *, void *, u32, u32);
 
 /**
  * struct rpmsg_endpoint - binds a local rpmsg address to its user
@@ -67,6 +69,7 @@ struct rpmsg_device {
  * @refcount: when this drops to zero, the ept is deallocated
  * @cb: rx callback handler
  * @cb_lock: must be taken before accessing/changing @cb
+ * @sig_cb: rx serial signal handler
  * @addr: local rpmsg address
  * @priv: private data for the driver's use
  *
@@ -89,6 +92,7 @@ struct rpmsg_endpoint {
 	struct kref refcount;
 	rpmsg_rx_cb_t cb;
 	struct mutex cb_lock;
+	rpmsg_rx_sig_t sig_cb;
 	u32 addr;
 	void *priv;
 
@@ -102,6 +106,7 @@ struct rpmsg_endpoint {
  * @probe: invoked when a matching rpmsg channel (i.e. device) is found
  * @remove: invoked when the rpmsg channel is removed
  * @callback: invoked when an inbound message is received on the channel
+ * @signals: invoked when a serial signal change is received on the channel
  */
 struct rpmsg_driver {
 	struct device_driver drv;
@@ -109,6 +114,7 @@ struct rpmsg_driver {
 	int (*probe)(struct rpmsg_device *dev);
 	void (*remove)(struct rpmsg_device *dev);
 	int (*callback)(struct rpmsg_device *, void *, int, void *, u32);
+	int (*signals)(struct rpmsg_device *, void *, u32, u32);
 };
 
 #if IS_ENABLED(CONFIG_RPMSG)
@@ -135,6 +141,9 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
 __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
 			poll_table *wait);
 
+int rpmsg_get_signals(struct rpmsg_endpoint *ept);
+int rpmsg_set_signals(struct rpmsg_endpoint *ept, u32 set, u32 clear);
+
 #else
 
 static inline int register_rpmsg_device(struct rpmsg_device *dev)
@@ -242,6 +251,23 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept,
 	return 0;
 }
 
+static inline int rpmsg_get_signals(struct rpmsg_endpoint *ept)
+{
+	/* This shouldn't be possible */
+	WARN_ON(1);
+
+	return -ENXIO;
+}
+
+static inline int rpmsg_set_signals(struct rpmsg_endpoint *ept,
+				    u32 set, u32 clear)
+{
+	/* This shouldn't be possible */
+	WARN_ON(1);
+
+	return -ENXIO;
+}
+
 #endif /* IS_ENABLED(CONFIG_RPMSG) */
 
 /* use a macro to avoid include chaining to get THIS_MODULE */
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH V3 1/4] rpmsg: core: Add signal API support

[Bjorn Andersson]

On Thu 04 Oct 23:59 PDT 2018, Arun Kumar Neelakantam wrote:
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
[..]
> +/**
> + * rpmsg_get_signals() - get the signals for this endpoint
> + * @ept:	the rpmsg endpoint
> + *
> + * Returns 0 on success and an appropriate error value on failure.

I like the fact that you're using the return value to pass the bits, but
the comment doesn't reflect this - and you don't handle this properly in
the TIOCMGET case in patch 3.

> + */
> +int rpmsg_get_signals(struct rpmsg_endpoint *ept)
> +{
> +	if (WARN_ON(!ept))
> +		return -EINVAL;
> +	if (!ept->ops->get_signals)
> +		return -EOPNOTSUPP;
> +
> +	return ept->ops->get_signals(ept);
> +}
> +EXPORT_SYMBOL(rpmsg_get_signals);

Apart from that the series looks good.

Regards,
Bjorn

[PATCH V3 2/4] rpmsg: glink: Add support to handle signals command

[Arun Kumar Neelakantam]

Remote peripherals send signal notifications over glink with commandID 15.

Add support to send and receive the signal command and convert the signals
from NATIVE to TIOCM while receiving and vice versa while sending.

Signed-off-by: Chris Lew <clew@codeaurora.org>
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
---
 drivers/rpmsg/qcom_glink_native.c | 126 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 126 insertions(+)

diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
index e2ce4e6..e90f543 100644
--- a/drivers/rpmsg/qcom_glink_native.c
+++ b/drivers/rpmsg/qcom_glink_native.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
+ * Copyright (c) 2018, The Linux Foundation.
  * Copyright (c) 2016-2017, Linaro Ltd
  */
 
@@ -17,6 +18,7 @@
 #include <linux/rpmsg.h>
 #include <linux/sizes.h>
 #include <linux/slab.h>
+#include <linux/termios.h>
 #include <linux/workqueue.h>
 #include <linux/mailbox_client.h>
 
@@ -150,6 +152,8 @@ enum {
  * @intent_req_lock: Synchronises multiple intent requests
  * @intent_req_result: Result of intent request
  * @intent_req_comp: Completion for intent_req signalling
+ * @lsigs:	local side signals
+ * @rsigs:	remote side signals
  */
 struct glink_channel {
 	struct rpmsg_endpoint ept;
@@ -181,6 +185,10 @@ struct glink_channel {
 	struct mutex intent_req_lock;
 	bool intent_req_result;
 	struct completion intent_req_comp;
+
+	unsigned int lsigs;
+	unsigned int rsigs;
+
 };
 
 #define to_glink_channel(_ept) container_of(_ept, struct glink_channel, ept)
@@ -201,9 +209,15 @@ struct glink_channel {
 #define RPM_CMD_TX_DATA_CONT		12
 #define RPM_CMD_READ_NOTIF		13
 #define RPM_CMD_RX_DONE_W_REUSE		14
+#define RPM_CMD_SIGNALS			15
 
 #define GLINK_FEATURE_INTENTLESS	BIT(1)
 
+#define NATIVE_DTR_SIG	BIT(31)
+#define NATIVE_CTS_SIG	BIT(30)
+#define NATIVE_CD_SIG	BIT(29)
+#define NATIVE_RI_SIG	BIT(28)
+
 static void qcom_glink_rx_done_work(struct work_struct *work);
 
 static struct glink_channel *qcom_glink_alloc_channel(struct qcom_glink *glink,
@@ -957,6 +971,76 @@ static int qcom_glink_rx_open_ack(struct qcom_glink *glink, unsigned int lcid)
 	return 0;
 }
 
+/**
+ * qcom_glink_send_signals() - convert a signal  cmd to wire format and transmit
+ * @glink:	The transport to transmit on.
+ * @channel:	The glink channel
+ * @sigs:	The signals to encode.
+ *
+ * Return: 0 on success or standard Linux error code.
+ */
+static int qcom_glink_send_signals(struct qcom_glink *glink,
+				   struct glink_channel *channel,
+				   u32 sigs)
+{
+	struct glink_msg msg;
+
+	/* convert signals from TIOCM to NATIVE */
+	sigs &= 0x0fff;
+	if (sigs & TIOCM_DTR)
+		sigs |= NATIVE_DTR_SIG;
+	if (sigs & TIOCM_RTS)
+		sigs |= NATIVE_CTS_SIG;
+	if (sigs & TIOCM_CD)
+		sigs |= NATIVE_CD_SIG;
+	if (sigs & TIOCM_RI)
+		sigs |= NATIVE_RI_SIG;
+
+	msg.cmd = cpu_to_le16(RPM_CMD_SIGNALS);
+	msg.param1 = cpu_to_le16(channel->lcid);
+	msg.param2 = cpu_to_le32(sigs);
+
+	return qcom_glink_tx(glink, &msg, sizeof(msg), NULL, 0, true);
+}
+
+static int qcom_glink_handle_signals(struct qcom_glink *glink,
+				     unsigned int rcid, unsigned int signals)
+{
+	struct glink_channel *channel;
+	unsigned long flags;
+	u32 old;
+
+	spin_lock_irqsave(&glink->idr_lock, flags);
+	channel = idr_find(&glink->rcids, rcid);
+	spin_unlock_irqrestore(&glink->idr_lock, flags);
+	if (!channel) {
+		dev_err(glink->dev, "signal for non-existing channel\n");
+		return -EINVAL;
+	}
+
+	old = channel->rsigs;
+
+	/* convert signals from NATIVE to TIOCM */
+	if (signals & NATIVE_DTR_SIG)
+		signals |= TIOCM_DSR;
+	if (signals & NATIVE_CTS_SIG)
+		signals |= TIOCM_CTS;
+	if (signals & NATIVE_CD_SIG)
+		signals |= TIOCM_CD;
+	if (signals & NATIVE_RI_SIG)
+		signals |= TIOCM_RI;
+	signals &= 0x0fff;
+
+	channel->rsigs = signals;
+
+	if (channel->ept.sig_cb) {
+		channel->ept.sig_cb(channel->ept.rpdev, channel->ept.priv,
+				    old, channel->rsigs);
+	}
+
+	return 0;
+}
+
 static irqreturn_t qcom_glink_native_intr(int irq, void *data)
 {
 	struct qcom_glink *glink = data;
@@ -1018,6 +1102,10 @@ static irqreturn_t qcom_glink_native_intr(int irq, void *data)
 			qcom_glink_handle_intent_req_ack(glink, param1, param2);
 			qcom_glink_rx_advance(glink, ALIGN(sizeof(msg), 8));
 			break;
+		case RPM_CMD_SIGNALS:
+			qcom_glink_handle_signals(glink, param1, param2);
+			qcom_glink_rx_advance(glink, ALIGN(sizeof(msg), 8));
+			break;
 		default:
 			dev_err(glink->dev, "unhandled rx cmd: %d\n", cmd);
 			ret = -EINVAL;
@@ -1315,6 +1403,42 @@ static int qcom_glink_trysend(struct rpmsg_endpoint *ept, void *data, int len)
 	return __qcom_glink_send(channel, data, len, false);
 }
 
+static int qcom_glink_get_sigs(struct rpmsg_endpoint *ept)
+{
+	struct glink_channel *channel = to_glink_channel(ept);
+
+	return channel->rsigs;
+}
+
+static int qcom_glink_set_sigs(struct rpmsg_endpoint *ept, u32 set, u32 clear)
+{
+	struct glink_channel *channel = to_glink_channel(ept);
+	struct qcom_glink *glink = channel->glink;
+	u32 sigs = channel->lsigs;
+
+	if (set & TIOCM_DTR)
+		sigs |= TIOCM_DTR;
+	if (set & TIOCM_RTS)
+		sigs |= TIOCM_RTS;
+	if (set & TIOCM_CD)
+		sigs |= TIOCM_CD;
+	if (set & TIOCM_RI)
+		sigs |= TIOCM_RI;
+
+	if (clear & TIOCM_DTR)
+		sigs &= ~TIOCM_DTR;
+	if (clear & TIOCM_RTS)
+		sigs &= ~TIOCM_RTS;
+	if (clear & TIOCM_CD)
+		sigs &= ~TIOCM_CD;
+	if (clear & TIOCM_RI)
+		sigs &= ~TIOCM_RI;
+
+	channel->lsigs = sigs;
+
+	return qcom_glink_send_signals(glink, channel, sigs);
+}
+
 /*
  * Finds the device_node for the glink child interested in this channel.
  */
@@ -1348,6 +1472,8 @@ static struct device_node *qcom_glink_match_channel(struct device_node *node,
 	.destroy_ept = qcom_glink_destroy_ept,
 	.send = qcom_glink_send,
 	.trysend = qcom_glink_trysend,
+	.get_signals = qcom_glink_get_sigs,
+	.set_signals = qcom_glink_set_sigs,
 };
 
 static void qcom_glink_rpdev_release(struct device *dev)
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH V3 3/4] rpmsg: char: Add TIOCMGET/TIOCMSET ioctl support

[Arun Kumar Neelakantam]

Add TICOMGET and TIOCMSET ioctl support for rpmsg char device nodes
to get/set the low level transport signals.

Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
---
 drivers/rpmsg/rpmsg_char.c | 53 +++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 50 insertions(+), 3 deletions(-)

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index a76b963..16978f7b 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
+ * Copyright (c) 2018, The Linux Foundation.
  * Copyright (c) 2016, Linaro Ltd.
  * Copyright (c) 2012, Michal Simek <monstr@monstr.eu>
  * Copyright (c) 2012, PetaLogix
@@ -19,6 +20,7 @@
 #include <linux/rpmsg.h>
 #include <linux/skbuff.h>
 #include <linux/slab.h>
+#include <linux/termios.h>
 #include <linux/uaccess.h>
 #include <uapi/linux/rpmsg.h>
 
@@ -266,15 +268,60 @@ static __poll_t rpmsg_eptdev_poll(struct file *filp, poll_table *wait)
 	return mask;
 }
 
+static int rpmsg_eptdev_tiocmset(struct file *fp, unsigned int cmd,
+				 int __user *arg)
+{
+	struct rpmsg_eptdev *eptdev = fp->private_data;
+	u32 set, clear, val;
+	int ret;
+
+	ret = get_user(val, arg);
+	if (ret)
+		return ret;
+	set = clear = 0;
+	switch (cmd) {
+	case TIOCMBIS:
+		set = val;
+		break;
+	case TIOCMBIC:
+		clear = val;
+		break;
+	case TIOCMSET:
+		set = val;
+		clear = ~val;
+		break;
+	}
+
+	set &= TIOCM_DTR | TIOCM_RTS | TIOCM_CD | TIOCM_RI;
+	clear &= TIOCM_DTR | TIOCM_RTS | TIOCM_CD | TIOCM_RI;
+
+	return rpmsg_set_signals(eptdev->ept, set, clear);
+}
+
 static long rpmsg_eptdev_ioctl(struct file *fp, unsigned int cmd,
 			       unsigned long arg)
 {
 	struct rpmsg_eptdev *eptdev = fp->private_data;
+	int ret;
 
-	if (cmd != RPMSG_DESTROY_EPT_IOCTL)
-		return -EINVAL;
+	switch (cmd) {
+	case TIOCMGET:
+		ret = rpmsg_get_signals(eptdev->ept);
+		if (!ret)
+			ret = put_user(ret, (int __user *)arg);
+		break;
+	case TIOCMSET:
+	case TIOCMBIS:
+	case TIOCMBIC:
+		ret = rpmsg_eptdev_tiocmset(fp, cmd, (int __user *)arg);
+		break;
+	case RPMSG_DESTROY_EPT_IOCTL:
+		ret = rpmsg_eptdev_destroy(&eptdev->dev, NULL);
+	default:
+		ret = -EINVAL;
+	}
 
-	return rpmsg_eptdev_destroy(&eptdev->dev, NULL);
+	return ret;
 }
 
 static const struct file_operations rpmsg_eptdev_fops = {
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH V3 4/4] rpmsg: char: Add signal callback and POLLPRI support

[Arun Kumar Neelakantam]

Register a callback to get the signal notifications from rpmsg and
send POLLPRI mask to indicate the signal change in POLL system call.

Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
---
 drivers/rpmsg/rpmsg_char.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index 16978f7b..a5855f7 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -64,6 +64,7 @@ struct rpmsg_ctrldev {
  * @queue_lock:	synchronization of @queue operations
  * @queue:	incoming message queue
  * @readq:	wait object for incoming queue
+ * @sig_pending:state of signal notification
  */
 struct rpmsg_eptdev {
 	struct device dev;
@@ -78,6 +79,8 @@ struct rpmsg_eptdev {
 	spinlock_t queue_lock;
 	struct sk_buff_head queue;
 	wait_queue_head_t readq;
+
+	bool sig_pending;
 };
 
 static int rpmsg_eptdev_destroy(struct device *dev, void *data)
@@ -122,6 +125,18 @@ static int rpmsg_ept_cb(struct rpmsg_device *rpdev, void *buf, int len,
 	return 0;
 }
 
+static int rpmsg_sigs_cb(struct rpmsg_device *rpdev, void *priv,
+			 u32 old, u32 new)
+{
+	struct rpmsg_eptdev *eptdev = priv;
+
+	eptdev->sig_pending = true;
+
+	/* wake up any blocking processes, waiting for signal notification */
+	wake_up_interruptible(&eptdev->readq);
+	return 0;
+}
+
 static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
 {
 	struct rpmsg_eptdev *eptdev = cdev_to_eptdev(inode->i_cdev);
@@ -138,6 +153,7 @@ static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
 		return -EINVAL;
 	}
 
+	ept->sig_cb = rpmsg_sigs_cb;
 	eptdev->ept = ept;
 	filp->private_data = eptdev;
 
@@ -157,6 +173,7 @@ static int rpmsg_eptdev_release(struct inode *inode, struct file *filp)
 		eptdev->ept = NULL;
 	}
 	mutex_unlock(&eptdev->ept_lock);
+	eptdev->sig_pending = false;
 
 	/* Discard all SKBs */
 	while (!skb_queue_empty(&eptdev->queue)) {
@@ -263,6 +280,9 @@ static __poll_t rpmsg_eptdev_poll(struct file *filp, poll_table *wait)
 	if (!skb_queue_empty(&eptdev->queue))
 		mask |= EPOLLIN | EPOLLRDNORM;
 
+	if (eptdev->sig_pending)
+		mask |= POLLPRI;
+
 	mask |= rpmsg_poll(eptdev->ept, filp, wait);
 
 	return mask;
@@ -306,6 +326,7 @@ static long rpmsg_eptdev_ioctl(struct file *fp, unsigned int cmd,
 
 	switch (cmd) {
 	case TIOCMGET:
+		eptdev->sig_pending = false;
 		ret = rpmsg_get_signals(eptdev->ept);
 		if (!ret)
 			ret = put_user(ret, (int __user *)arg);
-- 
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