Add TIOCM Signals support for RPMSG char devices

index 8122807..3d7458a 100644
@@ -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 signal bits 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);

index 0d791c3..033656d 100644
@@ -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);

index 9fe156d..48c8ae3 100644
@@ -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 */

index e2ce4e6..e90f543 100644
@@ -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)

index a76b963..b136684 100644
@@ -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 <[email protected]>
  * 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 >= 0)
+			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 = {

index b136684..8a3cbe9 100644
@@ -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 >= 0)
 			ret = put_user(ret, (int __user *)arg);