[PATCH V2 2/3] rpmsg: glink: Add support to handle signals command

[Deepak Kumar Singh]

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 <quic_clew@xxxxxxxxxxx>
Signed-off-by: Deepak Kumar Singh <quic_deesin@xxxxxxxxxxx>
---
 drivers/rpmsg/qcom_glink_native.c | 77 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)

diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
index 3f377a7..d673d65 100644
--- a/drivers/rpmsg/qcom_glink_native.c
+++ b/drivers/rpmsg/qcom_glink_native.c
@@ -17,6 +17,7 @@
 #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>
 
@@ -205,9 +206,16 @@ static const struct rpmsg_endpoint_ops glink_endpoint_ops;
 #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)
+#define	SIG_MASK			0x0fff;
+
 static void qcom_glink_rx_done_work(struct work_struct *work);
 
 static struct glink_channel *qcom_glink_alloc_channel(struct qcom_glink *glink,
@@ -1003,6 +1011,70 @@ static int qcom_glink_rx_open_ack(struct qcom_glink *glink, unsigned int lcid)
 	return 0;
 }
 
+/**
+ * qcom_glink_set_flow_control() - convert a signal cmd to wire format and
+ * 				   transmit
+ * @ept:	Rpmsg endpoint for channel.
+ * @enable:	True/False - enable or disable flow control
+ *
+ * Return: 0 on success or standard Linux error code.
+ */
+static int qcom_glink_set_flow_control(struct rpmsg_endpoint *ept, bool enable)
+{
+	struct glink_channel *channel = to_glink_channel(ept);
+	struct qcom_glink *glink = channel->glink;
+	struct glink_msg msg;
+	u32 sigs;
+
+	/**
+	 * convert signals from TIOCM to NATIVE
+	 * sigs = TIOCM_DTR|TIOCM_RTS
+	 */
+	if (enable)
+		sigs |= NATIVE_DTR_SIG | NATIVE_CTS_SIG;
+	else
+		sigs |= ~(NATIVE_DTR_SIG | NATIVE_CTS_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 sigs)
+{
+	struct glink_channel *channel;
+	unsigned long flags;
+
+	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;
+	}
+
+	if (!channel->ept.sig_cb)
+		return 0;
+
+	/* convert signals from NATIVE to TIOCM */
+	if (sigs & NATIVE_DTR_SIG)
+		sigs |= TIOCM_DSR;
+	if (sigs & NATIVE_CTS_SIG)
+		sigs |= TIOCM_CTS;
+	if (sigs & NATIVE_CD_SIG)
+		sigs |= TIOCM_CD;
+	if (sigs & NATIVE_RI_SIG)
+		sigs |= TIOCM_RI;
+	sigs &= SIG_MASK;
+
+	channel->ept.sig_cb(channel->ept.rpdev, channel->ept.priv, sigs);
+
+	return 0;
+}
+
 static irqreturn_t qcom_glink_native_intr(int irq, void *data)
 {
 	struct qcom_glink *glink = data;
@@ -1067,6 +1139,10 @@ 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;
@@ -1442,6 +1518,7 @@ static const struct rpmsg_endpoint_ops glink_endpoint_ops = {
 	.sendto = qcom_glink_sendto,
 	.trysend = qcom_glink_trysend,
 	.trysendto = qcom_glink_trysendto,
+	.set_flow_control = qcom_glink_set_flow_control,
 };
 
 static void qcom_glink_rpdev_release(struct device *dev)
-- 
2.7.4