linux-kernel - [PATCH 2/8] usb: gadget: u_serial: propagate poll() to the next layer

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Date:   Mon, 12 Jun 2017 20:26:09 +0300
From:   Tal Shorer <tal.shorer@...il.com>
To:     linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, gregkh@...uxfoundation.org,
        balbi@...nel.org, corbet@....net
Cc:     Tal Shorer <tal.shorer@...il.com>
Subject: [PATCH 2/8] usb: gadget: u_serial: propagate poll() to the next layer

In order for a serial function to add flags to the poll() mask of their
tty files, propagate the poll() callback to the next layer so it can
return a mask if it sees fit to do so.

Signed-off-by: Tal Shorer <tal.shorer@...il.com>
---
 drivers/usb/gadget/function/u_serial.c | 16 ++++++++++++++++
 drivers/usb/gadget/function/u_serial.h |  3 +++
 2 files changed, 19 insertions(+)

diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 9b0805f..d466f58 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -1025,6 +1025,21 @@ static int gs_break_ctl(struct tty_struct *tty, int duration)
 	return status;
 }
 
+static unsigned int gs_poll(struct tty_struct *tty, struct file *file,
+	poll_table *wait)
+{
+	struct gs_port *port = tty->driver_data;
+	struct gserial *gser;
+	unsigned int mask = 0;
+
+	spin_lock_irq(&port->port_lock);
+	gser = port->port_usb;
+	if (gser && gser->poll)
+		mask |= gser->poll(gser, file, wait);
+	spin_unlock_irq(&port->port_lock);
+	return mask;
+}
+
 static const struct tty_operations gs_tty_ops = {
 	.open =			gs_open,
 	.close =		gs_close,
@@ -1035,6 +1050,7 @@ static const struct tty_operations gs_tty_ops = {
 	.chars_in_buffer =	gs_chars_in_buffer,
 	.unthrottle =		gs_unthrottle,
 	.break_ctl =		gs_break_ctl,
+	.poll =			gs_poll,
 };
 
 /*-------------------------------------------------------------------------*/
diff --git a/drivers/usb/gadget/function/u_serial.h b/drivers/usb/gadget/function/u_serial.h
index c20210c..ce00840 100644
--- a/drivers/usb/gadget/function/u_serial.h
+++ b/drivers/usb/gadget/function/u_serial.h
@@ -12,6 +12,7 @@
 #ifndef __U_SERIAL_H
 #define __U_SERIAL_H
 
+#include <linux/poll.h>
 #include <linux/usb/composite.h>
 #include <linux/usb/cdc.h>
 
@@ -50,6 +51,8 @@ struct gserial {
 	void (*connect)(struct gserial *p);
 	void (*disconnect)(struct gserial *p);
 	int (*send_break)(struct gserial *p, int duration);
+	unsigned int (*poll)(struct gserial *p, struct file *file,
+				poll_table *wait);
 };
 
 /* utilities to allocate/free request and buffer */
-- 
2.7.4