Commit 3baea29d authored by Prashanth K's avatar Prashanth K Committed by Greg Kroah-Hartman
Browse files

usb: gadget: u_serial: Implement remote wakeup capability 



Implement the remote wakeup capability for u_serial. The newly added
function gserial_wakeup_host() wakes up the host when there is some
data to be sent while the device is suspended. Add gser_get_status()
callbacks to advertise f_serial interface as function wakeup capable.

Signed-off-by: default avatarPrashanth K <prashanth.k@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250424121142.4180241-1-prashanth.k@oss.qualcomm.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 11e80d37

drivers/usb/gadget/function/f_serial.c

+7 −0
Original line number Diff line number Diff line
@@ -364,6 +364,12 @@ static void gser_suspend(struct usb_function *f) 
	gserial_suspend(&gser->port);

}



static int gser_get_status(struct usb_function *f)

{

	return (f->func_wakeup_armed ? USB_INTRF_STAT_FUNC_RW : 0) |

		USB_INTRF_STAT_FUNC_RW_CAP;

}



static struct usb_function *gser_alloc(struct usb_function_instance *fi)

{

	struct f_gser	*gser;
@@ -387,6 +393,7 @@ static struct usb_function *gser_alloc(struct usb_function_instance *fi) 
	gser->port.func.free_func = gser_free;

	gser->port.func.resume = gser_resume;

	gser->port.func.suspend = gser_suspend;

	gser->port.func.get_status = gser_get_status;



	return &gser->port.func;

}

drivers/usb/gadget/function/u_serial.c

+43 −0
Original line number Diff line number Diff line
@@ -592,6 +592,17 @@ static int gs_start_io(struct gs_port *port) 
	return status;

}



static int gserial_wakeup_host(struct gserial *gser)

{

	struct usb_function	*func = &gser->func;

	struct usb_gadget	*gadget = func->config->cdev->gadget;



	if (func->func_suspended)

		return usb_func_wakeup(func);

	else

		return usb_gadget_wakeup(gadget);

}



/*-------------------------------------------------------------------------*/



/* TTY Driver */
@@ -746,6 +757,8 @@ static ssize_t gs_write(struct tty_struct *tty, const u8 *buf, size_t count) 
{

	struct gs_port	*port = tty->driver_data;

	unsigned long	flags;

	int ret = 0;

	struct gserial  *gser = port->port_usb;



	pr_vdebug("gs_write: ttyGS%d (%p) writing %zu bytes\n",

			port->port_num, tty, count);
@@ -753,6 +766,17 @@ static ssize_t gs_write(struct tty_struct *tty, const u8 *buf, size_t count) 
	spin_lock_irqsave(&port->port_lock, flags);

	if (count)

		count = kfifo_in(&port->port_write_buf, buf, count);



	if (port->suspended) {

		spin_unlock_irqrestore(&port->port_lock, flags);

		ret = gserial_wakeup_host(gser);

		if (ret) {

			pr_debug("ttyGS%d: Remote wakeup failed:%d\n", port->port_num, ret);

			return count;

		}

		spin_lock_irqsave(&port->port_lock, flags);

	}



	/* treat count == 0 as flush_chars() */

	if (port->port_usb)

		gs_start_tx(port);
@@ -781,10 +805,22 @@ static void gs_flush_chars(struct tty_struct *tty) 
{

	struct gs_port	*port = tty->driver_data;

	unsigned long	flags;

	int ret = 0;

	struct gserial  *gser = port->port_usb;



	pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);



	spin_lock_irqsave(&port->port_lock, flags);

	if (port->suspended) {

		spin_unlock_irqrestore(&port->port_lock, flags);

		ret = gserial_wakeup_host(gser);

		if (ret) {

			pr_debug("ttyGS%d: Remote wakeup failed:%d\n", port->port_num, ret);

			return;

		}

		spin_lock_irqsave(&port->port_lock, flags);

	}



	if (port->port_usb)

		gs_start_tx(port);

	spin_unlock_irqrestore(&port->port_lock, flags);
@@ -1464,6 +1500,13 @@ void gserial_suspend(struct gserial *gser) 
		return;

	}



	if (port->write_busy || port->write_started) {

		/* Wakeup to host if there are ongoing transfers */

		spin_unlock_irqrestore(&serial_port_lock, flags);

		if (!gserial_wakeup_host(gser))

			return;

	}



	spin_lock(&port->port_lock);

	spin_unlock(&serial_port_lock);

	port->suspended = true;