From: Prashanth K Date: Thu, 24 Apr 2025 12:11:42 +0000 (+0530) Subject: usb: gadget: u_serial: Implement remote wakeup capability X-Git-Tag: v6.16-rc1~28^2~67 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=3baea29dc0a7;p=linux-block.git 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: Prashanth K Link: https://lore.kernel.org/r/20250424121142.4180241-1-prashanth.k@oss.qualcomm.com Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/gadget/function/f_serial.c b/drivers/usb/gadget/function/f_serial.c index 8f7e7a2b2ff2..0f266bc067f5 100644 --- a/drivers/usb/gadget/function/f_serial.c +++ b/drivers/usb/gadget/function/f_serial.c @@ -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; } diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c index 36fff45e8c9b..41dee7c8cc7c 100644 --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -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;