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usb: gadget: u_serial: add suspend resume callbacks
Add suspend resume callbacks to handle the case seen when the bus is suspended by the HOST, and the device opens the port (cat /dev/ttyGS0). Gadget controller (like DWC2) doesn't accept usb requests to be queued in this case (when in L2 state), from the gs_open() call. Error log is printed - configfs-gadget gadget: acm ttyGS0 can't notify serial state, -11 If the HOST resumes (opens) the bus, the port still isn't functional. Use suspend/resume callbacks to monitor the gadget suspended state by using 'suspended' flag. In case the port gets opened (cat /dev/ttyGS0), the I/O stream will be delayed until the bus gets resumed by the HOST. Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> Signed-off-by: Felipe Balbi <balbi@kernel.org>
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@ -120,6 +120,8 @@ struct gs_port {
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wait_queue_head_t drain_wait; /* wait while writes drain */
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bool write_busy;
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wait_queue_head_t close_wait;
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bool suspended; /* port suspended */
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bool start_delayed; /* delay start when suspended */
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/* REVISIT this state ... */
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struct usb_cdc_line_coding port_line_coding; /* 8-N-1 etc */
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@ -630,13 +632,19 @@ static int gs_open(struct tty_struct *tty, struct file *file)
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/* if connected, start the I/O stream */
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if (port->port_usb) {
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struct gserial *gser = port->port_usb;
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/* if port is suspended, wait resume to start I/0 stream */
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if (!port->suspended) {
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struct gserial *gser = port->port_usb;
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pr_debug("gs_open: start ttyGS%d\n", port->port_num);
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gs_start_io(port);
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pr_debug("gs_open: start ttyGS%d\n", port->port_num);
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gs_start_io(port);
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if (gser->connect)
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gser->connect(gser);
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if (gser->connect)
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gser->connect(gser);
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} else {
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pr_debug("delay start of ttyGS%d\n", port->port_num);
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port->start_delayed = true;
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}
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}
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pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
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@ -680,7 +688,7 @@ raced_with_open:
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pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
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gser = port->port_usb;
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if (gser && gser->disconnect)
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if (gser && !port->suspended && gser->disconnect)
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gser->disconnect(gser);
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/* wait for circular write buffer to drain, disconnect, or at
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@ -708,6 +716,7 @@ raced_with_open:
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else
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kfifo_reset(&port->port_write_buf);
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port->start_delayed = false;
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port->port.count = 0;
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port->port.tty = NULL;
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@ -1403,6 +1412,38 @@ void gserial_disconnect(struct gserial *gser)
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}
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EXPORT_SYMBOL_GPL(gserial_disconnect);
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void gserial_suspend(struct gserial *gser)
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{
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struct gs_port *port = gser->ioport;
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unsigned long flags;
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spin_lock_irqsave(&port->port_lock, flags);
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port->suspended = true;
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spin_unlock_irqrestore(&port->port_lock, flags);
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}
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EXPORT_SYMBOL_GPL(gserial_suspend);
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void gserial_resume(struct gserial *gser)
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{
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struct gs_port *port = gser->ioport;
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unsigned long flags;
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spin_lock_irqsave(&port->port_lock, flags);
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port->suspended = false;
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if (!port->start_delayed) {
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spin_unlock_irqrestore(&port->port_lock, flags);
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return;
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}
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pr_debug("delayed start ttyGS%d\n", port->port_num);
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gs_start_io(port);
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if (gser->connect)
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gser->connect(gser);
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port->start_delayed = false;
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spin_unlock_irqrestore(&port->port_lock, flags);
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}
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EXPORT_SYMBOL_GPL(gserial_resume);
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static int userial_init(void)
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{
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unsigned i;
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@ -68,6 +68,8 @@ ssize_t gserial_get_console(unsigned char port_num, char *page);
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/* connect/disconnect is handled by individual functions */
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int gserial_connect(struct gserial *, u8 port_num);
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void gserial_disconnect(struct gserial *);
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void gserial_suspend(struct gserial *p);
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void gserial_resume(struct gserial *p);
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/* functions are bound to configurations by a config or gadget driver */
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int gser_bind_config(struct usb_configuration *c, u8 port_num);
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