607 lines
15 KiB
C
607 lines
15 KiB
C
/*
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* u_serial.c - utilities for USB gadget "serial port"/TTY support
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*
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* Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
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* Copyright (C) 2008 David Brownell
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* Copyright (C) 2008 by Nokia Corporation
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*
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* This code also borrows from usbserial.c, which is
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* Copyright (C) 1999 - 2002 Greg Kroah-Hartman (greg@kroah.com)
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* Copyright (C) 2000 Peter Berger (pberger@brimson.com)
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* Copyright (C) 2000 Al Borchers (alborchers@steinerpoint.com)
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*
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* This software is distributed under the terms of the GNU General
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* Public License ("GPL") as published by the Free Software Foundation,
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* either version 2 of that License or (at your option) any later version.
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*/
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/* #define VERBOSE_DEBUG */
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#include <common.h>
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#include <complete.h>
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#include <usb/cdc.h>
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#include <kfifo.h>
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#include <clock.h>
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#include <linux/err.h>
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#include <dma.h>
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#include "u_serial.h"
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/*
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* This component encapsulates the TTY layer glue needed to provide basic
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* "serial port" functionality through the USB gadget stack. Each such
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* port is exposed through a /dev/ttyGS* node.
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*
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* After this module has been loaded, the individual TTY port can be requested
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* (gserial_alloc_line()) and it will stay available until they are removed
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* (gserial_free_line()). Each one may be connected to a USB function
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* (gserial_connect), or disconnected (with gserial_disconnect) when the USB
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* host issues a config change event. Data can only flow when the port is
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* connected to the host.
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*
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* A given TTY port can be made available in multiple configurations.
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* For example, each one might expose a ttyGS0 node which provides a
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* login application. In one case that might use CDC ACM interface 0,
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* while another configuration might use interface 3 for that. The
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* work to handle that (including descriptor management) is not part
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* of this component.
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*
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* Configurations may expose more than one TTY port. For example, if
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* ttyGS0 provides login service, then ttyGS1 might provide dialer access
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* for a telephone or fax link. And ttyGS2 might be something that just
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* needs a simple byte stream interface for some messaging protocol that
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* is managed in userspace ... OBEX, PTP, and MTP have been mentioned.
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*/
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#define PREFIX "ttyGS"
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/*
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* gserial is the lifecycle interface, used by USB functions
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* gs_port is the I/O nexus, used by the tty driver
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* tty_struct links to the tty/filesystem framework
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*
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* gserial <---> gs_port ... links will be null when the USB link is
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* inactive; managed by gserial_{connect,disconnect}(). each gserial
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* instance can wrap its own USB control protocol.
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* gserial->ioport == usb_ep->driver_data ... gs_port
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* gs_port->port_usb ... gserial
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*
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* gs_port <---> tty_struct ... links will be null when the TTY file
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* isn't opened; managed by gs_open()/gs_close()
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* gserial->port_tty ... tty_struct
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* tty_struct->driver_data ... gserial
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*/
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/* RX and TX queues can buffer QUEUE_SIZE packets before they hit the
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* next layer of buffering. For TX that's a circular buffer; for RX
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* consider it a NOP. A third layer is provided by the TTY code.
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*/
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#define QUEUE_SIZE 16
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#define WRITE_BUF_SIZE 8192 /* TX only */
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#define RECV_FIFO_SIZE (1024 * 8)
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/* circular buffer */
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struct gs_buf {
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unsigned buf_size;
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char *buf_buf;
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char *buf_get;
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char *buf_put;
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};
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/*
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* The port structure holds info for each port, one for each minor number
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* (and thus for each /dev/ node).
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*/
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struct gs_port {
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struct gserial *port_usb;
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struct console_device cdev;
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struct kfifo *recv_fifo;
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u8 port_num;
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struct list_head read_pool;
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unsigned read_nb_queued;
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struct list_head write_pool;
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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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};
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static struct portmaster {
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struct gs_port *port;
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} ports[MAX_U_SERIAL_PORTS];
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#define GS_CLOSE_TIMEOUT 15 /* seconds */
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static unsigned gs_start_rx(struct gs_port *port)
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{
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struct list_head *pool = &port->read_pool;
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struct usb_ep *out = port->port_usb->out;
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unsigned started = 0;
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while (!list_empty(pool) &&
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((out->maxpacket * (port->read_nb_queued + 1) +
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kfifo_len(port->recv_fifo)) < RECV_FIFO_SIZE)) {
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struct usb_request *req;
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int status;
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req = list_entry(pool->next, struct usb_request, list);
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list_del(&req->list);
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req->length = out->maxpacket;
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/* drop lock while we call out; the controller driver
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* may need to call us back (e.g. for disconnect)
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*/
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port->read_nb_queued++;
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status = usb_ep_queue(out, req);
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if (status) {
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pr_debug("%s: %s %s err %d\n",
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__func__, "queue", out->name, status);
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list_add(&req->list, pool);
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break;
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}
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started++;
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/* abort immediately after disconnect */
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if (!port->port_usb)
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break;
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}
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return started;
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}
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/*-------------------------------------------------------------------------*/
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static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
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{
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struct gs_port *port = ep->driver_data;
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if (req->status == -ESHUTDOWN)
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return;
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kfifo_put(port->recv_fifo, req->buf, req->actual);
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list_add_tail(&req->list, &port->read_pool);
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port->read_nb_queued--;
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gs_start_rx(port);
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}
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/*-------------------------------------------------------------------------*/
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/* I/O glue between TTY (upper) and USB function (lower) driver layers */
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static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
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{
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struct gs_port *port = ep->driver_data;
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list_add(&req->list, &port->write_pool);
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switch (req->status) {
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default:
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/* presumably a transient fault */
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pr_warning("%s: unexpected %s status %d\n",
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__func__, ep->name, req->status);
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/* FALL THROUGH */
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case 0:
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/* normal completion */
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break;
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case -ESHUTDOWN:
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/* disconnect */
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pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
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break;
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}
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}
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/*
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* gs_alloc_req
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*
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* Allocate a usb_request and its buffer. Returns a pointer to the
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* usb_request or NULL if there is an error.
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*/
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struct usb_request *
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gs_alloc_req(struct usb_ep *ep, unsigned len)
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{
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struct usb_request *req;
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req = usb_ep_alloc_request(ep);
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if (req != NULL) {
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req->length = len;
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req->buf = dma_alloc(len);
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}
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return req;
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}
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EXPORT_SYMBOL_GPL(gs_alloc_req);
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/*
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* gs_free_req
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*
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* Free a usb_request and its buffer.
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*/
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void gs_free_req(struct usb_ep *ep, struct usb_request *req)
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{
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kfree(req->buf);
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usb_ep_free_request(ep, req);
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}
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EXPORT_SYMBOL_GPL(gs_free_req);
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static void gs_free_requests(struct usb_ep *ep, struct list_head *head)
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{
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struct usb_request *req;
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while (!list_empty(head)) {
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req = list_entry(head->next, struct usb_request, list);
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list_del(&req->list);
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gs_free_req(ep, req);
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}
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}
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static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
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void (*fn)(struct usb_ep *, struct usb_request *))
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{
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int i;
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struct usb_request *req;
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/* Pre-allocate up to QUEUE_SIZE transfers, but if we can't
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* do quite that many this time, don't fail ... we just won't
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* be as speedy as we might otherwise be.
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*/
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for (i = 0; i < QUEUE_SIZE; i++) {
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req = gs_alloc_req(ep, ep->maxpacket);
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if (!req)
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return list_empty(head) ? -ENOMEM : 0;
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req->complete = fn;
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list_add_tail(&req->list, head);
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}
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return 0;
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}
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/**
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* gs_start_io - start USB I/O streams
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* @dev: encapsulates endpoints to use
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* Context: holding port_lock; port_tty and port_usb are non-null
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*
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* We only start I/O when something is connected to both sides of
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* this port. If nothing is listening on the host side, we may
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* be pointlessly filling up our TX buffers and FIFO.
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*/
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static int gs_start_io(struct gs_port *port)
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{
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struct list_head *head = &port->read_pool;
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struct usb_ep *ep = port->port_usb->out;
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int status;
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unsigned started;
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/* Allocate RX and TX I/O buffers. We can't easily do this much
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* earlier (with GFP_KERNEL) because the requests are coupled to
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* endpoints, as are the packet sizes we'll be using. Different
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* configurations may use different endpoints with a given port;
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* and high speed vs full speed changes packet sizes too.
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*/
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status = gs_alloc_requests(ep, head, gs_read_complete);
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if (status)
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return status;
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status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
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gs_write_complete);
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if (status) {
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gs_free_requests(ep, head);
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return status;
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}
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/* queue read requests */
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port->read_nb_queued = 0;
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started = gs_start_rx(port);
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/* unblock any pending writes into our circular buffer */
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if (!started) {
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gs_free_requests(ep, head);
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gs_free_requests(port->port_usb->in, &port->write_pool);
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status = -EIO;
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}
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return status;
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}
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/*-------------------------------------------------------------------------*/
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static int
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gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
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{
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struct gs_port *port;
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int ret = 0;
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if (ports[port_num].port) {
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ret = -EBUSY;
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goto out;
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}
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port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);
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if (port == NULL) {
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ret = -ENOMEM;
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goto out;
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}
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INIT_LIST_HEAD(&port->read_pool);
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INIT_LIST_HEAD(&port->write_pool);
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port->port_num = port_num;
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port->port_line_coding = *coding;
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ports[port_num].port = port;
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out:
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return ret;
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}
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static void gserial_free_port(struct gs_port *port)
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{
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kfree(port);
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}
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void gserial_free_line(unsigned char port_num)
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{
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struct gs_port *port;
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if (WARN_ON(!ports[port_num].port))
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return;
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port = ports[port_num].port;
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ports[port_num].port = NULL;
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gserial_free_port(port);
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}
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EXPORT_SYMBOL_GPL(gserial_free_line);
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int gserial_alloc_line(unsigned char *line_num)
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{
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struct usb_cdc_line_coding coding;
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int ret;
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int port_num;
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coding.dwDTERate = cpu_to_le32(9600);
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coding.bCharFormat = 8;
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coding.bParityType = USB_CDC_NO_PARITY;
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coding.bDataBits = USB_CDC_1_STOP_BITS;
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for (port_num = 0; port_num < MAX_U_SERIAL_PORTS; port_num++) {
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ret = gs_port_alloc(port_num, &coding);
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if (ret == -EBUSY)
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continue;
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if (ret)
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return ret;
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break;
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}
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if (ret)
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return ret;
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/* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
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*line_num = port_num;
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return ret;
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}
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EXPORT_SYMBOL_GPL(gserial_alloc_line);
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static void serial_putc(struct console_device *cdev, char c)
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{
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struct gs_port *port = container_of(cdev,
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struct gs_port, cdev);
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struct list_head *pool = &port->write_pool;
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struct usb_ep *in;
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struct usb_request *req;
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int status;
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uint64_t to;
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if (list_empty(pool))
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return;
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in = port->port_usb->in;
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req = list_entry(pool->next, struct usb_request, list);
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req->length = 1;
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list_del(&req->list);
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*(unsigned char *)req->buf = c;
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status = usb_ep_queue(in, req);
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to = get_time_ns();
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while (status >= 0 && list_empty(pool)) {
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status = usb_gadget_poll();
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if (is_timeout(to, 300 * MSECOND))
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break;
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}
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}
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static int serial_tstc(struct console_device *cdev)
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{
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struct gs_port *port = container_of(cdev,
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struct gs_port, cdev);
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gs_start_rx(port);
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return (kfifo_len(port->recv_fifo) == 0) ? 0 : 1;
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}
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static int serial_getc(struct console_device *cdev)
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{
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struct gs_port *port = container_of(cdev,
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struct gs_port, cdev);
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unsigned char ch;
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uint64_t to;
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if (!port->port_usb)
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return -EIO;
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to = get_time_ns();
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while (kfifo_getc(port->recv_fifo, &ch)) {
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usb_gadget_poll();
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if (is_timeout(to, 300 * MSECOND))
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goto timeout;
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}
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gs_start_rx(port);
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return ch;
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timeout:
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gs_start_rx(port);
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return -ETIMEDOUT;
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}
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static void serial_flush(struct console_device *cdev)
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{
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}
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static int serial_setbaudrate(struct console_device *cdev, int baudrate)
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{
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return 0;
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}
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/**
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* gserial_connect - notify TTY I/O glue that USB link is active
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* @gser: the function, set up with endpoints and descriptors
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* @port_num: which port is active
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* Context: any (usually from irq)
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*
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* This is called activate endpoints and let the TTY layer know that
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* the connection is active ... not unlike "carrier detect". It won't
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* necessarily start I/O queues; unless the TTY is held open by any
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* task, there would be no point. However, the endpoints will be
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* activated so the USB host can perform I/O, subject to basic USB
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* hardware flow control.
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*
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* Caller needs to have set up the endpoints and USB function in @dev
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* before calling this, as well as the appropriate (speed-specific)
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* endpoint descriptors, and also have allocate @port_num by calling
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* @gserial_alloc_line().
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*
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* Returns negative errno or zero.
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* On success, ep->driver_data will be overwritten.
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*/
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int gserial_connect(struct gserial *gser, u8 port_num)
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{
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struct gs_port *port;
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int status;
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struct console_device *cdev;
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if (port_num >= MAX_U_SERIAL_PORTS)
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return -ENXIO;
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port = ports[port_num].port;
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if (!port) {
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pr_err("serial line %d not allocated.\n", port_num);
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return -EINVAL;
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}
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if (port->port_usb) {
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pr_err("serial line %d is in use.\n", port_num);
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return -EBUSY;
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}
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/* activate the endpoints */
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status = usb_ep_enable(gser->in);
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if (status < 0)
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return status;
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gser->in->driver_data = port;
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status = usb_ep_enable(gser->out);
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if (status < 0)
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goto fail_out;
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gser->out->driver_data = port;
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/* then tell the tty glue that I/O can work */
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gser->ioport = port;
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port->port_usb = gser;
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/* REVISIT unclear how best to handle this state...
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* we don't really couple it with the Linux TTY.
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*/
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gser->port_line_coding = port->port_line_coding;
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port->recv_fifo = kfifo_alloc(RECV_FIFO_SIZE);
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/*printf("gserial_connect: 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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cdev = &port->cdev;
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cdev->tstc = serial_tstc;
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cdev->putc = serial_putc;
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cdev->getc = serial_getc;
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cdev->flush = serial_flush;
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cdev->setbrg = serial_setbaudrate;
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cdev->devname = "usbserial";
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cdev->devid = DEVICE_ID_SINGLE;
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status = console_register(cdev);
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if (status)
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goto fail_out;
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dev_set_param(&cdev->class_dev, "active", "ioe");
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|
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/* REVISIT if waiting on "carrier detect", signal. */
|
|
|
|
/* if it's already open, start I/O ... and notify the serial
|
|
* protocol about open/close status (connect/disconnect).
|
|
*/
|
|
if (1) {
|
|
pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
|
|
if (gser->connect)
|
|
gser->connect(gser);
|
|
} else {
|
|
if (gser->disconnect)
|
|
gser->disconnect(gser);
|
|
}
|
|
|
|
return status;
|
|
|
|
fail_out:
|
|
usb_ep_disable(gser->in);
|
|
gser->in->driver_data = NULL;
|
|
return status;
|
|
}
|
|
EXPORT_SYMBOL_GPL(gserial_connect);
|
|
|
|
/**
|
|
* gserial_disconnect - notify TTY I/O glue that USB link is inactive
|
|
* @gser: the function, on which gserial_connect() was called
|
|
* Context: any (usually from irq)
|
|
*
|
|
* This is called to deactivate endpoints and let the TTY layer know
|
|
* that the connection went inactive ... not unlike "hangup".
|
|
*
|
|
* On return, the state is as if gserial_connect() had never been called;
|
|
* there is no active USB I/O on these endpoints.
|
|
*/
|
|
void gserial_disconnect(struct gserial *gser)
|
|
{
|
|
struct gs_port *port = gser->ioport;
|
|
struct console_device *cdev;
|
|
|
|
if (!port)
|
|
return;
|
|
|
|
cdev = &port->cdev;
|
|
|
|
/* tell the TTY glue not to do I/O here any more */
|
|
console_unregister(cdev);
|
|
|
|
/* REVISIT as above: how best to track this? */
|
|
port->port_line_coding = gser->port_line_coding;
|
|
|
|
port->port_usb = NULL;
|
|
gser->ioport = NULL;
|
|
|
|
/* disable endpoints, aborting down any active I/O */
|
|
usb_ep_disable(gser->out);
|
|
gser->out->driver_data = NULL;
|
|
|
|
usb_ep_disable(gser->in);
|
|
gser->in->driver_data = NULL;
|
|
|
|
/* finally, free any unused/unusable I/O buffers */
|
|
gs_free_requests(gser->out, &port->read_pool);
|
|
gs_free_requests(gser->in, &port->write_pool);
|
|
|
|
kfifo_free(port->recv_fifo);
|
|
}
|