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linux-zen-desktop/drivers/usb/gadget/function/u_serial.c

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// SPDX-License-Identifier: GPL-2.0+
/*
* u_serial.c - utilities for USB gadget "serial port"/TTY support
*
* Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
* Copyright (C) 2008 David Brownell
* Copyright (C) 2008 by Nokia Corporation
*
* This code also borrows from usbserial.c, which is
* Copyright (C) 1999 - 2002 Greg Kroah-Hartman (greg@kroah.com)
* Copyright (C) 2000 Peter Berger (pberger@brimson.com)
* Copyright (C) 2000 Al Borchers (alborchers@steinerpoint.com)
*/
/* #define VERBOSE_DEBUG */
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/module.h>
#include <linux/console.h>
#include <linux/kstrtox.h>
#include <linux/kthread.h>
#include <linux/workqueue.h>
#include <linux/kfifo.h>
#include "u_serial.h"
/*
* This component encapsulates the TTY layer glue needed to provide basic
* "serial port" functionality through the USB gadget stack. Each such
* port is exposed through a /dev/ttyGS* node.
*
* After this module has been loaded, the individual TTY port can be requested
* (gserial_alloc_line()) and it will stay available until they are removed
* (gserial_free_line()). Each one may be connected to a USB function
* (gserial_connect), or disconnected (with gserial_disconnect) when the USB
* host issues a config change event. Data can only flow when the port is
* connected to the host.
*
* A given TTY port can be made available in multiple configurations.
* For example, each one might expose a ttyGS0 node which provides a
* login application. In one case that might use CDC ACM interface 0,
* while another configuration might use interface 3 for that. The
* work to handle that (including descriptor management) is not part
* of this component.
*
* Configurations may expose more than one TTY port. For example, if
* ttyGS0 provides login service, then ttyGS1 might provide dialer access
* for a telephone or fax link. And ttyGS2 might be something that just
* needs a simple byte stream interface for some messaging protocol that
* is managed in userspace ... OBEX, PTP, and MTP have been mentioned.
*
*
* gserial is the lifecycle interface, used by USB functions
* gs_port is the I/O nexus, used by the tty driver
* tty_struct links to the tty/filesystem framework
*
* gserial <---> gs_port ... links will be null when the USB link is
* inactive; managed by gserial_{connect,disconnect}(). each gserial
* instance can wrap its own USB control protocol.
* gserial->ioport == usb_ep->driver_data ... gs_port
* gs_port->port_usb ... gserial
*
* gs_port <---> tty_struct ... links will be null when the TTY file
* isn't opened; managed by gs_open()/gs_close()
* gserial->port_tty ... tty_struct
* tty_struct->driver_data ... gserial
*/
/* RX and TX queues can buffer QUEUE_SIZE packets before they hit the
* next layer of buffering. For TX that's a circular buffer; for RX
* consider it a NOP. A third layer is provided by the TTY code.
*/
#define QUEUE_SIZE 16
#define WRITE_BUF_SIZE 8192 /* TX only */
#define GS_CONSOLE_BUF_SIZE 8192
/* Prevents race conditions while accessing gser->ioport */
static DEFINE_SPINLOCK(serial_port_lock);
/* console info */
struct gs_console {
struct console console;
struct work_struct work;
spinlock_t lock;
struct usb_request *req;
struct kfifo buf;
size_t missed;
};
/*
* The port structure holds info for each port, one for each minor number
* (and thus for each /dev/ node).
*/
struct gs_port {
struct tty_port port;
spinlock_t port_lock; /* guard port_* access */
struct gserial *port_usb;
#ifdef CONFIG_U_SERIAL_CONSOLE
struct gs_console *console;
#endif
u8 port_num;
struct list_head read_pool;
int read_started;
int read_allocated;
struct list_head read_queue;
unsigned n_read;
struct delayed_work push;
struct list_head write_pool;
int write_started;
int write_allocated;
struct kfifo port_write_buf;
wait_queue_head_t drain_wait; /* wait while writes drain */
bool write_busy;
wait_queue_head_t close_wait;
bool suspended; /* port suspended */
bool start_delayed; /* delay start when suspended */
/* REVISIT this state ... */
struct usb_cdc_line_coding port_line_coding; /* 8-N-1 etc */
};
static struct portmaster {
struct mutex lock; /* protect open/close */
struct gs_port *port;
} ports[MAX_U_SERIAL_PORTS];
#define GS_CLOSE_TIMEOUT 15 /* seconds */
#ifdef VERBOSE_DEBUG
#ifndef pr_vdebug
#define pr_vdebug(fmt, arg...) \
pr_debug(fmt, ##arg)
#endif /* pr_vdebug */
#else
#ifndef pr_vdebug
#define pr_vdebug(fmt, arg...) \
({ if (0) pr_debug(fmt, ##arg); })
#endif /* pr_vdebug */
#endif
/*-------------------------------------------------------------------------*/
/* I/O glue between TTY (upper) and USB function (lower) driver layers */
/*
* gs_alloc_req
*
* Allocate a usb_request and its buffer. Returns a pointer to the
* usb_request or NULL if there is an error.
*/
struct usb_request *
gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
{
struct usb_request *req;
req = usb_ep_alloc_request(ep, kmalloc_flags);
if (req != NULL) {
req->length = len;
req->buf = kmalloc(len, kmalloc_flags);
if (req->buf == NULL) {
usb_ep_free_request(ep, req);
return NULL;
}
}
return req;
}
EXPORT_SYMBOL_GPL(gs_alloc_req);
/*
* gs_free_req
*
* Free a usb_request and its buffer.
*/
void gs_free_req(struct usb_ep *ep, struct usb_request *req)
{
kfree(req->buf);
usb_ep_free_request(ep, req);
}
EXPORT_SYMBOL_GPL(gs_free_req);
/*
* gs_send_packet
*
* If there is data to send, a packet is built in the given
* buffer and the size is returned. If there is no data to
* send, 0 is returned.
*
* Called with port_lock held.
*/
static unsigned
gs_send_packet(struct gs_port *port, char *packet, unsigned size)
{
unsigned len;
len = kfifo_len(&port->port_write_buf);
if (len < size)
size = len;
if (size != 0)
size = kfifo_out(&port->port_write_buf, packet, size);
return size;
}
/*
* gs_start_tx
*
* This function finds available write requests, calls
* gs_send_packet to fill these packets with data, and
* continues until either there are no more write requests
* available or no more data to send. This function is
* run whenever data arrives or write requests are available.
*
* Context: caller owns port_lock; port_usb is non-null.
*/
static int gs_start_tx(struct gs_port *port)
/*
__releases(&port->port_lock)
__acquires(&port->port_lock)
*/
{
struct list_head *pool = &port->write_pool;
struct usb_ep *in;
int status = 0;
bool do_tty_wake = false;
if (!port->port_usb)
return status;
in = port->port_usb->in;
while (!port->write_busy && !list_empty(pool)) {
struct usb_request *req;
int len;
if (port->write_started >= QUEUE_SIZE)
break;
req = list_entry(pool->next, struct usb_request, list);
len = gs_send_packet(port, req->buf, in->maxpacket);
if (len == 0) {
wake_up_interruptible(&port->drain_wait);
break;
}
do_tty_wake = true;
req->length = len;
list_del(&req->list);
req->zero = kfifo_is_empty(&port->port_write_buf);
pr_vdebug("ttyGS%d: tx len=%d, %3ph ...\n", port->port_num, len, req->buf);
/* Drop lock while we call out of driver; completions
* could be issued while we do so. Disconnection may
* happen too; maybe immediately before we queue this!
*
* NOTE that we may keep sending data for a while after
* the TTY closed (dev->ioport->port_tty is NULL).
*/
port->write_busy = true;
spin_unlock(&port->port_lock);
status = usb_ep_queue(in, req, GFP_ATOMIC);
spin_lock(&port->port_lock);
port->write_busy = false;
if (status) {
pr_debug("%s: %s %s err %d\n",
__func__, "queue", in->name, status);
list_add(&req->list, pool);
break;
}
port->write_started++;
/* abort immediately after disconnect */
if (!port->port_usb)
break;
}
if (do_tty_wake && port->port.tty)
tty_wakeup(port->port.tty);
return status;
}
/*
* Context: caller owns port_lock, and port_usb is set
*/
static unsigned gs_start_rx(struct gs_port *port)
/*
__releases(&port->port_lock)
__acquires(&port->port_lock)
*/
{
struct list_head *pool = &port->read_pool;
struct usb_ep *out = port->port_usb->out;
while (!list_empty(pool)) {
struct usb_request *req;
int status;
struct tty_struct *tty;
/* no more rx if closed */
tty = port->port.tty;
if (!tty)
break;
if (port->read_started >= QUEUE_SIZE)
break;
req = list_entry(pool->next, struct usb_request, list);
list_del(&req->list);
req->length = out->maxpacket;
/* drop lock while we call out; the controller driver
* may need to call us back (e.g. for disconnect)
*/
spin_unlock(&port->port_lock);
status = usb_ep_queue(out, req, GFP_ATOMIC);
spin_lock(&port->port_lock);
if (status) {
pr_debug("%s: %s %s err %d\n",
__func__, "queue", out->name, status);
list_add(&req->list, pool);
break;
}
port->read_started++;
/* abort immediately after disconnect */
if (!port->port_usb)
break;
}
return port->read_started;
}
/*
* RX work takes data out of the RX queue and hands it up to the TTY
* layer until it refuses to take any more data (or is throttled back).
* Then it issues reads for any further data.
*
* If the RX queue becomes full enough that no usb_request is queued,
* the OUT endpoint may begin NAKing as soon as its FIFO fills up.
* So QUEUE_SIZE packets plus however many the FIFO holds (usually two)
* can be buffered before the TTY layer's buffers (currently 64 KB).
*/
static void gs_rx_push(struct work_struct *work)
{
struct delayed_work *w = to_delayed_work(work);
struct gs_port *port = container_of(w, struct gs_port, push);
struct tty_struct *tty;
struct list_head *queue = &port->read_queue;
bool disconnect = false;
bool do_push = false;
/* hand any queued data to the tty */
spin_lock_irq(&port->port_lock);
tty = port->port.tty;
while (!list_empty(queue)) {
struct usb_request *req;
req = list_first_entry(queue, struct usb_request, list);
/* leave data queued if tty was rx throttled */
if (tty && tty_throttled(tty))
break;
switch (req->status) {
case -ESHUTDOWN:
disconnect = true;
pr_vdebug("ttyGS%d: shutdown\n", port->port_num);
break;
default:
/* presumably a transient fault */
pr_warn("ttyGS%d: unexpected RX status %d\n",
port->port_num, req->status);
fallthrough;
case 0:
/* normal completion */
break;
}
/* push data to (open) tty */
if (req->actual && tty) {
char *packet = req->buf;
unsigned size = req->actual;
unsigned n;
int count;
/* we may have pushed part of this packet already... */
n = port->n_read;
if (n) {
packet += n;
size -= n;
}
count = tty_insert_flip_string(&port->port, packet,
size);
if (count)
do_push = true;
if (count != size) {
/* stop pushing; TTY layer can't handle more */
port->n_read += count;
pr_vdebug("ttyGS%d: rx block %d/%d\n",
port->port_num, count, req->actual);
break;
}
port->n_read = 0;
}
list_move(&req->list, &port->read_pool);
port->read_started--;
}
/* Push from tty to ldisc; this is handled by a workqueue,
* so we won't get callbacks and can hold port_lock
*/
if (do_push)
tty_flip_buffer_push(&port->port);
/* We want our data queue to become empty ASAP, keeping data
* in the tty and ldisc (not here). If we couldn't push any
* this time around, RX may be starved, so wait until next jiffy.
*
* We may leave non-empty queue only when there is a tty, and
* either it is throttled or there is no more room in flip buffer.
*/
if (!list_empty(queue) && !tty_throttled(tty))
schedule_delayed_work(&port->push, 1);
/* If we're still connected, refill the USB RX queue. */
if (!disconnect && port->port_usb)
gs_start_rx(port);
spin_unlock_irq(&port->port_lock);
}
static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
{
struct gs_port *port = ep->driver_data;
/* Queue all received data until the tty layer is ready for it. */
spin_lock(&port->port_lock);
list_add_tail(&req->list, &port->read_queue);
schedule_delayed_work(&port->push, 0);
spin_unlock(&port->port_lock);
}
static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
{
struct gs_port *port = ep->driver_data;
spin_lock(&port->port_lock);
list_add(&req->list, &port->write_pool);
port->write_started--;
switch (req->status) {
default:
/* presumably a transient fault */
pr_warn("%s: unexpected %s status %d\n",
__func__, ep->name, req->status);
fallthrough;
case 0:
/* normal completion */
gs_start_tx(port);
break;
case -ESHUTDOWN:
/* disconnect */
pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
break;
}
spin_unlock(&port->port_lock);
}
static void gs_free_requests(struct usb_ep *ep, struct list_head *head,
int *allocated)
{
struct usb_request *req;
while (!list_empty(head)) {
req = list_entry(head->next, struct usb_request, list);
list_del(&req->list);
gs_free_req(ep, req);
if (allocated)
(*allocated)--;
}
}
static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
void (*fn)(struct usb_ep *, struct usb_request *),
int *allocated)
{
int i;
struct usb_request *req;
int n = allocated ? QUEUE_SIZE - *allocated : QUEUE_SIZE;
/* Pre-allocate up to QUEUE_SIZE transfers, but if we can't
* do quite that many this time, don't fail ... we just won't
* be as speedy as we might otherwise be.
*/
for (i = 0; i < n; i++) {
req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
if (!req)
return list_empty(head) ? -ENOMEM : 0;
req->complete = fn;
list_add_tail(&req->list, head);
if (allocated)
(*allocated)++;
}
return 0;
}
/**
* gs_start_io - start USB I/O streams
* @port: port to use
* Context: holding port_lock; port_tty and port_usb are non-null
*
* We only start I/O when something is connected to both sides of
* this port. If nothing is listening on the host side, we may
* be pointlessly filling up our TX buffers and FIFO.
*/
static int gs_start_io(struct gs_port *port)
{
struct list_head *head = &port->read_pool;
struct usb_ep *ep = port->port_usb->out;
int status;
unsigned started;
/* Allocate RX and TX I/O buffers. We can't easily do this much
* earlier (with GFP_KERNEL) because the requests are coupled to
* endpoints, as are the packet sizes we'll be using. Different
* configurations may use different endpoints with a given port;
* and high speed vs full speed changes packet sizes too.
*/
status = gs_alloc_requests(ep, head, gs_read_complete,
&port->read_allocated);
if (status)
return status;
status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
gs_write_complete, &port->write_allocated);
if (status) {
gs_free_requests(ep, head, &port->read_allocated);
return status;
}
/* queue read requests */
port->n_read = 0;
started = gs_start_rx(port);
if (started) {
gs_start_tx(port);
/* Unblock any pending writes into our circular buffer, in case
* we didn't in gs_start_tx() */
tty_wakeup(port->port.tty);
} else {
gs_free_requests(ep, head, &port->read_allocated);
gs_free_requests(port->port_usb->in, &port->write_pool,
&port->write_allocated);
status = -EIO;
}
return status;
}
/*-------------------------------------------------------------------------*/
/* TTY Driver */
/*
* gs_open sets up the link between a gs_port and its associated TTY.
* That link is broken *only* by TTY close(), and all driver methods
* know that.
*/
static int gs_open(struct tty_struct *tty, struct file *file)
{
int port_num = tty->index;
struct gs_port *port;
int status = 0;
mutex_lock(&ports[port_num].lock);
port = ports[port_num].port;
if (!port) {
status = -ENODEV;
goto out;
}
spin_lock_irq(&port->port_lock);
/* allocate circular buffer on first open */
if (!kfifo_initialized(&port->port_write_buf)) {
spin_unlock_irq(&port->port_lock);
/*
* portmaster's mutex still protects from simultaneous open(),
* and close() can't happen, yet.
*/
status = kfifo_alloc(&port->port_write_buf,
WRITE_BUF_SIZE, GFP_KERNEL);
if (status) {
pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
port_num, tty, file);
goto out;
}
spin_lock_irq(&port->port_lock);
}
/* already open? Great. */
if (port->port.count++)
goto exit_unlock_port;
tty->driver_data = port;
port->port.tty = tty;
/* if connected, start the I/O stream */
if (port->port_usb) {
/* if port is suspended, wait resume to start I/0 stream */
if (!port->suspended) {
struct gserial *gser = port->port_usb;
pr_debug("gs_open: start ttyGS%d\n", port->port_num);
gs_start_io(port);
if (gser->connect)
gser->connect(gser);
} else {
pr_debug("delay start of ttyGS%d\n", port->port_num);
port->start_delayed = true;
}
}
pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
exit_unlock_port:
spin_unlock_irq(&port->port_lock);
out:
mutex_unlock(&ports[port_num].lock);
return status;
}
static int gs_close_flush_done(struct gs_port *p)
{
int cond;
/* return true on disconnect or empty buffer or if raced with open() */
spin_lock_irq(&p->port_lock);
cond = p->port_usb == NULL || !kfifo_len(&p->port_write_buf) ||
p->port.count > 1;
spin_unlock_irq(&p->port_lock);
return cond;
}
static void gs_close(struct tty_struct *tty, struct file *file)
{
struct gs_port *port = tty->driver_data;
struct gserial *gser;
spin_lock_irq(&port->port_lock);
if (port->port.count != 1) {
raced_with_open:
if (port->port.count == 0)
WARN_ON(1);
else
--port->port.count;
goto exit;
}
pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
gser = port->port_usb;
if (gser && !port->suspended && gser->disconnect)
gser->disconnect(gser);
/* wait for circular write buffer to drain, disconnect, or at
* most GS_CLOSE_TIMEOUT seconds; then discard the rest
*/
if (kfifo_len(&port->port_write_buf) > 0 && gser) {
spin_unlock_irq(&port->port_lock);
wait_event_interruptible_timeout(port->drain_wait,
gs_close_flush_done(port),
GS_CLOSE_TIMEOUT * HZ);
spin_lock_irq(&port->port_lock);
if (port->port.count != 1)
goto raced_with_open;
gser = port->port_usb;
}
/* Iff we're disconnected, there can be no I/O in flight so it's
* ok to free the circular buffer; else just scrub it. And don't
* let the push async work fire again until we're re-opened.
*/
if (gser == NULL)
kfifo_free(&port->port_write_buf);
else
kfifo_reset(&port->port_write_buf);
port->start_delayed = false;
port->port.count = 0;
port->port.tty = NULL;
pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
port->port_num, tty, file);
wake_up(&port->close_wait);
exit:
spin_unlock_irq(&port->port_lock);
}
static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
struct gs_port *port = tty->driver_data;
unsigned long flags;
pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n",
port->port_num, tty, count);
spin_lock_irqsave(&port->port_lock, flags);
if (count)
count = kfifo_in(&port->port_write_buf, buf, count);
/* treat count == 0 as flush_chars() */
if (port->port_usb)
gs_start_tx(port);
spin_unlock_irqrestore(&port->port_lock, flags);
return count;
}
static int gs_put_char(struct tty_struct *tty, unsigned char ch)
{
struct gs_port *port = tty->driver_data;
unsigned long flags;
int status;
pr_vdebug("gs_put_char: (%d,%p) char=0x%x, called from %ps\n",
port->port_num, tty, ch, __builtin_return_address(0));
spin_lock_irqsave(&port->port_lock, flags);
status = kfifo_put(&port->port_write_buf, ch);
spin_unlock_irqrestore(&port->port_lock, flags);
return status;
}
static void gs_flush_chars(struct tty_struct *tty)
{
struct gs_port *port = tty->driver_data;
unsigned long flags;
pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);
spin_lock_irqsave(&port->port_lock, flags);
if (port->port_usb)
gs_start_tx(port);
spin_unlock_irqrestore(&port->port_lock, flags);
}
static unsigned int gs_write_room(struct tty_struct *tty)
{
struct gs_port *port = tty->driver_data;
unsigned long flags;
unsigned int room = 0;
spin_lock_irqsave(&port->port_lock, flags);
if (port->port_usb)
room = kfifo_avail(&port->port_write_buf);
spin_unlock_irqrestore(&port->port_lock, flags);
pr_vdebug("gs_write_room: (%d,%p) room=%u\n",
port->port_num, tty, room);
return room;
}
static unsigned int gs_chars_in_buffer(struct tty_struct *tty)
{
struct gs_port *port = tty->driver_data;
unsigned long flags;
unsigned int chars;
spin_lock_irqsave(&port->port_lock, flags);
chars = kfifo_len(&port->port_write_buf);
spin_unlock_irqrestore(&port->port_lock, flags);
pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%u\n",
port->port_num, tty, chars);
return chars;
}
/* undo side effects of setting TTY_THROTTLED */
static void gs_unthrottle(struct tty_struct *tty)
{
struct gs_port *port = tty->driver_data;
unsigned long flags;
spin_lock_irqsave(&port->port_lock, flags);
if (port->port_usb) {
/* Kickstart read queue processing. We don't do xon/xoff,
* rts/cts, or other handshaking with the host, but if the
* read queue backs up enough we'll be NAKing OUT packets.
*/
pr_vdebug("ttyGS%d: unthrottle\n", port->port_num);
schedule_delayed_work(&port->push, 0);
}
spin_unlock_irqrestore(&port->port_lock, flags);
}
static int gs_break_ctl(struct tty_struct *tty, int duration)
{
struct gs_port *port = tty->driver_data;
int status = 0;
struct gserial *gser;
pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n",
port->port_num, duration);
spin_lock_irq(&port->port_lock);
gser = port->port_usb;
if (gser && gser->send_break)
status = gser->send_break(gser, duration);
spin_unlock_irq(&port->port_lock);
return status;
}
static const struct tty_operations gs_tty_ops = {
.open = gs_open,
.close = gs_close,
.write = gs_write,
.put_char = gs_put_char,
.flush_chars = gs_flush_chars,
.write_room = gs_write_room,
.chars_in_buffer = gs_chars_in_buffer,
.unthrottle = gs_unthrottle,
.break_ctl = gs_break_ctl,
};
/*-------------------------------------------------------------------------*/
static struct tty_driver *gs_tty_driver;
#ifdef CONFIG_U_SERIAL_CONSOLE
static void gs_console_complete_out(struct usb_ep *ep, struct usb_request *req)
{
struct gs_console *cons = req->context;
switch (req->status) {
default:
pr_warn("%s: unexpected %s status %d\n",
__func__, ep->name, req->status);
fallthrough;
case 0:
/* normal completion */
spin_lock(&cons->lock);
req->length = 0;
schedule_work(&cons->work);
spin_unlock(&cons->lock);
break;
case -ECONNRESET:
case -ESHUTDOWN:
/* disconnect */
pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
break;
}
}
static void __gs_console_push(struct gs_console *cons)
{
struct usb_request *req = cons->req;
struct usb_ep *ep;
size_t size;
if (!req)
return; /* disconnected */
if (req->length)
return; /* busy */
ep = cons->console.data;
size = kfifo_out(&cons->buf, req->buf, ep->maxpacket);
if (!size)
return;
if (cons->missed && ep->maxpacket >= 64) {
char buf[64];
size_t len;
len = sprintf(buf, "\n[missed %zu bytes]\n", cons->missed);
kfifo_in(&cons->buf, buf, len);
cons->missed = 0;
}
req->length = size;
if (usb_ep_queue(ep, req, GFP_ATOMIC))
req->length = 0;
}
static void gs_console_work(struct work_struct *work)
{
struct gs_console *cons = container_of(work, struct gs_console, work);
spin_lock_irq(&cons->lock);
__gs_console_push(cons);
spin_unlock_irq(&cons->lock);
}
static void gs_console_write(struct console *co,
const char *buf, unsigned count)
{
struct gs_console *cons = container_of(co, struct gs_console, console);
unsigned long flags;
size_t n;
spin_lock_irqsave(&cons->lock, flags);
n = kfifo_in(&cons->buf, buf, count);
if (n < count)
cons->missed += count - n;
if (cons->req && !cons->req->length)
schedule_work(&cons->work);
spin_unlock_irqrestore(&cons->lock, flags);
}
static struct tty_driver *gs_console_device(struct console *co, int *index)
{
*index = co->index;
return gs_tty_driver;
}
static int gs_console_connect(struct gs_port *port)
{
struct gs_console *cons = port->console;
struct usb_request *req;
struct usb_ep *ep;
if (!cons)
return 0;
ep = port->port_usb->in;
req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
if (!req)
return -ENOMEM;
req->complete = gs_console_complete_out;
req->context = cons;
req->length = 0;
spin_lock(&cons->lock);
cons->req = req;
cons->console.data = ep;
spin_unlock(&cons->lock);
pr_debug("ttyGS%d: console connected!\n", port->port_num);
schedule_work(&cons->work);
return 0;
}
static void gs_console_disconnect(struct gs_port *port)
{
struct gs_console *cons = port->console;
struct usb_request *req;
struct usb_ep *ep;
if (!cons)
return;
spin_lock(&cons->lock);
req = cons->req;
ep = cons->console.data;
cons->req = NULL;
spin_unlock(&cons->lock);
if (!req)
return;
usb_ep_dequeue(ep, req);
gs_free_req(ep, req);
}
static int gs_console_init(struct gs_port *port)
{
struct gs_console *cons;
int err;
if (port->console)
return 0;
cons = kzalloc(sizeof(*port->console), GFP_KERNEL);
if (!cons)
return -ENOMEM;
strcpy(cons->console.name, "ttyGS");
cons->console.write = gs_console_write;
cons->console.device = gs_console_device;
cons->console.flags = CON_PRINTBUFFER;
cons->console.index = port->port_num;
INIT_WORK(&cons->work, gs_console_work);
spin_lock_init(&cons->lock);
err = kfifo_alloc(&cons->buf, GS_CONSOLE_BUF_SIZE, GFP_KERNEL);
if (err) {
pr_err("ttyGS%d: allocate console buffer failed\n", port->port_num);
kfree(cons);
return err;
}
port->console = cons;
register_console(&cons->console);
spin_lock_irq(&port->port_lock);
if (port->port_usb)
gs_console_connect(port);
spin_unlock_irq(&port->port_lock);
return 0;
}
static void gs_console_exit(struct gs_port *port)
{
struct gs_console *cons = port->console;
if (!cons)
return;
unregister_console(&cons->console);
spin_lock_irq(&port->port_lock);
if (cons->req)
gs_console_disconnect(port);
spin_unlock_irq(&port->port_lock);
cancel_work_sync(&cons->work);
kfifo_free(&cons->buf);
kfree(cons);
port->console = NULL;
}
ssize_t gserial_set_console(unsigned char port_num, const char *page, size_t count)
{
struct gs_port *port;
bool enable;
int ret;
ret = kstrtobool(page, &enable);
if (ret)
return ret;
mutex_lock(&ports[port_num].lock);
port = ports[port_num].port;
if (WARN_ON(port == NULL)) {
ret = -ENXIO;
goto out;
}
if (enable)
ret = gs_console_init(port);
else
gs_console_exit(port);
out:
mutex_unlock(&ports[port_num].lock);
return ret < 0 ? ret : count;
}
EXPORT_SYMBOL_GPL(gserial_set_console);
ssize_t gserial_get_console(unsigned char port_num, char *page)
{
struct gs_port *port;
ssize_t ret;
mutex_lock(&ports[port_num].lock);
port = ports[port_num].port;
if (WARN_ON(port == NULL))
ret = -ENXIO;
else
ret = sprintf(page, "%u\n", !!port->console);
mutex_unlock(&ports[port_num].lock);
return ret;
}
EXPORT_SYMBOL_GPL(gserial_get_console);
#else
static int gs_console_connect(struct gs_port *port)
{
return 0;
}
static void gs_console_disconnect(struct gs_port *port)
{
}
static int gs_console_init(struct gs_port *port)
{
return -ENOSYS;
}
static void gs_console_exit(struct gs_port *port)
{
}
#endif
static int
gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
{
struct gs_port *port;
int ret = 0;
mutex_lock(&ports[port_num].lock);
if (ports[port_num].port) {
ret = -EBUSY;
goto out;
}
port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);
if (port == NULL) {
ret = -ENOMEM;
goto out;
}
tty_port_init(&port->port);
spin_lock_init(&port->port_lock);
init_waitqueue_head(&port->drain_wait);
init_waitqueue_head(&port->close_wait);
INIT_DELAYED_WORK(&port->push, gs_rx_push);
INIT_LIST_HEAD(&port->read_pool);
INIT_LIST_HEAD(&port->read_queue);
INIT_LIST_HEAD(&port->write_pool);
port->port_num = port_num;
port->port_line_coding = *coding;
ports[port_num].port = port;
out:
mutex_unlock(&ports[port_num].lock);
return ret;
}
static int gs_closed(struct gs_port *port)
{
int cond;
spin_lock_irq(&port->port_lock);
cond = port->port.count == 0;
spin_unlock_irq(&port->port_lock);
return cond;
}
static void gserial_free_port(struct gs_port *port)
{
cancel_delayed_work_sync(&port->push);
/* wait for old opens to finish */
wait_event(port->close_wait, gs_closed(port));
WARN_ON(port->port_usb != NULL);
tty_port_destroy(&port->port);
kfree(port);
}
void gserial_free_line(unsigned char port_num)
{
struct gs_port *port;
mutex_lock(&ports[port_num].lock);
if (!ports[port_num].port) {
mutex_unlock(&ports[port_num].lock);
return;
}
port = ports[port_num].port;
gs_console_exit(port);
ports[port_num].port = NULL;
mutex_unlock(&ports[port_num].lock);
gserial_free_port(port);
tty_unregister_device(gs_tty_driver, port_num);
}
EXPORT_SYMBOL_GPL(gserial_free_line);
int gserial_alloc_line_no_console(unsigned char *line_num)
{
struct usb_cdc_line_coding coding;
struct gs_port *port;
struct device *tty_dev;
int ret;
int port_num;
coding.dwDTERate = cpu_to_le32(9600);
coding.bCharFormat = 8;
coding.bParityType = USB_CDC_NO_PARITY;
coding.bDataBits = USB_CDC_1_STOP_BITS;
for (port_num = 0; port_num < MAX_U_SERIAL_PORTS; port_num++) {
ret = gs_port_alloc(port_num, &coding);
if (ret == -EBUSY)
continue;
if (ret)
return ret;
break;
}
if (ret)
return ret;
/* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
port = ports[port_num].port;
tty_dev = tty_port_register_device(&port->port,
gs_tty_driver, port_num, NULL);
if (IS_ERR(tty_dev)) {
pr_err("%s: failed to register tty for port %d, err %ld\n",
__func__, port_num, PTR_ERR(tty_dev));
ret = PTR_ERR(tty_dev);
mutex_lock(&ports[port_num].lock);
ports[port_num].port = NULL;
mutex_unlock(&ports[port_num].lock);
gserial_free_port(port);
goto err;
}
*line_num = port_num;
err:
return ret;
}
EXPORT_SYMBOL_GPL(gserial_alloc_line_no_console);
int gserial_alloc_line(unsigned char *line_num)
{
int ret = gserial_alloc_line_no_console(line_num);
if (!ret && !*line_num)
gs_console_init(ports[*line_num].port);
return ret;
}
EXPORT_SYMBOL_GPL(gserial_alloc_line);
/**
* gserial_connect - notify TTY I/O glue that USB link is active
* @gser: the function, set up with endpoints and descriptors
* @port_num: which port is active
* Context: any (usually from irq)
*
* This is called activate endpoints and let the TTY layer know that
* the connection is active ... not unlike "carrier detect". It won't
* necessarily start I/O queues; unless the TTY is held open by any
* task, there would be no point. However, the endpoints will be
* activated so the USB host can perform I/O, subject to basic USB
* hardware flow control.
*
* Caller needs to have set up the endpoints and USB function in @dev
* before calling this, as well as the appropriate (speed-specific)
* endpoint descriptors, and also have allocate @port_num by calling
* @gserial_alloc_line().
*
* Returns negative errno or zero.
* On success, ep->driver_data will be overwritten.
*/
int gserial_connect(struct gserial *gser, u8 port_num)
{
struct gs_port *port;
unsigned long flags;
int status;
if (port_num >= MAX_U_SERIAL_PORTS)
return -ENXIO;
port = ports[port_num].port;
if (!port) {
pr_err("serial line %d not allocated.\n", port_num);
return -EINVAL;
}
if (port->port_usb) {
pr_err("serial line %d is in use.\n", port_num);
return -EBUSY;
}
/* activate the endpoints */
status = usb_ep_enable(gser->in);
if (status < 0)
return status;
gser->in->driver_data = port;
status = usb_ep_enable(gser->out);
if (status < 0)
goto fail_out;
gser->out->driver_data = port;
/* then tell the tty glue that I/O can work */
spin_lock_irqsave(&port->port_lock, flags);
gser->ioport = port;
port->port_usb = gser;
/* REVISIT unclear how best to handle this state...
* we don't really couple it with the Linux TTY.
*/
gser->port_line_coding = port->port_line_coding;
/* 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 (port->port.count) {
pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
gs_start_io(port);
if (gser->connect)
gser->connect(gser);
} else {
if (gser->disconnect)
gser->disconnect(gser);
}
status = gs_console_connect(port);
spin_unlock_irqrestore(&port->port_lock, flags);
return status;
fail_out:
usb_ep_disable(gser->in);
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;
unsigned long flags;
if (!port)
return;
spin_lock_irqsave(&serial_port_lock, flags);
/* tell the TTY glue not to do I/O here any more */
spin_lock(&port->port_lock);
gs_console_disconnect(port);
/* REVISIT as above: how best to track this? */
port->port_line_coding = gser->port_line_coding;
port->port_usb = NULL;
gser->ioport = NULL;
if (port->port.count > 0) {
wake_up_interruptible(&port->drain_wait);
if (port->port.tty)
tty_hangup(port->port.tty);
}
port->suspended = false;
spin_unlock(&port->port_lock);
spin_unlock_irqrestore(&serial_port_lock, flags);
/* disable endpoints, aborting down any active I/O */
usb_ep_disable(gser->out);
usb_ep_disable(gser->in);
/* finally, free any unused/unusable I/O buffers */
spin_lock_irqsave(&port->port_lock, flags);
if (port->port.count == 0)
kfifo_free(&port->port_write_buf);
gs_free_requests(gser->out, &port->read_pool, NULL);
gs_free_requests(gser->out, &port->read_queue, NULL);
gs_free_requests(gser->in, &port->write_pool, NULL);
port->read_allocated = port->read_started =
port->write_allocated = port->write_started = 0;
spin_unlock_irqrestore(&port->port_lock, flags);
}
EXPORT_SYMBOL_GPL(gserial_disconnect);
void gserial_suspend(struct gserial *gser)
{
struct gs_port *port = gser->ioport;
unsigned long flags;
spin_lock_irqsave(&port->port_lock, flags);
port->suspended = true;
spin_unlock_irqrestore(&port->port_lock, flags);
}
EXPORT_SYMBOL_GPL(gserial_suspend);
void gserial_resume(struct gserial *gser)
{
struct gs_port *port;
unsigned long flags;
spin_lock_irqsave(&serial_port_lock, flags);
port = gser->ioport;
if (!port) {
spin_unlock_irqrestore(&serial_port_lock, flags);
return;
}
spin_lock(&port->port_lock);
spin_unlock(&serial_port_lock);
port->suspended = false;
if (!port->start_delayed) {
spin_unlock_irqrestore(&port->port_lock, flags);
return;
}
pr_debug("delayed start ttyGS%d\n", port->port_num);
gs_start_io(port);
if (gser->connect)
gser->connect(gser);
port->start_delayed = false;
spin_unlock_irqrestore(&port->port_lock, flags);
}
EXPORT_SYMBOL_GPL(gserial_resume);
static int __init userial_init(void)
{
struct tty_driver *driver;
unsigned i;
int status;
driver = tty_alloc_driver(MAX_U_SERIAL_PORTS, TTY_DRIVER_REAL_RAW |
TTY_DRIVER_DYNAMIC_DEV);
if (IS_ERR(driver))
return PTR_ERR(driver);
driver->driver_name = "g_serial";
driver->name = "ttyGS";
/* uses dynamically assigned dev_t values */
driver->type = TTY_DRIVER_TYPE_SERIAL;
driver->subtype = SERIAL_TYPE_NORMAL;
driver->init_termios = tty_std_termios;
/* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on
* MS-Windows. Otherwise, most of these flags shouldn't affect
* anything unless we were to actually hook up to a serial line.
*/
driver->init_termios.c_cflag =
B9600 | CS8 | CREAD | HUPCL | CLOCAL;
driver->init_termios.c_ispeed = 9600;
driver->init_termios.c_ospeed = 9600;
tty_set_operations(driver, &gs_tty_ops);
for (i = 0; i < MAX_U_SERIAL_PORTS; i++)
mutex_init(&ports[i].lock);
/* export the driver ... */
status = tty_register_driver(driver);
if (status) {
pr_err("%s: cannot register, err %d\n",
__func__, status);
goto fail;
}
gs_tty_driver = driver;
pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
MAX_U_SERIAL_PORTS,
(MAX_U_SERIAL_PORTS == 1) ? "" : "s");
return status;
fail:
tty_driver_kref_put(driver);
return status;
}
module_init(userial_init);
static void __exit userial_cleanup(void)
{
tty_unregister_driver(gs_tty_driver);
tty_driver_kref_put(gs_tty_driver);
gs_tty_driver = NULL;
}
module_exit(userial_cleanup);
MODULE_LICENSE("GPL");
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