/*
* 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)
*
* This software is distributed under the terms of the GNU General
* Public License ("GPL") as published by the Free Software Foundation,
* either version 2 of that License or (at your option) any later version.
*/
/* #define VERBOSE_DEBUG */
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/tty.h>
#include <linux/tty_flip.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 initialization (gserial_setup), these TTY port devices stay
* available until they are removed (gserial_cleanup). 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.
*/
#define PREFIX "ttyGS"
/*
* 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 */
/* circular buffer */
struct gs_buf {
unsigned buf_size;
char *buf_buf;
char *buf_get;
char *buf_put;
};
/*
* The port structure holds info for each port, one for each minor number
* (and thus for each /dev/ node).
*/
struct gs_port {
spinlock_t port_lock; /* guard port_* access */
struct gserial *port_usb;
struct tty_struct *port_tty;
unsigned open_count;
bool openclose; /* open/close in progress */
u8 port_num;
wait_queue_head_t close_wait; /* wait for last close */
struct list_head read_pool;
struct list_head read_queue;
unsigned n_read;
struct tasklet_struct push;
struct list_head write_pool;
struct gs_buf port_write_buf;
wait_queue_head_t drain_wait; /* wait while writes drain */
/* REVISIT this state ... */
struct usb_cdc_line_coding port_line_coding; /* 8-N-1 etc */
};
/* increase N_PORTS if you need more */
#define N_PORTS 4
static struct portmaster {
struct mutex lock; /* protect open/close */
struct gs_port *port;
} ports[N_PORTS];
static unsigned n_ports;
#define GS_CLOSE_TIMEOUT 15 /* seconds */
#ifdef VERBOSE_DEBUG
#define pr_vdebug(fmt, arg...) \
pr_debug(fmt, ##arg)
#else
#define pr_vdebug(fmt, arg...) \
({ if (0) pr_debug(fmt, ##arg); })
#endif
/*-------------------------------------------------------------------------*/
/* Circular Buffer */
/*
* gs_buf_alloc
*
* Allocate a circular buffer and all associated memory.
*/
static int gs_buf_alloc(struct gs_buf *gb, unsigned size)
{
gb->buf_buf = kmalloc(size, GFP_KERNEL);
if (gb->buf_buf == NULL)
return -ENOMEM;
gb->buf_size = size;
gb->buf_put = gb->buf_buf;
gb->buf_get = gb->buf_buf;
return 0;
}
/*
* gs_buf_free
*
* Free the buffer and all associated memory.
*/
static void gs_buf_free(struct gs_buf *gb)
{
kfree(gb->buf_buf);
gb->buf_buf = NULL;
}
/*
* gs_buf_clear
*
* Clear out all data in the circular buffer.
*/
static void gs_buf_clear(struct gs_buf *gb)
{
gb->buf_get = gb->buf_put;
/* equivalent to a get of all data available */
}
/*
* gs_buf_data_avail
*
* Return the number of bytes of data written into the circular
* buffer.
*/
static unsigned gs_buf_data_avail(struct gs_buf *gb)
{
return (gb->buf_size + gb->buf_put - gb->buf_get) % gb->buf_size;
}
/*
* gs_buf_space_avail
*
* Return the number of bytes of space available in the circular
* buffer.
*/
static unsigned gs_buf_space_avail(struct gs_buf *gb)
{
return (gb->buf_size + gb->buf_get - gb->buf_put - 1) % gb->buf_size;
}
/*
* gs_buf_put
*
* Copy data data from a user buffer and put it into the circular buffer.
* Restrict to the amount of space available.
*
* Return the number of bytes copied.
*/
static unsigned
gs_buf_put(struct gs_buf *gb, const char *buf, unsigned count)
{
unsigned len;
len = gs_buf_space_avail(gb);
if (count > len)
count = len;
if (count == 0)
return 0;
len = gb->buf_buf + gb->buf_size - gb->buf_put;
if (count > len) {
memcpy(gb->buf_put, buf, len);
memcpy(gb->buf_buf, buf+len, count - len);
gb->buf_put = gb->buf_buf + count - len;
} else {
memcpy(gb->buf_put, buf, count);
if (count < len)
gb->buf_put += count;
else /* count == len */
gb->buf_put = gb->buf_buf;
}
return count;
}
/*
* gs_buf_get
*
* Get data from the circular buffer and copy to the given buffer.
* Restrict to the amount of data available.
*
* Return the number of bytes copied.
*/
static unsigned
gs_buf_get(struct gs_buf *gb, char *buf, unsigned count)
{
unsigned len;
len = gs_buf_data_avail(gb);
if (count > len)
count = len;
if (count == 0)
return 0;
len = gb->buf_buf + gb->buf_size - gb->buf_get;
if (count > len) {
memcpy(buf, gb->buf_get, len);
memcpy(buf+len, gb->buf_buf, count - len);
gb->buf_get = gb->buf_buf + count - len;
} else {
memcpy(buf, gb->buf_get, count);
if (count < len)
gb->buf_get += count;
else /* count == len */
gb->buf_get = gb->buf_buf;
}
return count;
}
/*-------------------------------------------------------------------------*/
/* 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;
}
/*
* 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);
}
/*
* 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 = gs_buf_data_avail(&port->port_write_buf);
if (len < size)
size = len;
if (size != 0)
size = gs_buf_get(&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 = port->port_usb->in;
int status = 0;
bool do_tty_wake = false;
while (!list_empty(pool)) {
struct usb_request *req;
int len;
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);
pr_vdebug(PREFIX "%d: tx len=%d, 0x%02x 0x%02x 0x%02x ...\n",
port->port_num, len, *((u8 *)req->buf),
*((u8 *)req->buf+1), *((u8 *)req->buf+2));
/* 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).
*/
spin_unlock(&port->port_lock);
status = usb_ep_queue(in, req, GFP_ATOMIC);
spin_lock(&port->port_lock);
if (status) {
pr_debug("%s: %s %s err %d\n",
__func__, "queue", in->name, status);
list_add(&req->list, pool);
break;
}
/* 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;
unsigned started = 0;
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;
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;
}
started++;
/* abort immediately after disconnect */
if (!port->port_usb)
break;
}
return started;
}
/*
* RX tasklet 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(unsigned long _port)
{
struct gs_port *port = (void *)_port;
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);
/* discard data if tty was closed */
if (!tty)
goto recycle;
/* leave data queued if tty was rx throttled */
if (test_bit(TTY_THROTTLED, &tty->flags))
break;
switch (req->status) {
case -ESHUTDOWN:
disconnect = true;
pr_vdebug(PREFIX "%d: shutdown\n", port->port_num);
break;
default:
/* presumably a transient fault */
pr_warning(PREFIX "%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) {
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(tty, packet, size);
if (count)
do_push = true;
if (count != size) {
/* stop pushing; TTY layer can't handle more */
port->n_read += count;
pr_vdebug(PREFIX "%d: rx block %d/%d\n",
port->port_num,
count, req->actual);
break;
}
port->n_read = 0;
}
recycle:
list_move(&req->list, &port->read_pool);
}
/* Push from tty to ldisc; this is immediate with low_latency, and
* may trigger callbacks to this driver ... so drop the spinlock.
*/
if (tty && do_push) {
spin_unlock_irq(&port->port_lock);
tty_flip_buffer_push(tty);
wake_up_interruptible(&tty->read_wait);
spin_lock_irq(&port->port_lock);
/* tty may have been closed */
tty = port->port_tty;
}
/* 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, there may be trouble unless there's an
* implicit tty_unthrottle() call on its way...
*
* REVISIT we should probably add a timer to keep the tasklet
* from starving ... but it's not clear that case ever happens.
*/
if (!list_empty(queue) && tty) {
if (!test_bit(TTY_THROTTLED, &tty->flags)) {
if (do_push)
tasklet_schedule(&port->push);
else
pr_warning(PREFIX "%d: RX not scheduled?\n",
port->port_num);
}
}
/* 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);
tasklet_schedule(&port->push);
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);
switch (req->status) {
default:
/* presumably a transient fault */
pr_warning("%s: unexpected %s status %d\n",
__func__, ep->name, req->status);
/* FALL THROUGH */
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)
{
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);
}
}
static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
void (*fn)(struct usb_ep *, struct usb_request *))
{
int i;
struct usb_request *req;
/* 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 < QUEUE_SIZE; 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);
}
return 0;
}
/**
* gs_start_io - start USB I/O streams
* @dev: encapsulates endpoints 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);
if (status)
return status;
status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
gs_write_complete);
if (status) {
gs_free_requests(ep, head);
return status;
}
/* queue read requests */
port->n_read = 0;
started = gs_start_rx(port);
/* unblock any pending writes into our circular buffer */
if (started) {
tty_wakeup(port->port_tty);
} else {
gs_free_requests(ep, head);
gs_free_requests(port->port_usb->in, &port->write_pool);
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;
if (port_num < 0 || port_num >= n_ports)
return -ENXIO;
do {
mutex_lock(&ports[port_num].lock);
port = ports[port_num].port;
if (!port)
status = -ENODEV;
else {
spin_lock_irq(&port->port_lock);
/* already open? Great. */
if (port->open_count) {
status = 0;
port->open_count++;
/* currently opening/closing? wait ... */
} else if (port->openclose) {
status = -EBUSY;
/* ... else we do the work */
} else {
status = -EAGAIN;
port->openclose = true;
}
spin_unlock_irq(&port->port_lock);
}
mutex_unlock(&ports[port_num].lock);
switch (status) {
default:
/* fully handled */
return status;
case -EAGAIN:
/* must do the work */
break;
case -EBUSY:
/* wait for EAGAIN task to finish */
msleep(1);
/* REVISIT could have a waitchannel here, if
* concurrent open performance is important
*/
break;
}
} while (status != -EAGAIN);
/* Do the "real open" */
spin_lock_irq(&port->port_lock);
/* allocate circular buffer on first open */
if (port->port_write_buf.buf_buf == NULL) {
spin_unlock_irq(&port->port_lock);
status = gs_buf_alloc(&port->port_write_buf, WRITE_BUF_SIZE);
spin_lock_irq(&port->port_lock);
if (status) {
pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
port->port_num, tty, file);
port->openclose = false;
goto exit_unlock_port;
}
}
/* REVISIT if REMOVED (ports[].port NULL), abort the open
* to let rmmod work faster (but this way isn't wrong).
*/
/* REVISIT maybe wait for "carrier detect" */
tty->driver_data = port;
port->port_tty = tty;
port->open_count = 1;
port->openclose = false;
/* low_latency means ldiscs work in tasklet context, without
* needing a workqueue schedule ... easier to keep up.
*/
tty->low_latency = 1;
/* if connected, start the I/O stream */
if (port->port_usb) {
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);
}
pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
status = 0;
exit_unlock_port:
spin_unlock_irq(&port->port_lock);
return status;
}
static int gs_writes_finished(struct gs_port *p)
{
int cond;
/* return true on disconnect or empty buffer */
spin_lock_irq(&p->port_lock);
cond = (p->port_usb == NULL) || !gs_buf_data_avail(&p->port_write_buf);
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->open_count != 1) {
if (port->open_count == 0)
WARN_ON(1);
else
--port->open_count;
goto exit;
}
pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
/* mark port as closing but in use; we can drop port lock
* and sleep if necessary
*/
port->openclose = true;
port->open_count = 0;
gser = port->port_usb;
if (gser && 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 (gs_buf_data_avail(&port->port_write_buf) > 0 && gser) {
spin_unlock_irq(&port->port_lock);
wait_event_interruptible_timeout(port->drain_wait,
gs_writes_finished(port),
GS_CLOSE_TIMEOUT * HZ);
spin_lock_irq(&port->port_lock);
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 tasklet fire again until we're re-opened.
*/
if (gser == NULL)
gs_buf_free(&port->port_write_buf);
else
gs_buf_clear(&port->port_write_buf);
tty->driver_data = NULL;
port->port_tty = NULL;
port->openclose = false;
pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
port->port_num, tty, file);
wake_up_interruptible(&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;
int status;
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 = gs_buf_put(&port->port_write_buf, buf, count);
/* treat count == 0 as flush_chars() */
if (port->port_usb)
status = 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 %p\n",
port->port_num, tty, ch, __builtin_return_address(0));
spin_lock_irqsave(&port->port_lock, flags);
status = gs_buf_put(&port->port_write_buf, &ch, 1);
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 int gs_write_room(struct tty_struct *tty)
{
struct gs_port *port = tty->driver_data;
unsigned long flags;
int room = 0;
spin_lock_irqsave(&port->port_lock, flags);
if (port->port_usb)
room = gs_buf_space_avail(&port->port_write_buf);
spin_unlock_irqrestore(&port->port_lock, flags);
pr_vdebug("gs_write_room: (%d,%p) room=%d\n",
port->port_num, tty, room);
return room;
}
static int gs_chars_in_buffer(struct tty_struct *tty)
{
struct gs_port *port = tty->driver_data;
unsigned long flags;
int chars = 0;
spin_lock_irqsave(&port->port_lock, flags);
chars = gs_buf_data_avail(&port->port_write_buf);
spin_unlock_irqrestore(&port->port_lock, flags);
pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%d\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.
*/
tasklet_schedule(&port->push);
pr_vdebug(PREFIX "%d: unthrottle\n", port->port_num);
}
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;
static int __init
gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
{
struct gs_port *port;
port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);
if (port == NULL)
return -ENOMEM;
spin_lock_init(&port->port_lock);
init_waitqueue_head(&port->close_wait);
init_waitqueue_head(&port->drain_wait);
tasklet_init(&port->push, gs_rx_push, (unsigned long) port);
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;
return 0;
}
/**
* gserial_setup - initialize TTY driver for one or more ports
* @g: gadget to associate with these ports
* @count: how many ports to support
* Context: may sleep
*
* The TTY stack needs to know in advance how many devices it should
* plan to manage. Use this call to set up the ports you will be
* exporting through USB. Later, connect them to functions based
* on what configuration is activated by the USB host; and disconnect
* them as appropriate.
*
* An example would be a two-configuration device in which both
* configurations expose port 0, but through different functions.
* One configuration could even expose port 1 while the other
* one doesn't.
*
* Returns negative errno or zero.
*/
int __init gserial_setup(struct usb_gadget *g, unsigned count)
{
unsigned i;
struct usb_cdc_line_coding coding;
int status;
if (count == 0 || count > N_PORTS)
return -EINVAL;
gs_tty_driver = alloc_tty_driver(count);
if (!gs_tty_driver)
return -ENOMEM;
gs_tty_driver->owner = THIS_MODULE;
gs_tty_driver->driver_name = "g_serial";
gs_tty_driver->name = PREFIX;
/* uses dynamically assigned dev_t values */
gs_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
gs_tty_driver->subtype = SERIAL_TYPE_NORMAL;
gs_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
gs_tty_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.
*/
gs_tty_driver->init_termios.c_cflag =
B9600 | CS8 | CREAD | HUPCL | CLOCAL;
gs_tty_driver->init_termios.c_ispeed = 9600;
gs_tty_driver->init_termios.c_ospeed = 9600;
coding.dwDTERate = cpu_to_le32(9600);
coding.bCharFormat = 8;
coding.bParityType = USB_CDC_NO_PARITY;
coding.bDataBits = USB_CDC_1_STOP_BITS;
tty_set_operations(gs_tty_driver, &gs_tty_ops);
/* make devices be openable */
for (i = 0; i < count; i++) {
mutex_init(&ports[i].lock);
status = gs_port_alloc(i, &coding);
if (status) {
count = i;
goto fail;
}
}
n_ports = count;
/* export the driver ... */
status = tty_register_driver(gs_tty_driver);
if (status) {
put_tty_driver(gs_tty_driver);
pr_err("%s: cannot register, err %d\n",
__func__, status);
goto fail;
}
/* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
for (i = 0; i < count; i++) {
struct device *tty_dev;
tty_dev = tty_register_device(gs_tty_driver, i, &g->dev);
if (IS_ERR(tty_dev))
pr_warning("%s: no classdev for port %d, err %ld\n",
__func__, i, PTR_ERR(tty_dev));
}
pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
count, (count == 1) ? "" : "s");
return status;
fail:
while (count--)
kfree(ports[count].port);
put_tty_driver(gs_tty_driver);
gs_tty_driver = NULL;
return status;
}
static int gs_closed(struct gs_port *port)
{
int cond;
spin_lock_irq(&port->port_lock);
cond = (port->open_count == 0) && !port->openclose;
spin_unlock_irq(&port->port_lock);
return cond;
}
/**
* gserial_cleanup - remove TTY-over-USB driver and devices
* Context: may sleep
*
* This is called to free all resources allocated by @gserial_setup().
* Accordingly, it may need to wait until some open /dev/ files have
* closed.
*
* The caller must have issued @gserial_disconnect() for any ports
* that had previously been connected, so that there is never any
* I/O pending when it's called.
*/
void gserial_cleanup(void)
{
unsigned i;
struct gs_port *port;
if (!gs_tty_driver)
return;
/* start sysfs and /dev/ttyGS* node removal */
for (i = 0; i < n_ports; i++)
tty_unregister_device(gs_tty_driver, i);
for (i = 0; i < n_ports; i++) {
/* prevent new opens */
mutex_lock(&ports[i].lock);
port = ports[i].port;
ports[i].port = NULL;
mutex_unlock(&ports[i].lock);
tasklet_kill(&port->push);
/* wait for old opens to finish */
wait_event(port->close_wait, gs_closed(port));
WARN_ON(port->port_usb != NULL);
kfree(port);
}
n_ports = 0;
tty_unregister_driver(gs_tty_driver);
gs_tty_driver = NULL;
pr_debug("%s: cleaned up ttyGS* support\n", __func__);
}
/**
* 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 set up the TTY driver by calling
* @gserial_setup().
*
* 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 (!gs_tty_driver || port_num >= n_ports)
return -ENXIO;
/* we "know" gserial_cleanup() hasn't been called */
port = ports[port_num].port;
/* activate the endpoints */
status = usb_ep_enable(gser->in, gser->in_desc);
if (status < 0)
return status;
gser->in->driver_data = port;
status = usb_ep_enable(gser->out, gser->out_desc);
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->open_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);
}
spin_unlock_irqrestore(&port->port_lock, flags);
return status;
fail_out:
usb_ep_disable(gser->in);
gser->in->driver_data = NULL;
return status;
}
/**
* 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;
/* tell the TTY glue not to do I/O here any more */
spin_lock_irqsave(&port->port_lock, flags);
/* 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->open_count > 0 || port->openclose) {
wake_up_interruptible(&port->drain_wait);
if (port->port_tty)
tty_hangup(port->port_tty);
}
spin_unlock_irqrestore(&port->port_lock, flags);
/* 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 */
spin_lock_irqsave(&port->port_lock, flags);
if (port->open_count == 0 && !port->openclose)
gs_buf_free(&port->port_write_buf);
gs_free_requests(gser->out, &port->read_pool);
gs_free_requests(gser->out, &port->read_queue);
gs_free_requests(gser->in, &port->write_pool);
spin_unlock_irqrestore(&port->port_lock, flags);
}
