/* * 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 #include #include #include #include #include #include #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); req->zero = (gs_buf_data_avail(&port->port_write_buf) == 0); 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; without low_latency set this is handled by * a workqueue, so we won't get callbacks and can hold port_lock */ if (tty && do_push) { tty_flip_buffer_push(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; /* 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) { 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); }