// 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 #include #include #include #include #include #include #include #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 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 */ struct async_icount icount; /* 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; port->icount.tx += len; 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; } port->icount.rx += size; 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; int status; unsigned started; if (!port->port_usb || !port->port.tty) return -EIO; /* 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. */ ep = port->port_usb->out; 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 { /* Free reqs only if we are still connected */ if (port->port_usb) { 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 ssize_t gs_write(struct tty_struct *tty, const u8 *buf, size_t count) { struct gs_port *port = tty->driver_data; unsigned long flags; pr_vdebug("gs_write: ttyGS%d (%p) writing %zu 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, u8 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 int gs_get_icount(struct tty_struct *tty, struct serial_icounter_struct *icount) { struct gs_port *port = tty->driver_data; struct async_icount cnow; unsigned long flags; spin_lock_irqsave(&port->port_lock, flags); cnow = port->icount; spin_unlock_irqrestore(&port->port_lock, flags); icount->rx = cnow.rx; icount->tx = cnow.tx; return 0; } 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, .get_icount = gs_get_icount, }; /*-------------------------------------------------------------------------*/ 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; spin_unlock_irq(&cons->lock); if (usb_ep_queue(ep, req, GFP_ATOMIC)) req->length = 0; spin_lock_irq(&cons->lock); } 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; 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 = true; port->start_delayed = 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_DESCRIPTION("utilities for USB gadget \"serial port\"/TTY support"); MODULE_LICENSE("GPL");