summaryrefslogtreecommitdiffstats
path: root/drivers/usb/gadget/function/u_serial.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--drivers/usb/gadget/function/u_serial.c1534
1 files changed, 1534 insertions, 0 deletions
diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
new file mode 100644
index 000000000..3c51355cc
--- /dev/null
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -0,0 +1,1534 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * u_serial.c - utilities for USB gadget "serial port"/TTY support
+ *
+ * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
+ * Copyright (C) 2008 David Brownell
+ * Copyright (C) 2008 by Nokia Corporation
+ *
+ * This code also borrows from usbserial.c, which is
+ * Copyright (C) 1999 - 2002 Greg Kroah-Hartman (greg@kroah.com)
+ * Copyright (C) 2000 Peter Berger (pberger@brimson.com)
+ * Copyright (C) 2000 Al Borchers (alborchers@steinerpoint.com)
+ */
+
+/* #define VERBOSE_DEBUG */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/console.h>
+#include <linux/kthread.h>
+#include <linux/workqueue.h>
+#include <linux/kfifo.h>
+
+#include "u_serial.h"
+
+
+/*
+ * This component encapsulates the TTY layer glue needed to provide basic
+ * "serial port" functionality through the USB gadget stack. Each such
+ * port is exposed through a /dev/ttyGS* node.
+ *
+ * After this module has been loaded, the individual TTY port can be requested
+ * (gserial_alloc_line()) and it will stay available until they are removed
+ * (gserial_free_line()). Each one may be connected to a USB function
+ * (gserial_connect), or disconnected (with gserial_disconnect) when the USB
+ * host issues a config change event. Data can only flow when the port is
+ * connected to the host.
+ *
+ * A given TTY port can be made available in multiple configurations.
+ * For example, each one might expose a ttyGS0 node which provides a
+ * login application. In one case that might use CDC ACM interface 0,
+ * while another configuration might use interface 3 for that. The
+ * work to handle that (including descriptor management) is not part
+ * of this component.
+ *
+ * Configurations may expose more than one TTY port. For example, if
+ * ttyGS0 provides login service, then ttyGS1 might provide dialer access
+ * for a telephone or fax link. And ttyGS2 might be something that just
+ * needs a simple byte stream interface for some messaging protocol that
+ * is managed in userspace ... OBEX, PTP, and MTP have been mentioned.
+ *
+ *
+ * gserial is the lifecycle interface, used by USB functions
+ * gs_port is the I/O nexus, used by the tty driver
+ * tty_struct links to the tty/filesystem framework
+ *
+ * gserial <---> gs_port ... links will be null when the USB link is
+ * inactive; managed by gserial_{connect,disconnect}(). each gserial
+ * instance can wrap its own USB control protocol.
+ * gserial->ioport == usb_ep->driver_data ... gs_port
+ * gs_port->port_usb ... gserial
+ *
+ * gs_port <---> tty_struct ... links will be null when the TTY file
+ * isn't opened; managed by gs_open()/gs_close()
+ * gserial->port_tty ... tty_struct
+ * tty_struct->driver_data ... gserial
+ */
+
+/* RX and TX queues can buffer QUEUE_SIZE packets before they hit the
+ * next layer of buffering. For TX that's a circular buffer; for RX
+ * consider it a NOP. A third layer is provided by the TTY code.
+ */
+#define QUEUE_SIZE 16
+#define WRITE_BUF_SIZE 8192 /* TX only */
+#define GS_CONSOLE_BUF_SIZE 8192
+
+/* Prevents race conditions while accessing gser->ioport */
+static DEFINE_SPINLOCK(serial_port_lock);
+
+/* console info */
+struct gs_console {
+ struct console console;
+ struct work_struct work;
+ spinlock_t lock;
+ struct usb_request *req;
+ struct kfifo buf;
+ size_t missed;
+};
+
+/*
+ * The port structure holds info for each port, one for each minor number
+ * (and thus for each /dev/ node).
+ */
+struct gs_port {
+ struct tty_port port;
+ spinlock_t port_lock; /* guard port_* access */
+
+ struct gserial *port_usb;
+#ifdef CONFIG_U_SERIAL_CONSOLE
+ struct gs_console *console;
+#endif
+
+ u8 port_num;
+
+ struct list_head read_pool;
+ int read_started;
+ int read_allocated;
+ struct list_head read_queue;
+ unsigned n_read;
+ struct delayed_work push;
+
+ struct list_head write_pool;
+ int write_started;
+ int write_allocated;
+ struct kfifo port_write_buf;
+ wait_queue_head_t drain_wait; /* wait while writes drain */
+ bool write_busy;
+ wait_queue_head_t close_wait;
+ bool suspended; /* port suspended */
+ bool start_delayed; /* delay start when suspended */
+
+ /* REVISIT this state ... */
+ struct usb_cdc_line_coding port_line_coding; /* 8-N-1 etc */
+};
+
+static struct portmaster {
+ struct mutex lock; /* protect open/close */
+ struct gs_port *port;
+} ports[MAX_U_SERIAL_PORTS];
+
+#define GS_CLOSE_TIMEOUT 15 /* seconds */
+
+
+
+#ifdef VERBOSE_DEBUG
+#ifndef pr_vdebug
+#define pr_vdebug(fmt, arg...) \
+ pr_debug(fmt, ##arg)
+#endif /* pr_vdebug */
+#else
+#ifndef pr_vdebug
+#define pr_vdebug(fmt, arg...) \
+ ({ if (0) pr_debug(fmt, ##arg); })
+#endif /* pr_vdebug */
+#endif
+
+/*-------------------------------------------------------------------------*/
+
+/* I/O glue between TTY (upper) and USB function (lower) driver layers */
+
+/*
+ * gs_alloc_req
+ *
+ * Allocate a usb_request and its buffer. Returns a pointer to the
+ * usb_request or NULL if there is an error.
+ */
+struct usb_request *
+gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
+{
+ struct usb_request *req;
+
+ req = usb_ep_alloc_request(ep, kmalloc_flags);
+
+ if (req != NULL) {
+ req->length = len;
+ req->buf = kmalloc(len, kmalloc_flags);
+ if (req->buf == NULL) {
+ usb_ep_free_request(ep, req);
+ return NULL;
+ }
+ }
+
+ return req;
+}
+EXPORT_SYMBOL_GPL(gs_alloc_req);
+
+/*
+ * gs_free_req
+ *
+ * Free a usb_request and its buffer.
+ */
+void gs_free_req(struct usb_ep *ep, struct usb_request *req)
+{
+ kfree(req->buf);
+ usb_ep_free_request(ep, req);
+}
+EXPORT_SYMBOL_GPL(gs_free_req);
+
+/*
+ * gs_send_packet
+ *
+ * If there is data to send, a packet is built in the given
+ * buffer and the size is returned. If there is no data to
+ * send, 0 is returned.
+ *
+ * Called with port_lock held.
+ */
+static unsigned
+gs_send_packet(struct gs_port *port, char *packet, unsigned size)
+{
+ unsigned len;
+
+ len = kfifo_len(&port->port_write_buf);
+ if (len < size)
+ size = len;
+ if (size != 0)
+ size = kfifo_out(&port->port_write_buf, packet, size);
+ return size;
+}
+
+/*
+ * gs_start_tx
+ *
+ * This function finds available write requests, calls
+ * gs_send_packet to fill these packets with data, and
+ * continues until either there are no more write requests
+ * available or no more data to send. This function is
+ * run whenever data arrives or write requests are available.
+ *
+ * Context: caller owns port_lock; port_usb is non-null.
+ */
+static int gs_start_tx(struct gs_port *port)
+/*
+__releases(&port->port_lock)
+__acquires(&port->port_lock)
+*/
+{
+ struct list_head *pool = &port->write_pool;
+ struct usb_ep *in;
+ int status = 0;
+ bool do_tty_wake = false;
+
+ if (!port->port_usb)
+ return status;
+
+ in = port->port_usb->in;
+
+ while (!port->write_busy && !list_empty(pool)) {
+ struct usb_request *req;
+ int len;
+
+ if (port->write_started >= QUEUE_SIZE)
+ break;
+
+ req = list_entry(pool->next, struct usb_request, list);
+ len = gs_send_packet(port, req->buf, in->maxpacket);
+ if (len == 0) {
+ wake_up_interruptible(&port->drain_wait);
+ break;
+ }
+ do_tty_wake = true;
+
+ req->length = len;
+ list_del(&req->list);
+ req->zero = kfifo_is_empty(&port->port_write_buf);
+
+ pr_vdebug("ttyGS%d: tx len=%d, %3ph ...\n", port->port_num, len, req->buf);
+
+ /* Drop lock while we call out of driver; completions
+ * could be issued while we do so. Disconnection may
+ * happen too; maybe immediately before we queue this!
+ *
+ * NOTE that we may keep sending data for a while after
+ * the TTY closed (dev->ioport->port_tty is NULL).
+ */
+ port->write_busy = true;
+ spin_unlock(&port->port_lock);
+ status = usb_ep_queue(in, req, GFP_ATOMIC);
+ spin_lock(&port->port_lock);
+ port->write_busy = false;
+
+ if (status) {
+ pr_debug("%s: %s %s err %d\n",
+ __func__, "queue", in->name, status);
+ list_add(&req->list, pool);
+ break;
+ }
+
+ port->write_started++;
+
+ /* abort immediately after disconnect */
+ if (!port->port_usb)
+ break;
+ }
+
+ if (do_tty_wake && port->port.tty)
+ tty_wakeup(port->port.tty);
+ return status;
+}
+
+/*
+ * Context: caller owns port_lock, and port_usb is set
+ */
+static unsigned gs_start_rx(struct gs_port *port)
+/*
+__releases(&port->port_lock)
+__acquires(&port->port_lock)
+*/
+{
+ struct list_head *pool = &port->read_pool;
+ struct usb_ep *out = port->port_usb->out;
+
+ while (!list_empty(pool)) {
+ struct usb_request *req;
+ int status;
+ struct tty_struct *tty;
+
+ /* no more rx if closed */
+ tty = port->port.tty;
+ if (!tty)
+ break;
+
+ if (port->read_started >= QUEUE_SIZE)
+ break;
+
+ req = list_entry(pool->next, struct usb_request, list);
+ list_del(&req->list);
+ req->length = out->maxpacket;
+
+ /* drop lock while we call out; the controller driver
+ * may need to call us back (e.g. for disconnect)
+ */
+ spin_unlock(&port->port_lock);
+ status = usb_ep_queue(out, req, GFP_ATOMIC);
+ spin_lock(&port->port_lock);
+
+ if (status) {
+ pr_debug("%s: %s %s err %d\n",
+ __func__, "queue", out->name, status);
+ list_add(&req->list, pool);
+ break;
+ }
+ port->read_started++;
+
+ /* abort immediately after disconnect */
+ if (!port->port_usb)
+ break;
+ }
+ return port->read_started;
+}
+
+/*
+ * RX work takes data out of the RX queue and hands it up to the TTY
+ * layer until it refuses to take any more data (or is throttled back).
+ * Then it issues reads for any further data.
+ *
+ * If the RX queue becomes full enough that no usb_request is queued,
+ * the OUT endpoint may begin NAKing as soon as its FIFO fills up.
+ * So QUEUE_SIZE packets plus however many the FIFO holds (usually two)
+ * can be buffered before the TTY layer's buffers (currently 64 KB).
+ */
+static void gs_rx_push(struct work_struct *work)
+{
+ struct delayed_work *w = to_delayed_work(work);
+ struct gs_port *port = container_of(w, struct gs_port, push);
+ struct tty_struct *tty;
+ struct list_head *queue = &port->read_queue;
+ bool disconnect = false;
+ bool do_push = false;
+
+ /* hand any queued data to the tty */
+ spin_lock_irq(&port->port_lock);
+ tty = port->port.tty;
+ while (!list_empty(queue)) {
+ struct usb_request *req;
+
+ req = list_first_entry(queue, struct usb_request, list);
+
+ /* leave data queued if tty was rx throttled */
+ if (tty && tty_throttled(tty))
+ break;
+
+ switch (req->status) {
+ case -ESHUTDOWN:
+ disconnect = true;
+ pr_vdebug("ttyGS%d: shutdown\n", port->port_num);
+ break;
+
+ default:
+ /* presumably a transient fault */
+ pr_warn("ttyGS%d: unexpected RX status %d\n",
+ port->port_num, req->status);
+ fallthrough;
+ case 0:
+ /* normal completion */
+ break;
+ }
+
+ /* push data to (open) tty */
+ if (req->actual && tty) {
+ char *packet = req->buf;
+ unsigned size = req->actual;
+ unsigned n;
+ int count;
+
+ /* we may have pushed part of this packet already... */
+ n = port->n_read;
+ if (n) {
+ packet += n;
+ size -= n;
+ }
+
+ count = tty_insert_flip_string(&port->port, packet,
+ size);
+ if (count)
+ do_push = true;
+ if (count != size) {
+ /* stop pushing; TTY layer can't handle more */
+ port->n_read += count;
+ pr_vdebug("ttyGS%d: rx block %d/%d\n",
+ port->port_num, count, req->actual);
+ break;
+ }
+ port->n_read = 0;
+ }
+
+ list_move(&req->list, &port->read_pool);
+ port->read_started--;
+ }
+
+ /* Push from tty to ldisc; this is handled by a workqueue,
+ * so we won't get callbacks and can hold port_lock
+ */
+ if (do_push)
+ tty_flip_buffer_push(&port->port);
+
+
+ /* We want our data queue to become empty ASAP, keeping data
+ * in the tty and ldisc (not here). If we couldn't push any
+ * this time around, RX may be starved, so wait until next jiffy.
+ *
+ * We may leave non-empty queue only when there is a tty, and
+ * either it is throttled or there is no more room in flip buffer.
+ */
+ if (!list_empty(queue) && !tty_throttled(tty))
+ schedule_delayed_work(&port->push, 1);
+
+ /* If we're still connected, refill the USB RX queue. */
+ if (!disconnect && port->port_usb)
+ gs_start_rx(port);
+
+ spin_unlock_irq(&port->port_lock);
+}
+
+static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
+{
+ struct gs_port *port = ep->driver_data;
+
+ /* Queue all received data until the tty layer is ready for it. */
+ spin_lock(&port->port_lock);
+ list_add_tail(&req->list, &port->read_queue);
+ schedule_delayed_work(&port->push, 0);
+ spin_unlock(&port->port_lock);
+}
+
+static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
+{
+ struct gs_port *port = ep->driver_data;
+
+ spin_lock(&port->port_lock);
+ list_add(&req->list, &port->write_pool);
+ port->write_started--;
+
+ switch (req->status) {
+ default:
+ /* presumably a transient fault */
+ pr_warn("%s: unexpected %s status %d\n",
+ __func__, ep->name, req->status);
+ fallthrough;
+ case 0:
+ /* normal completion */
+ gs_start_tx(port);
+ break;
+
+ case -ESHUTDOWN:
+ /* disconnect */
+ pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
+ break;
+ }
+
+ spin_unlock(&port->port_lock);
+}
+
+static void gs_free_requests(struct usb_ep *ep, struct list_head *head,
+ int *allocated)
+{
+ struct usb_request *req;
+
+ while (!list_empty(head)) {
+ req = list_entry(head->next, struct usb_request, list);
+ list_del(&req->list);
+ gs_free_req(ep, req);
+ if (allocated)
+ (*allocated)--;
+ }
+}
+
+static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
+ void (*fn)(struct usb_ep *, struct usb_request *),
+ int *allocated)
+{
+ int i;
+ struct usb_request *req;
+ int n = allocated ? QUEUE_SIZE - *allocated : QUEUE_SIZE;
+
+ /* Pre-allocate up to QUEUE_SIZE transfers, but if we can't
+ * do quite that many this time, don't fail ... we just won't
+ * be as speedy as we might otherwise be.
+ */
+ for (i = 0; i < n; i++) {
+ req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
+ if (!req)
+ return list_empty(head) ? -ENOMEM : 0;
+ req->complete = fn;
+ list_add_tail(&req->list, head);
+ if (allocated)
+ (*allocated)++;
+ }
+ return 0;
+}
+
+/**
+ * gs_start_io - start USB I/O streams
+ * @port: port to use
+ * Context: holding port_lock; port_tty and port_usb are non-null
+ *
+ * We only start I/O when something is connected to both sides of
+ * this port. If nothing is listening on the host side, we may
+ * be pointlessly filling up our TX buffers and FIFO.
+ */
+static int gs_start_io(struct gs_port *port)
+{
+ struct list_head *head = &port->read_pool;
+ struct usb_ep *ep = port->port_usb->out;
+ int status;
+ unsigned started;
+
+ /* Allocate RX and TX I/O buffers. We can't easily do this much
+ * earlier (with GFP_KERNEL) because the requests are coupled to
+ * endpoints, as are the packet sizes we'll be using. Different
+ * configurations may use different endpoints with a given port;
+ * and high speed vs full speed changes packet sizes too.
+ */
+ status = gs_alloc_requests(ep, head, gs_read_complete,
+ &port->read_allocated);
+ if (status)
+ return status;
+
+ status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
+ gs_write_complete, &port->write_allocated);
+ if (status) {
+ gs_free_requests(ep, head, &port->read_allocated);
+ return status;
+ }
+
+ /* queue read requests */
+ port->n_read = 0;
+ started = gs_start_rx(port);
+
+ if (started) {
+ gs_start_tx(port);
+ /* Unblock any pending writes into our circular buffer, in case
+ * we didn't in gs_start_tx() */
+ tty_wakeup(port->port.tty);
+ } else {
+ gs_free_requests(ep, head, &port->read_allocated);
+ gs_free_requests(port->port_usb->in, &port->write_pool,
+ &port->write_allocated);
+ status = -EIO;
+ }
+
+ return status;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* TTY Driver */
+
+/*
+ * gs_open sets up the link between a gs_port and its associated TTY.
+ * That link is broken *only* by TTY close(), and all driver methods
+ * know that.
+ */
+static int gs_open(struct tty_struct *tty, struct file *file)
+{
+ int port_num = tty->index;
+ struct gs_port *port;
+ int status = 0;
+
+ mutex_lock(&ports[port_num].lock);
+ port = ports[port_num].port;
+ if (!port) {
+ status = -ENODEV;
+ goto out;
+ }
+
+ spin_lock_irq(&port->port_lock);
+
+ /* allocate circular buffer on first open */
+ if (!kfifo_initialized(&port->port_write_buf)) {
+
+ spin_unlock_irq(&port->port_lock);
+
+ /*
+ * portmaster's mutex still protects from simultaneous open(),
+ * and close() can't happen, yet.
+ */
+
+ status = kfifo_alloc(&port->port_write_buf,
+ WRITE_BUF_SIZE, GFP_KERNEL);
+ if (status) {
+ pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
+ port_num, tty, file);
+ goto out;
+ }
+
+ spin_lock_irq(&port->port_lock);
+ }
+
+ /* already open? Great. */
+ if (port->port.count++)
+ goto exit_unlock_port;
+
+ tty->driver_data = port;
+ port->port.tty = tty;
+
+ /* if connected, start the I/O stream */
+ if (port->port_usb) {
+ /* if port is suspended, wait resume to start I/0 stream */
+ if (!port->suspended) {
+ struct gserial *gser = port->port_usb;
+
+ pr_debug("gs_open: start ttyGS%d\n", port->port_num);
+ gs_start_io(port);
+
+ if (gser->connect)
+ gser->connect(gser);
+ } else {
+ pr_debug("delay start of ttyGS%d\n", port->port_num);
+ port->start_delayed = true;
+ }
+ }
+
+ pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
+
+exit_unlock_port:
+ spin_unlock_irq(&port->port_lock);
+out:
+ mutex_unlock(&ports[port_num].lock);
+ return status;
+}
+
+static int gs_close_flush_done(struct gs_port *p)
+{
+ int cond;
+
+ /* return true on disconnect or empty buffer or if raced with open() */
+ spin_lock_irq(&p->port_lock);
+ cond = p->port_usb == NULL || !kfifo_len(&p->port_write_buf) ||
+ p->port.count > 1;
+ spin_unlock_irq(&p->port_lock);
+
+ return cond;
+}
+
+static void gs_close(struct tty_struct *tty, struct file *file)
+{
+ struct gs_port *port = tty->driver_data;
+ struct gserial *gser;
+
+ spin_lock_irq(&port->port_lock);
+
+ if (port->port.count != 1) {
+raced_with_open:
+ if (port->port.count == 0)
+ WARN_ON(1);
+ else
+ --port->port.count;
+ goto exit;
+ }
+
+ pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
+
+ gser = port->port_usb;
+ if (gser && !port->suspended && gser->disconnect)
+ gser->disconnect(gser);
+
+ /* wait for circular write buffer to drain, disconnect, or at
+ * most GS_CLOSE_TIMEOUT seconds; then discard the rest
+ */
+ if (kfifo_len(&port->port_write_buf) > 0 && gser) {
+ spin_unlock_irq(&port->port_lock);
+ wait_event_interruptible_timeout(port->drain_wait,
+ gs_close_flush_done(port),
+ GS_CLOSE_TIMEOUT * HZ);
+ spin_lock_irq(&port->port_lock);
+
+ if (port->port.count != 1)
+ goto raced_with_open;
+
+ gser = port->port_usb;
+ }
+
+ /* Iff we're disconnected, there can be no I/O in flight so it's
+ * ok to free the circular buffer; else just scrub it. And don't
+ * let the push async work fire again until we're re-opened.
+ */
+ if (gser == NULL)
+ kfifo_free(&port->port_write_buf);
+ else
+ kfifo_reset(&port->port_write_buf);
+
+ port->start_delayed = false;
+ port->port.count = 0;
+ port->port.tty = NULL;
+
+ pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
+ port->port_num, tty, file);
+
+ wake_up(&port->close_wait);
+exit:
+ spin_unlock_irq(&port->port_lock);
+}
+
+static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count)
+{
+ struct gs_port *port = tty->driver_data;
+ unsigned long flags;
+
+ pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n",
+ port->port_num, tty, count);
+
+ spin_lock_irqsave(&port->port_lock, flags);
+ if (count)
+ count = kfifo_in(&port->port_write_buf, buf, count);
+ /* treat count == 0 as flush_chars() */
+ if (port->port_usb)
+ gs_start_tx(port);
+ spin_unlock_irqrestore(&port->port_lock, flags);
+
+ return count;
+}
+
+static int gs_put_char(struct tty_struct *tty, unsigned char ch)
+{
+ struct gs_port *port = tty->driver_data;
+ unsigned long flags;
+ int status;
+
+ pr_vdebug("gs_put_char: (%d,%p) char=0x%x, called from %ps\n",
+ port->port_num, tty, ch, __builtin_return_address(0));
+
+ spin_lock_irqsave(&port->port_lock, flags);
+ status = kfifo_put(&port->port_write_buf, ch);
+ spin_unlock_irqrestore(&port->port_lock, flags);
+
+ return status;
+}
+
+static void gs_flush_chars(struct tty_struct *tty)
+{
+ struct gs_port *port = tty->driver_data;
+ unsigned long flags;
+
+ pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);
+
+ spin_lock_irqsave(&port->port_lock, flags);
+ if (port->port_usb)
+ gs_start_tx(port);
+ spin_unlock_irqrestore(&port->port_lock, flags);
+}
+
+static unsigned int gs_write_room(struct tty_struct *tty)
+{
+ struct gs_port *port = tty->driver_data;
+ unsigned long flags;
+ unsigned int room = 0;
+
+ spin_lock_irqsave(&port->port_lock, flags);
+ if (port->port_usb)
+ room = kfifo_avail(&port->port_write_buf);
+ spin_unlock_irqrestore(&port->port_lock, flags);
+
+ pr_vdebug("gs_write_room: (%d,%p) room=%u\n",
+ port->port_num, tty, room);
+
+ return room;
+}
+
+static unsigned int gs_chars_in_buffer(struct tty_struct *tty)
+{
+ struct gs_port *port = tty->driver_data;
+ unsigned long flags;
+ unsigned int chars;
+
+ spin_lock_irqsave(&port->port_lock, flags);
+ chars = kfifo_len(&port->port_write_buf);
+ spin_unlock_irqrestore(&port->port_lock, flags);
+
+ pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%u\n",
+ port->port_num, tty, chars);
+
+ return chars;
+}
+
+/* undo side effects of setting TTY_THROTTLED */
+static void gs_unthrottle(struct tty_struct *tty)
+{
+ struct gs_port *port = tty->driver_data;
+ unsigned long flags;
+
+ spin_lock_irqsave(&port->port_lock, flags);
+ if (port->port_usb) {
+ /* Kickstart read queue processing. We don't do xon/xoff,
+ * rts/cts, or other handshaking with the host, but if the
+ * read queue backs up enough we'll be NAKing OUT packets.
+ */
+ pr_vdebug("ttyGS%d: unthrottle\n", port->port_num);
+ schedule_delayed_work(&port->push, 0);
+ }
+ spin_unlock_irqrestore(&port->port_lock, flags);
+}
+
+static int gs_break_ctl(struct tty_struct *tty, int duration)
+{
+ struct gs_port *port = tty->driver_data;
+ int status = 0;
+ struct gserial *gser;
+
+ pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n",
+ port->port_num, duration);
+
+ spin_lock_irq(&port->port_lock);
+ gser = port->port_usb;
+ if (gser && gser->send_break)
+ status = gser->send_break(gser, duration);
+ spin_unlock_irq(&port->port_lock);
+
+ return status;
+}
+
+static const struct tty_operations gs_tty_ops = {
+ .open = gs_open,
+ .close = gs_close,
+ .write = gs_write,
+ .put_char = gs_put_char,
+ .flush_chars = gs_flush_chars,
+ .write_room = gs_write_room,
+ .chars_in_buffer = gs_chars_in_buffer,
+ .unthrottle = gs_unthrottle,
+ .break_ctl = gs_break_ctl,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static struct tty_driver *gs_tty_driver;
+
+#ifdef CONFIG_U_SERIAL_CONSOLE
+
+static void gs_console_complete_out(struct usb_ep *ep, struct usb_request *req)
+{
+ struct gs_console *cons = req->context;
+
+ switch (req->status) {
+ default:
+ pr_warn("%s: unexpected %s status %d\n",
+ __func__, ep->name, req->status);
+ fallthrough;
+ case 0:
+ /* normal completion */
+ spin_lock(&cons->lock);
+ req->length = 0;
+ schedule_work(&cons->work);
+ spin_unlock(&cons->lock);
+ break;
+ case -ECONNRESET:
+ case -ESHUTDOWN:
+ /* disconnect */
+ pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
+ break;
+ }
+}
+
+static void __gs_console_push(struct gs_console *cons)
+{
+ struct usb_request *req = cons->req;
+ struct usb_ep *ep;
+ size_t size;
+
+ if (!req)
+ return; /* disconnected */
+
+ if (req->length)
+ return; /* busy */
+
+ ep = cons->console.data;
+ size = kfifo_out(&cons->buf, req->buf, ep->maxpacket);
+ if (!size)
+ return;
+
+ if (cons->missed && ep->maxpacket >= 64) {
+ char buf[64];
+ size_t len;
+
+ len = sprintf(buf, "\n[missed %zu bytes]\n", cons->missed);
+ kfifo_in(&cons->buf, buf, len);
+ cons->missed = 0;
+ }
+
+ req->length = size;
+
+ 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 = strtobool(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;
+ spin_unlock_irqrestore(&port->port_lock, flags);
+}
+EXPORT_SYMBOL_GPL(gserial_suspend);
+
+void gserial_resume(struct gserial *gser)
+{
+ struct gs_port *port;
+ unsigned long flags;
+
+ spin_lock_irqsave(&serial_port_lock, flags);
+ port = gser->ioport;
+
+ if (!port) {
+ spin_unlock_irqrestore(&serial_port_lock, flags);
+ return;
+ }
+
+ spin_lock(&port->port_lock);
+ spin_unlock(&serial_port_lock);
+ port->suspended = false;
+ if (!port->start_delayed) {
+ spin_unlock_irqrestore(&port->port_lock, flags);
+ return;
+ }
+
+ pr_debug("delayed start ttyGS%d\n", port->port_num);
+ gs_start_io(port);
+ if (gser->connect)
+ gser->connect(gser);
+ port->start_delayed = false;
+ spin_unlock_irqrestore(&port->port_lock, flags);
+}
+EXPORT_SYMBOL_GPL(gserial_resume);
+
+static int __init userial_init(void)
+{
+ struct tty_driver *driver;
+ unsigned i;
+ int status;
+
+ driver = tty_alloc_driver(MAX_U_SERIAL_PORTS, TTY_DRIVER_REAL_RAW |
+ TTY_DRIVER_DYNAMIC_DEV);
+ if (IS_ERR(driver))
+ return PTR_ERR(driver);
+
+ driver->driver_name = "g_serial";
+ driver->name = "ttyGS";
+ /* uses dynamically assigned dev_t values */
+
+ driver->type = TTY_DRIVER_TYPE_SERIAL;
+ driver->subtype = SERIAL_TYPE_NORMAL;
+ driver->init_termios = tty_std_termios;
+
+ /* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on
+ * MS-Windows. Otherwise, most of these flags shouldn't affect
+ * anything unless we were to actually hook up to a serial line.
+ */
+ driver->init_termios.c_cflag =
+ B9600 | CS8 | CREAD | HUPCL | CLOCAL;
+ driver->init_termios.c_ispeed = 9600;
+ driver->init_termios.c_ospeed = 9600;
+
+ tty_set_operations(driver, &gs_tty_ops);
+ for (i = 0; i < MAX_U_SERIAL_PORTS; i++)
+ mutex_init(&ports[i].lock);
+
+ /* export the driver ... */
+ status = tty_register_driver(driver);
+ if (status) {
+ pr_err("%s: cannot register, err %d\n",
+ __func__, status);
+ goto fail;
+ }
+
+ gs_tty_driver = driver;
+
+ pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
+ MAX_U_SERIAL_PORTS,
+ (MAX_U_SERIAL_PORTS == 1) ? "" : "s");
+
+ return status;
+fail:
+ tty_driver_kref_put(driver);
+ return status;
+}
+module_init(userial_init);
+
+static void __exit userial_cleanup(void)
+{
+ tty_unregister_driver(gs_tty_driver);
+ tty_driver_kref_put(gs_tty_driver);
+ gs_tty_driver = NULL;
+}
+module_exit(userial_cleanup);
+
+MODULE_LICENSE("GPL");