--- /dev/null
+/*
+ * u_serial.c - utilities for USB gadget "serial port"/TTY support
+ *
+ * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
+ * Copyright (C) 2008 David Brownell
+ * Copyright (C) 2008 by Nokia Corporation
+ *
+ * This code also borrows from usbserial.c, which is
+ * Copyright (C) 1999 - 2002 Greg Kroah-Hartman (greg@kroah.com)
+ * Copyright (C) 2000 Peter Berger (pberger@brimson.com)
+ * Copyright (C) 2000 Al Borchers (alborchers@steinerpoint.com)
+ *
+ * This software is distributed under the terms of the GNU General
+ * Public License ("GPL") as published by the Free Software Foundation,
+ * either version 2 of that License or (at your option) any later version.
+ */
+
+/* #define VERBOSE_DEBUG */
+
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+#include "u_serial.h"
+
+
+/*
+ * This component encapsulates the TTY layer glue needed to provide basic
+ * "serial port" functionality through the USB gadget stack. Each such
+ * port is exposed through a /dev/ttyGS* node.
+ *
+ * After initialization (gserial_setup), these TTY port devices stay
+ * available until they are removed (gserial_cleanup). Each one may be
+ * connected to a USB function (gserial_connect), or disconnected (with
+ * gserial_disconnect) when the USB host issues a config change event.
+ * Data can only flow when the port is connected to the host.
+ *
+ * A given TTY port can be made available in multiple configurations.
+ * For example, each one might expose a ttyGS0 node which provides a
+ * login application. In one case that might use CDC ACM interface 0,
+ * while another configuration might use interface 3 for that. The
+ * work to handle that (including descriptor management) is not part
+ * of this component.
+ *
+ * Configurations may expose more than one TTY port. For example, if
+ * ttyGS0 provides login service, then ttyGS1 might provide dialer access
+ * for a telephone or fax link. And ttyGS2 might be something that just
+ * needs a simple byte stream interface for some messaging protocol that
+ * is managed in userspace ... OBEX, PTP, and MTP have been mentioned.
+ */
+
+/*
+ * 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}().
+ * 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 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 available in 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.
+ */
+static 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.
+ */
+static 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);
+
+#ifdef VERBOSE_DEBUG
+ pr_debug("%s: %s, len=%d, 0x%02x 0x%02x 0x%02x ...\n",
+ __func__, in->name, len, *((u8 *)req->buf),
+ *((u8 *)req->buf+1), *((u8 *)req->buf+2));
+#endif
+
+ /* 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;
+}
+
+static void gs_rx_push(unsigned long _port)
+{
+ struct gs_port *port = (void *)_port;
+ struct tty_struct *tty = port->port_tty;
+
+ /* With low_latency, tty_flip_buffer_push() doesn't put its
+ * real work through a workqueue, so the ldisc has a better
+ * chance to keep up with peak USB data rates.
+ */
+ if (tty) {
+ tty_flip_buffer_push(tty);
+ wake_up_interruptible(&tty->read_wait);
+ }
+}
+
+/*
+ * gs_recv_packet
+ *
+ * Called for each USB packet received. Reads the packet
+ * header and stuffs the data in the appropriate tty buffer.
+ * Returns 0 if successful, or a negative error number.
+ *
+ * Called during USB completion routine, on interrupt time.
+ * With port_lock.
+ */
+static int gs_recv_packet(struct gs_port *port, char *packet, unsigned size)
+{
+ unsigned len;
+ struct tty_struct *tty;
+
+ /* I/O completions can continue for a while after close(), until the
+ * request queue empties. Just discard any data we receive, until
+ * something reopens this TTY ... as if there were no HW flow control.
+ */
+ tty = port->port_tty;
+ if (tty == NULL) {
+ pr_vdebug("%s: ttyGS%d, after close\n",
+ __func__, port->port_num);
+ return -EIO;
+ }
+
+ len = tty_insert_flip_string(tty, packet, size);
+ if (len > 0)
+ tasklet_schedule(&port->push);
+ if (len < size)
+ pr_debug("%s: ttyGS%d, drop %d bytes\n",
+ __func__, port->port_num, size - len);
+ return 0;
+}
+
+/*
+ * 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 or throttled */
+ tty = port->port_tty;
+ if (!tty || test_bit(TTY_THROTTLED, &tty->flags))
+ 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;
+}
+
+static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
+{
+ int status;
+ struct gs_port *port = ep->driver_data;
+
+ spin_lock(&port->port_lock);
+ list_add(&req->list, &port->read_pool);
+
+ switch (req->status) {
+ case 0:
+ /* normal completion */
+ status = gs_recv_packet(port, req->buf, req->actual);
+ if (status && status != -EIO)
+ pr_debug("%s: %s %s err %d\n",
+ __func__, "recv", ep->name, status);
+ gs_start_rx(port);
+ break;
+
+ case -ESHUTDOWN:
+ /* disconnect */
+ pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
+ break;
+
+ default:
+ /* presumably a transient fault */
+ pr_warning("%s: unexpected %s status %d\n",
+ __func__, ep->name, req->status);
+ gs_start_rx(port);
+ break;
+ }
+ 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 */
+ 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);
+ }
+
+ return started ? 0 : status;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* TTY Driver */
+
+/*
+ * gs_open sets up the link between a gs_port and its associated TTY.
+ * That link is broken *only* by TTY close(), and all driver methods
+ * know that.
+ */
+static int gs_open(struct tty_struct *tty, struct file *file)
+{
+ int port_num = tty->index;
+ struct gs_port *port;
+ int status;
+
+ if (port_num < 0 || port_num >= n_ports)
+ return -ENXIO;
+
+ do {
+ mutex_lock(&ports[port_num].lock);
+ port = ports[port_num].port;
+ if (!port)
+ status = -ENODEV;
+ else {
+ spin_lock_irq(&port->port_lock);
+
+ /* already open? Great. */
+ if (port->open_count) {
+ status = 0;
+ port->open_count++;
+
+ /* currently opening/closing? wait ... */
+ } else if (port->openclose) {
+ status = -EBUSY;
+
+ /* ... else we do the work */
+ } else {
+ status = -EAGAIN;
+ port->openclose = true;
+ }
+ spin_unlock_irq(&port->port_lock);
+ }
+ mutex_unlock(&ports[port_num].lock);
+
+ switch (status) {
+ default:
+ /* fully handled */
+ return status;
+ case -EAGAIN:
+ /* must do the work */
+ break;
+ case -EBUSY:
+ /* wait for EAGAIN task to finish */
+ msleep(1);
+ /* REVISIT could have a waitchannel here, if
+ * concurrent open performance is important
+ */
+ break;
+ }
+ } while (status != -EAGAIN);
+
+ /* Do the "real open" */
+ spin_lock_irq(&port->port_lock);
+
+ /* allocate circular buffer on first open */
+ if (port->port_write_buf.buf_buf == NULL) {
+
+ spin_unlock_irq(&port->port_lock);
+ status = gs_buf_alloc(&port->port_write_buf, WRITE_BUF_SIZE);
+ spin_lock_irq(&port->port_lock);
+
+ if (status) {
+ pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
+ port->port_num, tty, file);
+ port->openclose = false;
+ goto exit_unlock_port;
+ }
+ }
+
+ /* REVISIT if REMOVED (ports[].port NULL), abort the open
+ * to let rmmod work faster (but this way isn't wrong).
+ */
+
+ /* REVISIT maybe wait for "carrier detect" */
+
+ tty->driver_data = port;
+ port->port_tty = tty;
+
+ port->open_count = 1;
+ port->openclose = false;
+
+ /* low_latency means ldiscs work in tasklet context, without
+ * needing a workqueue schedule ... easier to keep up.
+ */
+ tty->low_latency = 1;
+
+ /* if connected, start the I/O stream */
+ if (port->port_usb) {
+ pr_debug("gs_open: start ttyGS%d\n", port->port_num);
+ gs_start_io(port);
+
+ /* REVISIT for ACM, issue "network connected" event */
+ }
+
+ 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;
+
+ 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;
+
+ if (port->port_usb)
+ /* REVISIT for ACM, issue "network disconnected" event */;
+
+ /* 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
+ && port->port_usb) {
+ 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);
+ }
+
+ /* 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 (port->port_usb == NULL)
+ gs_buf_free(&port->port_write_buf);
+ else
+ gs_buf_clear(&port->port_write_buf);
+
+ tasklet_kill(&port->push);
+
+ 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;
+ unsigned started = 0;
+
+ spin_lock_irqsave(&port->port_lock, flags);
+ if (port->port_usb)
+ started = gs_start_rx(port);
+ spin_unlock_irqrestore(&port->port_lock, flags);
+
+ pr_vdebug("gs_unthrottle: ttyGS%d, %d packets\n",
+ port->port_num, started);
+}
+
+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,
+};
+
+/*-------------------------------------------------------------------------*/
+
+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->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 = "ttyGS";
+ /* 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 = __constant_cpu_to_le32(9600);
+ coding.bCharFormat = 8;
+ coding.bParityType = USB_CDC_NO_PARITY;
+ coding.bDataBits = USB_CDC_1_STOP_BITS;
+
+ tty_set_operations(gs_tty_driver, &gs_tty_ops);
+
+ /* make devices be openable */
+ for (i = 0; i < count; i++) {
+ mutex_init(&ports[i].lock);
+ status = gs_port_alloc(i, &coding);
+ if (status) {
+ count = i;
+ goto fail;
+ }
+ }
+ n_ports = count;
+
+ /* export the driver ... */
+ status = tty_register_driver(gs_tty_driver);
+ if (status) {
+ put_tty_driver(gs_tty_driver);
+ pr_err("%s: cannot register, err %d\n",
+ __func__, status);
+ goto fail;
+ }
+
+ /* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
+ for (i = 0; i < count; i++) {
+ struct device *tty_dev;
+
+ tty_dev = tty_register_device(gs_tty_driver, i, &g->dev);
+ if (IS_ERR(tty_dev))
+ pr_warning("%s: no classdev for port %d, err %ld\n",
+ __func__, i, PTR_ERR(tty_dev));
+ }
+
+ pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
+ count, (count == 1) ? "" : "s");
+
+ return status;
+fail:
+ while (count--)
+ kfree(ports[count].port);
+ put_tty_driver(gs_tty_driver);
+ gs_tty_driver = NULL;
+ return status;
+}
+
+static int gs_closed(struct gs_port *port)
+{
+ int cond;
+
+ spin_lock_irq(&port->port_lock);
+ cond = (port->open_count == 0) && !port->openclose;
+ spin_unlock_irq(&port->port_lock);
+ return cond;
+}
+
+/**
+ * gserial_cleanup - remove TTY-over-USB driver and devices
+ * Context: may sleep
+ *
+ * This is called to free all resources allocated by @gserial_setup().
+ * Accordingly, it may need to wait until some open /dev/ files have
+ * closed.
+ *
+ * The caller must have issued @gserial_disconnect() for any ports
+ * that had previously been connected, so that there is never any
+ * I/O pending when it's called.
+ */
+void gserial_cleanup(void)
+{
+ unsigned i;
+ struct gs_port *port;
+
+ /* 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);
+
+ /* 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. */
+
+ /* REVISIT for ACM, issue "network connection" status notification:
+ * connected if open_count, else disconnected.
+ */
+
+ /* if it's already open, start I/O */
+ if (port->open_count) {
+ pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
+ gs_start_io(port);
+ }
+
+ 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->in, &port->write_pool);
+ spin_unlock_irqrestore(&port->port_lock, flags);
+}
projects / users / willy / pagecache.git / commitdiff