diff options
Diffstat (limited to 'drivers/usb/gadget/u_serial.c')
| -rw-r--r-- | drivers/usb/gadget/u_serial.c | 1243 |
1 files changed, 1243 insertions, 0 deletions
diff --git a/drivers/usb/gadget/u_serial.c b/drivers/usb/gadget/u_serial.c new file mode 100644 index 000000000000..88d4f5452c49 --- /dev/null +++ b/drivers/usb/gadget/u_serial.c @@ -0,0 +1,1243 @@ +/* + * 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); +} |
