| /* |
| * 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/sched.h> |
| #include <linux/interrupt.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 "u_serial.h" |
| |
| |
| /* |
| * This component encapsulates the TTY layer glue needed to provide basic |
| * "serial port" functionality through the USB gadget stack. Each such |
| * port is exposed through a /dev/ttyGS* node. |
| * |
| * After initialization (gserial_setup), these TTY port devices stay |
| * available until they are removed (gserial_cleanup). Each one may be |
| * connected to a USB function (gserial_connect), or disconnected (with |
| * gserial_disconnect) when the USB host issues a config change event. |
| * Data can only flow when the port is connected to the host. |
| * |
| * A given TTY port can be made available in multiple configurations. |
| * For example, each one might expose a ttyGS0 node which provides a |
| * login application. In one case that might use CDC ACM interface 0, |
| * while another configuration might use interface 3 for that. The |
| * work to handle that (including descriptor management) is not part |
| * of this component. |
| * |
| * Configurations may expose more than one TTY port. For example, if |
| * ttyGS0 provides login service, then ttyGS1 might provide dialer access |
| * for a telephone or fax link. And ttyGS2 might be something that just |
| * needs a simple byte stream interface for some messaging protocol that |
| * is managed in userspace ... OBEX, PTP, and MTP have been mentioned. |
| */ |
| |
| #define PREFIX "ttyGS" |
| |
| /* |
| * gserial is the lifecycle interface, used by USB functions |
| * gs_port is the I/O nexus, used by the tty driver |
| * tty_struct links to the tty/filesystem framework |
| * |
| * gserial <---> gs_port ... links will be null when the USB link is |
| * inactive; managed by gserial_{connect,disconnect}(). each gserial |
| * instance can wrap its own USB control protocol. |
| * gserial->ioport == usb_ep->driver_data ... gs_port |
| * gs_port->port_usb ... gserial |
| * |
| * gs_port <---> tty_struct ... links will be null when the TTY file |
| * isn't opened; managed by gs_open()/gs_close() |
| * gserial->port_tty ... tty_struct |
| * tty_struct->driver_data ... gserial |
| */ |
| |
| /* RX and TX queues can buffer QUEUE_SIZE packets before they hit the |
| * next layer of buffering. For TX that's a circular buffer; for RX |
| * consider it a NOP. A third layer is provided by the TTY code. |
| */ |
| #define QUEUE_SIZE 16 |
| #define WRITE_BUF_SIZE 8192 /* TX only */ |
| |
| /* circular buffer */ |
| struct gs_buf { |
| unsigned buf_size; |
| char *buf_buf; |
| char *buf_get; |
| char *buf_put; |
| }; |
| |
| /* |
| * The port structure holds info for each port, one for each minor number |
| * (and thus for each /dev/ node). |
| */ |
| struct gs_port { |
| struct tty_port port; |
| spinlock_t port_lock; /* guard port_* access */ |
| |
| struct gserial *port_usb; |
| |
| bool openclose; /* open/close in progress */ |
| u8 port_num; |
| |
| struct list_head read_pool; |
| int read_started; |
| int read_allocated; |
| struct list_head read_queue; |
| unsigned n_read; |
| struct tasklet_struct push; |
| |
| struct list_head write_pool; |
| int write_started; |
| int write_allocated; |
| struct gs_buf port_write_buf; |
| wait_queue_head_t drain_wait; /* wait while writes drain */ |
| |
| /* REVISIT this state ... */ |
| struct usb_cdc_line_coding port_line_coding; /* 8-N-1 etc */ |
| }; |
| |
| /* increase N_PORTS if you need more */ |
| #define N_PORTS 4 |
| static struct portmaster { |
| struct mutex lock; /* protect open/close */ |
| struct gs_port *port; |
| } ports[N_PORTS]; |
| static unsigned n_ports; |
| |
| #define GS_CLOSE_TIMEOUT 15 /* seconds */ |
| |
| |
| |
| #ifdef VERBOSE_DEBUG |
| #define pr_vdebug(fmt, arg...) \ |
| pr_debug(fmt, ##arg) |
| #else |
| #define pr_vdebug(fmt, arg...) \ |
| ({ if (0) pr_debug(fmt, ##arg); }) |
| #endif |
| |
| /*-------------------------------------------------------------------------*/ |
| |
| /* Circular Buffer */ |
| |
| /* |
| * gs_buf_alloc |
| * |
| * Allocate a circular buffer and all associated memory. |
| */ |
| static int gs_buf_alloc(struct gs_buf *gb, unsigned size) |
| { |
| gb->buf_buf = kmalloc(size, GFP_KERNEL); |
| if (gb->buf_buf == NULL) |
| return -ENOMEM; |
| |
| gb->buf_size = size; |
| gb->buf_put = gb->buf_buf; |
| gb->buf_get = gb->buf_buf; |
| |
| return 0; |
| } |
| |
| /* |
| * gs_buf_free |
| * |
| * Free the buffer and all associated memory. |
| */ |
| static void gs_buf_free(struct gs_buf *gb) |
| { |
| kfree(gb->buf_buf); |
| gb->buf_buf = NULL; |
| } |
| |
| /* |
| * gs_buf_clear |
| * |
| * Clear out all data in the circular buffer. |
| */ |
| static void gs_buf_clear(struct gs_buf *gb) |
| { |
| gb->buf_get = gb->buf_put; |
| /* equivalent to a get of all data available */ |
| } |
| |
| /* |
| * gs_buf_data_avail |
| * |
| * Return the number of bytes of data written into the circular |
| * buffer. |
| */ |
| static unsigned gs_buf_data_avail(struct gs_buf *gb) |
| { |
| return (gb->buf_size + gb->buf_put - gb->buf_get) % gb->buf_size; |
| } |
| |
| /* |
| * gs_buf_space_avail |
| * |
| * Return the number of bytes of space available in the circular |
| * buffer. |
| */ |
| static unsigned gs_buf_space_avail(struct gs_buf *gb) |
| { |
| return (gb->buf_size + gb->buf_get - gb->buf_put - 1) % gb->buf_size; |
| } |
| |
| /* |
| * gs_buf_put |
| * |
| * Copy data data from a user buffer and put it into the circular buffer. |
| * Restrict to the amount of space available. |
| * |
| * Return the number of bytes copied. |
| */ |
| static unsigned |
| gs_buf_put(struct gs_buf *gb, const char *buf, unsigned count) |
| { |
| unsigned len; |
| |
| len = gs_buf_space_avail(gb); |
| if (count > len) |
| count = len; |
| |
| if (count == 0) |
| return 0; |
| |
| len = gb->buf_buf + gb->buf_size - gb->buf_put; |
| if (count > len) { |
| memcpy(gb->buf_put, buf, len); |
| memcpy(gb->buf_buf, buf+len, count - len); |
| gb->buf_put = gb->buf_buf + count - len; |
| } else { |
| memcpy(gb->buf_put, buf, count); |
| if (count < len) |
| gb->buf_put += count; |
| else /* count == len */ |
| gb->buf_put = gb->buf_buf; |
| } |
| |
| return count; |
| } |
| |
| /* |
| * gs_buf_get |
| * |
| * Get data from the circular buffer and copy to the given buffer. |
| * Restrict to the amount of data available. |
| * |
| * Return the number of bytes copied. |
| */ |
| static unsigned |
| gs_buf_get(struct gs_buf *gb, char *buf, unsigned count) |
| { |
| unsigned len; |
| |
| len = gs_buf_data_avail(gb); |
| if (count > len) |
| count = len; |
| |
| if (count == 0) |
| return 0; |
| |
| len = gb->buf_buf + gb->buf_size - gb->buf_get; |
| if (count > len) { |
| memcpy(buf, gb->buf_get, len); |
| memcpy(buf+len, gb->buf_buf, count - len); |
| gb->buf_get = gb->buf_buf + count - len; |
| } else { |
| memcpy(buf, gb->buf_get, count); |
| if (count < len) |
| gb->buf_get += count; |
| else /* count == len */ |
| gb->buf_get = gb->buf_buf; |
| } |
| |
| return count; |
| } |
| |
| /*-------------------------------------------------------------------------*/ |
| |
| /* I/O glue between TTY (upper) and USB function (lower) driver layers */ |
| |
| /* |
| * gs_alloc_req |
| * |
| * Allocate a usb_request and its buffer. Returns a pointer to the |
| * usb_request or NULL if there is an error. |
| */ |
| struct usb_request * |
| gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags) |
| { |
| struct usb_request *req; |
| |
| req = usb_ep_alloc_request(ep, kmalloc_flags); |
| |
| if (req != NULL) { |
| req->length = len; |
| req->buf = kmalloc(len, kmalloc_flags); |
| if (req->buf == NULL) { |
| usb_ep_free_request(ep, req); |
| return NULL; |
| } |
| } |
| |
| return req; |
| } |
| |
| /* |
| * gs_free_req |
| * |
| * Free a usb_request and its buffer. |
| */ |
| void gs_free_req(struct usb_ep *ep, struct usb_request *req) |
| { |
| kfree(req->buf); |
| usb_ep_free_request(ep, req); |
| } |
| |
| /* |
| * gs_send_packet |
| * |
| * If there is data to send, a packet is built in the given |
| * buffer and the size is returned. If there is no data to |
| * send, 0 is returned. |
| * |
| * Called with port_lock held. |
| */ |
| static unsigned |
| gs_send_packet(struct gs_port *port, char *packet, unsigned size) |
| { |
| unsigned len; |
| |
| len = gs_buf_data_avail(&port->port_write_buf); |
| if (len < size) |
| size = len; |
| if (size != 0) |
| size = gs_buf_get(&port->port_write_buf, packet, size); |
| return size; |
| } |
| |
| /* |
| * gs_start_tx |
| * |
| * This function finds available write requests, calls |
| * gs_send_packet to fill these packets with data, and |
| * continues until either there are no more write requests |
| * available or no more data to send. This function is |
| * run whenever data arrives or write requests are available. |
| * |
| * Context: caller owns port_lock; port_usb is non-null. |
| */ |
| static int gs_start_tx(struct gs_port *port) |
| /* |
| __releases(&port->port_lock) |
| __acquires(&port->port_lock) |
| */ |
| { |
| struct list_head *pool = &port->write_pool; |
| struct usb_ep *in = port->port_usb->in; |
| int status = 0; |
| bool do_tty_wake = false; |
| |
| while (!list_empty(pool)) { |
| struct usb_request *req; |
| int len; |
| |
| 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 = (gs_buf_data_avail(&port->port_write_buf) == 0); |
| |
| pr_vdebug(PREFIX "%d: tx len=%d, 0x%02x 0x%02x 0x%02x ...\n", |
| port->port_num, len, *((u8 *)req->buf), |
| *((u8 *)req->buf+1), *((u8 *)req->buf+2)); |
| |
| /* Drop lock while we call out of driver; completions |
| * could be issued while we do so. Disconnection may |
| * happen too; maybe immediately before we queue this! |
| * |
| * NOTE that we may keep sending data for a while after |
| * the TTY closed (dev->ioport->port_tty is NULL). |
| */ |
| spin_unlock(&port->port_lock); |
| status = usb_ep_queue(in, req, GFP_ATOMIC); |
| spin_lock(&port->port_lock); |
| |
| if (status) { |
| pr_debug("%s: %s %s err %d\n", |
| __func__, "queue", in->name, status); |
| list_add(&req->list, pool); |
| break; |
| } |
| |
| 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 tasklet takes data out of the RX queue and hands it up to the TTY |
| * layer until it refuses to take any more data (or is throttled back). |
| * Then it issues reads for any further data. |
| * |
| * If the RX queue becomes full enough that no usb_request is queued, |
| * the OUT endpoint may begin NAKing as soon as its FIFO fills up. |
| * So QUEUE_SIZE packets plus however many the FIFO holds (usually two) |
| * can be buffered before the TTY layer's buffers (currently 64 KB). |
| */ |
| static void gs_rx_push(unsigned long _port) |
| { |
| struct gs_port *port = (void *)_port; |
| struct tty_struct *tty; |
| struct list_head *queue = &port->read_queue; |
| bool disconnect = false; |
| bool do_push = false; |
| |
| /* hand any queued data to the tty */ |
| spin_lock_irq(&port->port_lock); |
| tty = port->port.tty; |
| while (!list_empty(queue)) { |
| struct usb_request *req; |
| |
| req = list_first_entry(queue, struct usb_request, list); |
| |
| /* discard data if tty was closed */ |
| if (!tty) |
| goto recycle; |
| |
| /* leave data queued if tty was rx throttled */ |
| if (test_bit(TTY_THROTTLED, &tty->flags)) |
| break; |
| |
| switch (req->status) { |
| case -ESHUTDOWN: |
| disconnect = true; |
| pr_vdebug(PREFIX "%d: shutdown\n", port->port_num); |
| break; |
| |
| default: |
| /* presumably a transient fault */ |
| pr_warning(PREFIX "%d: unexpected RX status %d\n", |
| port->port_num, req->status); |
| /* FALLTHROUGH */ |
| case 0: |
| /* normal completion */ |
| break; |
| } |
| |
| /* push data to (open) tty */ |
| if (req->actual) { |
| char *packet = req->buf; |
| unsigned size = req->actual; |
| unsigned n; |
| int count; |
| |
| /* we may have pushed part of this packet already... */ |
| n = port->n_read; |
| if (n) { |
| packet += n; |
| size -= n; |
| } |
| |
| count = tty_insert_flip_string(tty, packet, size); |
| if (count) |
| do_push = true; |
| if (count != size) { |
| /* stop pushing; TTY layer can't handle more */ |
| port->n_read += count; |
| pr_vdebug(PREFIX "%d: rx block %d/%d\n", |
| port->port_num, |
| count, req->actual); |
| break; |
| } |
| port->n_read = 0; |
| } |
| recycle: |
| list_move(&req->list, &port->read_pool); |
| port->read_started--; |
| } |
| |
| /* Push from tty to ldisc; without low_latency set this is handled by |
| * a workqueue, so we won't get callbacks and can hold port_lock |
| */ |
| if (tty && do_push) |
| tty_flip_buffer_push(tty); |
| |
| |
| /* We want our data queue to become empty ASAP, keeping data |
| * in the tty and ldisc (not here). If we couldn't push any |
| * this time around, there may be trouble unless there's an |
| * implicit tty_unthrottle() call on its way... |
| * |
| * REVISIT we should probably add a timer to keep the tasklet |
| * from starving ... but it's not clear that case ever happens. |
| */ |
| if (!list_empty(queue) && tty) { |
| if (!test_bit(TTY_THROTTLED, &tty->flags)) { |
| if (do_push) |
| tasklet_schedule(&port->push); |
| else |
| pr_warning(PREFIX "%d: RX not scheduled?\n", |
| port->port_num); |
| } |
| } |
| |
| /* If we're still connected, refill the USB RX queue. */ |
| if (!disconnect && port->port_usb) |
| gs_start_rx(port); |
| |
| spin_unlock_irq(&port->port_lock); |
| } |
| |
| static void gs_read_complete(struct usb_ep *ep, struct usb_request *req) |
| { |
| struct gs_port *port = ep->driver_data; |
| |
| /* Queue all received data until the tty layer is ready for it. */ |
| spin_lock(&port->port_lock); |
| list_add_tail(&req->list, &port->read_queue); |
| tasklet_schedule(&port->push); |
| spin_unlock(&port->port_lock); |
| } |
| |
| static void gs_write_complete(struct usb_ep *ep, struct usb_request *req) |
| { |
| struct gs_port *port = ep->driver_data; |
| |
| spin_lock(&port->port_lock); |
| list_add(&req->list, &port->write_pool); |
| port->write_started--; |
| |
| 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, |
| 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 |
| * @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, |
| &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); |
| |
| /* unblock any pending writes into our circular buffer */ |
| if (started) { |
| 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; |
| |
| 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->port.count) { |
| status = 0; |
| port->port.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->port.count = 1; |
| port->openclose = false; |
| |
| /* if connected, start the I/O stream */ |
| if (port->port_usb) { |
| struct gserial *gser = port->port_usb; |
| |
| pr_debug("gs_open: start ttyGS%d\n", port->port_num); |
| gs_start_io(port); |
| |
| if (gser->connect) |
| gser->connect(gser); |
| } |
| |
| pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file); |
| |
| status = 0; |
| |
| exit_unlock_port: |
| spin_unlock_irq(&port->port_lock); |
| return status; |
| } |
| |
| static int gs_writes_finished(struct gs_port *p) |
| { |
| int cond; |
| |
| /* return true on disconnect or empty buffer */ |
| spin_lock_irq(&p->port_lock); |
| cond = (p->port_usb == NULL) || !gs_buf_data_avail(&p->port_write_buf); |
| spin_unlock_irq(&p->port_lock); |
| |
| return cond; |
| } |
| |
| static void gs_close(struct tty_struct *tty, struct file *file) |
| { |
| struct gs_port *port = tty->driver_data; |
| struct gserial *gser; |
| |
| spin_lock_irq(&port->port_lock); |
| |
| if (port->port.count != 1) { |
| 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); |
| |
| /* mark port as closing but in use; we can drop port lock |
| * and sleep if necessary |
| */ |
| port->openclose = true; |
| port->port.count = 0; |
| |
| gser = port->port_usb; |
| if (gser && gser->disconnect) |
| gser->disconnect(gser); |
| |
| /* wait for circular write buffer to drain, disconnect, or at |
| * most GS_CLOSE_TIMEOUT seconds; then discard the rest |
| */ |
| if (gs_buf_data_avail(&port->port_write_buf) > 0 && gser) { |
| spin_unlock_irq(&port->port_lock); |
| wait_event_interruptible_timeout(port->drain_wait, |
| gs_writes_finished(port), |
| GS_CLOSE_TIMEOUT * HZ); |
| spin_lock_irq(&port->port_lock); |
| gser = port->port_usb; |
| } |
| |
| /* Iff we're disconnected, there can be no I/O in flight so it's |
| * ok to free the circular buffer; else just scrub it. And don't |
| * let the push tasklet fire again until we're re-opened. |
| */ |
| if (gser == NULL) |
| gs_buf_free(&port->port_write_buf); |
| else |
| gs_buf_clear(&port->port_write_buf); |
| |
| tty->driver_data = NULL; |
| port->port.tty = NULL; |
| |
| port->openclose = false; |
| |
| pr_debug("gs_close: ttyGS%d (%p,%p) done!\n", |
| port->port_num, tty, file); |
| |
| wake_up_interruptible(&port->port.close_wait); |
| exit: |
| spin_unlock_irq(&port->port_lock); |
| } |
| |
| static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count) |
| { |
| struct gs_port *port = tty->driver_data; |
| unsigned long flags; |
| int status; |
| |
| pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n", |
| port->port_num, tty, count); |
| |
| spin_lock_irqsave(&port->port_lock, flags); |
| if (count) |
| count = gs_buf_put(&port->port_write_buf, buf, count); |
| /* treat count == 0 as flush_chars() */ |
| if (port->port_usb) |
| status = gs_start_tx(port); |
| spin_unlock_irqrestore(&port->port_lock, flags); |
| |
| return count; |
| } |
| |
| static int gs_put_char(struct tty_struct *tty, unsigned char ch) |
| { |
| struct gs_port *port = tty->driver_data; |
| unsigned long flags; |
| int status; |
| |
| pr_vdebug("gs_put_char: (%d,%p) char=0x%x, called from %p\n", |
| port->port_num, tty, ch, __builtin_return_address(0)); |
| |
| spin_lock_irqsave(&port->port_lock, flags); |
| status = gs_buf_put(&port->port_write_buf, &ch, 1); |
| spin_unlock_irqrestore(&port->port_lock, flags); |
| |
| return status; |
| } |
| |
| static void gs_flush_chars(struct tty_struct *tty) |
| { |
| struct gs_port *port = tty->driver_data; |
| unsigned long flags; |
| |
| pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty); |
| |
| spin_lock_irqsave(&port->port_lock, flags); |
| if (port->port_usb) |
| gs_start_tx(port); |
| spin_unlock_irqrestore(&port->port_lock, flags); |
| } |
| |
| static int gs_write_room(struct tty_struct *tty) |
| { |
| struct gs_port *port = tty->driver_data; |
| unsigned long flags; |
| int room = 0; |
| |
| spin_lock_irqsave(&port->port_lock, flags); |
| if (port->port_usb) |
| room = gs_buf_space_avail(&port->port_write_buf); |
| spin_unlock_irqrestore(&port->port_lock, flags); |
| |
| pr_vdebug("gs_write_room: (%d,%p) room=%d\n", |
| port->port_num, tty, room); |
| |
| return room; |
| } |
| |
| static int gs_chars_in_buffer(struct tty_struct *tty) |
| { |
| struct gs_port *port = tty->driver_data; |
| unsigned long flags; |
| int chars = 0; |
| |
| spin_lock_irqsave(&port->port_lock, flags); |
| chars = gs_buf_data_avail(&port->port_write_buf); |
| spin_unlock_irqrestore(&port->port_lock, flags); |
| |
| pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%d\n", |
| port->port_num, tty, chars); |
| |
| return chars; |
| } |
| |
| /* undo side effects of setting TTY_THROTTLED */ |
| static void gs_unthrottle(struct tty_struct *tty) |
| { |
| struct gs_port *port = tty->driver_data; |
| unsigned long flags; |
| |
| spin_lock_irqsave(&port->port_lock, flags); |
| if (port->port_usb) { |
| /* Kickstart read queue processing. We don't do xon/xoff, |
| * rts/cts, or other handshaking with the host, but if the |
| * read queue backs up enough we'll be NAKing OUT packets. |
| */ |
| tasklet_schedule(&port->push); |
| pr_vdebug(PREFIX "%d: unthrottle\n", port->port_num); |
| } |
| spin_unlock_irqrestore(&port->port_lock, flags); |
| } |
| |
| static int gs_break_ctl(struct tty_struct *tty, int duration) |
| { |
| struct gs_port *port = tty->driver_data; |
| int status = 0; |
| struct gserial *gser; |
| |
| pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n", |
| port->port_num, duration); |
| |
| spin_lock_irq(&port->port_lock); |
| gser = port->port_usb; |
| if (gser && gser->send_break) |
| status = gser->send_break(gser, duration); |
| spin_unlock_irq(&port->port_lock); |
| |
| return status; |
| } |
| |
| static const struct tty_operations gs_tty_ops = { |
| .open = gs_open, |
| .close = gs_close, |
| .write = gs_write, |
| .put_char = gs_put_char, |
| .flush_chars = gs_flush_chars, |
| .write_room = gs_write_room, |
| .chars_in_buffer = gs_chars_in_buffer, |
| .unthrottle = gs_unthrottle, |
| .break_ctl = gs_break_ctl, |
| }; |
| |
| /*-------------------------------------------------------------------------*/ |
| |
| static struct tty_driver *gs_tty_driver; |
| |
| static int |
| 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; |
| |
| tty_port_init(&port->port); |
| spin_lock_init(&port->port_lock); |
| init_waitqueue_head(&port->drain_wait); |
| |
| tasklet_init(&port->push, gs_rx_push, (unsigned long) port); |
| |
| INIT_LIST_HEAD(&port->read_pool); |
| INIT_LIST_HEAD(&port->read_queue); |
| INIT_LIST_HEAD(&port->write_pool); |
| |
| port->port_num = port_num; |
| port->port_line_coding = *coding; |
| |
| ports[port_num].port = port; |
| |
| return 0; |
| } |
| |
| /** |
| * gserial_setup - initialize TTY driver for one or more ports |
| * @g: gadget to associate with these ports |
| * @count: how many ports to support |
| * Context: may sleep |
| * |
| * The TTY stack needs to know in advance how many devices it should |
| * plan to manage. Use this call to set up the ports you will be |
| * exporting through USB. Later, connect them to functions based |
| * on what configuration is activated by the USB host; and disconnect |
| * them as appropriate. |
| * |
| * An example would be a two-configuration device in which both |
| * configurations expose port 0, but through different functions. |
| * One configuration could even expose port 1 while the other |
| * one doesn't. |
| * |
| * Returns negative errno or zero. |
| */ |
| int 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->driver_name = "g_serial"; |
| gs_tty_driver->name = PREFIX; |
| /* uses dynamically assigned dev_t values */ |
| |
| gs_tty_driver->type = TTY_DRIVER_TYPE_SERIAL; |
| gs_tty_driver->subtype = SERIAL_TYPE_NORMAL; |
| gs_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV; |
| gs_tty_driver->init_termios = tty_std_termios; |
| |
| /* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on |
| * MS-Windows. Otherwise, most of these flags shouldn't affect |
| * anything unless we were to actually hook up to a serial line. |
| */ |
| gs_tty_driver->init_termios.c_cflag = |
| B9600 | CS8 | CREAD | HUPCL | CLOCAL; |
| gs_tty_driver->init_termios.c_ispeed = 9600; |
| gs_tty_driver->init_termios.c_ospeed = 9600; |
| |
| coding.dwDTERate = cpu_to_le32(9600); |
| coding.bCharFormat = 8; |
| coding.bParityType = USB_CDC_NO_PARITY; |
| coding.bDataBits = USB_CDC_1_STOP_BITS; |
| |
| tty_set_operations(gs_tty_driver, &gs_tty_ops); |
| |
| /* make devices be openable */ |
| for (i = 0; i < count; i++) { |
| mutex_init(&ports[i].lock); |
| status = gs_port_alloc(i, &coding); |
| if (status) { |
| count = i; |
| goto fail; |
| } |
| } |
| n_ports = count; |
| |
| /* export the driver ... */ |
| status = tty_register_driver(gs_tty_driver); |
| if (status) { |
| pr_err("%s: cannot register, err %d\n", |
| __func__, status); |
| goto fail; |
| } |
| |
| /* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */ |
| for (i = 0; i < count; i++) { |
| struct device *tty_dev; |
| |
| tty_dev = tty_register_device(gs_tty_driver, i, &g->dev); |
| if (IS_ERR(tty_dev)) |
| pr_warning("%s: no classdev for port %d, err %ld\n", |
| __func__, i, PTR_ERR(tty_dev)); |
| } |
| |
| pr_debug("%s: registered %d ttyGS* device%s\n", __func__, |
| count, (count == 1) ? "" : "s"); |
| |
| return status; |
| fail: |
| while (count--) |
| kfree(ports[count].port); |
| put_tty_driver(gs_tty_driver); |
| gs_tty_driver = NULL; |
| return status; |
| } |
| |
| static int gs_closed(struct gs_port *port) |
| { |
| int cond; |
| |
| spin_lock_irq(&port->port_lock); |
| cond = (port->port.count == 0) && !port->openclose; |
| spin_unlock_irq(&port->port_lock); |
| return cond; |
| } |
| |
| /** |
| * gserial_cleanup - remove TTY-over-USB driver and devices |
| * Context: may sleep |
| * |
| * This is called to free all resources allocated by @gserial_setup(). |
| * Accordingly, it may need to wait until some open /dev/ files have |
| * closed. |
| * |
| * The caller must have issued @gserial_disconnect() for any ports |
| * that had previously been connected, so that there is never any |
| * I/O pending when it's called. |
| */ |
| void gserial_cleanup(void) |
| { |
| unsigned i; |
| struct gs_port *port; |
| |
| if (!gs_tty_driver) |
| return; |
| |
| /* start sysfs and /dev/ttyGS* node removal */ |
| for (i = 0; i < n_ports; i++) |
| tty_unregister_device(gs_tty_driver, i); |
| |
| for (i = 0; i < n_ports; i++) { |
| /* prevent new opens */ |
| mutex_lock(&ports[i].lock); |
| port = ports[i].port; |
| ports[i].port = NULL; |
| mutex_unlock(&ports[i].lock); |
| |
| tasklet_kill(&port->push); |
| |
| /* wait for old opens to finish */ |
| wait_event(port->port.close_wait, gs_closed(port)); |
| |
| WARN_ON(port->port_usb != NULL); |
| |
| kfree(port); |
| } |
| n_ports = 0; |
| |
| tty_unregister_driver(gs_tty_driver); |
| put_tty_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); |
| 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); |
| } |
| |
| 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->port.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->port.count == 0 && !port->openclose) |
| gs_buf_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); |
| } |