USB: g_serial: don't set low_latency flag
[linux-3.10.git] / drivers / usb / gadget / u_serial.c
index abf9505..a0f79df 100644 (file)
@@ -23,6 +23,7 @@
 #include <linux/delay.h>
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
+#include <linux/slab.h>
 
 #include "u_serial.h"
 
  * 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}().
+ * 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
  *
@@ -100,6 +104,8 @@ struct gs_port {
        wait_queue_head_t       close_wait;     /* wait for last close */
 
        struct list_head        read_pool;
+       struct list_head        read_queue;
+       unsigned                n_read;
        struct tasklet_struct   push;
 
        struct list_head        write_pool;
@@ -177,7 +183,7 @@ static void gs_buf_clear(struct gs_buf *gb)
 /*
  * gs_buf_data_avail
  *
- * Return the number of bytes of data available in the circular
+ * Return the number of bytes of data written into the circular
  * buffer.
  */
 static unsigned gs_buf_data_avail(struct gs_buf *gb)
@@ -278,7 +284,7 @@ gs_buf_get(struct gs_buf *gb, char *buf, unsigned count)
  * 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 *
+struct usb_request *
 gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
 {
        struct usb_request *req;
@@ -302,7 +308,7 @@ gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
  *
  * Free a usb_request and its buffer.
  */
-static void gs_free_req(struct usb_ep *ep, struct usb_request *req)
+void gs_free_req(struct usb_ep *ep, struct usb_request *req)
 {
        kfree(req->buf);
        usb_ep_free_request(ep, req);
@@ -366,12 +372,11 @@ __acquires(&port->port_lock)
 
                req->length = len;
                list_del(&req->list);
+               req->zero = (gs_buf_data_avail(&port->port_write_buf) == 0);
 
-#ifdef VERBOSE_DEBUG
-               pr_debug("%s: %s, len=%d, 0x%02x 0x%02x 0x%02x ...\n",
-                               __func__, in->name, len, *((u8 *)req->buf),
+               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));
-#endif
 
                /* Drop lock while we call out of driver; completions
                 * could be issued while we do so.  Disconnection may
@@ -401,56 +406,6 @@ __acquires(&port->port_lock)
        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
  */
@@ -469,9 +424,9 @@ __acquires(&port->port_lock)
                int                     status;
                struct tty_struct       *tty;
 
-               /* no more rx if closed or throttled */
+               /* no more rx if closed */
                tty = port->port_tty;
-               if (!tty || test_bit(TTY_THROTTLED, &tty->flags))
+               if (!tty)
                        break;
 
                req = list_entry(pool->next, struct usb_request, list);
@@ -500,36 +455,128 @@ __acquires(&port->port_lock)
        return started;
 }
 
-static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
+/*
+ * 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)
 {
-       int             status;
-       struct gs_port  *port = ep->driver_data;
+       struct gs_port          *port = (void *)_port;
+       struct tty_struct       *tty;
+       struct list_head        *queue = &port->read_queue;
+       bool                    disconnect = false;
+       bool                    do_push = false;
 
-       spin_lock(&port->port_lock);
-       list_add(&req->list, &port->read_pool);
+       /* 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;
 
-       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;
+               req = list_first_entry(queue, struct usb_request, list);
 
-       case -ESHUTDOWN:
-               /* disconnect */
-               pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
-               break;
+               /* discard data if tty was closed */
+               if (!tty)
+                       goto recycle;
 
-       default:
-               /* presumably a transient fault */
-               pr_warning("%s: unexpected %s status %d\n",
-                               __func__, ep->name, req->status);
-               gs_start_rx(port);
-               break;
+               /* 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);
+       }
+
+       /* 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);
 }
 
@@ -625,6 +672,7 @@ static int gs_start_io(struct gs_port *port)
        }
 
        /* queue read requests */
+       port->n_read = 0;
        started = gs_start_rx(port);
 
        /* unblock any pending writes into our circular buffer */
@@ -633,9 +681,10 @@ static int gs_start_io(struct gs_port *port)
        } else {
                gs_free_requests(ep, head);
                gs_free_requests(port->port_usb->in, &port->write_pool);
+               status = -EIO;
        }
 
-       return started ? 0 : status;
+       return status;
 }
 
 /*-------------------------------------------------------------------------*/
@@ -729,17 +778,15 @@ static int gs_open(struct tty_struct *tty, struct file *file)
        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) {
+               struct gserial  *gser = 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 */
+               if (gser->connect)
+                       gser->connect(gser);
        }
 
        pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
@@ -766,6 +813,7 @@ static int gs_writes_finished(struct gs_port *p)
 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);
 
@@ -785,32 +833,31 @@ static void gs_close(struct tty_struct *tty, struct file *file)
        port->openclose = true;
        port->open_count = 0;
 
-       if (port->port_usb)
-               /* REVISIT for ACM, issue "network disconnected" event */;
+       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
-                       && port->port_usb) {
+       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 (port->port_usb == NULL)
+       if (gser == 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;
 
@@ -911,15 +958,35 @@ 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);
+       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);
 
-       pr_vdebug("gs_unthrottle: ttyGS%d, %d packets\n",
-                       port->port_num, started);
+       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 = {
@@ -931,6 +998,7 @@ static const struct tty_operations gs_tty_ops = {
        .write_room =           gs_write_room,
        .chars_in_buffer =      gs_chars_in_buffer,
        .unthrottle =           gs_unthrottle,
+       .break_ctl =            gs_break_ctl,
 };
 
 /*-------------------------------------------------------------------------*/
@@ -953,6 +1021,7 @@ gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
        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;
@@ -997,7 +1066,7 @@ int __init gserial_setup(struct usb_gadget *g, unsigned count)
 
        gs_tty_driver->owner = THIS_MODULE;
        gs_tty_driver->driver_name = "g_serial";
-       gs_tty_driver->name = "ttyGS";
+       gs_tty_driver->name = PREFIX;
        /* uses dynamically assigned dev_t values */
 
        gs_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
@@ -1014,7 +1083,7 @@ int __init gserial_setup(struct usb_gadget *g, unsigned count)
        gs_tty_driver->init_termios.c_ispeed = 9600;
        gs_tty_driver->init_termios.c_ospeed = 9600;
 
-       coding.dwDTERate = __constant_cpu_to_le32(9600);
+       coding.dwDTERate = cpu_to_le32(9600);
        coding.bCharFormat = 8;
        coding.bParityType = USB_CDC_NO_PARITY;
        coding.bDataBits = USB_CDC_1_STOP_BITS;
@@ -1035,7 +1104,6 @@ int __init gserial_setup(struct usb_gadget *g, unsigned 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;
@@ -1104,6 +1172,8 @@ void gserial_cleanup(void)
                ports[i].port = NULL;
                mutex_unlock(&ports[i].lock);
 
+               tasklet_kill(&port->push);
+
                /* wait for old opens to finish */
                wait_event(port->close_wait, gs_closed(port));
 
@@ -1175,14 +1245,17 @@ int gserial_connect(struct gserial *gser, u8 port_num)
 
        /* 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 ... and notify the serial
+        * protocol about open/close status (connect/disconnect).
         */
-
-       /* 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);
+               if (gser->connect)
+                       gser->connect(gser);
+       } else {
+               if (gser->disconnect)
+                       gser->disconnect(gser);
        }
 
        spin_unlock_irqrestore(&port->port_lock, flags);
@@ -1241,6 +1314,7 @@ void gserial_disconnect(struct gserial *gser)
        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->out, &port->read_queue);
        gs_free_requests(gser->in, &port->write_pool);
        spin_unlock_irqrestore(&port->port_lock, flags);
 }