USB: aircable: rewrite using generic read and write implementations

Kill circular buffers for tx and rx as well as read work thread, and
switch to generic kfifo-based write implementation.

This is an example of how prepare_write_buffer and process_read_urb can
be used to handle protocols with packet headers.

Please note the diffstat which shows that the same functionality is now
provided using only a tenth of the code (including whitespace and
comments, though).

Tested-by: Naranjo, Manuel Francisco <naranjo.manuel@gmail.com>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 47 insertions, 453 deletions

diff --git a/drivers/usb/serial/aircable.c b/drivers/usb/serial/aircable.c
index 4fd7af98b1ae..cac5162937b3 100644
--- a/drivers/usb/serial/aircable.c
+++ b/drivers/usb/serial/aircable.c
@@ -1,7 +1,9 @@
 /*
  * AIRcable USB Bluetooth Dongle Driver.
  *
+ * Copyright (C) 2010 Johan Hovold <jhovold@gmail.com>
  * Copyright (C) 2006 Manuel Francisco Naranjo (naranjo.manuel@gmail.com)
+ *
  * This program is free software; you can redistribute it and/or modify it under
  * the terms of the GNU General Public License version 2 as published by the
  * Free Software Foundation.
@@ -42,10 +44,10 @@
  *
  */
 
+#include <asm/unaligned.h>
 #include <linux/tty.h>
 #include <linux/slab.h>
 #include <linux/tty_flip.h>
-#include <linux/circ_buf.h>
 #include <linux/usb.h>
 #include <linux/usb/serial.h>
 
@@ -55,16 +57,12 @@ static int debug;
 #define AIRCABLE_VID            0x16CA
 #define AIRCABLE_USB_PID        0x1502
 
-/* write buffer size defines */
-#define AIRCABLE_BUF_SIZE       2048
-
 /* Protocol Stuff */
 #define HCI_HEADER_LENGTH       0x4
 #define TX_HEADER_0             0x20
 #define TX_HEADER_1             0x29
 #define RX_HEADER_0             0x00
 #define RX_HEADER_1             0x20
-#define MAX_HCI_FRAMESIZE       60
 #define HCI_COMPLETE_FRAME      64
 
 /* rx_flags */
@@ -74,8 +72,8 @@ static int debug;
 /*
  * Version Information
  */
-#define DRIVER_VERSION "v1.0b2"
-#define DRIVER_AUTHOR "Naranjo, Manuel Francisco <naranjo.manuel@gmail.com>"
+#define DRIVER_VERSION "v2.0"
+#define DRIVER_AUTHOR "Naranjo, Manuel Francisco <naranjo.manuel@gmail.com>, Johan Hovold <jhovold@gmail.com>"
 #define DRIVER_DESC "AIRcable USB Driver"
 
 /* ID table that will be registered with USB core */
@@ -85,225 +83,19 @@ static const struct usb_device_id id_table[] = {
 };
 MODULE_DEVICE_TABLE(usb, id_table);
 
-
-/* Internal Structure */
-struct aircable_private {
-        spinlock_t rx_lock;             /* spinlock for the receive lines */
-        struct circ_buf *tx_buf;        /* write buffer */
-        struct circ_buf *rx_buf;        /* read buffer */
-        int rx_flags;                   /* for throttilng */
-        struct work_struct rx_work;     /* work cue for the receiving line */
-        struct usb_serial_port *port;   /* USB port with which associated */
-};
-
-/* Private methods */
-
-/* Circular Buffer Methods, code from ti_usb_3410_5052 used */
-/*
- * serial_buf_clear
- *
- * Clear out all data in the circular buffer.
- */
-static void serial_buf_clear(struct circ_buf *cb)
-{
-        cb->head = cb->tail = 0;
-}
-
-/*
- * serial_buf_alloc
- *
- * Allocate a circular buffer and all associated memory.
- */
-static struct circ_buf *serial_buf_alloc(void)
-{
-        struct circ_buf *cb;
-        cb = kmalloc(sizeof(struct circ_buf), GFP_KERNEL);
-        if (cb == NULL)
-                return NULL;
-        cb->buf = kmalloc(AIRCABLE_BUF_SIZE, GFP_KERNEL);
-        if (cb->buf == NULL) {
-                kfree(cb);
-                return NULL;
-        }
-        serial_buf_clear(cb);
-        return cb;
-}
-
-/*
- * serial_buf_free
- *
- * Free the buffer and all associated memory.
- */
-static void serial_buf_free(struct circ_buf *cb)
-{
-        kfree(cb->buf);
-        kfree(cb);
-}
-
-/*
- * serial_buf_data_avail
- *
- * Return the number of bytes of data available in the circular
- * buffer.
- */
-static int serial_buf_data_avail(struct circ_buf *cb)
-{
-        return CIRC_CNT(cb->head, cb->tail, AIRCABLE_BUF_SIZE);
-}
-
-/*
- * serial_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 int serial_buf_put(struct circ_buf *cb, const char *buf, int count)
-{
-        int c, ret = 0;
-        while (1) {
-                c = CIRC_SPACE_TO_END(cb->head, cb->tail, AIRCABLE_BUF_SIZE);
-                if (count < c)
-                        c = count;
-                if (c <= 0)
-                        break;
-                memcpy(cb->buf + cb->head, buf, c);
-                cb->head = (cb->head + c) & (AIRCABLE_BUF_SIZE-1);
-                buf += c;
-                count -= c;
-                ret = c;
-        }
-        return ret;
-}
-
-/*
- * serial_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 int serial_buf_get(struct circ_buf *cb, char *buf, int count)
-{
-        int c, ret = 0;
-        while (1) {
-                c = CIRC_CNT_TO_END(cb->head, cb->tail, AIRCABLE_BUF_SIZE);
-                if (count < c)
-                        c = count;
-                if (c <= 0)
-                        break;
-                memcpy(buf, cb->buf + cb->tail, c);
-                cb->tail = (cb->tail + c) & (AIRCABLE_BUF_SIZE-1);
-                buf += c;
-                count -= c;
-                ret = c;
-        }
-        return ret;
-}
-
-/* End of circula buffer methods */
-
-static void aircable_send(struct usb_serial_port *port)
+static int aircable_prepare_write_buffer(struct usb_serial_port *port,
+                void **dest, size_t size, const void *src, size_t count)
 {
-        int count, result;
-        struct aircable_private *priv = usb_get_serial_port_data(port);
-        unsigned char *buf;
-        __le16 *dbuf;
-        dbg("%s - port %d", __func__, port->number);
-        if (port->write_urb_busy)
-                return;
-
-        count = min(serial_buf_data_avail(priv->tx_buf), MAX_HCI_FRAMESIZE);
-        if (count == 0)
-                return;
-
-        buf = kzalloc(count + HCI_HEADER_LENGTH, GFP_ATOMIC);
-        if (!buf) {
-                dev_err(&port->dev, "%s- kzalloc(%d) failed.\n",
-                        __func__, count + HCI_HEADER_LENGTH);
-                return;
-        }
+        unsigned char *buf = *dest;
 
+        count = kfifo_out_locked(&port->write_fifo, buf + HCI_HEADER_LENGTH,
+                                        size - HCI_HEADER_LENGTH, &port->lock);
         buf[0] = TX_HEADER_0;
         buf[1] = TX_HEADER_1;
-        dbuf = (__le16 *)&buf[2];
-        *dbuf = cpu_to_le16((u16)count);
-        serial_buf_get(priv->tx_buf, buf + HCI_HEADER_LENGTH,
-                                                        MAX_HCI_FRAMESIZE);
-
-        memcpy(port->write_urb->transfer_buffer, buf,
-               count + HCI_HEADER_LENGTH);
-
-        kfree(buf);
-        port->write_urb_busy = 1;
-        usb_serial_debug_data(debug, &port->dev, __func__,
-                              count + HCI_HEADER_LENGTH,
-                              port->write_urb->transfer_buffer);
-        port->write_urb->transfer_buffer_length = count + HCI_HEADER_LENGTH;
-        port->write_urb->dev = port->serial->dev;
-        result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
-
-        if (result) {
-                dev_err(&port->dev,
-                        "%s - failed submitting write urb, error %d\n",
-                        __func__, result);
-                port->write_urb_busy = 0;
-        }
-
-        schedule_work(&port->work);
-}
-
-static void aircable_read(struct work_struct *work)
-{
-        struct aircable_private *priv =
-                container_of(work, struct aircable_private, rx_work);
-        struct usb_serial_port *port = priv->port;
-        struct tty_struct *tty;
-        unsigned char *data;
-        int count;
-        if (priv->rx_flags & THROTTLED) {
-                if (priv->rx_flags & ACTUALLY_THROTTLED)
-                        schedule_work(&priv->rx_work);
-                return;
-        }
-
-        /* By now I will flush data to the tty in packages of no more than
-         * 64 bytes, to ensure I do not get throttled.
-         * Ask USB mailing list for better aproach.
-         */
-        tty = tty_port_tty_get(&port->port);
-
-        if (!tty) {
-                schedule_work(&priv->rx_work);
-                dev_err(&port->dev, "%s - No tty available\n", __func__);
-                return ;
-        }
-
-        count = min(64, serial_buf_data_avail(priv->rx_buf));
-
-        if (count <= 0)
-                goto out; /* We have finished sending everything. */
+        put_unaligned_le16(count, &buf[2]);
 
-        tty_prepare_flip_string(tty, &data, count);
-        if (!data) {
-                dev_err(&port->dev, "%s- kzalloc(%d) failed.",
-                                                        __func__, count);
-                goto out;
-        }
-
-        serial_buf_get(priv->rx_buf, data, count);
-
-        tty_flip_buffer_push(tty);
-
-        if (serial_buf_data_avail(priv->rx_buf))
-                schedule_work(&priv->rx_work);
-out:            
-        tty_kref_put(tty);
-        return;
+        return count;
 }
-/* End of private methods */
 
 static int aircable_probe(struct usb_serial *serial,
                           const struct usb_device_id *id)
@@ -330,247 +122,50 @@ static int aircable_probe(struct usb_serial *serial,
         return 0;
 }
 
-static int aircable_attach(struct usb_serial *serial)
-{
-        struct usb_serial_port *port = serial->port[0];
-        struct aircable_private *priv;
-
-        priv = kzalloc(sizeof(struct aircable_private), GFP_KERNEL);
-        if (!priv) {
-                dev_err(&port->dev, "%s- kmalloc(%Zd) failed.\n", __func__,
-                        sizeof(struct aircable_private));
-                return -ENOMEM;
-        }
-
-        /* Allocation of Circular Buffers */
-        priv->tx_buf = serial_buf_alloc();
-        if (priv->tx_buf == NULL) {
-                kfree(priv);
-                return -ENOMEM;
-        }
-
-        priv->rx_buf = serial_buf_alloc();
-        if (priv->rx_buf == NULL) {
-                kfree(priv->tx_buf);
-                kfree(priv);
-                return -ENOMEM;
-        }
-
-        priv->rx_flags &= ~(THROTTLED | ACTUALLY_THROTTLED);
-        priv->port = port;
-        INIT_WORK(&priv->rx_work, aircable_read);
-
-        usb_set_serial_port_data(serial->port[0], priv);
-
-        return 0;
-}
-
-static void aircable_release(struct usb_serial *serial)
-{
-
-        struct usb_serial_port *port = serial->port[0];
-        struct aircable_private *priv = usb_get_serial_port_data(port);
-
-        dbg("%s", __func__);
-
-        if (priv) {
-                serial_buf_free(priv->tx_buf);
-                serial_buf_free(priv->rx_buf);
-                kfree(priv);
-        }
-}
-
-static int aircable_write_room(struct tty_struct *tty)
-{
-        struct usb_serial_port *port = tty->driver_data;
-        struct aircable_private *priv = usb_get_serial_port_data(port);
-        return serial_buf_data_avail(priv->tx_buf);
-}
-
-static int aircable_write(struct tty_struct *tty, struct usb_serial_port *port,
-                          const unsigned char *source, int count)
+static int aircable_process_packet(struct tty_struct *tty,
+                        struct usb_serial_port *port, int has_headers,
+                        char *packet, int len)
 {
-        struct aircable_private *priv = usb_get_serial_port_data(port);
-        int temp;
-
-        dbg("%s - port %d, %d bytes", __func__, port->number, count);
-
-        usb_serial_debug_data(debug, &port->dev, __func__, count, source);
-
-        if (!count) {
-                dbg("%s - write request of 0 bytes", __func__);
-                return count;
+        if (has_headers) {
+                len -= HCI_HEADER_LENGTH;
+                packet += HCI_HEADER_LENGTH;
         }
-
-        temp = serial_buf_put(priv->tx_buf, source, count);
-
-        aircable_send(port);
-
-        if (count > AIRCABLE_BUF_SIZE)
-                count = AIRCABLE_BUF_SIZE;
-
-        return count;
-
-}
-
-static void aircable_write_bulk_callback(struct urb *urb)
-{
-        struct usb_serial_port *port = urb->context;
-        int status = urb->status;
-        int result;
-
-        dbg("%s - urb status: %d", __func__ , status);
-
-        /* This has been taken from cypress_m8.c cypress_write_int_callback */
-        switch (status) {
-        case 0:
-                /* success */
-                break;
-        case -ECONNRESET:
-        case -ENOENT:
-        case -ESHUTDOWN:
-                /* this urb is terminated, clean up */
-                dbg("%s - urb shutting down with status: %d",
-                    __func__, status);
-                port->write_urb_busy = 0;
-                return;
-        default:
-                /* error in the urb, so we have to resubmit it */
-                dbg("%s - Overflow in write", __func__);
-                dbg("%s - nonzero write bulk status received: %d",
-                    __func__, status);
-                port->write_urb->transfer_buffer_length = 1;
-                port->write_urb->dev = port->serial->dev;
-                result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
-                if (result)
-                        dev_err(&urb->dev->dev,
-                            "%s - failed resubmitting write urb, error %d\n",
-                                                        __func__, result);
-                else
-                        return;
+        if (len <= 0) {
+                dbg("%s - malformed packet", __func__);
+                return 0;
         }
 
-        port->write_urb_busy = 0;
+        tty_insert_flip_string(tty, packet, len);
 
-        aircable_send(port);
+        return len;
 }
 
-static void aircable_read_bulk_callback(struct urb *urb)
+static void aircable_process_read_urb(struct urb *urb)
 {
         struct usb_serial_port *port = urb->context;
-        struct aircable_private *priv = usb_get_serial_port_data(port);
+        char *data = (char *)urb->transfer_buffer;
         struct tty_struct *tty;
-        unsigned long no_packages, remaining, package_length, i;
-        int result, shift = 0;
-        unsigned char *temp;
-        int status = urb->status;
-
-        dbg("%s - port %d", __func__, port->number);
-
-        if (status) {
-                dbg("%s - urb status = %d", __func__, status);
-                if (status == -EPROTO) {
-                        dbg("%s - caught -EPROTO, resubmitting the urb",
-                            __func__);
-                        usb_fill_bulk_urb(port->read_urb, port->serial->dev,
-                                usb_rcvbulkpipe(port->serial->dev,
-                                        port->bulk_in_endpointAddress),
-                                port->read_urb->transfer_buffer,
-                                port->read_urb->transfer_buffer_length,
-                                aircable_read_bulk_callback, port);
-
-                        result = usb_submit_urb(urb, GFP_ATOMIC);
-                        if (result)
-                                dev_err(&urb->dev->dev,
-                                        "%s - failed resubmitting read urb, error %d\n",
-                                        __func__, result);
-                        return;
-                }
-                dbg("%s - unable to handle the error, exiting.", __func__);
-                return;
-        }
-
-        usb_serial_debug_data(debug, &port->dev, __func__,
-                                urb->actual_length, urb->transfer_buffer);
+        int has_headers;
+        int count;
+        int len;
+        int i;
 
         tty = tty_port_tty_get(&port->port);
-        if (tty && urb->actual_length) {
-                if (urb->actual_length <= 2) {
-                        /* This is an incomplete package */
-                        serial_buf_put(priv->rx_buf, urb->transfer_buffer,
-                                       urb->actual_length);
-                } else {
-                        temp = urb->transfer_buffer;
-                        if (temp[0] == RX_HEADER_0)
-                                shift = HCI_HEADER_LENGTH;
-
-                        remaining = urb->actual_length;
-                        no_packages = urb->actual_length / (HCI_COMPLETE_FRAME);
-
-                        if (urb->actual_length % HCI_COMPLETE_FRAME != 0)
-                                no_packages++;
+        if (!tty)
+                return;
 
-                        for (i = 0; i < no_packages; i++) {
-                                if (remaining > (HCI_COMPLETE_FRAME))
-                                        package_length = HCI_COMPLETE_FRAME;
-                                else
-                                        package_length = remaining;
-                                remaining -= package_length;
+        has_headers = (urb->actual_length > 2 && data[0] == RX_HEADER_0);
 
-                                serial_buf_put(priv->rx_buf,
-                                        urb->transfer_buffer + shift +
-                                        (HCI_COMPLETE_FRAME) * (i),
-                                        package_length - shift);
-                        }
-                }
-                aircable_read(&priv->rx_work);
+        count = 0;
+        for (i = 0; i < urb->actual_length; i += HCI_COMPLETE_FRAME) {
+                len = min_t(int, urb->actual_length - i, HCI_COMPLETE_FRAME);
+                count += aircable_process_packet(tty, port, has_headers,
+                                                                &data[i], len);
         }
-        tty_kref_put(tty);
-
-        /* Schedule the next read */
-        usb_fill_bulk_urb(port->read_urb, port->serial->dev,
-                          usb_rcvbulkpipe(port->serial->dev,
-                                  port->bulk_in_endpointAddress),
-                          port->read_urb->transfer_buffer,
-                          port->read_urb->transfer_buffer_length,
-                          aircable_read_bulk_callback, port);
-
-        result = usb_submit_urb(urb, GFP_ATOMIC);
-        if (result && result != -EPERM)
-                dev_err(&urb->dev->dev,
-                        "%s - failed resubmitting read urb, error %d\n",
-                        __func__, result);
-}
-
-/* Based on ftdi_sio.c throttle */
-static void aircable_throttle(struct tty_struct *tty)
-{
-        struct usb_serial_port *port = tty->driver_data;
-        struct aircable_private *priv = usb_get_serial_port_data(port);
-
-        dbg("%s - port %d", __func__, port->number);
 
-        spin_lock_irq(&priv->rx_lock);
-        priv->rx_flags |= THROTTLED;
-        spin_unlock_irq(&priv->rx_lock);
-}
-
-/* Based on ftdi_sio.c unthrottle */
-static void aircable_unthrottle(struct tty_struct *tty)
-{
-        struct usb_serial_port *port = tty->driver_data;
-        struct aircable_private *priv = usb_get_serial_port_data(port);
-        int actually_throttled;
-
-        dbg("%s - port %d", __func__, port->number);
-
-        spin_lock_irq(&priv->rx_lock);
-        actually_throttled = priv->rx_flags & ACTUALLY_THROTTLED;
-        priv->rx_flags &= ~(THROTTLED | ACTUALLY_THROTTLED);
-        spin_unlock_irq(&priv->rx_lock);
-
-        if (actually_throttled)
-                schedule_work(&priv->rx_work);
+        if (count)
+                tty_flip_buffer_push(tty);
+        tty_kref_put(tty);
 }
 
 static struct usb_driver aircable_driver = {
@@ -589,15 +184,14 @@ static struct usb_serial_driver aircable_device = {
         .usb_driver =           &aircable_driver,
         .id_table =             id_table,
         .num_ports =            1,
-        .attach =               aircable_attach,
+        .bulk_out_size =        HCI_COMPLETE_FRAME,
+        /* Must modify prepare_write_buffer if multi_urb_write is changed. */
+        .multi_urb_write =      0,
         .probe =                aircable_probe,
-        .release =              aircable_release,
-        .write =                aircable_write,
-        .write_room =           aircable_write_room,
-        .write_bulk_callback =  aircable_write_bulk_callback,
-        .read_bulk_callback =   aircable_read_bulk_callback,
-        .throttle =             aircable_throttle,
-        .unthrottle =           aircable_unthrottle,
+        .process_read_urb =     aircable_process_read_urb,
+        .prepare_write_buffer = aircable_prepare_write_buffer,
+        .throttle =             usb_serial_generic_throttle,
+        .unthrottle =           usb_serial_generic_unthrottle,
 };
 
 static int __init aircable_init(void)