#include <linux/slab.h>
 #include <linux/stat.h>
 #include <linux/timer.h>
+#include <linux/types.h>
+#include <linux/usb_ch9.h>
 #include <linux/workqueue.h>
 
 #include "usbatm.h"
 
 #define RESUBMIT_DELAY         1000    /* milliseconds */
 
-#define DEFAULT_ALTSETTING     1
+#define DEFAULT_BULK_ALTSETTING        1
+#define DEFAULT_ISOC_ALTSETTING        2
 #define DEFAULT_DL_512_FIRST   0
+#define DEFAULT_ENABLE_ISOC    0
 #define DEFAULT_SW_BUFFERING   0
 
-static int altsetting = DEFAULT_ALTSETTING;
+static unsigned int altsetting = 0; /* zero means: use the default */
 static int dl_512_first = DEFAULT_DL_512_FIRST;
+static int enable_isoc = DEFAULT_ENABLE_ISOC;
 static int sw_buffering = DEFAULT_SW_BUFFERING;
 
-module_param(altsetting, int, S_IRUGO | S_IWUSR);
+module_param(altsetting, uint, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(altsetting,
-                "Alternative setting for data interface (default: "
-                __MODULE_STRING(DEFAULT_ALTSETTING) ")");
+               "Alternative setting for data interface (bulk_default: "
+               __MODULE_STRING(DEFAULT_BULK_ALTSETTING) "; isoc_default: "
+               __MODULE_STRING(DEFAULT_ISOC_ALTSETTING) ")");
 
 module_param(dl_512_first, bool, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(dl_512_first,
                 "Read 512 bytes before sending firmware (default: "
                 __MODULE_STRING(DEFAULT_DL_512_FIRST) ")");
 
+module_param(enable_isoc, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(enable_isoc,
+               "Use isochronous transfers if available (default: "
+               __MODULE_STRING(DEFAULT_ENABLE_ISOC) ")");
+
 module_param(sw_buffering, bool, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(sw_buffering,
                 "Enable software buffering (default: "
 
 #define INTERFACE_DATA         1
 #define ENDPOINT_INT           0x81
-#define ENDPOINT_DATA          0x07
+#define ENDPOINT_BULK_DATA     0x07
+#define ENDPOINT_ISOC_DATA     0x07
 #define ENDPOINT_FIRMWARE      0x05
 
 #define hex2int(c) ( (c >= '0') && (c <= '9') ? (c - '0') : ((c & 0xf) + 9) )
                         const struct usb_device_id *id)
 {
        struct usb_device *usb_dev = interface_to_usbdev(intf);
-       struct usb_interface *cur_intf;
+       struct usb_interface *cur_intf, *data_intf;
        struct speedtch_instance_data *instance;
        int ifnum = intf->altsetting->desc.bInterfaceNumber;
        int num_interfaces = usb_dev->actconfig->desc.bNumInterfaces;
        int i, ret;
+       int use_isoc;
 
        usb_dbg(usbatm, "%s entered\n", __func__);
 
                return -ENODEV;
        }
 
+       if (!(data_intf = usb_ifnum_to_if(usb_dev, INTERFACE_DATA))) {
+               usb_err(usbatm, "%s: data interface not found!\n", __func__);
+               return -ENODEV;
+       }
+
        /* claim all interfaces */
 
        for (i=0; i < num_interfaces; i++) {
 
        instance->usbatm = usbatm;
 
-       /* altsetting may change at any moment, so take a snapshot */
+       /* altsetting and enable_isoc may change at any moment, so take a snapshot */
        instance->altsetting = altsetting;
+       use_isoc = enable_isoc;
 
        if (instance->altsetting)
                if ((ret = usb_set_interface(usb_dev, INTERFACE_DATA, instance->altsetting)) < 0) {
                        instance->altsetting = 0; /* fall back to default */
                }
 
-       if (!instance->altsetting) {
-               if ((ret = usb_set_interface(usb_dev, INTERFACE_DATA, DEFAULT_ALTSETTING)) < 0) {
-                       usb_err(usbatm, "%s: setting interface to %2d failed (%d)!\n", __func__, DEFAULT_ALTSETTING, ret);
-                       goto fail_free;
+       if (!instance->altsetting && use_isoc)
+               if ((ret = usb_set_interface(usb_dev, INTERFACE_DATA, DEFAULT_ISOC_ALTSETTING)) < 0) {
+                       usb_dbg(usbatm, "%s: setting interface to %2d failed (%d)!\n", __func__, DEFAULT_ISOC_ALTSETTING, ret);
+                       use_isoc = 0; /* fall back to bulk */
                }
-               instance->altsetting = DEFAULT_ALTSETTING;
+
+       if (use_isoc) {
+               const struct usb_host_interface *desc = data_intf->cur_altsetting;
+               const __u8 target_address = USB_DIR_IN | usbatm->driver->isoc_in;
+               int i;
+
+               use_isoc = 0; /* fall back to bulk if endpoint not found */
+
+               for (i=0; i<desc->desc.bNumEndpoints; i++) {
+                       const struct usb_endpoint_descriptor *endpoint_desc = &desc->endpoint[i].desc;
+
+                       if ((endpoint_desc->bEndpointAddress == target_address)) {
+                               use_isoc = (endpoint_desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) ==
+                                       USB_ENDPOINT_XFER_ISOC;
+                               break;
+                       }
+               }
+
+               if (!use_isoc)
+                       usb_info(usbatm, "isochronous transfer not supported - using bulk\n");
        }
 
+       if (!use_isoc && !instance->altsetting)
+               if ((ret = usb_set_interface(usb_dev, INTERFACE_DATA, DEFAULT_BULK_ALTSETTING)) < 0) {
+                       usb_err(usbatm, "%s: setting interface to %2d failed (%d)!\n", __func__, DEFAULT_BULK_ALTSETTING, ret);
+                       goto fail_free;
+               }
+
+       if (!instance->altsetting)
+               instance->altsetting = use_isoc ? DEFAULT_ISOC_ALTSETTING : DEFAULT_BULK_ALTSETTING;
+
+       usbatm->flags |= (use_isoc ? UDSL_USE_ISOC : 0);
+
        INIT_WORK(&instance->status_checker, (void *)speedtch_check_status, instance);
 
        instance->status_checker.timer.function = speedtch_status_poll;
                              0x12, 0xc0, 0x07, 0x00,
                              instance->scratch_buffer + OFFSET_7, SIZE_7, 500);
 
-       usbatm->flags = (ret == SIZE_7 ? UDSL_SKIP_HEAVY_INIT : 0);
+       usbatm->flags |= (ret == SIZE_7 ? UDSL_SKIP_HEAVY_INIT : 0);
 
        usb_dbg(usbatm, "%s: firmware %s loaded\n", __func__, usbatm->flags & UDSL_SKIP_HEAVY_INIT ? "already" : "not");
 
        .unbind         = speedtch_unbind,
        .atm_start      = speedtch_atm_start,
        .atm_stop       = speedtch_atm_stop,
-       .in             = ENDPOINT_DATA,
-       .out            = ENDPOINT_DATA
+       .bulk_in        = ENDPOINT_BULK_DATA,
+       .bulk_out       = ENDPOINT_BULK_DATA,
+       .isoc_in        = ENDPOINT_ISOC_DATA
 };
 
 static int speedtch_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
 
        init_completion(&instance->thread_exited);
 
        INIT_LIST_HEAD(&instance->vcc_list);
+       skb_queue_head_init(&instance->sndqueue);
 
        usbatm_init_channel(&instance->rx_channel);
        usbatm_init_channel(&instance->tx_channel);
        tasklet_init(&instance->rx_channel.tasklet, usbatm_rx_process, (unsigned long)instance);
        tasklet_init(&instance->tx_channel.tasklet, usbatm_tx_process, (unsigned long)instance);
-       instance->rx_channel.endpoint = usb_rcvbulkpipe(usb_dev, driver->in);
-       instance->tx_channel.endpoint = usb_sndbulkpipe(usb_dev, driver->out);
        instance->rx_channel.stride = ATM_CELL_SIZE + driver->rx_padding;
        instance->tx_channel.stride = ATM_CELL_SIZE + driver->tx_padding;
        instance->rx_channel.usbatm = instance->tx_channel.usbatm = instance;
 
+       if ((instance->flags & UDSL_USE_ISOC) && driver->isoc_in)
+               instance->rx_channel.endpoint = usb_rcvisocpipe(usb_dev, driver->isoc_in);
+       else
+               instance->rx_channel.endpoint = usb_rcvbulkpipe(usb_dev, driver->bulk_in);
+
+       instance->tx_channel.endpoint = usb_sndbulkpipe(usb_dev, driver->bulk_out);
+
        /* tx buffer size must be a positive multiple of the stride */
        instance->tx_channel.buf_size = max (instance->tx_channel.stride,
                        snd_buf_bytes - (snd_buf_bytes % instance->tx_channel.stride));
                num_packets--;
 
        instance->rx_channel.buf_size = num_packets * maxpacket;
+       instance->rx_channel.packet_size = maxpacket;
 
 #ifdef DEBUG
        for (i = 0; i < 2; i++) {
        }
 #endif
 
-       skb_queue_head_init(&instance->sndqueue);
+       /* initialize urbs */
 
        for (i = 0; i < num_rcv_urbs + num_snd_urbs; i++) {
-               struct urb *urb;
                u8 *buffer;
-               unsigned int iso_packets = 0, iso_size = 0;
                struct usbatm_channel *channel = i < num_rcv_urbs ?
                        &instance->rx_channel : &instance->tx_channel;
+               struct urb *urb;
+               unsigned int iso_packets = usb_pipeisoc(channel->endpoint) ? channel->buf_size / channel->packet_size : 0;
 
-               if (usb_pipeisoc(channel->endpoint)) {
-                       /* don't expect iso out endpoints */
-                       iso_size = usb_maxpacket(instance->usb_dev, channel->endpoint, 0);
-                       iso_size -= iso_size % channel->stride; /* alignment */
-                       BUG_ON(!iso_size);
-                       iso_packets = (channel->buf_size - 1) / iso_size + 1;
-               }
+               UDSL_ASSERT(!usb_pipeisoc(channel->endpoint) || usb_pipein(channel->endpoint));
 
                urb = usb_alloc_urb(iso_packets, GFP_KERNEL);
                if (!urb) {
                        urb->transfer_flags = URB_ISO_ASAP;
                        urb->number_of_packets = iso_packets;
                        for (j = 0; j < iso_packets; j++) {
-                               urb->iso_frame_desc[j].offset = iso_size * j;
-                               urb->iso_frame_desc[j].length = min_t(int, iso_size,
-                                                                     channel->buf_size - urb->iso_frame_desc[j].offset);
+                               urb->iso_frame_desc[j].offset = channel->packet_size * j;
+                               urb->iso_frame_desc[j].length = channel->packet_size;
                        }
                }