diff --git a/src/devtools/adb_tcp/usb_linux.c b/src/devtools/adb_tcp/usb_linux.c
new file mode 100644
index 0000000..f16bdd0
--- /dev/null
+++ b/src/devtools/adb_tcp/usb_linux.c
@@ -0,0 +1,715 @@
+/*
+ * Copyright (C) 2007 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <ctype.h>
+
+#include <linux/usbdevice_fs.h>
+#include <linux/version.h>
+#if LINUX_VERSION_CODE > KERNEL_VERSION(2, 6, 20)
+#include <linux/usb/ch9.h>
+#else
+#include <linux/usb_ch9.h>
+#endif
+#include <asm/byteorder.h>
+
+#include "sysdeps.h"
+
+#define   TRACE_TAG  TRACE_USB
+#include "adb.h"
+
+
+/* usb scan debugging is waaaay too verbose */
+#define DBGX(x...)
+
+ADB_MUTEX_DEFINE( usb_lock );
+
+struct usb_handle
+{
+    usb_handle *prev;
+    usb_handle *next;
+
+    char fname[64];
+    int desc;
+    unsigned char ep_in;
+    unsigned char ep_out;
+
+    unsigned zero_mask;
+    unsigned writeable;
+
+    struct usbdevfs_urb urb_in;
+    struct usbdevfs_urb urb_out;
+
+    int urb_in_busy;
+    int urb_out_busy;
+    int dead;
+
+    adb_cond_t notify;
+    adb_mutex_t lock;
+
+    // for garbage collecting disconnected devices
+    int mark;
+
+    // ID of thread currently in REAPURB
+    pthread_t reaper_thread;
+};
+
+static usb_handle handle_list = {
+    .prev = &handle_list,
+    .next = &handle_list,
+};
+
+static int known_device(const char *dev_name)
+{
+    usb_handle *usb;
+
+    adb_mutex_lock(&usb_lock);
+    for(usb = handle_list.next; usb != &handle_list; usb = usb->next){
+        if(!strcmp(usb->fname, dev_name)) {
+            // set mark flag to indicate this device is still alive
+            usb->mark = 1;
+            adb_mutex_unlock(&usb_lock);
+            return 1;
+        }
+    }
+    adb_mutex_unlock(&usb_lock);
+    return 0;
+}
+
+static void kick_disconnected_devices()
+{
+    usb_handle *usb;
+
+    adb_mutex_lock(&usb_lock);
+    // kick any devices in the device list that were not found in the device scan
+    for(usb = handle_list.next; usb != &handle_list; usb = usb->next){
+        if (usb->mark == 0) {
+            usb_kick(usb);
+        } else {
+            usb->mark = 0;
+        }
+    }
+    adb_mutex_unlock(&usb_lock);
+
+}
+
+static void register_device(const char *dev_name, const char *devpath,
+                            unsigned char ep_in, unsigned char ep_out,
+                            int ifc, int serial_index, unsigned zero_mask);
+
+static inline int badname(const char *name)
+{
+    while(*name) {
+        if(!isdigit(*name++)) return 1;
+    }
+    return 0;
+}
+
+static void find_usb_device(const char *base,
+        void (*register_device_callback)
+                (const char *, const char *, unsigned char, unsigned char, int, int, unsigned))
+{
+    char busname[32], devname[32];
+    unsigned char local_ep_in, local_ep_out;
+    DIR *busdir , *devdir ;
+    struct dirent *de;
+    int fd ;
+
+    busdir = opendir(base);
+    if(busdir == 0) return;
+
+    while((de = readdir(busdir)) != 0) {
+        if(badname(de->d_name)) continue;
+
+        snprintf(busname, sizeof busname, "%s/%s", base, de->d_name);
+        devdir = opendir(busname);
+        if(devdir == 0) continue;
+
+//        DBGX("[ scanning %s ]\n", busname);
+        while((de = readdir(devdir))) {
+            unsigned char devdesc[4096];
+            unsigned char* bufptr = devdesc;
+            unsigned char* bufend;
+            struct usb_device_descriptor* device;
+            struct usb_config_descriptor* config;
+            struct usb_interface_descriptor* interface;
+            struct usb_endpoint_descriptor *ep1, *ep2;
+            unsigned zero_mask = 0;
+            unsigned vid, pid;
+            size_t desclength;
+
+            if(badname(de->d_name)) continue;
+            snprintf(devname, sizeof devname, "%s/%s", busname, de->d_name);
+
+            if(known_device(devname)) {
+                DBGX("skipping %s\n", devname);
+                continue;
+            }
+
+//            DBGX("[ scanning %s ]\n", devname);
+            if((fd = unix_open(devname, O_RDONLY | O_CLOEXEC)) < 0) {
+                continue;
+            }
+
+            desclength = adb_read(fd, devdesc, sizeof(devdesc));
+            bufend = bufptr + desclength;
+
+                // should have device and configuration descriptors, and atleast two endpoints
+            if (desclength < USB_DT_DEVICE_SIZE + USB_DT_CONFIG_SIZE) {
+                D("desclength %zu is too small\n", desclength);
+                adb_close(fd);
+                continue;
+            }
+
+            device = (struct usb_device_descriptor*)bufptr;
+            bufptr += USB_DT_DEVICE_SIZE;
+
+            if((device->bLength != USB_DT_DEVICE_SIZE) || (device->bDescriptorType != USB_DT_DEVICE)) {
+                adb_close(fd);
+                continue;
+            }
+
+            vid = device->idVendor;
+            pid = device->idProduct;
+            DBGX("[ %s is V:%04x P:%04x ]\n", devname, vid, pid);
+
+                // should have config descriptor next
+            config = (struct usb_config_descriptor *)bufptr;
+            bufptr += USB_DT_CONFIG_SIZE;
+            if (config->bLength != USB_DT_CONFIG_SIZE || config->bDescriptorType != USB_DT_CONFIG) {
+                D("usb_config_descriptor not found\n");
+                adb_close(fd);
+                continue;
+            }
+
+                // loop through all the descriptors and look for the ADB interface
+            while (bufptr < bufend) {
+                unsigned char length = bufptr[0];
+                unsigned char type = bufptr[1];
+
+                if (type == USB_DT_INTERFACE) {
+                    interface = (struct usb_interface_descriptor *)bufptr;
+                    bufptr += length;
+
+                    if (length != USB_DT_INTERFACE_SIZE) {
+                        D("interface descriptor has wrong size\n");
+                        break;
+                    }
+
+                    DBGX("bInterfaceClass: %d,  bInterfaceSubClass: %d,"
+                         "bInterfaceProtocol: %d, bNumEndpoints: %d\n",
+                         interface->bInterfaceClass, interface->bInterfaceSubClass,
+                         interface->bInterfaceProtocol, interface->bNumEndpoints);
+
+                    if (interface->bNumEndpoints == 2 &&
+                            is_adb_interface(vid, pid, interface->bInterfaceClass,
+                            interface->bInterfaceSubClass, interface->bInterfaceProtocol))  {
+
+                        struct stat st;
+                        char pathbuf[128];
+                        char link[256];
+                        char *devpath = NULL;
+
+                        DBGX("looking for bulk endpoints\n");
+                            // looks like ADB...
+                        ep1 = (struct usb_endpoint_descriptor *)bufptr;
+                        bufptr += USB_DT_ENDPOINT_SIZE;
+                        ep2 = (struct usb_endpoint_descriptor *)bufptr;
+                        bufptr += USB_DT_ENDPOINT_SIZE;
+
+                        if (bufptr > devdesc + desclength ||
+                            ep1->bLength != USB_DT_ENDPOINT_SIZE ||
+                            ep1->bDescriptorType != USB_DT_ENDPOINT ||
+                            ep2->bLength != USB_DT_ENDPOINT_SIZE ||
+                            ep2->bDescriptorType != USB_DT_ENDPOINT) {
+                            D("endpoints not found\n");
+                            break;
+                        }
+
+                            // both endpoints should be bulk
+                        if (ep1->bmAttributes != USB_ENDPOINT_XFER_BULK ||
+                            ep2->bmAttributes != USB_ENDPOINT_XFER_BULK) {
+                            D("bulk endpoints not found\n");
+                            continue;
+                        }
+                            /* aproto 01 needs 0 termination */
+                        if(interface->bInterfaceProtocol == 0x01) {
+                            zero_mask = ep1->wMaxPacketSize - 1;
+                        }
+
+                            // we have a match.  now we just need to figure out which is in and which is out.
+                        if (ep1->bEndpointAddress & USB_ENDPOINT_DIR_MASK) {
+                            local_ep_in = ep1->bEndpointAddress;
+                            local_ep_out = ep2->bEndpointAddress;
+                        } else {
+                            local_ep_in = ep2->bEndpointAddress;
+                            local_ep_out = ep1->bEndpointAddress;
+                        }
+
+                            // Determine the device path
+                        if (!fstat(fd, &st) && S_ISCHR(st.st_mode)) {
+                            char *slash;
+                            ssize_t link_len;
+                            snprintf(pathbuf, sizeof(pathbuf), "/sys/dev/char/%d:%d",
+                                     major(st.st_rdev), minor(st.st_rdev));
+                            link_len = readlink(pathbuf, link, sizeof(link) - 1);
+                            if (link_len > 0) {
+                                link[link_len] = '\0';
+                                slash = strrchr(link, '/');
+                                if (slash) {
+                                    snprintf(pathbuf, sizeof(pathbuf),
+                                             "usb:%s", slash + 1);
+                                    devpath = pathbuf;
+                                }
+                            }
+                        }
+
+                        register_device_callback(devname, devpath,
+                                local_ep_in, local_ep_out,
+                                interface->bInterfaceNumber, device->iSerialNumber, zero_mask);
+                        break;
+                    }
+                } else {
+                    bufptr += length;
+                }
+            } // end of while
+
+            adb_close(fd);
+        } // end of devdir while
+        closedir(devdir);
+    } //end of busdir while
+    closedir(busdir);
+}
+
+void usb_cleanup()
+{
+}
+
+static int usb_bulk_write(usb_handle *h, const void *data, int len)
+{
+    struct usbdevfs_urb *urb = &h->urb_out;
+    int res;
+    struct timeval tv;
+    struct timespec ts;
+
+    memset(urb, 0, sizeof(*urb));
+    urb->type = USBDEVFS_URB_TYPE_BULK;
+    urb->endpoint = h->ep_out;
+    urb->status = -1;
+    urb->buffer = (void*) data;
+    urb->buffer_length = len;
+
+    D("++ write ++\n");
+
+    adb_mutex_lock(&h->lock);
+    if(h->dead) {
+        res = -1;
+        goto fail;
+    }
+    do {
+        res = ioctl(h->desc, USBDEVFS_SUBMITURB, urb);
+    } while((res < 0) && (errno == EINTR));
+
+    if(res < 0) {
+        goto fail;
+    }
+
+    res = -1;
+    h->urb_out_busy = 1;
+    for(;;) {
+        /* time out after five seconds */
+        gettimeofday(&tv, NULL);
+        ts.tv_sec = tv.tv_sec + 5;
+        ts.tv_nsec = tv.tv_usec * 1000L;
+        res = pthread_cond_timedwait(&h->notify, &h->lock, &ts);
+        if(res < 0 || h->dead) {
+            break;
+        }
+        if(h->urb_out_busy == 0) {
+            if(urb->status == 0) {
+                res = urb->actual_length;
+            }
+            break;
+        }
+    }
+fail:
+    adb_mutex_unlock(&h->lock);
+    D("-- write --\n");
+    return res;
+}
+
+static int usb_bulk_read(usb_handle *h, void *data, int len)
+{
+    struct usbdevfs_urb *urb = &h->urb_in;
+    struct usbdevfs_urb *out = NULL;
+    int res;
+
+    memset(urb, 0, sizeof(*urb));
+    urb->type = USBDEVFS_URB_TYPE_BULK;
+    urb->endpoint = h->ep_in;
+    urb->status = -1;
+    urb->buffer = data;
+    urb->buffer_length = len;
+
+
+    adb_mutex_lock(&h->lock);
+    if(h->dead) {
+        res = -1;
+        goto fail;
+    }
+    do {
+        res = ioctl(h->desc, USBDEVFS_SUBMITURB, urb);
+    } while((res < 0) && (errno == EINTR));
+
+    if(res < 0) {
+        goto fail;
+    }
+
+    h->urb_in_busy = 1;
+    for(;;) {
+        D("[ reap urb - wait ]\n");
+        h->reaper_thread = pthread_self();
+        adb_mutex_unlock(&h->lock);
+        res = ioctl(h->desc, USBDEVFS_REAPURB, &out);
+        int saved_errno = errno;
+        adb_mutex_lock(&h->lock);
+        h->reaper_thread = 0;
+        if(h->dead) {
+            res = -1;
+            break;
+        }
+        if(res < 0) {
+            if(saved_errno == EINTR) {
+                continue;
+            }
+            D("[ reap urb - error ]\n");
+            break;
+        }
+        D("[ urb @%p status = %d, actual = %d ]\n",
+            out, out->status, out->actual_length);
+
+        if(out == &h->urb_in) {
+            D("[ reap urb - IN complete ]\n");
+            h->urb_in_busy = 0;
+            if(urb->status == 0) {
+                res = urb->actual_length;
+            } else {
+                res = -1;
+            }
+            break;
+        }
+        if(out == &h->urb_out) {
+            D("[ reap urb - OUT compelete ]\n");
+            h->urb_out_busy = 0;
+            adb_cond_broadcast(&h->notify);
+        }
+    }
+fail:
+    adb_mutex_unlock(&h->lock);
+    return res;
+}
+
+
+int usb_write(usb_handle *h, const void *_data, int len)
+{
+    unsigned char *data = (unsigned char*) _data;
+    int n;
+    int need_zero = 0;
+
+    if(h->zero_mask) {
+            /* if we need 0-markers and our transfer
+            ** is an even multiple of the packet size,
+            ** we make note of it
+            */
+        if(!(len & h->zero_mask)) {
+            need_zero = 1;
+        }
+    }
+
+    while(len > 0) {
+        int xfer = (len > 4096) ? 4096 : len;
+
+        n = usb_bulk_write(h, data, xfer);
+        if(n != xfer) {
+            D("ERROR: n = %d, errno = %d (%s)\n",
+                n, errno, strerror(errno));
+            return -1;
+        }
+
+        len -= xfer;
+        data += xfer;
+    }
+
+    if(need_zero){
+        n = usb_bulk_write(h, _data, 0);
+        return n;
+    }
+
+    return 0;
+}
+
+int usb_read(usb_handle *h, void *_data, int len)
+{
+    unsigned char *data = (unsigned char*) _data;
+    int n;
+
+    D("++ usb_read ++\n");
+    while(len > 0) {
+        int xfer = (len > 4096) ? 4096 : len;
+
+        D("[ usb read %d fd = %d], fname=%s\n", xfer, h->desc, h->fname);
+        n = usb_bulk_read(h, data, xfer);
+        D("[ usb read %d ] = %d, fname=%s\n", xfer, n, h->fname);
+        if(n != xfer) {
+            if((errno == ETIMEDOUT) && (h->desc != -1)) {
+                D("[ timeout ]\n");
+                if(n > 0){
+                    data += n;
+                    len -= n;
+                }
+                continue;
+            }
+            D("ERROR: n = %d, errno = %d (%s)\n",
+                n, errno, strerror(errno));
+            return -1;
+        }
+
+        len -= xfer;
+        data += xfer;
+    }
+
+    D("-- usb_read --\n");
+    return 0;
+}
+
+void usb_kick(usb_handle *h)
+{
+    D("[ kicking %p (fd = %d) ]\n", h, h->desc);
+    adb_mutex_lock(&h->lock);
+    if(h->dead == 0) {
+        h->dead = 1;
+
+        if (h->writeable) {
+            /* HACK ALERT!
+            ** Sometimes we get stuck in ioctl(USBDEVFS_REAPURB).
+            ** This is a workaround for that problem.
+            */
+            if (h->reaper_thread) {
+                pthread_kill(h->reaper_thread, SIGALRM);
+            }
+
+            /* cancel any pending transactions
+            ** these will quietly fail if the txns are not active,
+            ** but this ensures that a reader blocked on REAPURB
+            ** will get unblocked
+            */
+            ioctl(h->desc, USBDEVFS_DISCARDURB, &h->urb_in);
+            ioctl(h->desc, USBDEVFS_DISCARDURB, &h->urb_out);
+            h->urb_in.status = -ENODEV;
+            h->urb_out.status = -ENODEV;
+            h->urb_in_busy = 0;
+            h->urb_out_busy = 0;
+            adb_cond_broadcast(&h->notify);
+        } else {
+            unregister_usb_transport(h);
+        }
+    }
+    adb_mutex_unlock(&h->lock);
+}
+
+int usb_close(usb_handle *h)
+{
+    D("[ usb close ... ]\n");
+    adb_mutex_lock(&usb_lock);
+    h->next->prev = h->prev;
+    h->prev->next = h->next;
+    h->prev = 0;
+    h->next = 0;
+
+    adb_close(h->desc);
+    D("[ usb closed %p (fd = %d) ]\n", h, h->desc);
+    adb_mutex_unlock(&usb_lock);
+
+    free(h);
+    return 0;
+}
+
+static void register_device(const char *dev_name, const char *devpath,
+                            unsigned char ep_in, unsigned char ep_out,
+                            int interface, int serial_index, unsigned zero_mask)
+{
+    usb_handle* usb = 0;
+    int n = 0;
+    char serial[256];
+
+        /* Since Linux will not reassign the device ID (and dev_name)
+        ** as long as the device is open, we can add to the list here
+        ** once we open it and remove from the list when we're finally
+        ** closed and everything will work out fine.
+        **
+        ** If we have a usb_handle on the list 'o handles with a matching
+        ** name, we have no further work to do.
+        */
+    adb_mutex_lock(&usb_lock);
+    for(usb = handle_list.next; usb != &handle_list; usb = usb->next){
+        if(!strcmp(usb->fname, dev_name)) {
+            adb_mutex_unlock(&usb_lock);
+            return;
+        }
+    }
+    adb_mutex_unlock(&usb_lock);
+
+    D("[ usb located new device %s (%d/%d/%d) ]\n",
+        dev_name, ep_in, ep_out, interface);
+    usb = calloc(1, sizeof(usb_handle));
+    strcpy(usb->fname, dev_name);
+    usb->ep_in = ep_in;
+    usb->ep_out = ep_out;
+    usb->zero_mask = zero_mask;
+    usb->writeable = 1;
+
+    adb_cond_init(&usb->notify, 0);
+    adb_mutex_init(&usb->lock, 0);
+    /* initialize mark to 1 so we don't get garbage collected after the device scan */
+    usb->mark = 1;
+    usb->reaper_thread = 0;
+
+    usb->desc = unix_open(usb->fname, O_RDWR | O_CLOEXEC);
+    if(usb->desc < 0) {
+        /* if we fail, see if have read-only access */
+        usb->desc = unix_open(usb->fname, O_RDONLY | O_CLOEXEC);
+        if(usb->desc < 0) goto fail;
+        usb->writeable = 0;
+        D("[ usb open read-only %s fd = %d]\n", usb->fname, usb->desc);
+    } else {
+        D("[ usb open %s fd = %d]\n", usb->fname, usb->desc);
+        n = ioctl(usb->desc, USBDEVFS_CLAIMINTERFACE, &interface);
+        if(n != 0) goto fail;
+    }
+
+        /* read the device's serial number */
+    serial[0] = 0;
+    memset(serial, 0, sizeof(serial));
+    if (serial_index) {
+        struct usbdevfs_ctrltransfer  ctrl;
+        __u16 buffer[128];
+        __u16 languages[128];
+        int i, result;
+        int languageCount = 0;
+
+        memset(languages, 0, sizeof(languages));
+        memset(&ctrl, 0, sizeof(ctrl));
+
+            // read list of supported languages
+        ctrl.bRequestType = USB_DIR_IN|USB_TYPE_STANDARD|USB_RECIP_DEVICE;
+        ctrl.bRequest = USB_REQ_GET_DESCRIPTOR;
+        ctrl.wValue = (USB_DT_STRING << 8) | 0;
+        ctrl.wIndex = 0;
+        ctrl.wLength = sizeof(languages);
+        ctrl.data = languages;
+        ctrl.timeout = 1000;
+
+        result = ioctl(usb->desc, USBDEVFS_CONTROL, &ctrl);
+        if (result > 0)
+            languageCount = (result - 2) / 2;
+
+        for (i = 1; i <= languageCount; i++) {
+            memset(buffer, 0, sizeof(buffer));
+            memset(&ctrl, 0, sizeof(ctrl));
+
+            ctrl.bRequestType = USB_DIR_IN|USB_TYPE_STANDARD|USB_RECIP_DEVICE;
+            ctrl.bRequest = USB_REQ_GET_DESCRIPTOR;
+            ctrl.wValue = (USB_DT_STRING << 8) | serial_index;
+            ctrl.wIndex = __le16_to_cpu(languages[i]);
+            ctrl.wLength = sizeof(buffer);
+            ctrl.data = buffer;
+            ctrl.timeout = 1000;
+
+            result = ioctl(usb->desc, USBDEVFS_CONTROL, &ctrl);
+            if (result > 0) {
+                int i;
+                // skip first word, and copy the rest to the serial string, changing shorts to bytes.
+                result /= 2;
+                for (i = 1; i < result; i++)
+                    serial[i - 1] = __le16_to_cpu(buffer[i]);
+                serial[i - 1] = 0;
+                break;
+            }
+        }
+    }
+
+        /* add to the end of the active handles */
+    adb_mutex_lock(&usb_lock);
+    usb->next = &handle_list;
+    usb->prev = handle_list.prev;
+    usb->prev->next = usb;
+    usb->next->prev = usb;
+    adb_mutex_unlock(&usb_lock);
+
+    register_usb_transport(usb, serial, devpath, usb->writeable);
+    return;
+
+fail:
+    D("[ usb open %s error=%d, err_str = %s]\n",
+        usb->fname,  errno, strerror(errno));
+    if(usb->desc >= 0) {
+        adb_close(usb->desc);
+    }
+    free(usb);
+}
+
+void* device_poll_thread(void* unused)
+{
+    D("Created device thread\n");
+    for(;;) {
+            /* XXX use inotify */
+        find_usb_device("/dev/bus/usb", register_device);
+        kick_disconnected_devices();
+        sleep(1);
+    }
+    return NULL;
+}
+
+static void sigalrm_handler(int signo)
+{
+    // don't need to do anything here
+}
+
+void usb_init()
+{
+    adb_thread_t tid;
+    struct sigaction    actions;
+
+    memset(&actions, 0, sizeof(actions));
+    sigemptyset(&actions.sa_mask);
+    actions.sa_flags = 0;
+    actions.sa_handler = sigalrm_handler;
+    sigaction(SIGALRM,& actions, NULL);
+
+    if(adb_thread_create(&tid, device_poll_thread, NULL)){
+        fatal_errno("cannot create input thread");
+    }
+}