[Feauture] support adbd listening on tcp port with uci config

Change-Id: Ic885b955900cf3cf20322ba5f54ff47d1eedf0ef
diff --git a/src/devtools/adb_tcp/usb_linux_client.c b/src/devtools/adb_tcp/usb_linux_client.c
new file mode 100644
index 0000000..2466275
--- /dev/null
+++ b/src/devtools/adb_tcp/usb_linux_client.c
@@ -0,0 +1,744 @@
+/*
+ * 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 <linux/usb/ch9.h>
+#include <linux/usb/functionfs.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <errno.h>
+#include <stddef.h>
+#include <sys/epoll.h>
+
+#include "sysdeps.h"
+
+#define   TRACE_TAG  TRACE_USB
+#include "adb.h"
+
+#define MAX_PACKET_SIZE_FS	64
+#define MAX_PACKET_SIZE_HS	512
+#define MAX_PACKET_SIZE_SS	1024
+
+//#define cpu_to_le16(x)  htole16(x)
+//#define cpu_to_le32(x)  htole32(x)
+/*
+ * cpu_to_le16/32 are used when initializing structures, a context where a
+ * function call is not allowed. To solve this, we code cpu_to_le16/32 in a way
+ * that allows them to be used when initializing structures.
+ */
+
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+#define cpu_to_le16(x)  (x)
+#define cpu_to_le32(x)  (x)
+#else
+#define cpu_to_le16(x)  ((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8))
+#define cpu_to_le32(x)  \
+    ((((x) & 0xff000000u) >> 24) | (((x) & 0x00ff0000u) >>  8) | \
+    (((x) & 0x0000ff00u) <<  8) | (((x) & 0x000000ffu) << 24))
+#endif
+
+#define FFS_CONTOL_MAX_EPOLL_EVENT 50
+#define DEBUG   0
+
+struct usb_handle
+{
+    adb_cond_t notify;
+    adb_mutex_t lock;
+
+    int (*write)(usb_handle *h, const void *data, int len);
+    int (*read)(usb_handle *h, void *data, int len);
+    void (*kick)(usb_handle *h);
+
+    // Legacy f_adb
+    int fd;
+
+    // FunctionFS
+    int control;
+    int bulk_out; /* "out" from the host's perspective => source for adbd */
+    int bulk_in;  /* "in" from the host's perspective => sink for adbd */
+    bool ffs_control_thread_created;
+};
+
+static const struct {
+    __le32 magic;
+    __le32 length;
+    __le32 flags;
+    __le32 fs_count;
+    __le32 hs_count;
+    __le32 ss_count;
+    struct {
+        struct usb_interface_descriptor intf;
+        struct usb_endpoint_descriptor_no_audio source;
+        struct usb_endpoint_descriptor_no_audio sink;
+    } __attribute__((packed)) fs_descs, hs_descs;
+    struct {
+        struct usb_interface_descriptor intf;
+        struct usb_endpoint_descriptor_no_audio source;
+        struct usb_ss_ep_comp_descriptor source_comp;
+        struct usb_endpoint_descriptor_no_audio sink;
+        struct usb_ss_ep_comp_descriptor sink_comp;
+    } __attribute__((packed)) ss_descs;
+} __attribute__((packed)) descriptors = {
+    .magic = cpu_to_le32(FUNCTIONFS_DESCRIPTORS_MAGIC_V2),
+    .length = cpu_to_le32(sizeof(descriptors)),
+    .flags = cpu_to_le32(FUNCTIONFS_HAS_FS_DESC |
+                         FUNCTIONFS_HAS_HS_DESC |
+                         FUNCTIONFS_HAS_SS_DESC),
+    .fs_count = 3,
+    .hs_count = 3,
+    .ss_count = 5,
+    .fs_descs = {
+        .intf = {
+            .bLength = sizeof(descriptors.fs_descs.intf),
+            .bDescriptorType = USB_DT_INTERFACE,
+            .bInterfaceNumber = 0,
+            .bNumEndpoints = 2,
+            .bInterfaceClass = ADB_CLASS,
+            .bInterfaceSubClass = ADB_SUBCLASS,
+            .bInterfaceProtocol = ADB_PROTOCOL,
+            .iInterface = 1, /* first string from the provided table */
+        },
+        .source = {
+            .bLength = sizeof(descriptors.fs_descs.source),
+            .bDescriptorType = USB_DT_ENDPOINT,
+            .bEndpointAddress = 1 | USB_DIR_OUT,
+            .bmAttributes = USB_ENDPOINT_XFER_BULK,
+            .wMaxPacketSize = MAX_PACKET_SIZE_FS,
+        },
+        .sink = {
+            .bLength = sizeof(descriptors.fs_descs.sink),
+            .bDescriptorType = USB_DT_ENDPOINT,
+            .bEndpointAddress = 2 | USB_DIR_IN,
+            .bmAttributes = USB_ENDPOINT_XFER_BULK,
+            .wMaxPacketSize = MAX_PACKET_SIZE_FS,
+        },
+    },
+    .hs_descs = {
+        .intf = {
+            .bLength = sizeof(descriptors.hs_descs.intf),
+            .bDescriptorType = USB_DT_INTERFACE,
+            .bInterfaceNumber = 0,
+            .bNumEndpoints = 2,
+            .bInterfaceClass = ADB_CLASS,
+            .bInterfaceSubClass = ADB_SUBCLASS,
+            .bInterfaceProtocol = ADB_PROTOCOL,
+            .iInterface = 1, /* first string from the provided table */
+        },
+        .source = {
+            .bLength = sizeof(descriptors.hs_descs.source),
+            .bDescriptorType = USB_DT_ENDPOINT,
+            .bEndpointAddress = 1 | USB_DIR_OUT,
+            .bmAttributes = USB_ENDPOINT_XFER_BULK,
+            .wMaxPacketSize = MAX_PACKET_SIZE_HS,
+        },
+        .sink = {
+            .bLength = sizeof(descriptors.hs_descs.sink),
+            .bDescriptorType = USB_DT_ENDPOINT,
+            .bEndpointAddress = 2 | USB_DIR_IN,
+            .bmAttributes = USB_ENDPOINT_XFER_BULK,
+            .wMaxPacketSize = MAX_PACKET_SIZE_HS,
+        },
+    },
+    .ss_descs = {
+        .intf = {
+            .bLength = sizeof(descriptors.ss_descs.intf),
+            .bDescriptorType = USB_DT_INTERFACE,
+            .bInterfaceNumber = 0,
+            .bNumEndpoints = 2,
+            .bInterfaceClass = ADB_CLASS,
+            .bInterfaceSubClass = ADB_SUBCLASS,
+            .bInterfaceProtocol = ADB_PROTOCOL,
+            .iInterface = 1, /* first string from the provided table */
+        },
+        .source = {
+            .bLength = sizeof(descriptors.ss_descs.source),
+            .bDescriptorType = USB_DT_ENDPOINT,
+            .bEndpointAddress = 1 | USB_DIR_OUT,
+            .bmAttributes = USB_ENDPOINT_XFER_BULK,
+            .wMaxPacketSize = MAX_PACKET_SIZE_SS,
+        },
+        .source_comp = {
+            .bLength = sizeof(descriptors.ss_descs.source_comp),
+            .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
+        },
+        .sink = {
+            .bLength = sizeof(descriptors.ss_descs.sink),
+            .bDescriptorType = USB_DT_ENDPOINT,
+            .bEndpointAddress = 2 | USB_DIR_IN,
+            .bmAttributes = USB_ENDPOINT_XFER_BULK,
+            .wMaxPacketSize = MAX_PACKET_SIZE_SS,
+        },
+        .sink_comp = {
+            .bLength = sizeof(descriptors.ss_descs.sink_comp),
+            .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
+        },
+    },
+};
+
+#define STR_INTERFACE_ "ADB Interface"
+
+static const struct {
+    struct usb_functionfs_strings_head header;
+    struct {
+        __le16 code;
+        const char str1[sizeof(STR_INTERFACE_)];
+    } __attribute__((packed)) lang0;
+} __attribute__((packed)) strings = {
+    .header = {
+        .magic = cpu_to_le32(FUNCTIONFS_STRINGS_MAGIC),
+        .length = cpu_to_le32(sizeof(strings)),
+        .str_count = cpu_to_le32(1),
+        .lang_count = cpu_to_le32(1),
+    },
+    .lang0 = {
+        cpu_to_le16(0x0409), /* en-us */
+        STR_INTERFACE_,
+    },
+};
+
+static void *usb_adb_open_thread(void *x)
+{
+    struct usb_handle *usb = (struct usb_handle *)x;
+    int fd;
+
+    while (1) {
+        // wait until the USB device needs opening
+        adb_mutex_lock(&usb->lock);
+        while (usb->fd != -1)
+            adb_cond_wait(&usb->notify, &usb->lock);
+        adb_mutex_unlock(&usb->lock);
+
+        D("[ usb_thread - opening device ]\n");
+        do {
+            /* XXX use inotify? */
+            fd = unix_open("/dev/android_adb", O_RDWR);
+            if (fd < 0) {
+                // to support older kernels
+                fd = unix_open("/dev/android", O_RDWR);
+            }
+            if (fd < 0) {
+                adb_sleep_ms(1000);
+            }
+        } while (fd < 0);
+        D("[ opening device succeeded ]\n");
+
+        close_on_exec(fd);
+        usb->fd = fd;
+
+        D("[ usb_thread - registering device ]\n");
+        register_usb_transport(usb, 0, 0, 1);
+    }
+
+    // never gets here
+    return 0;
+}
+
+static int usb_adb_write(usb_handle *h, const void *data, int len)
+{
+    int n;
+
+    D("about to write (fd=%d, len=%d)\n", h->fd, len);
+    n = adb_write(h->fd, data, len);
+    if(n != len) {
+        D("ERROR: fd = %d, n = %d, errno = %d (%s)\n",
+            h->fd, n, errno, strerror(errno));
+        return -1;
+    }
+    D("[ done fd=%d ]\n", h->fd);
+    return 0;
+}
+
+static int usb_adb_read(usb_handle *h, void *data, int len)
+{
+    int n;
+
+    D("about to read (fd=%d, len=%d)\n", h->fd, len);
+    n = adb_read(h->fd, data, len);
+    if(n != len) {
+        D("ERROR: fd = %d, n = %d, errno = %d (%s)\n",
+            h->fd, n, errno, strerror(errno));
+        return -1;
+    }
+    D("[ done fd=%d ]\n", h->fd);
+    return 0;
+}
+
+static void usb_adb_kick(usb_handle *h)
+{
+    D("usb_kick\n");
+    adb_mutex_lock(&h->lock);
+    adb_close(h->fd);
+    h->fd = -1;
+
+    // notify usb_adb_open_thread that we are disconnected
+    adb_cond_signal(&h->notify);
+    adb_mutex_unlock(&h->lock);
+}
+
+static void usb_adb_init()
+{
+    usb_handle *h;
+    adb_thread_t tid;
+    int fd;
+
+    h = calloc(1, sizeof(usb_handle));
+    if (h == 0) {
+        fatal("cannot allocate usb_handle");
+        return;
+    }
+
+    h->write = usb_adb_write;
+    h->read = usb_adb_read;
+    h->kick = usb_adb_kick;
+    h->bulk_in = -1;
+    h->bulk_out = -1;
+    h->control = -1;
+    h->ffs_control_thread_created = false;
+    h->fd = -1;
+
+    adb_cond_init(&h->notify, 0);
+    adb_mutex_init(&h->lock, 0);
+
+    // Open the file /dev/android_adb_enable to trigger
+    // the enabling of the adb USB function in the kernel.
+    // We never touch this file again - just leave it open
+    // indefinitely so the kernel will know when we are running
+    // and when we are not.
+    fd = unix_open("/dev/android_adb_enable", O_RDWR);
+    if (fd < 0) {
+       D("failed to open /dev/android_adb_enable\n");
+    } else {
+        close_on_exec(fd);
+    }
+
+    D("[ usb_init - starting thread ]\n");
+    if(adb_thread_create(&tid, usb_adb_open_thread, h)){
+        fatal_errno("cannot create usb thread");
+    }
+}
+
+static void *ffs_control_read_msg_thread(void *_h)
+{
+    usb_handle *h = _h;
+    int fd = h->control;
+
+    char buf[MAX_PACKET_SIZE_FS];
+    int size = 0;//event.u.setup.wLength;
+    if (DEBUG) D("FUNCTIONFS_SETUP acking host-to-device control transfer size=%d", size);
+    if (size+1 > MAX_PACKET_SIZE_FS) {
+        D("package size larger than MAX_PACKET_SIZE_FS");
+        return 0;
+    }
+
+    if (DEBUG) D("FUNCTIONFS_SETUP before get host-to-device msg size:%d", size);
+    int rc = adb_read(fd, buf, size);
+    if (DEBUG) D("FUNCTIONFS_SETUP after get host-to-device msg rc:%d", rc);
+    if (rc != size) {
+        D("Read %d bytes when trying to read control request, expected %d", rc, size);
+    }
+    return 0;
+}
+
+static char* ffs_get_event_type_code(int type) {
+    char* code;
+    switch(type) {
+        case FUNCTIONFS_BIND:
+            code = "BIND";
+            break;
+        case FUNCTIONFS_UNBIND:
+            code = "UNBIND";
+            break;
+        case FUNCTIONFS_ENABLE:
+            code = "ENABLE";
+            break;
+        case FUNCTIONFS_DISABLE:
+            code = "DISABLE";
+            break;
+        case FUNCTIONFS_SETUP:
+            code = "SETUP";
+            break;
+        case FUNCTIONFS_SUSPEND:
+            code = "SUSPEND";
+            break;
+        case FUNCTIONFS_RESUME:
+            code = "RESUME";
+            break;
+        default:
+            code = "UNKNOWN";
+            break;
+        }
+    return code;
+}
+
+static void ffs_control_event_handler(usb_handle *h) {
+    int fd = h->control;
+    struct usb_functionfs_event event;
+    int ret = 0;
+
+    if (DEBUG) D("start remote usb read control fd:%d size=%d\n", fd, (int)sizeof(event));
+    ret = adb_read(fd, &event, sizeof(event));
+    if (DEBUG) D("done remote usb read control ret=%d size=%d\n", ret, (int)sizeof(event));
+    if (ret != sizeof(event)) {
+        if (DEBUG) D("remote usb: read size:%d not expect to event size:%d\n", ret, (int)sizeof(event));
+        return;
+    }
+
+    D("event.type: %s\n", ffs_get_event_type_code(event.type));
+
+    switch (event.type) {
+        case FUNCTIONFS_SETUP: {
+            D("received FUNCTIONFS_SETUP");
+            D("bRequestType = %d",(int)(event.u.setup.bRequestType));
+            D("bRequest = %d\n", (int)(event.u.setup.bRequest));
+            D("wValue = %d\n", (int)(event.u.setup.wValue));
+            D("wIndex = %d\n", (int)(event.u.setup.wIndex));
+            D("wLength = %d\n", (int)(event.u.setup.wLength));
+
+            if ((event.u.setup.bRequestType & USB_DIR_IN)) {
+                if (DEBUG) D("FUNCTIONFS_SETUP acking device-to-host control transfer");
+                int rc = adb_write(fd, "", 0);
+                if (rc != 0) {
+                    D("Failed to write empty packet to host");
+                    break;
+                }
+            } else {
+                adb_thread_t ffs_control_read_msg_thread_ptr;
+
+                if(adb_thread_create(&ffs_control_read_msg_thread_ptr, ffs_control_read_msg_thread, h)) {
+                    fatal_errno("cannot create control thread");
+                }
+
+
+                if (DEBUG) D("Wait 100ms before kill read msg thread");
+                adb_sleep_ms(100);
+                int ret = pthread_cancel(ffs_control_read_msg_thread_ptr);
+                D("Done kill the read msg thread ret=%d", ret);
+            }
+        }
+    }
+}
+
+// -1 means failure
+static int epoll_add_fd(int epfd, int fd) {
+    struct epoll_event ev;
+    memset(&ev, 0, sizeof(ev));
+    ev.data.fd = fd;
+    ev.events = EPOLLIN;
+    // don't set the fd to edge trigger
+    // the some event like accept may be lost if two or more clients are connecting to server at the same time
+    // level trigger is preferred to avoid event lost
+    // do not set EPOLLOUT due to it will always trigger when write is available
+    if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd, &ev) == -1) {
+        D("epoll_add_fd3() epoll_ctl() failed reason=[%s]%d epfd=%d fd=%d",
+            strerror(errno), errno, epfd, fd);
+        return -1;
+    }
+    return 0;
+}
+
+static void *ffs_control_thread(void *_h)
+{
+    usb_handle *h = _h;
+    int control_fd = h->control;
+    struct epoll_event events[FFS_CONTOL_MAX_EPOLL_EVENT];
+
+    int epfd = epoll_create(FFS_CONTOL_MAX_EPOLL_EVENT);
+    if(epfd == -1) {
+        D("ERR: epoll_create() fail reason=[%s]", strerror(errno));
+        return 0;
+    }
+
+    epoll_add_fd(epfd, control_fd);
+
+    while(1) {
+        int i;
+        int n;
+
+        D("Before ffs control thread epoll_wait");
+        n = epoll_wait(epfd, events, FFS_CONTOL_MAX_EPOLL_EVENT , -1);
+
+        for(i = 0; i < n; i++) {
+            if(events[i].data.fd == control_fd) {
+                if(events[i].events & EPOLLIN) {
+                    if (DEBUG) D("control_fd event triggered");
+                    ffs_control_event_handler(h);
+                }
+            }
+        }
+    }
+}
+
+void ffs_create_control_thread(usb_handle *h) {
+    if (h->control >= 0) {  // only for ffs usb
+        if (!h->ffs_control_thread_created) {
+            adb_thread_t ffs_control_thread_ptr;
+
+            if(adb_thread_create(&ffs_control_thread_ptr, ffs_control_thread, h)){
+                fatal_errno("cannot create ffs_control_thread");
+            } else {
+                h->ffs_control_thread_created = true;
+                if (DEBUG) D("Created ffs_control_thread success");
+            }
+        }
+    }
+}
+
+static void init_functionfs(struct usb_handle *h)
+{
+    ssize_t ret;
+
+    if (h->control < 0) { // might have already done this before
+        D("OPENING %s\n", USB_FFS_ADB_EP0);
+        h->control = adb_open(USB_FFS_ADB_EP0, O_RDWR);
+        if (h->control < 0) {
+            D("[ %s: cannot open control endpoint: errno=%d]\n", USB_FFS_ADB_EP0, errno);
+            goto err;
+        }
+
+        ret = adb_write(h->control, &descriptors, sizeof(descriptors));
+        if (ret < 0) {
+            D("[ %s: write descriptors failed: errno=%d ]\n", USB_FFS_ADB_EP0, errno);
+            goto err;
+        }
+
+        ret = adb_write(h->control, &strings, sizeof(strings));
+        if (ret < 0) {
+            D("[ %s: writing strings failed: errno=%d]\n", USB_FFS_ADB_EP0, errno);
+            goto err;
+        }
+    }
+
+    h->bulk_out = adb_open(USB_FFS_ADB_OUT, O_RDWR);
+    if (h->bulk_out < 0) {
+        D("[ %s: cannot open bulk-out ep: errno=%d ]\n", USB_FFS_ADB_OUT, errno);
+        goto err;
+    }
+
+    h->bulk_in = adb_open(USB_FFS_ADB_IN, O_RDWR);
+    if (h->bulk_in < 0) {
+        D("[ %s: cannot open bulk-in ep: errno=%d ]\n", USB_FFS_ADB_IN, errno);
+        goto err;
+    }
+
+    ffs_create_control_thread(h);
+    return;
+
+err:
+    if (h->bulk_in > 0) {
+        adb_close(h->bulk_in);
+        h->bulk_in = -1;
+    }
+    if (h->bulk_out > 0) {
+        adb_close(h->bulk_out);
+        h->bulk_out = -1;
+    }
+    if (h->control > 0) {
+        adb_close(h->control);
+        h->control = -1;
+    }
+    return;
+}
+
+static void *usb_ffs_open_thread(void *x)
+{
+    struct usb_handle *usb = (struct usb_handle *)x;
+
+    while (1) {
+        // wait until the USB device needs opening
+        adb_mutex_lock(&usb->lock);
+        while (usb->control != -1 && usb->bulk_in != -1 && usb->bulk_out != -1)
+            adb_cond_wait(&usb->notify, &usb->lock);
+        adb_mutex_unlock(&usb->lock);
+
+        while (1) {
+            init_functionfs(usb);
+
+            if (usb->control >= 0 && usb->bulk_in >= 0 && usb->bulk_out >= 0)
+                break;
+
+            adb_sleep_ms(1000);
+        }
+
+        D("[ usb_thread - registering device ]\n");
+        register_usb_transport(usb, 0, 0, 1);
+    }
+
+    // never gets here
+    return 0;
+}
+
+static int bulk_write(int bulk_in, const char *buf, size_t length)
+{
+    size_t count = 0;
+    int ret;
+
+    do {
+        ret = adb_write(bulk_in, buf + count, length - count);
+        if (ret < 0) {
+            if (errno != EINTR)
+                return ret;
+        } else {
+            count += ret;
+        }
+    } while (count < length);
+
+    D("[ bulk_write done fd=%d ]\n", bulk_in);
+    return count;
+}
+
+static int usb_ffs_write(usb_handle *h, const void *data, int len)
+{
+    int n;
+
+    D("about to write (fd=%d, len=%d)\n", h->bulk_in, len);
+    n = bulk_write(h->bulk_in, data, len);
+    if (n != len) {
+        D("ERROR: fd = %d, n = %d, errno = %d (%s)\n",
+            h->bulk_in, n, errno, strerror(errno));
+        return -1;
+    }
+    D("[ done fd=%d ]\n", h->bulk_in);
+    return 0;
+}
+
+static int bulk_read(int bulk_out, char *buf, size_t length)
+{
+    size_t count = 0;
+    int ret;
+
+    do {
+        ret = adb_read(bulk_out, buf + count, length - count);
+        if (ret < 0) {
+            if (errno != EINTR) {
+                D("[ bulk_read failed fd=%d length=%zu count=%zu ]\n",
+                                           bulk_out, length, count);
+                return ret;
+            }
+        } else {
+            count += ret;
+        }
+    } while (count < length);
+
+    return count;
+}
+
+static int usb_ffs_read(usb_handle *h, void *data, int len)
+{
+    int n;
+
+    D("about to read (fd=%d, len=%d)\n", h->bulk_out, len);
+    n = bulk_read(h->bulk_out, data, len);
+    if (n != len) {
+        D("ERROR: fd = %d, n = %d, errno = %d (%s)\n",
+            h->bulk_out, n, errno, strerror(errno));
+        return -1;
+    }
+    D("[ done fd=%d ]\n", h->bulk_out);
+    return 0;
+}
+
+static void usb_ffs_kick(usb_handle *h)
+{
+    int err;
+
+    err = ioctl(h->bulk_in, FUNCTIONFS_CLEAR_HALT);
+    if (err < 0)
+        D("[ kick: source (fd=%d) clear halt failed (%d) ]", h->bulk_in, errno);
+
+    err = ioctl(h->bulk_out, FUNCTIONFS_CLEAR_HALT);
+    if (err < 0)
+        D("[ kick: sink (fd=%d) clear halt failed (%d) ]", h->bulk_out, errno);
+
+    adb_mutex_lock(&h->lock);
+
+    // don't close ep0 here, since we may not need to reinitialize it with
+    // the same descriptors again. if however ep1/ep2 fail to re-open in
+    // init_functionfs, only then would we close and open ep0 again.
+    adb_close(h->bulk_out);
+    adb_close(h->bulk_in);
+    h->bulk_out = h->bulk_in = -1;
+
+    // notify usb_ffs_open_thread that we are disconnected
+    adb_cond_signal(&h->notify);
+    adb_mutex_unlock(&h->lock);
+}
+
+static void usb_ffs_init()
+{
+    usb_handle *h;
+    adb_thread_t tid;
+
+    D("[ usb_init - using FunctionFS ]\n");
+
+    h = calloc(1, sizeof(usb_handle));
+    if (h == 0) {
+        fatal("cannot allocate usb_handle");
+        return;
+    }
+
+    h->write = usb_ffs_write;
+    h->read = usb_ffs_read;
+    h->kick = usb_ffs_kick;
+
+    h->control  = -1;
+    h->bulk_out = -1;
+    h->bulk_out = -1;
+    h->ffs_control_thread_created = false;
+
+    adb_cond_init(&h->notify, 0);
+    adb_mutex_init(&h->lock, 0);
+
+    D("[ usb_init - starting thread ]\n");
+    if (adb_thread_create(&tid, usb_ffs_open_thread, h)){
+        fatal_errno("[ cannot create usb thread ]\n");
+    }
+}
+
+void usb_init()
+{
+    if (access(USB_FFS_ADB_EP0, F_OK) == 0)
+        usb_ffs_init();
+    else
+        usb_adb_init();
+}
+
+void usb_cleanup()
+{
+}
+
+int usb_write(usb_handle *h, const void *data, int len)
+{
+    return h->write(h, data, len);
+}
+
+int usb_read(usb_handle *h, void *data, int len)
+{
+    return h->read(h, data, len);
+}
+int usb_close(usb_handle *h)
+{
+    return 0;
+}
+
+void usb_kick(usb_handle *h)
+{
+    h->kick(h);
+}