diff --git a/osal/usb_osal_nuttx.c b/osal/usb_osal_nuttx.c
index 52b17130..1fb58ca8 100644
--- a/osal/usb_osal_nuttx.c
+++ b/osal/usb_osal_nuttx.c
@@ -131,6 +131,7 @@ int usb_osal_sem_give(usb_osal_sem_t sem)
 
 void usb_osal_sem_reset(usb_osal_sem_t sem)
 {
+    nxsem_reset((sem_t *)sem, 0);
 }
 
 usb_osal_mutex_t usb_osal_mutex_create(void)
diff --git a/platform/nuttx/usbd_cdcacm.c b/platform/nuttx/usbd_cdcacm.c
new file mode 100644
index 00000000..96b0f702
--- /dev/null
+++ b/platform/nuttx/usbd_cdcacm.c
@@ -0,0 +1,343 @@
+/*
+ * Copyright (c) 2025, sakumisu
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <nuttx/kmalloc.h>
+#include <nuttx/mutex.h>
+#include <nuttx/semaphore.h>
+#include <fcntl.h>
+
+#include "usbd_core.h"
+#include "usbd_cdc_acm.h"
+
+#include <nuttx/mm/circbuf.h>
+
+#ifndef CONFIG_USBDEV_CDCACM_RXBUFSIZE
+#define CONFIG_USBDEV_CDCACM_RXBUFSIZE 512
+#endif
+
+#ifndef CONFIG_USBDEV_CDCACM_TXBUFSIZE
+#define CONFIG_USBDEV_CDCACM_TXBUFSIZE 512
+#endif
+
+USB_NOCACHE_RAM_SECTION struct usbdev_serial_s {
+    char name[16];
+    struct circbuf_s circ;
+    uint8_t inep;
+    uint8_t outep;
+    uint32_t rxlen;
+    int error;
+    sem_t txdone_sem;
+    sem_t rxdone_sem;
+    struct usbd_interface ctrl_intf;
+    struct usbd_interface data_intf;
+    __attribute__((aligned(32))) uint8_t cache_tempbuffer[512];
+    __attribute__((aligned(32))) uint8_t cache_rxbuffer[CONFIG_USBDEV_CDCACM_RXBUFSIZE];
+    __attribute__((aligned(32))) uint8_t cache_txbuffer[CONFIG_USBDEV_CDCACM_TXBUFSIZE];
+};
+
+struct usbdev_serial_s *g_usb_cdcacm_serial[8];
+
+void usbd_cdc_acm_bulk_out1(uint8_t busid, uint8_t ep, uint32_t nbytes)
+{
+    g_usb_cdcacm_serial[0]->error = 0;
+    g_usb_cdcacm_serial[0]->rxlen = nbytes;
+    nxsem_post(&g_usb_cdcacm_serial[0]->rxdone_sem);
+}
+
+void usbd_cdc_acm_bulk_in1(uint8_t busid, uint8_t ep, uint32_t nbytes)
+{
+    if ((nbytes % usbd_get_ep_mps(busid, ep)) == 0 && nbytes) {
+        /* send zlp */
+        usbd_ep_start_write(busid, ep, NULL, 0);
+    } else {
+        nxsem_post(&g_usb_cdcacm_serial[0]->txdone_sem);
+    }
+}
+
+void usbd_cdc_acm_bulk_out2(uint8_t busid, uint8_t ep, uint32_t nbytes)
+{
+    g_usb_cdcacm_serial[1]->error = 0;
+    g_usb_cdcacm_serial[1]->rxlen = nbytes;
+    nxsem_post(&g_usb_cdcacm_serial[1]->rxdone_sem);
+}
+
+void usbd_cdc_acm_bulk_in2(uint8_t busid, uint8_t ep, uint32_t nbytes)
+{
+    if ((nbytes % usbd_get_ep_mps(busid, ep)) == 0 && nbytes) {
+        /* send zlp */
+        usbd_ep_start_write(busid, ep, NULL, 0);
+    } else {
+        nxsem_post(&g_usb_cdcacm_serial[1]->txdone_sem);
+    }
+}
+
+void usbd_cdc_acm_bulk_out3(uint8_t busid, uint8_t ep, uint32_t nbytes)
+{
+    g_usb_cdcacm_serial[1]->error = 0;
+    g_usb_cdcacm_serial[2]->rxlen = nbytes;
+    nxsem_post(&g_usb_cdcacm_serial[2]->rxdone_sem);
+}
+
+void usbd_cdc_acm_bulk_in3(uint8_t busid, uint8_t ep, uint32_t nbytes)
+{
+    if ((nbytes % usbd_get_ep_mps(busid, ep)) == 0 && nbytes) {
+        /* send zlp */
+        usbd_ep_start_write(busid, ep, NULL, 0);
+    } else {
+        nxsem_post(&g_usb_cdcacm_serial[2]->txdone_sem);
+    }
+}
+
+/* Character driver methods */
+
+static int usbdev_open(FAR struct file *filep);
+static int usbdev_close(FAR struct file *filep);
+static ssize_t usbdev_read(FAR struct file *filep, FAR char *buffer,
+                           size_t buflen);
+static ssize_t usbdev_write(FAR struct file *filep,
+                            FAR const char *buffer, size_t buflen);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct file_operations g_usbdevops = {
+    usbdev_open,  /* open */
+    usbdev_close, /* close */
+    usbdev_read,  /* read */
+    usbdev_write, /* write */
+    NULL,         /* seek */
+    NULL,         /* ioctl */
+    NULL,         /* mmap */
+    NULL,         /* truncate */
+    NULL          /* poll */
+};
+
+static int usbdev_open(FAR struct file *filep)
+{
+    FAR struct inode *inode = filep->f_inode;
+
+    DEBUGASSERT(inode->i_private);
+
+    if (usb_device_is_configured(0)) {
+        return OK;
+    } else {
+        return -ENODEV;
+    }
+}
+
+static int usbdev_close(FAR struct file *filep)
+{
+    FAR struct inode *inode = filep->f_inode;
+
+    DEBUGASSERT(inode->i_private);
+
+    if (!usb_device_is_configured(0)) {
+        return -ENODEV;
+    }
+
+    return 0;
+}
+
+static ssize_t usbdev_read(FAR struct file *filep, FAR char *buffer,
+                           size_t buflen)
+{
+    FAR struct inode *inode = filep->f_inode;
+    struct usbdev_serial_s *serial;
+    int ret;
+
+    DEBUGASSERT(inode->i_private);
+    serial = (struct usbdev_serial_s *)inode->i_private;
+
+    if (!usb_device_is_configured(0)) {
+        return -ENODEV;
+    }
+
+    while (circbuf_used(&serial->circ) == 0) {
+        nxsem_reset(&serial->rxdone_sem, 0);
+        usbd_ep_start_read(0, serial->outep, serial->cache_tempbuffer, usbd_get_ep_mps(0, serial->outep));
+        ret = nxsem_wait(&serial->rxdone_sem);
+        if (ret < 0) {
+            return ret;
+        }
+        if (serial->error < 0) {
+            return serial->error;
+        }
+#if defined(CONFIG_ARCH_DCACHE) && !defined(CONFIG_USB_DCACHE_ENABLE)
+        up_invalidate_dcache((uintptr_t)serial->cache_tempbuffer, (uintptr_t)(serial->cache_tempbuffer + USB_ALIGN_UP(serial->rxlen, 64)));
+#endif
+        circbuf_overwrite(&serial->circ, serial->cache_tempbuffer, serial->rxlen);
+    }
+    return circbuf_read(&serial->circ, buffer, buflen);
+}
+
+static ssize_t usbdev_write(FAR struct file *filep, FAR const char *buffer,
+                            size_t buflen)
+{
+    FAR struct inode *inode = filep->f_inode;
+    struct usbdev_serial_s *serial;
+    int ret;
+
+    DEBUGASSERT(inode->i_private);
+    serial = (struct usbdev_serial_s *)inode->i_private;
+
+    if (!usb_device_is_configured(0)) {
+        return -ENODEV;
+    }
+
+#ifdef CONFIG_ARCH_DCACHE
+    uint32_t write_len = 0;
+
+    while (write_len < buflen) {
+        uint32_t len = buflen - write_len;
+        if (len > CONFIG_USBDEV_CDCACM_TXBUFSIZE) {
+            len = CONFIG_USBDEV_CDCACM_TXBUFSIZE;
+        }
+        memcpy(serial->cache_txbuffer, buffer + write_len, len);
+#ifndef CONFIG_USB_DCACHE_ENABLE
+        up_clean_dcache((uintptr_t)serial->cache_txbuffer, (uintptr_t)(serial->cache_txbuffer + USB_ALIGN_UP(len, 64)));
+#endif
+        nxsem_reset(&serial->txdone_sem, 0);
+        usbd_ep_start_write(0, serial->inep, serial->cache_txbuffer, len);
+        ret = nxsem_wait(&serial->txdone_sem);
+        if (ret < 0) {
+            return ret;
+        } else {
+            if (serial->error < 0) {
+                return serial->error;
+            }
+            write_len += len;
+        }
+    }
+    return buflen;
+#else
+    nxsem_reset(&serial->txdone_sem, 0);
+    usbd_ep_start_write(0, serial->inep, buffer, buflen);
+    ret = nxsem_wait(&serial->txdone_sem);
+    if (ret < 0) {
+        return ret;
+    } else {
+        return buflen;
+    }
+#endif
+}
+
+static struct usbd_endpoint cdc_out_ep[8] = {
+    { .ep_addr = 0,
+      .ep_cb = usbd_cdc_acm_bulk_out1 },
+    { .ep_addr = 0,
+      .ep_cb = usbd_cdc_acm_bulk_out2 },
+    { .ep_addr = 0,
+      .ep_cb = usbd_cdc_acm_bulk_out3 }
+};
+
+static struct usbd_endpoint cdc_in_ep[8] = {
+    { .ep_addr = 0,
+      .ep_cb = usbd_cdc_acm_bulk_in1 },
+    { .ep_addr = 0,
+      .ep_cb = usbd_cdc_acm_bulk_in2 },
+    { .ep_addr = 0,
+      .ep_cb = usbd_cdc_acm_bulk_in3 }
+};
+
+static void cdcacm_notify_handler1(uint8_t busid, uint8_t event, void *arg)
+{
+    switch (event) {
+        case USBD_EVENT_RESET:
+            break;
+        case USBD_EVENT_DISCONNECTED:
+            g_usb_cdcacm_serial[0]->error = -ENOTCONN;
+            nxsem_post(&g_usb_cdcacm_serial[0]->txdone_sem);
+            nxsem_post(&g_usb_cdcacm_serial[0]->rxdone_sem);
+            break;
+
+        case USBD_EVENT_CONFIGURED:
+            nxsem_post(&g_usb_cdcacm_serial[0]->txdone_sem);
+            nxsem_post(&g_usb_cdcacm_serial[0]->rxdone_sem);
+            break;
+        default:
+            break;
+    }
+}
+
+static void cdcacm_notify_handler2(uint8_t busid, uint8_t event, void *arg)
+{
+    switch (event) {
+        case USBD_EVENT_RESET:
+            break;
+        case USBD_EVENT_DISCONNECTED:
+            g_usb_cdcacm_serial[1]->error = -ENOTCONN;
+            nxsem_post(&g_usb_cdcacm_serial[1]->txdone_sem);
+            nxsem_post(&g_usb_cdcacm_serial[1]->rxdone_sem);
+            break;
+
+        case USBD_EVENT_CONFIGURED:
+            nxsem_post(&g_usb_cdcacm_serial[1]->txdone_sem);
+            nxsem_post(&g_usb_cdcacm_serial[1]->rxdone_sem);
+            break;
+        default:
+            break;
+    }
+}
+
+static void cdcacm_notify_handler3(uint8_t busid, uint8_t event, void *arg)
+{
+    switch (event) {
+        case USBD_EVENT_RESET:
+            break;
+        case USBD_EVENT_DISCONNECTED:
+            g_usb_cdcacm_serial[2]->error = -ENOTCONN;
+            nxsem_post(&g_usb_cdcacm_serial[2]->txdone_sem);
+            nxsem_post(&g_usb_cdcacm_serial[2]->rxdone_sem);
+            break;
+
+        case USBD_EVENT_CONFIGURED:
+            nxsem_post(&g_usb_cdcacm_serial[2]->txdone_sem);
+            nxsem_post(&g_usb_cdcacm_serial[2]->rxdone_sem);
+            break;
+        default:
+            break;
+    }
+}
+
+usbd_notify_handler cdcacm_notify_handler[8] = {
+    cdcacm_notify_handler1,
+    cdcacm_notify_handler2,
+    cdcacm_notify_handler3
+};
+
+void usbd_cdcacm_init(uint8_t busid, uint8_t id, const char *path, uint8_t outep, uint8_t inep)
+{
+    g_usb_cdcacm_serial[id] = kmm_malloc(sizeof(struct usbdev_serial_s));
+    DEBUGASSERT(g_usb_cdcacm_serial[id]);
+
+    memset(g_usb_cdcacm_serial[id], 0, sizeof(struct usbdev_serial_s));
+    strncpy(g_usb_cdcacm_serial[id]->name, path, sizeof(g_usb_cdcacm_serial[id]->name) - 1);
+
+    circbuf_init(&g_usb_cdcacm_serial[id]->circ, g_usb_cdcacm_serial[id]->cache_rxbuffer, CONFIG_USBDEV_CDCACM_RXBUFSIZE);
+
+    nxsem_init(&g_usb_cdcacm_serial[id]->rxdone_sem, 0, 0);
+    nxsem_init(&g_usb_cdcacm_serial[id]->txdone_sem, 0, 0);
+
+    usbd_add_interface(busid, usbd_cdc_acm_init_intf(busid, &g_usb_cdcacm_serial[id]->ctrl_intf));
+    usbd_add_interface(busid, usbd_cdc_acm_init_intf(busid, &g_usb_cdcacm_serial[id]->data_intf));
+    g_usb_cdcacm_serial[id]->ctrl_intf.notify_handler = cdcacm_notify_handler[id];
+
+    cdc_out_ep[id].ep_addr = outep;
+    cdc_in_ep[id].ep_addr = inep;
+    g_usb_cdcacm_serial[id]->outep = outep;
+    g_usb_cdcacm_serial[id]->inep = inep;
+    usbd_add_endpoint(busid, &cdc_out_ep[id]);
+    usbd_add_endpoint(busid, &cdc_in_ep[id]);
+
+    register_driver(path, &g_usbdevops, 0666, g_usb_cdcacm_serial[id]);
+}
+
+void usbd_cdcacm_deinit(uint8_t busid, uint8_t id)
+{
+    unregister_driver(g_usb_cdcacm_serial[id]->name);
+
+    kmm_free(g_usb_cdcacm_serial[id]);
+}
\ No newline at end of file
diff --git a/platform/nuttx/usbd_fs.c b/platform/nuttx/usbd_fs.c
new file mode 100644
index 00000000..3110dc6b
--- /dev/null
+++ b/platform/nuttx/usbd_fs.c
@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2025, sakumisu
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <nuttx/fs/fs.h>
+
+#include "usbd_core.h"
+#include "usbd_msc.h"
+
+#ifndef CONFIG_USBDEV_MSC_THREAD
+#error "CONFIG_USBDEV_MSC_THREAD must be enabled"
+#endif
+
+static FAR struct inode *inode;
+static struct geometry geo;
+static char devpath[32];
+
+void usbd_msc_get_cap(uint8_t busid, uint8_t lun, uint32_t *block_num, uint32_t *block_size)
+{
+    int ret;
+
+    /* Open the block driver */
+
+    ret = open_blockdriver(devpath, 0, &inode);
+    if (ret < 0) {
+        *block_num = 0;
+        *block_size = 0;
+        return;
+    }
+
+    /* Get the drive geometry */
+
+    if (!inode || !inode->u.i_bops || !inode->u.i_bops->geometry ||
+        inode->u.i_bops->geometry(inode, &geo) != OK || !geo.geo_available) {
+        *block_num = 0;
+        *block_size = 0;
+        return;
+    }
+
+    *block_num = geo.geo_nsectors;
+    *block_size = geo.geo_sectorsize;
+
+    USB_LOG_INFO("block_num: %ld, block_size: %ld\n", *block_num, *block_size);
+}
+
+int usbd_msc_sector_read(uint8_t busid, uint8_t lun, uint32_t sector, uint8_t *buffer, uint32_t length)
+{
+    if (inode->u.i_bops->read) {
+        inode->u.i_bops->read(inode, buffer, sector, length / geo.geo_sectorsize);
+    }
+
+    return 0;
+}
+
+int usbd_msc_sector_write(uint8_t busid, uint8_t lun, uint32_t sector, uint8_t *buffer, uint32_t length)
+{
+    if (inode->u.i_bops->write) {
+        inode->u.i_bops->write(inode, buffer, sector, length / geo.geo_sectorsize);
+    }
+
+    return 0;
+}
+
+static struct usbd_interface intf0;
+
+void usbd_msc_init(uint8_t busid, char *path, uint8_t outep, uint8_t inep)
+{
+    memset(devpath, 0, sizeof(devpath));
+    strncpy(devpath, path, sizeof(devpath) - 1);
+    usbd_add_interface(busid, usbd_msc_init_intf(busid, &intf0, outep, inep));
+}
\ No newline at end of file
diff --git a/platform/nuttx/usbh_fs.c b/platform/nuttx/usbh_fs.c
index a55369f1..9f0e2b19 100644
--- a/platform/nuttx/usbh_fs.c
+++ b/platform/nuttx/usbh_fs.c
@@ -3,25 +3,7 @@
  *
  * SPDX-License-Identifier: Apache-2.0
  */
-#include <nuttx/config.h>
-
-#include <inttypes.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include <assert.h>
-#include <errno.h>
-#include <debug.h>
-
-#include <nuttx/irq.h>
-#include <nuttx/kmalloc.h>
-#include <nuttx/signal.h>
-#include <nuttx/arch.h>
-#include <nuttx/wqueue.h>
-#include <nuttx/scsi.h>
 #include <nuttx/fs/fs.h>
-#include <nuttx/mutex.h>
 
 #include "usbh_core.h"
 #include "usbh_msc.h"
@@ -38,6 +20,57 @@
 
 #define DEV_FORMAT "/dev/sd%c"
 
+static int nuttx_errorcode(int error)
+{
+    int err = 0;
+
+    switch (error) {
+        case -USB_ERR_NOMEM:
+            err = -EIO;
+            break;
+        case -USB_ERR_INVAL:
+            err = -EINVAL;
+            break;
+        case -USB_ERR_NODEV:
+            err = -ENODEV;
+            break;
+        case -USB_ERR_NOTCONN:
+            err = -ENOTCONN;
+            break;
+        case -USB_ERR_NOTSUPP:
+            err = -EIO;
+            break;
+        case -USB_ERR_BUSY:
+            err = -EBUSY;
+            break;
+        case -USB_ERR_RANGE:
+            err = -ERANGE;
+            break;
+        case -USB_ERR_STALL:
+            err = -EPERM;
+            break;
+        case -USB_ERR_NAK:
+            err = -EAGAIN;
+            break;
+        case -USB_ERR_DT:
+            err = -EIO;
+            break;
+        case -USB_ERR_IO:
+            err = -EIO;
+            break;
+        case -USB_ERR_SHUTDOWN:
+            err = -ESHUTDOWN;
+            break;
+        case -USB_ERR_TIMEOUT:
+            err = -ETIMEDOUT;
+            break;
+
+        default:
+            break;
+    }
+    return err;
+}
+
 static int usbhost_open(FAR struct inode *inode);
 static int usbhost_close(FAR struct inode *inode);
 static ssize_t usbhost_read(FAR struct inode *inode, unsigned char *buffer,
@@ -90,18 +123,14 @@ static ssize_t usbhost_read(FAR struct inode *inode, unsigned char *buffer,
     DEBUGASSERT(inode->i_private);
     msc_class = (struct usbh_msc *)inode->i_private;
 
-    if (msc_class->hport && msc_class->hport->connected) {
-        ret = usbh_msc_scsi_read10(msc_class, startsector, (uint8_t *)buffer, nsectors);
-        if (ret < 0) {
-            return ret;
-        } else {
-#ifdef CONFIG_ARCH_DCACHE
-            up_invalidate_dcache((uintptr_t)buffer, (uintptr_t)(buffer + nsectors * msc_class->blocksize));
-#endif
-            return nsectors;
-        }
+    ret = usbh_msc_scsi_read10(msc_class, startsector, (uint8_t *)buffer, nsectors);
+    if (ret < 0) {
+        return nuttx_errorcode(ret);
     } else {
-        return -ENODEV;
+#if defined(CONFIG_ARCH_DCACHE) && !defined(CONFIG_USB_DCACHE_ENABLE)
+        up_invalidate_dcache((uintptr_t)buffer, (uintptr_t)(buffer + nsectors * msc_class->blocksize));
+#endif
+        return nsectors;
     }
 }
 
@@ -115,18 +144,14 @@ static ssize_t usbhost_write(FAR struct inode *inode,
     DEBUGASSERT(inode->i_private);
     msc_class = (struct usbh_msc *)inode->i_private;
 
-    if (msc_class->hport && msc_class->hport->connected) {
-#ifdef CONFIG_ARCH_DCACHE
-        up_flush_dcache((uintptr_t)buffer, (uintptr_t)(buffer + nsectors * msc_class->blocksize));
+#if defined(CONFIG_ARCH_DCACHE) && !defined(CONFIG_USB_DCACHE_ENABLE)
+    up_clean_dcache((uintptr_t)buffer, (uintptr_t)(buffer + nsectors * msc_class->blocksize));
 #endif
-        ret = usbh_msc_scsi_write10(msc_class, startsector, (uint8_t *)buffer, nsectors);
-        if (ret < 0) {
-            return ret;
-        } else {
-            return nsectors;
-        }
+    ret = usbh_msc_scsi_write10(msc_class, startsector, (uint8_t *)buffer, nsectors);
+    if (ret < 0) {
+        return nuttx_errorcode(ret);
     } else {
-        return -ENODEV;
+        return nsectors;
     }
 }
 
@@ -147,7 +172,7 @@ static int usbhost_geometry(FAR struct inode *inode,
         geometry->geo_nsectors = msc_class->blocknum;
         geometry->geo_sectorsize = msc_class->blocksize;
 
-        uinfo("nsectors: %" PRIdOFF " sectorsize: %" PRIi16 "\n",
+        USB_LOG_DBG("nsectors: %ld, sectorsize: %ld\n",
               geometry->geo_nsectors, geometry->geo_sectorsize);
         return OK;
     } else {
diff --git a/platform/nuttx/usbh_net.c b/platform/nuttx/usbh_net.c
index d84165d5..c7af90f9 100644
--- a/platform/nuttx/usbh_net.c
+++ b/platform/nuttx/usbh_net.c
@@ -3,16 +3,6 @@
  *
  * SPDX-License-Identifier: Apache-2.0
  */
-#include <nuttx/config.h>
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <semaphore.h>
-#include <assert.h>
-#include <errno.h>
-#include <debug.h>
-
 #include <nuttx/net/ip.h>
 #include <nuttx/net/netdev.h>
 
diff --git a/platform/nuttx/usbh_serial.c b/platform/nuttx/usbh_serial.c
new file mode 100644
index 00000000..1538714c
--- /dev/null
+++ b/platform/nuttx/usbh_serial.c
@@ -0,0 +1,237 @@
+/*
+ * Copyright (c) 2025, sakumisu
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <nuttx/kmalloc.h>
+#include <nuttx/mutex.h>
+#include <nuttx/semaphore.h>
+
+#include "usbh_core.h"
+#include "usbh_cdc_acm.h"
+
+#include <nuttx/mm/circbuf.h>
+
+#define DEV_FORMAT "/dev/ttyACM%d"
+
+#ifndef CONFIG_USBHOST_CDCACM_RXBUFSIZE
+#define CONFIG_USBHOST_CDCACM_RXBUFSIZE 512
+#endif
+
+#ifndef CONFIG_USBHOST_CDCACM_TXBUFSIZE
+#define CONFIG_USBHOST_CDCACM_TXBUFSIZE 512
+#endif
+
+struct usbhost_serial_s {
+    struct circbuf_s circ;
+    __attribute__((aligned(32))) uint8_t cache_rxbuffer[CONFIG_USBHOST_CDCACM_RXBUFSIZE];
+    __attribute__((aligned(32))) uint8_t cache_txbuffer[CONFIG_USBHOST_CDCACM_TXBUFSIZE];
+};
+
+static int nuttx_errorcode(int error)
+{
+    int err = 0;
+
+    switch (error) {
+        case -USB_ERR_NOMEM:
+            err = -EIO;
+            break;
+        case -USB_ERR_INVAL:
+            err = -EINVAL;
+            break;
+        case -USB_ERR_NODEV:
+            err = -ENODEV;
+            break;
+        case -USB_ERR_NOTCONN:
+            err = -ENOTCONN;
+            break;
+        case -USB_ERR_NOTSUPP:
+            err = -EIO;
+            break;
+        case -USB_ERR_BUSY:
+            err = -EBUSY;
+            break;
+        case -USB_ERR_RANGE:
+            err = -ERANGE;
+            break;
+        case -USB_ERR_STALL:
+            err = -EPERM;
+            break;
+        case -USB_ERR_NAK:
+            err = -EAGAIN;
+            break;
+        case -USB_ERR_DT:
+            err = -EIO;
+            break;
+        case -USB_ERR_IO:
+            err = -EIO;
+            break;
+        case -USB_ERR_SHUTDOWN:
+            err = -ESHUTDOWN;
+            break;
+        case -USB_ERR_TIMEOUT:
+            err = -ETIMEDOUT;
+            break;
+
+        default:
+            break;
+    }
+    return err;
+}
+
+/* Character driver methods */
+
+static int usbhost_open(FAR struct file *filep);
+static int usbhost_close(FAR struct file *filep);
+static ssize_t usbhost_read(FAR struct file *filep, FAR char *buffer,
+                            size_t buflen);
+static ssize_t usbhost_write(FAR struct file *filep,
+                             FAR const char *buffer, size_t buflen);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct file_operations g_usbhostops = {
+    usbhost_open,  /* open */
+    usbhost_close, /* close */
+    usbhost_read,  /* read */
+    usbhost_write, /* write */
+    NULL,          /* seek */
+    NULL,          /* ioctl */
+    NULL,          /* mmap */
+    NULL,          /* truncate */
+    NULL           /* poll */
+};
+
+static int usbhost_open(FAR struct file *filep)
+{
+    struct usbh_cdc_acm *cdc_acm_class;
+    FAR struct inode *inode = filep->f_inode;
+
+    DEBUGASSERT(inode->i_private);
+    cdc_acm_class = (struct usbh_cdc_acm *)inode->i_private;
+
+    if (cdc_acm_class->hport && cdc_acm_class->hport->connected) {
+        return OK;
+    } else {
+        return -ENODEV;
+    }
+}
+
+static int usbhost_close(FAR struct file *filep)
+{
+    FAR struct inode *inode = filep->f_inode;
+
+    DEBUGASSERT(inode->i_private);
+    return 0;
+}
+
+static ssize_t usbhost_read(FAR struct file *filep, FAR char *buffer,
+                            size_t buflen)
+{
+    struct usbh_cdc_acm *cdc_acm_class;
+    FAR struct inode *inode = filep->f_inode;
+    struct usbhost_serial_s *serial;
+    __attribute__((aligned(32))) uint8_t cache_tempbuffer[512];
+    int ret;
+
+    DEBUGASSERT(inode->i_private || cdc_acm_class->user_data);
+    cdc_acm_class = (struct usbh_cdc_acm *)inode->i_private;
+    serial = cdc_acm_class->user_data;
+
+    while (circbuf_used(&serial->circ) == 0) {
+        ret = usbh_cdc_acm_bulk_in_transfer(cdc_acm_class, cache_tempbuffer, cdc_acm_class->bulkin->wMaxPacketSize, 0xffffffff);
+        if (ret < 0) {
+            return nuttx_errorcode(ret);
+        }
+#if defined(CONFIG_ARCH_DCACHE) && !defined(CONFIG_USB_DCACHE_ENABLE)
+        up_invalidate_dcache((uintptr_t)cache_tempbuffer, (uintptr_t)(cache_tempbuffer + cdc_acm_class->bulkin->wMaxPacketSize));
+#endif
+        circbuf_overwrite(&serial->circ, cache_tempbuffer, USB_ALIGN_UP(ret, 64));
+    }
+    return circbuf_read(&serial->circ, buffer, buflen);
+}
+
+static ssize_t usbhost_write(FAR struct file *filep, FAR const char *buffer,
+                             size_t buflen)
+{
+    struct usbh_cdc_acm *cdc_acm_class;
+    FAR struct inode *inode = filep->f_inode;
+    struct usbhost_serial_s *serial;
+    int ret;
+
+    DEBUGASSERT(inode->i_private || cdc_acm_class->user_data);
+    cdc_acm_class = (struct usbh_cdc_acm *)inode->i_private;
+    serial = cdc_acm_class->user_data;
+
+#ifdef CONFIG_ARCH_DCACHE
+    uint32_t write_len = 0;
+
+    while (write_len < buflen) {
+        uint32_t len = buflen - write_len;
+        if (len > CONFIG_USBHOST_CDCACM_TXBUFSIZE) {
+            len = CONFIG_USBHOST_CDCACM_TXBUFSIZE;
+        }
+        memcpy(serial->cache_txbuffer, buffer + write_len, len);
+#ifndef CONFIG_USB_DCACHE_ENABLE
+        up_clean_dcache((uintptr_t)serial->cache_txbuffer, (uintptr_t)(serial->cache_txbuffer + USB_ALIGN_UP(len, 64)));
+#endif
+        ret = usbh_cdc_acm_bulk_out_transfer(cdc_acm_class, serial->cache_txbuffer, len, 0xffffffff);
+        if (ret < 0) {
+            return nuttx_errorcode(ret);
+        } else {
+            write_len += len;
+        }
+    }
+    return buflen;
+#else
+    ret = usbh_cdc_acm_bulk_out_transfer(cdc_acm_class, (uint8_t *)buffer, buflen, 0xffffffff);
+    if (ret < 0) {
+        return nuttx_errorcode(ret);
+    } else {
+        return buflen;
+    }
+#endif
+}
+
+void usbh_cdc_acm_run(struct usbh_cdc_acm *cdc_acm_class)
+{
+    char devname[32];
+    struct usbhost_serial_s *serial;
+
+    snprintf(devname, CONFIG_USBHOST_DEV_NAMELEN, DEV_FORMAT, cdc_acm_class->minor);
+
+    serial = kmm_malloc(sizeof(struct usbhost_serial_s));
+    DEBUGASSERT(serial);
+
+    memset(serial, 0, sizeof(struct usbhost_serial_s));
+
+    circbuf_init(&serial->circ, serial->cache_rxbuffer, CONFIG_USBHOST_CDCACM_RXBUFSIZE);
+
+    cdc_acm_class->user_data = serial;
+
+    struct cdc_line_coding linecoding;
+
+    linecoding.dwDTERate = 115200;
+    linecoding.bDataBits = 8;
+    linecoding.bParityType = 0;
+    linecoding.bCharFormat = 0;
+    usbh_cdc_acm_set_line_coding(cdc_acm_class, &linecoding);
+    usbh_cdc_acm_set_line_state(cdc_acm_class, true, false);
+
+    register_driver(devname, &g_usbhostops, 0666, cdc_acm_class);
+}
+
+void usbh_cdc_acm_stop(struct usbh_cdc_acm *cdc_acm_class)
+{
+    char devname[32];
+    struct usbhost_serial_s *serial;
+
+    snprintf(devname, CONFIG_USBHOST_DEV_NAMELEN, DEV_FORMAT, cdc_acm_class->minor);
+    unregister_driver(devname);
+
+    serial = cdc_acm_class->user_data;
+
+    kmm_free(serial);
+}
\ No newline at end of file