add pl2303 host driver

SConscript

@@ -182,6 +182,8 @@ if GetDepend(['PKG_CHERRYUSB_HOST']):
         src += Glob('class/vendor/serial/usbh_ch34x.c')
     if GetDepend(['PKG_CHERRYUSB_HOST_CP210X']):
         src += Glob('class/vendor/serial/usbh_cp210x.c')
+    if GetDepend(['PKG_CHERRYUSB_HOST_PL2303']):
+        src += Glob('class/vendor/serial/usbh_pl2303.c')
 
     if GetDepend(['PKG_CHERRYUSB_HOST_TEMPLATE']):
         src += Glob('demo/usb_host.c')

cherryusb.cmake

@@ -193,6 +193,9 @@ if(CONFIG_CHERRYUSB_HOST)
     if(CONFIG_CHERRYUSB_HOST_FTDI)
     list(APPEND cherryusb_srcs ${CMAKE_CURRENT_LIST_DIR}/class/vendor/serial/usbh_ftdi.c)
     endif()
+    if(CONFIG_CHERRYUSB_HOST_PL2303)
+    list(APPEND cherryusb_srcs ${CMAKE_CURRENT_LIST_DIR}/class/vendor/serial/usbh_pl2303.c)
+    endif()
 
     if(DEFINED CONFIG_CHERRYUSB_HOST_HCD)
         if("${CONFIG_CHERRYUSB_HOST_HCD}" STREQUAL "ehci_bouffalo")

class/vendor/serial/usbh_pl2303.c

@@ -0,0 +1,426 @@
+/*
+ * Copyright (c) 2024, sakumisu
+ * Copyright (c) 2024, Derek Konigsberg
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include "usbh_core.h"
+#include "usbh_pl2303.h"
+
+#undef USB_DBG_TAG
+#define USB_DBG_TAG "usbh_pl2303"
+#include "usb_log.h"
+
+#define DEV_FORMAT "/dev/ttyUSB%d"
+
+USB_NOCACHE_RAM_SECTION USB_MEM_ALIGNX uint8_t g_pl2303_buf[64];
+
+#define CONFIG_USBHOST_MAX_PL2303_CLASS 4
+
+#define UT_WRITE_VENDOR_DEVICE   (USB_REQUEST_DIR_OUT | USB_REQUEST_VENDOR | USB_REQUEST_RECIPIENT_DEVICE)
+#define UT_READ_VENDOR_DEVICE    (USB_REQUEST_DIR_IN | USB_REQUEST_VENDOR | USB_REQUEST_RECIPIENT_DEVICE)
+
+static struct usbh_pl2303 g_pl2303_class[CONFIG_USBHOST_MAX_PL2303_CLASS];
+static uint32_t g_devinuse = 0;
+
+static struct usbh_pl2303 *usbh_pl2303_class_alloc(void)
+{
+    int devno;
+
+    for (devno = 0; devno < CONFIG_USBHOST_MAX_PL2303_CLASS; devno++) {
+        if ((g_devinuse & (1 << devno)) == 0) {
+            g_devinuse |= (1 << devno);
+            memset(&g_pl2303_class[devno], 0, sizeof(struct usbh_pl2303));
+            g_pl2303_class[devno].minor = devno;
+            return &g_pl2303_class[devno];
+        }
+    }
+    return NULL;
+}
+
+static void usbh_pl2303_class_free(struct usbh_pl2303 *pl2303_class)
+{
+    int devno = pl2303_class->minor;
+
+    if (devno >= 0 && devno < 32) {
+        g_devinuse &= ~(1 << devno);
+    }
+    memset(pl2303_class, 0, sizeof(struct usbh_pl2303));
+}
+
+static int usbh_pl2303_get_chiptype(struct usbh_pl2303 *pl2303_class)
+{
+    int ret = 0;
+
+    switch (pl2303_class->hport->device_desc.bcdDevice) {
+        case 0x0300:
+            pl2303_class->chiptype = USBH_PL2303_TYPE_PL2303HX;
+            /* or TA, that is HX with external crystal */
+            break;
+        case 0x0400:
+            pl2303_class->chiptype = USBH_PL2303_TYPE_PL2303HXD;
+            /* or EA, that is HXD with ESD protection */
+            /* or RA, that has internal voltage level converter that works only up to 1Mbaud (!) */
+            break;
+        case 0x0500:
+            pl2303_class->chiptype = USBH_PL2303_TYPE_PL2303HXD;
+            /* in fact it's TB, that is HXD with external crystal */
+            break;
+        default:
+            /* NOTE: I have no info about the bcdDevice for the base PL2303 (up to 1.2Mbaud,
+           only fixed rates) and for PL2303SA (8-pin chip, up to 115200 baud */
+            /* Determine the chip type.  This algorithm is taken from Linux. */
+            if (pl2303_class->hport->device_desc.bDeviceClass == 0x02) {
+                pl2303_class->chiptype = USBH_PL2303_TYPE_PL2303;
+            } else if (pl2303_class->hport->device_desc.bMaxPacketSize0 == 0x40) {
+                pl2303_class->chiptype = USBH_PL2303_TYPE_PL2303HX;
+            } else {
+                pl2303_class->chiptype = USBH_PL2303_TYPE_PL2303;
+            }
+            break;
+    }
+
+    /*
+     * The new chip revision PL2303HXN is only compatible with the new
+     * PLCOM_SET_REQUEST_PL2303HXN command. Issuing the old command
+     * PLCOM_SET_REQUEST to the new chip raises an error. Thus, PL2303HX
+     * and PL2303HXN can be distinguished by issuing an old-style request
+     * (on a status register) to the new chip and checking the error.
+     */
+    if (pl2303_class->chiptype == USBH_PL2303_TYPE_PL2303HX) {
+        struct usb_setup_packet *setup = pl2303_class->hport->setup;
+
+        setup->bmRequestType = UT_READ_VENDOR_DEVICE;
+        setup->bRequest = PL2303_SET_REQUEST;
+        setup->wValue = PL2303_STATUS_REG_PL2303HX;
+        setup->wIndex = 0;
+        setup->wLength = 1;
+
+        ret = usbh_control_transfer(pl2303_class->hport, setup, g_pl2303_buf);
+        if (ret == -USB_ERR_STALL) {
+            pl2303_class->chiptype = USBH_PL2303_TYPE_PL2303HXN;
+            ret = 0;
+        } else if (ret < 0) {
+            USB_LOG_WRN("Error checking chip type: %d\r\n", ret);
+            return ret;
+        }
+    }
+
+    switch (pl2303_class->chiptype) {
+        case USBH_PL2303_TYPE_PL2303:
+            USB_LOG_INFO("chiptype = 2303\r\n");
+            break;
+        case USBH_PL2303_TYPE_PL2303HX:
+            USB_LOG_INFO("chiptype = 2303HX/TA\r\n");
+            break;
+        case USBH_PL2303_TYPE_PL2303HXN:
+            USB_LOG_INFO("chiptype = 2303HXN\r\n");
+            break;
+        case USBH_PL2303_TYPE_PL2303HXD:
+            USB_LOG_INFO("chiptype = 2303HXD/TB/RA/EA\r\n");
+            break;
+        default:
+            USB_LOG_INFO("chiptype = [%d]\r\n", pl2303_class->chiptype);
+            break;
+    }
+
+    return ret;
+}
+
+static int usbh_pl2303_do(struct usbh_pl2303 *pl2303_class,
+                          uint8_t req_type, uint8_t request, uint16_t value, uint16_t index,
+                          uint16_t length)
+{
+    struct usb_setup_packet *setup = pl2303_class->hport->setup;
+
+    setup->bmRequestType = req_type;
+    setup->bRequest = request;
+    setup->wValue = value;
+    setup->wIndex = index;
+    setup->wLength = length;
+
+    return usbh_control_transfer(pl2303_class->hport, setup, g_pl2303_buf);
+}
+
+int usbh_pl2303_set_line_coding(struct usbh_pl2303 *pl2303_class, struct cdc_line_coding *line_coding)
+{
+    struct usb_setup_packet *setup = pl2303_class->hport->setup;
+
+    setup->bmRequestType = USB_REQUEST_DIR_OUT | USB_REQUEST_CLASS | USB_REQUEST_RECIPIENT_INTERFACE;
+    setup->bRequest = CDC_REQUEST_SET_LINE_CODING;
+    setup->wValue = 0;
+    setup->wIndex = pl2303_class->intf;
+    setup->wLength = 7;
+
+    memcpy(g_pl2303_buf, line_coding, sizeof(struct cdc_line_coding));
+
+    return usbh_control_transfer(pl2303_class->hport, setup, g_pl2303_buf);
+}
+
+int usbh_pl2303_get_line_coding(struct usbh_pl2303 *pl2303_class, struct cdc_line_coding *line_coding)
+{
+    struct usb_setup_packet *setup = pl2303_class->hport->setup;
+    int ret;
+
+    setup->bmRequestType = USB_REQUEST_DIR_IN | USB_REQUEST_CLASS | USB_REQUEST_RECIPIENT_INTERFACE;
+    setup->bRequest = CDC_REQUEST_GET_LINE_CODING;
+    setup->wValue = 0;
+    setup->wIndex = pl2303_class->intf;
+    setup->wLength = 7;
+
+    ret = usbh_control_transfer(pl2303_class->hport, setup, g_pl2303_buf);
+    if (ret < 0) {
+        return ret;
+    }
+    memcpy(line_coding, g_pl2303_buf, sizeof(struct cdc_line_coding));
+    return ret;
+}
+
+int usbh_pl2303_set_line_state(struct usbh_pl2303 *pl2303_class, bool dtr, bool rts)
+{
+    struct usb_setup_packet *setup = pl2303_class->hport->setup;
+
+    setup->bmRequestType = USB_REQUEST_DIR_OUT | USB_REQUEST_CLASS | USB_REQUEST_RECIPIENT_INTERFACE;
+    setup->bRequest = CDC_REQUEST_SET_CONTROL_LINE_STATE;
+    setup->wValue = (dtr << 0) | (rts << 1);
+    setup->wIndex = pl2303_class->intf;
+    setup->wLength = 0;
+
+    return usbh_control_transfer(pl2303_class->hport, setup, NULL);
+}
+
+static int usbh_pl2303_connect(struct usbh_hubport *hport, uint8_t intf)
+{
+    struct usb_endpoint_descriptor *ep_desc;
+    int ret = 0;
+
+    struct usbh_pl2303 *pl2303_class = usbh_pl2303_class_alloc();
+    if (pl2303_class == NULL) {
+        USB_LOG_ERR("Fail to alloc pl2303_class\r\n");
+        return -USB_ERR_NOMEM;
+    }
+
+    pl2303_class->hport = hport;
+    pl2303_class->intf = intf;
+
+    hport->config.intf[intf].priv = pl2303_class;
+
+    do {
+        ret = usbh_pl2303_get_chiptype(pl2303_class);
+        if (ret < 0) {
+            break;
+        }
+
+        /* Startup reset sequence, if necessary for the chip type */
+        if (pl2303_class->chiptype != USBH_PL2303_TYPE_PL2303HXN) {
+            struct usb_setup_packet *setup = pl2303_class->hport->setup;
+
+            setup->bmRequestType = UT_WRITE_VENDOR_DEVICE;
+            setup->bRequest = PL2303_SET_REQUEST;
+            setup->wValue = 0;
+            setup->wIndex = pl2303_class->intf;
+            setup->wLength = 0;
+
+            ret = usbh_control_transfer(pl2303_class->hport, setup, g_pl2303_buf);
+            if (ret < 0) {
+                USB_LOG_WRN("Initialization reset failed: %d\r\n", ret);
+                break;
+            }
+        }
+
+        if (pl2303_class->chiptype == USBH_PL2303_TYPE_PL2303) {
+            /* HX variants seem to lock up after a clear stall request. */
+            /*
+             * The FreeBSD code sets the stall flags on the in and out pipes
+             * here. Have no idea exactly how to do this, or if it is necessary.
+             * May just leave this code unwritten until test hardware is available.
+             */
+        } else if (pl2303_class->chiptype == USBH_PL2303_TYPE_PL2303HX || pl2303_class->chiptype == USBH_PL2303_TYPE_PL2303HXD) {
+            /* Reset upstream data pipes */
+            ret = usbh_pl2303_do(pl2303_class, UT_WRITE_VENDOR_DEVICE, PL2303_SET_REQUEST, 8, 0, 0);
+            if (ret < 0) {
+                USB_LOG_WRN("Could not reset upstream data pipes (8,0): %d\r\n", ret);
+                break;
+            }
+            ret = usbh_pl2303_do(pl2303_class, UT_WRITE_VENDOR_DEVICE, PL2303_SET_REQUEST, 9, 0, 0);
+            if (ret < 0) {
+                USB_LOG_WRN("Could not reset upstream data pipes (9,0): %d\r\n", ret);
+                break;
+            }
+        } else if (pl2303_class->chiptype == USBH_PL2303_TYPE_PL2303HXN) {
+            /* Reset upstream data pipes */
+            ret = usbh_pl2303_do(pl2303_class, UT_WRITE_VENDOR_DEVICE, PL2303_SET_REQUEST_PL2303HXN, 0x07, 0x03, 0);
+            if (ret < 0) {
+                USB_LOG_WRN("Could not reset upstream data pipes (7,3): %d\r\n", ret);
+                break;
+            }
+        }
+
+        /* Final device initialization, if necessary for the chip type */
+        if (pl2303_class->chiptype != USBH_PL2303_TYPE_PL2303HXN) {
+            if (usbh_pl2303_do(pl2303_class, UT_READ_VENDOR_DEVICE, PL2303_SET_REQUEST, 0x8484, 0, 1) < 0 ||
+                usbh_pl2303_do(pl2303_class, UT_WRITE_VENDOR_DEVICE, PL2303_SET_REQUEST, 0x0404, 0, 0) < 0 ||
+                usbh_pl2303_do(pl2303_class, UT_READ_VENDOR_DEVICE, PL2303_SET_REQUEST, 0x8484, 0, 1) < 0 ||
+                usbh_pl2303_do(pl2303_class, UT_READ_VENDOR_DEVICE, PL2303_SET_REQUEST, 0x8383, 0, 1) < 0 ||
+                usbh_pl2303_do(pl2303_class, UT_READ_VENDOR_DEVICE, PL2303_SET_REQUEST, 0x8484, 0, 1) < 0 ||
+                usbh_pl2303_do(pl2303_class, UT_WRITE_VENDOR_DEVICE, PL2303_SET_REQUEST, 0x0404, 1, 0) < 0 ||
+                usbh_pl2303_do(pl2303_class, UT_READ_VENDOR_DEVICE, PL2303_SET_REQUEST, 0x8484, 0, 1) < 0 ||
+                usbh_pl2303_do(pl2303_class, UT_READ_VENDOR_DEVICE, PL2303_SET_REQUEST, 0x8383, 0, 1) < 0 ||
+                usbh_pl2303_do(pl2303_class, UT_WRITE_VENDOR_DEVICE, PL2303_SET_REQUEST, 0, 1, 0) < 0 ||
+                usbh_pl2303_do(pl2303_class, UT_WRITE_VENDOR_DEVICE, PL2303_SET_REQUEST, 1, 0, 0) < 0) {
+                USB_LOG_WRN("Could not complete init sequence\r\n");
+                ret = -USB_ERR_INVAL;
+                break;
+            }
+
+            if (pl2303_class->chiptype != USBH_PL2303_TYPE_PL2303) {
+                ret = usbh_pl2303_do(pl2303_class, UT_WRITE_VENDOR_DEVICE, PL2303_SET_REQUEST, 2, 0x44, 0);
+            } else {
+                ret = usbh_pl2303_do(pl2303_class, UT_WRITE_VENDOR_DEVICE, PL2303_SET_REQUEST, 2, 0x24, 0);
+            }
+            if (ret < 0) {
+                USB_LOG_WRN("Could not complete final init request: %d\r\n", ret);
+                break;
+            }
+        }
+    } while (0);
+
+    if (ret < 0) {
+        USB_LOG_ERR("Failed to initialize PL2303 device: %d\r\n", ret);
+        return ret;
+    }
+
+    for (uint8_t i = 0; i < hport->config.intf[intf].altsetting[0].intf_desc.bNumEndpoints; i++) {
+        ep_desc = &hport->config.intf[intf].altsetting[0].ep[i].ep_desc;
+        if (USB_GET_ENDPOINT_TYPE(ep_desc->bmAttributes) == USB_ENDPOINT_TYPE_INTERRUPT) {
+            continue;
+        } else {
+            if (ep_desc->bEndpointAddress & 0x80) {
+                USBH_EP_INIT(pl2303_class->bulkin, ep_desc);
+            } else {
+                USBH_EP_INIT(pl2303_class->bulkout, ep_desc);
+            }
+        }
+    }
+
+    snprintf(hport->config.intf[intf].devname, CONFIG_USBHOST_DEV_NAMELEN, DEV_FORMAT, pl2303_class->minor);
+
+    USB_LOG_INFO("Register PL2303 Class:%s\r\n", hport->config.intf[intf].devname);
+
+#if 0
+    USB_LOG_INFO("Test pl2303 rx and tx and rx for 5 times, baudrate is 115200\r\n");
+
+    struct cdc_line_coding linecoding;
+    uint8_t count = 5;
+
+    linecoding.dwDTERate = 115200;
+    linecoding.bDataBits = 8;
+    linecoding.bParityType = 0;
+    linecoding.bCharFormat = 0;
+    usbh_pl2303_set_line_coding(pl2303_class, &linecoding);
+    usbh_pl2303_set_line_state(pl2303_class, true, false);
+
+    memset(g_pl2303_buf, 'a', sizeof(g_pl2303_buf));
+    ret = usbh_pl2303_bulk_out_transfer(pl2303_class, g_pl2303_buf, sizeof(g_pl2303_buf), 0xfffffff);
+    USB_LOG_RAW("out ret:%d\r\n", ret);
+    while (count--) {
+        ret = usbh_pl2303_bulk_in_transfer(pl2303_class, g_pl2303_buf, sizeof(g_pl2303_buf), 0xfffffff);
+        USB_LOG_RAW("in ret:%d\r\n", ret);
+        if (ret > 0) {
+            for (uint32_t i = 0; i < ret; i++) {
+                USB_LOG_RAW("%02x ", g_pl2303_buf[i]);
+            }
+        }
+        USB_LOG_RAW("\r\n");
+    }
+#endif
+
+    usbh_pl2303_run(pl2303_class);
+    return ret;
+}
+
+static int usbh_pl2303_disconnect(struct usbh_hubport *hport, uint8_t intf)
+{
+    int ret = 0;
+
+    struct usbh_pl2303 *pl2303_class = (struct usbh_pl2303 *)hport->config.intf[intf].priv;
+
+    if (pl2303_class) {
+        if (pl2303_class->bulkin) {
+            usbh_kill_urb(&pl2303_class->bulkin_urb);
+        }
+
+        if (pl2303_class->bulkout) {
+            usbh_kill_urb(&pl2303_class->bulkout_urb);
+        }
+
+        if (hport->config.intf[intf].devname[0] != '\0') {
+            USB_LOG_INFO("Unregister PL2303 Class:%s\r\n", hport->config.intf[intf].devname);
+            usbh_pl2303_stop(pl2303_class);
+        }
+
+        usbh_pl2303_class_free(pl2303_class);
+    }
+
+    return ret;
+}
+
+int usbh_pl2303_bulk_in_transfer(struct usbh_pl2303 *pl2303_class, uint8_t *buffer, uint32_t buflen, uint32_t timeout)
+{
+    int ret;
+    struct usbh_urb *urb = &pl2303_class->bulkin_urb;
+
+    usbh_bulk_urb_fill(urb, pl2303_class->hport, pl2303_class->bulkin, buffer, buflen, timeout, NULL, NULL);
+    ret = usbh_submit_urb(urb);
+    if (ret == 0) {
+        ret = urb->actual_length;
+    }
+    return ret;
+}
+
+int usbh_pl2303_bulk_out_transfer(struct usbh_pl2303 *pl2303_class, uint8_t *buffer, uint32_t buflen, uint32_t timeout)
+{
+    int ret;
+    struct usbh_urb *urb = &pl2303_class->bulkout_urb;
+
+    usbh_bulk_urb_fill(urb, pl2303_class->hport, pl2303_class->bulkout, buffer, buflen, timeout, NULL, NULL);
+    ret = usbh_submit_urb(urb);
+    if (ret == 0) {
+        ret = urb->actual_length;
+    }
+    return ret;
+}
+
+__WEAK void usbh_pl2303_run(struct usbh_pl2303 *pl2303_class)
+{
+}
+
+__WEAK void usbh_pl2303_stop(struct usbh_pl2303 *pl2303_class)
+{
+}
+
+static const uint16_t pl2303_id_table[][2] = {
+    { 0x067B, 0x2303 }, // PL2303 Serial (ATEN/IOGEAR UC232A)
+    { 0x067B, 0x23A3 }, // PL2303HXN Serial, type GC
+    { 0x067B, 0x23B3 }, // PL2303HXN Serial, type GB
+    { 0x067B, 0x23C3 }, // PL2303HXN Serial, type GT
+    { 0x067B, 0x23D3 }, // PL2303HXN Serial, type GL
+    { 0x067B, 0x23E3 }, // PL2303HXN Serial, type GE
+    { 0x067B, 0x23F3 }, // PL2303HXN Serial, type GS
+    { 0, 0 },
+};
+
+const struct usbh_class_driver pl2303_class_driver = {
+    .driver_name = "pl2303",
+    .connect = usbh_pl2303_connect,
+    .disconnect = usbh_pl2303_disconnect
+};
+
+CLASS_INFO_DEFINE const struct usbh_class_info pl2303_class_info = {
+    .match_flags = USB_CLASS_MATCH_VID_PID | USB_CLASS_MATCH_INTF_CLASS,
+    .class = 0xff,
+    .subclass = 0x00,
+    .protocol = 0x00,
+    .id_table = pl2303_id_table,
+    .class_driver = &pl2303_class_driver
+};

class/vendor/serial/usbh_pl2303.h

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2024, sakumisu
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#ifndef USBH_PL2303_H
+#define USBH_PL2303_H
+
+#include "usb_cdc.h"
+
+#define PL2303_SET_REQUEST             0x01
+#define PL2303_SET_REQUEST_PL2303HXN   0x80
+#define PL2303_SET_CRTSCTS             0x41
+#define PL2303_SET_CRTSCTS_PL2303X     0x61
+#define PL2303_SET_CRTSCTS_PL2303HXN   0xFA
+#define PL2303_CLEAR_CRTSCTS_PL2303HXN 0xFF
+#define PL2303_CRTSCTS_REG_PL2303HXN   0x0A
+#define PL2303_STATUS_REG_PL2303HX     0x8080
+
+/* Different PL2303 IC types */
+#define USBH_PL2303_TYPE_UNKNOWN   0
+#define USBH_PL2303_TYPE_PL2303    1
+#define USBH_PL2303_TYPE_PL2303HX  2
+#define USBH_PL2303_TYPE_PL2303HXD 3
+#define USBH_PL2303_TYPE_PL2303HXN 4
+
+struct usbh_pl2303 {
+    struct usbh_hubport *hport;
+    struct usb_endpoint_descriptor *bulkin;  /* Bulk IN endpoint */
+    struct usb_endpoint_descriptor *bulkout; /* Bulk OUT endpoint */
+
+    struct usbh_urb bulkout_urb;
+    struct usbh_urb bulkin_urb;
+
+    struct cdc_line_coding linecoding;
+
+    uint8_t intf;
+    uint8_t minor;
+    uint8_t chiptype;
+
+    void *user_data;
+};
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int usbh_pl2303_set_line_coding(struct usbh_pl2303 *pl2303_class, struct cdc_line_coding *line_coding);
+int usbh_pl2303_get_line_coding(struct usbh_pl2303 *pl2303_class, struct cdc_line_coding *line_coding);
+int usbh_pl2303_set_line_state(struct usbh_pl2303 *pl2303_class, bool dtr, bool rts);
+
+int usbh_pl2303_bulk_in_transfer(struct usbh_pl2303 *pl2303_class, uint8_t *buffer, uint32_t buflen, uint32_t timeout);
+int usbh_pl2303_bulk_out_transfer(struct usbh_pl2303 *pl2303_class, uint8_t *buffer, uint32_t buflen, uint32_t timeout);
+
+void usbh_pl2303_run(struct usbh_pl2303 *pl2303_class);
+void usbh_pl2303_stop(struct usbh_pl2303 *pl2303_class);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* USBH_PL2303_H */