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Linux---应用层获取usb设备描述信息&通过endpoint地址数据通讯
🌈应用层获取USB设备信息总体思路
应用层可以打开USB设备的节点，读取包括USB设备的配置，端口，端点等信息。具体来说对于USB设备均存在对应的
VID PID，其中VID指的是Vendor ID（厂商识别码），用于唯一标识USB设备的制造商。PID指的是Product ID（产品识别码），用于唯一标识USB设备的产品型号。通过VID和PID，可以确定一个具体的USB设备，因为每个设备的VID和PID是唯一的，可以帮助系统识别和与设备进行交互。
如果上位机正常识别USB设备，我们可以通过对应节点信息
/sys/bus/usb/devices按照文件目录去搜索，如果目录中idVendor和idProduct与我们要搜索的一致，可以判定为我们需要找的设备节点。如下图1-4目录中的idVendor和idProduct与我们要找寻的一致：root@Vostro:/sys/bus/usb/devices/1-4# ls -al total 0 drwxr-xr-x 12 root root 0 Aug 31 20:55 . drwxr-xr-x 8 root root 0 Aug 10 11:55 .. drwxr-xr-x 6 root root 0 Aug 31 20:55 1-4:1.0 drwxr-xr-x 6 root root 0 Aug 31 20:55 1-4:1.1 drwxr-xr-x 7 root root 0 Aug 31 20:55 1-4:1.2 drwxr-xr-x 7 root root 0 Aug 31 20:55 1-4:1.3 drwxr-xr-x 7 root root 0 Aug 31 20:55 1-4:1.4 drwxr-xr-x 7 root root 0 Aug 31 20:55 1-4:1.5 drwxr-xr-x 7 root root 0 Aug 31 20:55 1-4:1.6 -rw-r--r-- 1 root root 4096 Aug 31 20:55 authorized -rw-r--r-- 1 root root 4096 Aug 31 20:55 avoid_reset_quirk -r--r--r-- 1 root root 4096 Aug 31 20:55 bcdDevice -rw-r--r-- 1 root root 4096 Aug 31 20:55 bConfigurationValue -r--r--r-- 1 root root 4096 Aug 31 20:55 bDeviceClass -r--r--r-- 1 root root 4096 Aug 31 20:55 bDeviceProtocol -r--r--r-- 1 root root 4096 Aug 31 20:55 bDeviceSubClass -r--r--r-- 1 root root 4096 Aug 31 20:55 bmAttributes -r--r--r-- 1 root root 4096 Aug 31 20:55 bMaxPacketSize0 -r--r--r-- 1 root root 4096 Aug 31 20:55 bMaxPower -r--r--r-- 1 root root 4096 Aug 31 20:55 bNumConfigurations -r--r--r-- 1 root root 4096 Aug 31 20:55 bNumInterfaces -r--r--r-- 1 root root 4096 Aug 31 20:55 busnum -r--r--r-- 1 root root 4096 Aug 31 20:55 configuration -r--r--r-- 1 root root 65553 Aug 31 20:55 descriptors -r--r--r-- 1 root root 4096 Aug 31 20:55 dev -r--r--r-- 1 root root 4096 Aug 31 20:55 devnum -r--r--r-- 1 root root 4096 Aug 31 20:55 devpath lrwxrwxrwx 1 root root 0 Aug 31 20:55 driver -> ../../../../../bus/usb/drivers/usb drwxr-xr-x 3 root root 0 Aug 31 20:55 ep_00 lrwxrwxrwx 1 root root 0 Aug 31 20:55 firmware_node -> ../../../../LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:4c/device:4d/device:51 -r--r--r-- 1 root root 4096 Aug 31 20:55 idProduct -r--r--r-- 1 root root 4096 Aug 31 20:55 idVendor -r--r--r-- 1 root root 4096 Aug 31 20:55 ltm_capable -r--r--r-- 1 root root 4096 Aug 31 20:55 manufacturer -r--r--r-- 1 root root 4096 Aug 31 20:55 maxchild drwxr-xr-x 2 root root 0 Aug 31 20:55 physical_location lrwxrwxrwx 1 root root 0 Aug 31 20:55 port -> ../1-0:1.0/usb1-port4 drwxr-xr-x 2 root root 0 Aug 31 20:55 power -r--r--r-- 1 root root 4096 Aug 31 20:55 product -r--r--r-- 1 root root 4096 Aug 31 20:55 quirks -r--r--r-- 1 root root 4096 Aug 31 20:55 removable --w------- 1 root root 4096 Aug 31 20:55 remove -r--r--r-- 1 root root 4096 Aug 31 20:55 rx_lanes -r--r--r-- 1 root root 4096 Aug 31 20:55 serial -r--r--r-- 1 root root 4096 Aug 31 20:55 speed lrwxrwxrwx 1 root root 0 Aug 31 20:55 subsystem -> ../../../../../bus/usb -r--r--r-- 1 root root 4096 Aug 31 20:55 tx_lanes -rw-r--r-- 1 root root 4096 Aug 31 20:55 uevent -r--r--r-- 1 root root 4096 Aug 31 20:55 urbnum -r--r--r-- 1 root root 4096 Aug 31 20:55 version- 1
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在找到对应目录后，读取该目录下面的
uevent节点，会获取到该USB设备对应的主设备号，次设备号，设备名称、设备类型等相关信息，如下图：root@Vostro:/sys/bus/usb/devices/1-4# cat uevent MAJOR=189 MINOR=115 DEVNAME=bus/usb/001/116 DEVTYPE=usb_device DRIVER=usb PRODUCT=2cb7/1/100 TYPE=0/0/0 BUSNUM=001 DEVNUM=116- 1
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这里我们需要获取的是
DEVNAME=bus/usb/001/116这个信息，该信息表示在/dev设备目录下/dev/bus/usb/001/116为该USB设备的节点，我们后续读取USB设备信息以及数据读写操作都是通过这个节点进行的，如下图我们可以看到/dev/bus/usb/001/目录下有多个USB设备，其中116为我们需要的设备节点：root@Vostro:/sys/bus/usb/devices/1-4# cd /dev/bus/usb/001/ root@Vostro:/dev/bus/usb/001# ls -al total 0 drwxr-xr-x 2 root root 120 Sep 1 17:59 . drwxr-xr-x 4 root root 80 Aug 10 11:55 .. crw-rw-rw- 1 root root 189, 0 Aug 10 11:56 001 crw-rw-rw- 1 root root 189, 2 Aug 10 11:56 003 crw-rw-rw- 1 root root 189, 3 Aug 10 11:56 004 crw-rw-rw- 1 root root 189, 115 Aug 31 20:55 116- 1
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找到该节点后，通过应用层的
open函数打开设备，通过read函数读取并解析设备的相关信息，即可获得USB设备的配置，端点，端口等信息。
🌈应用层代码实例
#include#include #include #include #include #include #include #include #include #include #define BUF_SIZE 512 #define MAX_PATH_LEN 512 #define USB_DIR_BASE "/sys/bus/usb/devices" typedef struct { int idVendor; int idProduct; int InterfaceNum; int usbdev; char portname[BUF_SIZE]; char syspath[BUF_SIZE]; char busname[BUF_SIZE]; int bulk_ep_in; int bulk_ep_out; int wMaxPacketSize; int usb_need_zero_package; int (* write)(const void *handle, void *pbuf, int size, int portnum); int (* read)(const void *handle, void *pbuf, int size, int portnum); } s_usbdev_t; s_usbdev_t udev; int strStartsWith(const char *str, const char *match_str) { for ( ; *str != '\0' && *match_str != '\0'; str++, match_str++) { if (*str != *match_str) { return 0; } } return *match_str == '\0'; } static int get_usbsys_val(const char *sys_filename, int base) { char buff[64] = {0}; int ret_val = -1; int fd = open(sys_filename, O_RDONLY); if (fd < 0) { return -1; } if (read(fd, buff, sizeof(buff)) <= 0) { printf("read:%s failed\n", sys_filename); } else { ret_val = strtoul(buff, NULL, base); } close(fd); return ret_val; } static int get_busname_by_uevent(const char *uevent, char *busname) { FILE *fp = NULL; char line[BUF_SIZE] = {0}; int MAJOR = 0, MINOR = 0; char DEVTYPE[64] = {0}, PRODUCT[64] = {0}; fp = fopen(uevent, "r"); if (fp == NULL) { printf("fopen %s failed, errno:%d(%s)\n", uevent, errno, strerror(errno)); return -1; } while (fgets(line, sizeof(line), fp)) { if (line[strlen(line) - 1] == '\n' || line[strlen(line) - 1] == '\r') { line[strlen(line) - 1] = 0; } if (strStartsWith(line, "MAJOR=")) { MAJOR = atoi(&line[strlen("MAJOR=")]); } else if (strStartsWith(line, "MINOR=")) { MINOR = atoi(&line[strlen("MINOR=")]); } else if (strStartsWith(line, "DEVICE=")) { strncpy(busname, &line[strlen("DEVICE=")], MAX_PATH_LEN); } else if (strStartsWith(line, "DEVNAME=")) { strncpy(busname, &line[strlen("DEVNAME=")], MAX_PATH_LEN); } else if (strStartsWith(line, "DEVTYPE=")) { strncpy(DEVTYPE, &line[strlen("DEVTYPE=")], sizeof(DEVTYPE)); } else if (strStartsWith(line, "PRODUCT=")) { strncpy(PRODUCT, &line[strlen("PRODUCT=")], sizeof(PRODUCT)); } } fclose(fp); if (MAJOR != 189 || MINOR == 0 || busname[0] == 0 || DEVTYPE[0] == 0 || PRODUCT[0] == 0 || strStartsWith(DEVTYPE, "usb_device") == 0) { return -1; } return 0; } int usb_dev_open(int usb_vid, int usb_pid) { char devdesc[MAX_PATH_LEN*2] = {0}; char devname[MAX_PATH_LEN+128] = {0}; size_t desc_length = 0, len = 0; int bInterfaceNumber = 0; DIR *usbdir = NULL; struct dirent *dent = NULL; int idVendor = 0, idProduct = 0; int bNumInterfaces = 0, bConfigurationValue = 0; char sys_filename[MAX_PATH_LEN] = {0}; usbdir = opendir("/sys/bus/usb/devices"); if (usbdir == NULL) { return -1; } while ((dent = readdir(usbdir)) != NULL) { if (strcmp(dent->d_name, ".") == 0 || strcmp(dent->d_name, "..") == 0) { continue; } snprintf(sys_filename, sizeof(sys_filename), "%s/%s/idVendor", USB_DIR_BASE, dent->d_name); if ((idVendor = get_usbsys_val(sys_filename, 16)) <= 0) { continue; } snprintf(sys_filename, sizeof(sys_filename), "%s/%s/idProduct", USB_DIR_BASE, dent->d_name); if ((idProduct = get_usbsys_val(sys_filename, 16)) <= 0) { continue; } snprintf(sys_filename, sizeof(sys_filename), "%s/%s/bConfigurationValue", USB_DIR_BASE, dent->d_name); if ((bConfigurationValue = get_usbsys_val(sys_filename, 10)) <= 0) { continue; } snprintf(sys_filename, sizeof(sys_filename), "%s/%s/bNumInterfaces", USB_DIR_BASE, dent->d_name); if ((bNumInterfaces = get_usbsys_val(sys_filename, 10)) <= 0) { continue; } if((idVendor == usb_vid)&&(idProduct == usb_pid)) { udev.idVendor = idVendor; udev.idProduct = idProduct; printf("----------------------------------\n"); printf("idVendor: %04x\n", udev.idVendor); printf("idProduct: %04x\n", udev.idProduct); printf("bNumInterfaces: %d\n", bNumInterfaces); printf("bConfigurationValue: %d\n", bConfigurationValue); snprintf(sys_filename, sizeof(sys_filename), "%s/%s/uevent", USB_DIR_BASE, dent->d_name); get_busname_by_uevent(sys_filename, udev.busname); printf("busname: %s\n", udev.busname); printf("----------------------------------\n"); break; } usleep(10000); } if (usbdir) { closedir(usbdir); usbdir = NULL; } snprintf(devname, sizeof(devname), "/dev/%s", udev.busname); if (access(devname, F_OK | R_OK| W_OK)) { printf("access %s failed, errno:%d(%s)\n", devname, errno, strerror(errno)); return -1; } udev.usbdev = open(devname, O_RDWR | O_NOCTTY); if (udev.usbdev < 0) { printf("open %s failed, errno:%d(%s)\n", devname, errno, strerror(errno)); return -1; } printf("[%s] OK.\n", devname); desc_length = read(udev.usbdev, devdesc, sizeof(devdesc)); printf("desc_length is %zu,read length is %zu\r\n", sizeof(devdesc), desc_length); for (len=0; len<desc_length;) { struct usb_descriptor_header *h = (struct usb_descriptor_header *)(devdesc + len); if (h->bLength == sizeof(struct usb_device_descriptor) && h->bDescriptorType == USB_DT_DEVICE) { struct usb_device_descriptor *device = (struct usb_device_descriptor *)h; printf("P: idVendor: %04x idProduct:%04x\n", device->idVendor, device->idProduct); } else if (h->bLength == sizeof(struct usb_config_descriptor) && h->bDescriptorType == USB_DT_CONFIG) { struct usb_config_descriptor *config = (struct usb_config_descriptor *)h; printf("C: bNumInterfaces: %d\n", config->bNumInterfaces); } else if (h->bLength == sizeof(struct usb_interface_descriptor) && h->bDescriptorType == USB_DT_INTERFACE) { struct usb_interface_descriptor *interface = (struct usb_interface_descriptor *)h; printf("I: If#= %d Alt= %d #EPs= %d Cls=%02x Sub=%02x Prot=%02x\n", interface->bInterfaceNumber, interface->bAlternateSetting, interface->bNumEndpoints, interface->bInterfaceClass, interface->bInterfaceSubClass, interface->bInterfaceProtocol); bInterfaceNumber = interface->bInterfaceNumber; } else if (h->bLength == USB_DT_ENDPOINT_SIZE && h->bDescriptorType == USB_DT_ENDPOINT) { struct usb_endpoint_descriptor *endpoint = (struct usb_endpoint_descriptor *)h; if ( (endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) == USB_ENDPOINT_XFER_BULK) { if (endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK) { udev.bulk_ep_in = endpoint->bEndpointAddress; printf("bulk_ep_in:0x%02X\n", udev.bulk_ep_in); } else { udev.bulk_ep_out = endpoint->bEndpointAddress; printf("bulk_ep_out:0x%02X\n", udev.bulk_ep_out); } udev.wMaxPacketSize = endpoint->wMaxPacketSize; printf("wMaxPacketSize:%d\n", endpoint->wMaxPacketSize); } } len += h->bLength; } return 0; } int main(int argc, char * * argv) { int vid_hex,pid_hex; if(argc !=3 ) { printf("Usage: usb_read_device_info USB_VID USB_PID \r\n"); return -1; } sscanf(argv[1], "%x", &vid_hex); sscanf(argv[2], "%x", &pid_hex); printf("USB VID %4x, PID is %4x\r\n", vid_hex, pid_hex); usb_dev_open(vid_hex,pid_hex); } - 1
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🌈实例测试
插入一个VID PID为2cb7 0001的USB设备，运行上面的测试程序（编译过程省略），main函数入口参数传入
VID 2CB7及 PID 0001运行如下：book@Vostro:~/Joy/Test$ sudo ./USB_read_device_info 2cb7 0001 USB VID 2cb7, PID is 1 ---------------------------------- idVendor: 2cb7 idProduct: 0001 bNumInterfaces: 7 bConfigurationValue: 1 busname: bus/usb/001/116 ---------------------------------- [/dev/bus/usb/001/116] OK. desc_length is 1024,read length is 221 P: idVendor: 2cb7 idProduct:0001 C: bNumInterfaces: 7 I: If#= 0 Alt= 0 #EPs= 1 Cls=02 Sub=06 Prot=00 I: If#= 1 Alt= 0 #EPs= 0 Cls=0a Sub=00 Prot=00 I: If#= 1 Alt= 1 #EPs= 2 Cls=0a Sub=00 Prot=00 bulk_ep_in:0x81 wMaxPacketSize:512 bulk_ep_out:0x01 wMaxPacketSize:512 I: If#= 2 Alt= 0 #EPs= 2 Cls=ff Sub=ff Prot=ff bulk_ep_in:0x82 wMaxPacketSize:512 bulk_ep_out:0x02 wMaxPacketSize:512 I: If#= 3 Alt= 0 #EPs= 2 Cls=ff Sub=ff Prot=ff bulk_ep_in:0x83 wMaxPacketSize:512 bulk_ep_out:0x03 wMaxPacketSize:512 I: If#= 4 Alt= 0 #EPs= 2 Cls=ff Sub=ff Prot=ff bulk_ep_in:0x84 wMaxPacketSize:512 bulk_ep_out:0x04 wMaxPacketSize:512 I: If#= 5 Alt= 0 #EPs= 2 Cls=ff Sub=ff Prot=ff bulk_ep_in:0x85 wMaxPacketSize:512 bulk_ep_out:0x05 wMaxPacketSize:512 I: If#= 6 Alt= 0 #EPs= 2 Cls=ff Sub=42 Prot=01 bulk_ep_in:0x86 wMaxPacketSize:512 bulk_ep_out:0x06 wMaxPacketSize:512- 1
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可以看到通过解析read函数读取的相关信息，打印出了该
USB设备的configuration、interface、endpoint等信息。🌈应用层通过endpoint进行数据读写
使用
USB的endpoint进行数据读写，需要了解每个endpoint的地址，并且endpoint为单向的，对于USB设备每interface下面可以有多个endpoint，这些endpoint可以是输入，也可以是输出，下面实例的设备节点USB_DEV_PATH是由上面应用程序获取，通讯具体的endpoint地址也是由上面应用程序获取，这里直接写死对应数值以便测试：#include#include #include #include #include #include #include #include // USB设备节点路径，可通过上部分应用层实例代码获取某VID PID 对应的usb设备节点 #define USB_DEV_PATH "/dev/bus/usb/001/018" int usbfs_bulk_write(int fd, char *data, size_t dataLen) { int ret; struct usbdevfs_urb urb_write; struct usbdevfs_urb *urb = NULL; memset(&urb_write, 0, sizeof(urb_write)); urb_write.type = USBDEVFS_URB_TYPE_BULK; urb_write.endpoint = 0x05; urb_write.status = -1; urb_write.buffer = (void *)data; urb_write.buffer_length = dataLen; urb_write.usercontext = &urb_write; printf("endpoint is %d, buffer_length is %d\r\n", urb_write.endpoint, urb_write.buffer_length); do { ret = ioctl(fd, USBDEVFS_SUBMITURB, &urb_write); } while ((ret < 0) && (errno == EINTR)); if (ret != 0) { printf("USBDEVFS_SUBMITURB failed, ret: %d, errno:%d(%s)\n", ret, errno, strerror(errno)); return -1; } do { urb = NULL; ret = ioctl(fd, USBDEVFS_REAPURB, &urb); } while ((ret < 0) && (errno == EINTR)); if (ret == 0 && urb && urb->status == 0 && urb->actual_length) { return urb->actual_length; } return -1; } int usbfs_bulk_read(int fd, char *data, size_t dataLen) { int ret = -1; struct usbdevfs_bulktransfer bulk; bulk.ep = 0x85; bulk.len = dataLen; bulk.data = data; bulk.timeout = 3000; do { ret = ioctl(fd, USBDEVFS_BULK, &bulk); } while ((ret < 0) && (errno == EINTR)); return ret; } int main() { // 准备要写入的数据 unsigned char data[] = {0x01,0xaa,0xaa,0xaa,0x01,0x55,0x73,0x01,0x14,0x00,0x00,0x00,0x06,0x67,0xbb,0xbb,0x04, 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x03,0x00,0x00,0x00,0x44,0x09,0x7e}; size_t dataLen = sizeof(data); int ret; int fd = open(USB_DEV_PATH, O_RDWR | O_NOCTTY); // 打开USB设备文件描述符 if (fd == -1) { perror("Failed to open USB device"); return -1; } ret = usbfs_bulk_write(fd, data, dataLen); printf("usbfs_bulk_write ret is %d\r\n", ret); ret = usbfs_bulk_read(fd, data, dataLen); printf("usbfs_bulk_read ret is %d\r\n", ret); return 0; } - 1
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上述代码实际测试结果如下：
root:/home/Joy/Test# ./usb_bulk_write_read endpoint is 5, buffer_length is 35 usbfs_bulk_write ret is 35 usbfs_bulk_read ret is 10- 1
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- 原文地址：https://blog.csdn.net/lihuan680680/article/details/132348084
