I am trying to implement user space usb driver using libusb1.0.9. I have lpc2148 blueboard(ARM7) with me..This board is loaded with opensource USB stack/firmware by Mr. Bertrik Sikken. Now my user space driver is trying read write with board. I am getting garbage data. I want to know about the flow of bulk tranfer. For any transfer/transaction is there kernel device driver involved?? and do we need usb gadget device driver also?? I am not able to understand that where the data gets copied. Important thing is that when I read/write interrupt gets generated and I can see correct data on LCD. Do I need to read/write USBRxData/USBTxData? Please do the needfull.
I tried the below code for bulk transfer read and write..
int usb_read(struct libusb_device *dev,struct libusb_device_handle *hDevice)
{
char *data,*data1;
struct libusb_endpoint_descriptor *ep;
struct libusb_interface_descriptor *id;
int len=64,r,ret_alt,ret_clm,ret_rst,i;
struct libusb_device **list;
data = (char *)malloc(512); //allocation of buffers
data1 = (char *)malloc(512);
memset(data,'\0',512);
memset(data1,'\0',512);
if(hDevice==NULL)
{
printf("\nNO device found\n");
return 0;
}
int ret_open = libusb_open(dev,&hDevice);
if(ret_open!=0)
{
printf("Error in libusb_open\n");
libusb_free_device_list(list,1);
return -1;
}
char str_tx[512]="G"; //data to send to device
char str_rx[512]; //receive string
data = str_tx;
printf("data::%s\t,str::%s\n",data,str_tx);
//printf("%c\n",data);
ep = active_config(dev,hDevice);
printf("after ep\n");
//printf("alt_interface = %d\n",alt_interface);
ret_rst = libusb_reset_device(hDevice);
if(ret_rst < 0)
{
printf("Error in reset :: %d",ret_rst);
return -1;
}
printf("original data1 : %s\n",data1);
r = libusb_bulk_transfer(hDevice,0x08,str_tx,512,&len,0);
//write to device buffer from data
printf("Error number :: %d\n",r);
int le = ep->bEndpointAddress;
int ty = ep->bDescriptorType;
int y = ep->bmAttributes;
printf("y::%d\tatt:: %d\n",y,ep->bmAttributes);
if(r==-1)
printf("Error in io\n");
if(r==0)
{
printf("data returned :: %s\n",data);
printf("len= %d\n",len);
printf("Device Button Pressed!!!!\n");
}
else
{
printf("Error in bulk transfer\n");
return -1;
}
r = libusb_bulk_transfer(hDevice,0x82,data1,512,&len,0);
//read from device buffer to data1
//str_rx = data1;
//printf("End point address::%d\n",le);
//printf("End point desc.type::%d\n",ty);
if(r==-1)
printf("Error in io\n");
if(r==0)
{
printf("data1 returned::%s\n",data1); //received string in data1
printf("len= %d\n",len);
printf("Device Button Pressed!!!!\n");
}
else
{
printf("Error in bulk transfer\n");
return -1;
}
return 0;
}
Try the code given below and it should work on lpc2148. I have tested this with a lpc2148 configured to receive an interrupt from USB after a write happens (from user-space) and RTC starts running.
Answering to your question whether it involves kernel driver in read/write or not, as far as I have studied, You have to detach the kernel driver and claim the interface using libusb APIs. Though I am not sure whether it can be done without detaching it or not.
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <string.h>
#include </usr/local/include/libusb-1.0/libusb.h>
#define BULK_EP_OUT 0x82
#define BULK_EP_IN 0x08
int interface_ref = 0;
int alt_interface,interface_number;
int print_configuration(struct libusb_device_handle *hDevice,struct libusb_config_descriptor *config)
{
char *data;
int index;
data = (char *)malloc(512);
memset(data,0,512);
index = config->iConfiguration;
libusb_get_string_descriptor_ascii(hDevice,index,data,512);
printf("\nInterface Descriptors: ");
printf("\n\tNumber of Interfaces : %d",config->bNumInterfaces);
printf("\n\tLength : %d",config->bLength);
printf("\n\tDesc_Type : %d",config->bDescriptorType);
printf("\n\tConfig_index : %d",config->iConfiguration);
printf("\n\tTotal length : %lu",config->wTotalLength);
printf("\n\tConfiguration Value : %d",config->bConfigurationValue);
printf("\n\tConfiguration Attributes : %d",config->bmAttributes);
printf("\n\tMaxPower(mA) : %d\n",config->MaxPower);
free(data);
data = NULL;
return 0;
}
struct libusb_endpoint_descriptor* active_config(struct libusb_device *dev,struct libusb_device_handle *handle)
{
struct libusb_device_handle *hDevice_req;
struct libusb_config_descriptor *config;
struct libusb_endpoint_descriptor *endpoint;
int altsetting_index,interface_index=0,ret_active;
int i,ret_print;
hDevice_req = handle;
ret_active = libusb_get_active_config_descriptor(dev,&config);
ret_print = print_configuration(hDevice_req,config);
for(interface_index=0;interface_index<config->bNumInterfaces;interface_index++)
{
const struct libusb_interface *iface = &config->interface[interface_index];
for(altsetting_index=0;altsetting_index<iface->num_altsetting;altsetting_index++)
{
const struct libusb_interface_descriptor *altsetting = &iface->altsetting[altsetting_index];
int endpoint_index;
for(endpoint_index=0;endpoint_index<altsetting->bNumEndpoints;endpoint_index++)
{
const struct libusb_endpoint_desriptor *ep = &altsetting->endpoint[endpoint_index];
endpoint = ep;
alt_interface = altsetting->bAlternateSetting;
interface_number = altsetting->bInterfaceNumber;
}
printf("\nEndPoint Descriptors: ");
printf("\n\tSize of EndPoint Descriptor : %d",endpoint->bLength);
printf("\n\tType of Descriptor : %d",endpoint->bDescriptorType);
printf("\n\tEndpoint Address : 0x0%x",endpoint->bEndpointAddress);
printf("\n\tMaximum Packet Size: %x",endpoint->wMaxPacketSize);
printf("\n\tAttributes applied to Endpoint: %d",endpoint->bmAttributes);
printf("\n\tInterval for Polling for data Tranfer : %d\n",endpoint->bInterval);
}
}
libusb_free_config_descriptor(NULL);
return endpoint;
}
int main(void)
{
int r = 1;
struct libusb_device **devs;
struct libusb_device_handle *handle = NULL, *hDevice_expected = NULL;
struct libusb_device *dev,*dev_expected;
struct libusb_device_descriptor desc;
struct libusb_endpoint_descriptor *epdesc;
struct libusb_interface_descriptor *intdesc;
ssize_t cnt;
int e = 0,config2;
int i = 0,index;
char str1[64], str2[64];
char found = 0;
// Init libusb
r = libusb_init(NULL);
if(r < 0)
{
printf("\nfailed to initialise libusb\n");
return 1;
}
else
printf("\nInit Successful!\n");
// Get a list os USB devices
cnt = libusb_get_device_list(NULL, &devs);
if (cnt < 0)
{
printf("\nThere are no USB devices on bus\n");
return -1;
}
printf("\nDevice Count : %d\n-------------------------------\n",cnt);
while ((dev = devs[i++]) != NULL)
{
r = libusb_get_device_descriptor(dev, &desc);
if (r < 0)
{
printf("failed to get device descriptor\n");
libusb_free_device_list(devs,1);
libusb_close(handle);
break;
}
e = libusb_open(dev,&handle);
if (e < 0)
{
printf("error opening device\n");
libusb_free_device_list(devs,1);
libusb_close(handle);
break;
}
printf("\nDevice Descriptors: ");
printf("\n\tVendor ID : %x",desc.idVendor);
printf("\n\tProduct ID : %x",desc.idProduct);
printf("\n\tSerial Number : %x",desc.iSerialNumber);
printf("\n\tSize of Device Descriptor : %d",desc.bLength);
printf("\n\tType of Descriptor : %d",desc.bDescriptorType);
printf("\n\tUSB Specification Release Number : %d",desc.bcdUSB);
printf("\n\tDevice Release Number : %d",desc.bcdDevice);
printf("\n\tDevice Class : %d",desc.bDeviceClass);
printf("\n\tDevice Sub-Class : %d",desc.bDeviceSubClass);
printf("\n\tDevice Protocol : %d",desc.bDeviceProtocol);
printf("\n\tMax. Packet Size : %d",desc.bMaxPacketSize0);
printf("\n\tNo. of Configuraions : %d\n",desc.bNumConfigurations);
e = libusb_get_string_descriptor_ascii(handle, desc.iManufacturer, (unsigned char*) str1, sizeof(str1));
if (e < 0)
{
libusb_free_device_list(devs,1);
libusb_close(handle);
break;
}
printf("\nManufactured : %s",str1);
e = libusb_get_string_descriptor_ascii(handle, desc.iProduct, (unsigned char*) str2, sizeof(str2));
if(e < 0)
{
libusb_free_device_list(devs,1);
libusb_close(handle);
break;
}
printf("\nProduct : %s",str2);
printf("\n----------------------------------------");
if(desc.idVendor == 0xffff && desc.idProduct == 0x4)
{
found = 1;
break;
}
}//end of while
if(found == 0)
{
printf("\nDevice NOT found\n");
libusb_free_device_list(devs,1);
libusb_close(handle);
return 1;
}
else
{
printf("\nDevice found");
dev_expected = dev;
hDevice_expected = handle;
}
e = libusb_get_configuration(handle,&config2);
if(e!=0)
{
printf("\n***Error in libusb_get_configuration\n");
libusb_free_device_list(devs,1);
libusb_close(handle);
return -1;
}
printf("\nConfigured value : %d",config2);
if(config2 != 1)
{
libusb_set_configuration(handle, 1);
if(e!=0)
{
printf("Error in libusb_set_configuration\n");
libusb_free_device_list(devs,1);
libusb_close(handle);
return -1;
}
else
printf("\nDevice is in configured state!");
}
libusb_free_device_list(devs, 1);
if(libusb_kernel_driver_active(handle, 0) == 1)
{
printf("\nKernel Driver Active");
if(libusb_detach_kernel_driver(handle, 0) == 0)
printf("\nKernel Driver Detached!");
else
{
printf("\nCouldn't detach kernel driver!\n");
libusb_free_device_list(devs,1);
libusb_close(handle);
return -1;
}
}
e = libusb_claim_interface(handle, 0);
if(e < 0)
{
printf("\nCannot Claim Interface");
libusb_free_device_list(devs,1);
libusb_close(handle);
return -1;
}
else
printf("\nClaimed Interface\n");
active_config(dev_expected,hDevice_expected);
// Communicate
char *my_string, *my_string1;
int transferred = 0;
int received = 0;
int length = 0;
my_string = (char *)malloc(nbytes + 1);
my_string1 = (char *)malloc(nbytes + 1);
memset(my_string,'\0',64);
memset(my_string1,'\0',64);
strcpy(my_string,"prasad divesd");
length = strlen(my_string);
printf("\nTo be sent : %s",my_string);
e = libusb_bulk_transfer(handle,BULK_EP_IN,my_string,length,&transferred,0);
if(e == 0 && transferred == length)
{
printf("\nWrite successful!");
printf("\nSent %d bytes with string: %s\n", transferred, my_string);
}
else
printf("\nError in write! e = %d and transferred = %d\n",e,transferred);
sleep(3);
i = 0;
for(i = 0; i < length; i++)
{
e = libusb_bulk_transfer(handle,BULK_EP_OUT,my_string1,64,&received,0); //64 : Max Packet Lenght
if(e == 0)
{
printf("\nReceived: ");
printf("%c",my_string1[i]); //will read a string from lcp2148
sleep(1);
}
else
{
printf("\nError in read! e = %d and received = %d\n",e,received);
return -1;
}
}
e = libusb_release_interface(handle, 0);
libusb_close(handle);
libusb_exit(NULL);
printf("\n");
return 0;
}
To handle kernal detaching.
if(libusb_kernel_driver_active(dev_handle, 0) == 1) //find out if kernel driver is attached
{
cout << "Kernel Driver Active" << endl;
if(libusb_detach_kernel_driver(dev_handle, 0) == 0) //detach it
{
cout << "Kernel Driver Detached!" << endl;
}
}
来源：https://stackoverflow.com/questions/14769107/libusb-bulk-transfer