Try the code given below and it should work on LPC2148. I have tested this with an LPC2148 configured to receive an interrupt from USB after a write happens (from user-space) and the RTC starts running.
Answering to your question whether it involves a 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("
Interface Descriptors: ");
printf("
Number of Interfaces: %d", config->bNumInterfaces);
printf("
Length: %d", config->bLength);
printf("
Desc_Type: %d", config->bDescriptorType);
printf("
Config_index: %d", config->iConfiguration);
printf("
Total length: %lu", config->wTotalLength);
printf("
Configuration Value: %d", config->bConfigurationValue);
printf("
Configuration Attributes: %d", config->bmAttributes);
printf("
MaxPower(mA): %d
", 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("
EndPoint Descriptors: ");
printf("
Size of EndPoint Descriptor: %d", endpoint->bLength);
printf("
Type of Descriptor: %d", endpoint->bDescriptorType);
printf("
Endpoint Address: 0x0%x", endpoint->bEndpointAddress);
printf("
Maximum Packet Size: %x", endpoint->wMaxPacketSize);
printf("
Attributes applied to Endpoint: %d", endpoint->bmAttributes);
printf("
Interval for Polling for data Tranfer: %d
", 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("
Failed to initialise libusb
");
return 1;
}
else
printf("
Init successful!
");
// Get a list of USB devices
cnt = libusb_get_device_list(NULL, &devs);
if (cnt < 0)
{
printf("
There are no USB devices on the bus
");
return -1;
}
printf("
Device count: %d
-------------------------------
", cnt);
while ((dev = devs[i++]) != NULL)
{
r = libusb_get_device_descriptor(dev, &desc);
if (r < 0)
{
printf("Failed to get device descriptor
");
libusb_free_device_list(devs, 1);
libusb_close(handle);
break;
}
e = libusb_open(dev, &handle);
if (e < 0)
{
printf("Error opening device
");
libusb_free_device_list(devs, 1);
libusb_close(handle);
break;
}
printf("
Device Descriptors: ");
printf("
Vendor ID: %x", desc.idVendor);
printf("
Product ID: %x", desc.idProduct);
printf("
Serial Number: %x", desc.iSerialNumber);
printf("
Size of Device Descriptor: %d", desc.bLength);
printf("
Type of Descriptor: %d", desc.bDescriptorType);
printf("
USB Specification Release Number: %d", desc.bcdUSB);
printf("
Device Release Number: %d", desc.bcdDevice);
printf("
Device Class: %d", desc.bDeviceClass);
printf("
Device Sub-Class: %d", desc.bDeviceSubClass);
printf("
Device Protocol: %d", desc.bDeviceProtocol);
printf("
Max. Packet Size: %d", desc.bMaxPacketSize0);
printf("
Number of Configurations: %d
", 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("
Manufactured: %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("
Product: %s", str2);
printf("
----------------------------------------");
if(desc.idVendor == 0xffff && desc.idProduct == 0x4)
{
found = 1;
break;
}
}//end of while
if(found == 0)
{
printf("
Device NOT found
");
libusb_free_device_list(devs, 1);
libusb_close(handle);
return 1;
}
else
{
printf("
Device found");
dev_expected = dev;
hDevice_expected = handle;
}
e = libusb_get_configuration(handle, &config2);
if(e!=0)
{
printf("
***Error in libusb_get_configuration
");
libusb_free_device_list(devs, 1);
libusb_close(handle);
return -1;
}
printf("
Configured value: %d", config2);
if(config2 != 1)
{
libusb_set_configuration(handle, 1);
if(e!=0)
{
printf("Error in libusb_set_configuration
");
libusb_free_device_list(devs, 1);
libusb_close(handle);
return -1;
}
else
printf("
Device is in configured state!");
}
libusb_free_device_list(devs, 1);
if(libusb_kernel_driver_active(handle, 0) == 1)
{
printf("
Kernel Driver Active");
if(libusb_detach_kernel_driver(handle, 0) == 0)
printf("
Kernel Driver Detached!");
else
{
printf("
Couldn't detach kernel driver!
");
libusb_free_device_list(devs, 1);
libusb_close(handle);
return -1;
}
}
e = libusb_claim_interface(handle, 0);
if(e < 0)
{
printf("
Cannot Claim Interface");
libusb_free_device_list(devs, 1);
libusb_close(handle);
return -1;
}
else
printf("
Claimed Interface
");
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, '', 64);
memset(my_string1, '', 64);
strcpy(my_string, "Prasad Divesd");
length = strlen(my_string);
printf("
To be sent: %s", my_string);
e = libusb_bulk_transfer(handle, BULK_EP_IN, my_string, length, &transferred, 0);
if(e == 0 && transferred == length)
{
printf("
Write successful!");
printf("
Sent %d bytes with string: %s
", transferred, my_string);
}
else
printf("
Error in write! e = %d and transferred = %d
", 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 Length
if(e == 0)
{
printf("
Received: ");
printf("%c", my_string1[i]); //Will read a string from LPC2148
sleep(1);
}
else
{
printf("
Error in read! e = %d and received = %d
", e, received);
return -1;
}
}
e = libusb_release_interface(handle, 0);
libusb_close(handle);
libusb_exit(NULL);
printf("
");
return 0;
}