switch-examples/usb/usbds/source/main.c

#include <string.h>
#include <stdio.h>
#include <malloc.h>

#include <switch.h>

//Example for usbds, see libnx usb.h. Switch-as-device<>host USB comms.
//Linux detects this as a serial device.
//Data transfer over USB works fine with this, however data isn't returned by "/dev/{device}" (depending on what is used for reading it) due to the header(?) from the device->host transfer not being valid.

Result usbds_test(u8 *tmpbuf)
{
	Result ret=0;
	s32 tmpindex=0;
	Handle usb_state_event;
	UsbDsInterface* interface = NULL;
	UsbDsEndpoint *endpoint_in = NULL, *endpoint_out = NULL;

	struct usb_interface_descriptor interface_descriptor = {
		.bLength = USB_DT_INTERFACE_SIZE,
		.bDescriptorType = USB_DT_INTERFACE,
		.bInterfaceNumber = USBDS_DEFAULT_InterfaceNumber,
                .bInterfaceClass = USB_CLASS_VENDOR_SPEC,
                .bInterfaceSubClass = USB_CLASS_VENDOR_SPEC,
                .bInterfaceProtocol = USB_CLASS_VENDOR_SPEC,
	};

	struct usb_endpoint_descriptor endpoint_descriptor_in = {
		.bLength = USB_DT_ENDPOINT_SIZE,
		.bDescriptorType = USB_DT_ENDPOINT,
		.bEndpointAddress = USB_ENDPOINT_IN,
                .bmAttributes = USB_TRANSFER_TYPE_BULK,
                .wMaxPacketSize = 0x40,
	};

	struct usb_endpoint_descriptor endpoint_descriptor_out = {
		.bLength = USB_DT_ENDPOINT_SIZE,
		.bDescriptorType = USB_DT_ENDPOINT,
		.bEndpointAddress = USB_ENDPOINT_OUT,
                .bmAttributes = USB_TRANSFER_TYPE_BULK,
                .wMaxPacketSize = 0x40,
	};

	usb_state_event = usbDsGetStateChangeEvent();

	//Setup interface.
        ret = usbDsGetDsInterface(&interface, &interface_descriptor, "usb");
	if(R_FAILED(ret))return ret;

	//Setup endpoints.
	ret = usbDsInterface_GetDsEndpoint(interface, &endpoint_in, &endpoint_descriptor_in);//device->host
	if(R_FAILED(ret))return ret;

	ret = usbDsInterface_GetDsEndpoint(interface, &endpoint_out, &endpoint_descriptor_out);//host->device
	if(R_FAILED(ret))return ret;

	ret = usbDsInterface_EnableInterface(interface);
	if(R_FAILED(ret))return ret;

	//Wait for usb comms init to start, which includes waiting for the usb cable to be inserted if it's not already.
	svcWaitSynchronization(&tmpindex, &usb_state_event, 1, U64_MAX);
	svcClearEvent(usb_state_event);

	svcSleepThread(5000000000);//The above will be signalled before the endpoints are ready for use, so just delay 5s (there's currently no known way to properly wait for endpoints-ready).

	memset(tmpbuf, 0, 0x1000);
	tmpbuf[0] = 0x11;
	tmpbuf[1] = 0x1;
	char *strptr = "Hello World!\n";
	strncpy((char*)&tmpbuf[2], strptr, 0x1000-2);

	//Start a device->host transfer.
	ret = usbDsEndpoint_PostBufferAsync(endpoint_in, tmpbuf, 2+strlen(strptr), NULL);
	if(R_FAILED(ret))return ret;
	//Wait for the transfer to finish.
	svcWaitSynchronization(&tmpindex, &endpoint_in->CompletionEvent, 1, U64_MAX);
	svcClearEvent(endpoint_in->CompletionEvent);

	//Start a host->device transfer.
	ret = usbDsEndpoint_PostBufferAsync(endpoint_out, tmpbuf, 0x200, NULL);
	if(R_FAILED(ret))return ret;

	//Wait for the transfer to finish.
	svcWaitSynchronization(&tmpindex, &endpoint_out->CompletionEvent, 1, U64_MAX);
	svcClearEvent(endpoint_out->CompletionEvent);

	memcpy(&tmpbuf[0x400], tmpbuf, 0x200-2);
	tmpbuf[0] = 0x11;
	tmpbuf[1] = 0x1;
	memcpy(&tmpbuf[2], &tmpbuf[0x400], 0x200-2);

	//Start a device->host transfer.
	ret = usbDsEndpoint_PostBufferAsync(endpoint_in, tmpbuf, 0x200, NULL);
	if(R_FAILED(ret))return ret;

	//Wait for the transfer to finish.
	svcWaitSynchronization(&tmpindex, &endpoint_in->CompletionEvent, 1, U64_MAX);
	svcClearEvent(endpoint_in->CompletionEvent);

	return 0;
}

int main(int argc, char **argv)
{
	Result ret;

	usbDsDeviceInfo deviceinfo = {
		.idVendor = 0x0403, // "Future Technology Devices International, Ltd"
		.idProduct = 0x6001, // "FT232 USB-Serial (UART) IC"
		.bcdDevice = 0x0200,
		.Manufacturer = "libnx",
		.Product = "usbds-example",
		.SerialNumber = "1337",
	};

	ret = usbDsInitialize(USBCOMPLEXID_Default, &deviceinfo);

	if (R_SUCCEEDED(ret)) {
		u8 *tmpbuf = memalign(0x1000, 0x1000);//The buffer for PostBufferAsync commands must be 0x1000-byte aligned.
		if(tmpbuf==NULL)ret = -4;

		if (R_SUCCEEDED(ret)) ret = usbds_test(tmpbuf);

		usbDsExit();
	}

        if(R_FAILED(ret))fatalSimple(ret);

	svcSleepThread(5000000000);//Delay 5s

	return 0;
}