148 lines
8.2 KiB
C
148 lines
8.2 KiB
C
#ifndef _usb_operations_h
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#define _usb_operations_h
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <assert.h>
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#include <errno.h>
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#include <libusb.h>
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//list of included dictionaries for defining request, wValue, and wIndex fields
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#include "shared_dictionaries.h"
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//uncomment to DEBUG this file alone
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//#define DEBUG
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//"make debug" to get DEBUG msgs on entire program
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#include "dbg.h"
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//control transfer request types
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//uint8_t libusb_control_setup::bmRequestType
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//Request type.
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// Bits 0:4 determine recipient, see libusb_request_recipient. Bits 5:6 determine type, see libusb_request_type. Bit 7 determines data transfer direction, see libusb_endpoint_direction.
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//
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//libusb_request_types:
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//LIBUSB_REQUEST_TYPE_STANDARD Standard handled by driver during setup/etc
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//LIBUSB_REQUEST_TYPE_CLASS Class for use with specific device classes like HID.
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//LIBUSB_REQUEST_TYPE_VENDOR Vendor application specific as we choose which is what we'll be utilizing for all transfers
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//LIBUSB_REQUEST_TYPE_RESERVED Reserved.
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//
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//libusb_request_recipients:
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//LIBUSB_RECIPIENT_DEVICE Device.
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//LIBUSB_RECIPIENT_INTERFACE Interface.
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//LIBUSB_RECIPIENT_ENDPOINT Endpoint.
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//LIBUSB_RECIPIENT_OTHER Other.
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//
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//LIBUSB_ENDPOINT_IN 0x80 In: device-to-host.
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//LIBUSB_ENDPOINT_OUT 0x00 Out: host-to-device.
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#define USB_IN LIBUSB_ENDPOINT_IN
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#define USB_OUT LIBUSB_ENDPOINT_OUT
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//USB timeout
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#define TIMEOUT_1_SEC 1000
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#define TIMEOUT_5_SEC 5000
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//Max transfer length
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#define MAX_VUSB 245 //Max VUSB transfers without long transfers enabled
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#define USB_NO_MSG 255 //designates transfer with no message
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#define MAX_VUSB_LONGXFR 16384 //16KByte biggest value 16bit wLength can hold
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//typedef struct USBtransfer {
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//This is the primary USB request struct used by host app used for all application USB communications.
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//handle is retrieved from open_usb_device gives us a means to point to the opened USB device.
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//The remaining elements are all directly fed to the outgoing USB setup & data packets to/from the device.
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// Every USB transfer starts with host sending one of these setup packets to the device.
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// the setup packets are unidirectinal always coming from the bus master (host).
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// The data packet(s) for the transfer then follow and are bidirectional.
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// The drivers handle final NACK/ACK/STALL packet for the most part..
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// Note V-USB mcu driver doesn't have time to check CRC so it sends ACK assuming no corruption.
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//endpoint basically this is the direction of the data packet to follow.
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// the usb device has a OUT and IN endpoint buffer and this defines which is being accessed.
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// OUT "out of host" is for writting data to the usb device.
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// IN "in to host" is for reading data from the usb device.
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// endpoint is the only portion of setup packet's requestType field that isn't hardcoded.
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// Vendor request types used exclusively as they meet the our intent and 'hard coded' into this struct.
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// The recipient of this setup packet is also 'hard coded' to the usb device.
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//request is more like request type in this scope and designates the 'dictionary' containing the command.
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// pinport is the first dictionary of commands, more to come as things develop.
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// these requests/dictionaries define how the wValue and wIndex fields are utilized.
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// anything can be placed in the 4 bytes of wValue/wIndex as defined by the dictionary.
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//wValueMSB:wValueLSB
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// This is where the app places the 'command' being given to the retro programmer.
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// LSB is big enough for now and contains the actual opcode.
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// MSB is used as an overflow for operands/data if wIndex is not large enough.
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// future dicts with more than 256 opcodes could define some/all of MSB to contain the opcode as well.
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//wIndexMSB:wIndexLSB
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// This typically contains the operand/data for the opcode but could be used for anything
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// as defined by the opcode. Raw buffer data could even be placed here to cheat the 254 Byte transfer
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// limit of V-USB (w/o long xfrs), the two bytes of wIndex bring to full page of 256 Bytes.
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// Planning for this to contain the page index (aka memory addr) of the transmitted data buffer.
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//wLength must be set to the size of the data transfer to follow this setup packet in Bytes.
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// if wLength is >8, drivers split data into 8byte packets and final packet of < 8Bytes if needed.
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// with 16bit wLength 16KB transfers are largest possible, requires using long xfrs on device driver.
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// The max length without long xfrs is 254Bytes, value 255 is reserved for USB_NO_MSG.
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// This means wLength's MSByte is under utilized but prob shouldn't concern ourselves with that.
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//data is a pointer to the data buffer being sent for writes (OUT transfers).
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// read (IN transfers) utilize data pointer to pass location of where to dump read data.
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typedef struct USBtransfer {
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libusb_device_handle *handle;
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uint8_t endpoint;
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uint8_t request;
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uint8_t wValueMSB;
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uint8_t wValueLSB;
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uint8_t wIndexMSB;
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uint8_t wIndexLSB;
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uint16_t wLength;
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unsigned char *data;
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} USBtransfer;
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libusb_device_handle * open_usb_device( libusb_context *context );
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void close_usb(libusb_context *context, libusb_device_handle *handle);
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//int libusb_control_transfer (libusb_device_handle *dev_handle, uint8_t bmRequestType, uint8_t bRequest, uint16_t wValue, uint16_t wIndex, unsigned char *data, uint16_t wLength, unsigned int timeout)
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//
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//SETUP PACKET FIELDS:
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//bmRequestType: ORing of req type (STD/VENDOR), recipient (think we only care about DEVICE), endpoint direction IN-dev->host OUT-host->dev
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//bRequest: single byte that can signify any 'command' or 'request' we setup.
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//The wValue and wIndex fields allow parameters to be passed with the request. Think we can do whatever we want with these
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//wLength is used the specify the number of bytes to be transferred should there be a data phase.
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//wLength the length field for the setup packet. The data buffer should be at least this size.
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// USB 1.1 low speed standard limits to 8 bytes
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// V-USB seems to break this limit with max of 254 bytes (255 designates "USB_NO_MSG"
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// V-USB allows "LONG TRANSFERS" utilizing full 16bit wLength for upto 16384 bytes = exactly 16KBytes
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// although considering sram on AVR doesn't explode with long transfers and read/write functions are in 8byte chunks,
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// I think it really is limited to 8bytes
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// One idea to squeeze more data is have a request type defined that utilizes wValue and wIndex to gain 4bytes + 8buffer = 12bytes 50% gain
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// Not sure how to gain access to wValue/wIndex with vusb drivers...
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// answer: usbFunctionSetup will get called for every setup packet and pass all 8 bytes of setup packet
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// Can ultimately answer this question by counting how many startup packets are recieved by usbFunciton setup for transfers >8 bytes
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// If when sending >8 byte control transfers, a setup packet only comes once, then there is nothing to abuse
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// however if the same setup packet gets sent for every 8 bytes, it would be better to only perform 8byte transfers and stuff
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// 4 more bytes in wValue and wIndex fields to increase throughput by ~50%!!!
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// Testing shows that usbFunctionSetup only gets called once for transfers of 254 bytes
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// So there is only one setup packet for multiple data packets of 8bytes each
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//
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//Still not sure increasing transfer length doesn't simply break up into bunch of small 8byte transfers although it doesn't sound like it.
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//245byte limit is kind of a pain.. but wValue/wIndex fields could be abused to send 256 bytes
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//Long transfers apparently max out speed @ 24KBps with 300 bytes: https://forums.obdev.at/viewtopic.php?t=3059
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//
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//PAYLOAD:
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//data: a suitably-sized data buffer for either input or output (depending on direction bits within bmRequestType)
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//
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//TIMEOUT:
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//timeout: (in millseconds) that this function should wait before giving up due to no response being received.
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// For an unlimited timeout, use value 0
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// USB nutshell: A compliant host requires control transfer response within 5sec
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//
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//RETURN:
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// Returns on success, the number of bytes actually transferred
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// LIBUSB_ERROR_TIMEOUT if the transfer timed out
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// LIBUSB_ERROR_PIPE if the control request was not supported by the device
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// LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
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// another LIBUSB_ERROR code on other failures
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int usb_transfer( USBtransfer *transfer );
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#endif
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