Nut upsdev - Mar 2010 - new TSSHARA SOHO II ups

Hi all, My name is Sergio Penen and I'd like to contribute to the project by
developing a new driver for TS SHARA SOHO II usb ups.

I'm almost done decoding the protocol and already have some basic
functionality working with NUT. However I've some doubts on how to integrate
this driver with NUT and I wonder if you could give me some guidance in that
sense. To be more specific: In order to communicate with this UPS both input
and output have to be performed as USB interrupts I/O as this UPS doesn't
recognizes Control IO, so libusb_get_report() and libusb_set_report() will
not work. Looking at libusb.c I realized there's a libusb_get_interrupt()
which can be used to read from the endpoint, however there's no counterpart
libusb_set_interrupt() API and usb_communication_subdriver_t structure
doesn't contain a *set_interrupt element as well:

libusb.h
....
typedef struct usb_communication_subdriver_s {
        char *name;                             /* name of this
subdriver               */
        char *version;                          /* version of this
subdriver            */
        int (*open)(usb_dev_handle **sdevp,     /* try to open the next
available       */
                USBDevice_t *curDevice,         /* device matching
USBDeviceMatcher_t   */
                USBDeviceMatcher_t *matcher,
                int (*callback)(usb_dev_handle *udev, USBDevice_t *hd,
unsigned char *rdbuf, int rdlen));
        void (*close)(usb_dev_handle *sdev);
        int (*get_report)(usb_dev_handle *sdev, int ReportId, unsigned char
*raw_buf, int ReportSize );
        int (*set_report)(usb_dev_handle *sdev, int ReportId, unsigned char
*raw_buf, int ReportSize );
        int (*get_string)(usb_dev_handle *sdev, int StringIdx, char *buf,
size_t buflen);
        int (*get_interrupt)(usb_dev_handle *sdev, unsigned char *buf, int
bufsize, int timeout);
} usb_communication_subdriver_t;

My question is: Can I add a new element called *set_interrupt at the bottom
of usb_communication_subdriver_s struct ? I'm asking this because a change
on that structure will affect all USB drivers. Another obtion would be to
handle USB communication inside the driver itself...

Thanks,
Sergio.
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Citeren USUARIO INICIAL <spenen op ig.com.br>:
> My question is: Can I add a new element called *set_interrupt at the bottom
> of usb_communication_subdriver_s struct ?
No. Although some other drivers 'abuse' this (mainly for the open and  
close functions), this is not recommended.
> I'm asking this because a change on that structure will affect all USB
> drivers.
We certainly don't want that. The only things that you may wish to use  
from this structure is the open and close functions. These will be  
moved into usb-common.[ch] in the not so distant future. For the  
remainder of the communication read up on the usb_interrupt_read and  
usb_interrupt_write functions from the libusb-0.1 API:

     http://libusb.sourceforge.net/doc/functions.html
> Another obtion would be to handle USB communication inside the driver
> itself...
That would be a huge waste of effort, given the fact that libusb is  
widely available. Don't hesitate to post/discuss whatever you already  
have on the mailinglist.

Best regards, Arjen
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