On Thu, Sep 05, 2019 at 01:50:49PM -0500, Steve Maher wrote: > I've been googling and perusing the source tree, but am still unsure if > general bitbang support is present in flashrom. > > Specifically, I have a board which has an onboard FT2232H with some of the > GPIO pins wired to a SPI flash device. The pins used are NOT the MPSSE SPI > pins from the 2232, but rather some other unused GPIO pins (the MPSSE > dedicated pins are being used for JTAG, and the other 2232 channel is being > used for data transfer), and I can't change the wiring from the 2232 to the > SPI flash.
You're talking about the CBUS pins? > Does flashrom support this type of configuration? If there is general > bitbang support, I can write the necessary routines to control the pins of > the 2232 in a bitbang fashion. This sounds exactly how the developerbox_spi.c driver works. In that case the GPIO pins are hooked up to a CP2102N rather than an RT2232H but all the principles should be the same. Assuming the USB wire protocol is of the set pins/read pins variety (each a seperate USB transation) then things can work but it is extremely slow. Even after a bit of optimisation to make it easier to coalesce USB packets then my notes mention read performance roughly on par with a 2400 baud modem (between 60 and 70 minutes per megabyte if you prefer) and write performance was 50% slower still! > Any pointers here would be much appreciated. How do you hope to toggle the pins? Using libgpiod (e.g. use kernel-side FTDI driver and use the GPIO user/kernel interface) or via libftdi (e.g. userspace FTDI driver that uses the raw USB user/kernel interface). libgpiod is more generic but I think libftdi would be faster because it would be easier to coalesce USB packets. If you want to go via libftdi then perhaps try starting from the developerbox_spi.c driver, rip out the CP210XN code and replace it with libftdi calls to manipulate the CBUS pins. See https://github.com/legege/libftdi/blob/master/examples/bitbang_cbus.c for inspiration on that. Daniel. _______________________________________________ flashrom mailing list -- [email protected] To unsubscribe send an email to [email protected]
