Alan Cox wrote: >> hwmon is designed for slow I/O. It won't handle an ADC that does a few >> megasamples/sec. > > At that rate I would assume you want a memory mapped ring buffer or > similar not a sysfs style interface ? Agreed, this isn't going to do megsamps per second either (at least not without a fair bit faster processor / memory than available in embedded architectures). If you want to go at those rates you'll need something with a hardware ring buffer or an intermediate chip to provide said buffering whilst not trying to run a general purpose os at the same time. I am considering adding a 'burst' mode which would use up any available i2c / spi hardware buffers to get somewhere nearer to those sort of speeds. One of the most important elements of this subsystem is indeed a ring buffer architecture, currently not mmapped. I'm still trying to work out how to make that work without blocking the ring filling on interrupts. Currently I can only seem to get around this by doing copies of ring to mmapped locations and having some dirty bit type marking of regions that don't contain valid data. I guess suitable userspace libraries could hide this mess though. For the few ksps range the current chrdev interface is adequate if not ideal. The ring achitecture is one of the areas that probably needs most work. Thanks, -- Jonathan Cameron
