I was wondering if I could find the kernel codes for the spmv and conversions in CUSP library. I scanned the whole library but couldn't find it. Is that proprietary or something like that??
You didn't look to hard - the kernel source for every variant of spMV is in every CUSP version ever release (think about it, it is a header based template library...). You can see the device code for the different versions of spMV here.