The MCP3002 is a SPI chip.
The Linux SPI driver works.
It may be helpful if you add details of what you are doing.
If SPI is properly enabled the following devices will be visible in /dev.
$ ls -l /dev/spi*
crw-rw---T 1 root spi 153, 0 Jan 1 1970 /dev/spidev0.0
crw-rw---T 1 root spi 153, 1 Jan 1 1970 /dev/spidev0.1
$