In linux kernel since version 2.6.29
(release Date: 2009-03-23)
This simple GPIO bitbanging SPI master uses the arch-neutral GPIO
interface to manage MOSI, MISO, SCK, and chipselect signals. SPI
slaves connected to a bus using this driver are configured as usual,
except that the spi_board_info.controller_data holds the GPIO number
for the chipselect used by this controller driver.
Note that this driver often won't achieve even 1 Mbit/sec speeds,
making it unusually slow for SPI. If your platform can inline
GPIO operations, you should be able to leverage that for better
speed with a custom version of this driver; see the source code.
interface to manage MOSI, MISO, SCK, and chipselect signals. SPI
slaves connected to a bus using this driver are configured as usual,
except that the spi_board_info.controller_data holds the GPIO number
for the chipselect used by this controller driver.
Note that this driver often won't achieve even 1 Mbit/sec speeds,
making it unusually slow for SPI. If your platform can inline
GPIO operations, you should be able to leverage that for better
speed with a custom version of this driver; see the source code.