CREG GPIO is a driver for weird soc-specific output ports, which are controlled by some fields in memory mapped register.
Example:
31 9 7 5 0 < bit number | | | | | [ not used | gpio-1 | gpio-0 | <-shift-> ] < 32 bit register ^ ^ | | write 0x2 == set output to "1" (activate) write 0x3 == set output to "0" (deactivate)
As of tooday we only support fixed (hardcoded) bit per gpio line, activate / deactivatei and shift values. Fix that by read them from device tree to be able to use this driver for other boards.
Eugeniy Paltsev (2): GPIO: CREG: improve flexibility of hsdk-creg-gpio driver CREG GPIO: add device tree bindings
MAINTAINERS | 1 + arch/arc/dts/hsdk.dts | 7 +- doc/device-tree-bindings/gpio/snps,creg-gpio.txt | 43 ++++++++++ drivers/gpio/hsdk-creg-gpio.c | 103 ++++++++++++++++++----- 4 files changed, 131 insertions(+), 23 deletions(-) create mode 100644 doc/device-tree-bindings/gpio/snps,creg-gpio.txt