Hi All, I have a hardware design where a single SPI chip select is steered by a GPIO being asserted or de-asserted. On older kernels I was able to (ab)use a gpio-hog and cs-gpios to deal with this. Unfortunately recent changes have stopped my hacks from working. I've tried adapting cs-gpios to work with my particular hardware but I came to the realisation that the current cs-gpios support assumes a 1:1 mapping of gpio to SPI device whereas my hardware used the state of the gpio selecting the device i.e. a 1:2 mapping. This is my attempt to implement a driver to deal with this. One nice property is that it is pretty much self contained. The only change to the core SPI infrastructure is exposing a function I needed to lookup the spi_controller instance. Chris Packham (3): dt-bindings: spi: Add spi-mux-gpio spi: Make of_find_spi_controller_by_node visible spi: Add SPI bus gpio multiplexer .../devicetree/bindings/spi/spi-mux-gpio.txt | 46 +++++ drivers/spi/Kconfig | 7 + drivers/spi/Makefile | 1 + drivers/spi/spi-mux-gpio.c | 169 ++++++++++++++++++ drivers/spi/spi.c | 7 +- include/linux/spi/spi.h | 7 + 6 files changed, 234 insertions(+), 3 deletions(-) create mode 100644 Documentation/devicetree/bindings/spi/spi-mux-gpio.txt create mode 100644 drivers/spi/spi-mux-gpio.c -- 2.21.0
