From: Hans Verkuil <hans.verkuil@xxxxxxxxx> This driver adds support for CEC implementations that use a pull-up GPIO pin. While SoCs exist that do this, the primary use-case is to turn a single-board computer into a cheap CEC debugger. Together with 'cec-ctl --monitor-pin' you can do low-level CEC bus monitoring and do protocol analysis. And error injection is also planned for the future. Here is an example using the Raspberry Pi 3: https://hverkuil.home.xs4all.nl/rpi3-cec.jpg A patch for the Raspberry Pi 2B/3 is added below for reference. It uses pin 7 aka BCM4 aka GPCLK0 on the GPIO pin header. While this example is for the Rpi, this driver will work for any SoC with a pull-up GPIO pin. I have one question: is there a generic way to check/force the gpio to pull-up mode? I have not found that, but I am no gpio-expert. Regards, Hans --- cut here --- diff --git a/arch/arm/boot/dts/bcm2836-rpi-2-b.dts b/arch/arm/boot/dts/bcm2836-rpi-2-b.dts index bf19e8cfb9e6..8cb82a70f33d 100644 --- a/arch/arm/boot/dts/bcm2836-rpi-2-b.dts +++ b/arch/arm/boot/dts/bcm2836-rpi-2-b.dts @@ -24,6 +24,11 @@ linux,default-trigger = "default-on"; }; }; + + cec-gpio { + compatible = "cec-gpio"; + gpio = <&gpio 4 GPIO_ACTIVE_HIGH>; + }; }; &gpio { diff --git a/arch/arm64/boot/dts/broadcom/bcm2837-rpi-3-b.dts b/arch/arm64/boot/dts/broadcom/bcm2837-rpi-3-b.dts index 972f14db28ac..cd0ec70732f4 100644 --- a/arch/arm64/boot/dts/broadcom/bcm2837-rpi-3-b.dts +++ b/arch/arm64/boot/dts/broadcom/bcm2837-rpi-3-b.dts @@ -17,6 +17,11 @@ gpios = <&gpio 47 0>; }; }; + + cec-gpio { + compatible = "cec-gpio"; + gpio = <&gpio 4 GPIO_ACTIVE_HIGH>; + }; }; &uart1 { --- cut here --- Hans Verkuil (3): dt-bindings: document the CEC GPIO bindings cec-gpio: add HDMI CEC GPIO driver MAINTAINERS: add cec-gpio entry .../devicetree/bindings/media/cec-gpio.txt | 18 ++ MAINTAINERS | 9 + drivers/media/platform/Kconfig | 10 ++ drivers/media/platform/Makefile | 2 + drivers/media/platform/cec-gpio/Makefile | 1 + drivers/media/platform/cec-gpio/cec-gpio.c | 190 +++++++++++++++++++++ 6 files changed, 230 insertions(+) create mode 100644 Documentation/devicetree/bindings/media/cec-gpio.txt create mode 100644 drivers/media/platform/cec-gpio/Makefile create mode 100644 drivers/media/platform/cec-gpio/cec-gpio.c -- 2.13.2
