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The driver is intended for low to medium speed rotary encoders where hardware counter peripherals (eQEP, FTM, etc.) are unavailable or already in use. It targets the same use-cases as interrupt-cnt.c but provides full quadrature decoding instead of simple pulse counting. Features: - X1, X2, X4 quadrature decoding and pulse-direction mode - Optional index signal for zero-reset - Configurable ceiling (position clamping) - Standard counter subsystem sysfs + chrdev interface - Enable/disable via sysfs with IRQ gating Tested on TI AM64x (Cortex-A53) with a motor-driven rotary encoder at up to 2 kHz quadrature edge rate. Changes in v3: - Pick up Acked-by: Conor Dooley on the DT binding patch. - No code changes. Changes in v2: - DT binding: rephrase description to describe hardware, not driver/sysfs behaviour (Conor Dooley) - DT binding: drop redundant example without index GPIO (Conor Dooley) Wadim Mueller (3): dt-bindings: counter: add gpio-quadrature-encoder binding counter: add GPIO-based quadrature encoder driver MAINTAINERS: add entry for GPIO quadrature encoder counter driver .../counter/gpio-quadrature-encoder.yaml | 60 ++ MAINTAINERS | 7 + drivers/counter/Kconfig | 15 + drivers/counter/Makefile | 1 + drivers/counter/gpio-quadrature-encoder.c | 710 ++++++++++++++++++ 5 files changed, 793 insertions(+) create mode 100644 Documentation/devicetree/bindings/counter/gpio-quadrature-encoder.yaml create mode 100644 drivers/counter/gpio-quadrature-encoder.c -- 2.52.0