Remove interrupt config/rely on pin set

If the interrupt pin is set, use the interrupt code, else poll.

This change results in a slightly larger executable in both cases,
with unreachable code. More so in the case of polling, bet the
difference is not great.

app/module/drivers/kscan/CMakeLists.txt

@@ -1,4 +1,4 @@
-# Copyright (c) 2020 The ZMK Contributors
+# Copyright (c) 2020-2023 The ZMK Contributors
 # SPDX-License-Identifier: MIT
 
 zephyr_library_amend()

app/module/drivers/kscan/Kconfig

@@ -66,7 +66,7 @@ endif # ZMK_KSCAN_GPIO_MATRIX
 
 if ZMK_KSCAN_GPIO_CHARLIPLEX
 
-config ZMK_KSCAN_MATRIX_WAIT_BEFORE_INPUTS
+config ZMK_KSCAN_CHARLIPLEX_WAIT_BEFORE_INPUTS
     int "Ticks to wait before reading inputs after an output set active"
     default 0
     help
@@ -97,9 +97,6 @@ if ZMK_KSCAN_GPIO_DRIVER
 config ZMK_KSCAN_MATRIX_POLLING
     bool "Poll for key event triggers instead of using interrupts on matrix boards."
 
-config ZMK_KSCAN_CHARLIPLEX_POLLING
-    bool "Poll for key event triggers instead of using interrupts on multiplex boards."
-
 config ZMK_KSCAN_DIRECT_POLLING
     bool "Poll for key event triggers instead of using interrupts on direct wired boards."
 

app/module/dts/bindings/kscan/zmk,kscan-gpio-charliplex.yaml

@@ -1,4 +1,4 @@
-# Copyright (c) 2022 The ZMK Contributors
+# Copyright (c) 2023 The ZMK Contributors
 # SPDX-License-Identifier: MIT
 
 description: GPIO keyboard charliplex matrix controller
@@ -13,7 +13,6 @@ properties:
     required: true
   interrupt-gpios:
     type: phandle-array
-    required: true
   debounce-press-ms:
     type: int
     default: 5

docs/docs/config/kscan.md

@@ -151,13 +151,15 @@ The output pins (e.g. columns for `col2row`) should have the flag `GPIO_ACTIVE_H
 
 ## Charliplex Driver
 
-Keyboard scan driver where keys are arranged on a matrix with each GPIO used as both input and output. This driver enables n pins to drive up to n\*(n-1) keys.
+Keyboard scan driver where keys are arranged on a matrix with each GPIO used as both input and output.
+
+- With `interrupt-gpios` unset, this allows n pins to drive n\*(n-1) keys.
+- With `interrupt-gpios` set, n pins will drive (n-1)\*(n-2) keys, but provide much improved power handling.
 
 Definition file: [zmk/app/drivers/kscan/Kconfig](https://github.com/zmkfirmware/zmk/blob/main/app/drivers/kscan/Kconfig)
 
 | Config                                              | Type        | Description                                                               | Default |
 | --------------------------------------------------- | ----------- | ------------------------------------------------------------------------- | ------- |
-| `CONFIG_ZMK_KSCAN_CHARLIPLEX_POLLING`              | bool        | Poll for key presses instead of using interrupts                          | n       |
 | `CONFIG_ZMK_KSCAN_CHARLIPLEX_WAIT_BEFORE_INPUTS`   | int (ticks) | How long to wait before reading input pins after setting output active    | 0       |
 | `CONFIG_ZMK_KSCAN_CHARLIPLEX_WAIT_BETWEEN_OUTPUTS` | int (ticks) | How long to wait between each output to allow previous output to "settle" | 0       |
 
@@ -171,14 +173,14 @@ Applies to: `compatible = "zmk,kscan-gpio-charliplex"`
 Definition file: [zmk/app/drivers/zephyr/dts/bindings/kscan/zmk,kscan-gpio-charliplex.yaml](https://github.com/zmkfirmware/zmk/blob/main/app/drivers/zephyr/dts/bindings/kscan/zmk%2Ckscan-gpio-charliplex.yaml)
 
 | Property                  | Type       | Description                                                                                 | Default |
-| ------------------------- | ---------- | ----------------------------------------------------------------------------------------------------------- | ------- |
+| ------------------------- | ---------- | ------------------------------------------------------------------------------------------- | ------- |
-| `label`                   | string     | Unique label for the node                                                                                   |         |
+| `label`                   | string     | Unique label for the node.                                                                  |         |
-| `gpios`                   | GPIO array | GPIOs used, listed in order                                                                                 |         |
+| `gpios`                   | GPIO array | GPIOs used, listed in order.                                                                |         |
-| `interrupt-gpios`         | GPIO array | A single GPIO to use for interrupt                                                                          |         |
+| `interrupt-gpios`         | GPIO array | A single GPIO to use for interrupt. Leaving this empty will enable continuous polling.      |         |
 | `debounce-press-ms`       | int        | Debounce time for key press in milliseconds. Use 0 for eager debouncing.                    | 5       |
 | `debounce-release-ms`     | int        | Debounce time for key release in milliseconds.                                              | 5       |
 | `debounce-scan-period-ms` | int        | Time between reads in milliseconds when any key is pressed.                                 | 1       |
-| `poll-period-ms`          | int        | Time between reads in milliseconds when no key is pressed and `CONFIG_ZMK_KSCAN_MATRIX_POLLING` is enabled. | 10      |
+| `poll-period-ms`          | int        | Time between reads in milliseconds when no key is pressed and `interrupt-gpois` is not set. | 10      |
 
 Define the transform with a [matrix transform](#matrix-transform). The row is always the driven pin, and the column always the receiving pin (input to the controller).
 For example, in `RC(5,0)` power flows from the 6th pin in `gpios` to the 1st pin in `gpios`.