feat: Add input split support.

app/CMakeLists.txt

@@ -42,9 +42,9 @@ target_sources_ifdef(CONFIG_USB_DEVICE_STACK app PRIVATE src/events/usb_conn_sta
 target_sources(app PRIVATE src/behaviors/behavior_reset.c)
 target_sources_ifdef(CONFIG_ZMK_EXT_POWER app PRIVATE src/behaviors/behavior_ext_power.c)
 target_sources_ifdef(CONFIG_ZMK_BEHAVIOR_SOFT_OFF app PRIVATE src/behaviors/behavior_soft_off.c)
+add_subdirectory_ifdef(CONFIG_ZMK_MOUSE src/mouse/)
 if ((NOT CONFIG_ZMK_SPLIT) OR CONFIG_ZMK_SPLIT_ROLE_CENTRAL)
   target_sources(app PRIVATE src/hid.c)
-  add_subdirectory_ifdef(CONFIG_ZMK_MOUSE src/mouse/)
   target_sources(app PRIVATE src/behaviors/behavior_key_press.c)
   target_sources_ifdef(CONFIG_ZMK_BEHAVIOR_KEY_TOGGLE app PRIVATE src/behaviors/behavior_key_toggle.c)
   target_sources_ifdef(CONFIG_ZMK_BEHAVIOR_HOLD_TAP app PRIVATE src/behaviors/behavior_hold_tap.c)

app/dts/bindings/zmk,input-split.yaml

@@ -0,0 +1,15 @@
+include: [base.yaml]
+
+compatible: "zmk,input-split"
+
+description: Device to wire up an input device for split use.
+
+properties:
+  reg:
+    required: true
+
+  device:
+    type: phandle
+
+  input-processors:
+    type: phandle-array

app/include/zmk/mouse/input_split.h

@@ -0,0 +1,10 @@
+/*
+ * Copyright (c) 2024 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+int zmk_input_split_report_peripheral_event(uint8_t reg, uint8_t type, uint16_t code, int32_t value,
+                                            bool sync);

app/include/zmk/split/bluetooth/service.h

@@ -31,8 +31,17 @@ struct zmk_split_run_behavior_payload {
     char behavior_dev[ZMK_SPLIT_RUN_BEHAVIOR_DEV_LEN];
 } __packed;
 
+struct zmk_split_input_event_payload {
+    uint8_t type;
+    uint16_t code;
+    uint32_t value;
+    uint8_t sync;
+} __packed;
+
 int zmk_split_bt_position_pressed(uint8_t position);
 int zmk_split_bt_position_released(uint8_t position);
 int zmk_split_bt_sensor_triggered(uint8_t sensor_index,
                                   const struct zmk_sensor_channel_data channel_data[],
                                   size_t channel_data_size);
+
+int zmk_split_bt_report_input(uint8_t reg, uint8_t type, uint16_t code, int32_t value, bool sync);

app/include/zmk/split/bluetooth/uuid.h

@@ -19,3 +19,4 @@
 #define ZMK_SPLIT_BT_CHAR_SENSOR_STATE_UUID ZMK_BT_SPLIT_UUID(0x00000003)
 #define ZMK_SPLIT_BT_UPDATE_HID_INDICATORS_UUID ZMK_BT_SPLIT_UUID(0x00000004)
 #define ZMK_SPLIT_BT_SELECT_PHYS_LAYOUT_UUID ZMK_BT_SPLIT_UUID(0x00000005)
+#define ZMK_SPLIT_BT_INPUT_EVENT_UUID ZMK_BT_SPLIT_UUID(0x00000006)

app/src/mouse/CMakeLists.txt

@@ -1,9 +1,10 @@
 # Copyright (c) 2024 The ZMK Contributors
 # SPDX-License-Identifier: MIT
 
-target_sources(app PRIVATE input_listener.c)
+target_sources_ifdef(CONFIG_ZMK_INPUT_LISTENER app PRIVATE input_listener.c)
 target_sources_ifdef(CONFIG_ZMK_INPUT_PROCESSOR_TRANSFORM app PRIVATE input_processor_transform.c)
 target_sources_ifdef(CONFIG_ZMK_INPUT_PROCESSOR_SCALER app PRIVATE input_processor_scaler.c)
 target_sources_ifdef(CONFIG_ZMK_INPUT_PROCESSOR_TEMP_LAYER app PRIVATE input_processor_temp_layer.c)
 target_sources_ifdef(CONFIG_ZMK_INPUT_PROCESSOR_CODE_MAPPER app PRIVATE input_processor_code_mapper.c)
-target_sources_ifdef(CONFIG_ZMK_MOUSE_SMOOTH_SCROLLING app PRIVATE resolution_multipliers.c)
+target_sources_ifdef(CONFIG_ZMK_MOUSE_SMOOTH_SCROLLING app PRIVATE resolution_multipliers.c)
+target_sources_ifdef(CONFIG_ZMK_INPUT_SPLIT app PRIVATE input_split.c)

app/src/mouse/Kconfig

@@ -12,11 +12,29 @@ if ZMK_MOUSE
 config INPUT_GPIO_KEYS
     default n
 
+config INPUT_THREAD_STACK_SIZE
+    default 1024 if ZMK_SPLIT && !ZMK_SPLIT_ROLE_CENTRAL
+
+if !ZMK_SPLIT || ZMK_SPLIT_ROLE_CENTRAL
+
 config ZMK_MOUSE_SMOOTH_SCROLLING
     bool "Smooth Scrolling"
     help
       Enable smooth scrolling, with hosts that support HID Resolution Multipliers
 
+config ZMK_INPUT_LISTENER
+    bool "Input listener for processing input events in the system"
+    default y
+    depends on DT_HAS_ZMK_INPUT_LISTENER_ENABLED
+
+
+config ZMK_INPUT_PROCESSOR_TEMP_LAYER
+    bool "Temporary Layer Input Processor"
+    default y
+    depends on DT_HAS_ZMK_INPUT_PROCESSOR_TEMP_LAYER_ENABLED
+
+endif
+
 config ZMK_INPUT_PROCESSOR_TRANSFORM
     bool "Transform Input Processor"
     default y
@@ -27,15 +45,22 @@ config ZMK_INPUT_PROCESSOR_SCALER
     default y
     depends on DT_HAS_ZMK_INPUT_PROCESSOR_SCALER_ENABLED
 
-config ZMK_INPUT_PROCESSOR_TEMP_LAYER
-    bool "Temporary Layer Input Processor"
-    default y
-    depends on DT_HAS_ZMK_INPUT_PROCESSOR_TEMP_LAYER_ENABLED
-
 config ZMK_INPUT_PROCESSOR_CODE_MAPPER
     bool "Code Mapper Input Processor"
     default y
     depends on DT_HAS_ZMK_INPUT_PROCESSOR_CODE_MAPPER_ENABLED
 
+config ZMK_INPUT_SPLIT
+    bool "Split input support"
+    default y
+    depends on DT_HAS_ZMK_INPUT_SPLIT_ENABLED && ZMK_SPLIT
+
+if ZMK_INPUT_SPLIT
+
+config ZMK_INPUT_SPLIT_INIT_PRIORITY
+    int "Input Split initialization priority"
+    default INPUT_INIT_PRIORITY
+
+endif # ZMK_INPUT_SPLIT
 
 endif

app/src/mouse/input_split.c

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2024 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#define DT_DRV_COMPAT zmk_input_split
+
+#include <zephyr/kernel.h>
+#include <zephyr/device.h>
+#include <zephyr/input/input.h>
+#include <drivers/input_processor.h>
+
+#include <zephyr/logging/log.h>
+
+LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
+
+#if IS_ENABLED(CONFIG_ZMK_SPLIT_ROLE_CENTRAL)
+
+struct zis_entry {
+    uint8_t reg;
+    const struct device *dev;
+};
+
+#define ZIS_ENTRY(n) {.reg = DT_INST_REG_ADDR(n), .dev = DEVICE_DT_GET(DT_DRV_INST(n))},
+
+static const struct zis_entry proxy_inputs[] = {DT_INST_FOREACH_STATUS_OKAY(ZIS_ENTRY)};
+
+int zmk_input_split_report_peripheral_event(uint8_t reg, uint8_t type, uint16_t code, int32_t value,
+                                            bool sync) {
+    LOG_DBG("Got peripheral event for %d!", reg);
+    for (size_t i = 0; i < ARRAY_SIZE(proxy_inputs); i++) {
+        if (reg == proxy_inputs[i].reg) {
+            return input_report(proxy_inputs[i].dev, type, code, value, sync, K_NO_WAIT);
+        }
+    }
+
+    return -ENODEV;
+}
+
+#define ZIS_INST(n)                                                                                \
+    DEVICE_DT_INST_DEFINE(n, NULL, NULL, NULL, NULL, POST_KERNEL,                                  \
+                          CONFIG_ZMK_INPUT_SPLIT_INIT_PRIORITY, NULL);
+
+#else
+
+#include <zmk/split/bluetooth/service.h>
+
+#define ZIS_INST(n)                                                                                \
+    static const struct zmk_input_processor_entry processors_##n[] =                               \
+        COND_CODE_1(DT_INST_NODE_HAS_PROP(n, input_processors),                                    \
+                    ({LISTIFY(DT_INST_PROP_LEN(n, input_processors),                               \
+                              ZMK_INPUT_PROCESSOR_ENTRY_AT_IDX, (, ), DT_DRV_INST(n))}),           \
+                    ({}));                                                                         \
+    BUILD_ASSERT(DT_INST_NODE_HAS_PROP(n, device),                                                 \
+                 "Peripheral input splits need an `input` property set");                          \
+    void split_input_handler_##n(struct input_event *evt) {                                        \
+        for (size_t i = 0; i < ARRAY_SIZE(processors_##n); i++) {                                  \
+            zmk_input_processor_handle_event(processors_##n[i].dev, evt, processors_##n[i].param1, \
+                                             processors_##n[i].param2, NULL);                      \
+        }                                                                                          \
+        zmk_split_bt_report_input(DT_INST_REG_ADDR(n), evt->type, evt->code, evt->value,           \
+                                  evt->sync);                                                      \
+    }                                                                                              \
+    INPUT_CALLBACK_DEFINE(DEVICE_DT_GET(DT_INST_PHANDLE(n, device)), split_input_handler_##n);
+
+#endif
+
+DT_INST_FOREACH_STATUS_OKAY(ZIS_INST)