fix: Cleanups of sideband and direct kscan from review.

* Add dedicated init priority for the sideband kscan.
* Refactor sideband code for clarity.
* Tweaks to direct kscan for clarity.
* Make sideband behavior row optional for brevity.
* Allow overriding ZMK Uno sideband behaviors.

app/Kconfig

@@ -500,6 +500,15 @@ config ZMK_KSCAN_SIDEBAND_BEHAVIORS
     depends on DT_HAS_ZMK_KSCAN_SIDEBAND_BEHAVIORS_ENABLED
     select KSCAN
 
+if ZMK_KSCAN_SIDEBAND_BEHAVIORS
+
+config ZMK_KSCAN_SIDEBAND_BEHAVIORS_INIT_PRIORITY
+    int "Keyboard scan sideband behaviors driver init priority"
+    # The default kscan init priority is 90, so be sure we are lower.
+    default 95
+
+endif # ZMK_KSCAN_SIDEBAND_BEHAVIORS
+
 menu "Logging"
 
 config ZMK_LOGGING_MINIMAL

app/boards/shields/zmk_uno/zmk_uno.keymap

@@ -11,21 +11,17 @@
 #include <dt-bindings/zmk/ext_power.h>
 #include <dt-bindings/zmk/rgb.h>
 
-// Uncomment the following block if using the "Direct Wire" jumper to switch the matrix to a direct wire.
+// Uncomment the following lines if using the "Direct Wire" jumper to switch the matrix to a direct wire.
 
-/* :REMOVE ME
+// &kscan_direct { status = "okay"; };
+// &kscan_matrix { status = "disabled"; };
 
-&kscan_direct { status = "okay"; };
-&kscan_matrix { status = "disabled"; };
-
-/ {
-    chosen {
-        zmk,matrix-transform = &direct_matrix_transform;
-        zmk,kscan = &kscan_direct;
-    };
-};
-
-REMOVE ME: */
+// / {
+//     chosen {
+//         zmk,matrix-transform = &direct_matrix_transform;
+//         zmk,kscan = &kscan_direct;
+//     };
+// };
 
 / {
     keymap {

app/boards/shields/zmk_uno/zmk_uno.overlay

@@ -40,20 +40,17 @@
         compatible = "zmk,kscan-sideband-behaviors";
         kscan = <&kscan_sp3t_toggle>;
 
-        usb {
-            row = <0>;
+        first_toggle_sideband: first_toggle_sideband {
             column = <0>;
             bindings = <&out OUT_USB>;
         };
 
-        ble_zero {
-            row = <0>;
+        second_toggle_sideband: second_toggle_sideband {
             column = <1>;
             bindings = <&ble_zero>;
         };
 
-        ble_one {
-            row = <0>;
+        third_toggle_sideband: third_toggle_sideband {
             column = <2>;
             bindings = <&ble_one>;
         };

app/boards/shields/zmk_uno/zmk_uno_split.keymap

@@ -12,21 +12,18 @@
 #include <dt-bindings/zmk/outputs.h>
 #include <dt-bindings/zmk/rgb.h>
 
-// Uncomment the following block if using the "Direct Wire" jumper to switch the matrix to a direct wire.
+// Uncomment the following lines if using the "Direct Wire" jumper to switch the matrix to a direct wire.
 
-/* :REMOVE ME
 
-&kscan_direct { status = "okay"; };
-&kscan_matrix { status = "disabled"; };
+// &kscan_direct { status = "okay"; };
+// &kscan_matrix { status = "disabled"; };
 
-/ {
-    chosen {
-        zmk,matrix-transform = &split_direct_matrix_transform;
-        zmk,kscan = &kscan_direct_comp;
-    };
-};
-
-REMOVE ME: */
+// / {
+//     chosen {
+//         zmk,matrix-transform = &split_direct_matrix_transform;
+//         zmk,kscan = &kscan_direct_comp;
+//     };
+// };
 
 / {
 

app/dts/bindings/kscan/zmk,kscan-sideband-behaviors.yaml

@@ -2,8 +2,9 @@
 # SPDX-License-Identifier: MIT
 
 description: |
-  kscan sideband behavior runner. Only basic system behavior should be used,
-  since no keymap processing occurs when using them.
+  kscan sideband behavior runner. Only basic system behaviors should be used,
+  since no keymap processing occurs when using them. Primarily, that means avoiding
+  using tap-holds, sticky keys, etc. as sideband behaviors.
 
 compatible: "zmk,kscan-sideband-behaviors"
 
@@ -20,7 +21,7 @@ child-binding:
   properties:
     row:
       type: int
-      required: true
+      default: 0
     column:
       type: int
       required: true

app/module/drivers/kscan/kscan_gpio_direct.c

@@ -46,7 +46,7 @@ LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
     COND_CODE_1(DT_INST_NODE_HAS_PROP(n, input_gpios), (DT_INST_PROP_LEN(n, input_gpios)),         \
                 (DT_INST_PROP_LEN(n, input_keys)))
 
-#define KSCAN_DIRECT_INPUT_CFG_INIT(idx, inst_idx)                                                 \
+#define KSCAN_GPIO_DIRECT_INPUT_CFG_INIT(idx, inst_idx)                                            \
     KSCAN_GPIO_GET_BY_IDX(DT_DRV_INST(inst_idx), input_gpios, idx)
 #define KSCAN_KEY_DIRECT_INPUT_CFG_INIT(idx, inst_idx)                                             \
     KSCAN_GPIO_GET_BY_IDX(DT_INST_PROP_BY_IDX(inst_idx, input_keys, idx), gpios, 0)
@@ -353,7 +353,7 @@ static const struct kscan_driver_api kscan_direct_api = {
                                                                                                    \
     static struct kscan_gpio kscan_direct_inputs_##n[] = {                                         \
         COND_CODE_1(DT_INST_NODE_HAS_PROP(n, input_gpios),                                         \
-                    (LISTIFY(INST_INPUTS_LEN(n), KSCAN_DIRECT_INPUT_CFG_INIT, (, ), n)),           \
+                    (LISTIFY(INST_INPUTS_LEN(n), KSCAN_GPIO_DIRECT_INPUT_CFG_INIT, (, ), n)),      \
                     (LISTIFY(INST_INPUTS_LEN(n), KSCAN_KEY_DIRECT_INPUT_CFG_INIT, (, ), n)))};     \
                                                                                                    \
     static struct zmk_debounce_state kscan_direct_state_##n[INST_INPUTS_LEN(n)];                   \

app/src/kscan_sideband_behaviors.c

@@ -19,9 +19,9 @@
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
 struct ksbb_entry {
+    struct zmk_behavior_binding binding;
     uint8_t row;
     uint8_t column;
-    struct zmk_behavior_binding binding;
 };
 
 struct ksbb_config {
@@ -39,32 +39,53 @@ struct ksbb_data {
 
 // The kscan callback has no context with it, so we keep a static array of all possible
 // KSBBs to check when a kscan callback from the "wrapped" inner kscan fires.
-static const struct device *ksbbs[DT_NUM_INST_STATUS_OKAY(DT_DRV_COMPAT)] = {
-    DT_INST_FOREACH_STATUS_OKAY(GET_KSBB_DEV)};
+static const struct device *ksbbs[] = {DT_INST_FOREACH_STATUS_OKAY(GET_KSBB_DEV)};
 
-void ksbb_inner_kscan_callback(const struct device *dev, uint32_t row, uint32_t column,
-                               bool pressed) {
+int find_ksbb_for_inner(const struct device *inner_dev, const struct device **ksbb_dev) {
     for (int i = 0; i < ARRAY_SIZE(ksbbs); i++) {
         const struct device *ksbb = ksbbs[i];
         const struct ksbb_config *cfg = ksbb->config;
-        struct ksbb_data *data = ksbb->data;
 
-        if (cfg->kscan != dev) {
-            continue;
+        if (cfg->kscan == inner_dev) {
+            *ksbb_dev = ksbb;
+            return 0;
+        }
+    }
+
+    return -ENODEV;
+}
+
+int find_sideband_behavior(const struct device *dev, uint32_t row, uint32_t column,
+                           struct ksbb_entry **entry) {
+    const struct ksbb_config *cfg = dev->config;
+
+    for (int e = 0; e < cfg->entries_len; e++) {
+        struct ksbb_entry *candidate = &cfg->entries[e];
+
+        if (candidate->row == row && candidate->column == column) {
+            *entry = candidate;
+            return 0;
         }
+    }
 
-        for (int e = 0; e < cfg->entries_len; e++) {
-            struct ksbb_entry *entry = &cfg->entries[e];
-            if (entry->row == row && entry->column == column) {
-                struct zmk_behavior_binding_event event = {.position = INT32_MAX,
-                                                           .timestamp = k_uptime_get()};
-
-                if (pressed) {
-                    behavior_keymap_binding_pressed(&entry->binding, event);
-                } else {
-                    behavior_keymap_binding_released(&entry->binding, event);
-                }
-                return;
+    return -ENODEV;
+}
+
+void ksbb_inner_kscan_callback(const struct device *dev, uint32_t row, uint32_t column,
+                               bool pressed) {
+    struct ksbb_entry *entry = NULL;
+    const struct device *ksbb = NULL;
+
+    if (find_ksbb_for_inner(dev, &ksbb) >= 0) {
+        struct ksbb_data *data = ksbb->data;
+        if (find_sideband_behavior(ksbb, row, column, &entry) >= 0) {
+            struct zmk_behavior_binding_event event = {.position = INT32_MAX,
+                                                       .timestamp = k_uptime_get()};
+
+            if (pressed) {
+                behavior_keymap_binding_pressed(&entry->binding, event);
+            } else {
+                behavior_keymap_binding_released(&entry->binding, event);
             }
         }
 
@@ -78,10 +99,6 @@ static int ksbb_configure(const struct device *dev, kscan_callback_t callback) {
     const struct ksbb_config *cfg = dev->config;
     struct ksbb_data *data = dev->data;
 
-    if (!callback) {
-        return -EINVAL;
-    }
-
     data->callback = callback;
 
 #if IS_ENABLED(CONFIG_PM_DEVICE)
@@ -161,7 +178,7 @@ static int ksbb_pm_action(const struct device *dev, enum pm_device_action action
     struct ksbb_data ksbb_data_##n = {};                                                           \
     PM_DEVICE_DT_INST_DEFINE(n, ksbb_pm_action);                                                   \
     DEVICE_DT_INST_DEFINE(n, ksbb_init, PM_DEVICE_DT_INST_GET(n), &ksbb_data_##n,                  \
-                          &ksbb_config_##n, APPLICATION, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT,      \
-                          &ksbb_api);
+                          &ksbb_config_##n, POST_KERNEL,                                           \
+                          CONFIG_ZMK_KSCAN_SIDEBAND_BEHAVIORS_INIT_PRIORITY, &ksbb_api);
 
 DT_INST_FOREACH_STATUS_OKAY(KSBB_INST)