feat(keymap): Add behavior binding validation, keymap APIs.

* Add ability to validate a zmk_behavior_binding against
  the behavior metadata available.
* Add keymap API for getting/setting a bindings
  in keymap layers.
* Add settings storage for keymap layer bindings.

app/Kconfig

@@ -252,6 +252,14 @@ rsource "src/split/Kconfig"
 #Basic Keyboard Setup
 endmenu
 
+menu "Keymaps"
+
+config ZMK_KEYMAP_SETTINGS_STORAGE
+    bool "Settings Save/Load"
+    depends on SETTINGS
+
+endmenu # Keymaps
+
 rsource "src/studio/Kconfig"
 
 menu "Display/LED Options"

app/include/zmk/behavior.h

@@ -12,7 +12,7 @@
 #define ZMK_BEHAVIOR_TRANSPARENT 1
 
 struct zmk_behavior_binding {
-    char *behavior_dev;
+    const char *behavior_dev;
     uint32_t param1;
     uint32_t param2;
 };
@@ -58,3 +58,16 @@ zmk_behavior_local_id_t zmk_behavior_get_local_id(const char *name);
  * @retval NULL if the behavior is not found or its initialization function failed.
  */
 const char *zmk_behavior_find_behavior_name_from_local_id(zmk_behavior_local_id_t local_id);
+
+
+/**
+ * @brief Validate a given behavior binding matches the behavior metadata describing valid parameters.
+ *
+ * @param binding The behavior binding to validate
+ *
+ * @retval 0 if the passed in binding is valid.
+ * @retval -ENODEV if binding is NULL.
+ * @retval -EINVAL if binding parameters are not valid for the behavior metadata.
+ */
+int zmk_behavior_validate_binding(const struct zmk_behavior_binding *binding);
+

app/include/zmk/keymap.h

@@ -24,6 +24,14 @@ int zmk_keymap_layer_toggle(uint8_t layer);
 int zmk_keymap_layer_to(uint8_t layer);
 const char *zmk_keymap_layer_name(uint8_t layer);
 
+const struct zmk_behavior_binding *zmk_keymap_get_layer_binding_at_idx(uint8_t layer,
+                                                                       uint8_t binding_idx);
+int zmk_keymap_set_layer_binding_at_idx(uint8_t layer, uint8_t binding_idx,
+                                        const struct zmk_behavior_binding binding);
+
+int zmk_keymap_save_changes(void);
+int zmk_keymap_discard_changes(void);
+
 int zmk_keymap_position_state_changed(uint8_t source, uint32_t position, bool pressed,
                                       int64_t timestamp);
 

app/src/behavior.c

@@ -19,6 +19,8 @@
 
 #include <drivers/behavior.h>
 #include <zmk/behavior.h>
+#include <zmk/hid.h>
+#include <zmk/matrix.h>
 
 #include <zephyr/logging/log.h>
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
@@ -118,12 +120,11 @@ static int behavior_handle_set(const char *name, size_t len, settings_read_cb re
                 return 0;
             }
         }
-
         return -EINVAL;
     }
 
     return 0;
-};
+}
 
 static int behavior_handle_commit(void) {
     LOG_DBG("COMMIT!");
@@ -139,18 +140,13 @@ static int behavior_handle_commit(void) {
         char setting_name[32];
         sprintf(setting_name, "behavior/local_id/%d", item->local_id);
         settings_save_one(setting_name, item->device->name, strlen(item->device->name));
-    }
-
-    return 0;
 }
 
 SETTINGS_STATIC_HANDLER_DEFINE(behavior, "behavior", NULL, behavior_handle_set,
                                behavior_handle_commit, NULL);
 
 static int behavior_local_id_init(void) {
-    // LOAD SETTINGS!
     settings_load_subtree("behavior");
-    // TODO: Populate the local IDs from the settings table
 
     return 0;
 }
@@ -165,6 +161,135 @@ SYS_INIT(behavior_local_id_init, APPLICATION, CONFIG_APPLICATION_INIT_PRIORITY);
 
 #endif
 
+#if IS_ENABLED(CONFIG_ZMK_BEHAVIOR_METADATA)
+static int validate_hid_usage(uint16_t usage_page, uint16_t usage_id) {
+    LOG_DBG("Validate usage %d in page %d", usage_id, usage_page);
+    switch (usage_page) {
+    case HID_USAGE_KEY:
+        if (usage_id == 0 || usage_id > ZMK_HID_KEYBOARD_NKRO_MAX_USAGE) {
+            return -EINVAL;
+        }
+        break;
+    case HID_USAGE_CONSUMER:
+        if (usage_id >
+            COND_CODE_1(IS_ENABLED(CONFIG_ZMK_HID_CONSUMER_REPORT_USAGES_BASIC), (0xFF), (0xFFF))) {
+            return -EINVAL;
+        }
+        break;
+    default:
+        LOG_WRN("Unsupported HID usage page %d", usage_page);
+        return -EINVAL;
+    }
+
+    return 0;
+}
+
+static int validate_standard_param(enum behavior_parameter_standard_domain standard_domain,
+                                   uint32_t val) {
+    switch (standard_domain) {
+    case BEHAVIOR_PARAMETER_STANDARD_DOMAIN_NULL:
+        if (val != 0) {
+            return -EINVAL;
+        }
+        break;
+    case BEHAVIOR_PARAMETER_STANDARD_DOMAIN_HID_USAGE:
+        return validate_hid_usage(ZMK_HID_USAGE_PAGE(val), ZMK_HID_USAGE_ID(val));
+    case BEHAVIOR_PARAMETER_STANDARD_DOMAIN_LAYER_INDEX:
+        if (val >= ZMK_KEYMAP_LEN) {
+            return -EINVAL;
+        }
+        break;
+    case BEHAVIOR_PARAMETER_STANDARD_DOMAIN_HSV:
+        // TODO: No real way to validate? Maybe max brightness?
+        break;
+    }
+
+    return 0;
+}
+
+static int validate_custom_params(const struct behavior_parameter_metadata_custom *custom,
+                                  uint32_t param1, uint32_t param2) {
+    if (!custom) {
+        return -ENODEV;
+    }
+
+    for (int s = 0; s < custom->sets_len; s++) {
+        const struct behavior_parameter_metadata_custom_set *set = &custom->sets[s];
+
+        bool had_param1_metadata = false, had_param2_metadata = false;
+        bool param1_matched = false, param2_matched = false;
+
+        for (int v = 0; v < set->values_len && (!param1_matched || !param2_matched); v++) {
+            const struct behavior_parameter_value_metadata *value_meta = &set->values[v];
+            uint32_t param = value_meta->position == 0 ? param1 : param2;
+            bool *matched = value_meta->position == 0 ? &param1_matched : &param2_matched;
+
+            *(value_meta->position == 0 ? &had_param1_metadata : &had_param2_metadata) = true;
+
+            switch (value_meta->type) {
+            case BEHAVIOR_PARAMETER_VALUE_METADATA_TYPE_STANDARD:
+                if (validate_standard_param(value_meta->standard, param) == 0) {
+                    *matched = true;
+                }
+                break;
+            case BEHAVIOR_PARAMETER_VALUE_METADATA_TYPE_VALUE:
+                if (param == value_meta->value) {
+                    *matched = true;
+                }
+                break;
+            case BEHAVIOR_PARAMETER_VALUE_METADATA_TYPE_RANGE:
+                if (param >= value_meta->range.min && param <= value_meta->range.max) {
+                    *matched = true;
+                }
+                break;
+            }
+        }
+
+        if ((param1_matched || (!had_param1_metadata && param1 == 0)) &&
+            (param2_matched || (!had_param2_metadata && param2 == 0))) {
+            return 0;
+        }
+    }
+
+    return -EINVAL;
+}
+
+#endif // IS_ENABLED(CONFIG_ZMK_BEHAVIOR_METADATA)
+
+int zmk_behavior_validate_binding(const struct zmk_behavior_binding *binding) {
+#if IS_ENABLED(CONFIG_ZMK_BEHAVIOR_METADATA)
+    const struct device *behavior = zmk_behavior_get_binding(binding->behavior_dev);
+
+    if (!behavior) {
+        return -ENODEV;
+    }
+
+    struct behavior_parameter_metadata metadata;
+    int ret = behavior_get_parameter_domains(behavior, &metadata);
+
+    if (ret < 0) {
+        return ret;
+    }
+
+    switch (metadata.type) {
+    case BEHAVIOR_PARAMETER_METADATA_STANDARD:
+        int ret = validate_standard_param(metadata.standard.param1, binding->param1);
+
+        if (ret < 0) {
+            return ret;
+        }
+
+        return validate_standard_param(metadata.standard.param2, binding->param2);
+    case BEHAVIOR_PARAMETER_METADATA_CUSTOM:
+        return validate_custom_params(metadata.custom, binding->param1, binding->param2);
+    default:
+        return -ENOTSUP;
+    }
+#else
+    return 0;
+#endif // IS_ENABLED(CONFIG_ZMK_BEHAVIOR_METADATA)
+}
+
 #if IS_ENABLED(CONFIG_LOG)
 static int check_behavior_names(void) {
     // Behavior names must be unique, but we don't have a good way to enforce this