[gpio] Keep each interlock group in one shared flash table (#20238)

esphome/components/gpio/switch/__init__.py

@@ -36,11 +36,17 @@ async def to_code(config: ConfigType) -> None:
     pin = await cg.gpio_pin_expression(config[CONF_PIN])
     cg.add(var.set_pin(pin))
 
-    if CONF_INTERLOCK in config:
+    if (interlock := config.get(CONF_INTERLOCK)) is not None:
         cg.add_define("USE_GPIO_SWITCH_INTERLOCK")
-        interlock = []
-        for it in config[CONF_INTERLOCK]:
-            lock = await cg.get_variable(it)
-            interlock.append(lock)
-        cg.add(var.set_interlock(interlock))
+        locks = [await cg.get_variable(it) for it in interlock]
+        # The group's table lists this switch too, so every member shares one table.
+        group = sorted({str(s): s for s in (var, *locks)}.values(), key=str)
+        if len(group) > 1:
+            table = cg.shared_progmem_array(
+                "gpio_interlock",
+                switch.Switch.operator("ptr"),
+                cg.ArrayInitializer(*group),
+                constexpr=False,
+            )
+            cg.add(var.set_interlock(table, len(group)))
         cg.add(var.set_interlock_wait_time(config[CONF_INTERLOCK_WAIT_TIME]))

esphome/components/gpio/switch/gpio_switch.cpp

@@ -67,8 +67,4 @@ void GPIOSwitch::write_state(bool state) {
   this->publish_state(state);
 }
 
-#ifdef USE_GPIO_SWITCH_INTERLOCK
-void GPIOSwitch::set_interlock(const std::initializer_list<Switch *> &interlock) { this->interlock_ = interlock; }
-#endif
-
 }  // namespace esphome::gpio

esphome/components/gpio/switch/gpio_switch.h

@@ -21,7 +21,10 @@ class GPIOSwitch final : public switch_::Switch, public Component {
   void setup() override;
   void dump_config() override;
 #ifdef USE_GPIO_SWITCH_INTERLOCK
-  void set_interlock(const std::initializer_list<Switch *> &interlock);
+  /// Codegen only: the table must outlive this switch; it may list this switch, which is skipped.
+  void set_interlock(Switch *const *interlock, size_t count) {
+    this->interlock_ = ConstVector<Switch *>(interlock, count);
+  }
   void set_interlock_wait_time(uint32_t interlock_wait_time) { interlock_wait_time_ = interlock_wait_time; }
 #endif
 
@@ -30,7 +33,7 @@ class GPIOSwitch final : public switch_::Switch, public Component {
 
   GPIOPin *pin_{nullptr};
 #ifdef USE_GPIO_SWITCH_INTERLOCK
-  FixedVector<Switch *> interlock_;
+  ConstVector<Switch *> interlock_;
   uint32_t interlock_wait_time_{0};
 #endif
 };

tests/component_tests/gpio/test_gpio_switch.py

@@ -0,0 +1,33 @@
+"""Tests for the GPIO switch component."""
+
+from __future__ import annotations
+
+from collections.abc import Callable
+from pathlib import Path
+import re
+
+
+def test_gpio_switch_interlock_group_shares_one_table(
+    generate_main: Callable[[str | Path], str],
+) -> None:
+    """Every member of an interlock group points at the same flash table."""
+    main_cpp = generate_main(
+        "tests/component_tests/gpio/test_gpio_switch_interlock.yaml"
+    )
+
+    tables = re.findall(r"(gpio_interlock\w*)\[\] PROGMEM = \{([^}]*)\};", main_cpp)
+    assert tables == [("gpio_interlock", "sw_a, sw_b, sw_c")]
+    for sw in ("sw_a", "sw_b", "sw_c"):
+        assert f"{sw}->set_interlock(gpio_interlock, 3);" in main_cpp
+
+
+def test_gpio_switch_interlock_with_only_itself_has_no_table(
+    generate_main: Callable[[str | Path], str],
+) -> None:
+    """A switch interlocked only with itself gets no table and no set_interlock."""
+    main_cpp = generate_main(
+        "tests/component_tests/gpio/test_gpio_switch_interlock.yaml"
+    )
+
+    assert "sw_self->set_interlock(" not in main_cpp
+    assert "sw_self->set_interlock_wait_time(0);" in main_cpp

tests/component_tests/gpio/test_gpio_switch_interlock.yaml

@@ -0,0 +1,23 @@
+esphome:
+  name: test
+
+esp32:
+  board: esp32dev
+
+switch:
+  - platform: gpio
+    pin: 12
+    id: sw_a
+    interlock: [sw_b, sw_c]
+  - platform: gpio
+    pin: 13
+    id: sw_b
+    interlock: [sw_a, sw_c]
+  - platform: gpio
+    pin: 14
+    id: sw_c
+    interlock: [sw_a, sw_b]
+  - platform: gpio
+    pin: 15
+    id: sw_self
+    interlock: [sw_self]