Recalibrate the touchwheel after unlocking

Also power it down whilst we're locked. This saves about half a
milliamp.

src/drivers/include/drivers/touchwheel.hpp

@@ -39,7 +39,8 @@ class TouchWheel {
   auto Update() -> void;
   auto GetTouchWheelData() const -> TouchWheelData;
 
-  auto PowerDown() -> void;
+  auto Recalibrate() -> void;
+  auto LowPowerMode(bool en) -> void;
 
  private:
   TouchWheelData data_;

src/drivers/touchwheel.cpp

@@ -137,8 +137,12 @@ TouchWheelData TouchWheel::GetTouchWheelData() const {
   return data_;
 }
 
-auto TouchWheel::PowerDown() -> void {
-  WriteRegister(LOW_POWER, 0);
+auto TouchWheel::Recalibrate() -> void {
+  WriteRegister(CALIBRATE, 1);
+}
+
+auto TouchWheel::LowPowerMode(bool en) -> void {
+  WriteRegister(LOW_POWER, en ? 0 : 1);
 }
 
 }  // namespace drivers

src/tangara/input/input_device.hpp

@@ -32,6 +32,11 @@ class IInputDevice {
   virtual auto triggers() -> std::vector<std::reference_wrapper<TriggerHooks>> {
     return {};
   }
+
+  /* Called by the LVGL driver when controls are being locked. */
+  virtual auto onLock() -> void {}
+  /* Called by the LVGL driver when controls are being unlocked. */
+  virtual auto onUnlock() -> void {}
 };
 
 }  // namespace input

src/tangara/input/input_touch_wheel.cpp

@@ -108,6 +108,15 @@ auto TouchWheel::triggers()
   return {centre_, up_, right_, down_, left_};
 }
 
+auto TouchWheel::onLock() -> void {
+  wheel_.LowPowerMode(true);
+}
+
+auto TouchWheel::onUnlock() -> void {
+  wheel_.LowPowerMode(false);
+  wheel_.Recalibrate();
+}
+
 auto TouchWheel::sensitivity() -> lua::Property& {
   return sensitivity_;
 }

src/tangara/input/input_touch_wheel.hpp

@@ -12,12 +12,12 @@
 #include "indev/lv_indev.h"
 
 #include "drivers/haptics.hpp"
+#include "drivers/nvs.hpp"
+#include "drivers/touchwheel.hpp"
 #include "input/input_device.hpp"
 #include "input/input_hook.hpp"
 #include "input/input_trigger.hpp"
 #include "lua/property.hpp"
-#include "drivers/nvs.hpp"
-#include "drivers/touchwheel.hpp"
 
 namespace input {
 
@@ -30,6 +30,9 @@ class TouchWheel : public IInputDevice {
   auto name() -> std::string override;
   auto triggers() -> std::vector<std::reference_wrapper<TriggerHooks>> override;
 
+  auto onLock() -> void override;
+  auto onUnlock() -> void override;
+
   auto sensitivity() -> lua::Property&;
 
  private:

src/tangara/input/lvgl_input_driver.cpp

@@ -132,6 +132,17 @@ auto LvglInputDriver::feedback(uint8_t event) -> void {
   }
 }
 
+auto LvglInputDriver::lock(bool l) -> void {
+  is_locked_ = l;
+  for (auto&& device : inputs_) {
+    if (l) {
+      device->onLock();
+    } else {
+      device->onUnlock();
+    }
+  }
+}
+
 LvglInputDriver::LuaTrigger::LuaTrigger(LvglInputDriver& driver,
                                         IInputDevice& dev,
                                         TriggerHooks& trigger)

src/tangara/input/lvgl_input_driver.hpp

@@ -40,8 +40,7 @@ class LvglInputDriver {
   auto setGroup(lv_group_t*) -> void;
   auto read(lv_indev_data_t* data) -> void;
   auto feedback(uint8_t) -> void;
-
-  auto lock(bool l) -> void { is_locked_ = l; }
+  auto lock(bool l) -> void;
 
   auto pushHooks(lua_State* L) -> int;
 

src/tangara/system_fsm/idle.cpp

@@ -76,7 +76,7 @@ void Idle::react(const internal::IdleTimeout& ev) {
   // other state machines, etc.
   auto touchwheel = sServices->touchwheel();
   if (touchwheel) {
-    touchwheel.value()->PowerDown();
+    touchwheel.value()->LowPowerMode(true);
   }
 
   auto& gpios = sServices->gpios();