Trackball rewrite (#600)

- Implement generic trackball settings
- Refactor T-Deck trackball driver into generic driver at `Drivers/gpio-trackball-module`
- Automatically bind/unbind trackball devices with LVGL
- Automatically load settings for trackball devices on boot

TactilityKernel/include/tactility/drivers/trackball.h

@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: Apache-2.0
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include <tactility/device.h>
+#include <tactility/error.h>
+
+/**
+ * @brief API for trackball drivers.
+ * Reports raw, unscaled movement: sensitivity and mode (encoder vs. pointer) are UI concerns
+ * layered on top by the consumer (see lvgl/devices/trackball.h), not something this driver knows about.
+ */
+struct TrackballApi {
+    /**
+     * @brief Reads the accumulated movement since the last read, then resets it to zero.
+     * @param[in] device the trackball device
+     * @param[out] out_dx horizontal movement (right positive), in raw pulses
+     * @param[out] out_dy vertical movement (down positive), in raw pulses
+     * @retval ERROR_NONE when the operation was successful
+     */
+    error_t (*read_delta)(struct Device* device, int32_t* out_dx, int32_t* out_dy);
+
+    /**
+     * @brief Gets whether the click button is currently pressed.
+     * @param[in] device the trackball device
+     * @param[out] out_pressed true when pressed
+     * @retval ERROR_NONE when the operation was successful
+     */
+    error_t (*get_button_pressed)(struct Device* device, bool* out_pressed);
+};
+
+/**
+ * @brief Reads the accumulated movement using the specified trackball device.
+ */
+error_t trackball_read_delta(struct Device* device, int32_t* out_dx, int32_t* out_dy);
+
+/**
+ * @brief Gets whether the click button is currently pressed on the specified trackball device.
+ */
+error_t trackball_get_button_pressed(struct Device* device, bool* out_pressed);
+
+extern const struct DeviceType TRACKBALL_TYPE;
+
+#ifdef __cplusplus
+}
+#endif

TactilityKernel/source/drivers/trackball.cpp

@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: Apache-2.0
+#include <tactility/device.h>
+#include <tactility/drivers/trackball.h>
+#include <tactility/error.h>
+
+#define TRACKBALL_DRIVER_API(driver) ((struct TrackballApi*)driver->api)
+
+extern "C" {
+
+error_t trackball_read_delta(Device* device, int32_t* out_dx, int32_t* out_dy) {
+    const auto* driver = device_get_driver(device);
+    return TRACKBALL_DRIVER_API(driver)->read_delta(device, out_dx, out_dy);
+}
+
+error_t trackball_get_button_pressed(Device* device, bool* out_pressed) {
+    const auto* driver = device_get_driver(device);
+    return TRACKBALL_DRIVER_API(driver)->get_button_pressed(device, out_pressed);
+}
+
+const DeviceType TRACKBALL_TYPE {
+    .name = "trackball"
+};
+
+}

TactilityKernel/source/symbols.c

@@ -29,6 +29,7 @@
 #include <tactility/drivers/rtc.h>
 #include <tactility/drivers/sdcard.h>
 #include <tactility/drivers/spi_controller.h>
+#include <tactility/drivers/trackball.h>
 #include <tactility/drivers/uart_controller.h>
 #include <tactility/drivers/usb_host_hid.h>
 #include <tactility/drivers/usb_host_midi.h>
@@ -294,6 +295,10 @@ const struct ModuleSymbol KERNEL_SYMBOLS[] = {
     DEFINE_MODULE_SYMBOL(spi_controller_try_lock),
     DEFINE_MODULE_SYMBOL(spi_controller_unlock),
     DEFINE_MODULE_SYMBOL(SPI_CONTROLLER_TYPE),
+    // drivers/trackball
+    DEFINE_MODULE_SYMBOL(trackball_read_delta),
+    DEFINE_MODULE_SYMBOL(trackball_get_button_pressed),
+    DEFINE_MODULE_SYMBOL(TRACKBALL_TYPE),
     // drivers/uart_controller
     DEFINE_MODULE_SYMBOL(uart_controller_open),
     DEFINE_MODULE_SYMBOL(uart_controller_close),