LoRa device type + SX1262 kernel driver (first checkpoint) (#565)

Adds sub-GHz radio support to Tactility as a first-class kernel device type, plus a
driver for the Semtech SX1262. Continues the radio work discussed in #342, brought up to
the current kernel driver model (rather than the deprecated tt::hal layer the earlier
prototype targeted).

Drivers/sx126x-module/include/bindings/sx1262.h

@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: Apache-2.0
+#pragma once
+
+#include <tactility/bindings/bindings.h>
+#include <drivers/sx1262.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+DEFINE_DEVICETREE(sx1262, struct Sx1262Config)
+
+#ifdef __cplusplus
+}
+#endif

Drivers/sx126x-module/include/drivers/sx1262.h

@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: Apache-2.0
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <tactility/drivers/gpio.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** Field order must match the property order in bindings/semtech,sx1262.yaml */
+struct Sx1262Config {
+    /** Chip-select index on the parent SPI controller, must match the node's unit address */
+    int32_t reg;
+    /** SPI clock frequency in kHz */
+    uint32_t spi_frequency_khz;
+    /** NRESET line (must be an SoC GPIO) */
+    struct GpioPinSpec pin_reset;
+    /** BUSY line (must be an SoC GPIO) */
+    struct GpioPinSpec pin_busy;
+    /** DIO1 interrupt line (must be an SoC GPIO) */
+    struct GpioPinSpec pin_dio1;
+    /** Optional module power enable, driven active while the device is started */
+    struct GpioPinSpec pin_enable;
+    /** Optional antenna select, driven active while the device is started */
+    struct GpioPinSpec pin_antenna_select;
+    /** TCXO reference voltage on DIO3 in millivolts, 0 when no TCXO is fitted */
+    uint32_t tcxo_millivolts;
+    /** Use the LDO regulator instead of the DC-DC converter */
+    bool use_regulator_ldo;
+    /** DIO2 drives the antenna TX/RX switch */
+    bool dio2_as_rf_switch;
+};
+
+#ifdef __cplusplus
+}
+#endif

Drivers/sx126x-module/include/sx126x_module.h

@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: Apache-2.0
+#pragma once
+
+#include <tactility/module.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern struct Module sx126x_module;
+
+#ifdef __cplusplus
+}
+#endif