LoRa device type + SX1262 kernel driver (first checkpoint)

Devices/lilygo-tdeck-max/devicetree.yaml

@@ -1,4 +1,5 @@
 dependencies:
   - Platforms/platform-esp32
+  - Drivers/sx126x-module
   - Drivers/xl9555-module
 dts: lilygo,tdeck-max.dts

Devices/lilygo-tdeck-max/lilygo,tdeck-max.dts

@@ -7,6 +7,7 @@
 #include <tactility/bindings/esp32_i2c_master.h>
 #include <tactility/bindings/esp32_spi.h>
 #include <tactility/bindings/esp32_sdspi.h>
+#include <bindings/sx1262.h>
 #include <bindings/xl9555.h>
 
 // Reference: https://github.com/Xinyuan-LilyGO/T-Deck-MAX
@@ -47,7 +48,7 @@
 		host = <SPI2_HOST>;
 		cs-gpios = <&gpio0 34 GPIO_FLAG_NONE>, // 0: EPD display
 		           <&gpio0 48 GPIO_FLAG_NONE>, // 1: SD card
-		           <&gpio0 3 GPIO_FLAG_NONE>;  // 2: LoRa radio (SX1262, not wired up yet)
+		           <&gpio0 3 GPIO_FLAG_NONE>;  // 2: LoRa radio (SX1262)
 		pin-mosi = <&gpio0 33 GPIO_FLAG_NONE>;
 		pin-miso = <&gpio0 47 GPIO_FLAG_NONE>;
 		pin-sclk = <&gpio0 36 GPIO_FLAG_NONE>;
@@ -60,5 +61,22 @@
 			status = "disabled";
 			frequency-khz = <20000>;
 		};
+
+		// SX1262 LoRa transceiver, wired per the vendor docs/pinmap.md and
+		// examples/LoRa_sx1262: CS/RST/DIO1/BUSY = GPIO 3/4/5/6, TCXO 2.4 V,
+		// DIO2 drives the antenna TX/RX switch. Module power (LORA_EN, P01)
+		// and antenna select (LORA_SEL, P04: high = internal antenna) are
+		// gated by the XL9555 IO expander.
+		radio@2 {
+			compatible = "semtech,sx1262";
+			reg = <2>;
+			pin-reset = <&gpio0 4 GPIO_FLAG_NONE>;
+			pin-dio1 = <&gpio0 5 GPIO_FLAG_NONE>;
+			pin-busy = <&gpio0 6 GPIO_FLAG_NONE>;
+			pin-enable = <&xl9555 1 GPIO_FLAG_NONE>;
+			pin-antenna-select = <&xl9555 4 GPIO_FLAG_NONE>;
+			tcxo-millivolts = <2400>;
+			dio2-as-rf-switch;
+		};
 	};
 };

Drivers/sx126x-module/CMakeLists.txt

@@ -0,0 +1,12 @@
+cmake_minimum_required(VERSION 3.20)
+
+include("${CMAKE_CURRENT_LIST_DIR}/../../Buildscripts/module.cmake")
+
+file(GLOB_RECURSE SOURCE_FILES "source/*.c*" "private/*.c*")
+
+tactility_add_module(sx126x-module
+    SRCS ${SOURCE_FILES}
+    INCLUDE_DIRS include/
+    PRIV_INCLUDE_DIRS private/
+    REQUIRES TactilityKernel platform-esp32 radiolib driver esp_timer
+)

Drivers/sx126x-module/LICENSE-Apache-2.0.md

@@ -0,0 +1,195 @@
+Apache License
+==============
+
+_Version 2.0, January 2004_  
+_&lt;<http://www.apache.org/licenses/>&gt;_
+
+### Terms and Conditions for use, reproduction, and distribution
+
+#### 1. Definitions
+
+“License” shall mean the terms and conditions for use, reproduction, and
+distribution as defined by Sections 1 through 9 of this document.
+
+“Licensor” shall mean the copyright owner or entity authorized by the copyright
+owner that is granting the License.
+
+“Legal Entity” shall mean the union of the acting entity and all other entities
+that control, are controlled by, or are under common control with that entity.
+For the purposes of this definition, “control” means **(i)** the power, direct or
+indirect, to cause the direction or management of such entity, whether by
+contract or otherwise, or **(ii)** ownership of fifty percent (50%) or more of the
+outstanding shares, or **(iii)** beneficial ownership of such entity.
+
+“You” (or “Your”) shall mean an individual or Legal Entity exercising
+permissions granted by this License.
+
+“Source” form shall mean the preferred form for making modifications, including
+but not limited to software source code, documentation source, and configuration
+files.
+
+“Object” form shall mean any form resulting from mechanical transformation or
+translation of a Source form, including but not limited to compiled object code,
+generated documentation, and conversions to other media types.
+
+“Work” shall mean the work of authorship, whether in Source or Object form, made
+available under the License, as indicated by a copyright notice that is included
+in or attached to the work (an example is provided in the Appendix below).
+
+“Derivative Works” shall mean any work, whether in Source or Object form, that
+is based on (or derived from) the Work and for which the editorial revisions,
+annotations, elaborations, or other modifications represent, as a whole, an
+original work of authorship. For the purposes of this License, Derivative Works
+shall not include works that remain separable from, or merely link (or bind by
+name) to the interfaces of, the Work and Derivative Works thereof.
+
+“Contribution” shall mean any work of authorship, including the original version
+of the Work and any modifications or additions to that Work or Derivative Works
+thereof, that is intentionally submitted to Licensor for inclusion in the Work
+by the copyright owner or by an individual or Legal Entity authorized to submit
+on behalf of the copyright owner. For the purposes of this definition,
+“submitted” means any form of electronic, verbal, or written communication sent
+to the Licensor or its representatives, including but not limited to
+communication on electronic mailing lists, source code control systems, and
+issue tracking systems that are managed by, or on behalf of, the Licensor for
+the purpose of discussing and improving the Work, but excluding communication
+that is conspicuously marked or otherwise designated in writing by the copyright
+owner as “Not a Contribution.”
+
+“Contributor” shall mean Licensor and any individual or Legal Entity on behalf
+of whom a Contribution has been received by Licensor and subsequently
+incorporated within the Work.
+
+#### 2. Grant of Copyright License
+
+Subject to the terms and conditions of this License, each Contributor hereby
+grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free,
+irrevocable copyright license to reproduce, prepare Derivative Works of,
+publicly display, publicly perform, sublicense, and distribute the Work and such
+Derivative Works in Source or Object form.
+
+#### 3. Grant of Patent License
+
+Subject to the terms and conditions of this License, each Contributor hereby
+grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free,
+irrevocable (except as stated in this section) patent license to make, have
+made, use, offer to sell, sell, import, and otherwise transfer the Work, where
+such license applies only to those patent claims licensable by such Contributor
+that are necessarily infringed by their Contribution(s) alone or by combination
+of their Contribution(s) with the Work to which such Contribution(s) was
+submitted. If You institute patent litigation against any entity (including a
+cross-claim or counterclaim in a lawsuit) alleging that the Work or a
+Contribution incorporated within the Work constitutes direct or contributory
+patent infringement, then any patent licenses granted to You under this License
+for that Work shall terminate as of the date such litigation is filed.
+
+#### 4. Redistribution
+
+You may reproduce and distribute copies of the Work or Derivative Works thereof
+in any medium, with or without modifications, and in Source or Object form,
+provided that You meet the following conditions:
+
+* **(a)** You must give any other recipients of the Work or Derivative Works a copy of
+this License; and
+* **(b)** You must cause any modified files to carry prominent notices stating that You
+changed the files; and
+* **(c)** You must retain, in the Source form of any Derivative Works that You distribute,
+all copyright, patent, trademark, and attribution notices from the Source form
+of the Work, excluding those notices that do not pertain to any part of the
+Derivative Works; and
+* **(d)** If the Work includes a “NOTICE” text file as part of its distribution, then any
+Derivative Works that You distribute must include a readable copy of the
+attribution notices contained within such NOTICE file, excluding those notices
+that do not pertain to any part of the Derivative Works, in at least one of the
+following places: within a NOTICE text file distributed as part of the
+Derivative Works; within the Source form or documentation, if provided along
+with the Derivative Works; or, within a display generated by the Derivative
+Works, if and wherever such third-party notices normally appear. The contents of
+the NOTICE file are for informational purposes only and do not modify the
+License. You may add Your own attribution notices within Derivative Works that
+You distribute, alongside or as an addendum to the NOTICE text from the Work,
+provided that such additional attribution notices cannot be construed as
+modifying the License.
+
+You may add Your own copyright statement to Your modifications and may provide
+additional or different license terms and conditions for use, reproduction, or
+distribution of Your modifications, or for any such Derivative Works as a whole,
+provided Your use, reproduction, and distribution of the Work otherwise complies
+with the conditions stated in this License.
+
+#### 5. Submission of Contributions
+
+Unless You explicitly state otherwise, any Contribution intentionally submitted
+for inclusion in the Work by You to the Licensor shall be under the terms and
+conditions of this License, without any additional terms or conditions.
+Notwithstanding the above, nothing herein shall supersede or modify the terms of
+any separate license agreement you may have executed with Licensor regarding
+such Contributions.
+
+#### 6. Trademarks
+
+This License does not grant permission to use the trade names, trademarks,
+service marks, or product names of the Licensor, except as required for
+reasonable and customary use in describing the origin of the Work and
+reproducing the content of the NOTICE file.
+
+#### 7. Disclaimer of Warranty
+
+Unless required by applicable law or agreed to in writing, Licensor provides the
+Work (and each Contributor provides its Contributions) on an “AS IS” BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied,
+including, without limitation, any warranties or conditions of TITLE,
+NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are
+solely responsible for determining the appropriateness of using or
+redistributing the Work and assume any risks associated with Your exercise of
+permissions under this License.
+
+#### 8. Limitation of Liability
+
+In no event and under no legal theory, whether in tort (including negligence),
+contract, or otherwise, unless required by applicable law (such as deliberate
+and grossly negligent acts) or agreed to in writing, shall any Contributor be
+liable to You for damages, including any direct, indirect, special, incidental,
+or consequential damages of any character arising as a result of this License or
+out of the use or inability to use the Work (including but not limited to
+damages for loss of goodwill, work stoppage, computer failure or malfunction, or
+any and all other commercial damages or losses), even if such Contributor has
+been advised of the possibility of such damages.
+
+#### 9. Accepting Warranty or Additional Liability
+
+While redistributing the Work or Derivative Works thereof, You may choose to
+offer, and charge a fee for, acceptance of support, warranty, indemnity, or
+other liability obligations and/or rights consistent with this License. However,
+in accepting such obligations, You may act only on Your own behalf and on Your
+sole responsibility, not on behalf of any other Contributor, and only if You
+agree to indemnify, defend, and hold each Contributor harmless for any liability
+incurred by, or claims asserted against, such Contributor by reason of your
+accepting any such warranty or additional liability.
+
+_END OF TERMS AND CONDITIONS_
+
+### APPENDIX: How to apply the Apache License to your work
+
+To apply the Apache License to your work, attach the following boilerplate
+notice, with the fields enclosed by brackets `[]` replaced with your own
+identifying information. (Don't include the brackets!) The text should be
+enclosed in the appropriate comment syntax for the file format. We also
+recommend that a file or class name and description of purpose be included on
+the same “printed page” as the copyright notice for easier identification within
+third-party archives.
+
+    Copyright [yyyy] [name of copyright owner]
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+

Drivers/sx126x-module/README.md

@@ -0,0 +1,69 @@
+# SX126x driver module
+
+Kernel driver for the Semtech SX1262 sub-GHz LoRa and (G)FSK transceiver, built on
+[RadioLib](https://github.com/jgromes/RadioLib). It registers a `lora` device
+(see `<tactility/drivers/lora.h>`) that supports LoRa and FSK for TX/RX and LR-FHSS for TX.
+
+The device is a child of an SPI controller. The chip-select line comes from the parent's
+`cs-gpios` entry matching the node's unit address; the `reg` property must match that
+unit address (checked at device start). The reset, busy and DIO1 lines must be
+SoC GPIOs (the RadioLib HAL drives them directly); the optional enable and antenna-select
+lines can live on any GPIO controller, including IO expanders, and are driven to their
+active level while the device is started.
+
+Example (LilyGO T-Deck Max):
+
+```dts
+spi0 {
+    compatible = "espressif,esp32-spi";
+    cs-gpios = <&gpio0 34 GPIO_FLAG_NONE>, // 0: EPD display
+               <&gpio0 48 GPIO_FLAG_NONE>, // 1: SD card
+               <&gpio0 3 GPIO_FLAG_NONE>;  // 2: LoRa radio (SX1262)
+    /* ... */
+
+    radio@2 {
+        compatible = "semtech,sx1262";
+        reg = <2>;
+        pin-reset = <&gpio0 4 GPIO_FLAG_NONE>;
+        pin-dio1 = <&gpio0 5 GPIO_FLAG_NONE>;
+        pin-busy = <&gpio0 6 GPIO_FLAG_NONE>;
+        pin-enable = <&xl9555 1 GPIO_FLAG_NONE>;
+        pin-antenna-select = <&xl9555 4 GPIO_FLAG_NONE>;
+        tcxo-millivolts = <2400>;
+        dio2-as-rf-switch;
+    };
+};
+```
+
+Notes:
+
+- Starting the device selects the antenna path, powers the module and runs a GPIO-only
+  probe (reset pulse, then wait for the chip to drive BUSY low), so an absent or
+  unpowered module fails at device start. The modem itself is initialized when the
+  radio is enabled via `lora_set_enabled()`, which requires a modulation to be set first.
+- Bus sharing: RadioLib drives the chip-select manually across multiple transfers, so
+  each exchange must be atomic on the bus. It runs inside two nested locks — the kernel
+  SPI controller lock (`spi_controller_lock`, the arbiter other kernel drivers on the
+  host cooperate through) as the outer lock, and ESP-IDF's per-host bus lock
+  (`spi_device_acquire_bus`) as the inner one, which additionally blocks the IDF-managed
+  spi_master devices (displays, SD cards) that don't take the controller lock.
+- TX-done is waited for using the packet's time-on-air plus a fixed margin, so slow
+  configurations (high spreading factor / narrow bandwidth) don't false-time-out.
+- Over-current protection defaults to RadioLib's fail-safe 60 mA, which caps the PA
+  current into a bad or disconnected antenna but also caps output below +22 dBm. A
+  board-aware consumer that knows its antenna and PA can raise it via
+  `LORA_PARAMETER_CURRENT_LIMIT` (up to 140 mA) to reach full output power.
+- Radio activity is logged at INFO level (state changes, modem config, TX/RX events);
+  per-call detail sits at DEBUG, which is compiled out unless the sdkconfig log level
+  is raised.
+
+## Roadmap / not yet implemented
+
+- FSK addressed transmission is not exposed through the lora API yet.
+- Antenna-presence detection. The SX1262 has no hardware antenna-detect pin (unlike, e.g.,
+  the u-blox SARA modules' dedicated ANT_DET ADC circuit), and the T-Deck Max antenna
+  connector is not hot-swap-rated. The intended approach is a software heuristic on the
+  radio thread — watching the RX noise floor / RSSI for the signature of a
+  disconnected/open PA load and disabling TX at the driver layer when detected — so the
+  protection lives below the app/OS. This is unproven and deliberately not built yet;
+  feedback on the method is welcome before implementing it.

Drivers/sx126x-module/bindings/semtech,sx1262.yaml

@@ -0,0 +1,47 @@
+description: Semtech SX1262 sub-GHz LoRa and (G)FSK transceiver
+
+compatible: "semtech,sx1262"
+
+bus: spi
+
+properties:
+  reg:
+    type: int
+    required: true
+    description: Chip-select index on the parent SPI controller, must match the node's unit address
+  spi-frequency-khz:
+    type: int
+    default: 4000
+    description: SPI clock frequency in kHz
+  pin-reset:
+    type: phandles
+    required: true
+    description: NRESET line (must be an SoC GPIO)
+  pin-busy:
+    type: phandles
+    required: true
+    description: BUSY line (must be an SoC GPIO)
+  pin-dio1:
+    type: phandles
+    required: true
+    description: DIO1 interrupt line (must be an SoC GPIO)
+  pin-enable:
+    type: phandles
+    default: GPIO_PIN_SPEC_NONE
+    description: Optional module power enable, driven active while the device is started (any GPIO controller)
+  pin-antenna-select:
+    type: phandles
+    default: GPIO_PIN_SPEC_NONE
+    description: Optional antenna select, driven active while the device is started (any GPIO controller)
+  tcxo-millivolts:
+    type: int
+    default: 0
+    description: TCXO reference voltage on DIO3 in millivolts, 0 when no TCXO is fitted
+  use-regulator-ldo:
+    type: boolean
+    default: false
+    description: Use the LDO regulator instead of the DC-DC converter
+  dio2-as-rf-switch:
+    type: boolean
+    default: false
+    description: DIO2 drives the antenna TX/RX switch

Drivers/sx126x-module/devicetree.yaml

@@ -0,0 +1,3 @@
+dependencies:
+  - TactilityKernel
+bindings: bindings

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