Add new port layer for CCRH U2x and GHS U2x (#16)

Co-authored-by: Duc Dat Le <[email protected]>

CCRH/U2x/README.md

@@ -0,0 +1,55 @@
+# RH850/U2x FreeRTOS Port with CC-RH Compiler
+
+## Introduction
+
+This repository contains the port of FreeRTOS for Renesas RH850/U2x microcontrollers using the CC-RH compiler. The following sections provide instructions on how to use this port, a link to the test project, and other relevant information.
+
+## Prerequisites
+- Compiler: CC-RH
+- FreeRTOS version 11.1.0
+
+| Device   | FPU | FXU | SMP |
+|----------|-----|-----|-----|
+| U2A6     | Yes | No  | Yes |
+| U2A8     | Yes | No  | Yes |
+| U2A16    | Yes | No  | Yes |
+| U2B6     | Yes | Yes | Yes |
+| U2B10    | Yes | Yes | Yes |
+
+## Link to Test Project
+
+The test project can be found in [RH850_U2Ax_CCRH](https://github.com/renesas/FreeRTOS-Partner-Supported-Demos/tree/u2x_port/) and [RH850_U2Bx_CCRH](https://github.com/renesas/FreeRTOS-Partner-Supported-Demos/tree/u2x_port/). This project contains example tasks and configurations to help you get started with FreeRTOS on the RH850/U2Ax and U2Bx.
+
+## Note
+   1. The minimal stack size (configMINIMAL_STACK_SIZE) must be included the reserved memory for nested interrupt. This formula can be referred: `(task_context_size) * (2 + configMAX_INT_NESTING) + Stack_depth_of_taskcode`
+   In which, `task_context_size` is calculated as `36*4bytes = 144bytes` (when FPU enabled) or `34*4bytes = 136` (when FPU disabled), configMAX_INT_NESTING is `02` as default (Note that a value of `0` is not allowed).
+   2. Users need to create a memory section named `mev_address` in `CRAM` for Exclusive Control functionality. Users should initialize the `mev_address` section in the startup file.
+
+Example:
+   ```
+  ; .mev_address section in CRAM is used for Sync flags
+  mov     #__s.mev_address.bss, r20
+  st.w    r0, 0[r20]
+   ```
+   3. The `FXU unit` is only available on `core 0`. Users must ensure that FXU operations are restricted to `core 0` by using the `vTaskCoreAffinitySet` function provided by FreeRTOS SMP.
+   4. FXU can be enabled by specific compiler option `-DconfigENABLE_FXU`. FPU can be enabled by specific compiler option `-DconfigENABLE_FPU`
+   5. The macros `configENABLE_FXU` and `configENABLE_FPU` must be defined in `FreeRTOSConfig.h`.
+   6. This port supports both U2Ax and U2Bx devices. The user must configure `configDEVICE_NAME` with the value `U2Bx_DEVICES` or `U2Ax_DEVICES` to specify which device is being used.
+   7. The User can configure the interrupt priority of the OSTM Timer using `configTIMER_INT_PRIORITY`, with 16 levels available (0 being the highest priority and 15 the lowest).
+   8. This port also supports the configuration of contiguous CPU cores in FreeRTOS, allowing the user to set task affinity for execution on specific cores or subsets of cores.
+
+
+## Other Relevant Information
+
+- **Documentation:**
+  - Refer to the official [FreeRTOS documentation](https://www.freertos.org/Documentation/RTOS_book.html) for detailed information on configuring and using FreeRTOS.
+  - Consult the [RH850 U2A group user manual hardware manual](https://www.renesas.com/en/document/mah/rh850u2a-eva-group-users-manual-hardware-0?r=1546621) for specific details about the microcontroller.
+  - Consult the [RH850 U2B group user manual hardware manual](https://www.renesas.com/en/document/mah/rh850u2b-flash-memory-users-manual-r01uh0927ej0100?srsltid=AfmBOooTd6sk-_EsdVV0L_Rw0vGMsaoCQ0SSzpmtoScRcxgcwVkLrQwY) for specific details about the microcontroller.
+  - For more information about Renesas RH850 microcontrolers, please visit [this website](https://www.renesas.com/us/en/products/microcontrollers-microprocessors/rh850-automotive-mcus)
+  - The CC-RH compiler can be downloaded [here](https://www.renesas.com/us/en/software-tool/c-compiler-package-rh850-family#downloads)
+
+- **Support:**
+  - If you encounter any issues or have questions about this port, please open an issue in this repository or contact the maintainer.
+
+- **Contributing:**
+  - Contributions to improve this port are welcome. Please fork the repository, make your changes, and submit a pull request.