[realtek-ambz2] Fix C++ support, implement SerialClass

builder/family/realtek-ambz2.py

@@ -53,7 +53,7 @@ queue.AppendPublic(
         "-mthumb",
         "-mcmse",
         "-mfloat-abi=soft",
-        "--specs=nosys.specs",
+        "--specs=nano.specs",
         "-Wl,--use-blx",
         "-Wl,--undefined=gRamStartFun",
         "-Wl,-wrap,aesccmp_construct_mic_iv",

cores/realtek-ambz2/arduino/libraries/Serial/Serial.cpp

@@ -0,0 +1,94 @@
+/* Copyright (c) Kuba Szczodrzyński 2023-05-24. */
+
+#include "SerialPrivate.h"
+
+#if HAS_SERIAL0
+SerialClass Serial0(0, PIN_SERIAL0_RX, PIN_SERIAL0_TX);
+#endif
+#if HAS_SERIAL1
+SerialClass Serial1(1, PIN_SERIAL1_RX, PIN_SERIAL1_TX);
+#endif
+#if HAS_SERIAL2
+SerialClass Serial2(2, PIN_SERIAL2_RX, PIN_SERIAL2_TX);
+#endif
+
+static void callback(uint32_t param, uint32_t event) {
+	if (event != RxIrq)
+		return;
+	hal_uart_adapter_t *uart = &pdUART;
+
+	uint8_t c;
+	while (hal_uart_rgetc(uart, (char *)&c)) {
+#if LT_AUTO_DOWNLOAD_REBOOT && defined(LT_UART_ADR_PATTERN) && PIN_SERIAL2_RX != PIN_INVALID
+		// parse UART protocol commands on UART2
+		if (uart->base_addr == UART2)
+			SerialClass::adrParse(c);
+#endif
+		pdBUF.store_char(c);
+	}
+}
+
+void SerialClass::begin(unsigned long baudrate, uint16_t config) {
+	if (!this->data) {
+		this->data = new SerialData();
+		this->buf  = &BUF;
+
+		if (this->port == 2) {
+			hal_uart_deinit(&log_uart);
+		}
+
+		// TODO handle PIN_INVALID
+		hal_uart_init(&UART, this->tx, this->rx, NULL);
+
+		if (this->rx != PIN_INVALID) {
+			hal_uart_enter_critical();
+			hal_uart_rxind_hook(&UART, callback, (uint32_t)this->data, RxIrq);
+			UART.base_addr->ier_b.erbi	= 1;
+			UART.base_addr->ier_b.etbei = 0;
+			hal_uart_exit_critical();
+		}
+	}
+
+	if (this->baudrate != baudrate || this->config != config)
+		this->configure(baudrate, config);
+}
+
+void SerialClass::configure(unsigned long baudrate, uint16_t config) {
+	if (!this->data)
+		return;
+
+	uint8_t dataWidth = (config & SERIAL_DATA_MASK) == SERIAL_DATA_7 ? 7 : 8;
+	uint8_t parity	  = (config & SERIAL_PARITY_MASK) ^ 0b11;
+	uint8_t stopBits  = (config & SERIAL_STOP_BIT_MASK) == SERIAL_STOP_BIT_2 ? 2 : 1;
+
+	hal_uart_set_baudrate(&UART, baudrate);
+	hal_uart_set_format(&UART, dataWidth, parity, stopBits);
+
+	this->baudrate = baudrate;
+	this->config   = config;
+}
+
+void SerialClass::end() {
+	if (!this->data)
+		return;
+
+	hal_uart_deinit(&UART);
+
+	this->buf	   = NULL;
+	this->baudrate = 0;
+	delete DATA;
+}
+
+void SerialClass::flush() {
+	if (!this->data)
+		return;
+	while (UART.base_addr->tflvr_b.tx_fifo_lv != 0) {}
+}
+
+size_t SerialClass::write(uint8_t c) {
+	if (!this->data)
+		return 0;
+	while (!hal_uart_writeable(&UART)) {}
+	hal_uart_putc(&UART, c);
+	return 1;
+}

cores/realtek-ambz2/arduino/libraries/Serial/SerialPrivate.h

@@ -0,0 +1,18 @@
+/* Copyright (c) Kuba Szczodrzyński 2023-05-24. */
+
+#pragma once
+
+#include <Arduino.h>
+#include <sdk_private.h>
+
+typedef struct {
+	hal_uart_adapter_t uart;
+	RingBuffer buf;
+} SerialData;
+
+#define DATA   ((SerialData *)data)
+#define pDATA  ((SerialData *)param)
+#define BUF	   (DATA->buf)
+#define pdBUF  (pDATA->buf)
+#define UART   (DATA->uart)
+#define pdUART (pDATA->uart)

cores/realtek-ambz2/arduino/src/lt_defs.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#error "Don't include this file directly"
+
+#define LT_ARD_HAS_SERIAL 1
+
+#define LT_ARD_MD5_MBEDTLS 1

cores/realtek-ambz2/base/lt_family.h

@@ -16,3 +16,7 @@
 #error "No serial port is available"
 #endif
 #endif
+
+// Auto-download-reboot detection pattern
+// "ping" command for BootROM
+#define LT_UART_ADR_PATTERN 'p', 'i', 'n', 'g', '\n'

cores/realtek-ambz2/base/port/printf.c

@@ -19,7 +19,7 @@ void putchar_(char c) {
 }
 
 void putchar_p(char c, unsigned long port) {
-	while ((uart_dev[port]->tflvr & 0x1F) > 15) {}
+	while (uart_dev[port]->tflvr_b.tx_fifo_lv >= Uart_Tx_FIFO_Size) {}
 	uart_dev[port]->thr = c;
 }
 

cores/realtek-ambz2/base/sdk_extern.h

@@ -10,6 +10,7 @@ extern "C" {
 #endif // __cplusplus
 
 // SDK
+extern hal_uart_adapter_t log_uart;
 void software_reset();
 void sys_swd_off();
 void sys_uart_download_mode();

cores/realtek-ambz2/misc/rtl8710c_ram.ld

@@ -134,26 +134,6 @@ SECTIONS
 		*(.sram.data*)
 		*(.data*)
 
-		. = ALIGN(4);
-		/* preinit data */
-		PROVIDE_HIDDEN (__preinit_array_start = .);
-		KEEP(*(.preinit_array))
-		PROVIDE_HIDDEN (__preinit_array_end = .);
-
-		. = ALIGN(4);
-		/* init data */
-		PROVIDE_HIDDEN (__init_array_start = .);
-		KEEP(*(SORT(.init_array.*)))
-		KEEP(*(.init_array))
-		PROVIDE_HIDDEN (__init_array_end = .);
-
-		. = ALIGN(4);
-		/* finit data */
-		PROVIDE_HIDDEN (__fini_array_start = .);
-		KEEP(*(SORT(.fini_array.*)))
-		KEEP(*(.fini_array))
-		PROVIDE_HIDDEN (__fini_array_end = .);
-
 		KEEP(*(.jcr*))
 		. = ALIGN(4);
 		/* All data end */
@@ -282,29 +262,6 @@ SECTIONS
 		/* put RO data sections need to be encrypted here */
 		*(.xip.sec_rodata*)
 
-		/* Add This for C++ support */
-		/* ambd_arduino/Arduino_package/hardware/variants/rtl8720dn_bw16/linker_scripts/gcc/rlx8721d_img2_is_arduino.ld */
-		. = ALIGN(4);
-		__preinit_array_start = .;
-		KEEP(*(.preinit_array))
-		__preinit_array_end = .;
-		. = ALIGN(4);
-		__init_array_start = .;
-		KEEP(*(SORT(.init_array.*)))
-		KEEP(*(.init_array))
-		__init_array_end = .;
-		. = ALIGN(4);
-		__fini_array_start = .;
-		KEEP(*(SORT(.fini_array.*)))
-		KEEP(*(.fini_array))
-		__fini_array_end = .;
-		/*-----------------*/
-		/* https://community.silabs.com/s/article/understand-the-gnu-linker-script-of-cortex-m4?language=en_US */
-		KEEP(*(.init))
-		KEEP(*(.fini))
-		*(.init)
-		*(.fini)
-
 		__xip_code_text_end__ = .;
 	} > XIP_FLASH_C
 
@@ -330,6 +287,30 @@ SECTIONS
 		KEEP(*crtend.o(.dtors))
 		*(.rodata .rodata.* .gnu.linkonce.r.*)
 
+		/* Add This for C++ support */
+		/* ambd_arduino/Arduino_package/hardware/variants/rtl8720dn_bw16/linker_scripts/gcc/rlx8721d_img2_is_arduino.ld */
+		. = ALIGN(4);
+		__preinit_array_start = .;
+		KEEP(*(.preinit_array))
+		__preinit_array_end = .;
+		. = ALIGN(4);
+		__init_array_start = .;
+		KEEP(*(SORT(.init_array.*)))
+		KEEP(*(.init_array))
+		__init_array_end = .;
+		. = ALIGN(4);
+		__fini_array_start = .;
+		KEEP(*(SORT(.fini_array.*)))
+		KEEP(*(.fini_array))
+		__fini_array_end = .;
+		/*-----------------*/
+
+		/* https://community.silabs.com/s/article/understand-the-gnu-linker-script-of-cortex-m4?language=en_US */
+		KEEP(*(.init))
+		KEEP(*(.fini))
+		*(.init)
+		*(.fini)
+
 		. = ALIGN(4);
 		__xip_code_rodata_end__ = .;
 	} > XIP_FLASH_P

docs/contrib/porting.md

@@ -50,6 +50,7 @@ Here's what has to be done to make that work:
 	- Make sure not to make a mess in the `CCFLAGS`/`CPPDEFINES`, and only include what's needed there. Some flags are project-wide (family-independent) in `builder/frameworks/base.py`.
 	- Use a **pure PlatformIO** project - **not ESPHome!**. Pass one of the generic boards you created before, and `framework = base` in `platformio.ini`. Generally, try to get the thing to compile.
 	- Use a simple Hello World program - C, not C++. Only add `main()` function with a `printf()` and a `while(1)` loop.
+	- I've noticed that using `nano.specs` instead of `nosys.specs` produces smaller binaries.
 
 9. When you get it to link successfully, build a UF2 file.
 
@@ -91,3 +92,9 @@ Here's what has to be done to make that work:
 5. Write LibreTiny C APIs - in `lt_api.c`.
 
 6. At this point, your Hello World code should work fine.
+
+## Porting Arduino Core - C++ support
+
+1. Add main.cpp and write wiring_*.c ports. GPIOs and stuff should work even without proper C++ support.
+
+2. Port Serial library first. This should already show whether C++ works fine or if it doesn't. For example, calling `Serial.println()` refers to the virtual function `Print::write`, which will probably crash the chip if C++ is not being linked properly.

docs/flashing/tools/adr.md

@@ -16,3 +16,7 @@ The code listens on UART1 for a link-check command (`01 E0 FC 01 00`). The baudr
 ## Realtek AmebaZ
 
 This only works when using [ltchiptool](ltchiptool.md) for flashing. Upon starting UART communication, the tool sends `55 AA 22 E0 D6 FC` (0x55AA followed by the `realtek-ambz` family ID). After detecting that pattern, the chip proceeds to reboot into UART download mode (using [`lt_reboot_download_mode()`](../../../ltapi/lt__device_8h.md))
+
+## Realtek AmebaZ2
+
+The code listens on UART2 for a `ping\n` command, that is sent by [ltchiptool](ltchiptool.md) (and possibly by the vendor flasher, too). The device is then rebooted to download mode.