Postmortem Debugging to serial port (#20492)

Marlin/src/HAL/STM32F1/HAL.cpp

@@ -272,6 +272,8 @@ static void NVIC_SetPriorityGrouping(uint32_t PriorityGroup) {
   } }
 #endif
 
+TERN_(POSTMORTEM_DEBUGGING, extern void install_min_serial());
+
 void HAL_init() {
   NVIC_SetPriorityGrouping(0x3);
   #if PIN_EXISTS(LED)
@@ -287,6 +289,7 @@ void HAL_init() {
     delay(1000);                                         // Give OS time to notice
     OUT_WRITE(USB_CONNECT_PIN, USB_CONNECT_INVERTING);
   #endif
+  TERN_(POSTMORTEM_DEBUGGING, install_min_serial());    // Install the minimal serial handler
 }
 
 // HAL idle task

Marlin/src/HAL/STM32F1/HAL_MinSerial.cpp

@@ -0,0 +1,118 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2021 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ * Copyright (c) 2017 Victor Perez
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+#ifdef __STM32F1__
+
+#include "../../inc/MarlinConfigPre.h"
+
+#if ENABLED(POSTMORTEM_DEBUGGING)
+
+#include "../shared/HAL_MinSerial.h"
+#include "watchdog.h"
+
+#include <libmaple/usart.h>
+#include <libmaple/rcc.h>
+#include <libmaple/nvic.h>
+
+/* Instruction Synchronization Barrier */
+#define isb() __asm__ __volatile__ ("isb" : : : "memory")
+
+/* Data Synchronization Barrier */
+#define dsb() __asm__ __volatile__ ("dsb" : : : "memory")
+
+static void TXBegin() {
+  #if !WITHIN(SERIAL_PORT, 1, 6)
+    #warning "Using POSTMORTEM_DEBUGGING requires a physical U(S)ART hardware in case of severe error."
+    #warning "Disabling the severe error reporting feature currently because the used serial port is not a HW port."
+  #else
+    // We use MYSERIAL0 here, so we need to figure out how to get the linked register
+    struct usart_dev* dev = MYSERIAL0.c_dev();
+
+    // Or use this if removing libmaple
+    // int irq = dev->irq_num;
+    // int nvicUART[] = { NVIC_USART1 /* = 37 */, NVIC_USART2 /* = 38 */, NVIC_USART3 /* = 39 */, NVIC_UART4 /* = 52 */, NVIC_UART5 /* = 53 */ };
+    // Disabling irq means setting the bit in the NVIC ICER register located at
+    // Disable UART interrupt in NVIC
+    nvic_irq_disable(dev->irq_num);
+
+    // Use this if removing libmaple
+    //NVIC_BASE->ICER[1] |= _BV(irq - 32);
+
+    // We NEED memory barriers to ensure Interrupts are actually disabled!
+    // ( https://dzone.com/articles/nvic-disabling-interrupts-on-arm-cortex-m-and-the )
+    dsb();
+    isb();
+
+    rcc_clk_disable(dev->clk_id);
+    rcc_clk_enable(dev->clk_id);
+
+    usart_reg_map *regs = dev->regs;
+    regs->CR1 = 0; // Reset the USART
+    regs->CR2 = 0; // 1 stop bit
+
+    // If we don't touch the BRR (baudrate register), we don't need to recompute. Else we would need to call
+    usart_set_baud_rate(dev, 0, BAUDRATE);
+
+    regs->CR1 = (USART_CR1_TE | USART_CR1_UE); // 8 bits, no parity, 1 stop bit
+  #endif
+}
+
+// A SW memory barrier, to ensure GCC does not overoptimize loops
+#define sw_barrier() __asm__ volatile("": : :"memory");
+static void TX(char c) {
+  #if WITHIN(SERIAL_PORT, 1, 6)
+    struct usart_dev* dev = MYSERIAL0.c_dev();
+    while (!(dev->regs->SR & USART_SR_TXE)) {
+      TERN_(USE_WATCHDOG, HAL_watchdog_refresh());
+      sw_barrier();
+    }
+    dev->regs->DR = c;
+  #endif
+}
+
+void install_min_serial() {
+  HAL_min_serial_init = &TXBegin;
+  HAL_min_serial_out = &TX;
+}
+
+#if DISABLED(DYNAMIC_VECTORTABLE) && DISABLED(STM32F0xx) // Cortex M0 can't branch to a symbol that's too far, so we have a specific hack for them
+extern "C" {
+  __attribute__((naked)) void JumpHandler_ASM() {
+    __asm__ __volatile__ (
+      "b CommonHandler_ASM\n"
+    );
+  }
+  void __attribute__((naked, alias("JumpHandler_ASM"), nothrow)) __exc_hardfault();
+  void __attribute__((naked, alias("JumpHandler_ASM"), nothrow)) __exc_busfault();
+  void __attribute__((naked, alias("JumpHandler_ASM"), nothrow)) __exc_usagefault();
+  void __attribute__((naked, alias("JumpHandler_ASM"), nothrow)) __exc_memmanage();
+  void __attribute__((naked, alias("JumpHandler_ASM"), nothrow)) __exc_nmi();
+  void __attribute__((naked, alias("JumpHandler_ASM"), nothrow)) __stm32reservedexception7();
+  void __attribute__((naked, alias("JumpHandler_ASM"), nothrow)) __stm32reservedexception8();
+  void __attribute__((naked, alias("JumpHandler_ASM"), nothrow)) __stm32reservedexception9();
+  void __attribute__((naked, alias("JumpHandler_ASM"), nothrow)) __stm32reservedexception10();
+  void __attribute__((naked, alias("JumpHandler_ASM"), nothrow)) __stm32reservedexception13();
+}
+#endif
+
+#endif // POSTMORTEM_DEBUGGING
+#endif // __STM32F1__

Marlin/src/HAL/STM32F1/inc/SanityCheck.h

@@ -34,9 +34,9 @@
 #endif
 
 #if ENABLED(SERIAL_STATS_MAX_RX_QUEUED)
-  #error "SERIAL_STATS_MAX_RX_QUEUED is not supported on this platform."
+  #error "SERIAL_STATS_MAX_RX_QUEUED is not supported on the STM32F1 platform."
 #elif ENABLED(SERIAL_STATS_DROPPED_RX)
-  #error "SERIAL_STATS_DROPPED_RX is not supported on this platform."
+  #error "SERIAL_STATS_DROPPED_RX is not supported on the STM32F1 platform."
 #endif
 
 #if ENABLED(NEOPIXEL_LED)