Add getResetReason() by palmerr23 (#2516)

* Add support for RP2350

cores/rp2040/RP2040Support.h

@@ -22,6 +22,11 @@
 #include <hardware/irq.h>
 #include <hardware/pio.h>
 #include <pico/unique_id.h>
+#ifdef PICO_RP2350
+#include <hardware/regs/powman.h>
+#else
+#include <hardware/regs/vreg_and_chip_reset.h>
+#endif
 #include <hardware/exception.h>
 #include <hardware/watchdog.h>
 #include <hardware/structs/rosc.h>
@@ -352,6 +357,61 @@ public:
         watchdog_update();
     }
 
+    enum resetReason_t {UNKNOWN_RESET, PWRON_RESET, RUN_PIN_RESET, SOFT_RESET, WDT_RESET, DEBUG_RESET, GLITCH_RESET, BROWNOUT_RESET};
+
+    resetReason_t getResetReason(void) {
+        io_rw_32 *WD_reason_reg = (io_rw_32 *)(WATCHDOG_BASE + WATCHDOG_REASON_OFFSET);
+
+        if (watchdog_caused_reboot() && watchdog_enable_caused_reboot()) { // watchdog timer
+            return WDT_RESET;
+        }
+
+        if (*WD_reason_reg & WATCHDOG_REASON_TIMER_BITS) { // soft reset() or reboot()
+            return SOFT_RESET;
+        }
+
+#ifdef PICO_RP2350
+        // **** RP2350 is untested ****
+        io_rw_32 *rrp = (io_rw_32 *)(POWMAN_BASE + POWMAN_CHIP_RESET_OFFSET);
+
+        if (*rrp & POWMAN_CHIP_RESET_HAD_POR_BITS) { // POR: power-on reset (brownout is separately detected on RP2350)
+            return PWRON_RESET;
+        }
+
+        if (*rrp & POWMAN_CHIP_RESET_HAD_RUN_LOW_BITS) { // RUN pin
+            return RUN_PIN_RESET;
+        }
+
+        if ((*rrp & POWMAN_CHIP_RESET_HAD_DP_RESET_REQ_BITS) || (*rrp & POWMAN_CHIP_RESET_HAD_RESCUE_BITS) || (*rrp & POWMAN_CHIP_RESET_HAD_HZD_SYS_RESET_REQ_BITS)) { // DEBUG port
+            return DEBUG_RESET;
+        }
+
+        if (*rrp & POWMAN_CHIP_RESET_HAD_GLITCH_DETECT_BITS) { // power supply glitch
+            return GLITCH_RESET;
+        }
+
+        if (*rrp & POWMAN_CHIP_RESET_HAD_BOR_BITS) { // power supply brownout reset
+            return BROWNOUT_RESET;
+        }
+
+#else
+        io_rw_32 *rrp = (io_rw_32 *)(VREG_AND_CHIP_RESET_BASE + VREG_AND_CHIP_RESET_CHIP_RESET_OFFSET);
+
+        if (*rrp & VREG_AND_CHIP_RESET_CHIP_RESET_HAD_POR_BITS) { // POR: power-on reset or brown-out detection
+            return PWRON_RESET;
+        }
+
+        if (*rrp & VREG_AND_CHIP_RESET_CHIP_RESET_HAD_RUN_BITS) { // RUN pin
+            return RUN_PIN_RESET;
+        }
+
+        if (*rrp & VREG_AND_CHIP_RESET_CHIP_RESET_HAD_PSM_RESTART_BITS) { // DEBUG port
+            return DEBUG_RESET; // **** untested **** debug reset may just cause a rebootToBootloader()
+        }
+#endif
+        return UNKNOWN_RESET;
+    }
+
     const char *getChipID() {
         static char id[2 * PICO_UNIQUE_BOARD_ID_SIZE_BYTES + 1] = { 0 };
         if (!id[0]) {

docs/rp2040.rst

@@ -57,6 +57,11 @@ void rp2040.wdt_reset()
 ~~~~~~~~~~~~~~~~~~~~~~~
 Reloads the watchdog's counter with the amount of time set by wdt_begin.
 
+RP2040::resetReason_t rp2040.getResetReason()
+~~~~~~~~~~~~~~~~~~~~~~~
+Returns the reason for the last reset, defined in enum ``RP2040::resetReason_t``.
+See example ```ResetReason``` for some details.
+
 
 Memory Information
 ------------------

libraries/rp2040/examples/RestartReason/RestartReason.ino

@@ -0,0 +1,68 @@
+// This sketch will cycle thru some possible restart reasons and shall help you understanding the rp2040.getResetReason() function
+// Author: palmerr23
+
+#include <EEPROM.h>
+#define NTESTS 5  // Number of tests, Debug port test not enabled
+char resetReasonText[][24] = { "Unknown", "Power On / Brownout", "Run pin", "Software", "Watchdog Timer", "Debug reset" };
+char testText[][128] = { "Run pin\n\tShort Run pin to ground", "Power On / Brownout\n\tDisconnect / reconnect power (i.e. USB)", "Software reBOOT in 5 Secs", "Watchdog Timer in 7 Secs", "Software reSTART in 5 Secs\n\tUSB Serial does not always restart", "Debug port - do something!" };
+
+// Small function that will send one dot every second over Serial, forever.
+void delayCount(void) {
+  int t = 1;
+  while (1) {
+    Serial.print(".");
+    if (t % 50 == 0) {
+      Serial.println();
+    }
+    delay(1000);
+  }
+}
+
+void setup() {
+  Serial.begin(115200);
+  while (!Serial) {
+    delay(10);
+  }
+  delay(1000);
+  Serial.println("Reset reason:");
+
+  RP2040::resetReason_t rr = rp2040.getResetReason();
+  Serial.printf("RR %i %s\n\n", rr, resetReasonText[rr]);
+
+  EEPROM.begin(512);
+  byte test = EEPROM.read(0);
+  if (test >= NTESTS) {  // un-initialised EEPROM read is random
+    test = -1;
+  }
+  test = (test + 1) % NTESTS; // Go to next test, but limit to NTESTS-1
+  Serial.printf("Test %i: %s\n", test, testText[test]);
+  EEPROM.write(0, test);
+  EEPROM.commit();
+  delay(5000);
+  switch (test) {
+    case 0:  //  Run pin
+      delayCount();
+      break;  // Break to avoid compiler warnings
+    case 1:   // Power On
+      delayCount();
+      break;
+    case 2:  // reboot command
+      rp2040.reboot();
+      delayCount();
+      break;
+    case 3:  // watchdog
+      rp2040.wdt_begin(2000);
+      rp2040.wdt_reset();
+      delayCount();
+      break;
+    case 4:  // restart command
+      rp2040.restart();
+      delayCount();
+      break;
+  }
+}
+
+// never gets here
+void loop() {
+  delay(100);
+}