Add esp/wdt_regs.h

core/include/esp/wdt_regs.h

@@ -0,0 +1,38 @@
+/* esp/wdt_regs.h
+ *
+ * ESP8266 Watchdog Timer register definitions
+ *
+ * Not compatible with ESP SDK register access code.
+ */
+
+#ifndef _ESP_WDT_REGS_H
+#define _ESP_WDT_REGS_H
+
+#include "esp/types.h"
+#include "common_macros.h"
+
+#define WDT_BASE 0x60000900
+#define WDT (*(struct WDT_REGS *)(WDT_BASE))
+
+/* WDT register(s)
+
+   Not fully understood yet. Writing 0 to CTRL disables WDT.
+
+   See ROM functions esp_wdt_xxx
+ */
+
+struct WDT_REGS {
+    uint32_t volatile CTRL;        // 0x00
+    uint32_t volatile REG1;        // 0x04
+    uint32_t volatile REG2;        // 0x08
+    uint32_t volatile _unused[2];  // 0x0c - 0x10
+    uint32_t volatile FEED;        // 0x14
+} __attribute__ (( packed ));
+
+_Static_assert(sizeof(struct WDT_REGS) == 0x18, "WDT_REGS is the wrong size");
+
+/* Writing WDT_FEED_MAGIC to WDT.FEED register "feeds the dog" and holds off
+ * triggering for another cycle (unconfirmed) */
+#define WDT_FEED_MAGIC  0x73
+
+#endif /* _ESP_WDT_REGS_H */