embed: add shutdown function to fatal_error

embed/trezorhal/common.c

@@ -4,8 +4,9 @@
 #include "display.h"
 #include "rng.h"
 
+void shutdown(void);
+
 void __attribute__((noreturn)) __fatal_error(const char *expr, const char *msg, const char *file, int line, const char *func) {
-    for (volatile uint32_t delay = 0; delay < 10000000; delay++) {}
     display_orientation(0);
     display_backlight(255);
     display_print_color(COLOR_WHITE, COLOR_RED128);
@@ -27,6 +28,7 @@ void __attribute__((noreturn)) __fatal_error(const char *expr, const char *msg,
 #define STR(s) #s
     display_printf("rev : %s\n", XSTR(GITREV));
 #endif
+    shutdown();
     for (;;);
 }
 

embed/trezorhal/util.s

@@ -62,4 +62,33 @@ jump_to:
   ldr r12, =0
   bx r0
 
+  .global shutdown
+  .type shutdown, STT_FUNC
+shutdown:
+  cpsid f
+  ldr r0, =ccmram_start
+  ldr r1, =ccmram_end
+  ldr r2, =0
+  bl memset_reg
+  ldr r0, =sram_start
+  ldr r1, =sram_end
+  ldr r2, =0
+  bl memset_reg
+  ldr lr, =0xffffffff
+  ldr r0, =0
+  ldr r1, =0
+  ldr r2, =0
+  ldr r3, =0
+  ldr r4, =0
+  ldr r5, =0
+  ldr r6, =0
+  ldr r7, =0
+  ldr r8, =0
+  ldr r9, =0
+  ldr r10, =0
+  ldr r11, =0
+  ldr r12, =0
+
+  b . // loop forever
+
   .end