Change in simtrace2[master]: make peer ERASE more robust

[Kévin Redon]

Kévin Redon has uploaded this change for review. ( https://gerrit.osmocom.org/14144


Change subject: make peer ERASE more robust
......................................................................

make peer ERASE more robust

adds command 'a' to allow setting/asserting the peer SAM3S ERASE
line on the next command.
this prevents against accidental erase since only the command 'y'
was required, without confirmation.
this could happen not only through accidental user input, but
noise on the serial line (noise would still cause other issues,
but at least now it will not "brick" the device).
now the sequence 'ay' is required, as any other command following
'a' would clear the permission again.

note: since ERASE is only setting a GPIO within this command
parsing function, not accidental function pointer problem calling
'board_exec_dbg_cmd' should cause accidental ERASE since it would
need to be called two times with the exact sequence

Change-Id: I06bfeaef09a397bd554bec84321e0dd64ccc3aac
---
M firmware/libboard/qmod/source/board_qmod.c
1 file changed, 22 insertions(+), 3 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/simtrace2 refs/changes/44/14144/1

diff --git a/firmware/libboard/qmod/source/board_qmod.c b/firmware/libboard/qmod/source/board_qmod.c
index ad1f6b7..cab5271 100644
--- a/firmware/libboard/qmod/source/board_qmod.c
+++ b/firmware/libboard/qmod/source/board_qmod.c
@@ -1,7 +1,7 @@
 /* sysmocom quad-modem sysmoQMOD application code
  *
  * (C) 2016-2017 by Harald Welte <hwelte at hmw-consulting.de>
- * (C) 2018, sysmocom -s.f.m.c. GmbH, Author: Kevin Redon <kredon at sysmocom.de>
+ * (C) 2018-2019, sysmocom -s.f.m.c. GmbH, Author: Kevin Redon <kredon at sysmocom.de>
  *
  * 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
@@ -184,6 +184,11 @@
 /* returns '1' in case we should break any endless loop */
 void board_exec_dbg_cmd(int ch)
 {
+	/* this variable controls if it is allowed to assert/release the ERASE line.
+	   this is done to prevent accidental ERASE on noisy serial input since only one character can trigger the ERASE.
+	 */
+	static bool allow_erase = false;
+
 	switch (ch) {
 	case '?':
 		printf("\t?\thelp\n\r");
@@ -205,6 +210,7 @@
 		printf("\tX\tRelease peer SAM3 from reset\n\r");
 		printf("\tx\tAssert peer SAM3 reset\n\r");
 		printf("\tY\tRelease peer SAM3 ERASE signal\n\r");
+		printf("\ta\tAllow asserting peer SAM3 ERASE signal\n\r");
 		printf("\ty\tAssert peer SAM3 ERASE signal\n\r");
 		printf("\tU\tProceed to USB Initialization\n\r");
 		printf("\t1\tGenerate 1ms reset pulse on WWAN1\n\r");
@@ -243,9 +249,17 @@
 		printf("Clearing SIMTRACExx_ERASE (inactive)\n\r");
 		PIO_Clear(&pin_peer_erase);
 		break;
+	case 'a':
+		printf("Asserting SIMTRACExx_ERASE allowed on next command\n\r");
+		allow_erase = true;
+		break;
 	case 'y':
-		printf("Seetting SIMTRACExx_ERASE (active)\n\r");
-		PIO_Set(&pin_peer_erase);
+		if (allow_erase) {
+			printf("Setting SIMTRACExx_ERASE (active)\n\r");
+			PIO_Set(&pin_peer_erase);
+		} else {
+			printf("Please first allow setting SIMTRACExx_ERASE\n\r");
+		}
 		break;
 	case '1':
 		printf("Resetting Modem 1 (of this SAM3)\n\r");
@@ -268,6 +282,11 @@
 			board_exec_dbg_cmd_st12only(ch);
 		break;
 	}
+
+	// set protection back so it can only run for one command
+	if ('a' != ch) {
+		allow_erase = false;
+	}
 }
 
 void board_main_top(void)

-- 
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Gerrit-Project: simtrace2
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I06bfeaef09a397bd554bec84321e0dd64ccc3aac
Gerrit-Change-Number: 14144
Gerrit-PatchSet: 1
Gerrit-Owner: Kévin Redon <kredon at sysmocom.de>
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