port80: Track and export last post code in previous boot

- Add a special port80 event for LPC reset assertion and use that event
to store the previous post code.
- Add a new command to retrive the last saved post code so I can easily
query it at boot/resume and log unusual codes.

BUG=none
TEST=manual (with additional coreboot/mosys changes)

- interrupt boot process by issuing x86reset on EC console or
by using warm reset button on servo
- read event log with mosys on next boot

78 | 2012-08-13 09:24:04 | System boot | 262
79 | 2012-08-13 09:24:04 | Last post code in previous boot | 0x9e
80 | 2012-08-13 09:24:04 | System Reset

Change-Id: I7b9f10442b9c468d89fde4e75adb94b0c07c2c8d
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/29995
Reviewed-by: Randall Spangler <rspangler@chromium.org>

4 files changed, 46 insertions, 2 deletions

diff --git a/chip/lm4/lpc.c b/chip/lm4/lpc.c
index 8477dbc3d7..41da2ab8b8 100644
--- a/chip/lm4/lpc.c
+++ b/chip/lm4/lpc.c
@@ -558,6 +558,10 @@ static void lpc_interrupt(void)
 
 	/* Debugging: print changes to LPC0RESET */
 	if (mis & (1 << 31)) {
+		/* Store port 80 event so we know where reset happened */
+		if (LM4_LPC_LPCSTS & (1 << 10))
+			port_80_write(PORT_80_EVENT_RESET);
+
 		CPRINTF("[%T LPC RESET# %sasserted]\n",
 			(LM4_LPC_LPCSTS & (1<<10)) ? "" : "de");
 	}
diff --git a/common/port80.c b/common/port80.c
index f8a6c8395d..72b8ccde11 100644
--- a/common/port80.c
+++ b/common/port80.c
@@ -7,6 +7,7 @@
 
 #include "board.h"
 #include "console.h"
+#include "host_command.h"
 #include "port80.h"
 #include "util.h"
 
@@ -16,6 +17,7 @@
 
 static uint16_t history[HISTORY_LEN];
 static int writes;  /* Number of port 80 writes so far */
+static int last_boot; /* Last code from previous boot */
 static int scroll;
 static int print_in_int = 1;
 
@@ -30,6 +32,15 @@ void port_80_write(int data)
 	if (print_in_int)
 		CPRINTF("%c[%T Port 80: 0x%02x]", scroll ? '\n' : '\r', data);
 
+	/* Save current port80 code if system is resetting */
+	if (data == PORT_80_EVENT_RESET && writes) {
+		int prev = history[(writes-1) % ARRAY_SIZE(history)];
+
+		/* Ignore special event codes */
+		if (prev < 0x100)
+			last_boot = prev;
+	}
+
 	history[writes % ARRAY_SIZE(history)] = data;
 	writes++;
 }
@@ -82,10 +93,16 @@ static int command_port80(int argc, char **argv)
 	ccputs("Port 80 writes:");
 	for (i = tail; i < head; i++) {
 		int e = history[i % ARRAY_SIZE(history)];
-		if (e == PORT_80_EVENT_RESUME) {
+		switch (e) {
+		case PORT_80_EVENT_RESUME:
 			ccprintf("\n(S3->S0)");
 			printed = 0;
-		} else {
+			break;
+		case PORT_80_EVENT_RESET:
+			ccprintf("\n(RESET)");
+			printed = 0;
+			break;
+		default:
 			if (!(printed++ % 20)) {
 				ccputs("\n ");
 				cflush();
@@ -100,3 +117,15 @@ DECLARE_CONSOLE_COMMAND(port80, command_port80,
 			"[scroll | intprint | flush]",
 			"Print port80 writes or toggle port80 scrolling",
 			NULL);
+
+int port80_last_boot(struct host_cmd_handler_args *args)
+{
+	struct ec_response_port80_last_boot *r = args->response;
+
+	args->response_size = sizeof(*r);
+	r->code = last_boot;
+
+	return EC_RES_SUCCESS;
+}
+DECLARE_HOST_COMMAND(EC_CMD_PORT80_LAST_BOOT,
+		     port80_last_boot, EC_VER_MASK(0));
diff --git a/include/ec_commands.h b/include/ec_commands.h
index bda5995d55..c1b19bcf1a 100644
--- a/include/ec_commands.h
+++ b/include/ec_commands.h
@@ -736,6 +736,16 @@ struct ec_response_rtc {
 #define EC_CMD_RTC_SET_ALARM 0x47
 
 /*****************************************************************************/
+/* Port80 log access */
+
+/* Get last port80 code from previous boot */
+#define EC_CMD_PORT80_LAST_BOOT 0x48
+
+struct ec_response_port80_last_boot {
+	uint16_t code;
+} __packed;
+
+/*****************************************************************************/
 /* Thermal engine commands */
 
 /* Set thershold value */
diff --git a/include/port80.h b/include/port80.h
index 0d251d1d1f..28966750c6 100644
--- a/include/port80.h
+++ b/include/port80.h
@@ -12,6 +12,7 @@
 
 enum port_80_event {
 	PORT_80_EVENT_RESUME = 0x1001,  /* S3->S0 transition */
+	PORT_80_EVENT_RESET = 0x1002,   /* RESET transition */
 };
 
 /**