gaia: Add a warm reboot function

Added a warm reboot function that reboots the AP while preserving
RAM contents. This will be helpful in debugging AP/OS hard hangs since
in conjunction with PSTORE_CONSOLE in the kernel, the kernel log messages
from the previous boot will be preserved.

BUG=chrome-os-partner:13249
TEST=1. From EC console issue the "warm_reboot" command. Upon rebooting
"cat /dev/pstore/console-ramoops" and ensure that the contents are dmesg
of previous boot.
2. Reboot the system using alt-volume_up-r key combination. Upon
rebooting, check pstore contents in the same manner as case#1 above.
BRANCH=snow

Change-Id: Ic8f0415da6182f4c1bc2d35b91302ceda5c19569
Signed-off-by: Sameer Nanda <snanda@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/31523
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

3 files changed, 55 insertions, 0 deletions

diff --git a/chip/stm32/keyboard_scan.c b/chip/stm32/keyboard_scan.c
index 350439ef1e..de537cc931 100644
--- a/chip/stm32/keyboard_scan.c
+++ b/chip/stm32/keyboard_scan.c
@@ -64,6 +64,16 @@ static const uint8_t actual_key_masks[4][KB_OUTPUTS] = {
 #define MASK_INDEX_REFRESH 2
 #define MASK_VALUE_REFRESH 0x04
 
+/* Key masks and values for warm reboot combination */
+#define MASK_INDEX_KEYR		3
+#define MASK_VALUE_KEYR		0x80
+#define MASK_INDEX_VOL_UP	4
+#define MASK_VALUE_VOL_UP	0x01
+#define MASK_INDEX_RIGHT_ALT	10
+#define MASK_VALUE_RIGHT_ALT	0x01
+#define MASK_INDEX_LEFT_ALT	10
+#define MASK_VALUE_LEFT_ALT	0x40
+
 struct kbc_gpio {
 	int num;		/* logical row or column number */
 	uint32_t port;
@@ -217,6 +227,16 @@ void enter_polling_mode(void)
 	select_column(COL_TRI_STATE_ALL);
 }
 
+static int check_warm_reboot_keys(void)
+{
+	if (raw_state[MASK_INDEX_KEYR] == MASK_VALUE_KEYR &&
+		  raw_state[MASK_INDEX_VOL_UP] == MASK_VALUE_VOL_UP &&
+		  (raw_state[MASK_INDEX_RIGHT_ALT] == MASK_VALUE_RIGHT_ALT ||
+		  raw_state[MASK_INDEX_LEFT_ALT] == MASK_VALUE_LEFT_ALT))
+		return 1;
+
+	return 0;
+}
 
 /* Returns 1 if any key is still pressed. 0 if no key is pressed. */
 static int check_keys_changed(void)
@@ -295,6 +315,11 @@ static int check_keys_changed(void)
 		}
 		CPUTS("]\n");
 
+		if (num_press == 3) {
+			if (check_warm_reboot_keys())
+				system_warm_reboot();
+		}
+
 		if (kb_fifo_add(raw_state) == EC_SUCCESS)
 			board_interrupt_host(1);
 		else
diff --git a/common/gaia_power.c b/common/gaia_power.c
index 2ef6f3ddf5..a3de5b91df 100644
--- a/common/gaia_power.c
+++ b/common/gaia_power.c
@@ -588,3 +588,30 @@ DECLARE_CONSOLE_COMMAND(power, command_power,
 			"on/off",
 			"Turn AP power on/off",
 			NULL);
+
+void system_warm_reboot(void)
+{
+	CPRINTF("[%T EC triggered warm reboot ]\n");
+
+	/* This is a hack to do an AP warm reboot while still preserving
+	 * RAM contents. This is useful for looking at kernel log message
+	 * contents from previous boot in cases where the AP/OS is hard
+	 * hung. */
+	gpio_set_level(GPIO_EN_PP5000, 0);
+	gpio_set_level(GPIO_EN_PP3300, 0);
+
+	power_request = POWER_REQ_ON;
+	task_wake(TASK_ID_GAIAPOWER);
+
+	return;
+}
+
+static int command_warm_reboot(int argc, char **argv)
+{
+	system_warm_reboot();
+	return EC_SUCCESS;
+}
+DECLARE_CONSOLE_COMMAND(warm_reboot, command_warm_reboot,
+			NULL,
+			"EC triggered warm reboot",
+			NULL);
diff --git a/include/system.h b/include/system.h
index c11e89814d..f3d5b035d6 100644
--- a/include/system.h
+++ b/include/system.h
@@ -156,6 +156,9 @@ const char *system_get_build_info(void);
 
 void system_reset(int flags);
 
+/* System warm reboot while keeping the RAM alive. */
+void system_warm_reboot(void);
+
 /* Set a scratchpad register to the specified value.  The scratchpad
  * register must maintain its contents across a software-requested
  * warm reset. */