pd: don't enable try.src when battery is not present or too low

Don't enable try.src when battery is not present or <1% because
try.src will temporarily cut off power to system.

BUG=chrome-os-partner:43413
BRANCH=samus
TEST=tested on samus using "battfake" ec command. when battery
<1%, verified that try.src is disabled and when battery >=1% and
the AP is on (dual-role toggling is on), then try.src is enabled.
verified boot without battery succeeds on samus and glados.

Change-Id: I64816bb7c9669bfeca61687bcd9a48da32e67945
Signed-off-by: Alec Berg <alecaberg@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/289854
Reviewed-by: Scott Collyer <scollyer@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

3 files changed, 48 insertions, 17 deletions

diff --git a/board/samus_pd/board.c b/board/samus_pd/board.c
index dcf40cdd99..e1941cabbe 100644
--- a/board/samus_pd/board.c
+++ b/board/samus_pd/board.c
@@ -624,8 +624,11 @@ void board_set_charge_limit(int charge_ma)
 
 static void board_update_battery_soc(int soc)
 {
-	batt_soc = soc;
-	board_update_charge_limit(desired_charge_rate_ma);
+	if (batt_soc != soc) {
+		batt_soc = soc;
+		board_update_charge_limit(desired_charge_rate_ma);
+		hook_notify(HOOK_BATTERY_SOC_CHANGE);
+	}
 }
 
 /* Send host event up to AP */
diff --git a/common/usb_pd_protocol.c b/common/usb_pd_protocol.c
index 24f8b63e86..1ab2209d5d 100644
--- a/common/usb_pd_protocol.c
+++ b/common/usb_pd_protocol.c
@@ -7,6 +7,7 @@
 #include "board.h"
 #include "case_closed_debug.h"
 #include "charge_manager.h"
+#include "charge_state.h"
 #include "chipset.h"
 #include "common.h"
 #include "console.h"
@@ -1167,21 +1168,43 @@ enum pd_dual_role_states pd_get_dual_role(void)
 	return drp_state;
 }
 
+#ifdef CONFIG_USB_PD_TRY_SRC
+static void pd_update_try_source(void)
+{
+	int i;
+
+#ifndef CONFIG_CHARGER
+	int batt_soc = board_get_battery_soc();
+#else
+	int batt_soc = charge_get_percent();
+#endif
+
+	/*
+	 * Enable try source when dual-role toggling AND battery is present
+	 * and at some minimum percentage.
+	 */
+	pd_try_src_enable = drp_state == PD_DRP_TOGGLE_ON &&
+			    batt_soc >= CONFIG_USB_PD_TRY_SRC_MIN_BATT_SOC;
+
+	/*
+	 * Clear this flag to cover case where a TrySrc
+	 * mode went from enabled to disabled and trying_source
+	 * was active at that time.
+	 */
+	for (i = 0; i < CONFIG_USB_PD_PORT_COUNT; i++)
+		pd[i].flags &= ~PD_FLAGS_TRY_SRC;
+
+}
+DECLARE_HOOK(HOOK_BATTERY_SOC_CHANGE, pd_update_try_source, HOOK_PRIO_DEFAULT);
+#endif
+
 void pd_set_dual_role(enum pd_dual_role_states state)
 {
 	int i;
 	drp_state = state;
 
 #ifdef CONFIG_USB_PD_TRY_SRC
-	pd_try_src_enable = (state == PD_DRP_TOGGLE_ON) ? 1 : 0;
-	for (i = 0; i < CONFIG_USB_PD_PORT_COUNT; i++) {
-		/*
-		 * Clear this flag to cover case where a TrySrc
-		 * mode went from enabled to disabled and trying_source
-		 * was active at that time.
-		 */
-		pd[i].flags &= ~PD_FLAGS_TRY_SRC;
-	}
+	pd_update_try_source();
 #endif
 
 	for (i = 0; i < CONFIG_USB_PD_PORT_COUNT; i++) {
@@ -2770,14 +2793,16 @@ static int command_pd(int argc, char **argv)
 	else if (!strncasecmp(argv[1], "trysrc", 6)) {
 		int enable;
 
-		if (argc < 3)
+		if (argc < 2) {
 			return EC_ERROR_PARAM_COUNT;
+		} else if (argc >= 3) {
+			enable = strtoi(argv[2], &e, 10);
+			if (*e)
+				return EC_ERROR_PARAM3;
+			pd_try_src_enable = enable ? 1 : 0;
+		}
 
-		enable = strtoi(argv[2], &e, 10);
-		if (*e)
-			return EC_ERROR_PARAM3;
-		pd_try_src_enable = enable ? 1 : 0;
-		ccprintf("Try.SRC %s\n", enable ? "on" : "off");
+		ccprintf("Try.SRC %s\n", pd_try_src_enable ? "on" : "off");
 		return EC_SUCCESS;
 	}
 #endif
diff --git a/include/config.h b/include/config.h
index 293d86eb7c..2b1152468d 100644
--- a/include/config.h
+++ b/include/config.h
@@ -1616,6 +1616,9 @@
 /* Use this option to enable Try.SRC mode for Dual Role devices */
 #undef CONFIG_USB_PD_TRY_SRC
 
+/* Set the default minimum battery percentage for Try.Src to be enabled */
+#define CONFIG_USB_PD_TRY_SRC_MIN_BATT_SOC 1
+
 /* Alternative configuration keeping only the TX part of PHY */
 #undef CONFIG_USB_PD_TX_PHY_ONLY