chgstv2: Sustain battery SoC

This patch makes chgstv2 capable of sustaining the battery soc
(a.k.a. sustain soc).

The sustain soc is off on reset. It's enabled or disabled by the host
using EC_CMD_CHARGE_CONTROL. For example, the host can disable it
on every resume and re-enable it on every suspend.

BUG=b:188457962
BRANCH=None
TEST=atlas

Change-Id: I62b4e8bc9517900a5a32d2f35369c645fa8a60c3
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>

Author: dnojiri

common/charge_state_v2.c

@@ -91,6 +91,7 @@ static int manual_current;  /* Manual current override (-1 = no override) */
 static unsigned int user_current_limit = -1U;
 test_export_static timestamp_t shutdown_target_time;
 static timestamp_t precharge_start_time;
+static struct sustain_soc sustain_soc;
 
 /*
  * The timestamp when the battery charging current becomes stable.
@@ -1155,6 +1156,8 @@ static void dump_charge_state(void)
 		 battery_seems_to_be_disconnected);
 	ccprintf("battery_was_removed = %d\n", battery_was_removed);
 	ccprintf("debug output = %s\n", debugging ? "on" : "off");
+	ccprintf("sustain charge = %d%% ~ %d%%\n",
+		 sustain_soc.lower, sustain_soc.upper);
 #undef DUMP
 }
 
@@ -1630,6 +1633,43 @@ static int battery_outside_charging_temperature(void)
 }
 #endif
 
+static void sustain_soc_disable(void)
+{
+	sustain_soc.lower = -1;
+	sustain_soc.upper = -1;
+}
+
+static int sustain_soc_set(int16_t lower, int16_t upper)
+{
+	if (sustain_soc.lower < sustain_soc.upper
+			&& 0 <= sustain_soc.lower && sustain_soc.upper <= 100) {
+		sustain_soc.lower = lower;
+		sustain_soc.upper = upper;
+		return EC_SUCCESS;
+	}
+
+	CPRINTS("Invalid param: %s(%d, %d)", __func__, lower, upper);
+	return EC_ERROR_INVAL;
+}
+
+static bool sustain_soc_enabled(void)
+{
+	return sustain_soc.lower != -1 && sustain_soc.upper != -1;
+}
+
+static void sustain_battery_soc(void)
+{
+	/* If both of AC and battery aren't present, nothing to do. */
+	if (!curr.ac || curr.batt.is_present != BP_YES
+			|| !sustain_soc_enabled())
+		return;
+
+	if (curr.batt.state_of_charge < sustain_soc.lower)
+		set_chg_ctrl_mode(CHARGE_CONTROL_NORMAL);
+	else if (sustain_soc.upper < curr.batt.state_of_charge)
+		set_chg_ctrl_mode(CHARGE_CONTROL_DISCHARGE);
+}
+
 /*****************************************************************************/
 /* Hooks */
 void charger_init(void)
@@ -1645,6 +1685,8 @@ void charger_init(void)
 	 * their tasks. Make them ready first.
 	 */
 	battery_get_params(&curr.batt);
+
+	sustain_soc_disable();
 }
 DECLARE_HOOK(HOOK_INIT, charger_init, HOOK_PRIO_DEFAULT);
 
@@ -2061,6 +2103,7 @@ void charger_task(void *u)
 		    (is_full != prev_full) ||
 		    (curr.state != prev_state) ||
 		    (curr.batt.display_charge != prev_disp_charge)) {
+			sustain_battery_soc();
 			show_charging_progress();
 			prev_charge = curr.batt.state_of_charge;
 			prev_disp_charge = curr.batt.display_charge;
@@ -2621,6 +2664,22 @@ charge_command_charge_control(struct host_cmd_handler_args *args)
 	if (rv != EC_SUCCESS)
 		return EC_RES_ERROR;
 
+	if (args->version >= 2) {
+		/*
+		 * If charge mode is explicitly set (e.g. DISCHARGE), make sure
+		 * sustain charge is disabled. To go back to normal mode (and
+		 * disable sustain charge), set mode=NORMAL, lower=-1, upper=-1.
+		 */
+		if (chg_ctl_mode == CHARGE_CONTROL_NORMAL) {
+			rv = sustain_soc_set(p->sustain_charge.lower,
+						p->sustain_charge.upper);
+			if (rv)
+				return EC_RES_INVALID_PARAM;
+		} else {
+			sustain_soc_disable();
+		}
+	}
+
 #ifdef CONFIG_CHARGER_DISCHARGE_ON_AC
 #ifdef CONFIG_CHARGER_DISCHARGE_ON_AC_CUSTOM
 	rv = board_discharge_on_ac(p->mode == CHARGE_CONTROL_DISCHARGE);
@@ -2824,6 +2883,7 @@ static int command_chgstate(int argc, char **argv)
 {
 	int rv;
 	int val;
+	char *e;
 
 	if (argc > 1) {
 		if (!strcasecmp(argv[1], "idle")) {
@@ -2858,6 +2918,20 @@ static int command_chgstate(int argc, char **argv)
 				return EC_ERROR_PARAM_COUNT;
 			if (!parse_bool(argv[2], &debugging))
 				return EC_ERROR_PARAM2;
+		} else if (!strcasecmp(argv[1], "sustain")) {
+			int lower, upper;
+
+			if (argc <= 3)
+				return EC_ERROR_PARAM_COUNT;
+			lower = strtoi(argv[2], &e, 0);
+			if (*e)
+				return EC_ERROR_PARAM2;
+			upper = strtoi(argv[3], &e, 0);
+			if (*e)
+				return EC_ERROR_PARAM3;
+			rv = sustain_soc_set(lower, upper);
+			if (rv)
+				return EC_ERROR_INVAL;
 		} else {
 			return EC_ERROR_PARAM1;
 		}
@@ -2867,7 +2941,8 @@ static int command_chgstate(int argc, char **argv)
 	return EC_SUCCESS;
 }
 DECLARE_CONSOLE_COMMAND(chgstate, command_chgstate,
-			"[idle|discharge|debug on|off]",
+			"[idle|discharge|debug on|off]"
+			"\n[sustain lower upper]",
 			"Get/set charge state machine status");
 
 #ifdef CONFIG_EC_EC_COMM_BATTERY_MASTER

include/charge_state_v2.h

@@ -51,6 +51,11 @@ struct charge_state_data {
 #endif
 };
 
+struct sustain_soc {
+	int16_t lower;
+	int16_t upper;
+};
+
 /**
  * Set the output current limit and voltage. This is used to provide power from
  * the charger chip ("OTG" mode).

include/ec_commands.h

@@ -4177,6 +4177,11 @@ enum ec_charge_control_mode {
 
 struct ec_params_charge_control {
 	uint32_t mode;  /* enum charge_control_mode */
+	/* For sustain charge (v2). The struct doesn't need to be exported. */
+	struct {
+		int16_t lower;
+		int16_t upper;
+	} sustain_charge;
 } __ec_align4;
 
 /*****************************************************************************/