From ccb45ff8a2285fbee6d87c02789dc7b00250dc82 Mon Sep 17 00:00:00 2001
From: Alec Berg <alecaberg@chromium.org>
Date: Mon, 18 Aug 2014 16:25:12 -0700
Subject: [PATCH] samus: enabled fast charging for EVT ATL cells

Enable fast charging with profile designed for ATL cells
that will be used in EVT.

BUG=chrome-os-partner:23776
BRANCH=none
TEST=Took detailed charging/discharging data and verified
that the actual profile matches the desired profile and that
the fast charging profile is actually faster than the
standard. See bug report for more info and data collected.

Change-Id: Ic11ab89e48afb73987b8013abf8b0564e1138156
Signed-off-by: Alec Berg <alecaberg@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/212980
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
---
 driver/battery/samus.c | 70 ++++++++++++++++++++++++++++++------------
 1 file changed, 51 insertions(+), 19 deletions(-)

diff --git a/driver/battery/samus.c b/driver/battery/samus.c
index 951130867e..6458af0199 100644
--- a/driver/battery/samus.c
+++ b/driver/battery/samus.c
@@ -46,7 +46,7 @@ const struct battery_info *battery_get_info(void)
 
 #ifdef CONFIG_CHARGER_PROFILE_OVERRIDE
 
-static int fast_charging_allowed;
+static int fast_charging_allowed = 1;
 
 /*
  * This can override the smart battery's charging profile. To make a change,
@@ -58,6 +58,15 @@ static int fast_charging_allowed;
  */
 int charger_profile_override(struct charge_state_data *curr)
 {
+	/* temp in 0.1 deg C */
+	int temp_c = curr->batt.temperature - 2731;
+	/* keep track of last temperature range for hysteresis */
+	static enum {
+		TEMP_LOW,
+		TEMP_NORMAL,
+		TEMP_HIGH
+	} temp_range = TEMP_NORMAL;
+
 	/* We only want to override how we charge, nothing else. */
 	if (curr->state != ST_CHARGE)
 		return 0;
@@ -66,25 +75,48 @@ int charger_profile_override(struct charge_state_data *curr)
 	if (!fast_charging_allowed)
 		return 0;
 
-	/* Okay, impose our custom will */
-	curr->requested_current = 9000;
-	curr->requested_voltage = 8300;
-	if (curr->batt.current <= 6300) {
-		curr->requested_current = 6300;
-		curr->requested_voltage = 8400;
-	} else if (curr->batt.current <= 4500) {
-		curr->requested_current = 4500;
-		curr->requested_voltage = 8500;
-	} else if (curr->batt.current <= 2700) {
-		curr->requested_current = 2700;
+	/*
+	 * Okay, impose our custom will:
+	 * When battery is 15-45C:
+	 * CC at 9515mA @ 8.3V
+	 * CV at 8.3V until current drops to 4759mA
+	 * CC at 4759mA @ 8.7V
+	 * CV at 8.7V
+	 *
+	 * When battery is <15C:
+	 * CC at 2854mA @ 8.7V
+	 * CV at 8.7V
+	 *
+	 * When battery is >45C:
+	 * CC at 6660mA @ 8.3V
+	 * CV at 8.3V (when battery is hot we don't go to fully charged)
+	 *
+	 * Add 0.2 degrees of hysteresis.
+	 */
+	if (temp_c < 149)
+		temp_range = TEMP_LOW;
+	else if (temp_c > 151 && temp_c < 449)
+		temp_range = TEMP_NORMAL;
+	else if (temp_c > 451)
+		temp_range = TEMP_HIGH;
+
+	switch (temp_range) {
+	case TEMP_LOW:
+		curr->requested_current = 2854;
 		curr->requested_voltage = 8700;
-	} else if (curr->batt.current <= 475) {
-		/*
-		 * Should we stop? If so, how do we start again?
-		 * For now, just use the battery's profile.
-		 */
-		curr->requested_current = curr->batt.desired_current;
-		curr->requested_voltage = curr->batt.desired_voltage;
+		break;
+	case TEMP_NORMAL:
+		curr->requested_current = 9515;
+		curr->requested_voltage = 8300;
+		if (curr->batt.current <= 4759 && curr->batt.voltage >= 8250) {
+			curr->requested_current = 4759;
+			curr->requested_voltage = 8700;
+		}
+		break;
+	case TEMP_HIGH:
+		curr->requested_current = 6660;
+		curr->requested_voltage = 8300;
+		break;
 	}
 
 	return 0;