samus: Kick battery out of disconnect state when AC is attached

The Samus battery can be placed into a disconnect state by asserting a
disconnect input signal. In this state, the battery will not function
until a charging current is applied. This patch adds detection of the
disconnect state. If a battery in disconnect state is found, a current
is force-applied to the battery to kick it out of disconnect.

BRANCH=None
TEST=Manual on Samus.
1. Put battery into disconnect state
2. Pull AC, then reattach AC
3. Verify "found battery in disconnect state" is seen on the
EC console.
4. Pull AC and verify that EC console is still accessable
Also verify that battery gets out of reset state:
1. Pull AC
2. Issue "i2cxfer w16 0 0x16 0x0 0x12" command on EC console
3. Re-attach AC
4. Pull AC and verify that EC console is still accessable
BUG=chrome-os-partner:29465

Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Change-Id: Ib4268887fb483094ac4e641749200268160d3014
Reviewed-on: https://chromium-review.googlesource.com/209013
Reviewed-by: Alec Berg <alecaberg@chromium.org>
Commit-Queue: Alec Berg <alecaberg@chromium.org>
Tested-by: Alec Berg <alecaberg@chromium.org>

1 files changed, 62 insertions, 0 deletions

diff --git a/driver/battery/samus.c b/driver/battery/samus.c
index de361b2d59..4c4f3480c4 100644
--- a/driver/battery/samus.c
+++ b/driver/battery/samus.c
@@ -5,9 +5,11 @@
  * Battery pack vendor provided charging profile
  */
 
+#include "battery_smart.h"
 #include "charge_state.h"
 #include "console.h"
 #include "ec_commands.h"
+#include "extpower.h"
 #include "util.h"
 
 static const struct battery_info info = {
@@ -152,3 +154,63 @@ DECLARE_CONSOLE_COMMAND(fastcharge, command_fastcharge,
 			NULL);
 
 #endif	/* CONFIG_CHARGER_PROFILE_OVERRIDE */
+
+#ifdef CONFIG_BATTERY_REVIVE_DISCONNECT
+/*
+ * Check if battery is in disconnect state, a state entered by pulling
+ * BATT_DISCONN_N low, and clear that state if we have external power plugged
+ * and no battery faults are detected. Disconnect state resembles battery
+ * shutdown mode, but extra steps must be taken to get the battery out of this
+ * mode.
+ */
+enum battery_disconnect_state battery_get_disconnect_state(void)
+{
+	uint8_t data[6];
+	int rv;
+	/*
+	 * Take note if we find that the battery isn't in disconnect state,
+	 * and always return NOT_DISCONNECTED without probing the battery.
+	 * This assumes the battery will not go to disconnect state during
+	 * runtime.
+	 */
+	static int not_disconnected;
+
+	if (not_disconnected)
+		return BATTERY_NOT_DISCONNECTED;
+
+	if (extpower_is_present()) {
+		/* Check if battery charging + discharging is disabled. */
+		rv = sb_write(SB_MANUFACTURER_ACCESS, PARAM_OPERATION_STATUS);
+		if (rv)
+			return BATTERY_DISCONNECT_ERROR;
+
+		rv = sb_read_string(I2C_PORT_BATTERY, BATTERY_ADDR,
+				    SB_ALT_MANUFACTURER_ACCESS, data, 6);
+
+		if (rv || !(data[3] & BATTERY_DISCHARGING_DISABLED) ||
+		    !(data[3] & BATTERY_CHARGING_DISABLED)) {
+			not_disconnected = 1;
+			return BATTERY_NOT_DISCONNECTED;
+		}
+
+		/*
+		 * Battery is neither charging nor discharging. Verify that
+		 * we didn't enter this state due to a safety fault.
+		 */
+		rv = sb_write(SB_MANUFACTURER_ACCESS, PARAM_SAFETY_STATUS);
+		if (rv)
+			return BATTERY_DISCONNECT_ERROR;
+
+		rv = sb_read_string(I2C_PORT_BATTERY, BATTERY_ADDR,
+				    SB_ALT_MANUFACTURER_ACCESS, data, 6);
+
+		if (rv || data[2] || data[3] || data[4] || data[5])
+			return BATTERY_DISCONNECT_ERROR;
+		else
+			/* No safety fault -- clear disconnect state. */
+			return BATTERY_DISCONNECTED;
+	}
+	not_disconnected = 1;
+	return BATTERY_NOT_DISCONNECTED;
+}
+#endif /* CONFIG_BATTERY_REVIVE_DISCONNECT */