nissa/nereid: implement board_set_active_charge_port

This change makes the Nereid charger actually be enabled when the charger
task requests it, allowing the battery to charge.

BUG=b:201000844
TEST=battery now charges at ~4400 mA when charging from port C0 with PD
     contract for 3A at 20V, stops charging with `chgoverride -2`
BRANCH=none

Signed-off-by: Peter Marheine <pmarheine@chromium.org>
Change-Id: If22f10954c71a2d2f7f5007eeb115770a9723a02
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3449990
Reviewed-by: Andrew McRae <amcrae@google.com>

1 files changed, 50 insertions, 1 deletions

diff --git a/zephyr/projects/nissa/src/nereid/usbc.c b/zephyr/projects/nissa/src/nereid/usbc.c
index e6d514dd8f..7cd42b4d73 100644
--- a/zephyr/projects/nissa/src/nereid/usbc.c
+++ b/zephyr/projects/nissa/src/nereid/usbc.c
@@ -82,7 +82,56 @@ __override bool pd_check_vbus_level(int port, enum vbus_level level)
 
 int board_set_active_charge_port(int port)
 {
-	return EC_SUCCESS;
+	int is_real_port = (port >= 0 && port < board_get_usb_pd_port_count());
+	int i;
+	int old_port;
+	int rv;
+
+	if (!is_real_port && port != CHARGE_PORT_NONE)
+		return EC_ERROR_INVAL;
+
+	old_port = charge_manager_get_active_charge_port();
+	LOG_INF("Charge update: p%d -> p%d", old_port, port);
+
+	/* Check if port is sourcing VBUS. */
+	if (port != CHARGE_PORT_NONE && charger_is_sourcing_otg_power(port)) {
+		LOG_WRN("Skip enable p%d: already sourcing", port);
+		return EC_ERROR_INVAL;
+	}
+
+	/* Disable sinking on all ports except the desired one */
+	for (i = 0; i < board_get_usb_pd_port_count(); i++) {
+		if (i == port)
+			continue;
+
+		if (sm5803_vbus_sink_enable(i, 0))
+			/*
+			 * Do not early-return because this can fail during
+			 * power-on which would put us into a loop.
+			 */
+			LOG_WRN("p%d: sink path disable failed.", i);
+	}
+
+	/* Don't enable anything (stop here) if no ports were requested */
+	if (port == CHARGE_PORT_NONE)
+		return EC_SUCCESS;
+
+	/*
+	 * Stop the charger IC from switching while changing ports.  Otherwise,
+	 * we can overcurrent the adapter we're switching to. (crbug.com/926056)
+	 */
+	if (old_port != CHARGE_PORT_NONE)
+		charger_discharge_on_ac(1);
+
+	/* Enable requested charge port. */
+	rv = sm5803_vbus_sink_enable(port, 1);
+	if (rv)
+		LOG_WRN("p%d: sink path enable failed: code %d", port, rv);
+
+	/* Allow the charger IC to begin/continue switching. */
+	charger_discharge_on_ac(0);
+
+	return rv;
 }
 
 uint16_t tcpc_get_alert_status(void)