osiris: Discharge on AC when high MLCC noise

Charger will work on the hybrid mode if battery full and system
current over 3A. The voltage gap between the Vsys and Vbat will
cause the Vsys has high ripple, Although it is normal design
behaviors, But it will cause MLCC noise a bit larger than other
conditions.

This CL force battery discharge when battery full, So the battery
MOS of NVDC charger will turn on always, it make the Vsys same
as Vbat and the noise has been improved.

BUG=b:246214501
TEST=check battery discharging when battery full
BRANCH=none

Signed-off-by: Yu-An Chen <yu-an.chen@quanta.corp-partner.google.com>
Change-Id: I61c65efbe4d44697371f3e039c8193e0adc9ec6c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3890025
Reviewed-by: Boris Mittelberg <bmbm@google.com>
Commit-Queue: YH Lin <yueherngl@chromium.org>

2 files changed, 72 insertions, 0 deletions

diff --git a/board/osiris/battery.c b/board/osiris/battery.c
index 9664c4279b..72bbf00819 100644
--- a/board/osiris/battery.c
+++ b/board/osiris/battery.c
@@ -7,6 +7,9 @@
 
 #include "battery_fuel_gauge.h"
 #include "cbi.h"
+#include "charge_ramp.h"
+#include "charge_state.h"
+#include "charger_profile_override.h"
 #include "common.h"
 #include "compile_time_macros.h"
 #include "gpio.h"
@@ -74,3 +77,69 @@ enum battery_present battery_hw_present(void)
 	/* The GPIO is low when the battery is physically present */
 	return gpio_get_level(GPIO_EC_BATT_PRES_ODL) ? BP_NO : BP_YES;
 }
+
+static int charger_should_discharge_on_ac(struct charge_state_data *curr)
+{
+	/* can not discharge on AC without battery */
+	if (curr->batt.is_present != BP_YES)
+		return 0;
+
+	/* Do not discharge on AC if the battery is still waking up */
+	if ((curr->batt.flags & BATT_FLAG_BAD_STATUS) ||
+	    (!(curr->batt.flags & BATT_FLAG_WANT_CHARGE) &&
+	     !(curr->batt.status & STATUS_FULLY_CHARGED)))
+		return 0;
+
+	/*
+	 * In heavy load (>3A being withdrawn from VSYS) the DCDC of the
+	 * charger operates on hybrid mode. This causes a slight voltage
+	 * ripple on VSYS that falls in the audible noise frequency (single
+	 * digit kHz range). This small ripple generates audible noise in
+	 * the output ceramic capacitors (caps on VSYS and any input of
+	 * DCDC under VSYS).
+	 *
+	 * To overcome this issue, force battery discharging when battery
+	 * full, So the battery MOS of NVDC charger will turn on always,
+	 * it make the Vsys same as Vbat and the noise has been improved.
+	 */
+	if (!battery_is_cut_off() &&
+	    !(curr->batt.flags & BATT_FLAG_WANT_CHARGE) &&
+	    (curr->batt.status & STATUS_FULLY_CHARGED))
+		return 1;
+
+	return 0;
+}
+
+/*
+ * This can override the smart battery's charging profile. To make a change,
+ * modify one or more of requested_voltage, requested_current, or state.
+ * Leave everything else unchanged.
+ *
+ * Return the next poll period in usec, or zero to use the default (which is
+ * state dependent).
+ */
+int charger_profile_override(struct charge_state_data *curr)
+{
+	int disch_on_ac = charger_should_discharge_on_ac(curr);
+
+	charger_discharge_on_ac(disch_on_ac);
+
+	if (disch_on_ac) {
+		curr->state = ST_DISCHARGE;
+		return 0;
+	}
+
+	return 0;
+}
+
+enum ec_status charger_profile_override_get_param(uint32_t param,
+						  uint32_t *value)
+{
+	return EC_RES_INVALID_PARAM;
+}
+
+enum ec_status charger_profile_override_set_param(uint32_t param,
+						  uint32_t value)
+{
+	return EC_RES_INVALID_PARAM;
+}
diff --git a/board/osiris/board.h b/board/osiris/board.h
index b1eaf3a5c2..c35cdce314 100644
--- a/board/osiris/board.h
+++ b/board/osiris/board.h
@@ -65,6 +65,9 @@
 #define PD_MAX_CURRENT_MA 3000
 #define PD_MAX_VOLTAGE_MV 20000
 
+#define CONFIG_CHARGER_PROFILE_OVERRIDE
+#define CONFIG_PWR_STATE_DISCHARGE_FULL
+
 /*
  * Macros for GPIO signals used in common code that don't match the
  * schematic names. Signal names in gpio.inc match the schematic and are