sm5803: Add sm5803_is_acok()

This commit adds a function to return whether the voltage before the
switching FETs is greater than ~4V.  This would generally be the
criteria for other buck-boost chargers which have an "ACOK" signal.

BUG=b:187965740
BRANCH=dedede
TEST=With other changes, build and flash drawcia, verify that "AC on"
prints are only printed when we decide to charge from a port and not
just when VBUS is present

Signed-off-by: Aseda Aboagye <aaboagye@google.com>
Change-Id: If3a5398197fb0a251b5290d107daf88e56ca12b4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2901253
Tested-by: Aseda Aboagye <aaboagye@chromium.org>
Reviewed-by: Diana Z <dzigterman@chromium.org>
Commit-Queue: Aseda Aboagye <aaboagye@chromium.org>

2 files changed, 66 insertions, 4 deletions

diff --git a/driver/charger/sm5803.c b/driver/charger/sm5803.c
index 81108e7506..d4a20826a7 100644
--- a/driver/charger/sm5803.c
+++ b/driver/charger/sm5803.c
@@ -9,6 +9,7 @@
 #include "battery_smart.h"
 #include "charge_state_v2.h"
 #include "charger.h"
+#include "extpower.h"
 #include "gpio.h"
 #include "hooks.h"
 #include "i2c.h"
@@ -624,6 +625,12 @@ static void sm5803_init(int chgnum)
 	rv = chg_write8(chgnum, SM5803_REG_DPM_VL_SET_MSB, (reg >> 3));
 	rv |= chg_write8(chgnum, SM5803_REG_DPM_VL_SET_LSB, (reg & 0x7));
 
+	/* Set the VCHGPWR thresholds to mirror those for VBUS. */
+	rv |= meas_write8(chgnum, SM5803_REG_VCHG_PWR_HIGH_TH,
+			  SM5803_VBUS_HIGH_LEVEL);
+	rv |= meas_write8(chgnum, SM5803_REG_VCHG_PWR_LOW_TH,
+			  SM5803_VBUS_LOW_LEVEL);
+
 	/* Set default input current */
 	reg = SM5803_CURRENT_TO_REG(CONFIG_CHARGER_INPUT_CURRENT)
 		& SM5803_CHG_ILIM_RAW;
@@ -647,8 +654,11 @@ static void sm5803_init(int chgnum)
 						SM5803_TINT_MIN_LEVEL);
 
 
-	/* Configure TINT interrupts to fire after thresholds are set */
-	rv |= main_write8(chgnum, SM5803_REG_INT2_EN, SM5803_INT2_TINT);
+	/*
+	 * Configure TINT & VCHGPWR interrupts to fire after thresholds are set
+	 */
+	rv |= main_write8(chgnum, SM5803_REG_INT2_EN, SM5803_INT2_TINT |
+						      SM5803_INT2_VCHGPWR);
 
 	/*
 	 * Configure CHG_ENABLE to only be set through I2C by setting
@@ -1020,12 +1030,10 @@ void sm5803_handle_interrupt(int chgnum)
 			charger_vbus[chgnum] = 0;
 			if (IS_ENABLED(CONFIG_USB_CHARGER))
 				usb_charger_vbus_change(chgnum, 0);
-			board_vbus_present_change();
 		} else {
 			charger_vbus[chgnum] = 1;
 			if (IS_ENABLED(CONFIG_USB_CHARGER))
 				usb_charger_vbus_change(chgnum, 1);
-			board_vbus_present_change();
 		}
 	}
 
@@ -1070,6 +1078,10 @@ void sm5803_handle_interrupt(int chgnum)
 		 */
 	}
 
+	/* Update extpower if VCHGPWR changes. */
+	if (int_reg & SM5803_INT2_VCHGPWR)
+		board_vbus_present_change();
+
 	/* TODO(b/159376384): Take action on fatal BFET power alert. */
 	rv = main_read8(chgnum, SM5803_REG_INT3_REQ, &int_reg);
 	if (rv) {
@@ -1474,6 +1486,40 @@ static enum ec_error_list sm5803_get_option(int chgnum, int *option)
 	return rv;
 }
 
+enum ec_error_list sm5803_is_acok(int chgnum, bool *acok)
+{
+	int rv;
+	enum sm5803_charger_modes mode;
+	int reg;
+
+	rv = chg_read8(chgnum, SM5803_REG_FLOW1, &reg);
+	if (rv)
+		return rv;
+
+	/* The charger mode is contained in the last 2 bits. */
+	reg &= SM5803_FLOW1_MODE;
+	mode = (enum sm5803_charger_modes)reg;
+
+	/* If we're not sinking, then AC can't be OK. */
+	if (mode != CHARGER_MODE_SINK) {
+		*acok = false;
+		return EC_SUCCESS;
+	}
+
+	/*
+	 * Okay, we're sinking.  Check that VCHGPWR has some voltage.  This
+	 * should indicate that the path is good.
+	 */
+	rv = meas_read8(chgnum, SM5803_REG_VCHG_PWR_MSB, &reg);
+	if (rv)
+		return rv;
+
+	/* Assume that ACOK would be asserted if VCHGPWR is higher than ~4V. */
+	*acok = reg >= SM5803_VBUS_HIGH_LEVEL;
+
+	return EC_SUCCESS;
+}
+
 static enum ec_error_list sm5803_is_input_current_limit_reached(int chgnum,
 								bool *reached)
 {
diff --git a/driver/charger/sm5803.h b/driver/charger/sm5803.h
index 79dbd55129..e1a3e10560 100644
--- a/driver/charger/sm5803.h
+++ b/driver/charger/sm5803.h
@@ -8,6 +8,8 @@
 #ifndef __CROS_EC_SM5803_H
 #define __CROS_EC_SM5803_H
 
+#include "common.h"
+
 /* Note: configure charger struct with CHARGER_FLAGS */
 #define SM5803_ADDR_MAIN_FLAGS		0x30
 #define SM5803_ADDR_MEAS_FLAGS		0x31
@@ -132,6 +134,8 @@ enum sm5803_gpio0_modes {
 /* Note: Threshold registers all assume lower 2 bits are 0 */
 #define SM5803_REG_VBUS_LOW_TH		0x1A
 #define SM5803_REG_VBUS_HIGH_TH		0x2A
+#define SM5803_REG_VCHG_PWR_LOW_TH	0x1B
+#define SM5803_REG_VCHG_PWR_HIGH_TH	0x2B
 #define SM5803_REG_TINT_LOW_TH		0x1D
 #define SM5803_REG_TINT_HIGH_TH		0x2D
 
@@ -172,6 +176,9 @@ enum sm5803_gpio0_modes {
 #define SM5803_VBUS_MEAS_OV_TEMP	BIT(5)
 #define SM5803_VBUS_MEAS_CHG_DET	BIT(6)
 
+/* VCHGPWR levels - The VCHGPWR levels increment in 23.4mV steps. */
+#define SM5803_REG_VCHG_PWR_MSB		0x4A
+
 #define SM5803_REG_TINT_MEAS_MSB	0x4E
 
 /* VSYS levels - The VSYS levels increment in  23.4mV steps. */
@@ -382,6 +389,15 @@ enum ec_error_list sm5803_vbus_sink_enable(int chgnum, int enable);
 void sm5803_hibernate(int chgnum);
 void sm5803_interrupt(int chgnum);
 
+/**
+ * Return whether ACOK is high or low.
+ *
+ * @param chgnum index into chg_chips table.
+ * @param acok will be set to true if ACOK is asserted, otherwise false.
+ * @return EC_SUCCESS, error otherwise.
+ */
+enum ec_error_list sm5803_is_acok(int chgnum, bool *acok);
+
 /* Expose low power mode functions */
 void sm5803_disable_low_power_mode(int chgnum);
 void sm5803_enable_low_power_mode(int chgnum);