[PATCH 2/2] usb: typec: ucsi: psy: Fix voltage and current max for non-Fixed PDOs

[Benson Leung <bleung@chromium.org>]

ucsi_psy_get_voltage_max and ucsi_psy_get_current_max are calculated
using whichever pdo is in the last position of the src_pdos array, presuming
it to be a fixed pdo, so the pdo_fixed_voltage or pdo_max_current
helpers are used on that last pdo.

However, non-Fixed PDOs such as Battery PDOs, Augmented PDOs (used for AVS and
for PPS) may exist, and are always at the end of the array if they do.
In the event one of these more advanced chargers are attached the helpers for
fixed return mangled values.

Here's an example case of a Google Pixel Flex Dual Port 67W USB-C Fast Charger
with PPS support:
POWER_SUPPLY_NAME=ucsi-source-psy-cros_ec_ucsi.4.auto2
POWER_SUPPLY_TYPE=USB
POWER_SUPPLY_CHARGE_TYPE=Standard
POWER_SUPPLY_USB_TYPE=C [PD] PD_PPS PD_DRP
POWER_SUPPLY_ONLINE=1
POWER_SUPPLY_VOLTAGE_MIN=5000000
POWER_SUPPLY_VOLTAGE_MAX=13400000
POWER_SUPPLY_VOLTAGE_NOW=20000000
POWER_SUPPLY_CURRENT_MAX=5790000
POWER_SUPPLY_CURRENT_NOW=3250000

Voltage Max is reading as 13.4V, but that's an incorrect decode of the PPS
APDO in the last position. Same goes for CURRENT_MAX. 5.79A is incorrect.

Instead, enumerate through the src_pdos and filter just for Fixed PDOs for
now, and find the one with the highest voltage and current respectively.

After, from the same charger:
POWER_SUPPLY_NAME=ucsi-source-psy-cros_ec_ucsi.4.auto2
POWER_SUPPLY_TYPE=USB
POWER_SUPPLY_CHARGE_TYPE=Standard
POWER_SUPPLY_USB_TYPE=C [PD] PD_PPS PD_DRP
POWER_SUPPLY_ONLINE=1
POWER_SUPPLY_VOLTAGE_MIN=5000000
POWER_SUPPLY_VOLTAGE_MAX=20000000
POWER_SUPPLY_VOLTAGE_NOW=20000000
POWER_SUPPLY_CURRENT_MAX=4000000
POWER_SUPPLY_CURRENT_NOW=3250000

Signed-off-by: Benson Leung <bleung@chromium.org>
---
 drivers/usb/typec/ucsi/psy.c | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/typec/ucsi/psy.c b/drivers/usb/typec/ucsi/psy.c
index b828719e33df..c8ebab8ba7e7 100644
--- a/drivers/usb/typec/ucsi/psy.c
+++ b/drivers/usb/typec/ucsi/psy.c
@@ -112,15 +112,20 @@ static int ucsi_psy_get_voltage_max(struct ucsi_connector *con,
 				    union power_supply_propval *val)
 {
 	u32 pdo;
+	int max_voltage = 0;
 
 	switch (UCSI_CONSTAT(con, PWR_OPMODE)) {
 	case UCSI_CONSTAT_PWR_OPMODE_PD:
-		if (con->num_pdos > 0) {
-			pdo = con->src_pdos[con->num_pdos - 1];
-			val->intval = pdo_fixed_voltage(pdo) * 1000;
-		} else {
-			val->intval = 0;
+		for (int i = 0; i < con->num_pdos; i++) {
+			int pdo_voltage = 0;
+
+			pdo = con->src_pdos[i];
+			if (pdo_type(pdo) == PDO_TYPE_FIXED)
+				pdo_voltage = pdo_fixed_voltage(pdo) * 1000;
+			max_voltage = (pdo_voltage > max_voltage) ? pdo_voltage
+								  : max_voltage;
 		}
+		val->intval = max_voltage;
 		break;
 	case UCSI_CONSTAT_PWR_OPMODE_TYPEC3_0:
 	case UCSI_CONSTAT_PWR_OPMODE_TYPEC1_5:
@@ -168,6 +173,7 @@ static int ucsi_psy_get_current_max(struct ucsi_connector *con,
 				    union power_supply_propval *val)
 {
 	u32 pdo;
+	int max_current = 0;
 
 	if (!UCSI_CONSTAT(con, CONNECTED)) {
 		val->intval = 0;
@@ -176,12 +182,16 @@ static int ucsi_psy_get_current_max(struct ucsi_connector *con,
 
 	switch (UCSI_CONSTAT(con, PWR_OPMODE)) {
 	case UCSI_CONSTAT_PWR_OPMODE_PD:
-		if (con->num_pdos > 0) {
-			pdo = con->src_pdos[con->num_pdos - 1];
-			val->intval = pdo_max_current(pdo) * 1000;
-		} else {
-			val->intval = 0;
+		for (int i = 0; i < con->num_pdos; i++) {
+			int pdo_current = 0;
+
+			pdo = con->src_pdos[i];
+			if (pdo_type(pdo) == PDO_TYPE_FIXED)
+				pdo_current = pdo_max_current(pdo) * 1000;
+			max_current = (pdo_current > max_current) ? pdo_current
+								  : max_current;
 		}
+		val->intval = max_current;
 		break;
 	case UCSI_CONSTAT_PWR_OPMODE_TYPEC1_5:
 		val->intval = UCSI_TYPEC_1_5_CURRENT * 1000;
-- 
2.52.0.223.gf5cc29aaa4-goog