The bq2425x devices support charging with a configurable charge current
i_chg or a specific fixed low-current in what's called Low Charge mode.
This patch exposes access to the Low Charge mode through a POWER_
SUPPLY_PROP_CHARGE_TYPE sysfs property value of POWER_SUPPLY_CHARGE_
TYPE_TRICKLE. It also allows to completely disable charging if desired
by setting the property to POWER_SUPPLY_CHARGE_TYPE_NONE. Normal
charging with the configured i_chg current is activated through
POWER_SUPPLY_CHARGE_TYPE_FAST (default).

Signed-off-by: Andreas Dannenberg <dannenb...@ti.com>
---
 drivers/power/bq24257_charger.c | 90 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)

diff --git a/drivers/power/bq24257_charger.c b/drivers/power/bq24257_charger.c
index f0d4307..886040c 100644
--- a/drivers/power/bq24257_charger.c
+++ b/drivers/power/bq24257_charger.c
@@ -265,6 +265,56 @@ enum bq24257_fault {
        FAULT_INPUT_LDO_LOW,
 };
 
+static int bq24257_get_charge_type(struct bq24257_device *bq,
+               union power_supply_propval *val)
+{
+       int ret;
+
+       ret = bq24257_field_read(bq, F_CE);
+       if (ret < 0)
+               return ret;
+
+       /* Charge Enable is active-low */
+       if (ret) {
+               val->intval = POWER_SUPPLY_CHARGE_TYPE_NONE;
+               return 0;
+       }
+
+       /* Low Charge means a fixed low-current is used instead of i_chg */
+       ret = bq24257_field_read(bq, F_LOW_CHG);
+       if (ret < 0)
+               return ret;
+
+       val->intval = ret ? POWER_SUPPLY_CHARGE_TYPE_TRICKLE :
+                       POWER_SUPPLY_CHARGE_TYPE_FAST;
+
+       return 0;
+}
+
+static int bq24257_set_charge_type(struct bq24257_device *bq,
+               const union power_supply_propval *val)
+{
+       int ret;
+
+       switch (val->intval) {
+       case POWER_SUPPLY_CHARGE_TYPE_NONE:
+               return bq24257_field_write(bq, F_CE, 1);
+       case POWER_SUPPLY_CHARGE_TYPE_TRICKLE:
+               ret = bq24257_field_write(bq, F_LOW_CHG, 1);
+               break;
+       case POWER_SUPPLY_CHARGE_TYPE_FAST:
+               ret = bq24257_field_write(bq, F_LOW_CHG, 0);
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       if (ret < 0)
+               return ret;
+
+       return bq24257_field_write(bq, F_CE, 0);
+}
+
 static int bq24257_power_supply_get_property(struct power_supply *psy,
                                             enum power_supply_property psp,
                                             union power_supply_propval *val)
@@ -290,6 +340,10 @@ static int bq24257_power_supply_get_property(struct 
power_supply *psy,
                        val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
                break;
 
+       case POWER_SUPPLY_PROP_CHARGE_TYPE:
+               ret = bq24257_get_charge_type(bq, val);
+               break;
+
        case POWER_SUPPLY_PROP_MANUFACTURER:
                val->strval = BQ24257_MANUFACTURER;
                break;
@@ -358,6 +412,39 @@ static int bq24257_power_supply_get_property(struct 
power_supply *psy,
        return ret;
 }
 
+static int bq24257_power_supply_set_property(struct power_supply *psy,
+               enum power_supply_property prop,
+               const union power_supply_propval *val)
+{
+       struct bq24257_device *bq = power_supply_get_drvdata(psy);
+       int ret;
+
+       mutex_lock(&bq->lock);
+
+       switch (prop) {
+       case POWER_SUPPLY_PROP_CHARGE_TYPE:
+               ret = bq24257_set_charge_type(bq, val);
+               break;
+       default:
+               ret = -EINVAL;
+       }
+
+       mutex_unlock(&bq->lock);
+
+       return ret;
+}
+
+static int bq24257_power_supply_property_is_writeable(struct power_supply *psy,
+               enum power_supply_property psp)
+{
+       switch (psp) {
+       case POWER_SUPPLY_PROP_CHARGE_TYPE:
+               return true;
+       default:
+               return false;
+       }
+}
+
 static int bq24257_get_chip_state(struct bq24257_device *bq,
                                  struct bq24257_state *state)
 {
@@ -683,6 +770,7 @@ static enum power_supply_property 
bq24257_power_supply_props[] = {
        POWER_SUPPLY_PROP_MANUFACTURER,
        POWER_SUPPLY_PROP_MODEL_NAME,
        POWER_SUPPLY_PROP_STATUS,
+       POWER_SUPPLY_PROP_CHARGE_TYPE,
        POWER_SUPPLY_PROP_ONLINE,
        POWER_SUPPLY_PROP_HEALTH,
        POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT,
@@ -702,6 +790,8 @@ static const struct power_supply_desc 
bq24257_power_supply_desc = {
        .properties = bq24257_power_supply_props,
        .num_properties = ARRAY_SIZE(bq24257_power_supply_props),
        .get_property = bq24257_power_supply_get_property,
+       .set_property = bq24257_power_supply_set_property,
+       .property_is_writeable  = bq24257_power_supply_property_is_writeable
 };
 
 static ssize_t bq24257_show_ovp_voltage(struct device *dev,
-- 
1.9.1

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