power: supply: cros: allow to set input voltage and current limit

This patch allows reading and writing the input voltage and current
limit through the POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT and
POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT sysfs properties. This allows
userspace to see current values and to re-configure these values at
runtime based on system-level knowledge or user input.

By default there is no limit, this is reported as a -1 when reading from
userspace. Writing a value will set the current or voltage limit in uA
or uV, and writing any negative value will remove that limit.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

diff --git a/drivers/power/supply/cros_usbpd-charger.c b/drivers/power/supply/cros_usbpd-charger.c
index 7e9c398..3a9ea94 100644 (file)
--- a/drivers/power/supply/cros_usbpd-charger.c
+++ b/drivers/power/supply/cros_usbpd-charger.c
@@ -53,6 +53,8 @@ struct charger_data {
 };
 
 static enum power_supply_property cros_usbpd_charger_props[] = {
+       POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
+       POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT,
        POWER_SUPPLY_PROP_ONLINE,
        POWER_SUPPLY_PROP_STATUS,
        POWER_SUPPLY_PROP_CURRENT_MAX,
@@ -80,6 +82,10 @@ static enum power_supply_usb_type cros_usbpd_charger_usb_types[] = {
        POWER_SUPPLY_USB_TYPE_APPLE_BRICK_ID
 };
 
+/* Input voltage/current limit in mV/mA. Default to none. */
+static u16 input_voltage_limit = EC_POWER_LIMIT_NONE;
+static u16 input_current_limit = EC_POWER_LIMIT_NONE;
+
 static bool cros_usbpd_charger_port_is_dedicated(struct port_data *port)
 {
        return port->port_number >= port->charger->num_usbpd_ports;
@@ -324,6 +330,26 @@ static int cros_usbpd_charger_get_port_status(struct port_data *port,
        return ret;
 }
 
+static int cros_usbpd_charger_set_ext_power_limit(struct charger_data *charger,
+                                                 u16 current_lim,
+                                                 u16 voltage_lim)
+{
+       struct ec_params_external_power_limit_v1 req;
+       int ret;
+
+       req.current_lim = current_lim;
+       req.voltage_lim = voltage_lim;
+
+       ret = cros_usbpd_charger_ec_command(charger, 0,
+                                           EC_CMD_EXTERNAL_POWER_LIMIT,
+                                           &req, sizeof(req), NULL, 0);
+       if (ret < 0)
+               dev_err(charger->dev,
+                       "Unable to set the 'External Power Limit': %d\n", ret);
+
+       return ret;
+}
+
 static void cros_usbpd_charger_power_changed(struct power_supply *psy)
 {
        struct port_data *port = power_supply_get_drvdata(psy);
@@ -396,6 +422,18 @@ static int cros_usbpd_charger_get_prop(struct power_supply *psy,
        case POWER_SUPPLY_PROP_USB_TYPE:
                val->intval = port->psy_usb_type;
                break;
+       case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+               if (input_current_limit == EC_POWER_LIMIT_NONE)
+                       val->intval = -1;
+               else
+                       val->intval = input_current_limit * 1000;
+               break;
+       case POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT:
+               if (input_voltage_limit == EC_POWER_LIMIT_NONE)
+                       val->intval = -1;
+               else
+                       val->intval = input_voltage_limit * 1000;
+               break;
        case POWER_SUPPLY_PROP_MODEL_NAME:
                val->strval = port->model_name;
                break;
@@ -409,6 +447,81 @@ static int cros_usbpd_charger_get_prop(struct power_supply *psy,
        return 0;
 }
 
+static int cros_usbpd_charger_set_prop(struct power_supply *psy,
+                                      enum power_supply_property psp,
+                                      const union power_supply_propval *val)
+{
+       struct port_data *port = power_supply_get_drvdata(psy);
+       struct charger_data *charger = port->charger;
+       struct device *dev = charger->dev;
+       u16 intval;
+       int ret;
+
+       /* U16_MAX in mV/mA is the maximum supported value */
+       if (val->intval >= U16_MAX * 1000)
+               return -EINVAL;
+       /* A negative number is used to clear the limit */
+       if (val->intval < 0)
+               intval = EC_POWER_LIMIT_NONE;
+       else    /* Convert from uA/uV to mA/mV */
+               intval = val->intval / 1000;
+
+       switch (psp) {
+       case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+               ret = cros_usbpd_charger_set_ext_power_limit(charger, intval,
+                                                       input_voltage_limit);
+               if (ret < 0)
+                       break;
+
+               input_current_limit = intval;
+               if (input_current_limit == EC_POWER_LIMIT_NONE)
+                       dev_info(dev,
+                         "External Current Limit cleared for all ports\n");
+               else
+                       dev_info(dev,
+                         "External Current Limit set to %dmA for all ports\n",
+                         input_current_limit);
+               break;
+       case POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT:
+               ret = cros_usbpd_charger_set_ext_power_limit(charger,
+                                                       input_current_limit,
+                                                       intval);
+               if (ret < 0)
+                       break;
+
+               input_voltage_limit = intval;
+               if (input_voltage_limit == EC_POWER_LIMIT_NONE)
+                       dev_info(dev,
+                         "External Voltage Limit cleared for all ports\n");
+               else
+                       dev_info(dev,
+                         "External Voltage Limit set to %dmV for all ports\n",
+                         input_voltage_limit);
+               break;
+       default:
+               ret = -EINVAL;
+       }
+
+       return ret;
+}
+
+static int cros_usbpd_charger_property_is_writeable(struct power_supply *psy,
+                                               enum power_supply_property psp)
+{
+       int ret;
+
+       switch (psp) {
+       case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+       case POWER_SUPPLY_PROP_INPUT_VOLTAGE_LIMIT:
+               ret = 1;
+               break;
+       default:
+               ret = 0;
+       }
+
+       return ret;
+}
+
 static int cros_usbpd_charger_ec_event(struct notifier_block *nb,
                                       unsigned long queued_during_suspend,
                                       void *_notify)
@@ -525,6 +638,9 @@ static int cros_usbpd_charger_probe(struct platform_device *pd)
 
                psy_desc = &port->psy_desc;
                psy_desc->get_property = cros_usbpd_charger_get_prop;
+               psy_desc->set_property = cros_usbpd_charger_set_prop;
+               psy_desc->property_is_writeable =
+                               cros_usbpd_charger_property_is_writeable;
                psy_desc->external_power_changed =
                                        cros_usbpd_charger_power_changed;
                psy_cfg.drv_data = port;