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Subject[RESEND PATCH v3 2/2] power: supply: cros: allow to set input voltage and current limit
Date
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>
---

Changes in v3: None
Changes in v2:
- Fix the upper limit that can be set.
- Remove unnecessary else.

drivers/power/supply/cros_usbpd-charger.c | 116 ++++++++++++++++++++++
1 file changed, 116 insertions(+)

diff --git a/drivers/power/supply/cros_usbpd-charger.c b/drivers/power/supply/cros_usbpd-charger.c
index 7e9c3984ef6a..3a9ea94c3de3 100644
--- 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;
--
2.20.1
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