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References: <20181122101119.29194-1-enric.balletbo@collabora.com> <20181122101119.29194-2-enric.balletbo@collabora.com>
In-Reply-To: <20181122101119.29194-2-enric.balletbo@collabora.com>
From:   Guenter Roeck <groeck@google.com>
Date:   Thu, 22 Nov 2018 07:24:29 -0800
Message-ID: <CABXOdTemckwTZx-q=VYfNYSeXKbY_YQ3wEYZtDvGYKt-U6KXYg@mail.gmail.com>
Subject: Re: [PATCH v2 2/2] power: supply: cros: allow to set input voltage
 and current limit.
To:     Enric Balletbo i Serra <enric.balletbo@collabora.com>
Cc:     linux-pm@vger.kernel.org, Sebastian Reichel <sre@kernel.org>,
        Sameer Nanda <snanda@chromium.org>,
        Gwendal Grignou <gwendal@chromium.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Guenter Roeck <groeck@chromium.org>,
        Adam.Thomson.Opensource@diasemi.com, kernel@collabora.com,
        Benson Leung <bleung@chromium.org>
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Sender: linux-kernel-owner@vger.kernel.org
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On Thu, Nov 22, 2018 at 2:11 AM Enric Balletbo i Serra
<enric.balletbo@collabora.com> wrote:
>
> 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 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;
> --
> 2.19.1
>