233 lines
6.3 KiB
C
233 lines
6.3 KiB
C
/*
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* Battery driver for LEGO MINDSTORMS EV3
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*
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* Copyright (C) 2017 David Lechner <david@lechnology.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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* This program is distributed "as is" WITHOUT ANY WARRANTY of any
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* kind, whether express or implied; without even the implied warranty
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* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/delay.h>
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#include <linux/err.h>
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#include <linux/gpio/consumer.h>
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#include <linux/iio/consumer.h>
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#include <linux/iio/types.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of_device.h>
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#include <linux/platform_device.h>
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#include <linux/power_supply.h>
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struct lego_ev3_battery {
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struct iio_channel *iio_v;
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struct iio_channel *iio_i;
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struct gpio_desc *rechargeable_gpio;
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struct power_supply *psy;
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int technology;
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int v_max;
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int v_min;
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};
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static int lego_ev3_battery_get_property(struct power_supply *psy,
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enum power_supply_property psp,
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union power_supply_propval *val)
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{
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struct lego_ev3_battery *batt = power_supply_get_drvdata(psy);
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int ret, val2;
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switch (psp) {
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case POWER_SUPPLY_PROP_TECHNOLOGY:
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val->intval = batt->technology;
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break;
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case POWER_SUPPLY_PROP_VOLTAGE_NOW:
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/* battery voltage is iio channel * 2 + Vce of transistor */
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ret = iio_read_channel_processed(batt->iio_v, &val->intval);
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if (ret)
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return ret;
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val->intval *= 2000;
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val->intval += 50000;
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/* plus adjust for shunt resistor drop */
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ret = iio_read_channel_processed(batt->iio_i, &val2);
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if (ret)
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return ret;
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val2 *= 1000;
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val2 /= 15;
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val->intval += val2;
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break;
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case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
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val->intval = batt->v_max;
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break;
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case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
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val->intval = batt->v_min;
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break;
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case POWER_SUPPLY_PROP_CURRENT_NOW:
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/* battery current is iio channel / 15 / 0.05 ohms */
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ret = iio_read_channel_processed(batt->iio_i, &val->intval);
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if (ret)
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return ret;
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val->intval *= 20000;
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val->intval /= 15;
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break;
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case POWER_SUPPLY_PROP_SCOPE:
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val->intval = POWER_SUPPLY_SCOPE_SYSTEM;
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break;
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default:
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return -EINVAL;
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}
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return 0;
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}
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static int lego_ev3_battery_set_property(struct power_supply *psy,
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enum power_supply_property psp,
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const union power_supply_propval *val)
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{
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struct lego_ev3_battery *batt = power_supply_get_drvdata(psy);
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switch (psp) {
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case POWER_SUPPLY_PROP_TECHNOLOGY:
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/*
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* Only allow changing technology from Unknown to NiMH. Li-ion
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* batteries are automatically detected and should not be
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* overridden. Rechargeable AA batteries, on the other hand,
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* cannot be automatically detected, and so must be manually
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* specified. This should only be set once during system init,
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* so there is no mechanism to go back to Unknown.
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*/
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if (batt->technology != POWER_SUPPLY_TECHNOLOGY_UNKNOWN)
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return -EINVAL;
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switch (val->intval) {
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case POWER_SUPPLY_TECHNOLOGY_NiMH:
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batt->technology = POWER_SUPPLY_TECHNOLOGY_NiMH;
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batt->v_max = 7800000;
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batt->v_min = 5400000;
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break;
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default:
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return -EINVAL;
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}
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break;
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default:
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return -EINVAL;
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}
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return 0;
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}
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static int lego_ev3_battery_property_is_writeable(struct power_supply *psy,
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enum power_supply_property psp)
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{
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struct lego_ev3_battery *batt = power_supply_get_drvdata(psy);
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return psp == POWER_SUPPLY_PROP_TECHNOLOGY &&
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batt->technology == POWER_SUPPLY_TECHNOLOGY_UNKNOWN;
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}
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static enum power_supply_property lego_ev3_battery_props[] = {
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POWER_SUPPLY_PROP_TECHNOLOGY,
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POWER_SUPPLY_PROP_VOLTAGE_NOW,
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POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
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POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN,
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POWER_SUPPLY_PROP_CURRENT_NOW,
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POWER_SUPPLY_PROP_SCOPE,
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};
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static const struct power_supply_desc lego_ev3_battery_desc = {
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.name = "lego-ev3-battery",
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.type = POWER_SUPPLY_TYPE_BATTERY,
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.properties = lego_ev3_battery_props,
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.num_properties = ARRAY_SIZE(lego_ev3_battery_props),
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.get_property = lego_ev3_battery_get_property,
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.set_property = lego_ev3_battery_set_property,
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.property_is_writeable = lego_ev3_battery_property_is_writeable,
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};
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static int lego_ev3_battery_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct lego_ev3_battery *batt;
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struct power_supply_config psy_cfg = {};
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int err;
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batt = devm_kzalloc(dev, sizeof(*batt), GFP_KERNEL);
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if (!batt)
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return -ENOMEM;
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platform_set_drvdata(pdev, batt);
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batt->iio_v = devm_iio_channel_get(dev, "voltage");
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err = PTR_ERR_OR_ZERO(batt->iio_v);
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if (err)
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return dev_err_probe(dev, err,
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"Failed to get voltage iio channel\n");
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batt->iio_i = devm_iio_channel_get(dev, "current");
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err = PTR_ERR_OR_ZERO(batt->iio_i);
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if (err)
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return dev_err_probe(dev, err,
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"Failed to get current iio channel\n");
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batt->rechargeable_gpio = devm_gpiod_get(dev, "rechargeable", GPIOD_IN);
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err = PTR_ERR_OR_ZERO(batt->rechargeable_gpio);
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if (err)
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return dev_err_probe(dev, err,
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"Failed to get rechargeable gpio\n");
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/*
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* The rechargeable battery indication switch cannot be changed without
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* removing the battery, so we only need to read it once.
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*/
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if (gpiod_get_value(batt->rechargeable_gpio)) {
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/* 2-cell Li-ion, 7.4V nominal */
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batt->technology = POWER_SUPPLY_TECHNOLOGY_LION;
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batt->v_max = 84000000;
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batt->v_min = 60000000;
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} else {
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/* 6x AA Alkaline, 9V nominal */
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batt->technology = POWER_SUPPLY_TECHNOLOGY_UNKNOWN;
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batt->v_max = 90000000;
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batt->v_min = 48000000;
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}
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psy_cfg.of_node = pdev->dev.of_node;
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psy_cfg.drv_data = batt;
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batt->psy = devm_power_supply_register(dev, &lego_ev3_battery_desc,
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&psy_cfg);
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err = PTR_ERR_OR_ZERO(batt->psy);
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if (err) {
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dev_err(dev, "failed to register power supply\n");
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return err;
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}
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return 0;
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}
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static const struct of_device_id of_lego_ev3_battery_match[] = {
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{ .compatible = "lego,ev3-battery", },
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{ }
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};
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MODULE_DEVICE_TABLE(of, of_lego_ev3_battery_match);
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static struct platform_driver lego_ev3_battery_driver = {
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.driver = {
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.name = "lego-ev3-battery",
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.of_match_table = of_lego_ev3_battery_match,
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},
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.probe = lego_ev3_battery_probe,
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};
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module_platform_driver(lego_ev3_battery_driver);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("David Lechner <david@lechnology.com>");
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MODULE_DESCRIPTION("LEGO MINDSTORMS EV3 Battery Driver");
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