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232 lines
6.3 KiB
232 lines
6.3 KiB
/* |
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* Battery driver for LEGO MINDSTORMS EV3 |
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* |
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* Copyright (C) 2017 David Lechner <[email protected]> |
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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 <[email protected]>"); |
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MODULE_DESCRIPTION("LEGO MINDSTORMS EV3 Battery Driver");
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