diff options
Diffstat (limited to 'drivers/power/supply/lego_ev3_battery.c')
| -rw-r--r-- | drivers/power/supply/lego_ev3_battery.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/drivers/power/supply/lego_ev3_battery.c b/drivers/power/supply/lego_ev3_battery.c new file mode 100644 index 0000000..7b993d6 --- /dev/null +++ b/drivers/power/supply/lego_ev3_battery.c @@ -0,0 +1,228 @@ +/* + * Battery driver for LEGO MINDSTORMS EV3 + * + * Copyright (C) 2017 David Lechner <david@lechnology.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + + * This program is distributed "as is" WITHOUT ANY WARRANTY of any + * kind, whether express or implied; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/gpio/consumer.h> +#include <linux/iio/consumer.h> +#include <linux/iio/types.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/power_supply.h> + +struct lego_ev3_battery { + struct iio_channel *iio_v; + struct iio_channel *iio_i; + struct gpio_desc *rechargeable_gpio; + struct power_supply *psy; + int technology; + int v_max; + int v_min; +}; + +static int lego_ev3_battery_get_property(struct power_supply *psy, + enum power_supply_property psp, + union power_supply_propval *val) +{ + struct lego_ev3_battery *batt = power_supply_get_drvdata(psy); + int val2; + + switch (psp) { + case POWER_SUPPLY_PROP_TECHNOLOGY: + val->intval = batt->technology; + break; + case POWER_SUPPLY_PROP_VOLTAGE_NOW: + /* battery voltage is iio channel * 2 + Vce of transistor */ + iio_read_channel_processed(batt->iio_v, &val->intval); + val->intval *= 2000; + val->intval += 200000; + /* plus adjust for shunt resistor drop */ + iio_read_channel_processed(batt->iio_i, &val2); + val2 *= 1000; + val2 /= 15; + val->intval += val2; + break; + case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN: + val->intval = batt->v_max; + break; + case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN: + val->intval = batt->v_min; + break; + case POWER_SUPPLY_PROP_CURRENT_NOW: + /* battery current is iio channel / 15 / 0.05 ohms */ + iio_read_channel_processed(batt->iio_i, &val->intval); + val->intval *= 20000; + val->intval /= 15; + break; + case POWER_SUPPLY_PROP_SCOPE: + val->intval = POWER_SUPPLY_SCOPE_SYSTEM; + break; + default: + return -EINVAL; + } + + return 0; +} + +static int lego_ev3_battery_set_property(struct power_supply *psy, + enum power_supply_property psp, + const union power_supply_propval *val) +{ + struct lego_ev3_battery *batt = power_supply_get_drvdata(psy); + + switch (psp) { + case POWER_SUPPLY_PROP_TECHNOLOGY: + /* + * Only allow changing technology from Unknown to NiMH. Li-ion + * batteries are automatically detected and should not be + * overridden. Rechargeable AA batteries, on the other hand, + * cannot be automatically detected, and so must be manually + * specified. This should only be set once during system init, + * so there is no mechanism to go back to Unknown. + */ + if (batt->technology != POWER_SUPPLY_TECHNOLOGY_UNKNOWN) + return -EINVAL; + switch (val->intval) { + case POWER_SUPPLY_TECHNOLOGY_NiMH: + batt->technology = POWER_SUPPLY_TECHNOLOGY_NiMH; + batt->v_max = 7800000; + batt->v_min = 5400000; + break; + default: + return -EINVAL; + } + break; + default: + return -EINVAL; + } + + return 0; +} + +static int lego_ev3_battery_property_is_writeable(struct power_supply *psy, + enum power_supply_property psp) +{ + struct lego_ev3_battery *batt = power_supply_get_drvdata(psy); + + return psp == POWER_SUPPLY_PROP_TECHNOLOGY && + batt->technology == POWER_SUPPLY_TECHNOLOGY_UNKNOWN; +} + +static enum power_supply_property lego_ev3_battery_props[] = { + POWER_SUPPLY_PROP_TECHNOLOGY, + POWER_SUPPLY_PROP_VOLTAGE_NOW, + POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN, + POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN, + POWER_SUPPLY_PROP_CURRENT_NOW, + POWER_SUPPLY_PROP_SCOPE, +}; + +static const struct power_supply_desc lego_ev3_battery_desc = { + .name = "lego-ev3-battery", + .type = POWER_SUPPLY_TYPE_BATTERY, + .properties = lego_ev3_battery_props, + .num_properties = ARRAY_SIZE(lego_ev3_battery_props), + .get_property = lego_ev3_battery_get_property, + .set_property = lego_ev3_battery_set_property, + .property_is_writeable = lego_ev3_battery_property_is_writeable, +}; + +static int lego_ev3_battery_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct lego_ev3_battery *batt; + struct power_supply_config psy_cfg = {}; + int err; + + batt = devm_kzalloc(dev, sizeof(*batt), GFP_KERNEL); + if (!batt) + return -ENOMEM; + + platform_set_drvdata(pdev, batt); + + batt->iio_v = devm_iio_channel_get(dev, "voltage"); + err = PTR_ERR_OR_ZERO(batt->iio_v); + if (err) { + if (err != -EPROBE_DEFER) + dev_err(dev, "Failed to get voltage iio channel\n"); + return err; + } + + batt->iio_i = devm_iio_channel_get(dev, "current"); + err = PTR_ERR_OR_ZERO(batt->iio_i); + if (err) { + if (err != -EPROBE_DEFER) + dev_err(dev, "Failed to get current iio channel\n"); + return err; + } + + batt->rechargeable_gpio = devm_gpiod_get(dev, "rechargeable", GPIOD_IN); + err = PTR_ERR_OR_ZERO(batt->rechargeable_gpio); + if (err) { + if (err != -EPROBE_DEFER) + dev_err(dev, "Failed to get rechargeable gpio\n"); + return err; + } + + /* + * The rechargeable battery indication switch cannot be changed without + * removing the battery, so we only need to read it once. + */ + if (gpiod_get_value(batt->rechargeable_gpio)) { + /* 2-cell Li-ion, 7.4V nominal */ + batt->technology = POWER_SUPPLY_TECHNOLOGY_LION; + batt->v_max = 84000000; + batt->v_min = 60000000; + } else { + /* 6x AA Alkaline, 9V nominal */ + batt->technology = POWER_SUPPLY_TECHNOLOGY_UNKNOWN; + batt->v_max = 90000000; + batt->v_min = 48000000; + } + + psy_cfg.of_node = pdev->dev.of_node; + psy_cfg.drv_data = batt; + + batt->psy = devm_power_supply_register(dev, &lego_ev3_battery_desc, + &psy_cfg); + err = PTR_ERR_OR_ZERO(batt->psy); + if (err) { + dev_err(dev, "failed to register power supply\n"); + return err; + } + + return 0; +} + +static const struct of_device_id of_lego_ev3_battery_match[] = { + { .compatible = "lego,ev3-battery", }, + { } +}; +MODULE_DEVICE_TABLE(of, of_lego_ev3_battery_match); + +static struct platform_driver lego_ev3_battery_driver = { + .driver = { + .name = "lego-ev3-battery", + .of_match_table = of_lego_ev3_battery_match, + }, + .probe = lego_ev3_battery_probe, +}; +module_platform_driver(lego_ev3_battery_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("David Lechner <david@lechnology.com>"); +MODULE_DESCRIPTION("LEGO MINDSTORMS EV3 Battery Driver"); |
