--- /dev/null
+/*
+ * 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");
projects / GitHub / moto-9609 / android_kernel_motorola_exynos9610.git / commitdiff