text: // SPDX-License-Identifier: GPL-2.0
  /*
   * Battery driver for the Ingenic JZ47xx SoCs
   * Copyright (c) 2019 Artur Rojek <contact@artur-rojek.eu>
   *
   * based on drivers/power/supply/jz4740-battery.c
   */
  
  #include <linux/iio/consumer.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/platform_device.h>
  #include <linux/power_supply.h>
  #include <linux/property.h>
  
  struct ingenic_battery {
  	struct device *dev;
  	struct iio_channel *channel;
  	struct power_supply_desc desc;
  	struct power_supply *battery;
  	struct power_supply_battery_info info;
  };
  
  static int ingenic_battery_get_property(struct power_supply *psy,
  					enum power_supply_property psp,
  					union power_supply_propval *val)
  {
  	struct ingenic_battery *bat = power_supply_get_drvdata(psy);
  	struct power_supply_battery_info *info = &bat->info;
  	int ret;
  
  	switch (psp) {
  	case POWER_SUPPLY_PROP_HEALTH:
  		ret = iio_read_channel_processed(bat->channel, &val->intval);
  		val->intval *= 1000;
  		if (val->intval < info->voltage_min_design_uv)
  			val->intval = POWER_SUPPLY_HEALTH_DEAD;
  		else if (val->intval > info->voltage_max_design_uv)
  			val->intval = POWER_SUPPLY_HEALTH_OVERVOLTAGE;
  		else
  			val->intval = POWER_SUPPLY_HEALTH_GOOD;
  		return ret;
  	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
  		ret = iio_read_channel_processed(bat->channel, &val->intval);
  		val->intval *= 1000;
  		return ret;
  	case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
  		val->intval = info->voltage_min_design_uv;
  		return 0;
  	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
  		val->intval = info->voltage_max_design_uv;
  		return 0;
  	default:
  		return -EINVAL;
  	};
  }
  
  /* Set the most appropriate IIO channel voltage reference scale
   * based on the battery's max voltage.
   */
  static int ingenic_battery_set_scale(struct ingenic_battery *bat)
  {
  	const int *scale_raw;
  	int scale_len, scale_type, best_idx = -1, best_mV, max_raw, i, ret;
  	u64 max_mV;
  
  	ret = iio_read_max_channel_raw(bat->channel, &max_raw);
  	if (ret) {
  		dev_err(bat->dev, "Unable to read max raw channel value\n");
  		return ret;
  	}
  
  	ret = iio_read_avail_channel_attribute(bat->channel, &scale_raw,
  					       &scale_type, &scale_len,
  					       IIO_CHAN_INFO_SCALE);
  	if (ret < 0) {
  		dev_err(bat->dev, "Unable to read channel avail scale\n");
  		return ret;
  	}
  	if (ret != IIO_AVAIL_LIST || scale_type != IIO_VAL_FRACTIONAL_LOG2)
  		return -EINVAL;
  
  	max_mV = bat->info.voltage_max_design_uv / 1000;
  
  	for (i = 0; i < scale_len; i += 2) {
  		u64 scale_mV = (max_raw * scale_raw[i]) >> scale_raw[i + 1];
  
  		if (scale_mV < max_mV)
  			continue;
  
  		if (best_idx >= 0 && scale_mV > best_mV)
  			continue;
  
  		best_mV = scale_mV;
  		best_idx = i;
  	}
  
  	if (best_idx < 0) {
  		dev_err(bat->dev, "Unable to find matching voltage scale\n");
  		return -EINVAL;
  	}
  
  	return iio_write_channel_attribute(bat->channel,
  					   scale_raw[best_idx],
  					   scale_raw[best_idx + 1],
  					   IIO_CHAN_INFO_SCALE);
  }
  
  static enum power_supply_property ingenic_battery_properties[] = {
  	POWER_SUPPLY_PROP_HEALTH,
  	POWER_SUPPLY_PROP_VOLTAGE_NOW,
  	POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN,
  	POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
  };
  
  static int ingenic_battery_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	struct ingenic_battery *bat;
  	struct power_supply_config psy_cfg = {};
  	struct power_supply_desc *desc;
  	int ret;
  
  	bat = devm_kzalloc(dev, sizeof(*bat), GFP_KERNEL);
  	if (!bat)
  		return -ENOMEM;
  
  	bat->dev = dev;
  	bat->channel = devm_iio_channel_get(dev, "battery");
  	if (IS_ERR(bat->channel))
  		return PTR_ERR(bat->channel);
  
  	desc = &bat->desc;
  	desc->name = "jz-battery";
  	desc->type = POWER_SUPPLY_TYPE_BATTERY;
  	desc->properties = ingenic_battery_properties;
  	desc->num_properties = ARRAY_SIZE(ingenic_battery_properties);
  	desc->get_property = ingenic_battery_get_property;
  	psy_cfg.drv_data = bat;
  	psy_cfg.of_node = dev->of_node;
  
  	bat->battery = devm_power_supply_register(dev, desc, &psy_cfg);
  	if (IS_ERR(bat->battery)) {
  		dev_err(dev, "Unable to register battery\n");
  		return PTR_ERR(bat->battery);
  	}
  
  	ret = power_supply_get_battery_info(bat->battery, &bat->info);
  	if (ret) {
  		dev_err(dev, "Unable to get battery info: %d\n", ret);
  		return ret;
  	}
  	if (bat->info.voltage_min_design_uv < 0) {
  		dev_err(dev, "Unable to get voltage min design\n");
  		return bat->info.voltage_min_design_uv;
  	}
  	if (bat->info.voltage_max_design_uv < 0) {
  		dev_err(dev, "Unable to get voltage max design\n");
  		return bat->info.voltage_max_design_uv;
  	}
  
  	return ingenic_battery_set_scale(bat);
  }
  
  #ifdef CONFIG_OF
  static const struct of_device_id ingenic_battery_of_match[] = {
  	{ .compatible = "ingenic,jz4740-battery", },
  	{ },
  };
  MODULE_DEVICE_TABLE(of, ingenic_battery_of_match);
  #endif
  
  static struct platform_driver ingenic_battery_driver = {
  	.driver = {
  		.name = "ingenic-battery",
  		.of_match_table = of_match_ptr(ingenic_battery_of_match),
  	},
  	.probe = ingenic_battery_probe,
  };
  module_platform_driver(ingenic_battery_driver);
  
  MODULE_DESCRIPTION("Battery driver for Ingenic JZ47xx SoCs");
  MODULE_AUTHOR("Artur Rojek <contact@artur-rojek.eu>");
  MODULE_LICENSE("GPL");
  