text: /*
   * Maxim MAX14656 / AL32 USB Charger Detector driver
   *
   * Copyright (C) 2014 LG Electronics, Inc
   * Copyright (C) 2016 Alexander Kurz <akurz@blala.de>
   *
   * Components from Maxim AL32 Charger detection Driver for MX50 Yoshi Board
   * Copyright (C) Amazon Technologies Inc. All rights reserved.
   * Manish Lachwani (lachwani@lab126.com)
   *
   * This package is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 and
   * only version 2 as published by the Free Software Foundation.
   *
   */
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/delay.h>
  #include <linux/i2c.h>
  #include <linux/interrupt.h>
  #include <linux/slab.h>
  #include <linux/gpio.h>
  #include <linux/of_gpio.h>
  #include <linux/of_device.h>
  #include <linux/workqueue.h>
  #include <linux/power_supply.h>
  
  #define MAX14656_MANUFACTURER	"Maxim Integrated"
  #define MAX14656_NAME		"max14656"
  
  #define MAX14656_DEVICE_ID	0x00
  #define MAX14656_INTERRUPT_1	0x01
  #define MAX14656_INTERRUPT_2	0x02
  #define MAX14656_STATUS_1	0x03
  #define MAX14656_STATUS_2	0x04
  #define MAX14656_INTMASK_1	0x05
  #define MAX14656_INTMASK_2	0x06
  #define MAX14656_CONTROL_1	0x07
  #define MAX14656_CONTROL_2	0x08
  #define MAX14656_CONTROL_3	0x09
  
  #define DEVICE_VENDOR_MASK	0xf0
  #define DEVICE_REV_MASK		0x0f
  #define INT_EN_REG_MASK		BIT(4)
  #define CHG_TYPE_INT_MASK	BIT(0)
  #define STATUS1_VB_VALID_MASK	BIT(4)
  #define STATUS1_CHG_TYPE_MASK	0xf
  #define INT1_DCD_TIMEOUT_MASK	BIT(7)
  #define CONTROL1_DEFAULT	0x0d
  #define CONTROL1_INT_EN		BIT(4)
  #define CONTROL1_INT_ACTIVE_HIGH	BIT(5)
  #define CONTROL1_EDGE		BIT(7)
  #define CONTROL2_DEFAULT	0x8e
  #define CONTROL2_ADC_EN		BIT(0)
  #define CONTROL3_DEFAULT	0x8d
  
  enum max14656_chg_type {
  	MAX14656_NO_CHARGER	= 0,
  	MAX14656_SDP_CHARGER,
  	MAX14656_CDP_CHARGER,
  	MAX14656_DCP_CHARGER,
  	MAX14656_APPLE_500MA_CHARGER,
  	MAX14656_APPLE_1A_CHARGER,
  	MAX14656_APPLE_2A_CHARGER,
  	MAX14656_SPECIAL_500MA_CHARGER,
  	MAX14656_APPLE_12W,
  	MAX14656_CHARGER_LAST
  };
  
  static const struct max14656_chg_type_props {
  	enum power_supply_type type;
  } chg_type_props[] = {
  	{ POWER_SUPPLY_TYPE_UNKNOWN },
  	{ POWER_SUPPLY_TYPE_USB },
  	{ POWER_SUPPLY_TYPE_USB_CDP },
  	{ POWER_SUPPLY_TYPE_USB_DCP },
  	{ POWER_SUPPLY_TYPE_USB_DCP },
  	{ POWER_SUPPLY_TYPE_USB_DCP },
  	{ POWER_SUPPLY_TYPE_USB_DCP },
  	{ POWER_SUPPLY_TYPE_USB_DCP },
  	{ POWER_SUPPLY_TYPE_USB },
  };
  
  struct max14656_chip {
  	struct i2c_client	*client;
  	struct power_supply	*detect_psy;
  	struct power_supply_desc psy_desc;
  	struct delayed_work	irq_work;
  
  	int irq;
  	int online;
  };
  
  static int max14656_read_reg(struct i2c_client *client, int reg, u8 *val)
  {
  	s32 ret;
  
  	ret = i2c_smbus_read_byte_data(client, reg);
  	if (ret < 0) {
  		dev_err(&client->dev,
  			"i2c read fail: can't read from %02x: %d\n",
  			reg, ret);
  		return ret;
  	}
  	*val = ret;
  	return 0;
  }
  
  static int max14656_write_reg(struct i2c_client *client, int reg, u8 val)
  {
  	s32 ret;
  
  	ret = i2c_smbus_write_byte_data(client, reg, val);
  	if (ret < 0) {
  		dev_err(&client->dev,
  			"i2c write fail: can't write %02x to %02x: %d\n",
  			val, reg, ret);
  		return ret;
  	}
  	return 0;
  }
  
  static int max14656_read_block_reg(struct i2c_client *client, u8 reg,
  				  u8 length, u8 *val)
  {
  	int ret;
  
  	ret = i2c_smbus_read_i2c_block_data(client, reg, length, val);
  	if (ret < 0) {
  		dev_err(&client->dev, "failed to block read reg 0x%x: %d\n",
  				reg, ret);
  		return ret;
  	}
  
  	return 0;
  }
  
  #define        REG_TOTAL_NUM   5
  static void max14656_irq_worker(struct work_struct *work)
  {
  	struct max14656_chip *chip =
  		container_of(work, struct max14656_chip, irq_work.work);
  
  	u8 buf[REG_TOTAL_NUM];
  	u8 chg_type;
  	int ret = 0;
  
  	ret = max14656_read_block_reg(chip->client, MAX14656_DEVICE_ID,
  				      REG_TOTAL_NUM, buf);
  
  	if ((buf[MAX14656_STATUS_1] & STATUS1_VB_VALID_MASK) &&
  		(buf[MAX14656_STATUS_1] & STATUS1_CHG_TYPE_MASK)) {
  		chg_type = buf[MAX14656_STATUS_1] & STATUS1_CHG_TYPE_MASK;
  		if (chg_type < MAX14656_CHARGER_LAST)
  			chip->psy_desc.type = chg_type_props[chg_type].type;
  		else
  			chip->psy_desc.type = POWER_SUPPLY_TYPE_UNKNOWN;
  		chip->online = 1;
  	} else {
  		chip->online = 0;
  		chip->psy_desc.type = POWER_SUPPLY_TYPE_UNKNOWN;
  	}
  
  	power_supply_changed(chip->detect_psy);
  }
  
  static irqreturn_t max14656_irq(int irq, void *dev_id)
  {
  	struct max14656_chip *chip = dev_id;
  
  	schedule_delayed_work(&chip->irq_work, msecs_to_jiffies(100));
  
  	return IRQ_HANDLED;
  }
  
  static int max14656_hw_init(struct max14656_chip *chip)
  {
  	uint8_t val = 0;
  	uint8_t rev;
  	struct i2c_client *client = chip->client;
  
  	if (max14656_read_reg(client, MAX14656_DEVICE_ID, &val))
  		return -ENODEV;
  
  	if ((val & DEVICE_VENDOR_MASK) != 0x20) {
  		dev_err(&client->dev, "wrong vendor ID %d\n",
  			((val & DEVICE_VENDOR_MASK) >> 4));
  		return -ENODEV;
  	}
  	rev = val & DEVICE_REV_MASK;
  
  	/* Turn on ADC_EN */
  	if (max14656_write_reg(client, MAX14656_CONTROL_2, CONTROL2_ADC_EN))
  		return -EINVAL;
  
  	/* turn on interrupts and low power mode */
  	if (max14656_write_reg(client, MAX14656_CONTROL_1,
  		CONTROL1_DEFAULT |
  		CONTROL1_INT_EN |
  		CONTROL1_INT_ACTIVE_HIGH |
  		CONTROL1_EDGE))
  		return -EINVAL;
  
  	if (max14656_write_reg(client, MAX14656_INTMASK_1, 0x3))
  		return -EINVAL;
  
  	if (max14656_write_reg(client, MAX14656_INTMASK_2, 0x1))
  		return -EINVAL;
  
  	dev_info(&client->dev, "detected revision %d\n", rev);
  	return 0;
  }
  
  static int max14656_get_property(struct power_supply *psy,
  			    enum power_supply_property psp,
  			    union power_supply_propval *val)
  {
  	struct max14656_chip *chip = power_supply_get_drvdata(psy);
  
  	switch (psp) {
  	case POWER_SUPPLY_PROP_ONLINE:
  		val->intval = chip->online;
  		break;
  	case POWER_SUPPLY_PROP_MODEL_NAME:
  		val->strval = MAX14656_NAME;
  		break;
  	case POWER_SUPPLY_PROP_MANUFACTURER:
  		val->strval = MAX14656_MANUFACTURER;
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  static enum power_supply_property max14656_battery_props[] = {
  	POWER_SUPPLY_PROP_ONLINE,
  	POWER_SUPPLY_PROP_MODEL_NAME,
  	POWER_SUPPLY_PROP_MANUFACTURER,
  };
  
  static int max14656_probe(struct i2c_client *client,
  			  const struct i2c_device_id *id)
  {
  	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
  	struct device *dev = &client->dev;
  	struct power_supply_config psy_cfg = {};
  	struct max14656_chip *chip;
  	int irq = client->irq;
  	int ret = 0;
  
  	if (irq <= 0) {
  		dev_err(dev, "invalid irq number: %d\n", irq);
  		return -ENODEV;
  	}
  
  	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) {
  		dev_err(dev, "No support for SMBUS_BYTE_DATA\n");
  		return -ENODEV;
  	}
  
  	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
  	if (!chip)
  		return -ENOMEM;
  
  	psy_cfg.drv_data = chip;
  	chip->client = client;
  	chip->online = 0;
  	chip->psy_desc.name = MAX14656_NAME;
  	chip->psy_desc.type = POWER_SUPPLY_TYPE_UNKNOWN;
  	chip->psy_desc.properties = max14656_battery_props;
  	chip->psy_desc.num_properties = ARRAY_SIZE(max14656_battery_props);
  	chip->psy_desc.get_property = max14656_get_property;
  	chip->irq = irq;
  
  	ret = max14656_hw_init(chip);
  	if (ret)
  		return -ENODEV;
  
  	INIT_DELAYED_WORK(&chip->irq_work, max14656_irq_worker);
  
  	chip->detect_psy = devm_power_supply_register(dev,
  		       &chip->psy_desc, &psy_cfg);
  	if (IS_ERR(chip->detect_psy)) {
  		dev_err(dev, "power_supply_register failed\n");
  		return -EINVAL;
  	}
  
  	ret = devm_request_irq(dev, chip->irq, max14656_irq,
  			       IRQF_TRIGGER_FALLING,
  			       MAX14656_NAME, chip);
  	if (ret) {
  		dev_err(dev, "request_irq %d failed\n", chip->irq);
  		return -EINVAL;
  	}
  	enable_irq_wake(chip->irq);
  
  	schedule_delayed_work(&chip->irq_work, msecs_to_jiffies(2000));
  
  	return 0;
  }
  
  static const struct i2c_device_id max14656_id[] = {
  	{ "max14656", 0 },
  	{}
  };
  MODULE_DEVICE_TABLE(i2c, max14656_id);
  
  static const struct of_device_id max14656_match_table[] = {
  	{ .compatible = "maxim,max14656", },
  	{}
  };
  MODULE_DEVICE_TABLE(of, max14656_match_table);
  
  static struct i2c_driver max14656_i2c_driver = {
  	.driver = {
  		.name	= "max14656",
  		.of_match_table = max14656_match_table,
  	},
  	.probe		= max14656_probe,
  	.id_table	= max14656_id,
  };
  module_i2c_driver(max14656_i2c_driver);
  
  MODULE_DESCRIPTION("MAX14656 USB charger detector");
  MODULE_LICENSE("GPL v2");
  