/*
   * max8660.c  --  Voltage regulation for the Maxim 8660/8661
   *
   * based on max1586.c and wm8400-regulator.c
   *
   * Copyright (C) 2009 Wolfram Sang, Pengutronix e.K.
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License as published by the Free
   * Software Foundation; version 2 of the License.
   *
   * This program is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   *
   * You should have received a copy of the GNU General Public License along with
   * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
   * Place, Suite 330, Boston, MA  02111-1307  USA
   *
   * Some info:
   *
   * Datasheet: http://datasheets.maxim-ic.com/en/ds/MAX8660-MAX8661.pdf
   *
   * This chip is a bit nasty because it is a write-only device. Thus, the driver
   * uses shadow registers to keep track of its values. The main problem appears
   * to be the initialization: When Linux boots up, we cannot know if the chip is
   * in the default state or not, so we would have to pass such information in
   * platform_data. As this adds a bit of complexity to the driver, this is left
   * out for now until it is really needed.
   *
   * [A|S|M]DTV1 registers are currently not used, but [A|S|M]DTV2.
   *
   * If the driver is feature complete, it might be worth to check if one set of
   * functions for V3-V7 is sufficient. For maximum flexibility during
   * development, they are separated for now.
   *
   */
  
  #include <linux/module.h>
  #include <linux/err.h>
  #include <linux/i2c.h>
  #include <linux/platform_device.h>
  #include <linux/regulator/driver.h>
  #include <linux/slab.h>
  #include <linux/regulator/max8660.h>
  #include <linux/of.h>
  #include <linux/of_device.h>
  #include <linux/regulator/of_regulator.h>
  
  #define MAX8660_DCDC_MIN_UV	 725000
  #define MAX8660_DCDC_MAX_UV	1800000
  #define MAX8660_DCDC_STEP	  25000
  #define MAX8660_DCDC_MAX_SEL	0x2b
  
  #define MAX8660_LDO5_MIN_UV	1700000
  #define MAX8660_LDO5_MAX_UV	2000000
  #define MAX8660_LDO5_STEP	  25000
  #define MAX8660_LDO5_MAX_SEL	0x0c
  
  #define MAX8660_LDO67_MIN_UV	1800000
  #define MAX8660_LDO67_MAX_UV	3300000
  #define MAX8660_LDO67_STEP	 100000
  #define MAX8660_LDO67_MAX_SEL	0x0f
  
  enum {
  	MAX8660_OVER1,
  	MAX8660_OVER2,
  	MAX8660_VCC1,
  	MAX8660_ADTV1,
  	MAX8660_ADTV2,
  	MAX8660_SDTV1,
  	MAX8660_SDTV2,
  	MAX8660_MDTV1,
  	MAX8660_MDTV2,
  	MAX8660_L12VCR,
  	MAX8660_FPWM,
  	MAX8660_N_REGS,	/* not a real register */
  };
  
  struct max8660 {
  	struct i2c_client *client;
  	u8 shadow_regs[MAX8660_N_REGS];		/* as chip is write only */
  };
  
  static int max8660_write(struct max8660 *max8660, u8 reg, u8 mask, u8 val)
  {
  	static const u8 max8660_addresses[MAX8660_N_REGS] = {
  	 0x10, 0x12, 0x20, 0x23, 0x24, 0x29, 0x2a, 0x32, 0x33, 0x39, 0x80
  	};
  
  	int ret;
  	u8 reg_val = (max8660->shadow_regs[reg] & mask) | val;
  
  	dev_vdbg(&max8660->client->dev, "Writing reg %02x with %02x
  ",
  			max8660_addresses[reg], reg_val);
  
  	ret = i2c_smbus_write_byte_data(max8660->client,
  			max8660_addresses[reg], reg_val);
  	if (ret == 0)
  		max8660->shadow_regs[reg] = reg_val;
  
  	return ret;
  }
  
  
  /*
   * DCDC functions
   */
  
  static int max8660_dcdc_is_enabled(struct regulator_dev *rdev)
  {
  	struct max8660 *max8660 = rdev_get_drvdata(rdev);
  	u8 val = max8660->shadow_regs[MAX8660_OVER1];
  	u8 mask = (rdev_get_id(rdev) == MAX8660_V3) ? 1 : 4;
  
  	return !!(val & mask);
  }
  
  static int max8660_dcdc_enable(struct regulator_dev *rdev)
  {
  	struct max8660 *max8660 = rdev_get_drvdata(rdev);
  	u8 bit = (rdev_get_id(rdev) == MAX8660_V3) ? 1 : 4;
  
  	return max8660_write(max8660, MAX8660_OVER1, 0xff, bit);
  }
  
  static int max8660_dcdc_disable(struct regulator_dev *rdev)
  {
  	struct max8660 *max8660 = rdev_get_drvdata(rdev);
  	u8 mask = (rdev_get_id(rdev) == MAX8660_V3) ? ~1 : ~4;
  
  	return max8660_write(max8660, MAX8660_OVER1, mask, 0);
  }
  
  static int max8660_dcdc_get_voltage_sel(struct regulator_dev *rdev)
  {
  	struct max8660 *max8660 = rdev_get_drvdata(rdev);
  	u8 reg = (rdev_get_id(rdev) == MAX8660_V3) ? MAX8660_ADTV2 : MAX8660_SDTV2;
  	u8 selector = max8660->shadow_regs[reg];
  
  	return selector;
  }
  
  static int max8660_dcdc_set_voltage_sel(struct regulator_dev *rdev,
  					unsigned int selector)
  {
  	struct max8660 *max8660 = rdev_get_drvdata(rdev);
  	u8 reg, bits;
  	int ret;
  
  	reg = (rdev_get_id(rdev) == MAX8660_V3) ? MAX8660_ADTV2 : MAX8660_SDTV2;
  	ret = max8660_write(max8660, reg, 0, selector);
  	if (ret)
  		return ret;
  
  	/* Select target voltage register and activate regulation */
  	bits = (rdev_get_id(rdev) == MAX8660_V3) ? 0x03 : 0x30;
  	return max8660_write(max8660, MAX8660_VCC1, 0xff, bits);
  }
  
  static struct regulator_ops max8660_dcdc_ops = {
  	.is_enabled = max8660_dcdc_is_enabled,
  	.list_voltage = regulator_list_voltage_linear,
  	.map_voltage = regulator_map_voltage_linear,
  	.set_voltage_sel = max8660_dcdc_set_voltage_sel,
  	.get_voltage_sel = max8660_dcdc_get_voltage_sel,
  };
  
  
  /*
   * LDO5 functions
   */
  
  static int max8660_ldo5_get_voltage_sel(struct regulator_dev *rdev)
  {
  	struct max8660 *max8660 = rdev_get_drvdata(rdev);
  
  	u8 selector = max8660->shadow_regs[MAX8660_MDTV2];
  	return selector;
  }
  
  static int max8660_ldo5_set_voltage_sel(struct regulator_dev *rdev,
  					unsigned int selector)
  {
  	struct max8660 *max8660 = rdev_get_drvdata(rdev);
  	int ret;
  
  	ret = max8660_write(max8660, MAX8660_MDTV2, 0, selector);
  	if (ret)
  		return ret;
  
  	/* Select target voltage register and activate regulation */
  	return max8660_write(max8660, MAX8660_VCC1, 0xff, 0xc0);
  }
  
  static struct regulator_ops max8660_ldo5_ops = {
  	.list_voltage = regulator_list_voltage_linear,
  	.map_voltage = regulator_map_voltage_linear,
  	.set_voltage_sel = max8660_ldo5_set_voltage_sel,
  	.get_voltage_sel = max8660_ldo5_get_voltage_sel,
  };
  
  
  /*
   * LDO67 functions
   */
  
  static int max8660_ldo67_is_enabled(struct regulator_dev *rdev)
  {
  	struct max8660 *max8660 = rdev_get_drvdata(rdev);
  	u8 val = max8660->shadow_regs[MAX8660_OVER2];
  	u8 mask = (rdev_get_id(rdev) == MAX8660_V6) ? 2 : 4;
  
  	return !!(val & mask);
  }
  
  static int max8660_ldo67_enable(struct regulator_dev *rdev)
  {
  	struct max8660 *max8660 = rdev_get_drvdata(rdev);
  	u8 bit = (rdev_get_id(rdev) == MAX8660_V6) ? 2 : 4;
  
  	return max8660_write(max8660, MAX8660_OVER2, 0xff, bit);
  }
  
  static int max8660_ldo67_disable(struct regulator_dev *rdev)
  {
  	struct max8660 *max8660 = rdev_get_drvdata(rdev);
  	u8 mask = (rdev_get_id(rdev) == MAX8660_V6) ? ~2 : ~4;
  
  	return max8660_write(max8660, MAX8660_OVER2, mask, 0);
  }
  
  static int max8660_ldo67_get_voltage_sel(struct regulator_dev *rdev)
  {
  	struct max8660 *max8660 = rdev_get_drvdata(rdev);
  	u8 shift = (rdev_get_id(rdev) == MAX8660_V6) ? 0 : 4;
  	u8 selector = (max8660->shadow_regs[MAX8660_L12VCR] >> shift) & 0xf;
  
  	return selector;
  }
  
  static int max8660_ldo67_set_voltage_sel(struct regulator_dev *rdev,
  					 unsigned int selector)
  {
  	struct max8660 *max8660 = rdev_get_drvdata(rdev);
  
  	if (rdev_get_id(rdev) == MAX8660_V6)
  		return max8660_write(max8660, MAX8660_L12VCR, 0xf0, selector);
  	else
  		return max8660_write(max8660, MAX8660_L12VCR, 0x0f,
  				     selector << 4);
  }
  
  static struct regulator_ops max8660_ldo67_ops = {
  	.is_enabled = max8660_ldo67_is_enabled,
  	.enable = max8660_ldo67_enable,
  	.disable = max8660_ldo67_disable,
  	.list_voltage = regulator_list_voltage_linear,
  	.map_voltage = regulator_map_voltage_linear,
  	.get_voltage_sel = max8660_ldo67_get_voltage_sel,
  	.set_voltage_sel = max8660_ldo67_set_voltage_sel,
  };
  
  static const struct regulator_desc max8660_reg[] = {
  	{
  		.name = "V3(DCDC)",
  		.id = MAX8660_V3,
  		.ops = &max8660_dcdc_ops,
  		.type = REGULATOR_VOLTAGE,
  		.n_voltages = MAX8660_DCDC_MAX_SEL + 1,
  		.owner = THIS_MODULE,
  		.min_uV = MAX8660_DCDC_MIN_UV,
  		.uV_step = MAX8660_DCDC_STEP,
  	},
  	{
  		.name = "V4(DCDC)",
  		.id = MAX8660_V4,
  		.ops = &max8660_dcdc_ops,
  		.type = REGULATOR_VOLTAGE,
  		.n_voltages = MAX8660_DCDC_MAX_SEL + 1,
  		.owner = THIS_MODULE,
  		.min_uV = MAX8660_DCDC_MIN_UV,
  		.uV_step = MAX8660_DCDC_STEP,
  	},
  	{
  		.name = "V5(LDO)",
  		.id = MAX8660_V5,
  		.ops = &max8660_ldo5_ops,
  		.type = REGULATOR_VOLTAGE,
  		.n_voltages = MAX8660_LDO5_MAX_SEL + 1,
  		.owner = THIS_MODULE,
  		.min_uV = MAX8660_LDO5_MIN_UV,
  		.uV_step = MAX8660_LDO5_STEP,
  	},
  	{
  		.name = "V6(LDO)",
  		.id = MAX8660_V6,
  		.ops = &max8660_ldo67_ops,
  		.type = REGULATOR_VOLTAGE,
  		.n_voltages = MAX8660_LDO67_MAX_SEL + 1,
  		.owner = THIS_MODULE,
  		.min_uV = MAX8660_LDO67_MIN_UV,
  		.uV_step = MAX8660_LDO67_STEP,
  	},
  	{
  		.name = "V7(LDO)",
  		.id = MAX8660_V7,
  		.ops = &max8660_ldo67_ops,
  		.type = REGULATOR_VOLTAGE,
  		.n_voltages = MAX8660_LDO67_MAX_SEL + 1,
  		.owner = THIS_MODULE,
  		.min_uV = MAX8660_LDO67_MIN_UV,
  		.uV_step = MAX8660_LDO67_STEP,
  	},
  };
  
  enum {
  	MAX8660 = 0,
  	MAX8661 = 1,
  };
  
  #ifdef CONFIG_OF
  static const struct of_device_id max8660_dt_ids[] = {
  	{ .compatible = "maxim,max8660", .data = (void *) MAX8660 },
  	{ .compatible = "maxim,max8661", .data = (void *) MAX8661 },
  	{ }
  };
  MODULE_DEVICE_TABLE(of, max8660_dt_ids);
  
  static int max8660_pdata_from_dt(struct device *dev,
  				 struct device_node **of_node,
  				 struct max8660_platform_data *pdata)
  {
  	int matched, i;
  	struct device_node *np;
  	struct max8660_subdev_data *sub;
  	struct of_regulator_match rmatch[ARRAY_SIZE(max8660_reg)] = { };
  
  	np = of_get_child_by_name(dev->of_node, "regulators");
  	if (!np) {
  		dev_err(dev, "missing 'regulators' subnode in DT
  ");
  		return -EINVAL;
  	}
  
  	for (i = 0; i < ARRAY_SIZE(rmatch); i++)
  		rmatch[i].name = max8660_reg[i].name;
  
  	matched = of_regulator_match(dev, np, rmatch, ARRAY_SIZE(rmatch));
  	of_node_put(np);
  	if (matched <= 0)
  		return matched;
  
  	pdata->subdevs = devm_kzalloc(dev, sizeof(struct max8660_subdev_data) *
  						matched, GFP_KERNEL);
  	if (!pdata->subdevs)
  		return -ENOMEM;
  
  	pdata->num_subdevs = matched;
  	sub = pdata->subdevs;
  
  	for (i = 0; i < matched; i++) {
  		sub->id = i;
  		sub->name = rmatch[i].name;
  		sub->platform_data = rmatch[i].init_data;
  		of_node[i] = rmatch[i].of_node;
  		sub++;
  	}
  
  	return 0;
  }
  #else
  static inline int max8660_pdata_from_dt(struct device *dev,
  					struct device_node **of_node,
  					struct max8660_platform_data *pdata)
  {
  	return 0;
  }
  #endif
  
  static int max8660_probe(struct i2c_client *client,
  				   const struct i2c_device_id *i2c_id)
  {
  	struct device *dev = &client->dev;
  	struct max8660_platform_data pdata_of, *pdata = dev_get_platdata(dev);
  	struct regulator_config config = { };
  	struct max8660 *max8660;
  	int boot_on, i, id, ret = -EINVAL;
  	struct device_node *of_node[MAX8660_V_END];
  	unsigned long type;
  
  	if (dev->of_node && !pdata) {
  		const struct of_device_id *id;
  
  		id = of_match_device(of_match_ptr(max8660_dt_ids), dev);
  		if (!id)
  			return -ENODEV;
  
  		ret = max8660_pdata_from_dt(dev, of_node, &pdata_of);
  		if (ret < 0)
  			return ret;
  
  		pdata = &pdata_of;
  		type = (unsigned long) id->data;
  	} else {
  		type = i2c_id->driver_data;
  		memset(of_node, 0, sizeof(of_node));
  	}
  
  	if (pdata->num_subdevs > MAX8660_V_END) {
  		dev_err(dev, "Too many regulators found!
  ");
  		return -EINVAL;
  	}
  
  	max8660 = devm_kzalloc(dev, sizeof(struct max8660), GFP_KERNEL);
  	if (!max8660)
  		return -ENOMEM;
  
  	max8660->client = client;
  
  	if (pdata->en34_is_high) {
  		/* Simulate always on */
  		max8660->shadow_regs[MAX8660_OVER1] = 5;
  	} else {
  		/* Otherwise devices can be toggled via software */
  		max8660_dcdc_ops.enable = max8660_dcdc_enable;
  		max8660_dcdc_ops.disable = max8660_dcdc_disable;
  	}
  
  	/*
  	 * First, set up shadow registers to prevent glitches. As some
  	 * registers are shared between regulators, everything must be properly
  	 * set up for all regulators in advance.
  	 */
  	max8660->shadow_regs[MAX8660_ADTV1] =
  		max8660->shadow_regs[MAX8660_ADTV2] =
  		max8660->shadow_regs[MAX8660_SDTV1] =
  		max8660->shadow_regs[MAX8660_SDTV2] = 0x1b;
  	max8660->shadow_regs[MAX8660_MDTV1] =
  		max8660->shadow_regs[MAX8660_MDTV2] = 0x04;
  
  	for (i = 0; i < pdata->num_subdevs; i++) {
  
  		if (!pdata->subdevs[i].platform_data)
  			boot_on = false;
  		else
  			boot_on = pdata->subdevs[i].platform_data->constraints.boot_on;
  
  		switch (pdata->subdevs[i].id) {
  		case MAX8660_V3:
  			if (boot_on)
  				max8660->shadow_regs[MAX8660_OVER1] |= 1;
  			break;
  
  		case MAX8660_V4:
  			if (boot_on)
  				max8660->shadow_regs[MAX8660_OVER1] |= 4;
  			break;
  
  		case MAX8660_V5:
  			break;
  
  		case MAX8660_V6:
  			if (boot_on)
  				max8660->shadow_regs[MAX8660_OVER2] |= 2;
  			break;
  
  		case MAX8660_V7:
  			if (type == MAX8661) {
  				dev_err(dev, "Regulator not on this chip!
  ");
  				return -EINVAL;
  			}
  
  			if (boot_on)
  				max8660->shadow_regs[MAX8660_OVER2] |= 4;
  			break;
  
  		default:
  			dev_err(dev, "invalid regulator %s
  ",
  				 pdata->subdevs[i].name);
  			return ret;
  		}
  	}
  
  	/* Finally register devices */
  	for (i = 0; i < pdata->num_subdevs; i++) {
  		struct regulator_dev *rdev;
  
  		id = pdata->subdevs[i].id;
  
  		config.dev = dev;
  		config.init_data = pdata->subdevs[i].platform_data;
  		config.of_node = of_node[i];
  		config.driver_data = max8660;
  
  		rdev = devm_regulator_register(&client->dev,
  						  &max8660_reg[id], &config);
  		if (IS_ERR(rdev)) {
  			ret = PTR_ERR(rdev);
  			dev_err(&client->dev, "failed to register %s
  ",
  				max8660_reg[id].name);
  			return PTR_ERR(rdev);
  		}
  	}
  
  	i2c_set_clientdata(client, max8660);
  	return 0;
  }
  
  static const struct i2c_device_id max8660_id[] = {
  	{ .name = "max8660", .driver_data = MAX8660 },
  	{ .name = "max8661", .driver_data = MAX8661 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, max8660_id);
  
  static struct i2c_driver max8660_driver = {
  	.probe = max8660_probe,
  	.driver		= {
  		.name	= "max8660",
  	},
  	.id_table	= max8660_id,
  };
  
  static int __init max8660_init(void)
  {
  	return i2c_add_driver(&max8660_driver);
  }
  subsys_initcall(max8660_init);
  
  static void __exit max8660_exit(void)
  {
  	i2c_del_driver(&max8660_driver);
  }
  module_exit(max8660_exit);
  
  /* Module information */
  MODULE_DESCRIPTION("MAXIM 8660/8661 voltage regulator driver");
  MODULE_AUTHOR("Wolfram Sang");
  MODULE_LICENSE("GPL v2");