text: /*
   * max8952.c - Voltage and current regulation for the Maxim 8952
   *
   * Copyright (C) 2010 Samsung Electronics
   * MyungJoo Ham <myungjoo.ham@samsung.com>
   *
   * 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; either version 2 of the License, or
   * (at your option) any later version.
   *
   * 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
   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/i2c.h>
  #include <linux/err.h>
  #include <linux/platform_device.h>
  #include <linux/regulator/driver.h>
  #include <linux/regulator/max8952.h>
  #include <linux/gpio.h>
  #include <linux/io.h>
  #include <linux/slab.h>
  
  /* Registers */
  enum {
  	MAX8952_REG_MODE0,
  	MAX8952_REG_MODE1,
  	MAX8952_REG_MODE2,
  	MAX8952_REG_MODE3,
  	MAX8952_REG_CONTROL,
  	MAX8952_REG_SYNC,
  	MAX8952_REG_RAMP,
  	MAX8952_REG_CHIP_ID1,
  	MAX8952_REG_CHIP_ID2,
  };
  
  struct max8952_data {
  	struct i2c_client	*client;
  	struct device		*dev;
  	struct max8952_platform_data *pdata;
  	struct regulator_dev	*rdev;
  
  	bool vid0;
  	bool vid1;
  };
  
  static int max8952_read_reg(struct max8952_data *max8952, u8 reg)
  {
  	int ret = i2c_smbus_read_byte_data(max8952->client, reg);
  	if (ret > 0)
  		ret &= 0xff;
  
  	return ret;
  }
  
  static int max8952_write_reg(struct max8952_data *max8952,
  		u8 reg, u8 value)
  {
  	return i2c_smbus_write_byte_data(max8952->client, reg, value);
  }
  
  static int max8952_list_voltage(struct regulator_dev *rdev,
  		unsigned int selector)
  {
  	struct max8952_data *max8952 = rdev_get_drvdata(rdev);
  
  	if (rdev_get_id(rdev) != 0)
  		return -EINVAL;
  
  	return (max8952->pdata->dvs_mode[selector] * 10 + 770) * 1000;
  }
  
  static int max8952_get_voltage_sel(struct regulator_dev *rdev)
  {
  	struct max8952_data *max8952 = rdev_get_drvdata(rdev);
  	u8 vid = 0;
  
  	if (max8952->vid0)
  		vid += 1;
  	if (max8952->vid1)
  		vid += 2;
  
  	return vid;
  }
  
  static int max8952_set_voltage_sel(struct regulator_dev *rdev,
  				   unsigned selector)
  {
  	struct max8952_data *max8952 = rdev_get_drvdata(rdev);
  
  	if (!gpio_is_valid(max8952->pdata->gpio_vid0) ||
  			!gpio_is_valid(max8952->pdata->gpio_vid1)) {
  		/* DVS not supported */
  		return -EPERM;
  	}
  
  	max8952->vid0 = selector & 0x1;
  	max8952->vid1 = (selector >> 1) & 0x1;
  	gpio_set_value(max8952->pdata->gpio_vid0, max8952->vid0);
  	gpio_set_value(max8952->pdata->gpio_vid1, max8952->vid1);
  
  	return 0;
  }
  
  static struct regulator_ops max8952_ops = {
  	.list_voltage		= max8952_list_voltage,
  	.get_voltage_sel	= max8952_get_voltage_sel,
  	.set_voltage_sel	= max8952_set_voltage_sel,
  };
  
  static const struct regulator_desc regulator = {
  	.name		= "MAX8952_VOUT",
  	.id		= 0,
  	.n_voltages	= MAX8952_NUM_DVS_MODE,
  	.ops		= &max8952_ops,
  	.type		= REGULATOR_VOLTAGE,
  	.owner		= THIS_MODULE,
  };
  
  static int __devinit max8952_pmic_probe(struct i2c_client *client,
  		const struct i2c_device_id *i2c_id)
  {
  	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
  	struct max8952_platform_data *pdata = client->dev.platform_data;
  	struct regulator_config config = { };
  	struct max8952_data *max8952;
  
  	int ret = 0, err = 0;
  
  	if (!pdata) {
  		dev_err(&client->dev, "Require the platform data\n");
  		return -EINVAL;
  	}
  
  	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
  		return -EIO;
  
  	max8952 = devm_kzalloc(&client->dev, sizeof(struct max8952_data),
  			       GFP_KERNEL);
  	if (!max8952)
  		return -ENOMEM;
  
  	max8952->client = client;
  	max8952->dev = &client->dev;
  	max8952->pdata = pdata;
  
  	config.dev = max8952->dev;
  	config.init_data = &pdata->reg_data;
  	config.driver_data = max8952;
  
  	config.ena_gpio = pdata->gpio_en;
  	if (pdata->reg_data.constraints.boot_on)
  		config.ena_gpio_flags |= GPIOF_OUT_INIT_HIGH;
  
  	max8952->rdev = regulator_register(&regulator, &config);
  
  	if (IS_ERR(max8952->rdev)) {
  		ret = PTR_ERR(max8952->rdev);
  		dev_err(max8952->dev, "regulator init failed (%d)\n", ret);
  		return ret;
  	}
  
  	max8952->vid0 = pdata->default_mode & 0x1;
  	max8952->vid1 = (pdata->default_mode >> 1) & 0x1;
  
  	if (gpio_is_valid(pdata->gpio_vid0) &&
  			gpio_is_valid(pdata->gpio_vid1)) {
  		if (!gpio_request(pdata->gpio_vid0, "MAX8952 VID0"))
  			gpio_direction_output(pdata->gpio_vid0,
  					(pdata->default_mode) & 0x1);
  		else
  			err = 1;
  
  		if (!gpio_request(pdata->gpio_vid1, "MAX8952 VID1"))
  			gpio_direction_output(pdata->gpio_vid1,
  				(pdata->default_mode >> 1) & 0x1);
  		else {
  			if (!err)
  				gpio_free(pdata->gpio_vid0);
  			err = 2;
  		}
  
  	} else
  		err = 3;
  
  	if (err) {
  		dev_warn(max8952->dev, "VID0/1 gpio invalid: "
  				"DVS not available.\n");
  		max8952->vid0 = 0;
  		max8952->vid1 = 0;
  		/* Mark invalid */
  		pdata->gpio_vid0 = -1;
  		pdata->gpio_vid1 = -1;
  
  		/* Disable Pulldown of EN only */
  		max8952_write_reg(max8952, MAX8952_REG_CONTROL, 0x60);
  
  		dev_err(max8952->dev, "DVS modes disabled because VID0 and VID1"
  				" do not have proper controls.\n");
  	} else {
  		/*
  		 * Disable Pulldown on EN, VID0, VID1 to reduce
  		 * leakage current of MAX8952 assuming that MAX8952
  		 * is turned on (EN==1). Note that without having VID0/1
  		 * properly connected, turning pulldown off can be
  		 * problematic. Thus, turn this off only when they are
  		 * controllable by GPIO.
  		 */
  		max8952_write_reg(max8952, MAX8952_REG_CONTROL, 0x0);
  	}
  
  	max8952_write_reg(max8952, MAX8952_REG_MODE0,
  			(max8952_read_reg(max8952,
  					  MAX8952_REG_MODE0) & 0xC0) |
  			(pdata->dvs_mode[0] & 0x3F));
  	max8952_write_reg(max8952, MAX8952_REG_MODE1,
  			(max8952_read_reg(max8952,
  					  MAX8952_REG_MODE1) & 0xC0) |
  			(pdata->dvs_mode[1] & 0x3F));
  	max8952_write_reg(max8952, MAX8952_REG_MODE2,
  			(max8952_read_reg(max8952,
  					  MAX8952_REG_MODE2) & 0xC0) |
  			(pdata->dvs_mode[2] & 0x3F));
  	max8952_write_reg(max8952, MAX8952_REG_MODE3,
  			(max8952_read_reg(max8952,
  					  MAX8952_REG_MODE3) & 0xC0) |
  			(pdata->dvs_mode[3] & 0x3F));
  
  	max8952_write_reg(max8952, MAX8952_REG_SYNC,
  			(max8952_read_reg(max8952, MAX8952_REG_SYNC) & 0x3F) |
  			((pdata->sync_freq & 0x3) << 6));
  	max8952_write_reg(max8952, MAX8952_REG_RAMP,
  			(max8952_read_reg(max8952, MAX8952_REG_RAMP) & 0x1F) |
  			((pdata->ramp_speed & 0x7) << 5));
  
  	i2c_set_clientdata(client, max8952);
  
  	return 0;
  }
  
  static int __devexit max8952_pmic_remove(struct i2c_client *client)
  {
  	struct max8952_data *max8952 = i2c_get_clientdata(client);
  	struct max8952_platform_data *pdata = max8952->pdata;
  	struct regulator_dev *rdev = max8952->rdev;
  
  	regulator_unregister(rdev);
  
  	gpio_free(pdata->gpio_vid0);
  	gpio_free(pdata->gpio_vid1);
  	return 0;
  }
  
  static const struct i2c_device_id max8952_ids[] = {
  	{ "max8952", 0 },
  	{ },
  };
  MODULE_DEVICE_TABLE(i2c, max8952_ids);
  
  static struct i2c_driver max8952_pmic_driver = {
  	.probe		= max8952_pmic_probe,
  	.remove		= __devexit_p(max8952_pmic_remove),
  	.driver		= {
  		.name	= "max8952",
  	},
  	.id_table	= max8952_ids,
  };
  
  static int __init max8952_pmic_init(void)
  {
  	return i2c_add_driver(&max8952_pmic_driver);
  }
  subsys_initcall(max8952_pmic_init);
  
  static void __exit max8952_pmic_exit(void)
  {
  	i2c_del_driver(&max8952_pmic_driver);
  }
  module_exit(max8952_pmic_exit);
  
  MODULE_DESCRIPTION("MAXIM 8952 voltage regulator driver");
  MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
  MODULE_LICENSE("GPL");
  