/*
   * Hardware monitoring driver for LTC2974, LTC2977, LTC2978, LTC3880,
   * and LTC3883
   *
   * Copyright (c) 2011 Ericsson AB.
   * Copyright (c) 2013 Guenter Roeck
   *
   * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/err.h>
  #include <linux/slab.h>
  #include <linux/i2c.h>
  #include "pmbus.h"
  
  enum chips { ltc2974, ltc2977, ltc2978, ltc3880, ltc3883 };
  
  /* Common for all chips */
  #define LTC2978_MFR_VOUT_PEAK		0xdd
  #define LTC2978_MFR_VIN_PEAK		0xde
  #define LTC2978_MFR_TEMPERATURE_PEAK	0xdf
  #define LTC2978_MFR_SPECIAL_ID		0xe7
  
  /* LTC2974, LCT2977, and LTC2978 */
  #define LTC2978_MFR_VOUT_MIN		0xfb
  #define LTC2978_MFR_VIN_MIN		0xfc
  #define LTC2978_MFR_TEMPERATURE_MIN	0xfd
  
  /* LTC2974 only */
  #define LTC2974_MFR_IOUT_PEAK		0xd7
  #define LTC2974_MFR_IOUT_MIN		0xd8
  
  /* LTC3880 and LTC3883 */
  #define LTC3880_MFR_IOUT_PEAK		0xd7
  #define LTC3880_MFR_CLEAR_PEAKS		0xe3
  #define LTC3880_MFR_TEMPERATURE2_PEAK	0xf4
  
  /* LTC3883 only */
  #define LTC3883_MFR_IIN_PEAK		0xe1
  
  #define LTC2974_ID			0x0212
  #define LTC2977_ID			0x0130
  #define LTC2978_ID_REV1			0x0121
  #define LTC2978_ID_REV2			0x0122
  #define LTC2978A_ID			0x0124
  #define LTC3880_ID			0x4000
  #define LTC3880_ID_MASK			0xff00
  #define LTC3883_ID			0x4300
  #define LTC3883_ID_MASK			0xff00
  
  #define LTC2974_NUM_PAGES		4
  #define LTC2978_NUM_PAGES		8
  #define LTC3880_NUM_PAGES		2
  #define LTC3883_NUM_PAGES		1
  
  /*
   * LTC2978 clears peak data whenever the CLEAR_FAULTS command is executed, which
   * happens pretty much each time chip data is updated. Raw peak data therefore
   * does not provide much value. To be able to provide useful peak data, keep an
   * internal cache of measured peak data, which is only cleared if an explicit
   * "clear peak" command is executed for the sensor in question.
   */
  
  struct ltc2978_data {
  	enum chips id;
  	u16 vin_min, vin_max;
  	u16 temp_min[LTC2974_NUM_PAGES], temp_max[LTC2974_NUM_PAGES];
  	u16 vout_min[LTC2978_NUM_PAGES], vout_max[LTC2978_NUM_PAGES];
  	u16 iout_min[LTC2974_NUM_PAGES], iout_max[LTC2974_NUM_PAGES];
  	u16 iin_max;
  	u16 temp2_max;
  	struct pmbus_driver_info info;
  };
  
  #define to_ltc2978_data(x)  container_of(x, struct ltc2978_data, info)
  
  static inline int lin11_to_val(int data)
  {
  	s16 e = ((s16)data) >> 11;
  	s32 m = (((s16)(data << 5)) >> 5);
  
  	/*
  	 * mantissa is 10 bit + sign, exponent adds up to 15 bit.
  	 * Add 6 bit to exponent for maximum accuracy (10 + 15 + 6 = 31).
  	 */
  	e += 6;
  	return (e < 0 ? m >> -e : m << e);
  }
  
  static int ltc2978_read_word_data_common(struct i2c_client *client, int page,
  					 int reg)
  {
  	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
  	struct ltc2978_data *data = to_ltc2978_data(info);
  	int ret;
  
  	switch (reg) {
  	case PMBUS_VIRT_READ_VIN_MAX:
  		ret = pmbus_read_word_data(client, page, LTC2978_MFR_VIN_PEAK);
  		if (ret >= 0) {
  			if (lin11_to_val(ret) > lin11_to_val(data->vin_max))
  				data->vin_max = ret;
  			ret = data->vin_max;
  		}
  		break;
  	case PMBUS_VIRT_READ_VOUT_MAX:
  		ret = pmbus_read_word_data(client, page, LTC2978_MFR_VOUT_PEAK);
  		if (ret >= 0) {
  			/*
  			 * VOUT is 16 bit unsigned with fixed exponent,
  			 * so we can compare it directly
  			 */
  			if (ret > data->vout_max[page])
  				data->vout_max[page] = ret;
  			ret = data->vout_max[page];
  		}
  		break;
  	case PMBUS_VIRT_READ_TEMP_MAX:
  		ret = pmbus_read_word_data(client, page,
  					   LTC2978_MFR_TEMPERATURE_PEAK);
  		if (ret >= 0) {
  			if (lin11_to_val(ret)
  			    > lin11_to_val(data->temp_max[page]))
  				data->temp_max[page] = ret;
  			ret = data->temp_max[page];
  		}
  		break;
  	case PMBUS_VIRT_RESET_VOUT_HISTORY:
  	case PMBUS_VIRT_RESET_VIN_HISTORY:
  	case PMBUS_VIRT_RESET_TEMP_HISTORY:
  		ret = 0;
  		break;
  	default:
  		ret = -ENODATA;
  		break;
  	}
  	return ret;
  }
  
  static int ltc2978_read_word_data(struct i2c_client *client, int page, int reg)
  {
  	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
  	struct ltc2978_data *data = to_ltc2978_data(info);
  	int ret;
  
  	switch (reg) {
  	case PMBUS_VIRT_READ_VIN_MIN:
  		ret = pmbus_read_word_data(client, page, LTC2978_MFR_VIN_MIN);
  		if (ret >= 0) {
  			if (lin11_to_val(ret) < lin11_to_val(data->vin_min))
  				data->vin_min = ret;
  			ret = data->vin_min;
  		}
  		break;
  	case PMBUS_VIRT_READ_VOUT_MIN:
  		ret = pmbus_read_word_data(client, page, LTC2978_MFR_VOUT_MIN);
  		if (ret >= 0) {
  			/*
  			 * VOUT_MIN is known to not be supported on some lots
  			 * of LTC2978 revision 1, and will return the maximum
  			 * possible voltage if read. If VOUT_MAX is valid and
  			 * lower than the reading of VOUT_MIN, use it instead.
  			 */
  			if (data->vout_max[page] && ret > data->vout_max[page])
  				ret = data->vout_max[page];
  			if (ret < data->vout_min[page])
  				data->vout_min[page] = ret;
  			ret = data->vout_min[page];
  		}
  		break;
  	case PMBUS_VIRT_READ_TEMP_MIN:
  		ret = pmbus_read_word_data(client, page,
  					   LTC2978_MFR_TEMPERATURE_MIN);
  		if (ret >= 0) {
  			if (lin11_to_val(ret)
  			    < lin11_to_val(data->temp_min[page]))
  				data->temp_min[page] = ret;
  			ret = data->temp_min[page];
  		}
  		break;
  	case PMBUS_VIRT_READ_IOUT_MAX:
  	case PMBUS_VIRT_RESET_IOUT_HISTORY:
  	case PMBUS_VIRT_READ_TEMP2_MAX:
  	case PMBUS_VIRT_RESET_TEMP2_HISTORY:
  		ret = -ENXIO;
  		break;
  	default:
  		ret = ltc2978_read_word_data_common(client, page, reg);
  		break;
  	}
  	return ret;
  }
  
  static int ltc2974_read_word_data(struct i2c_client *client, int page, int reg)
  {
  	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
  	struct ltc2978_data *data = to_ltc2978_data(info);
  	int ret;
  
  	switch (reg) {
  	case PMBUS_VIRT_READ_IOUT_MAX:
  		ret = pmbus_read_word_data(client, page, LTC2974_MFR_IOUT_PEAK);
  		if (ret >= 0) {
  			if (lin11_to_val(ret)
  			    > lin11_to_val(data->iout_max[page]))
  				data->iout_max[page] = ret;
  			ret = data->iout_max[page];
  		}
  		break;
  	case PMBUS_VIRT_READ_IOUT_MIN:
  		ret = pmbus_read_word_data(client, page, LTC2974_MFR_IOUT_MIN);
  		if (ret >= 0) {
  			if (lin11_to_val(ret)
  			    < lin11_to_val(data->iout_min[page]))
  				data->iout_min[page] = ret;
  			ret = data->iout_min[page];
  		}
  		break;
  	case PMBUS_VIRT_RESET_IOUT_HISTORY:
  		ret = 0;
  		break;
  	default:
  		ret = ltc2978_read_word_data(client, page, reg);
  		break;
  	}
  	return ret;
  }
  
  static int ltc3880_read_word_data(struct i2c_client *client, int page, int reg)
  {
  	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
  	struct ltc2978_data *data = to_ltc2978_data(info);
  	int ret;
  
  	switch (reg) {
  	case PMBUS_VIRT_READ_IOUT_MAX:
  		ret = pmbus_read_word_data(client, page, LTC3880_MFR_IOUT_PEAK);
  		if (ret >= 0) {
  			if (lin11_to_val(ret)
  			    > lin11_to_val(data->iout_max[page]))
  				data->iout_max[page] = ret;
  			ret = data->iout_max[page];
  		}
  		break;
  	case PMBUS_VIRT_READ_TEMP2_MAX:
  		ret = pmbus_read_word_data(client, page,
  					   LTC3880_MFR_TEMPERATURE2_PEAK);
  		if (ret >= 0) {
  			if (lin11_to_val(ret) > lin11_to_val(data->temp2_max))
  				data->temp2_max = ret;
  			ret = data->temp2_max;
  		}
  		break;
  	case PMBUS_VIRT_READ_VIN_MIN:
  	case PMBUS_VIRT_READ_VOUT_MIN:
  	case PMBUS_VIRT_READ_TEMP_MIN:
  		ret = -ENXIO;
  		break;
  	case PMBUS_VIRT_RESET_IOUT_HISTORY:
  	case PMBUS_VIRT_RESET_TEMP2_HISTORY:
  		ret = 0;
  		break;
  	default:
  		ret = ltc2978_read_word_data_common(client, page, reg);
  		break;
  	}
  	return ret;
  }
  
  static int ltc3883_read_word_data(struct i2c_client *client, int page, int reg)
  {
  	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
  	struct ltc2978_data *data = to_ltc2978_data(info);
  	int ret;
  
  	switch (reg) {
  	case PMBUS_VIRT_READ_IIN_MAX:
  		ret = pmbus_read_word_data(client, page, LTC3883_MFR_IIN_PEAK);
  		if (ret >= 0) {
  			if (lin11_to_val(ret)
  			    > lin11_to_val(data->iin_max))
  				data->iin_max = ret;
  			ret = data->iin_max;
  		}
  		break;
  	case PMBUS_VIRT_RESET_IIN_HISTORY:
  		ret = 0;
  		break;
  	default:
  		ret = ltc3880_read_word_data(client, page, reg);
  		break;
  	}
  	return ret;
  }
  
  static int ltc2978_clear_peaks(struct i2c_client *client, int page,
  			       enum chips id)
  {
  	int ret;
  
  	if (id == ltc3880 || id == ltc3883)
  		ret = pmbus_write_byte(client, 0, LTC3880_MFR_CLEAR_PEAKS);
  	else
  		ret = pmbus_write_byte(client, page, PMBUS_CLEAR_FAULTS);
  
  	return ret;
  }
  
  static int ltc2978_write_word_data(struct i2c_client *client, int page,
  				    int reg, u16 word)
  {
  	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
  	struct ltc2978_data *data = to_ltc2978_data(info);
  	int ret;
  
  	switch (reg) {
  	case PMBUS_VIRT_RESET_IIN_HISTORY:
  		data->iin_max = 0x7c00;
  		ret = ltc2978_clear_peaks(client, page, data->id);
  		break;
  	case PMBUS_VIRT_RESET_IOUT_HISTORY:
  		data->iout_max[page] = 0x7c00;
  		data->iout_min[page] = 0xfbff;
  		ret = ltc2978_clear_peaks(client, page, data->id);
  		break;
  	case PMBUS_VIRT_RESET_TEMP2_HISTORY:
  		data->temp2_max = 0x7c00;
  		ret = ltc2978_clear_peaks(client, page, data->id);
  		break;
  	case PMBUS_VIRT_RESET_VOUT_HISTORY:
  		data->vout_min[page] = 0xffff;
  		data->vout_max[page] = 0;
  		ret = ltc2978_clear_peaks(client, page, data->id);
  		break;
  	case PMBUS_VIRT_RESET_VIN_HISTORY:
  		data->vin_min = 0x7bff;
  		data->vin_max = 0x7c00;
  		ret = ltc2978_clear_peaks(client, page, data->id);
  		break;
  	case PMBUS_VIRT_RESET_TEMP_HISTORY:
  		data->temp_min[page] = 0x7bff;
  		data->temp_max[page] = 0x7c00;
  		ret = ltc2978_clear_peaks(client, page, data->id);
  		break;
  	default:
  		ret = -ENODATA;
  		break;
  	}
  	return ret;
  }
  
  static const struct i2c_device_id ltc2978_id[] = {
  	{"ltc2974", ltc2974},
  	{"ltc2977", ltc2977},
  	{"ltc2978", ltc2978},
  	{"ltc3880", ltc3880},
  	{"ltc3883", ltc3883},
  	{}
  };
  MODULE_DEVICE_TABLE(i2c, ltc2978_id);
  
  static int ltc2978_probe(struct i2c_client *client,
  			 const struct i2c_device_id *id)
  {
  	int chip_id, i;
  	struct ltc2978_data *data;
  	struct pmbus_driver_info *info;
  
  	if (!i2c_check_functionality(client->adapter,
  				     I2C_FUNC_SMBUS_READ_WORD_DATA))
  		return -ENODEV;
  
  	data = devm_kzalloc(&client->dev, sizeof(struct ltc2978_data),
  			    GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	chip_id = i2c_smbus_read_word_data(client, LTC2978_MFR_SPECIAL_ID);
  	if (chip_id < 0)
  		return chip_id;
  
  	if (chip_id == LTC2974_ID) {
  		data->id = ltc2974;
  	} else if (chip_id == LTC2977_ID) {
  		data->id = ltc2977;
  	} else if (chip_id == LTC2978_ID_REV1 || chip_id == LTC2978_ID_REV2 ||
  		   chip_id == LTC2978A_ID) {
  		data->id = ltc2978;
  	} else if ((chip_id & LTC3880_ID_MASK) == LTC3880_ID) {
  		data->id = ltc3880;
  	} else if ((chip_id & LTC3883_ID_MASK) == LTC3883_ID) {
  		data->id = ltc3883;
  	} else {
  		dev_err(&client->dev, "Unsupported chip ID 0x%x
  ", chip_id);
  		return -ENODEV;
  	}
  	if (data->id != id->driver_data)
  		dev_warn(&client->dev,
  			 "Device mismatch: Configured %s, detected %s
  ",
  			 id->name,
  			 ltc2978_id[data->id].name);
  
  	info = &data->info;
  	info->write_word_data = ltc2978_write_word_data;
  
  	data->vin_min = 0x7bff;
  	data->vin_max = 0x7c00;
  	for (i = 0; i < ARRAY_SIZE(data->vout_min); i++)
  		data->vout_min[i] = 0xffff;
  	for (i = 0; i < ARRAY_SIZE(data->iout_min); i++)
  		data->iout_min[i] = 0xfbff;
  	for (i = 0; i < ARRAY_SIZE(data->iout_max); i++)
  		data->iout_max[i] = 0x7c00;
  	for (i = 0; i < ARRAY_SIZE(data->temp_min); i++)
  		data->temp_min[i] = 0x7bff;
  	for (i = 0; i < ARRAY_SIZE(data->temp_max); i++)
  		data->temp_max[i] = 0x7c00;
  	data->temp2_max = 0x7c00;
  
  	switch (data->id) {
  	case ltc2974:
  		info->read_word_data = ltc2974_read_word_data;
  		info->pages = LTC2974_NUM_PAGES;
  		info->func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_STATUS_INPUT
  		  | PMBUS_HAVE_TEMP2;
  		for (i = 0; i < info->pages; i++) {
  			info->func[i] |= PMBUS_HAVE_VOUT
  			  | PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_POUT
  			  | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP
  			  | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT;
  		}
  		break;
  	case ltc2977:
  	case ltc2978:
  		info->read_word_data = ltc2978_read_word_data;
  		info->pages = LTC2978_NUM_PAGES;
  		info->func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_STATUS_INPUT
  		  | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
  		  | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP;
  		for (i = 1; i < LTC2978_NUM_PAGES; i++) {
  			info->func[i] = PMBUS_HAVE_VOUT
  			  | PMBUS_HAVE_STATUS_VOUT;
  		}
  		break;
  	case ltc3880:
  		info->read_word_data = ltc3880_read_word_data;
  		info->pages = LTC3880_NUM_PAGES;
  		info->func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN
  		  | PMBUS_HAVE_STATUS_INPUT
  		  | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
  		  | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT
  		  | PMBUS_HAVE_POUT | PMBUS_HAVE_TEMP
  		  | PMBUS_HAVE_TEMP2 | PMBUS_HAVE_STATUS_TEMP;
  		info->func[1] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
  		  | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT
  		  | PMBUS_HAVE_POUT
  		  | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP;
  		break;
  	case ltc3883:
  		info->read_word_data = ltc3883_read_word_data;
  		info->pages = LTC3883_NUM_PAGES;
  		info->func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN
  		  | PMBUS_HAVE_STATUS_INPUT
  		  | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
  		  | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT
  		  | PMBUS_HAVE_PIN | PMBUS_HAVE_POUT | PMBUS_HAVE_TEMP
  		  | PMBUS_HAVE_TEMP2 | PMBUS_HAVE_STATUS_TEMP;
  		break;
  	default:
  		return -ENODEV;
  	}
  	return pmbus_do_probe(client, id, info);
  }
  
  /* This is the driver that will be inserted */
  static struct i2c_driver ltc2978_driver = {
  	.driver = {
  		   .name = "ltc2978",
  		   },
  	.probe = ltc2978_probe,
  	.remove = pmbus_do_remove,
  	.id_table = ltc2978_id,
  };
  
  module_i2c_driver(ltc2978_driver);
  
  MODULE_AUTHOR("Guenter Roeck");
  MODULE_DESCRIPTION("PMBus driver for LTC2974, LTC2978, LTC3880, and LTC3883");
  MODULE_LICENSE("GPL");