drivers/hwmon/pmbus/ltc2978.c - kernel/lockdown - Git at Google

 /*
  * 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\n", chip_id);
 		return -ENODEV;
 	}
 	if (data->id != id->driver_data)
 		dev_warn(&client->dev,
 			 "Device mismatch: Configured %s, detected %s\n",
 			 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");
	/*
	* 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\n", chip_id);
	return -ENODEV;
	}
	if (data->id != id->driver_data)
	dev_warn(&client->dev,
	"Device mismatch: Configured %s, detected %s\n",
	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");