drivers/hwmon/pmbus/mp2856.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Hardware monitoring driver for MPS2856/2857
  * Monolithic Power Systems VR Controllers
  *
  * Copyright (C) 2023 Quanta Computer lnc.
  */

 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pmbus.h>
 #include "pmbus.h"

 /* Vendor specific registers. */
 #define MP2856_MFR_VR_MULTI_CONFIG_R1	0x0d
 #define MP2856_MFR_VR_MULTI_CONFIG_R2	0x1d

 #define MP2856_MUL1_BOOT_SR_R2		0x10
 #define MP2856_VR_ACTIVE		BIT(15)

 #define MP2856_MFR_VR_CONFIG2		0x5e
 #define MP2856_VOUT_MODE		BIT(11)

 #define MP2856_MFR_VR_CONFIG1		0x68
 #define MP2856_DRMOS_KCS		GENMASK(13, 12)

 #define MP2856_MFR_READ_CS1_2_R1	0x82
 #define MP2856_MFR_READ_CS3_4_R1	0x83
 #define MP2856_MFR_READ_CS5_6_R1	0x84
 #define MP2856_MFR_READ_CS7_8_R1	0x85
 #define MP2856_MFR_READ_CS9_10_R1	0x86
 #define MP2856_MFR_READ_CS11_12_R1	0x87

 #define MP2856_MFR_READ_CS1_2_R2	0x85
 #define MP2856_MFR_READ_CS3_4_R2	0x86
 #define MP2856_MFR_READ_CS5_6_R2	0x87

 #define MP2856_MAX_PHASE_RAIL1		8
 #define MP2856_MAX_PHASE_RAIL2		4

 #define MP2857_MAX_PHASE_RAIL1		12
 #define MP2857_MAX_PHASE_RAIL2		4

 #define MP2856_PAGE_NUM			2

 enum chips { mp2856, mp2857 };

 static const int mp2856_max_phases[][MP2856_PAGE_NUM] = {
 	[mp2856] = { MP2856_MAX_PHASE_RAIL1, MP2856_MAX_PHASE_RAIL2 },
 	[mp2857] = { MP2857_MAX_PHASE_RAIL1, MP2857_MAX_PHASE_RAIL2 },
 };

 static const struct i2c_device_id mp2856_id[] = {
 	{"mp2856", mp2856},
 	{"mp2857", mp2857},
 	{}
 };

 MODULE_DEVICE_TABLE(i2c, mp2856_id);

 struct mp2856_data {
 	struct pmbus_driver_info info;
 	int vout_format[MP2856_PAGE_NUM];
 	int curr_sense_gain[MP2856_PAGE_NUM];
 	int max_phases[MP2856_PAGE_NUM];
 };

 #define to_mp2856_data(x)	container_of(x, struct mp2856_data, info)

 #define MAX_LIN_MANTISSA	(1023 * 1000)
 #define MIN_LIN_MANTISSA	(511 * 1000)

 static u16 val2linear11(s64 val)
 {
 	s16 exponent = 0, mantissa;
 	bool negative = false;

 	if (val == 0)
 		return 0;

 	if (val < 0) {
 		negative = true;
 		val = -val;
 	}

 	/* Reduce large mantissa until it fits into 10 bit */
 	while (val >= MAX_LIN_MANTISSA && exponent < 15) {
 		exponent++;
 		val >>= 1;
 	}
 	/* Increase small mantissa to improve precision */
 	while (val < MIN_LIN_MANTISSA && exponent > -15) {
 		exponent--;
 		val <<= 1;
 	}

 	/* Convert mantissa from milli-units to units */
 	mantissa = clamp_val(DIV_ROUND_CLOSEST_ULL(val, 1000), 0, 0x3ff);

 	/* restore sign */
 	if (negative)
 		mantissa = -mantissa;

 	/* Convert to 5 bit exponent, 11 bit mantissa */
 	return (mantissa & 0x7ff) | ((exponent << 11) & 0xf800);
 }

 static int
 mp2856_read_word_helper(struct i2c_client *client, int page, int phase, u8 reg,
 			u16 mask)
 {
 	int ret = pmbus_read_word_data(client, page, phase, reg);

 	return (ret > 0) ? ret & mask : ret;
 }

 static int
 mp2856_read_vout(struct i2c_client *client, struct mp2856_data *data, int page,
 		 int phase, u8 reg)
 {
 	int ret;

 	ret = mp2856_read_word_helper(client, page, phase, reg,
 				      GENMASK(9, 0));
 	if (ret < 0)
 		return ret;

 	/* convert vout result to direct format */
 	ret = (data->vout_format[page] == vid) ?
 		((ret + 49) * 5) : ((ret * 1000) >> 8);

 	return ret;
 }

 static int
 mp2856_read_phase(struct i2c_client *client, struct mp2856_data *data,
 		  int page, int phase, u8 reg)
 {
 	int ret;
 	int val;

 	ret = pmbus_read_word_data(client, page, phase, reg);
 	if (ret < 0)
 		return ret;

 	if (!((phase + 1) % MP2856_PAGE_NUM))
 		ret >>= 8;
 	ret &= 0xff;

 	/*
 	 * Output value is calculated as: (READ_CSx * 12.5mV - 1.23V) / (Kcs * Rcs)
 	 */
 	val = (ret * 125) - 12300;

 	return val2linear11(val);
 }

 static int
 mp2856_read_phases(struct i2c_client *client, struct mp2856_data *data,
 		   int page, int phase)
 {
 	int ret;

 	if (page == 0) {
 		switch (phase) {
 		case 0 ... 1:
 			ret = mp2856_read_phase(client, data, page, phase,
 						MP2856_MFR_READ_CS1_2_R1);
 			break;
 		case 2 ... 3:
 			ret = mp2856_read_phase(client, data, page, phase,
 						MP2856_MFR_READ_CS3_4_R1);
 			break;
 		case 4 ... 5:
 			ret = mp2856_read_phase(client, data, page, phase,
 						MP2856_MFR_READ_CS5_6_R1);
 			break;
 		case 6 ... 7:
 			ret = mp2856_read_phase(client, data, page, phase,
 						MP2856_MFR_READ_CS7_8_R1);
 			break;
 		default:
 			return -ENODATA;
 		}
 	} else {
 		switch (phase) {
 		case 0 ... 1:
 			ret = mp2856_read_phase(client, data, page, phase,
 						MP2856_MFR_READ_CS1_2_R2);
 			break;
 		case 2 ... 3:
 			ret = mp2856_read_phase(client, data, page, phase,
 						MP2856_MFR_READ_CS1_2_R2);
 			break;
 		default:
 			return -ENODATA;
 		}
 	}
 	return ret;
 }

 static int
 mp2856_read_word_data(struct i2c_client *client, int page,
 		      int phase, int reg)
 {
 	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
 	struct mp2856_data *data = to_mp2856_data(info);
 	int ret;

 	switch (reg) {
 	case PMBUS_READ_VOUT:
 		ret = mp2856_read_vout(client, data, page, phase, reg);
 		break;
 	case PMBUS_READ_IOUT:
 		if (phase != 0xff)
 			ret = mp2856_read_phases(client, data, page, phase);
 		else
 			ret = pmbus_read_word_data(client, page, phase, reg);
 		break;
 	default:
 		return -ENODATA;
 	}

 	return ret;
 }

 static int
 mp2856_read_byte_data(struct i2c_client *client, int page, int reg)
 {
 	switch (reg) {
 	case PMBUS_VOUT_MODE:
 		/* Enforce VOUT direct format. */
 		return PB_VOUT_MODE_DIRECT;
 	default:
 		return -ENODATA;
 	}
 }

 static int
 mp2856_identify_multiphase(struct i2c_client *client, u8 reg, u8 max_phase,
 			   u16 mask)
 {
 	int ret;

 	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
 	if (ret < 0)
 		return ret;

 	ret = i2c_smbus_read_word_data(client, reg);
 	if (ret < 0)
 		return ret;

 	ret &= mask;
 	return (ret >= max_phase) ? max_phase : ret;
 }

 static int
 mp2856_identify_multiphase_rail1(struct i2c_client *client,
 				 struct mp2856_data *data)
 {
 	int ret, i;

 	ret = mp2856_identify_multiphase(client, MP2856_MFR_VR_MULTI_CONFIG_R1,
 					 MP2856_MAX_PHASE_RAIL1, GENMASK(3, 0));
 	if (ret < 0)
 		return ret;

 	data->info.phases[0] = (ret > data->max_phases[0]) ?
 				data->max_phases[0] : ret;

 	for (i = 0 ; i < data->info.phases[0]; i++)
 		data->info.pfunc[i] |= PMBUS_HAVE_IOUT;

 	return 0;
 }

 static int
 mp2856_identify_multiphase_rail2(struct i2c_client *client,
 				 struct mp2856_data *data)
 {
 	int ret, i;

 	ret = mp2856_identify_multiphase(client, MP2856_MFR_VR_MULTI_CONFIG_R2,
 					 MP2856_MAX_PHASE_RAIL2, GENMASK(2, 0));
 	if (ret < 0)
 		return ret;

 	data->info.phases[1] = (ret > data->max_phases[1]) ?
 				data->max_phases[1] : ret;

 	for (i = 0 ; i < data->info.phases[0]; i++)
 		data->info.pfunc[i] |= PMBUS_HAVE_IOUT;

 	return 0;
 }

 static int
 mp2856_current_sense_gain_get(struct i2c_client *client,
 			      struct mp2856_data *data)
 {
 	int i, ret;

 	/*
 	 * Obtain DrMOS current sense gain of power stage from the register
 	 * MP2856_MFR_VR_CONFIG1, bits 13-12. The value is selected as below:
 	 * 00b - 5µA/A, 01b - 8.5µA/A, 10b - 9.7µA/A, 11b - 10µA/A. Other
 	 * values are invalid.
 	 */
 	for (i = 0 ; i < data->info.pages; i++) {
 		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
 		if (ret < 0)
 			return ret;
 		ret = i2c_smbus_read_word_data(client,
 					       MP2856_MFR_VR_CONFIG1);
 		if (ret < 0)
 			return ret;

 		switch ((ret & MP2856_DRMOS_KCS) >> 12) {
 		case 0:
 			data->curr_sense_gain[i] = 50;
 			break;
 		case 1:
 			data->curr_sense_gain[i] = 85;
 			break;
 		case 2:
 			data->curr_sense_gain[i] = 97;
 			break;
 		default:
 			data->curr_sense_gain[i] = 100;
 			break;
 		}
 	}
 	return 0;
 }

 static int
 mp2856_identify_vout_format(struct i2c_client *client,
 			    struct mp2856_data *data)
 {
 	int i, ret;

 	for (i = 0; i < data->info.pages; i++) {
 		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
 		if (ret < 0)
 			return ret;

 		ret = i2c_smbus_read_word_data(client, MP2856_MFR_VR_CONFIG2);
 		if (ret < 0)
 			return ret;

 		data->vout_format[i] = (ret & MP2856_VOUT_MODE) ? linear : vid;
 	}
 	return 0;
 }

 static bool
 mp2856_is_rail2_active(struct i2c_client *client)
 {
 	int ret;

 	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
 	if (ret < 0)
 		return true;

 	ret = i2c_smbus_read_word_data(client, MP2856_MUL1_BOOT_SR_R2);
 	if (ret < 0)
 		return true;

 	return (ret & MP2856_VR_ACTIVE) ? true : false;
 }

 static struct pmbus_driver_info mp2856_info = {
 	.pages = MP2856_PAGE_NUM,
 	.format[PSC_VOLTAGE_IN] = linear,
 	.format[PSC_VOLTAGE_OUT] = direct,
 	.format[PSC_TEMPERATURE] = linear,
 	.format[PSC_CURRENT_IN] = linear,
 	.format[PSC_CURRENT_OUT] = linear,
 	.format[PSC_POWER] = linear,
 	.m[PSC_VOLTAGE_OUT] = 1,
 	.R[PSC_VOLTAGE_OUT] = 3,
 	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
 		PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
 		PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP | PMBUS_HAVE_POUT |
 		PMBUS_HAVE_PIN | PMBUS_HAVE_STATUS_INPUT,
 	.func[1] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_IOUT |
 		PMBUS_HAVE_STATUS_IOUT | PMBUS_HAVE_POUT | PMBUS_HAVE_TEMP,
 	.read_byte_data = mp2856_read_byte_data,
 	.read_word_data = mp2856_read_word_data,
 };

 static int mp2856_probe(struct i2c_client *client)
 {
 	struct pmbus_driver_info *info;
 	struct mp2856_data *data;
 	enum chips chip_id;
 	int ret;

 	data = devm_kzalloc(&client->dev, sizeof(struct mp2856_data),
 			    GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	chip_id = (kernel_ulong_t)i2c_get_match_data(client);

 	memcpy(data->max_phases, mp2856_max_phases[chip_id],
 	       sizeof(data->max_phases));

 	memcpy(&data->info, &mp2856_info, sizeof(*info));
 	info = &data->info;

 	/* Identify multiphase configuration. */
 	ret = mp2856_identify_multiphase_rail1(client, data);
 	if (ret < 0)
 		return ret;

 	if (mp2856_is_rail2_active(client)) {
 		ret = mp2856_identify_multiphase_rail2(client, data);
 		if (ret < 0)
 			return ret;
 	} else {
 		/* rail2 is not active */
 		info->pages = 1;
 	}

 	/* Obtain current sense gain of power stage. */
 	ret = mp2856_current_sense_gain_get(client, data);
 	if (ret)
 		return ret;

 	/* Identify vout format. */
 	ret = mp2856_identify_vout_format(client, data);
 	if (ret)
 		return ret;

 	/* set the device to page 0 */
 	i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);

 	return pmbus_do_probe(client, info);
 }

 static const struct of_device_id __maybe_unused mp2856_of_match[] = {
 	{.compatible = "mps,mp2856", .data = (void *)mp2856},
 	{.compatible = "mps,mp2857", .data = (void *)mp2857},
 	{}
 };
 MODULE_DEVICE_TABLE(of, mp2856_of_match);

 static struct i2c_driver mp2856_driver = {
 	.driver = {
 		.name = "mp2856",
 		.of_match_table = mp2856_of_match,
 	},
 	.probe = mp2856_probe,
 	.id_table = mp2856_id,
 };

 module_i2c_driver(mp2856_driver);

 MODULE_AUTHOR("Peter Yin <peter.yin@quantatw.com>");
 MODULE_DESCRIPTION("PMBus driver for MPS MP2856/MP2857 device");
 MODULE_LICENSE("GPL");
 MODULE_IMPORT_NS(PMBUS);
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Hardware monitoring driver for MPS2856/2857
	* Monolithic Power Systems VR Controllers
	*
	* Copyright (C) 2023 Quanta Computer lnc.
	*/

	#include <linux/err.h>
	#include <linux/i2c.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/pmbus.h>
	#include "pmbus.h"

	/* Vendor specific registers. */
	#define MP2856_MFR_VR_MULTI_CONFIG_R1 0x0d
	#define MP2856_MFR_VR_MULTI_CONFIG_R2 0x1d

	#define MP2856_MUL1_BOOT_SR_R2 0x10
	#define MP2856_VR_ACTIVE BIT(15)

	#define MP2856_MFR_VR_CONFIG2 0x5e
	#define MP2856_VOUT_MODE BIT(11)

	#define MP2856_MFR_VR_CONFIG1 0x68
	#define MP2856_DRMOS_KCS GENMASK(13, 12)

	#define MP2856_MFR_READ_CS1_2_R1 0x82
	#define MP2856_MFR_READ_CS3_4_R1 0x83
	#define MP2856_MFR_READ_CS5_6_R1 0x84
	#define MP2856_MFR_READ_CS7_8_R1 0x85
	#define MP2856_MFR_READ_CS9_10_R1 0x86
	#define MP2856_MFR_READ_CS11_12_R1 0x87

	#define MP2856_MFR_READ_CS1_2_R2 0x85
	#define MP2856_MFR_READ_CS3_4_R2 0x86
	#define MP2856_MFR_READ_CS5_6_R2 0x87

	#define MP2856_MAX_PHASE_RAIL1 8
	#define MP2856_MAX_PHASE_RAIL2 4

	#define MP2857_MAX_PHASE_RAIL1 12
	#define MP2857_MAX_PHASE_RAIL2 4

	#define MP2856_PAGE_NUM 2

	enum chips { mp2856, mp2857 };

	static const int mp2856_max_phases[][MP2856_PAGE_NUM] = {
	[mp2856] = { MP2856_MAX_PHASE_RAIL1, MP2856_MAX_PHASE_RAIL2 },
	[mp2857] = { MP2857_MAX_PHASE_RAIL1, MP2857_MAX_PHASE_RAIL2 },
	};

	static const struct i2c_device_id mp2856_id[] = {
	{"mp2856", mp2856},
	{"mp2857", mp2857},
	{}
	};

	MODULE_DEVICE_TABLE(i2c, mp2856_id);

	struct mp2856_data {
	struct pmbus_driver_info info;
	int vout_format[MP2856_PAGE_NUM];
	int curr_sense_gain[MP2856_PAGE_NUM];
	int max_phases[MP2856_PAGE_NUM];
	};

	#define to_mp2856_data(x) container_of(x, struct mp2856_data, info)

	#define MAX_LIN_MANTISSA (1023 * 1000)
	#define MIN_LIN_MANTISSA (511 * 1000)

	static u16 val2linear11(s64 val)
	{
	s16 exponent = 0, mantissa;
	bool negative = false;

	if (val == 0)
	return 0;

	if (val < 0) {
	negative = true;
	val = -val;
	}

	/* Reduce large mantissa until it fits into 10 bit */
	while (val >= MAX_LIN_MANTISSA && exponent < 15) {
	exponent++;
	val >>= 1;
	}
	/* Increase small mantissa to improve precision */
	while (val < MIN_LIN_MANTISSA && exponent > -15) {
	exponent--;
	val <<= 1;
	}

	/* Convert mantissa from milli-units to units */
	mantissa = clamp_val(DIV_ROUND_CLOSEST_ULL(val, 1000), 0, 0x3ff);

	/* restore sign */
	if (negative)
	mantissa = -mantissa;

	/* Convert to 5 bit exponent, 11 bit mantissa */
	return (mantissa & 0x7ff) \| ((exponent << 11) & 0xf800);
	}

	static int
	mp2856_read_word_helper(struct i2c_client *client, int page, int phase, u8 reg,
	u16 mask)
	{
	int ret = pmbus_read_word_data(client, page, phase, reg);

	return (ret > 0) ? ret & mask : ret;
	}

	static int
	mp2856_read_vout(struct i2c_client client, struct mp2856_data data, int page,
	int phase, u8 reg)
	{
	int ret;

	ret = mp2856_read_word_helper(client, page, phase, reg,
	GENMASK(9, 0));
	if (ret < 0)
	return ret;

	/* convert vout result to direct format */
	ret = (data->vout_format[page] == vid) ?
	((ret + 49) * 5) : ((ret * 1000) >> 8);

	return ret;
	}

	static int
	mp2856_read_phase(struct i2c_client client, struct mp2856_data data,
	int page, int phase, u8 reg)
	{
	int ret;
	int val;

	ret = pmbus_read_word_data(client, page, phase, reg);
	if (ret < 0)
	return ret;

	if (!((phase + 1) % MP2856_PAGE_NUM))
	ret >>= 8;
	ret &= 0xff;

	/*
	* Output value is calculated as: (READ_CSx * 12.5mV - 1.23V) / (Kcs * Rcs)
	*/
	val = (ret * 125) - 12300;

	return val2linear11(val);
	}

	static int
	mp2856_read_phases(struct i2c_client client, struct mp2856_data data,
	int page, int phase)
	{
	int ret;

	if (page == 0) {
	switch (phase) {
	case 0 ... 1:
	ret = mp2856_read_phase(client, data, page, phase,
	MP2856_MFR_READ_CS1_2_R1);
	break;
	case 2 ... 3:
	ret = mp2856_read_phase(client, data, page, phase,
	MP2856_MFR_READ_CS3_4_R1);
	break;
	case 4 ... 5:
	ret = mp2856_read_phase(client, data, page, phase,
	MP2856_MFR_READ_CS5_6_R1);
	break;
	case 6 ... 7:
	ret = mp2856_read_phase(client, data, page, phase,
	MP2856_MFR_READ_CS7_8_R1);
	break;
	default:
	return -ENODATA;
	}
	} else {
	switch (phase) {
	case 0 ... 1:
	ret = mp2856_read_phase(client, data, page, phase,
	MP2856_MFR_READ_CS1_2_R2);
	break;
	case 2 ... 3:
	ret = mp2856_read_phase(client, data, page, phase,
	MP2856_MFR_READ_CS1_2_R2);
	break;
	default:
	return -ENODATA;
	}
	}
	return ret;
	}

	static int
	mp2856_read_word_data(struct i2c_client *client, int page,
	int phase, int reg)
	{
	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
	struct mp2856_data *data = to_mp2856_data(info);
	int ret;

	switch (reg) {
	case PMBUS_READ_VOUT:
	ret = mp2856_read_vout(client, data, page, phase, reg);
	break;
	case PMBUS_READ_IOUT:
	if (phase != 0xff)
	ret = mp2856_read_phases(client, data, page, phase);
	else
	ret = pmbus_read_word_data(client, page, phase, reg);
	break;
	default:
	return -ENODATA;
	}

	return ret;
	}

	static int
	mp2856_read_byte_data(struct i2c_client *client, int page, int reg)
	{
	switch (reg) {
	case PMBUS_VOUT_MODE:
	/* Enforce VOUT direct format. */
	return PB_VOUT_MODE_DIRECT;
	default:
	return -ENODATA;
	}
	}

	static int
	mp2856_identify_multiphase(struct i2c_client *client, u8 reg, u8 max_phase,
	u16 mask)
	{
	int ret;

	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
	if (ret < 0)
	return ret;

	ret = i2c_smbus_read_word_data(client, reg);
	if (ret < 0)
	return ret;

	ret &= mask;
	return (ret >= max_phase) ? max_phase : ret;
	}

	static int
	mp2856_identify_multiphase_rail1(struct i2c_client *client,
	struct mp2856_data *data)
	{
	int ret, i;

	ret = mp2856_identify_multiphase(client, MP2856_MFR_VR_MULTI_CONFIG_R1,
	MP2856_MAX_PHASE_RAIL1, GENMASK(3, 0));
	if (ret < 0)
	return ret;

	data->info.phases[0] = (ret > data->max_phases[0]) ?
	data->max_phases[0] : ret;

	for (i = 0 ; i < data->info.phases[0]; i++)
	data->info.pfunc[i] \|= PMBUS_HAVE_IOUT;

	return 0;
	}

	static int
	mp2856_identify_multiphase_rail2(struct i2c_client *client,
	struct mp2856_data *data)
	{
	int ret, i;

	ret = mp2856_identify_multiphase(client, MP2856_MFR_VR_MULTI_CONFIG_R2,
	MP2856_MAX_PHASE_RAIL2, GENMASK(2, 0));
	if (ret < 0)
	return ret;

	data->info.phases[1] = (ret > data->max_phases[1]) ?
	data->max_phases[1] : ret;

	for (i = 0 ; i < data->info.phases[0]; i++)
	data->info.pfunc[i] \|= PMBUS_HAVE_IOUT;

	return 0;
	}

	static int
	mp2856_current_sense_gain_get(struct i2c_client *client,
	struct mp2856_data *data)
	{
	int i, ret;

	/*
	* Obtain DrMOS current sense gain of power stage from the register
	* MP2856_MFR_VR_CONFIG1, bits 13-12. The value is selected as below:
	* 00b - 5µA/A, 01b - 8.5µA/A, 10b - 9.7µA/A, 11b - 10µA/A. Other
	* values are invalid.
	*/
	for (i = 0 ; i < data->info.pages; i++) {
	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
	if (ret < 0)
	return ret;
	ret = i2c_smbus_read_word_data(client,
	MP2856_MFR_VR_CONFIG1);
	if (ret < 0)
	return ret;

	switch ((ret & MP2856_DRMOS_KCS) >> 12) {
	case 0:
	data->curr_sense_gain[i] = 50;
	break;
	case 1:
	data->curr_sense_gain[i] = 85;
	break;
	case 2:
	data->curr_sense_gain[i] = 97;
	break;
	default:
	data->curr_sense_gain[i] = 100;
	break;
	}
	}
	return 0;
	}

	static int
	mp2856_identify_vout_format(struct i2c_client *client,
	struct mp2856_data *data)
	{
	int i, ret;

	for (i = 0; i < data->info.pages; i++) {
	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
	if (ret < 0)
	return ret;

	ret = i2c_smbus_read_word_data(client, MP2856_MFR_VR_CONFIG2);
	if (ret < 0)
	return ret;

	data->vout_format[i] = (ret & MP2856_VOUT_MODE) ? linear : vid;
	}
	return 0;
	}

	static bool
	mp2856_is_rail2_active(struct i2c_client *client)
	{
	int ret;

	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
	if (ret < 0)
	return true;

	ret = i2c_smbus_read_word_data(client, MP2856_MUL1_BOOT_SR_R2);
	if (ret < 0)
	return true;

	return (ret & MP2856_VR_ACTIVE) ? true : false;
	}

	static struct pmbus_driver_info mp2856_info = {
	.pages = MP2856_PAGE_NUM,
	.format[PSC_VOLTAGE_IN] = linear,
	.format[PSC_VOLTAGE_OUT] = direct,
	.format[PSC_TEMPERATURE] = linear,
	.format[PSC_CURRENT_IN] = linear,
	.format[PSC_CURRENT_OUT] = linear,
	.format[PSC_POWER] = linear,
	.m[PSC_VOLTAGE_OUT] = 1,
	.R[PSC_VOLTAGE_OUT] = 3,
	.func[0] = PMBUS_HAVE_VIN \| PMBUS_HAVE_VOUT \| PMBUS_HAVE_STATUS_VOUT \|
	PMBUS_HAVE_IIN \| PMBUS_HAVE_IOUT \| PMBUS_HAVE_STATUS_IOUT \|
	PMBUS_HAVE_TEMP \| PMBUS_HAVE_STATUS_TEMP \| PMBUS_HAVE_POUT \|
	PMBUS_HAVE_PIN \| PMBUS_HAVE_STATUS_INPUT,
	.func[1] = PMBUS_HAVE_VOUT \| PMBUS_HAVE_STATUS_VOUT \| PMBUS_HAVE_IOUT \|
	PMBUS_HAVE_STATUS_IOUT \| PMBUS_HAVE_POUT \| PMBUS_HAVE_TEMP,
	.read_byte_data = mp2856_read_byte_data,
	.read_word_data = mp2856_read_word_data,
	};

	static int mp2856_probe(struct i2c_client *client)
	{
	struct pmbus_driver_info *info;
	struct mp2856_data *data;
	enum chips chip_id;
	int ret;

	data = devm_kzalloc(&client->dev, sizeof(struct mp2856_data),
	GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	chip_id = (kernel_ulong_t)i2c_get_match_data(client);

	memcpy(data->max_phases, mp2856_max_phases[chip_id],
	sizeof(data->max_phases));

	memcpy(&data->info, &mp2856_info, sizeof(*info));
	info = &data->info;

	/* Identify multiphase configuration. */
	ret = mp2856_identify_multiphase_rail1(client, data);
	if (ret < 0)
	return ret;

	if (mp2856_is_rail2_active(client)) {
	ret = mp2856_identify_multiphase_rail2(client, data);
	if (ret < 0)
	return ret;
	} else {
	/* rail2 is not active */
	info->pages = 1;
	}

	/* Obtain current sense gain of power stage. */
	ret = mp2856_current_sense_gain_get(client, data);
	if (ret)
	return ret;

	/* Identify vout format. */
	ret = mp2856_identify_vout_format(client, data);
	if (ret)
	return ret;

	/* set the device to page 0 */
	i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);

	return pmbus_do_probe(client, info);
	}

	static const struct of_device_id __maybe_unused mp2856_of_match[] = {
	{.compatible = "mps,mp2856", .data = (void *)mp2856},
	{.compatible = "mps,mp2857", .data = (void *)mp2857},
	{}
	};
	MODULE_DEVICE_TABLE(of, mp2856_of_match);

	static struct i2c_driver mp2856_driver = {
	.driver = {
	.name = "mp2856",
	.of_match_table = mp2856_of_match,
	},
	.probe = mp2856_probe,
	.id_table = mp2856_id,
	};

	module_i2c_driver(mp2856_driver);

	MODULE_AUTHOR("Peter Yin <peter.yin@quantatw.com>");
	MODULE_DESCRIPTION("PMBus driver for MPS MP2856/MP2857 device");
	MODULE_LICENSE("GPL");
	MODULE_IMPORT_NS(PMBUS);