linux/drivers/hwmon/pmbus/mp2888.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Hardware monitoring driver for MPS Multi-phase Digital VR Controllers
 *
 * Copyright (C) 2020 Nvidia Technologies Ltd.
 */

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

/* Vendor specific registers. */
#define MP2888_MFR_SYS_CONFIG	0x44
#define MP2888_MFR_READ_CS1_2	0x73
#define MP2888_MFR_READ_CS3_4	0x74
#define MP2888_MFR_READ_CS5_6	0x75
#define MP2888_MFR_READ_CS7_8	0x76
#define MP2888_MFR_READ_CS9_10	0x77
#define MP2888_MFR_VR_CONFIG1	0xe1

#define MP2888_TOTAL_CURRENT_RESOLUTION	BIT(3)
#define MP2888_PHASE_CURRENT_RESOLUTION	BIT(4)
#define MP2888_DRMOS_KCS		GENMASK(2, 0)
#define MP2888_TEMP_UNIT		10
#define MP2888_MAX_PHASE		10

struct mp2888_data {
	struct pmbus_driver_info info;
	int total_curr_resolution;
	int phase_curr_resolution;
	int curr_sense_gain;
};

#define to_mp2888_data(x)  container_of(x, struct mp2888_data, info)

static int mp2888_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
mp2888_current_sense_gain_and_resolution_get(struct i2c_client *client, struct mp2888_data *data)
{
	int ret;

	/*
	 * Obtain DrMOS current sense gain of power stage from the register
	 * , bits 0-2. The value is selected as below:
	 * 00b - 5µA/A, 01b - 8.5µA/A, 10b - 9.7µA/A, 11b - 10µA/A. Other
	 * values are reserved.
	 */
	ret = i2c_smbus_read_word_data(client, MP2888_MFR_SYS_CONFIG);
	if (ret < 0)
		return ret;

	switch (ret & MP2888_DRMOS_KCS) {
	case 0:
		data->curr_sense_gain = 85;
		break;
	case 1:
		data->curr_sense_gain = 97;
		break;
	case 2:
		data->curr_sense_gain = 100;
		break;
	case 3:
		data->curr_sense_gain = 50;
		break;
	default:
		return -EINVAL;
	}

	/*
	 * Obtain resolution selector for total and phase current report and protection.
	 * 0: original resolution; 1: half resolution (in such case phase current value should
	 * be doubled.
	 */
	data->total_curr_resolution = (ret & MP2888_TOTAL_CURRENT_RESOLUTION) >> 3;
	data->phase_curr_resolution = (ret & MP2888_PHASE_CURRENT_RESOLUTION) >> 4;

	return 0;
}

static int
mp2888_read_phase(struct i2c_client *client, struct mp2888_data *data, int page, int phase, u8 reg)
{
	int ret;

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

	if (!((phase + 1) % 2))
		ret >>= 8;
	ret &= 0xff;

	/*
	 * Output value is calculated as: (READ_CSx / 80 – 1.23) / (Kcs * Rcs)
	 * where:
	 * - Kcs is the DrMOS current sense gain of power stage, which is obtained from the
	 *   register MP2888_MFR_VR_CONFIG1, bits 13-12 with the following selection of DrMOS
	 *   (data->curr_sense_gain):
	 *   00b - 5µA/A, 01b - 8.5µA/A, 10b - 9.7µA/A, 11b - 10µA/A.
	 * - Rcs is the internal phase current sense resistor. This parameter depends on hardware
	 *   assembly. By default it is set to 1kΩ. In case of different assembly, user should
	 *   scale this parameter by dividing it by Rcs.
	 * If phase current resolution bit is set to 1, READ_CSx value should be doubled.
	 * Note, that current phase sensing, providing by the device is not accurate. This is
	 * because sampling of current occurrence of bit weight has a big deviation, especially for
	 * light load.
	 */
	ret = DIV_ROUND_CLOSEST(ret * 100 - 9800, data->curr_sense_gain);
	ret = (data->phase_curr_resolution) ? ret * 2 : ret;
	/* Scale according to total current resolution. */
	ret = (data->total_curr_resolution) ? ret * 8 : ret * 4;
	return ret;
}

static int
mp2888_read_phases(struct i2c_client *client, struct mp2888_data *data, int page, int phase)
{
	int ret;

	switch (phase) {
	case 0 ... 1:
		ret = mp2888_read_phase(client, data, page, phase, MP2888_MFR_READ_CS1_2);
		break;
	case 2 ... 3:
		ret = mp2888_read_phase(client, data, page, phase, MP2888_MFR_READ_CS3_4);
		break;
	case 4 ... 5:
		ret = mp2888_read_phase(client, data, page, phase, MP2888_MFR_READ_CS5_6);
		break;
	case 6 ... 7:
		ret = mp2888_read_phase(client, data, page, phase, MP2888_MFR_READ_CS7_8);
		break;
	case 8 ... 9:
		ret = mp2888_read_phase(client, data, page, phase, MP2888_MFR_READ_CS9_10);
		break;
	default:
		return -ENODATA;
	}
	return ret;
}

static int mp2888_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 mp2888_data *data = to_mp2888_data(info);
	int ret;

	switch (reg) {
	case PMBUS_READ_VIN:
		ret = pmbus_read_word_data(client, page, phase, reg);
		if (ret <= 0)
			return ret;

		/*
		 * READ_VIN requires fixup to scale it to linear11 format. Register data format
		 * provides 10 bits for mantissa and 6 bits for exponent. Bits 15:10 are set with
		 * the fixed value 111011b.
		 */
		ret = (ret & GENMASK(9, 0)) | ((ret & GENMASK(31, 10)) << 1);
		break;
	case PMBUS_OT_WARN_LIMIT:
		ret = pmbus_read_word_data(client, page, phase, reg);
		if (ret < 0)
			return ret;
		/*
		 * Chip reports limits in degrees C, but the actual temperature in 10th of
		 * degrees C - scaling is needed to match both.
		 */
		ret *= MP2888_TEMP_UNIT;
		break;
	case PMBUS_READ_IOUT:
		if (phase != 0xff)
			return mp2888_read_phases(client, data, page, phase);

		ret = pmbus_read_word_data(client, page, phase, reg);
		if (ret < 0)
			return ret;
		/*
		 * READ_IOUT register has unused bits 15:12 with fixed value 1110b. Clear these
		 * bits and scale with total current resolution. Data is provided in direct format.
		 */
		ret &= GENMASK(11, 0);
		ret = data->total_curr_resolution ? ret * 2 : ret;
		break;
	case PMBUS_IOUT_OC_WARN_LIMIT:
		ret = pmbus_read_word_data(client, page, phase, reg);
		if (ret < 0)
			return ret;
		ret &= GENMASK(9, 0);
		/*
		 * Chip reports limits with resolution 1A or 2A, if total current resolution bit is
		 * set 1. Actual current is reported with 0.25A or respectively 0.5A resolution.
		 * Scaling is needed to match both.
		 */
		ret = data->total_curr_resolution ? ret * 8 : ret * 4;
		break;
	case PMBUS_READ_POUT:
	case PMBUS_READ_PIN:
		ret = pmbus_read_word_data(client, page, phase, reg);
		if (ret < 0)
			return ret;
		ret = data->total_curr_resolution ? ret * 2 : ret;
		break;
	case PMBUS_POUT_OP_WARN_LIMIT:
		ret = pmbus_read_word_data(client, page, phase, reg);
		if (ret < 0)
			return ret;
		/*
		 * Chip reports limits with resolution 1W or 2W, if total current resolution bit is
		 * set 1. Actual power is reported with 0.5W or 1W respectively resolution. Scaling
		 * is needed to match both.
		 */
		ret = data->total_curr_resolution ? ret * 4 : ret * 2;
		break;
	/*
	 * The below registers are not implemented by device or implemented not according to the
	 * spec. Skip all of them to avoid exposing non-relevant inputs to sysfs.
	 */
	case PMBUS_OT_FAULT_LIMIT:
	case PMBUS_UT_WARN_LIMIT:
	case PMBUS_UT_FAULT_LIMIT:
	case PMBUS_VIN_UV_FAULT_LIMIT:
	case PMBUS_VOUT_UV_WARN_LIMIT:
	case PMBUS_VOUT_OV_WARN_LIMIT:
	case PMBUS_VOUT_UV_FAULT_LIMIT:
	case PMBUS_VOUT_OV_FAULT_LIMIT:
	case PMBUS_VIN_OV_WARN_LIMIT:
	case PMBUS_IOUT_OC_LV_FAULT_LIMIT:
	case PMBUS_IOUT_OC_FAULT_LIMIT:
	case PMBUS_POUT_MAX:
	case PMBUS_IOUT_UC_FAULT_LIMIT:
	case PMBUS_POUT_OP_FAULT_LIMIT:
	case PMBUS_PIN_OP_WARN_LIMIT:
	case PMBUS_MFR_VIN_MIN:
	case PMBUS_MFR_VOUT_MIN:
	case PMBUS_MFR_VIN_MAX:
	case PMBUS_MFR_VOUT_MAX:
	case PMBUS_MFR_IIN_MAX:
	case PMBUS_MFR_IOUT_MAX:
	case PMBUS_MFR_PIN_MAX:
	case PMBUS_MFR_POUT_MAX:
	case PMBUS_MFR_MAX_TEMP_1:
		return -ENXIO;
	default:
		return -ENODATA;
	}

	return ret;
}

static int mp2888_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 mp2888_data *data = to_mp2888_data(info);

	switch (reg) {
	case PMBUS_OT_WARN_LIMIT:
		word = DIV_ROUND_CLOSEST(word, MP2888_TEMP_UNIT);
		/* Drop unused bits 15:8. */
		word = clamp_val(word, 0, GENMASK(7, 0));
		break;
	case PMBUS_IOUT_OC_WARN_LIMIT:
		/* Fix limit according to total curent resolution. */
		word = data->total_curr_resolution ? DIV_ROUND_CLOSEST(word, 8) :
		       DIV_ROUND_CLOSEST(word, 4);
		/* Drop unused bits 15:10. */
		word = clamp_val(word, 0, GENMASK(9, 0));
		break;
	case PMBUS_POUT_OP_WARN_LIMIT:
		/* Fix limit according to total curent resolution. */
		word = data->total_curr_resolution ? DIV_ROUND_CLOSEST(word, 4) :
		       DIV_ROUND_CLOSEST(word, 2);
		/* Drop unused bits 15:10. */
		word = clamp_val(word, 0, GENMASK(9, 0));
		break;
	default:
		return -ENODATA;
	}
	return pmbus_write_word_data(client, page, reg, word);
}

static int
mp2888_identify_multiphase(struct i2c_client *client, struct mp2888_data *data,
			   struct pmbus_driver_info *info)
{
	int ret;

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

	/* Identify multiphase number - could be from 1 to 10. */
	ret = i2c_smbus_read_word_data(client, MP2888_MFR_VR_CONFIG1);
	if (ret <= 0)
		return ret;

	info->phases[0] = ret & GENMASK(3, 0);

	/*
	 * The device provides a total of 10 PWM pins, and can be configured to different phase
	 * count applications for rail.
	 */
	if (info->phases[0] > MP2888_MAX_PHASE)
		return -EINVAL;

	return 0;
}

static struct pmbus_driver_info mp2888_info = {
	.pages = 1,
	.format[PSC_VOLTAGE_IN] = linear,
	.format[PSC_VOLTAGE_OUT] = direct,
	.format[PSC_TEMPERATURE] = direct,
	.format[PSC_CURRENT_IN] = linear,
	.format[PSC_CURRENT_OUT] = direct,
	.format[PSC_POWER] = direct,
	.m[PSC_TEMPERATURE] = 1,
	.R[PSC_TEMPERATURE] = 1,
	.m[PSC_VOLTAGE_OUT] = 1,
	.R[PSC_VOLTAGE_OUT] = 3,
	.m[PSC_CURRENT_OUT] = 4,
	.m[PSC_POWER] = 1,
	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_IOUT |
		   PMBUS_HAVE_STATUS_IOUT | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP |
		   PMBUS_HAVE_POUT | PMBUS_HAVE_PIN | PMBUS_HAVE_STATUS_INPUT |
		   PMBUS_PHASE_VIRTUAL,
	.pfunc[0] = PMBUS_HAVE_IOUT,
	.pfunc[1] = PMBUS_HAVE_IOUT,
	.pfunc[2] = PMBUS_HAVE_IOUT,
	.pfunc[3] = PMBUS_HAVE_IOUT,
	.pfunc[4] = PMBUS_HAVE_IOUT,
	.pfunc[5] = PMBUS_HAVE_IOUT,
	.pfunc[6] = PMBUS_HAVE_IOUT,
	.pfunc[7] = PMBUS_HAVE_IOUT,
	.pfunc[8] = PMBUS_HAVE_IOUT,
	.pfunc[9] = PMBUS_HAVE_IOUT,
	.read_byte_data = mp2888_read_byte_data,
	.read_word_data = mp2888_read_word_data,
	.write_word_data = mp2888_write_word_data,
};

static int mp2888_probe(struct i2c_client *client)
{
	struct pmbus_driver_info *info;
	struct mp2888_data *data;
	int ret;

	data = devm_kzalloc(&client->dev, sizeof(struct mp2888_data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	memcpy(&data->info, &mp2888_info, sizeof(*info));
	info = &data->info;

	/* Identify multiphase configuration. */
	ret = mp2888_identify_multiphase(client, data, info);
	if (ret)
		return ret;

	/* Obtain current sense gain of power stage and current resolution. */
	ret = mp2888_current_sense_gain_and_resolution_get(client, data);
	if (ret)
		return ret;

	return pmbus_do_probe(client, info);
}

static const struct i2c_device_id mp2888_id[] = {
	{"mp2888", 0},
	{}
};

MODULE_DEVICE_TABLE(i2c, mp2888_id);

static const struct of_device_id __maybe_unused mp2888_of_match[] = {
	{.compatible = "mps,mp2888"},
	{}
};
MODULE_DEVICE_TABLE(of, mp2888_of_match);

static struct i2c_driver mp2888_driver = {
	.driver = {
		.name = "mp2888",
		.of_match_table = of_match_ptr(mp2888_of_match),
	},
	.probe_new = mp2888_probe,
	.id_table = mp2888_id,
};

module_i2c_driver(mp2888_driver);

MODULE_AUTHOR("Vadim Pasternak <vadimp@nvidia.com>");
MODULE_DESCRIPTION("PMBus driver for MPS MP2888 device");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS(PMBUS);