drivers/regulator/mp8859.c - pub/scm/linux/kernel/git/mkl/linux-can - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 //
 // Copyright (c) 2019 five technologies GmbH
 // Author: Markus Reichl <m.reichl@fivetechno.de>

 #include <linux/module.h>
 #include <linux/i2c.h>
 #include <linux/of.h>
 #include <linux/regulator/driver.h>
 #include <linux/regmap.h>


 #define VOL_MIN_IDX			0x00
 #define VOL_MAX_IDX			0x7ff

 /* Register definitions */
 #define MP8859_VOUT_L_REG		0    //3 lo Bits
 #define MP8859_VOUT_H_REG		1    //8 hi Bits
 #define MP8859_VOUT_GO_REG		2
 #define MP8859_IOUT_LIM_REG		3
 #define MP8859_CTL1_REG			4
 #define MP8859_CTL2_REG			5
 #define MP8859_RESERVED1_REG		6
 #define MP8859_RESERVED2_REG		7
 #define MP8859_RESERVED3_REG		8
 #define MP8859_STATUS_REG		9
 #define MP8859_INTERRUPT_REG		0x0A
 #define MP8859_MASK_REG			0x0B
 #define MP8859_ID1_REG			0x0C
 #define MP8859_MFR_ID_REG		0x27
 #define MP8859_DEV_ID_REG		0x28
 #define MP8859_IC_REV_REG		0x29

 #define MP8859_MAX_REG			0x29

 #define MP8859_GO_BIT			0x01

 #define MP8859_IOUT_LIM_MASK		0x7f

 #define MP8859_ENABLE_MASK		0x80
 #define MP8859_DISCHG_EN_MASK		0x10
 #define MP8859_MODE_MASK		0x08

 #define MP8859_PG_MASK			0x80
 #define MP8859_OTP_MASK			0x40
 #define MP8859_OTW_MASK			0x20
 #define MP8859_CC_CV_MASK		0x10

 static int mp8859_set_voltage_sel(struct regulator_dev *rdev, unsigned int sel)
 {
 	int ret;

 	ret = regmap_write(rdev->regmap, MP8859_VOUT_L_REG, sel & 0x7);

 	if (ret)
 		return ret;
 	ret = regmap_write(rdev->regmap, MP8859_VOUT_H_REG, sel >> 3);

 	if (ret)
 		return ret;
 	ret = regmap_update_bits(rdev->regmap, MP8859_VOUT_GO_REG,
 					MP8859_GO_BIT, 1);
 	return ret;
 }

 static int mp8859_get_voltage_sel(struct regulator_dev *rdev)
 {
 	unsigned int val_tmp;
 	unsigned int val;
 	int ret;

 	ret = regmap_read(rdev->regmap, MP8859_VOUT_H_REG, &val_tmp);

 	if (ret)
 		return ret;
 	val = val_tmp << 3;

 	ret = regmap_read(rdev->regmap, MP8859_VOUT_L_REG, &val_tmp);

 	if (ret)
 		return ret;
 	val |= val_tmp & 0x07;
 	return val;
 }

 static int mp8859_set_voltage_time_sel(struct regulator_dev *rdev,
 				       unsigned int from, unsigned int to)
 {
 	int change;

 	/* The voltage ramps at 1mV/uS, selectors are 10mV */
 	if (from > to)
 		change = from - to;
 	else
 		change = to - from;

 	return change * 10 * 1000;
 }

 static unsigned int mp8859_get_mode(struct regulator_dev *rdev)
 {
 	unsigned int val;
 	int ret;

 	ret = regmap_read(rdev->regmap, MP8859_CTL1_REG, &val);
 	if (ret != 0) {
 		dev_err(&rdev->dev, "Failed to read mode: %d\n", ret);
 		return 0;
 	}

 	if (val & MP8859_MODE_MASK)
 		return REGULATOR_MODE_FAST;
 	else
 		return REGULATOR_MODE_NORMAL;
 }

 static int mp8859_set_mode(struct regulator_dev *rdev, unsigned int mode)
 {
 	unsigned int val;

 	switch (mode) {
 	case REGULATOR_MODE_FAST:
 		val = MP8859_MODE_MASK;
 		break;
 	case REGULATOR_MODE_NORMAL:
 		val = 0;
 		break;
 	default:
 		return -EINVAL;
 	}

 	return regmap_update_bits(rdev->regmap, MP8859_CTL1_REG,
 				  MP8859_MODE_MASK, val);
 }

 static int mp8859_set_current_limit(struct regulator_dev *rdev,
 				    int min_uA, int max_uA)
 {
 	unsigned int cur_val, new_val;
 	int ret, i;

 	/* Steps of 50mA */
 	new_val = max_uA / 50000;
 	if (new_val > MP8859_IOUT_LIM_MASK)
 		return -EINVAL;
 	if (new_val == 0)
 		return -EINVAL;

 	/*
 	 * If the regulator is limiting then ramp gradually as per
 	 * datasheet, otherwise just set the value directly.
 	 */
 	ret = regmap_read(rdev->regmap, MP8859_STATUS_REG, &cur_val);
 	if (ret != 0)
 		return ret;
 	if (!(cur_val & MP8859_CC_CV_MASK)) {
 		return regmap_update_bits(rdev->regmap, MP8859_IOUT_LIM_REG,
 					  MP8859_IOUT_LIM_MASK, new_val);
 	}

 	ret = regmap_read(rdev->regmap, MP8859_IOUT_LIM_REG, &cur_val);
 	if (ret != 0)
 		return ret;

 	if (cur_val >= new_val) {
 		for (i = cur_val; i >= new_val; i--) {
 			ret = regmap_update_bits(rdev->regmap,
 						 MP8859_IOUT_LIM_REG,
 						 MP8859_IOUT_LIM_MASK,
 						 cur_val - i);
 			if (ret != 0)
 				return ret;
 		}
 	} else {
 		for (i = cur_val; i <= new_val; i++) {
 			ret = regmap_update_bits(rdev->regmap,
 						 MP8859_IOUT_LIM_REG,
 						 MP8859_IOUT_LIM_MASK,
 						 cur_val + i);
 			if (ret != 0)
 				return ret;
 		}
 	}

 	return 0;
 }

 static int mp8859_get_status(struct regulator_dev *rdev)
 {
 	unsigned int val;
 	int ret;

 	/* Output status is only meaingful when enabled */
 	ret = regmap_read(rdev->regmap, MP8859_CTL1_REG, &val);
 	if (ret != 0)
 		return ret;
 	if (!(val & MP8859_ENABLE_MASK))
 		return REGULATOR_STATUS_UNDEFINED;

 	ret = regmap_read(rdev->regmap, MP8859_STATUS_REG, &val);
 	if (ret != 0)
 		return ret;

 	if (val & MP8859_PG_MASK)
 		return REGULATOR_STATUS_ON;
 	else
 		return REGULATOR_STATUS_ERROR;
 }

 static int mp8859_get_error_flags(struct regulator_dev *rdev,
 				  unsigned int *flags)
 {
 	unsigned int status, enabled;
 	int ret;

 	*flags = 0;

 	/* Output status is only meaingful when enabled */
 	ret = regmap_read(rdev->regmap, MP8859_CTL1_REG, &enabled);
 	if (ret != 0)
 		return ret;
 	enabled &= MP8859_ENABLE_MASK;

 	ret = regmap_read(rdev->regmap, MP8859_STATUS_REG, &status);
 	if (ret != 0)
 		return ret;

 	if (enabled && !(status & MP8859_PG_MASK))
 		status |= REGULATOR_ERROR_FAIL;
 	if (status & MP8859_OTP_MASK)
 		status |= REGULATOR_ERROR_OVER_TEMP;
 	if (status & MP8859_OTW_MASK)
 		status |= REGULATOR_ERROR_OVER_TEMP_WARN;
 	if (status & MP8859_CC_CV_MASK)
 		status |= REGULATOR_ERROR_OVER_CURRENT;

 	return 0;
 }

 static const struct linear_range mp8859_dcdc_ranges[] = {
 	REGULATOR_LINEAR_RANGE(0, VOL_MIN_IDX, VOL_MAX_IDX, 10000),
 };

 static bool mp8859_readable(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case MP8859_VOUT_L_REG:
 	case MP8859_VOUT_H_REG:
 	case MP8859_VOUT_GO_REG:
 	case MP8859_IOUT_LIM_REG:
 	case MP8859_CTL1_REG:
 	case MP8859_CTL2_REG:
 	case MP8859_STATUS_REG:
 	case MP8859_INTERRUPT_REG:
 	case MP8859_MASK_REG:
 	case MP8859_ID1_REG:
 	case MP8859_MFR_ID_REG:
 	case MP8859_DEV_ID_REG:
 	case MP8859_IC_REV_REG:
 		return true;
 	default:
 		return false;
 	}
 }

 static bool mp8859_volatile(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case MP8859_VOUT_GO_REG:
 	case MP8859_STATUS_REG:
 	case MP8859_INTERRUPT_REG:
 		return true;
 	default:
 		return false;
 	}
 }

 static const struct regmap_config mp8859_regmap = {
 	.reg_bits = 8,
 	.val_bits = 8,
 	.max_register = MP8859_MAX_REG,
 	.cache_type = REGCACHE_MAPLE,
 	.readable_reg = mp8859_readable,
 	.volatile_reg = mp8859_volatile,
 };

 static const struct regulator_ops mp8859_ops = {
 	.set_voltage_sel = mp8859_set_voltage_sel,
 	.get_voltage_sel = mp8859_get_voltage_sel,
 	.list_voltage = regulator_list_voltage_linear_range,
 	.set_voltage_time_sel = mp8859_set_voltage_time_sel,
 	.enable = regulator_enable_regmap,
 	.disable = regulator_disable_regmap,
 	.is_enabled = regulator_is_enabled_regmap,
 	.set_mode = mp8859_set_mode,
 	.get_mode = mp8859_get_mode,
 	.set_active_discharge = regulator_set_active_discharge_regmap,
 	.set_current_limit = mp8859_set_current_limit,
 	.get_status = mp8859_get_status,
 	.get_error_flags = mp8859_get_error_flags,
 };

 static const struct regulator_desc mp8859_regulators[] = {
 	{
 		.id = 0,
 		.type = REGULATOR_VOLTAGE,
 		.name = "mp8859_dcdc",
 		.supply_name = "vin",
 		.of_match = of_match_ptr("mp8859_dcdc"),
 		.n_voltages = VOL_MAX_IDX + 1,
 		.linear_ranges = mp8859_dcdc_ranges,
 		.n_linear_ranges = 1,
 		.enable_reg = MP8859_CTL1_REG,
 		.enable_mask = MP8859_ENABLE_MASK,
 		.enable_val = MP8859_ENABLE_MASK,
 		.active_discharge_reg = MP8859_CTL1_REG,
 		.active_discharge_on = MP8859_DISCHG_EN_MASK,
 		.active_discharge_mask = MP8859_DISCHG_EN_MASK,
 		.ops = &mp8859_ops,
 		.owner = THIS_MODULE,
 	},
 };

 static int mp8859_i2c_probe(struct i2c_client *i2c)
 {
 	int ret;
 	struct regulator_config config = {.dev = &i2c->dev};
 	struct regmap *regmap = devm_regmap_init_i2c(i2c, &mp8859_regmap);
 	struct regulator_dev *rdev;
 	unsigned int val, rev;

 	if (IS_ERR(regmap)) {
 		ret = PTR_ERR(regmap);
 		dev_err(&i2c->dev, "regmap init failed: %d\n", ret);
 		return ret;
 	}

 	ret = regmap_read(regmap, MP8859_MFR_ID_REG, &val);
 	if (ret != 0) {
 		dev_err(&i2c->dev, "Failed to read manufacturer ID: %d\n", ret);
 		return ret;
 	}
 	if (val != 0x9) {
 		dev_err(&i2c->dev, "Manufacturer ID %x != 9\n", val);
 		return -EINVAL;
 	}

 	ret = regmap_read(regmap, MP8859_DEV_ID_REG, &val);
 	if (ret != 0) {
 		dev_err(&i2c->dev, "Failed to read device ID: %d\n", ret);
 		return ret;
 	}
 	if (val != 0x58) {
 		dev_err(&i2c->dev, "Manufacturer ID %x != 0x58\n", val);
 		return -EINVAL;
 	}

 	ret = regmap_read(regmap, MP8859_IC_REV_REG, &rev);
 	if (ret != 0) {
 		dev_err(&i2c->dev, "Failed to read device revision: %d\n", ret);
 		return ret;
 	}
 	ret = regmap_read(regmap, MP8859_ID1_REG, &val);
 	if (ret != 0) {
 		dev_err(&i2c->dev, "Failed to read device ID1: %d\n", ret);
 		return ret;
 	}
 	dev_info(&i2c->dev, "MP8859-%04d revision %d\n", val, rev);

 	rdev = devm_regulator_register(&i2c->dev, &mp8859_regulators[0],
 					&config);

 	if (IS_ERR(rdev)) {
 		ret = PTR_ERR(rdev);
 		dev_err(&i2c->dev, "failed to register %s: %d\n",
 			mp8859_regulators[0].name, ret);
 		return ret;
 	}
 	return 0;
 }

 static const struct of_device_id mp8859_dt_id[] __maybe_unused = {
 	{.compatible =  "mps,mp8859"},
 	{},
 };
 MODULE_DEVICE_TABLE(of, mp8859_dt_id);

 static const struct i2c_device_id mp8859_i2c_id[] = {
 	{ "mp8859", },
 	{  },
 };
 MODULE_DEVICE_TABLE(i2c, mp8859_i2c_id);

 static struct i2c_driver mp8859_regulator_driver = {
 	.driver = {
 		.name = "mp8859",
 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 		.of_match_table = of_match_ptr(mp8859_dt_id),
 	},
 	.probe = mp8859_i2c_probe,
 	.id_table = mp8859_i2c_id,
 };

 module_i2c_driver(mp8859_regulator_driver);

 MODULE_DESCRIPTION("Monolithic Power Systems MP8859 voltage regulator driver");
 MODULE_AUTHOR("Markus Reichl <m.reichl@fivetechno.de>");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	//
	// Copyright (c) 2019 five technologies GmbH
	// Author: Markus Reichl <m.reichl@fivetechno.de>

	#include <linux/module.h>
	#include <linux/i2c.h>
	#include <linux/of.h>
	#include <linux/regulator/driver.h>
	#include <linux/regmap.h>


	#define VOL_MIN_IDX 0x00
	#define VOL_MAX_IDX 0x7ff

	/* Register definitions */
	#define MP8859_VOUT_L_REG 0 //3 lo Bits
	#define MP8859_VOUT_H_REG 1 //8 hi Bits
	#define MP8859_VOUT_GO_REG 2
	#define MP8859_IOUT_LIM_REG 3
	#define MP8859_CTL1_REG 4
	#define MP8859_CTL2_REG 5
	#define MP8859_RESERVED1_REG 6
	#define MP8859_RESERVED2_REG 7
	#define MP8859_RESERVED3_REG 8
	#define MP8859_STATUS_REG 9
	#define MP8859_INTERRUPT_REG 0x0A
	#define MP8859_MASK_REG 0x0B
	#define MP8859_ID1_REG 0x0C
	#define MP8859_MFR_ID_REG 0x27
	#define MP8859_DEV_ID_REG 0x28
	#define MP8859_IC_REV_REG 0x29

	#define MP8859_MAX_REG 0x29

	#define MP8859_GO_BIT 0x01

	#define MP8859_IOUT_LIM_MASK 0x7f

	#define MP8859_ENABLE_MASK 0x80
	#define MP8859_DISCHG_EN_MASK 0x10
	#define MP8859_MODE_MASK 0x08

	#define MP8859_PG_MASK 0x80
	#define MP8859_OTP_MASK 0x40
	#define MP8859_OTW_MASK 0x20
	#define MP8859_CC_CV_MASK 0x10

	static int mp8859_set_voltage_sel(struct regulator_dev *rdev, unsigned int sel)
	{
	int ret;

	ret = regmap_write(rdev->regmap, MP8859_VOUT_L_REG, sel & 0x7);

	if (ret)
	return ret;
	ret = regmap_write(rdev->regmap, MP8859_VOUT_H_REG, sel >> 3);

	if (ret)
	return ret;
	ret = regmap_update_bits(rdev->regmap, MP8859_VOUT_GO_REG,
	MP8859_GO_BIT, 1);
	return ret;
	}

	static int mp8859_get_voltage_sel(struct regulator_dev *rdev)
	{
	unsigned int val_tmp;
	unsigned int val;
	int ret;

	ret = regmap_read(rdev->regmap, MP8859_VOUT_H_REG, &val_tmp);

	if (ret)
	return ret;
	val = val_tmp << 3;

	ret = regmap_read(rdev->regmap, MP8859_VOUT_L_REG, &val_tmp);

	if (ret)
	return ret;
	val \|= val_tmp & 0x07;
	return val;
	}

	static int mp8859_set_voltage_time_sel(struct regulator_dev *rdev,
	unsigned int from, unsigned int to)
	{
	int change;

	/* The voltage ramps at 1mV/uS, selectors are 10mV */
	if (from > to)
	change = from - to;
	else
	change = to - from;

	return change * 10 * 1000;
	}

	static unsigned int mp8859_get_mode(struct regulator_dev *rdev)
	{
	unsigned int val;
	int ret;

	ret = regmap_read(rdev->regmap, MP8859_CTL1_REG, &val);
	if (ret != 0) {
	dev_err(&rdev->dev, "Failed to read mode: %d\n", ret);
	return 0;
	}

	if (val & MP8859_MODE_MASK)
	return REGULATOR_MODE_FAST;
	else
	return REGULATOR_MODE_NORMAL;
	}

	static int mp8859_set_mode(struct regulator_dev *rdev, unsigned int mode)
	{
	unsigned int val;

	switch (mode) {
	case REGULATOR_MODE_FAST:
	val = MP8859_MODE_MASK;
	break;
	case REGULATOR_MODE_NORMAL:
	val = 0;
	break;
	default:
	return -EINVAL;
	}

	return regmap_update_bits(rdev->regmap, MP8859_CTL1_REG,
	MP8859_MODE_MASK, val);
	}

	static int mp8859_set_current_limit(struct regulator_dev *rdev,
	int min_uA, int max_uA)
	{
	unsigned int cur_val, new_val;
	int ret, i;

	/* Steps of 50mA */
	new_val = max_uA / 50000;
	if (new_val > MP8859_IOUT_LIM_MASK)
	return -EINVAL;
	if (new_val == 0)
	return -EINVAL;

	/*
	* If the regulator is limiting then ramp gradually as per
	* datasheet, otherwise just set the value directly.
	*/
	ret = regmap_read(rdev->regmap, MP8859_STATUS_REG, &cur_val);
	if (ret != 0)
	return ret;
	if (!(cur_val & MP8859_CC_CV_MASK)) {
	return regmap_update_bits(rdev->regmap, MP8859_IOUT_LIM_REG,
	MP8859_IOUT_LIM_MASK, new_val);
	}

	ret = regmap_read(rdev->regmap, MP8859_IOUT_LIM_REG, &cur_val);
	if (ret != 0)
	return ret;

	if (cur_val >= new_val) {
	for (i = cur_val; i >= new_val; i--) {
	ret = regmap_update_bits(rdev->regmap,
	MP8859_IOUT_LIM_REG,
	MP8859_IOUT_LIM_MASK,
	cur_val - i);
	if (ret != 0)
	return ret;
	}
	} else {
	for (i = cur_val; i <= new_val; i++) {
	ret = regmap_update_bits(rdev->regmap,
	MP8859_IOUT_LIM_REG,
	MP8859_IOUT_LIM_MASK,
	cur_val + i);
	if (ret != 0)
	return ret;
	}
	}

	return 0;
	}

	static int mp8859_get_status(struct regulator_dev *rdev)
	{
	unsigned int val;
	int ret;

	/* Output status is only meaingful when enabled */
	ret = regmap_read(rdev->regmap, MP8859_CTL1_REG, &val);
	if (ret != 0)
	return ret;
	if (!(val & MP8859_ENABLE_MASK))
	return REGULATOR_STATUS_UNDEFINED;

	ret = regmap_read(rdev->regmap, MP8859_STATUS_REG, &val);
	if (ret != 0)
	return ret;

	if (val & MP8859_PG_MASK)
	return REGULATOR_STATUS_ON;
	else
	return REGULATOR_STATUS_ERROR;
	}

	static int mp8859_get_error_flags(struct regulator_dev *rdev,
	unsigned int *flags)
	{
	unsigned int status, enabled;
	int ret;

	*flags = 0;

	/* Output status is only meaingful when enabled */
	ret = regmap_read(rdev->regmap, MP8859_CTL1_REG, &enabled);
	if (ret != 0)
	return ret;
	enabled &= MP8859_ENABLE_MASK;

	ret = regmap_read(rdev->regmap, MP8859_STATUS_REG, &status);
	if (ret != 0)
	return ret;

	if (enabled && !(status & MP8859_PG_MASK))
	status \|= REGULATOR_ERROR_FAIL;
	if (status & MP8859_OTP_MASK)
	status \|= REGULATOR_ERROR_OVER_TEMP;
	if (status & MP8859_OTW_MASK)
	status \|= REGULATOR_ERROR_OVER_TEMP_WARN;
	if (status & MP8859_CC_CV_MASK)
	status \|= REGULATOR_ERROR_OVER_CURRENT;

	return 0;
	}

	static const struct linear_range mp8859_dcdc_ranges[] = {
	REGULATOR_LINEAR_RANGE(0, VOL_MIN_IDX, VOL_MAX_IDX, 10000),
	};

	static bool mp8859_readable(struct device *dev, unsigned int reg)
	{
	switch (reg) {
	case MP8859_VOUT_L_REG:
	case MP8859_VOUT_H_REG:
	case MP8859_VOUT_GO_REG:
	case MP8859_IOUT_LIM_REG:
	case MP8859_CTL1_REG:
	case MP8859_CTL2_REG:
	case MP8859_STATUS_REG:
	case MP8859_INTERRUPT_REG:
	case MP8859_MASK_REG:
	case MP8859_ID1_REG:
	case MP8859_MFR_ID_REG:
	case MP8859_DEV_ID_REG:
	case MP8859_IC_REV_REG:
	return true;
	default:
	return false;
	}
	}

	static bool mp8859_volatile(struct device *dev, unsigned int reg)
	{
	switch (reg) {
	case MP8859_VOUT_GO_REG:
	case MP8859_STATUS_REG:
	case MP8859_INTERRUPT_REG:
	return true;
	default:
	return false;
	}
	}

	static const struct regmap_config mp8859_regmap = {
	.reg_bits = 8,
	.val_bits = 8,
	.max_register = MP8859_MAX_REG,
	.cache_type = REGCACHE_MAPLE,
	.readable_reg = mp8859_readable,
	.volatile_reg = mp8859_volatile,
	};

	static const struct regulator_ops mp8859_ops = {
	.set_voltage_sel = mp8859_set_voltage_sel,
	.get_voltage_sel = mp8859_get_voltage_sel,
	.list_voltage = regulator_list_voltage_linear_range,
	.set_voltage_time_sel = mp8859_set_voltage_time_sel,
	.enable = regulator_enable_regmap,
	.disable = regulator_disable_regmap,
	.is_enabled = regulator_is_enabled_regmap,
	.set_mode = mp8859_set_mode,
	.get_mode = mp8859_get_mode,
	.set_active_discharge = regulator_set_active_discharge_regmap,
	.set_current_limit = mp8859_set_current_limit,
	.get_status = mp8859_get_status,
	.get_error_flags = mp8859_get_error_flags,
	};

	static const struct regulator_desc mp8859_regulators[] = {
	{
	.id = 0,
	.type = REGULATOR_VOLTAGE,
	.name = "mp8859_dcdc",
	.supply_name = "vin",
	.of_match = of_match_ptr("mp8859_dcdc"),
	.n_voltages = VOL_MAX_IDX + 1,
	.linear_ranges = mp8859_dcdc_ranges,
	.n_linear_ranges = 1,
	.enable_reg = MP8859_CTL1_REG,
	.enable_mask = MP8859_ENABLE_MASK,
	.enable_val = MP8859_ENABLE_MASK,
	.active_discharge_reg = MP8859_CTL1_REG,
	.active_discharge_on = MP8859_DISCHG_EN_MASK,
	.active_discharge_mask = MP8859_DISCHG_EN_MASK,
	.ops = &mp8859_ops,
	.owner = THIS_MODULE,
	},
	};

	static int mp8859_i2c_probe(struct i2c_client *i2c)
	{
	int ret;
	struct regulator_config config = {.dev = &i2c->dev};
	struct regmap *regmap = devm_regmap_init_i2c(i2c, &mp8859_regmap);
	struct regulator_dev *rdev;
	unsigned int val, rev;

	if (IS_ERR(regmap)) {
	ret = PTR_ERR(regmap);
	dev_err(&i2c->dev, "regmap init failed: %d\n", ret);
	return ret;
	}

	ret = regmap_read(regmap, MP8859_MFR_ID_REG, &val);
	if (ret != 0) {
	dev_err(&i2c->dev, "Failed to read manufacturer ID: %d\n", ret);
	return ret;
	}
	if (val != 0x9) {
	dev_err(&i2c->dev, "Manufacturer ID %x != 9\n", val);
	return -EINVAL;
	}

	ret = regmap_read(regmap, MP8859_DEV_ID_REG, &val);
	if (ret != 0) {
	dev_err(&i2c->dev, "Failed to read device ID: %d\n", ret);
	return ret;
	}
	if (val != 0x58) {
	dev_err(&i2c->dev, "Manufacturer ID %x != 0x58\n", val);
	return -EINVAL;
	}

	ret = regmap_read(regmap, MP8859_IC_REV_REG, &rev);
	if (ret != 0) {
	dev_err(&i2c->dev, "Failed to read device revision: %d\n", ret);
	return ret;
	}
	ret = regmap_read(regmap, MP8859_ID1_REG, &val);
	if (ret != 0) {
	dev_err(&i2c->dev, "Failed to read device ID1: %d\n", ret);
	return ret;
	}
	dev_info(&i2c->dev, "MP8859-%04d revision %d\n", val, rev);

	rdev = devm_regulator_register(&i2c->dev, &mp8859_regulators[0],
	&config);

	if (IS_ERR(rdev)) {
	ret = PTR_ERR(rdev);
	dev_err(&i2c->dev, "failed to register %s: %d\n",
	mp8859_regulators[0].name, ret);
	return ret;
	}
	return 0;
	}

	static const struct of_device_id mp8859_dt_id[] __maybe_unused = {
	{.compatible = "mps,mp8859"},
	{},
	};
	MODULE_DEVICE_TABLE(of, mp8859_dt_id);

	static const struct i2c_device_id mp8859_i2c_id[] = {
	{ "mp8859", },
	{ },
	};
	MODULE_DEVICE_TABLE(i2c, mp8859_i2c_id);

	static struct i2c_driver mp8859_regulator_driver = {
	.driver = {
	.name = "mp8859",
	.probe_type = PROBE_PREFER_ASYNCHRONOUS,
	.of_match_table = of_match_ptr(mp8859_dt_id),
	},
	.probe = mp8859_i2c_probe,
	.id_table = mp8859_i2c_id,
	};

	module_i2c_driver(mp8859_regulator_driver);

	MODULE_DESCRIPTION("Monolithic Power Systems MP8859 voltage regulator driver");
	MODULE_AUTHOR("Markus Reichl <m.reichl@fivetechno.de>");
	MODULE_LICENSE("GPL v2");