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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Monolithic Power Systems MPQ4210 buck-boost regulator
*
* Copyright (c) 2026 Vaisala Oyj
*/
#include <linux/bitfield.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/math.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/of_regulator.h>
#define MPQ4210_REF_LSB 0x00
#define MPQ4210_REF_LSB_MASK GENMASK(2, 0)
#define MPQ4210_REF_LSB_BITS 3
#define MPQ4210_REF_MSB 0x01
#define MPQ4210_CONTROL1 0x02
#define MPQ4210_CONTROL1_SR GENMASK(7, 6)
#define MPQ4210_CONTROL1_RESERVED BIT(2)
#define MPQ4210_CONTROL1_GO BIT(1)
#define MPQ4210_CONTROL1_ENPWR BIT(0)
#define MPQ4210_INT_MASK 0x06
/*
* The feedback reference is an 11 bit value with a 1mV step. The datasheet
* specifies no reference below 0.3V, so those selectors are not offered.
*/
#define MPQ4210_REF_MIN 0x12c
#define MPQ4210_REF_MAX 0x7ff
#define MPQ4210_REF_STEP_UV 1000
#define MPQ4210_ENPWR_DELAY_MS 200
/* Feedback reference slew rate per MPQ4210_CONTROL1_SR value, in uV/us. */
static const unsigned int mpq4210_ref_slew_rate[] = { 38, 50, 75, 150 };
static const struct regmap_config mpq4210_regmap_config = {
.reg_bits = 8,
.val_bits = 8,
.max_register = MPQ4210_INT_MASK,
};
/* Scale a feedback reference value by the output voltage divider ratio. */
static unsigned int mpq4210_scale(unsigned int val, u32 r1, u32 r2)
{
u64 tmp = (u64)val * (r1 + r2);
do_div(tmp, r2);
return tmp;
}
static int mpq4210_set_voltage_sel(struct regulator_dev *rdev, unsigned int sel)
{
int ret;
ret = regmap_write(rdev->regmap, MPQ4210_REF_LSB,
sel & MPQ4210_REF_LSB_MASK);
if (ret)
return ret;
ret = regmap_write(rdev->regmap, MPQ4210_REF_MSB,
sel >> MPQ4210_REF_LSB_BITS);
if (ret)
return ret;
return regmap_set_bits(rdev->regmap, MPQ4210_CONTROL1,
MPQ4210_CONTROL1_GO);
}
static int mpq4210_get_voltage_sel(struct regulator_dev *rdev)
{
unsigned int lsb, msb;
int ret;
ret = regmap_read(rdev->regmap, MPQ4210_REF_MSB, &msb);
if (ret)
return ret;
ret = regmap_read(rdev->regmap, MPQ4210_REF_LSB, &lsb);
if (ret)
return ret;
return (msb << MPQ4210_REF_LSB_BITS) | (lsb & MPQ4210_REF_LSB_MASK);
}
static int mpq4210_enable(struct regulator_dev *rdev)
{
int ret;
ret = regmap_set_bits(rdev->regmap, MPQ4210_CONTROL1,
MPQ4210_CONTROL1_GO);
if (ret)
return ret;
/* The reference has to settle before power switching may start. */
msleep(MPQ4210_ENPWR_DELAY_MS);
return regmap_set_bits(rdev->regmap, MPQ4210_CONTROL1,
MPQ4210_CONTROL1_ENPWR);
}
static const struct regulator_ops mpq4210_regulator_ops = {
.set_voltage_sel = mpq4210_set_voltage_sel,
.get_voltage_sel = mpq4210_get_voltage_sel,
.list_voltage = regulator_list_voltage_linear,
.set_ramp_delay = regulator_set_ramp_delay_regmap,
.enable = mpq4210_enable,
.disable = regulator_disable_regmap,
.is_enabled = regulator_is_enabled_regmap,
};
static const struct regulator_desc mpq4210_regulator = {
.name = "mpq4210",
.type = REGULATOR_VOLTAGE,
.owner = THIS_MODULE,
.ops = &mpq4210_regulator_ops,
.n_voltages = MPQ4210_REF_MAX + 1,
.linear_min_sel = MPQ4210_REF_MIN,
.enable_reg = MPQ4210_CONTROL1,
.enable_mask = MPQ4210_CONTROL1_ENPWR,
.ramp_reg = MPQ4210_CONTROL1,
.ramp_mask = MPQ4210_CONTROL1_SR,
.n_ramp_values = ARRAY_SIZE(mpq4210_ref_slew_rate),
};
static int mpq4210_i2c_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
struct regulator_config config = { };
struct regulator_desc *desc;
struct regulator_dev *rdev;
struct gpio_desc *enable;
struct regmap *regmap;
unsigned int *slew;
unsigned int i, val;
u32 r[2];
int ret;
ret = of_property_read_u32_array(dev->of_node,
"mps,fb-voltage-divider-ohms",
r, ARRAY_SIZE(r));
if (ret)
return dev_err_probe(dev, ret,
"failed to read mps,fb-voltage-divider-ohms\n");
if (!r[1])
return dev_err_probe(dev, -EINVAL,
"feedback divider R2 must not be zero\n");
/* The controller does not answer on the bus while EN is deasserted. */
enable = devm_gpiod_get_optional(dev, "enable", GPIOD_OUT_HIGH);
if (IS_ERR(enable))
return dev_err_probe(dev, PTR_ERR(enable),
"failed to get enable GPIO\n");
regmap = devm_regmap_init_i2c(client, &mpq4210_regmap_config);
if (IS_ERR(regmap))
return dev_err_probe(dev, PTR_ERR(regmap),
"failed to init regmap\n");
desc = devm_kmemdup(dev, &mpq4210_regulator, sizeof(*desc), GFP_KERNEL);
if (!desc)
return -ENOMEM;
desc->min_uV = mpq4210_scale(MPQ4210_REF_MIN * MPQ4210_REF_STEP_UV,
r[0], r[1]);
desc->uV_step = mpq4210_scale(MPQ4210_REF_STEP_UV, r[0], r[1]);
slew = devm_kcalloc(dev, ARRAY_SIZE(mpq4210_ref_slew_rate),
sizeof(*slew), GFP_KERNEL);
if (!slew)
return -ENOMEM;
for (i = 0; i < ARRAY_SIZE(mpq4210_ref_slew_rate); i++)
slew[i] = mpq4210_scale(mpq4210_ref_slew_rate[i], r[0], r[1]);
desc->ramp_delay_table = slew;
ret = regmap_read(regmap, MPQ4210_CONTROL1, &val);
if (ret)
return dev_err_probe(dev, ret, "failed to read control 1\n");
/* The core overrides this if the board sets regulator-ramp-delay. */
desc->ramp_delay = slew[FIELD_GET(MPQ4210_CONTROL1_SR, val)];
/*
* Documented as reserved, but the datasheet requires it to be set
* before the controller starts up.
*/
ret = regmap_set_bits(regmap, MPQ4210_CONTROL1,
MPQ4210_CONTROL1_RESERVED);
if (ret)
return dev_err_probe(dev, ret, "failed to write control 1\n");
config.dev = dev;
config.regmap = regmap;
config.of_node = dev->of_node;
config.init_data = of_get_regulator_init_data(dev, dev->of_node, desc);
if (!config.init_data)
return -ENOMEM;
rdev = devm_regulator_register(dev, desc, &config);
if (IS_ERR(rdev))
return dev_err_probe(dev, PTR_ERR(rdev),
"failed to register regulator\n");
return 0;
}
static const struct of_device_id mpq4210_of_match[] = {
{ .compatible = "mps,mpq4210" },
{ }
};
MODULE_DEVICE_TABLE(of, mpq4210_of_match);
static const struct i2c_device_id mpq4210_i2c_id[] = {
{ .name = "mpq4210" },
{ }
};
MODULE_DEVICE_TABLE(i2c, mpq4210_i2c_id);
static struct i2c_driver mpq4210_regulator_driver = {
.driver = {
.name = "mpq4210",
.probe_type = PROBE_PREFER_ASYNCHRONOUS,
.of_match_table = mpq4210_of_match,
},
.probe = mpq4210_i2c_probe,
.id_table = mpq4210_i2c_id,
};
module_i2c_driver(mpq4210_regulator_driver);
MODULE_DESCRIPTION("Monolithic Power Systems MPQ4210 voltage regulator driver");
MODULE_AUTHOR("Tapio Reijonen <tapio.reijonen@vaisala.com>");
MODULE_LICENSE("GPL");
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