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Message-Id: <DCSMM4ZWOFI3.1O1X64E61A7DA@mentallysanemainliners.org>
Date: Sun, 14 Sep 2025 17:25:29 +0200
From: "Igor Belwon" <igor.belwon@...tallysanemainliners.org>
To: "Ivaylo Ivanov" <ivo.ivanov.ivanov1@...il.com>, "Krzysztof Kozlowski"
<krzk@...nel.org>, "Rob Herring" <robh@...nel.org>, "Liam Girdwood"
<lgirdwood@...il.com>, "Mark Brown" <broonie@...nel.org>
Cc: <linux-samsung-soc@...r.kernel.org>, <devicetree@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 2/2] regulator: max77838: add max77838 regulator
driver
Hi Ivaylo,
On Sun Sep 14, 2025 at 3:02 PM CEST, Ivaylo Ivanov wrote:
> The max77838 PMIC contains a BUCK regulator and 4 LDOs. It's primarily
> used in the Samsung Galaxy S7 lineup and is accessed over I2C.
>
> Signed-off-by: Ivaylo Ivanov <ivo.ivanov.ivanov1@...il.com>
> ---
> MAINTAINERS | 1 +
> drivers/regulator/Kconfig | 8 +
> drivers/regulator/Makefile | 1 +
> drivers/regulator/max77838-regulator.c | 221 +++++++++++++++++++++++++
> 4 files changed, 231 insertions(+)
> create mode 100644 drivers/regulator/max77838-regulator.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index a4916a178..276374ba7 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15066,6 +15066,7 @@ M: Ivaylo Ivanov <ivo.ivanov.ivanov1@...il.com>
> L: linux-kernel@...r.kernel.org
> S: Maintained
> F: Documentation/devicetree/bindings/regulator/maxim,max77838.yaml
> +F: drivers/regulator/max77838-regulator.c
>
> MAXIM MAX77976 BATTERY CHARGER
> M: Luca Ceresoli <luca@...aceresoli.net>
> diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
> index 41b56b647..18601bdc0 100644
> --- a/drivers/regulator/Kconfig
> +++ b/drivers/regulator/Kconfig
> @@ -777,6 +777,14 @@ config REGULATOR_MAX77826
> It includes support for control of output voltage. This
> regulator is found on the Samsung Galaxy S5 (klte) smartphone.
>
> +config REGULATOR_MAX77838
> + tristate "Maxim 77838 regulator"
> + depends on REGMAP_I2C
REGMAP_I2C should be selected by the driver.
The driver should depend on I2C.
> + help
> + This driver controls a Maxim 77838 regulator via I2C bus.
> + The regulator include 4 LDOs and a BUCK regulator. It's
> + present on the Samsung Galaxy S7 lineup of smartphones.
> +
> config REGULATOR_MC13XXX_CORE
> tristate
>
> diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
> index be98b29d6..0622e9de6 100644
> --- a/drivers/regulator/Makefile
> +++ b/drivers/regulator/Makefile
> @@ -92,6 +92,7 @@ obj-$(CONFIG_REGULATOR_MAX77686) += max77686-regulator.o
> obj-$(CONFIG_REGULATOR_MAX77693) += max77693-regulator.o
> obj-$(CONFIG_REGULATOR_MAX77802) += max77802-regulator.o
> obj-$(CONFIG_REGULATOR_MAX77826) += max77826-regulator.o
> +obj-$(CONFIG_REGULATOR_MAX77838) += max77838-regulator.o
> obj-$(CONFIG_REGULATOR_MAX77857) += max77857-regulator.o
> obj-$(CONFIG_REGULATOR_MC13783) += mc13783-regulator.o
> obj-$(CONFIG_REGULATOR_MC13892) += mc13892-regulator.o
> diff --git a/drivers/regulator/max77838-regulator.c b/drivers/regulator/max77838-regulator.c
> new file mode 100644
> index 000000000..9faddbfd2
> --- /dev/null
> +++ b/drivers/regulator/max77838-regulator.c
> @@ -0,0 +1,221 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +//
> +// regulator driver for Maxim MAX77838
> +//
> +// based on max77826-regulator.c
> +//
> +// Copyright (c) 2025, Ivaylo Ivanov <ivo.ivanov.ivanov1@...il.com>
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/err.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/driver.h>
> +#include <linux/regulator/of_regulator.h>
> +#include <linux/i2c.h>
> +#include <linux/regmap.h>
> +
> +enum max77838_registers {
> + MAX77838_REG_DEVICE_ID = 0x00,
> + MAX77838_REG_TOPSYS_STAT,
> + MAX77838_REG_STAT,
> + MAX77838_REG_EN,
> + MAX77838_REG_GPIO_PD_CTRL,
> + MAX77838_REG_UVLO_CFG1,
> + /* 0x06 - 0x0B: reserved */
> + MAX77838_REG_I2C_CFG = 0x0C,
> + /* 0x0D - 0x0F: reserved */
> + MAX77838_REG_LDO1_CFG = 0x10,
> + MAX77838_REG_LDO2_CFG,
> + MAX77838_REG_LDO3_CFG,
> + MAX77838_REG_LDO4_CFG,
> + /* 0x14 - 0x1F: reserved */
> + MAX77838_REG_BUCK_CFG1 = 0x20,
> + MAX77838_REG_BUCK_VOUT,
> +};
> +
> +enum max77838_regulators {
> + MAX77838_LDO1 = 0,
> + MAX77838_LDO2,
> + MAX77838_LDO3,
> + MAX77838_LDO4,
> + MAX77838_BUCK,
> + MAX77838_MAX_REGULATORS,
> +};
> +
> +#define MAX77838_MASK_LDO 0x7f
> +#define MAX77838_MASK_BUCK 0xff
> +
> +#define MAX77838_LDO1_EN BIT(0)
> +#define MAX77838_LDO2_EN BIT(1)
> +#define MAX77838_LDO3_EN BIT(2)
> +#define MAX77838_LDO4_EN BIT(3)
> +#define MAX77838_BUCK_EN BIT(4)
> +
> +#define MAX77838_BUCK_AD BIT(3)
> +#define MAX77838_LDO_AD BIT(7)
> +
> +#define MAX77838_LDO_VOLT_MIN 600000
> +#define MAX77838_LDO_VOLT_MAX 3775000
> +#define MAX77838_LDO_VOLT_STEP 25000
> +
> +#define MAX77838_BUCK_VOLT_MIN 500000
> +#define MAX77838_BUCK_VOLT_MAX 2093750
> +#define MAX77838_BUCK_VOLT_STEP 6250
> +
> +#define MAX77838_VOLT_RANGE(_type) \
> + ((MAX77838_ ## _type ## _VOLT_MAX - \
> + MAX77838_ ## _type ## _VOLT_MIN) / \
> + MAX77838_ ## _type ## _VOLT_STEP + 1)
> +
> +#define MAX77838_LDO(_id) \
> + [MAX77838_LDO ## _id] = { \
> + .id = MAX77838_LDO ## _id, \
> + .name = "ldo"#_id, \
> + .of_match = of_match_ptr("ldo"#_id), \
> + .regulators_node = "regulators", \
> + .ops = &max77838_regulator_ops, \
> + .min_uV = MAX77838_LDO_VOLT_MIN, \
> + .uV_step = MAX77838_LDO_VOLT_STEP, \
> + .n_voltages = MAX77838_VOLT_RANGE(LDO), \
> + .enable_reg = MAX77838_REG_EN, \
> + .enable_mask = MAX77838_LDO ## _id ## _EN, \
> + .vsel_reg = MAX77838_REG_LDO ## _id ## _CFG, \
> + .vsel_mask = MAX77838_MASK_LDO, \
> + .active_discharge_off = 0, \
> + .active_discharge_on = MAX77838_LDO_AD, \
> + .active_discharge_mask = MAX77838_LDO_AD, \
> + .active_discharge_reg = MAX77838_REG_LDO ## _id ## _CFG, \
> + .owner = THIS_MODULE, \
> + }
> +
> +#define MAX77838_BUCK_DESC \
> + [MAX77838_BUCK] = { \
> + .id = MAX77838_BUCK, \
> + .name = "buck", \
> + .of_match = of_match_ptr("buck"), \
> + .regulators_node = "regulators", \
> + .ops = &max77838_regulator_ops, \
> + .min_uV = MAX77838_BUCK_VOLT_MIN, \
> + .uV_step = MAX77838_BUCK_VOLT_STEP, \
> + .n_voltages = MAX77838_VOLT_RANGE(BUCK), \
> + .enable_reg = MAX77838_REG_EN, \
> + .enable_mask = MAX77838_BUCK_EN, \
> + .vsel_reg = MAX77838_REG_BUCK_VOUT, \
> + .vsel_mask = MAX77838_MASK_BUCK, \
> + .active_discharge_off = 0, \
> + .active_discharge_on = MAX77838_BUCK_AD, \
> + .active_discharge_mask = MAX77838_BUCK_AD, \
> + .active_discharge_reg = MAX77838_REG_BUCK_CFG1, \
> + .owner = THIS_MODULE, \
> + }
> +
nit: Could you make the indentation between VOLT_RANGE, LDO and
BUCK_DESC consistent?
> +struct max77838_regulator_info {
> + struct regmap *regmap;
> +};
> +
> +static const struct regmap_config max77838_regmap_config = {
> + .reg_bits = 8,
> + .val_bits = 8,
> + .max_register = MAX77838_REG_BUCK_VOUT,
> +};
> +
> +static const struct regulator_ops max77838_regulator_ops = {
> + .enable = regulator_enable_regmap,
> + .disable = regulator_disable_regmap,
> + .is_enabled = regulator_is_enabled_regmap,
> + .list_voltage = regulator_list_voltage_linear,
> + .map_voltage = regulator_map_voltage_linear,
> + .get_voltage_sel = regulator_get_voltage_sel_regmap,
> + .set_voltage_sel = regulator_set_voltage_sel_regmap,
> + .set_active_discharge = regulator_set_active_discharge_regmap,
> +};
> +
> +static const struct regulator_desc max77838_regulators_desc[] = {
> + MAX77838_LDO(1),
> + MAX77838_LDO(2),
> + MAX77838_LDO(3),
> + MAX77838_LDO(4),
> + MAX77838_BUCK_DESC,
> +};
> +
> +static int max77838_read_device_id(struct regmap *regmap, struct device *dev)
> +{
> + unsigned int device_id;
> + int ret;
> +
> + ret = regmap_read(regmap, MAX77838_REG_DEVICE_ID, &device_id);
> + if (!ret)
> + dev_dbg(dev, "DEVICE_ID: 0x%x\n", device_id);
> +
> + return ret;
> +}
> +
> +static int max77838_i2c_probe(struct i2c_client *client)
> +{
> + struct device *dev = &client->dev;
> + struct max77838_regulator_info *info;
> + struct regulator_config config = {};
> + struct regulator_dev *rdev;
> + struct regmap *regmap;
> + int i;
> +
> + info = devm_kzalloc(dev, sizeof(struct max77838_regulator_info),
> + GFP_KERNEL);
> + if (!info)
> + return -ENOMEM;
> +
> + regmap = devm_regmap_init_i2c(client, &max77838_regmap_config);
> + if (IS_ERR(regmap)) {
> + dev_err(dev, "Failed to allocate regmap!\n");
> + return PTR_ERR(regmap);
> + }
> +
> + info->regmap = regmap;
> + i2c_set_clientdata(client, info);
> +
> + config.dev = dev;
> + config.regmap = regmap;
> + config.driver_data = info;
> +
> + for (i = 0; i < MAX77838_MAX_REGULATORS; i++) {
> + rdev = devm_regulator_register(dev,
> + &max77838_regulators_desc[i],
> + &config);
> + if (IS_ERR(rdev)) {
> + dev_err(dev, "Failed to register regulator!\n");
> + return PTR_ERR(rdev);
> + }
> + }
> +
> + return max77838_read_device_id(regmap, dev);
> +}
> +
> +static const struct of_device_id __maybe_unused max77838_of_match[] = {
> + { .compatible = "maxim,max77838" },
> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, max77838_of_match);
> +
> +static const struct i2c_device_id max77838_id[] = {
> + { "max77838-regulator" },
> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(i2c, max77838_id);
> +
> +static struct i2c_driver max77838_regulator_driver = {
> + .driver = {
> + .name = "max77838",
> + .probe_type = PROBE_PREFER_ASYNCHRONOUS,
> + .of_match_table = of_match_ptr(max77838_of_match),
> + },
> + .probe = max77838_i2c_probe,
> + .id_table = max77838_id,
> +};
> +module_i2c_driver(max77838_regulator_driver);
> +
> +MODULE_AUTHOR("Ivaylo Ivanov <ivo.ivanov.ivanov1@...il.com>");
> +MODULE_DESCRIPTION("MAX77838 PMIC regulator driver");
> +MODULE_LICENSE("GPL");
Kind regards,
Igor
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