regulator: Introduce Maxim MAX20411 Step-Down converter

Introduce a driver to control the Maxim MAX20411 family of
high-efficiency, syncrhonous step-down converters.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Link: https://lore.kernel.org/r/20230124184440.1421074-3-quic_bjorande@quicinc.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/Kconfig

@@ -655,6 +655,14 @@ config REGULATOR_MAX20086
 	  protectorvia I2C bus. The regulator has 2 or 4 outputs depending on
 	  the device model. This driver is only capable to turn on/off them.
 
+config REGULATOR_MAX20411
+	tristate "Maxim MAX20411 High-Efficiency Single Step-Down Converter"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  This driver controls the Maxim MAX20411 family of high-efficiency,
+	  syncrhonous step-down converters.
+
 config REGULATOR_MAX77686
 	tristate "Maxim 77686 regulator"
 	depends on MFD_MAX77686 || COMPILE_TEST

drivers/regulator/Makefile

@@ -80,6 +80,7 @@ obj-$(CONFIG_REGULATOR_MAX8973) += max8973-regulator.o
 obj-$(CONFIG_REGULATOR_MAX8997) += max8997-regulator.o
 obj-$(CONFIG_REGULATOR_MAX8998) += max8998.o
 obj-$(CONFIG_REGULATOR_MAX20086) += max20086-regulator.o
+obj-$(CONFIG_REGULATOR_MAX20411) += max20411-regulator.o
 obj-$(CONFIG_REGULATOR_MAX77686) += max77686-regulator.o
 obj-$(CONFIG_REGULATOR_MAX77693) += max77693-regulator.o
 obj-$(CONFIG_REGULATOR_MAX77802) += max77802-regulator.o

drivers/regulator/max20411-regulator.c

@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2021, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2022, Linaro Ltd.
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/regmap.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regulator/of_regulator.h>
+
+#define MAX20411_UV_STEP		6250
+#define MAX20411_BASE_UV		243750
+#define MAX20411_MIN_SEL		41 /* 0.5V */
+#define MAX20411_MAX_SEL		165 /* 1.275V */
+#define MAX20411_VID_OFFSET		0x7
+#define MAX20411_VID_MASK		0xff
+#define MAX20411_SLEW_OFFSET		0x6
+#define MAX20411_SLEW_DVS_MASK		0xc
+#define MAX20411_SLEW_SR_MASK		0x3
+
+struct max20411 {
+	struct device *dev;
+	struct device_node *of_node;
+	struct regulator_desc desc;
+	struct regulator_dev *rdev;
+	struct regmap *regmap;
+};
+
+static const unsigned int max20411_slew_rates[] = { 13100, 6600, 3300, 1600 };
+
+static int max20411_enable_time(struct regulator_dev *rdev)
+{
+	int voltage, rate, ret;
+	unsigned int val;
+
+	/* get voltage */
+	ret = regmap_read(rdev->regmap, rdev->desc->vsel_reg, &val);
+	if (ret)
+		return ret;
+
+	val &= rdev->desc->vsel_mask;
+	voltage = regulator_list_voltage_linear(rdev, val);
+
+	/* get rate */
+	ret = regmap_read(rdev->regmap, MAX20411_SLEW_OFFSET, &val);
+	if (ret)
+		return ret;
+
+	val = FIELD_GET(MAX20411_SLEW_SR_MASK, val);
+	rate = max20411_slew_rates[val];
+
+	return DIV_ROUND_UP(voltage, rate);
+}
+
+static const struct regmap_config max20411_regmap_config = {
+	.reg_bits		= 8,
+	.val_bits		= 8,
+	.max_register		= 0xe,
+};
+
+static const struct regulator_ops max20411_ops = {
+	.get_voltage_sel	= regulator_get_voltage_sel_regmap,
+	.set_voltage_sel	= regulator_set_voltage_sel_regmap,
+	.list_voltage		= regulator_list_voltage_linear,
+	.enable_time		= max20411_enable_time,
+};
+
+static const struct regulator_desc max20411_desc = {
+	.ops = &max20411_ops,
+	.owner = THIS_MODULE,
+	.type = REGULATOR_VOLTAGE,
+	.supply_name = "vin",
+	.name = "max20411",
+
+	/*
+	 * voltage = 0.24375V + selector * 6.25mV
+	 * with valid selector between 41 to 165 (0.5V to 1.275V)
+	 */
+	.min_uV = MAX20411_BASE_UV,
+	.uV_step = MAX20411_UV_STEP,
+	.linear_min_sel = MAX20411_MIN_SEL,
+	.n_voltages = MAX20411_MAX_SEL,
+
+	.vsel_reg = MAX20411_VID_OFFSET,
+	.vsel_mask = MAX20411_VID_MASK,
+
+	.ramp_reg = MAX20411_SLEW_OFFSET,
+	.ramp_mask = MAX20411_SLEW_DVS_MASK,
+	.ramp_delay_table = max20411_slew_rates,
+	.n_ramp_values = ARRAY_SIZE(max20411_slew_rates),
+};
+
+static int max20411_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct regulator_init_data *init_data;
+	struct device *dev = &client->dev;
+	struct regulator_config cfg = {};
+	struct max20411 *max20411;
+
+	max20411 = devm_kzalloc(dev, sizeof(*max20411), GFP_KERNEL);
+	if (!max20411)
+		return -ENOMEM;
+
+	max20411->regmap = devm_regmap_init_i2c(client, &max20411_regmap_config);
+	if (IS_ERR(max20411->regmap)) {
+		dev_err(dev, "Failed to allocate regmap!\n");
+		return PTR_ERR(max20411->regmap);
+	}
+
+	max20411->dev = dev;
+	max20411->of_node = dev->of_node;
+
+	max20411->desc = max20411_desc;
+	init_data = of_get_regulator_init_data(max20411->dev, max20411->of_node, &max20411->desc);
+	if (!init_data)
+		return -ENODATA;
+
+	cfg.dev = max20411->dev;
+	cfg.init_data = init_data;
+	cfg.of_node = max20411->of_node;
+	cfg.driver_data = max20411;
+
+	cfg.ena_gpiod = gpiod_get(max20411->dev, "enable", GPIOD_ASIS);
+	if (IS_ERR(cfg.ena_gpiod))
+		return dev_err_probe(dev, PTR_ERR(cfg.ena_gpiod),
+				     "unable to acquire enable gpio\n");
+
+	max20411->rdev = devm_regulator_register(max20411->dev, &max20411->desc, &cfg);
+	if (IS_ERR(max20411->rdev))
+		dev_err(max20411->dev, "Failed to register regulator\n");
+
+	return PTR_ERR_OR_ZERO(max20411->rdev);
+}
+
+static const struct of_device_id of_max20411_match_tbl[] = {
+	{ .compatible = "maxim,max20411", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, of_max20411_match_tbl);
+
+static const struct i2c_device_id max20411_id[] = {
+	{ "max20411", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, max20411_id);
+
+static struct i2c_driver max20411_i2c_driver = {
+	.driver	= {
+		.name = "max20411",
+		.of_match_table	= of_max20411_match_tbl,
+	},
+	.probe = max20411_probe,
+	.id_table = max20411_id,
+};
+module_i2c_driver(max20411_i2c_driver);
+
+MODULE_LICENSE("GPL");