regulator: mp8859: add driver

The MP8859 from Monolithic Power Systems is a single output DC/DC
converter. The voltage can be controlled via I2C.
Signed-off-by: Markus Reichl <m.reichl@fivetechno.de>
Link: https://lore.kernel.org/r/20200106211633.2882-2-m.reichl@fivetechno.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/mp8859.c

+// 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
+
+
+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 const struct regulator_linear_range mp8859_dcdc_ranges[] = {
+	REGULATOR_LINEAR_RANGE(0, VOL_MIN_IDX, VOL_MAX_IDX, 10000),
+};
+
+static const struct regmap_config mp8859_regmap = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = MP8859_MAX_REG,
+	.cache_type = REGCACHE_RBTREE,
+};
+
+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,
+};
+
+static const struct regulator_desc mp8859_regulators[] = {
+	{
+		.id = 0,
+		.type = REGULATOR_VOLTAGE,
+		.name = "mp8859_dcdc",
+		.of_match = of_match_ptr("mp8859_dcdc"),
+		.n_voltages = VOL_MAX_IDX + 1,
+		.linear_ranges = mp8859_dcdc_ranges,
+		.n_linear_ranges = 1,
+		.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;
+
+	if (IS_ERR(regmap)) {
+		ret = PTR_ERR(regmap);
+		dev_err(&i2c->dev, "regmap init failed: %d\n", ret);
+		return ret;
+	}
+	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[] = {
+	{.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",
+		.of_match_table = of_match_ptr(mp8859_dt_id),
+	},
+	.probe_new = 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");