new file mode 100644
@@ -0,0 +1,156 @@
+// 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");
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> --- drivers/regulator/mp8859.c | 156 +++++++++++++++++++++++++++++++++++++ 1 file changed, 156 insertions(+) create mode 100644 drivers/regulator/mp8859.c