regulator: mp886x: add MP8867 support

MP8867 is an I2C-controlled adjustable voltage regulator made by
Monolithic Power Systems. The difference between MP8867 and MP8869
are:
1.If V_BOOT, the vref of MP8869 is fixed at 600mv while vref of
MP8867 is determined by the I2C control.
2.For MP8867, when setting voltage, if the step is within 5, we
need to manually set the GO BIT to 0.
Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Link: https://lore.kernel.org/r/20200316223127.4b1ecc92@xhackerSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/mp886x.c

 // SPDX-License-Identifier: GPL-2.0
 //
-// MP8869 regulator driver
+// MP8867/MP8869 regulator driver
 //
 // Copyright (C) 2020 Synaptics Incorporated
 //
@@ -119,6 +119,62 @@ static const struct regulator_ops mp8869_regulator_ops = {
 	.get_mode = mp886x_get_mode,
 };
 
+static int mp8867_set_voltage_sel(struct regulator_dev *rdev, unsigned int sel)
+{
+	struct mp886x_device_info *di = rdev_get_drvdata(rdev);
+	int ret, delta;
+
+	ret = mp8869_set_voltage_sel(rdev, sel);
+	if (ret < 0)
+		return ret;
+
+	delta = di->sel - sel;
+	if (abs(delta) <= 5)
+		ret = regmap_update_bits(rdev->regmap, MP886X_SYSCNTLREG1,
+					 MP886X_GO, 0);
+	di->sel = sel;
+
+	return ret;
+}
+
+static int mp8867_get_voltage_sel(struct regulator_dev *rdev)
+{
+	struct mp886x_device_info *di = rdev_get_drvdata(rdev);
+	int ret, uv;
+	unsigned int val;
+	bool fbloop;
+
+	ret = regmap_read(rdev->regmap, rdev->desc->vsel_reg, &val);
+	if (ret)
+		return ret;
+
+	fbloop = val & MP886X_V_BOOT;
+
+	val &= rdev->desc->vsel_mask;
+	val >>= ffs(rdev->desc->vsel_mask) - 1;
+
+	if (fbloop) {
+		uv = regulator_list_voltage_linear(rdev, val);
+		uv = mp8869_scale(uv, di->r[0], di->r[1]);
+		return regulator_map_voltage_linear(rdev, uv, uv);
+	}
+
+	return val;
+}
+
+static const struct regulator_ops mp8867_regulator_ops = {
+	.set_voltage_sel = mp8867_set_voltage_sel,
+	.get_voltage_sel = mp8867_get_voltage_sel,
+	.set_voltage_time_sel = regulator_set_voltage_time_sel,
+	.map_voltage = regulator_map_voltage_linear,
+	.list_voltage = regulator_list_voltage_linear,
+	.enable = regulator_enable_regmap,
+	.disable = regulator_disable_regmap,
+	.is_enabled = regulator_is_enabled_regmap,
+	.set_mode = mp886x_set_mode,
+	.get_mode = mp886x_get_mode,
+};
+
 static int mp886x_regulator_register(struct mp886x_device_info *di,
 				     struct regulator_config *config)
 {
@@ -201,6 +257,10 @@ static int mp886x_i2c_probe(struct i2c_client *client,
 }
 
 static const struct of_device_id mp886x_dt_ids[] = {
+	{
+		.compatible = "mps,mp8867",
+		.data = &mp8867_regulator_ops
+	},
 	{
 		.compatible = "mps,mp8869",
 		.data = &mp8869_regulator_ops