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Changing voltage might ignore slew rate and cause a current surge. With current implementation the driver will get the regulator to change the voltage range used during run time. According to communication I have had with Texas Instruments, this is not intended, since the Dynamic Voltage Scaling in the hardware is only designed to work within a voltage range. The current implementation will therefore ignore the slew rate that is defined in devicetree when the voltage range is changed during use. The current implementation will always select a voltage in the most accurate range that can reach that voltage even though multiple ranges are able to reach that voltage. There are 4 Voltage ranges with the following reach: 0b00: 0.4-0.71875V (1.25mV step size) 0b01: 0.4-1.0375V (2.5mV) 0b10: 0.4-1.675V (5mV) 0b11: 0.8-3.3V (10mV) This in practice means that a change from below to above 0.71875V will use the smallest range(0b00) for the values below and the second smallest range(0b01) for the voltages above (Up to 1.675V). I have timed how long it takes to go from below 0.71875V to above. The increase was 100mV which, with the slew rate set to 1250µV/µs. This in theory should take 80µs to do. With the current implementation, it takes 10µs on my hardware. Doing the same test with the slew rate set to 5000µV/µs, which should take 20µs, also only takes 10µs to do on my hardware. Not only is this not in line with the technical specification for the regulator. It also causes a current surge. Which when calculating the output current, as described in the technical specification, compared to what I could observe on my hardware the real output is ~1A higher (~1.2A) than what I calculated it to be(~0.2A). I tested also transitioning from a bigger to a smaller range, and the results were the same. Instead, let's limit the voltage range to a single one, which is in line with the intended use of the regulator. This is done by looking up the minimum and maximum requested voltage specified in devicetree. Signed-off-by: Jonas Andreasson <jonas.andreasson@axis.com> Link: https://patch.msgid.link/20250121-tps-fix-v2-1-50cc4d0f1635@axis.com Signed-off-by: Mark Brown <broonie@kernel.org>
248 lines
6.4 KiB
C
248 lines
6.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2023 Axis Communications AB
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*
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* Driver for Texas Instruments TPS6287x PMIC.
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* Datasheet: https://www.ti.com/lit/ds/symlink/tps62873.pdf
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*/
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#include <linux/err.h>
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#include <linux/i2c.h>
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#include <linux/mod_devicetable.h>
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#include <linux/module.h>
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#include <linux/regmap.h>
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#include <linux/regulator/of_regulator.h>
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#include <linux/regulator/machine.h>
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#include <linux/regulator/driver.h>
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#include <linux/bitfield.h>
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#include <linux/linear_range.h>
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#define TPS6287X_VSET 0x00
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#define TPS6287X_CTRL1 0x01
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#define TPS6287X_CTRL1_VRAMP GENMASK(1, 0)
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#define TPS6287X_CTRL1_FPWMEN BIT(4)
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#define TPS6287X_CTRL1_SWEN BIT(5)
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#define TPS6287X_CTRL2 0x02
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#define TPS6287X_CTRL2_VRANGE GENMASK(3, 2)
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#define TPS6287X_CTRL3 0x03
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#define TPS6287X_STATUS 0x04
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static const struct regmap_config tps6287x_regmap_config = {
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.reg_bits = 8,
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.val_bits = 8,
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.max_register = TPS6287X_STATUS,
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};
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static const struct linear_range tps6287x_voltage_ranges[] = {
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LINEAR_RANGE(400000, 0, 0xFF, 1250),
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LINEAR_RANGE(400000, 0, 0xFF, 2500),
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LINEAR_RANGE(400000, 0, 0xFF, 5000),
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LINEAR_RANGE(800000, 0, 0xFF, 10000),
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};
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static const unsigned int tps6287x_voltage_range_sel[] = {
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0x0, 0x1, 0x2, 0x3
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};
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static const unsigned int tps6287x_voltage_range_prefix[] = {
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0x000, 0x100, 0x200, 0x300
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};
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static const unsigned int tps6287x_ramp_table[] = {
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10000, 5000, 1250, 500
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};
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struct tps6287x_reg_data {
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int range;
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};
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static int tps6287x_best_range(struct regulator_config *config, const struct regulator_desc *desc)
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{
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const struct linear_range *r;
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int i;
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if (!config->init_data->constraints.apply_uV)
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return -1;
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for (i = 0; i < desc->n_linear_ranges; i++) {
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r = &desc->linear_ranges[i];
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if (r->min <= config->init_data->constraints.min_uV &&
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config->init_data->constraints.max_uV <= linear_range_get_max_value(r))
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return i;
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}
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return -1;
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}
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static int tps6287x_set_mode(struct regulator_dev *rdev, unsigned int mode)
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{
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unsigned int val;
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switch (mode) {
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case REGULATOR_MODE_NORMAL:
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val = 0;
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break;
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case REGULATOR_MODE_FAST:
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val = TPS6287X_CTRL1_FPWMEN;
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break;
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default:
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return -EINVAL;
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}
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return regmap_update_bits(rdev->regmap, TPS6287X_CTRL1,
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TPS6287X_CTRL1_FPWMEN, val);
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}
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static unsigned int tps6287x_get_mode(struct regulator_dev *rdev)
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{
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unsigned int val;
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int ret;
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ret = regmap_read(rdev->regmap, TPS6287X_CTRL1, &val);
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if (ret < 0)
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return 0;
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return (val & TPS6287X_CTRL1_FPWMEN) ? REGULATOR_MODE_FAST :
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REGULATOR_MODE_NORMAL;
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}
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static unsigned int tps6287x_of_map_mode(unsigned int mode)
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{
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switch (mode) {
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case REGULATOR_MODE_NORMAL:
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case REGULATOR_MODE_FAST:
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return mode;
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default:
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return REGULATOR_MODE_INVALID;
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}
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}
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static int tps6287x_map_voltage(struct regulator_dev *rdev, int min_uV, int max_uV)
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{
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struct tps6287x_reg_data *data = (struct tps6287x_reg_data *)rdev->reg_data;
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struct linear_range selected_range;
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int selector, voltage;
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if (!data || data->range == -1)
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return regulator_map_voltage_pickable_linear_range(rdev, min_uV, max_uV);
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selected_range = rdev->desc->linear_ranges[data->range];
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selector = DIV_ROUND_UP(min_uV - selected_range.min, selected_range.step);
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if (selector < selected_range.min_sel || selector > selected_range.max_sel)
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return -EINVAL;
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selector |= tps6287x_voltage_range_prefix[data->range];
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voltage = rdev->desc->ops->list_voltage(rdev, selector);
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if (voltage < min_uV || voltage > max_uV)
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return -EINVAL;
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return selector;
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}
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static const struct regulator_ops tps6287x_regulator_ops = {
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.enable = regulator_enable_regmap,
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.disable = regulator_disable_regmap,
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.set_mode = tps6287x_set_mode,
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.get_mode = tps6287x_get_mode,
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.is_enabled = regulator_is_enabled_regmap,
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.get_voltage_sel = regulator_get_voltage_sel_pickable_regmap,
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.set_voltage_sel = regulator_set_voltage_sel_pickable_regmap,
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.list_voltage = regulator_list_voltage_pickable_linear_range,
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.map_voltage = tps6287x_map_voltage,
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.set_ramp_delay = regulator_set_ramp_delay_regmap,
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};
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static const struct regulator_desc tps6287x_reg = {
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.name = "tps6287x",
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.owner = THIS_MODULE,
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.ops = &tps6287x_regulator_ops,
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.of_map_mode = tps6287x_of_map_mode,
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.type = REGULATOR_VOLTAGE,
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.enable_reg = TPS6287X_CTRL1,
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.enable_mask = TPS6287X_CTRL1_SWEN,
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.vsel_reg = TPS6287X_VSET,
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.vsel_mask = 0xFF,
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.vsel_range_reg = TPS6287X_CTRL2,
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.vsel_range_mask = TPS6287X_CTRL2_VRANGE,
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.range_applied_by_vsel = true,
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.ramp_reg = TPS6287X_CTRL1,
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.ramp_mask = TPS6287X_CTRL1_VRAMP,
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.ramp_delay_table = tps6287x_ramp_table,
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.n_ramp_values = ARRAY_SIZE(tps6287x_ramp_table),
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.n_voltages = 256 * ARRAY_SIZE(tps6287x_voltage_ranges),
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.linear_ranges = tps6287x_voltage_ranges,
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.n_linear_ranges = ARRAY_SIZE(tps6287x_voltage_ranges),
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.linear_range_selectors_bitfield = tps6287x_voltage_range_sel,
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};
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static int tps6287x_i2c_probe(struct i2c_client *i2c)
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{
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struct device *dev = &i2c->dev;
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struct regulator_config config = {};
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struct tps6287x_reg_data *reg_data;
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struct regulator_dev *rdev;
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reg_data = devm_kzalloc(dev, sizeof(struct tps6287x_reg_data), GFP_KERNEL);
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if (!reg_data)
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return -ENOMEM;
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config.regmap = devm_regmap_init_i2c(i2c, &tps6287x_regmap_config);
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if (IS_ERR(config.regmap)) {
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dev_err(dev, "Failed to init i2c\n");
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return PTR_ERR(config.regmap);
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}
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config.dev = dev;
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config.of_node = dev->of_node;
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config.init_data = of_get_regulator_init_data(dev, dev->of_node,
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&tps6287x_reg);
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reg_data->range = tps6287x_best_range(&config, &tps6287x_reg);
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rdev = devm_regulator_register(dev, &tps6287x_reg, &config);
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if (IS_ERR(rdev)) {
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dev_err(dev, "Failed to register regulator\n");
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return PTR_ERR(rdev);
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}
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rdev->reg_data = (void *)reg_data;
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dev_dbg(dev, "Probed regulator\n");
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return 0;
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}
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static const struct of_device_id tps6287x_dt_ids[] = {
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{ .compatible = "ti,tps62870", },
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{ .compatible = "ti,tps62871", },
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{ .compatible = "ti,tps62872", },
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{ .compatible = "ti,tps62873", },
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{ }
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};
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MODULE_DEVICE_TABLE(of, tps6287x_dt_ids);
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static const struct i2c_device_id tps6287x_i2c_id[] = {
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{ "tps62870" },
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{ "tps62871" },
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{ "tps62872" },
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{ "tps62873" },
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{}
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};
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MODULE_DEVICE_TABLE(i2c, tps6287x_i2c_id);
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static struct i2c_driver tps6287x_regulator_driver = {
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.driver = {
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.name = "tps6287x",
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.of_match_table = tps6287x_dt_ids,
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},
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.probe = tps6287x_i2c_probe,
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.id_table = tps6287x_i2c_id,
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};
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module_i2c_driver(tps6287x_regulator_driver);
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MODULE_AUTHOR("Mårten Lindahl <marten.lindahl@axis.com>");
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MODULE_DESCRIPTION("Regulator driver for TI TPS6287X PMIC");
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MODULE_LICENSE("GPL");
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