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// SPDX-License-Identifier: GPL-2.0
/*
* MAX77705 voltage and current hwmon driver.
*
* Copyright (C) 2025 Dzmitry Sankouski <dsankouski@gmail.com>
*/
#include <linux/err.h>
#include <linux/hwmon-sysfs.h>
#include <linux/hwmon.h>
#include <linux/kernel.h>
#include <linux/mfd/max77705-private.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
struct channel_desc {
u8 reg;
u8 avg_reg;
const char *const label;
// register resolution. nano Volts for voltage, nano Amperes for current
u32 resolution;
};
static const struct channel_desc current_channel_desc[] = {
{
.reg = IIN_REG,
.label = "IIN_REG",
.resolution = 125000
},
{
.reg = ISYS_REG,
.avg_reg = AVGISYS_REG,
.label = "ISYS_REG",
.resolution = 312500
}
};
static const struct channel_desc voltage_channel_desc[] = {
{
.reg = VBYP_REG,
.label = "VBYP_REG",
.resolution = 427246
},
{
.reg = VSYS_REG,
.label = "VSYS_REG",
.resolution = 156250
}
};
static int max77705_read_and_convert(struct regmap *regmap, u8 reg, u32 res,
bool is_signed, long *val)
{
int ret;
u32 regval;
ret = regmap_read(regmap, reg, ®val);
if (ret < 0)
return ret;
if (is_signed)
*val = mult_frac((long)sign_extend32(regval, 15), res, 1000000);
else
*val = mult_frac((long)regval, res, 1000000);
return 0;
}
static umode_t max77705_is_visible(const void *data,
enum hwmon_sensor_types type,
u32 attr, int channel)
{
switch (type) {
case hwmon_in:
switch (attr) {
case hwmon_in_input:
case hwmon_in_label:
return 0444;
default:
break;
}
break;
case hwmon_curr:
switch (attr) {
case hwmon_curr_input:
case hwmon_in_label:
return 0444;
case hwmon_curr_average:
if (current_channel_desc[channel].avg_reg)
return 0444;
break;
default:
break;
}
break;
default:
break;
}
return 0;
}
static int max77705_read_string(struct device *dev, enum hwmon_sensor_types type, u32 attr,
int channel, const char **buf)
{
switch (type) {
case hwmon_curr:
switch (attr) {
case hwmon_in_label:
*buf = current_channel_desc[channel].label;
return 0;
default:
return -EOPNOTSUPP;
}
case hwmon_in:
switch (attr) {
case hwmon_in_label:
*buf = voltage_channel_desc[channel].label;
return 0;
default:
return -EOPNOTSUPP;
}
default:
return -EOPNOTSUPP;
}
}
static int max77705_read(struct device *dev, enum hwmon_sensor_types type,
u32 attr, int channel, long *val)
{
struct regmap *regmap = dev_get_drvdata(dev);
u8 reg;
u32 res;
switch (type) {
case hwmon_curr:
switch (attr) {
case hwmon_curr_input:
reg = current_channel_desc[channel].reg;
res = current_channel_desc[channel].resolution;
return max77705_read_and_convert(regmap, reg, res, true, val);
case hwmon_curr_average:
reg = current_channel_desc[channel].avg_reg;
res = current_channel_desc[channel].resolution;
return max77705_read_and_convert(regmap, reg, res, true, val);
default:
return -EOPNOTSUPP;
}
case hwmon_in:
switch (attr) {
case hwmon_in_input:
reg = voltage_channel_desc[channel].reg;
res = voltage_channel_desc[channel].resolution;
return max77705_read_and_convert(regmap, reg, res, false, val);
default:
return -EOPNOTSUPP;
}
default:
return -EOPNOTSUPP;
}
return 0;
}
static const struct hwmon_ops max77705_hwmon_ops = {
.is_visible = max77705_is_visible,
.read = max77705_read,
.read_string = max77705_read_string,
};
static const struct hwmon_channel_info *max77705_info[] = {
HWMON_CHANNEL_INFO(in,
HWMON_I_INPUT | HWMON_I_LABEL,
HWMON_I_INPUT | HWMON_I_LABEL
),
HWMON_CHANNEL_INFO(curr,
HWMON_C_INPUT | HWMON_C_LABEL,
HWMON_C_INPUT | HWMON_C_AVERAGE | HWMON_C_LABEL
),
NULL
};
static const struct hwmon_chip_info max77705_chip_info = {
.ops = &max77705_hwmon_ops,
.info = max77705_info,
};
static int max77705_hwmon_probe(struct platform_device *pdev)
{
struct device *hwmon_dev;
struct regmap *regmap;
regmap = dev_get_regmap(pdev->dev.parent, NULL);
if (!regmap)
return -ENODEV;
hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev, "max77705", regmap,
&max77705_chip_info, NULL);
if (IS_ERR(hwmon_dev))
return dev_err_probe(&pdev->dev, PTR_ERR(hwmon_dev),
"Unable to register hwmon device\n");
return 0;
};
static struct platform_driver max77705_hwmon_driver = {
.driver = {
.name = "max77705-hwmon",
},
.probe = max77705_hwmon_probe,
};
module_platform_driver(max77705_hwmon_driver);
MODULE_AUTHOR("Dzmitry Sankouski <dsankouski@gmail.com>");
MODULE_DESCRIPTION("MAX77705 monitor driver");
MODULE_LICENSE("GPL");
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