[PATCH v6 2/3] hwmon: (ads7871) Convert to hwmon_device_register_with_info

Tabrez Ahmed
2026-05-02T02:09:00Z

Convert the ads7871 driver from the legacy hwmon_device_register() to the
modern hwmon_device_register_with_info() API. This migration simplifies
the driver by using the structured hwmon_channel_info approach and
prepares the codebase for the transition to a shared DMA-safe buffer.
While at it, fix checkpatch violations.

Signed-off-by: Tabrez Ahmed <tabreztalks@gmail.com>
---
drivers/hwmon/ads7871.c | 75 ++++++++++++++++++++++-------------------
1 file changed, 40 insertions(+), 35 deletions(-)

diff --git a/drivers/hwmon/ads7871.c b/drivers/hwmon/ads7871.c
index 52584bb77ffb7..8ffcc4c823a60 100644
--- a/drivers/hwmon/ads7871.c
+++ b/drivers/hwmon/ads7871.c
@@ -56,7 +56,6 @@
#include <linux/init.h>
#include <linux/spi/spi.h>
#include <linux/hwmon.h>
-#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/delay.h>

@@ -65,6 +64,16 @@ struct ads7871_data {
struct spi_device *spi;
};

+static umode_t ads7871_is_visible(const void *data,
+ enum hwmon_sensor_types type,
+ u32 attr, int channel)
+{
+ if (type == hwmon_in && attr == hwmon_in_input)
+ return 0444;
+
+ return 0;
+}
+
static int ads7871_read_reg8(struct spi_device *spi, int reg)
{
int ret;
@@ -88,19 +97,20 @@ static int ads7871_read_reg16(struct spi_device *spi, int reg)
static int ads7871_write_reg8(struct spi_device *spi, int reg, u8 val)
{
u8 tmp[2] = {reg, val};
+
return spi_write(spi, tmp, sizeof(tmp));
}

-static ssize_t voltage_show(struct device *dev, struct device_attribute *da,
- char *buf)
+static int ads7871_read(struct device *dev, enum hwmon_sensor_types type,
+ u32 attr, int channel, long *val)
{
struct ads7871_data *pdata = dev_get_drvdata(dev);
struct spi_device *spi = pdata->spi;
- struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
- int ret, val, i = 0;
- uint8_t channel, mux_cnv;
+ int ret, raw_val, i = 0;
+ u8 mux_cnv;

- channel = attr->index;
+ if (type != hwmon_in || attr != hwmon_in_input)
+ return -EOPNOTSUPP;
/*
* TODO: add support for conversions
* other than single ended with a gain of 1
@@ -130,39 +140,34 @@ static ssize_t voltage_show(struct device *dev, struct device_attribute *da,
}

if (mux_cnv == 0) {
- val = ads7871_read_reg16(spi, REG_LS_BYTE);
- if (val < 0)
- return val;
+ raw_val = ads7871_read_reg16(spi, REG_LS_BYTE);
+ if (raw_val < 0)
+ return raw_val;
+
/*result in volts*10000 = (val/8192)*2.5*10000*/
- val = ((val >> 2) * 25000) / 8192;
- return sysfs_emit(buf, "%d\n", val);
+ *val = ((raw_val >> 2) * 25000) / 8192;
+ return 0;
}

return -ETIMEDOUT;
}

-static SENSOR_DEVICE_ATTR_RO(in0_input, voltage, 0);
-static SENSOR_DEVICE_ATTR_RO(in1_input, voltage, 1);
-static SENSOR_DEVICE_ATTR_RO(in2_input, voltage, 2);
-static SENSOR_DEVICE_ATTR_RO(in3_input, voltage, 3);
-static SENSOR_DEVICE_ATTR_RO(in4_input, voltage, 4);
-static SENSOR_DEVICE_ATTR_RO(in5_input, voltage, 5);
-static SENSOR_DEVICE_ATTR_RO(in6_input, voltage, 6);
-static SENSOR_DEVICE_ATTR_RO(in7_input, voltage, 7);
-
-static struct attribute *ads7871_attrs[] = {
- &sensor_dev_attr_in0_input.dev_attr.attr,
- &sensor_dev_attr_in1_input.dev_attr.attr,
- &sensor_dev_attr_in2_input.dev_attr.attr,
- &sensor_dev_attr_in3_input.dev_attr.attr,
- &sensor_dev_attr_in4_input.dev_attr.attr,
- &sensor_dev_attr_in5_input.dev_attr.attr,
- &sensor_dev_attr_in6_input.dev_attr.attr,
- &sensor_dev_attr_in7_input.dev_attr.attr,
+static const struct hwmon_channel_info * const ads7871_info[] = {
+ HWMON_CHANNEL_INFO(in,
+ HWMON_I_INPUT, HWMON_I_INPUT, HWMON_I_INPUT, HWMON_I_INPUT,
+ HWMON_I_INPUT, HWMON_I_INPUT, HWMON_I_INPUT, HWMON_I_INPUT),
NULL
};

-ATTRIBUTE_GROUPS(ads7871);
+static const struct hwmon_ops ads7871_hwmon_ops = {
+ .is_visible = ads7871_is_visible,
+ .read = ads7871_read,
+};
+
+static const struct hwmon_chip_info ads7871_chip_info = {
+ .ops = &ads7871_hwmon_ops,
+ .info = ads7871_info,
+};

static int ads7871_probe(struct spi_device *spi)
{
@@ -197,10 +202,10 @@ static int ads7871_probe(struct spi_device *spi)
return -ENOMEM;

pdata->spi = spi;
-
- hwmon_dev = devm_hwmon_device_register_with_groups(dev, spi->modalias,
- pdata,
- ads7871_groups);
+ hwmon_dev = devm_hwmon_device_register_with_info(dev, spi->modalias,
+ pdata,
+ &ads7871_chip_info,
+ NULL);
return PTR_ERR_OR_ZERO(hwmon_dev);
}

--
2.43.0