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linux/drivers/hwmon/max197.c
Uwe Kleine-König 19eae13a89 hwmon: (max197) Convert to platform remove callback returning void 
The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.
To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new() which already returns void. Eventually after all drivers
are converted, .remove_new() is renamed to .remove().

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230918085951.1234172-10-u.kleine-koenig@pengutronix.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2023-10-27 07:27:24 -07:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Maxim MAX197 A/D Converter driver
*
* Copyright (c) 2012 Savoir-faire Linux Inc.
* Vivien Didelot <vivien.didelot@savoirfairelinux.com>
*
* For further information, see the Documentation/hwmon/max197.rst file.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/sysfs.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/platform_device.h>
#include <linux/platform_data/max197.h>
#define MAX199_LIMIT 4000 /* 4V */
#define MAX197_LIMIT 10000 /* 10V */
#define MAX197_NUM_CH 8 /* 8 Analog Input Channels */
/* Control byte format */
#define MAX197_BIP (1 << 3) /* Bipolarity */
#define MAX197_RNG (1 << 4) /* Full range */
#define MAX197_SCALE 12207 /* Scale coefficient for raw data */
/* List of supported chips */
enum max197_chips { max197, max199 };
/**
* struct max197_data - device instance specific data
* @pdata: Platform data.
* @hwmon_dev: The hwmon device.
* @lock: Read/Write mutex.
* @limit: Max range value (10V for MAX197, 4V for MAX199).
* @scale: Need to scale.
* @ctrl_bytes: Channels control byte.
*/
struct max197_data {
struct max197_platform_data *pdata;
struct device *hwmon_dev;
struct mutex lock;
int limit;
bool scale;
u8 ctrl_bytes[MAX197_NUM_CH];
};
static inline void max197_set_unipolarity(struct max197_data *data, int channel)
{
data->ctrl_bytes[channel] &= ~MAX197_BIP;
}
static inline void max197_set_bipolarity(struct max197_data *data, int channel)
{
data->ctrl_bytes[channel] |= MAX197_BIP;
}
static inline void max197_set_half_range(struct max197_data *data, int channel)
{
data->ctrl_bytes[channel] &= ~MAX197_RNG;
}
static inline void max197_set_full_range(struct max197_data *data, int channel)
{
data->ctrl_bytes[channel] |= MAX197_RNG;
}
static inline bool max197_is_bipolar(struct max197_data *data, int channel)
{
return data->ctrl_bytes[channel] & MAX197_BIP;
}
static inline bool max197_is_full_range(struct max197_data *data, int channel)
{
return data->ctrl_bytes[channel] & MAX197_RNG;
}
/* Function called on read access on in{0,1,2,3,4,5,6,7}_{min,max} */
static ssize_t max197_show_range(struct device *dev,
struct device_attribute *devattr, char *buf)
{
struct max197_data *data = dev_get_drvdata(dev);
struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
int channel = attr->index;
bool is_min = attr->nr;
int range;
if (mutex_lock_interruptible(&data->lock))
return -ERESTARTSYS;
range = max197_is_full_range(data, channel) ?
data->limit : data->limit / 2;
if (is_min) {
if (max197_is_bipolar(data, channel))
range = -range;
else
range = 0;
}
mutex_unlock(&data->lock);
return sprintf(buf, "%d\n", range);
}
/* Function called on write access on in{0,1,2,3,4,5,6,7}_{min,max} */
static ssize_t max197_store_range(struct device *dev,
struct device_attribute *devattr,
const char *buf, size_t count)
{
struct max197_data *data = dev_get_drvdata(dev);
struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
int channel = attr->index;
bool is_min = attr->nr;
long value;
int half = data->limit / 2;
int full = data->limit;
if (kstrtol(buf, 10, &value))
return -EINVAL;
if (is_min) {
if (value <= -full)
value = -full;
else if (value < 0)
value = -half;
else
value = 0;
} else {
if (value >= full)
value = full;
else
value = half;
}
if (mutex_lock_interruptible(&data->lock))
return -ERESTARTSYS;
if (value == 0) {
/* We can deduce only the polarity */
max197_set_unipolarity(data, channel);
} else if (value == -half) {
max197_set_bipolarity(data, channel);
max197_set_half_range(data, channel);
} else if (value == -full) {
max197_set_bipolarity(data, channel);
max197_set_full_range(data, channel);
} else if (value == half) {
/* We can deduce only the range */
max197_set_half_range(data, channel);
} else if (value == full) {
/* We can deduce only the range */
max197_set_full_range(data, channel);
}
mutex_unlock(&data->lock);
return count;
}
/* Function called on read access on in{0,1,2,3,4,5,6,7}_input */
static ssize_t max197_show_input(struct device *dev,
struct device_attribute *devattr,
char *buf)
{
struct max197_data *data = dev_get_drvdata(dev);
struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
int channel = attr->index;
s32 value;
int ret;
if (mutex_lock_interruptible(&data->lock))
return -ERESTARTSYS;
ret = data->pdata->convert(data->ctrl_bytes[channel]);
if (ret < 0) {
dev_err(dev, "conversion failed\n");
goto unlock;
}
value = ret;
/*
* Coefficient to apply on raw value.
* See Table 1. Full Scale and Zero Scale in the MAX197 datasheet.
*/
if (data->scale) {
value *= MAX197_SCALE;
if (max197_is_full_range(data, channel))
value *= 2;
value /= 10000;
}
ret = sprintf(buf, "%d\n", value);
unlock:
mutex_unlock(&data->lock);
return ret;
}
static ssize_t name_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct platform_device *pdev = to_platform_device(dev);
return sprintf(buf, "%s\n", pdev->name);
}
#define MAX197_SENSOR_DEVICE_ATTR_CH(chan) \
static SENSOR_DEVICE_ATTR(in##chan##_input, S_IRUGO, \
max197_show_input, NULL, chan); \
static SENSOR_DEVICE_ATTR_2(in##chan##_min, S_IRUGO | S_IWUSR, \
max197_show_range, \
max197_store_range, \
true, chan); \
static SENSOR_DEVICE_ATTR_2(in##chan##_max, S_IRUGO | S_IWUSR, \
max197_show_range, \
max197_store_range, \
false, chan)
#define MAX197_SENSOR_DEV_ATTR_IN(chan) \
&sensor_dev_attr_in##chan##_input.dev_attr.attr, \
&sensor_dev_attr_in##chan##_max.dev_attr.attr, \
&sensor_dev_attr_in##chan##_min.dev_attr.attr
static DEVICE_ATTR_RO(name);
MAX197_SENSOR_DEVICE_ATTR_CH(0);
MAX197_SENSOR_DEVICE_ATTR_CH(1);
MAX197_SENSOR_DEVICE_ATTR_CH(2);
MAX197_SENSOR_DEVICE_ATTR_CH(3);
MAX197_SENSOR_DEVICE_ATTR_CH(4);
MAX197_SENSOR_DEVICE_ATTR_CH(5);
MAX197_SENSOR_DEVICE_ATTR_CH(6);
MAX197_SENSOR_DEVICE_ATTR_CH(7);
static const struct attribute_group max197_sysfs_group = {
.attrs = (struct attribute *[]) {
&dev_attr_name.attr,
MAX197_SENSOR_DEV_ATTR_IN(0),
MAX197_SENSOR_DEV_ATTR_IN(1),
MAX197_SENSOR_DEV_ATTR_IN(2),
MAX197_SENSOR_DEV_ATTR_IN(3),
MAX197_SENSOR_DEV_ATTR_IN(4),
MAX197_SENSOR_DEV_ATTR_IN(5),
MAX197_SENSOR_DEV_ATTR_IN(6),
MAX197_SENSOR_DEV_ATTR_IN(7),
NULL
},
};
static int max197_probe(struct platform_device *pdev)
{
int ch, ret;
struct max197_data *data;
struct max197_platform_data *pdata = dev_get_platdata(&pdev->dev);
enum max197_chips chip = platform_get_device_id(pdev)->driver_data;
if (pdata == NULL) {
dev_err(&pdev->dev, "no platform data supplied\n");
return -EINVAL;
}
if (pdata->convert == NULL) {
dev_err(&pdev->dev, "no convert function supplied\n");
return -EINVAL;
}
data = devm_kzalloc(&pdev->dev, sizeof(struct max197_data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->pdata = pdata;
mutex_init(&data->lock);
if (chip == max197) {
data->limit = MAX197_LIMIT;
data->scale = true;
} else {
data->limit = MAX199_LIMIT;
data->scale = false;
}
for (ch = 0; ch < MAX197_NUM_CH; ch++)
data->ctrl_bytes[ch] = (u8) ch;
platform_set_drvdata(pdev, data);
ret = sysfs_create_group(&pdev->dev.kobj, &max197_sysfs_group);
if (ret) {
dev_err(&pdev->dev, "sysfs create group failed\n");
return ret;
}
data->hwmon_dev = hwmon_device_register(&pdev->dev);
if (IS_ERR(data->hwmon_dev)) {
ret = PTR_ERR(data->hwmon_dev);
dev_err(&pdev->dev, "hwmon device register failed\n");
goto error;
}
return 0;
error:
sysfs_remove_group(&pdev->dev.kobj, &max197_sysfs_group);
return ret;
}
static void max197_remove(struct platform_device *pdev)
{
struct max197_data *data = platform_get_drvdata(pdev);
hwmon_device_unregister(data->hwmon_dev);
sysfs_remove_group(&pdev->dev.kobj, &max197_sysfs_group);
}
static const struct platform_device_id max197_device_ids[] = {
{ "max197", max197 },
{ "max199", max199 },
{ }
};
MODULE_DEVICE_TABLE(platform, max197_device_ids);
static struct platform_driver max197_driver = {
.driver = {
.name = "max197",
},
.probe = max197_probe,
.remove_new = max197_remove,
.id_table = max197_device_ids,
};
module_platform_driver(max197_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Savoir-faire Linux Inc. <kernel@savoirfairelinux.com>");
MODULE_DESCRIPTION("Maxim MAX197 A/D Converter driver");
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