linux/drivers/hwmon/mcp3021.c
Julia Lawall 5c2f0dd570 hwmon: (mcp3021) use permission-specific DEVICE_ATTR variants
Use DEVICE_ATTR_RO for read-only attributes. This simplifies the source
code, improves readbility, and reduces the chance of inconsistencies.

The conversion was done automatically using coccinelle. It was validated
by compiling both the old and the new source code and comparing its text,
data, and bss size.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
[groeck: Updated description]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2017-01-02 10:19:45 -08:00

214 lines
5.1 KiB
C

/*
* mcp3021.c - driver for Microchip MCP3021 and MCP3221
*
* Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc.
* Author: Mingkai Hu <Mingkai.hu@freescale.com>
* Reworked by Sven Schuchmann <schuchmann@schleissheimer.de>
* DT support added by Clemens Gruber <clemens.gruber@pqgruber.com>
*
* This driver export the value of analog input voltage to sysfs, the
* voltage unit is mV. Through the sysfs interface, lm-sensors tool
* can also display the input voltage.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/hwmon.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/err.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/of_device.h>
/* Vdd / reference voltage in millivolt */
#define MCP3021_VDD_REF_MAX 5500
#define MCP3021_VDD_REF_MIN 2700
#define MCP3021_VDD_REF_DEFAULT 3300
/* output format */
#define MCP3021_SAR_SHIFT 2
#define MCP3021_SAR_MASK 0x3ff
#define MCP3021_OUTPUT_RES 10 /* 10-bit resolution */
#define MCP3221_SAR_SHIFT 0
#define MCP3221_SAR_MASK 0xfff
#define MCP3221_OUTPUT_RES 12 /* 12-bit resolution */
enum chips {
mcp3021,
mcp3221
};
/*
* Client data (each client gets its own)
*/
struct mcp3021_data {
struct device *hwmon_dev;
u32 vdd; /* supply and reference voltage in millivolt */
u16 sar_shift;
u16 sar_mask;
u8 output_res;
};
static int mcp3021_read16(struct i2c_client *client)
{
struct mcp3021_data *data = i2c_get_clientdata(client);
int ret;
u16 reg;
__be16 buf;
ret = i2c_master_recv(client, (char *)&buf, 2);
if (ret < 0)
return ret;
if (ret != 2)
return -EIO;
/* The output code of the MCP3021 is transmitted with MSB first. */
reg = be16_to_cpu(buf);
/*
* The ten-bit output code is composed of the lower 4-bit of the
* first byte and the upper 6-bit of the second byte.
*/
reg = (reg >> data->sar_shift) & data->sar_mask;
return reg;
}
static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)
{
return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res);
}
static ssize_t in0_input_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct i2c_client *client = to_i2c_client(dev);
struct mcp3021_data *data = i2c_get_clientdata(client);
int reg, in_input;
reg = mcp3021_read16(client);
if (reg < 0)
return reg;
in_input = volts_from_reg(data, reg);
return sprintf(buf, "%d\n", in_input);
}
static DEVICE_ATTR_RO(in0_input);
static int mcp3021_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
int err;
struct mcp3021_data *data = NULL;
struct device_node *np = client->dev.of_node;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
return -ENODEV;
data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
GFP_KERNEL);
if (!data)
return -ENOMEM;
i2c_set_clientdata(client, data);
if (np) {
if (!of_property_read_u32(np, "reference-voltage-microvolt",
&data->vdd))
data->vdd /= 1000;
else
data->vdd = MCP3021_VDD_REF_DEFAULT;
} else {
u32 *pdata = dev_get_platdata(&client->dev);
if (pdata)
data->vdd = *pdata;
else
data->vdd = MCP3021_VDD_REF_DEFAULT;
}
switch (id->driver_data) {
case mcp3021:
data->sar_shift = MCP3021_SAR_SHIFT;
data->sar_mask = MCP3021_SAR_MASK;
data->output_res = MCP3021_OUTPUT_RES;
break;
case mcp3221:
data->sar_shift = MCP3221_SAR_SHIFT;
data->sar_mask = MCP3221_SAR_MASK;
data->output_res = MCP3221_OUTPUT_RES;
break;
}
if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN)
return -EINVAL;
err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr);
if (err)
return err;
data->hwmon_dev = hwmon_device_register(&client->dev);
if (IS_ERR(data->hwmon_dev)) {
err = PTR_ERR(data->hwmon_dev);
goto exit_remove;
}
return 0;
exit_remove:
sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
return err;
}
static int mcp3021_remove(struct i2c_client *client)
{
struct mcp3021_data *data = i2c_get_clientdata(client);
hwmon_device_unregister(data->hwmon_dev);
sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
return 0;
}
static const struct i2c_device_id mcp3021_id[] = {
{ "mcp3021", mcp3021 },
{ "mcp3221", mcp3221 },
{ }
};
MODULE_DEVICE_TABLE(i2c, mcp3021_id);
#ifdef CONFIG_OF
static const struct of_device_id of_mcp3021_match[] = {
{ .compatible = "microchip,mcp3021", .data = (void *)mcp3021 },
{ .compatible = "microchip,mcp3221", .data = (void *)mcp3221 },
{ }
};
MODULE_DEVICE_TABLE(of, of_mcp3021_match);
#endif
static struct i2c_driver mcp3021_driver = {
.driver = {
.name = "mcp3021",
.of_match_table = of_match_ptr(of_mcp3021_match),
},
.probe = mcp3021_probe,
.remove = mcp3021_remove,
.id_table = mcp3021_id,
};
module_i2c_driver(mcp3021_driver);
MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
MODULE_LICENSE("GPL");