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linux/drivers/iio/adc/mcp3422.c
Angelo Compagnucci 6be72b9067 iio: adc: mcp3422: Checking for error on probe 
Some part of the configuration are not touched after the probe
and if something goes wrong on writing the initial one,
the chip will misbehave.
Adding an error checking ensures that the inital configuration will
be written correctly. Moreover ensures that a sensible configuration
will be saved in driver data and used subsequently as intended.

Signed-off-by: Angelo Compagnucci <angelo.compagnucci@gmail.com>
Reported-by: Maarten Brock <m.brock@vanmierlo.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
2017-07-02 10:24:52 +01:00

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/*
* mcp3422.c - driver for the Microchip mcp3421/2/3/4/5/6/7/8 chip family
*
* Copyright (C) 2013, Angelo Compagnucci
* Author: Angelo Compagnucci <angelo.compagnucci@gmail.com>
*
* Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/22088b.pdf
* http://ww1.microchip.com/downloads/en/DeviceDoc/22226a.pdf
* http://ww1.microchip.com/downloads/en/DeviceDoc/22072b.pdf
*
* This driver exports the value of analog input voltage to sysfs, the
* voltage unit is nV.
*
* 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/err.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/sysfs.h>
#include <linux/of.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
/* Masks */
#define MCP3422_CHANNEL_MASK 0x60
#define MCP3422_PGA_MASK 0x03
#define MCP3422_SRATE_MASK 0x0C
#define MCP3422_SRATE_240 0x0
#define MCP3422_SRATE_60 0x1
#define MCP3422_SRATE_15 0x2
#define MCP3422_SRATE_3 0x3
#define MCP3422_PGA_1 0
#define MCP3422_PGA_2 1
#define MCP3422_PGA_4 2
#define MCP3422_PGA_8 3
#define MCP3422_CONT_SAMPLING 0x10
#define MCP3422_CHANNEL(config) (((config) & MCP3422_CHANNEL_MASK) >> 5)
#define MCP3422_PGA(config) ((config) & MCP3422_PGA_MASK)
#define MCP3422_SAMPLE_RATE(config) (((config) & MCP3422_SRATE_MASK) >> 2)
#define MCP3422_CHANNEL_VALUE(value) (((value) << 5) & MCP3422_CHANNEL_MASK)
#define MCP3422_PGA_VALUE(value) ((value) & MCP3422_PGA_MASK)
#define MCP3422_SAMPLE_RATE_VALUE(value) ((value << 2) & MCP3422_SRATE_MASK)
#define MCP3422_CHAN(_index) \
{ \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = _index, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
| BIT(IIO_CHAN_INFO_SCALE), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
}
static const int mcp3422_scales[4][4] = {
{ 1000000, 500000, 250000, 125000 },
{ 250000, 125000, 62500, 31250 },
{ 62500, 31250, 15625, 7812 },
{ 15625, 7812, 3906, 1953 } };
/* Constant msleep times for data acquisitions */
static const int mcp3422_read_times[4] = {
[MCP3422_SRATE_240] = 1000 / 240,
[MCP3422_SRATE_60] = 1000 / 60,
[MCP3422_SRATE_15] = 1000 / 15,
[MCP3422_SRATE_3] = 1000 / 3 };
/* sample rates to integer conversion table */
static const int mcp3422_sample_rates[4] = {
[MCP3422_SRATE_240] = 240,
[MCP3422_SRATE_60] = 60,
[MCP3422_SRATE_15] = 15,
[MCP3422_SRATE_3] = 3 };
/* sample rates to sign extension table */
static const int mcp3422_sign_extend[4] = {
[MCP3422_SRATE_240] = 11,
[MCP3422_SRATE_60] = 13,
[MCP3422_SRATE_15] = 15,
[MCP3422_SRATE_3] = 17 };
/* Client data (each client gets its own) */
struct mcp3422 {
struct i2c_client *i2c;
u8 id;
u8 config;
u8 pga[4];
struct mutex lock;
};
static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig)
{
int ret;
mutex_lock(&adc->lock);
ret = i2c_master_send(adc->i2c, &newconfig, 1);
if (ret > 0) {
adc->config = newconfig;
ret = 0;
}
mutex_unlock(&adc->lock);
return ret;
}
static int mcp3422_read(struct mcp3422 *adc, int *value, u8 *config)
{
int ret = 0;
u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
u8 buf[4] = {0, 0, 0, 0};
u32 temp;
if (sample_rate == MCP3422_SRATE_3) {
ret = i2c_master_recv(adc->i2c, buf, 4);
temp = buf[0] << 16 | buf[1] << 8 | buf[2];
*config = buf[3];
} else {
ret = i2c_master_recv(adc->i2c, buf, 3);
temp = buf[0] << 8 | buf[1];
*config = buf[2];
}
*value = sign_extend32(temp, mcp3422_sign_extend[sample_rate]);
return ret;
}
static int mcp3422_read_channel(struct mcp3422 *adc,
struct iio_chan_spec const *channel, int *value)
{
int ret;
u8 config;
u8 req_channel = channel->channel;
if (req_channel != MCP3422_CHANNEL(adc->config)) {
config = adc->config;
config &= ~MCP3422_CHANNEL_MASK;
config |= MCP3422_CHANNEL_VALUE(req_channel);
config &= ~MCP3422_PGA_MASK;
config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
ret = mcp3422_update_config(adc, config);
if (ret < 0)
return ret;
msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
}
return mcp3422_read(adc, value, &config);
}
static int mcp3422_read_raw(struct iio_dev *iio,
struct iio_chan_spec const *channel, int *val1,
int *val2, long mask)
{
struct mcp3422 *adc = iio_priv(iio);
int err;
u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
u8 pga = MCP3422_PGA(adc->config);
switch (mask) {
case IIO_CHAN_INFO_RAW:
err = mcp3422_read_channel(adc, channel, val1);
if (err < 0)
return -EINVAL;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*val1 = 0;
*val2 = mcp3422_scales[sample_rate][pga];
return IIO_VAL_INT_PLUS_NANO;
case IIO_CHAN_INFO_SAMP_FREQ:
*val1 = mcp3422_sample_rates[MCP3422_SAMPLE_RATE(adc->config)];
return IIO_VAL_INT;
default:
break;
}
return -EINVAL;
}
static int mcp3422_write_raw(struct iio_dev *iio,
struct iio_chan_spec const *channel, int val1,
int val2, long mask)
{
struct mcp3422 *adc = iio_priv(iio);
u8 temp;
u8 config = adc->config;
u8 req_channel = channel->channel;
u8 sample_rate = MCP3422_SAMPLE_RATE(config);
u8 i;
switch (mask) {
case IIO_CHAN_INFO_SCALE:
if (val1 != 0)
return -EINVAL;
for (i = 0; i < ARRAY_SIZE(mcp3422_scales[0]); i++) {
if (val2 == mcp3422_scales[sample_rate][i]) {
adc->pga[req_channel] = i;
config &= ~MCP3422_CHANNEL_MASK;
config |= MCP3422_CHANNEL_VALUE(req_channel);
config &= ~MCP3422_PGA_MASK;
config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
return mcp3422_update_config(adc, config);
}
}
return -EINVAL;
case IIO_CHAN_INFO_SAMP_FREQ:
switch (val1) {
case 240:
temp = MCP3422_SRATE_240;
break;
case 60:
temp = MCP3422_SRATE_60;
break;
case 15:
temp = MCP3422_SRATE_15;
break;
case 3:
if (adc->id > 4)
return -EINVAL;
temp = MCP3422_SRATE_3;
break;
default:
return -EINVAL;
}
config &= ~MCP3422_CHANNEL_MASK;
config |= MCP3422_CHANNEL_VALUE(req_channel);
config &= ~MCP3422_SRATE_MASK;
config |= MCP3422_SAMPLE_RATE_VALUE(temp);
return mcp3422_update_config(adc, config);
default:
break;
}
return -EINVAL;
}
static int mcp3422_write_raw_get_fmt(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, long mask)
{
switch (mask) {
case IIO_CHAN_INFO_SCALE:
return IIO_VAL_INT_PLUS_NANO;
case IIO_CHAN_INFO_SAMP_FREQ:
return IIO_VAL_INT_PLUS_MICRO;
default:
return -EINVAL;
}
}
static ssize_t mcp3422_show_samp_freqs(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
if (adc->id > 4)
return sprintf(buf, "240 60 15\n");
return sprintf(buf, "240 60 15 3\n");
}
static ssize_t mcp3422_show_scales(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
return sprintf(buf, "0.%09u 0.%09u 0.%09u 0.%09u\n",
mcp3422_scales[sample_rate][0],
mcp3422_scales[sample_rate][1],
mcp3422_scales[sample_rate][2],
mcp3422_scales[sample_rate][3]);
}
static IIO_DEVICE_ATTR(sampling_frequency_available, S_IRUGO,
mcp3422_show_samp_freqs, NULL, 0);
static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
mcp3422_show_scales, NULL, 0);
static struct attribute *mcp3422_attributes[] = {
&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
&iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
NULL,
};
static const struct attribute_group mcp3422_attribute_group = {
.attrs = mcp3422_attributes,
};
static const struct iio_chan_spec mcp3421_channels[] = {
MCP3422_CHAN(0),
};
static const struct iio_chan_spec mcp3422_channels[] = {
MCP3422_CHAN(0),
MCP3422_CHAN(1),
};
static const struct iio_chan_spec mcp3424_channels[] = {
MCP3422_CHAN(0),
MCP3422_CHAN(1),
MCP3422_CHAN(2),
MCP3422_CHAN(3),
};
static const struct iio_info mcp3422_info = {
.read_raw = mcp3422_read_raw,
.write_raw = mcp3422_write_raw,
.write_raw_get_fmt = mcp3422_write_raw_get_fmt,
.attrs = &mcp3422_attribute_group,
.driver_module = THIS_MODULE,
};
static int mcp3422_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct iio_dev *indio_dev;
struct mcp3422 *adc;
int err;
u8 config;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
return -EOPNOTSUPP;
indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*adc));
if (!indio_dev)
return -ENOMEM;
adc = iio_priv(indio_dev);
adc->i2c = client;
adc->id = (u8)(id->driver_data);
mutex_init(&adc->lock);
indio_dev->dev.parent = &client->dev;
indio_dev->dev.of_node = client->dev.of_node;
indio_dev->name = dev_name(&client->dev);
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->info = &mcp3422_info;
switch (adc->id) {
case 1:
case 5:
indio_dev->channels = mcp3421_channels;
indio_dev->num_channels = ARRAY_SIZE(mcp3421_channels);
break;
case 2:
case 3:
case 6:
case 7:
indio_dev->channels = mcp3422_channels;
indio_dev->num_channels = ARRAY_SIZE(mcp3422_channels);
break;
case 4:
case 8:
indio_dev->channels = mcp3424_channels;
indio_dev->num_channels = ARRAY_SIZE(mcp3424_channels);
break;
}
/* meaningful default configuration */
config = (MCP3422_CONT_SAMPLING
| MCP3422_CHANNEL_VALUE(0)
| MCP3422_PGA_VALUE(MCP3422_PGA_1)
| MCP3422_SAMPLE_RATE_VALUE(MCP3422_SRATE_240));
err = mcp3422_update_config(adc, config);
if (err < 0)
return err;
err = devm_iio_device_register(&client->dev, indio_dev);
if (err < 0)
return err;
i2c_set_clientdata(client, indio_dev);
return 0;
}
static const struct i2c_device_id mcp3422_id[] = {
{ "mcp3421", 1 },
{ "mcp3422", 2 },
{ "mcp3423", 3 },
{ "mcp3424", 4 },
{ "mcp3425", 5 },
{ "mcp3426", 6 },
{ "mcp3427", 7 },
{ "mcp3428", 8 },
{ }
};
MODULE_DEVICE_TABLE(i2c, mcp3422_id);
#ifdef CONFIG_OF
static const struct of_device_id mcp3422_of_match[] = {
{ .compatible = "mcp3422" },
{ }
};
MODULE_DEVICE_TABLE(of, mcp3422_of_match);
#endif
static struct i2c_driver mcp3422_driver = {
.driver = {
.name = "mcp3422",
.of_match_table = of_match_ptr(mcp3422_of_match),
},
.probe = mcp3422_probe,
.id_table = mcp3422_id,
};
module_i2c_driver(mcp3422_driver);
MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
MODULE_DESCRIPTION("Microchip mcp3421/2/3/4/5/6/7/8 driver");
MODULE_LICENSE("GPL v2");
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