linux_dsm_epyc7002/drivers/iio/chemical/vz89x.c
Matt Ranostay bf23cee62d iio: chemical: vz89x hardware i2c workaround
Chipset sometime updates in the middle of a reading causing it
to reset the data pointer, and causing invalid reading of previous data.

We can check for this invalid state by reading MSB of the resistance
reading that is always zero, and by also confirming the VOC_short isn't
zero.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
2015-09-30 18:20:53 +01:00

257 lines
6.1 KiB
C

/*
* vz89x.c - Support for SGX Sensortech MiCS VZ89X VOC sensors
*
* Copyright (C) 2015 Matt Ranostay <mranostay@gmail.com>
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#define VZ89X_REG_MEASUREMENT 0x09
#define VZ89X_REG_MEASUREMENT_SIZE 6
#define VZ89X_VOC_CO2_IDX 0
#define VZ89X_VOC_SHORT_IDX 1
#define VZ89X_VOC_TVOC_IDX 2
#define VZ89X_VOC_RESISTANCE_IDX 3
struct vz89x_data {
struct i2c_client *client;
struct mutex lock;
unsigned long last_update;
u8 buffer[VZ89X_REG_MEASUREMENT_SIZE];
};
static const struct iio_chan_spec vz89x_channels[] = {
{
.type = IIO_CONCENTRATION,
.channel2 = IIO_MOD_CO2,
.modified = 1,
.info_mask_separate =
BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
.address = VZ89X_VOC_CO2_IDX,
},
{
.type = IIO_CONCENTRATION,
.channel2 = IIO_MOD_VOC,
.modified = 1,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
.address = VZ89X_VOC_SHORT_IDX,
.extend_name = "short",
},
{
.type = IIO_CONCENTRATION,
.channel2 = IIO_MOD_VOC,
.modified = 1,
.info_mask_separate =
BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
.address = VZ89X_VOC_TVOC_IDX,
},
{
.type = IIO_RESISTANCE,
.info_mask_separate =
BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
.address = VZ89X_VOC_RESISTANCE_IDX,
},
};
static IIO_CONST_ATTR(in_concentration_co2_scale, "0.00000698689");
static IIO_CONST_ATTR(in_concentration_voc_scale, "0.00000000436681223");
static struct attribute *vz89x_attributes[] = {
&iio_const_attr_in_concentration_co2_scale.dev_attr.attr,
&iio_const_attr_in_concentration_voc_scale.dev_attr.attr,
NULL,
};
static const struct attribute_group vz89x_attrs_group = {
.attrs = vz89x_attributes,
};
/*
* Chipset sometime updates in the middle of a reading causing it to reset the
* data pointer, and causing invalid reading of previous data.
* We can check for this by reading MSB of the resistance reading that is
* always zero, and by also confirming the VOC_short isn't zero.
*/
static int vz89x_measurement_is_valid(struct vz89x_data *data)
{
if (data->buffer[VZ89X_VOC_SHORT_IDX] == 0)
return 1;
return !!(data->buffer[VZ89X_REG_MEASUREMENT_SIZE - 1] > 0);
}
static int vz89x_get_measurement(struct vz89x_data *data)
{
int ret;
int i;
/* sensor can only be polled once a second max per datasheet */
if (!time_after(jiffies, data->last_update + HZ))
return 0;
ret = i2c_smbus_write_word_data(data->client,
VZ89X_REG_MEASUREMENT, 0);
if (ret < 0)
return ret;
for (i = 0; i < VZ89X_REG_MEASUREMENT_SIZE; i++) {
ret = i2c_smbus_read_byte(data->client);
if (ret < 0)
return ret;
data->buffer[i] = ret;
}
ret = vz89x_measurement_is_valid(data);
if (ret)
return -EAGAIN;
data->last_update = jiffies;
return 0;
}
static int vz89x_get_resistance_reading(struct vz89x_data *data)
{
u8 *buf = &data->buffer[VZ89X_VOC_RESISTANCE_IDX];
return buf[0] | (buf[1] << 8);
}
static int vz89x_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int *val,
int *val2, long mask)
{
struct vz89x_data *data = iio_priv(indio_dev);
int ret = -EINVAL;
switch (mask) {
case IIO_CHAN_INFO_RAW:
mutex_lock(&data->lock);
ret = vz89x_get_measurement(data);
mutex_unlock(&data->lock);
if (ret)
return ret;
switch (chan->address) {
case VZ89X_VOC_CO2_IDX:
case VZ89X_VOC_SHORT_IDX:
case VZ89X_VOC_TVOC_IDX:
*val = data->buffer[chan->address];
return IIO_VAL_INT;
case VZ89X_VOC_RESISTANCE_IDX:
*val = vz89x_get_resistance_reading(data);
return IIO_VAL_INT;
default:
return -EINVAL;
}
break;
case IIO_CHAN_INFO_SCALE:
switch (chan->type) {
case IIO_RESISTANCE:
*val = 10;
return IIO_VAL_INT;
default:
return -EINVAL;
}
break;
case IIO_CHAN_INFO_OFFSET:
switch (chan->address) {
case VZ89X_VOC_CO2_IDX:
*val = 44;
*val2 = 250000;
return IIO_VAL_INT_PLUS_MICRO;
case VZ89X_VOC_TVOC_IDX:
*val = -13;
return IIO_VAL_INT;
default:
return -EINVAL;
}
}
return ret;
}
static const struct iio_info vz89x_info = {
.attrs = &vz89x_attrs_group,
.read_raw = vz89x_read_raw,
.driver_module = THIS_MODULE,
};
static int vz89x_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct iio_dev *indio_dev;
struct vz89x_data *data;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA |
I2C_FUNC_SMBUS_BYTE))
return -ENODEV;
indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
data = iio_priv(indio_dev);
i2c_set_clientdata(client, indio_dev);
data->client = client;
data->last_update = jiffies - HZ;
mutex_init(&data->lock);
indio_dev->dev.parent = &client->dev;
indio_dev->info = &vz89x_info,
indio_dev->name = dev_name(&client->dev);
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = vz89x_channels;
indio_dev->num_channels = ARRAY_SIZE(vz89x_channels);
return devm_iio_device_register(&client->dev, indio_dev);
}
static const struct i2c_device_id vz89x_id[] = {
{ "vz89x", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, vz89x_id);
static const struct of_device_id vz89x_dt_ids[] = {
{ .compatible = "sgx,vz89x" },
{ }
};
MODULE_DEVICE_TABLE(of, vz89x_dt_ids);
static struct i2c_driver vz89x_driver = {
.driver = {
.name = "vz89x",
.of_match_table = of_match_ptr(vz89x_dt_ids),
},
.probe = vz89x_probe,
.id_table = vz89x_id,
};
module_i2c_driver(vz89x_driver);
MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
MODULE_DESCRIPTION("SGX Sensortech MiCS VZ89X VOC sensors");
MODULE_LICENSE("GPL v2");