diff options
Diffstat (limited to 'drivers/iio/chemical/vz89x.c')
| -rw-r--r-- | drivers/iio/chemical/vz89x.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/drivers/iio/chemical/vz89x.c b/drivers/iio/chemical/vz89x.c new file mode 100644 index 000000000000..11e59a5a5112 --- /dev/null +++ b/drivers/iio/chemical/vz89x.c @@ -0,0 +1,256 @@ +/* + * 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"); |