/* * ccs811.c - Support for AMS CCS811 VOC Sensor * * Copyright (C) 2017 Narcisa Vasile * * Datasheet: ams.com/content/download/951091/2269479/CCS811_DS000459_3-00.pdf * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * IIO driver for AMS CCS811 (I2C address 0x5A/0x5B set by ADDR Low/High) * * TODO: * 1. Make the drive mode selectable form userspace * 2. Add support for interrupts * 3. Adjust time to wait for data to be ready based on selected operation mode * 4. Read error register and put the information in logs */ #include #include #include #include #include #include #include #define CCS811_STATUS 0x00 #define CCS811_MEAS_MODE 0x01 #define CCS811_ALG_RESULT_DATA 0x02 #define CCS811_RAW_DATA 0x03 #define CCS811_HW_ID 0x20 #define CCS881_HW_ID_VALUE 0x81 #define CCS811_HW_VERSION 0x21 #define CCS811_HW_VERSION_VALUE 0x10 #define CCS811_HW_VERSION_MASK 0xF0 #define CCS811_ERR 0xE0 /* Used to transition from boot to application mode */ #define CCS811_APP_START 0xF4 /* Status register flags */ #define CCS811_STATUS_ERROR BIT(0) #define CCS811_STATUS_DATA_READY BIT(3) #define CCS811_STATUS_APP_VALID_MASK BIT(4) #define CCS811_STATUS_APP_VALID_LOADED BIT(4) /* * Value of FW_MODE bit of STATUS register describes the sensor's state: * 0: Firmware is in boot mode, this allows new firmware to be loaded * 1: Firmware is in application mode. CCS811 is ready to take ADC measurements */ #define CCS811_STATUS_FW_MODE_MASK BIT(7) #define CCS811_STATUS_FW_MODE_APPLICATION BIT(7) /* Measurement modes */ #define CCS811_MODE_IDLE 0x00 #define CCS811_MODE_IAQ_1SEC 0x10 #define CCS811_MODE_IAQ_10SEC 0x20 #define CCS811_MODE_IAQ_60SEC 0x30 #define CCS811_MODE_RAW_DATA 0x40 #define CCS811_VOLTAGE_MASK 0x3FF struct ccs811_reading { __be16 co2; __be16 voc; u8 status; u8 error; __be16 resistance; } __attribute__((__packed__)); struct ccs811_data { struct i2c_client *client; struct mutex lock; /* Protect readings */ struct ccs811_reading buffer; /* Ensures correct alignment of timestamp if present */ struct { s16 channels[2]; s64 ts __aligned(8); } scan; }; static const struct iio_chan_spec ccs811_channels[] = { { .type = IIO_CURRENT, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), .scan_index = -1, }, { .type = IIO_VOLTAGE, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), .scan_index = -1, }, { .type = IIO_CONCENTRATION, .channel2 = IIO_MOD_CO2, .modified = 1, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), .scan_index = 0, .scan_type = { .sign = 'u', .realbits = 16, .storagebits = 16, .endianness = IIO_BE, }, }, { .type = IIO_CONCENTRATION, .channel2 = IIO_MOD_VOC, .modified = 1, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), .scan_index = 1, .scan_type = { .sign = 'u', .realbits = 16, .storagebits = 16, .endianness = IIO_BE, }, }, IIO_CHAN_SOFT_TIMESTAMP(2), }; /* * The CCS811 powers-up in boot mode. A setup write to CCS811_APP_START will * transition the sensor to application mode. */ static int ccs811_start_sensor_application(struct i2c_client *client) { int ret; ret = i2c_smbus_read_byte_data(client, CCS811_STATUS); if (ret < 0) return ret; if ((ret & CCS811_STATUS_FW_MODE_APPLICATION)) return 0; if ((ret & CCS811_STATUS_APP_VALID_MASK) != CCS811_STATUS_APP_VALID_LOADED) return -EIO; ret = i2c_smbus_write_byte(client, CCS811_APP_START); if (ret < 0) return ret; ret = i2c_smbus_read_byte_data(client, CCS811_STATUS); if (ret < 0) return ret; if ((ret & CCS811_STATUS_FW_MODE_MASK) != CCS811_STATUS_FW_MODE_APPLICATION) { dev_err(&client->dev, "Application failed to start. Sensor is still in boot mode.\n"); return -EIO; } return 0; } static int ccs811_setup(struct i2c_client *client) { int ret; ret = ccs811_start_sensor_application(client); if (ret < 0) return ret; return i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE, CCS811_MODE_IAQ_1SEC); } static int ccs811_get_measurement(struct ccs811_data *data) { int ret, tries = 11; /* Maximum waiting time: 1s, as measurements are made every second */ while (tries-- > 0) { ret = i2c_smbus_read_byte_data(data->client, CCS811_STATUS); if (ret < 0) return ret; if ((ret & CCS811_STATUS_DATA_READY) || tries == 0) break; msleep(100); } if (!(ret & CCS811_STATUS_DATA_READY)) return -EIO; return i2c_smbus_read_i2c_block_data(data->client, CCS811_ALG_RESULT_DATA, 8, (char *)&data->buffer); } static int ccs811_read_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan, int *val, int *val2, long mask) { struct ccs811_data *data = iio_priv(indio_dev); int ret; switch (mask) { case IIO_CHAN_INFO_RAW: mutex_lock(&data->lock); ret = ccs811_get_measurement(data); if (ret < 0) { mutex_unlock(&data->lock); return ret; } switch (chan->type) { case IIO_VOLTAGE: *val = be16_to_cpu(data->buffer.resistance) & CCS811_VOLTAGE_MASK; ret = IIO_VAL_INT; break; case IIO_CURRENT: *val = be16_to_cpu(data->buffer.resistance) >> 10; ret = IIO_VAL_INT; break; case IIO_CONCENTRATION: switch (chan->channel2) { case IIO_MOD_CO2: *val = be16_to_cpu(data->buffer.co2); ret = IIO_VAL_INT; break; case IIO_MOD_VOC: *val = be16_to_cpu(data->buffer.voc); ret = IIO_VAL_INT; break; default: ret = -EINVAL; } break; default: ret = -EINVAL; } mutex_unlock(&data->lock); return ret; case IIO_CHAN_INFO_SCALE: switch (chan->type) { case IIO_VOLTAGE: *val = 1; *val2 = 612903; return IIO_VAL_INT_PLUS_MICRO; case IIO_CURRENT: *val = 0; *val2 = 1000; return IIO_VAL_INT_PLUS_MICRO; case IIO_CONCENTRATION: switch (chan->channel2) { case IIO_MOD_CO2: *val = 0; *val2 = 100; return IIO_VAL_INT_PLUS_MICRO; case IIO_MOD_VOC: *val = 0; *val2 = 100; return IIO_VAL_INT_PLUS_NANO; default: return -EINVAL; } default: return -EINVAL; } default: return -EINVAL; } } static const struct iio_info ccs811_info = { .read_raw = ccs811_read_raw, .driver_module = THIS_MODULE, }; static irqreturn_t ccs811_trigger_handler(int irq, void *p) { struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct ccs811_data *data = iio_priv(indio_dev); struct i2c_client *client = data->client; int ret; ret = i2c_smbus_read_i2c_block_data(client, CCS811_ALG_RESULT_DATA, sizeof(data->scan.channels), (u8 *)data->scan.channels); if (ret != 4) { dev_err(&client->dev, "cannot read sensor data\n"); goto err; } iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, iio_get_time_ns(indio_dev)); err: iio_trigger_notify_done(indio_dev->trig); return IRQ_HANDLED; } static int ccs811_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct iio_dev *indio_dev; struct ccs811_data *data; int ret; if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WRITE_BYTE | I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_READ_I2C_BLOCK)) return -EOPNOTSUPP; /* Check hardware id (should be 0x81 for this family of devices) */ ret = i2c_smbus_read_byte_data(client, CCS811_HW_ID); if (ret < 0) return ret; if (ret != CCS881_HW_ID_VALUE) { dev_err(&client->dev, "hardware id doesn't match CCS81x\n"); return -ENODEV; } ret = i2c_smbus_read_byte_data(client, CCS811_HW_VERSION); if (ret < 0) return ret; if ((ret & CCS811_HW_VERSION_MASK) != CCS811_HW_VERSION_VALUE) { dev_err(&client->dev, "no CCS811 sensor\n"); return -ENODEV; } indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); if (!indio_dev) return -ENOMEM; ret = ccs811_setup(client); if (ret < 0) return ret; data = iio_priv(indio_dev); i2c_set_clientdata(client, indio_dev); data->client = client; mutex_init(&data->lock); indio_dev->dev.parent = &client->dev; indio_dev->name = id->name; indio_dev->info = &ccs811_info; indio_dev->channels = ccs811_channels; indio_dev->num_channels = ARRAY_SIZE(ccs811_channels); ret = iio_triggered_buffer_setup(indio_dev, NULL, ccs811_trigger_handler, NULL); if (ret < 0) { dev_err(&client->dev, "triggered buffer setup failed\n"); goto err_poweroff; } ret = iio_device_register(indio_dev); if (ret < 0) { dev_err(&client->dev, "unable to register iio device\n"); goto err_buffer_cleanup; } return 0; err_buffer_cleanup: iio_triggered_buffer_cleanup(indio_dev); err_poweroff: i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE, CCS811_MODE_IDLE); return ret; } static int ccs811_remove(struct i2c_client *client) { struct iio_dev *indio_dev = i2c_get_clientdata(client); iio_device_unregister(indio_dev); iio_triggered_buffer_cleanup(indio_dev); return i2c_smbus_write_byte_data(client, CCS811_MEAS_MODE, CCS811_MODE_IDLE); } static const struct i2c_device_id ccs811_id[] = { {"ccs811", 0}, { } }; MODULE_DEVICE_TABLE(i2c, ccs811_id); static struct i2c_driver ccs811_driver = { .driver = { .name = "ccs811", }, .probe = ccs811_probe, .remove = ccs811_remove, .id_table = ccs811_id, }; module_i2c_driver(ccs811_driver); MODULE_AUTHOR("Narcisa Vasile "); MODULE_DESCRIPTION("CCS811 volatile organic compounds sensor"); MODULE_LICENSE("GPL v2");