diff options
Diffstat (limited to 'drivers/iio/light/ltr390.c')
| -rw-r--r-- | drivers/iio/light/ltr390.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/drivers/iio/light/ltr390.c b/drivers/iio/light/ltr390.c new file mode 100644 index 0000000000..fff1e89909 --- /dev/null +++ b/drivers/iio/light/ltr390.c @@ -0,0 +1,196 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * IIO driver for Lite-On LTR390 ALS and UV sensor + * (7-bit I2C slave address 0x53) + * + * Based on the work of: + * Shreeya Patel and Shi Zhigang (LTRF216 Driver) + * + * Copyright (C) 2023 Anshul Dalal <anshulusr@gmail.com> + * + * Datasheet: + * https://optoelectronics.liteon.com/upload/download/DS86-2015-0004/LTR-390UV_Final_%20DS_V1%201.pdf + * + * TODO: + * - Support for configurable gain and resolution + * - Sensor suspend/resume support + * - Add support for reading the ALS + * - Interrupt support + */ + +#include <linux/i2c.h> +#include <linux/math.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/regmap.h> + +#include <linux/iio/iio.h> + +#include <asm/unaligned.h> + +#define LTR390_MAIN_CTRL 0x00 +#define LTR390_PART_ID 0x06 +#define LTR390_UVS_DATA 0x10 + +#define LTR390_SW_RESET BIT(4) +#define LTR390_UVS_MODE BIT(3) +#define LTR390_SENSOR_ENABLE BIT(1) + +#define LTR390_PART_NUMBER_ID 0xb + +/* + * At 20-bit resolution (integration time: 400ms) and 18x gain, 2300 counts of + * the sensor are equal to 1 UV Index [Datasheet Page#8]. + * + * For the default resolution of 18-bit (integration time: 100ms) and default + * gain of 3x, the counts/uvi are calculated as follows: + * 2300 / ((3/18) * (100/400)) = 95.83 + */ +#define LTR390_COUNTS_PER_UVI 96 + +/* + * Window Factor is needed when the device is under Window glass with coated + * tinted ink. This is to compensate for the light loss due to the lower + * transmission rate of the window glass and helps * in calculating lux. + */ +#define LTR390_WINDOW_FACTOR 1 + +struct ltr390_data { + struct regmap *regmap; + struct i2c_client *client; + /* Protects device from simulataneous reads */ + struct mutex lock; +}; + +static const struct regmap_config ltr390_regmap_config = { + .name = "ltr390", + .reg_bits = 8, + .reg_stride = 1, + .val_bits = 8, +}; + +static int ltr390_register_read(struct ltr390_data *data, u8 register_address) +{ + struct device *dev = &data->client->dev; + int ret; + u8 recieve_buffer[3]; + + guard(mutex)(&data->lock); + + ret = regmap_bulk_read(data->regmap, register_address, recieve_buffer, + sizeof(recieve_buffer)); + if (ret) { + dev_err(dev, "failed to read measurement data"); + return ret; + } + + return get_unaligned_le24(recieve_buffer); +} + +static int ltr390_read_raw(struct iio_dev *iio_device, + struct iio_chan_spec const *chan, int *val, + int *val2, long mask) +{ + int ret; + struct ltr390_data *data = iio_priv(iio_device); + + switch (mask) { + case IIO_CHAN_INFO_RAW: + ret = ltr390_register_read(data, LTR390_UVS_DATA); + if (ret < 0) + return ret; + *val = ret; + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: + *val = LTR390_WINDOW_FACTOR; + *val2 = LTR390_COUNTS_PER_UVI; + return IIO_VAL_FRACTIONAL; + default: + return -EINVAL; + } +} + +static const struct iio_info ltr390_info = { + .read_raw = ltr390_read_raw, +}; + +static const struct iio_chan_spec ltr390_channel = { + .type = IIO_UVINDEX, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) +}; + +static int ltr390_probe(struct i2c_client *client) +{ + struct ltr390_data *data; + struct iio_dev *indio_dev; + struct device *dev; + int ret, part_number; + + dev = &client->dev; + indio_dev = devm_iio_device_alloc(dev, sizeof(*data)); + if (!indio_dev) + return -ENOMEM; + + data = iio_priv(indio_dev); + + data->regmap = devm_regmap_init_i2c(client, <r390_regmap_config); + if (IS_ERR(data->regmap)) + return dev_err_probe(dev, PTR_ERR(data->regmap), + "regmap initialization failed\n"); + + data->client = client; + mutex_init(&data->lock); + + indio_dev->info = <r390_info; + indio_dev->channels = <r390_channel; + indio_dev->num_channels = 1; + indio_dev->name = "ltr390"; + + ret = regmap_read(data->regmap, LTR390_PART_ID, &part_number); + if (ret) + return dev_err_probe(dev, ret, + "failed to get sensor's part id\n"); + /* Lower 4 bits of `part_number` change with hardware revisions */ + if (part_number >> 4 != LTR390_PART_NUMBER_ID) + dev_info(dev, "received invalid product id: 0x%x", part_number); + dev_dbg(dev, "LTR390, product id: 0x%x\n", part_number); + + /* reset sensor, chip fails to respond to this, so ignore any errors */ + regmap_set_bits(data->regmap, LTR390_MAIN_CTRL, LTR390_SW_RESET); + + /* Wait for the registers to reset before proceeding */ + usleep_range(1000, 2000); + + ret = regmap_set_bits(data->regmap, LTR390_MAIN_CTRL, + LTR390_SENSOR_ENABLE | LTR390_UVS_MODE); + if (ret) + return dev_err_probe(dev, ret, "failed to enable the sensor\n"); + + return devm_iio_device_register(dev, indio_dev); +} + +static const struct i2c_device_id ltr390_id[] = { + { "ltr390" }, + { /* Sentinel */ } +}; +MODULE_DEVICE_TABLE(i2c, ltr390_id); + +static const struct of_device_id ltr390_of_table[] = { + { .compatible = "liteon,ltr390" }, + { /* Sentinel */ } +}; +MODULE_DEVICE_TABLE(of, ltr390_of_table); + +static struct i2c_driver ltr390_driver = { + .driver = { + .name = "ltr390", + .of_match_table = ltr390_of_table, + }, + .probe = ltr390_probe, + .id_table = ltr390_id, +}; +module_i2c_driver(ltr390_driver); + +MODULE_AUTHOR("Anshul Dalal <anshulusr@gmail.com>"); +MODULE_DESCRIPTION("Lite-On LTR390 ALS and UV sensor Driver"); +MODULE_LICENSE("GPL"); |