diff options
Diffstat (limited to 'drivers/iio/light/max44009.c')
| -rw-r--r-- | drivers/iio/light/max44009.c | 555 |
1 files changed, 555 insertions, 0 deletions
diff --git a/drivers/iio/light/max44009.c b/drivers/iio/light/max44009.c new file mode 100644 index 000000000..f3648f20e --- /dev/null +++ b/drivers/iio/light/max44009.c @@ -0,0 +1,555 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * max44009.c - Support for MAX44009 Ambient Light Sensor + * + * Copyright (c) 2019 Robert Eshleman <bobbyeshleman@gmail.com> + * + * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX44009.pdf + * + * TODO: Support continuous mode and configuring from manual mode to + * automatic mode. + * + * Default I2C address: 0x4a + */ + +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/bits.h> +#include <linux/i2c.h> +#include <linux/iio/events.h> +#include <linux/iio/iio.h> +#include <linux/iio/sysfs.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/util_macros.h> + +#define MAX44009_DRV_NAME "max44009" + +/* Registers in datasheet order */ +#define MAX44009_REG_INT_STATUS 0x0 +#define MAX44009_REG_INT_EN 0x1 +#define MAX44009_REG_CFG 0x2 +#define MAX44009_REG_LUX_HI 0x3 +#define MAX44009_REG_LUX_LO 0x4 +#define MAX44009_REG_UPPER_THR 0x5 +#define MAX44009_REG_LOWER_THR 0x6 +#define MAX44009_REG_THR_TIMER 0x7 + +#define MAX44009_CFG_TIM_MASK GENMASK(2, 0) +#define MAX44009_CFG_MAN_MODE_MASK BIT(6) + +/* The maximum rising threshold for the max44009 */ +#define MAX44009_MAXIMUM_THRESHOLD 7520256 + +#define MAX44009_THRESH_EXP_MASK (0xf << 4) +#define MAX44009_THRESH_EXP_RSHIFT 4 +#define MAX44009_THRESH_MANT_LSHIFT 4 +#define MAX44009_THRESH_MANT_MASK 0xf + +#define MAX44009_UPPER_THR_MINIMUM 15 + +/* The max44009 always scales raw readings by 0.045 and is non-configurable */ +#define MAX44009_SCALE_NUMERATOR 45 +#define MAX44009_SCALE_DENOMINATOR 1000 + +/* The fixed-point fractional multiplier for de-scaling threshold values */ +#define MAX44009_FRACT_MULT 1000000 + +static const u32 max44009_int_time_ns_array[] = { + 800000000, + 400000000, + 200000000, + 100000000, + 50000000, /* Manual mode only */ + 25000000, /* Manual mode only */ + 12500000, /* Manual mode only */ + 6250000, /* Manual mode only */ +}; + +static const char max44009_int_time_str[] = + "0.8 " + "0.4 " + "0.2 " + "0.1 " + "0.05 " + "0.025 " + "0.0125 " + "0.00625"; + +struct max44009_data { + struct i2c_client *client; + struct mutex lock; +}; + +static const struct iio_event_spec max44009_event_spec[] = { + { + .type = IIO_EV_TYPE_THRESH, + .dir = IIO_EV_DIR_RISING, + .mask_separate = BIT(IIO_EV_INFO_VALUE) | + BIT(IIO_EV_INFO_ENABLE), + }, + { + .type = IIO_EV_TYPE_THRESH, + .dir = IIO_EV_DIR_FALLING, + .mask_separate = BIT(IIO_EV_INFO_VALUE) | + BIT(IIO_EV_INFO_ENABLE), + }, +}; + +static const struct iio_chan_spec max44009_channels[] = { + { + .type = IIO_LIGHT, + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) | + BIT(IIO_CHAN_INFO_INT_TIME), + .event_spec = max44009_event_spec, + .num_event_specs = ARRAY_SIZE(max44009_event_spec), + }, +}; + +static int max44009_read_int_time(struct max44009_data *data) +{ + + int ret = i2c_smbus_read_byte_data(data->client, MAX44009_REG_CFG); + + if (ret < 0) + return ret; + + return max44009_int_time_ns_array[ret & MAX44009_CFG_TIM_MASK]; +} + +static int max44009_write_int_time(struct max44009_data *data, + int val, int val2) +{ + struct i2c_client *client = data->client; + int ret, int_time, config; + s64 ns; + + ns = val * NSEC_PER_SEC + val2; + int_time = find_closest_descending( + ns, + max44009_int_time_ns_array, + ARRAY_SIZE(max44009_int_time_ns_array)); + + ret = i2c_smbus_read_byte_data(client, MAX44009_REG_CFG); + if (ret < 0) + return ret; + + config = ret; + config &= int_time; + + /* + * To set the integration time, the device must also be in manual + * mode. + */ + config |= MAX44009_CFG_MAN_MODE_MASK; + + return i2c_smbus_write_byte_data(client, MAX44009_REG_CFG, config); +} + +static int max44009_write_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, int val, + int val2, long mask) +{ + struct max44009_data *data = iio_priv(indio_dev); + int ret; + + if (mask == IIO_CHAN_INFO_INT_TIME && chan->type == IIO_LIGHT) { + mutex_lock(&data->lock); + ret = max44009_write_int_time(data, val, val2); + mutex_unlock(&data->lock); + return ret; + } + return -EINVAL; +} + +static int max44009_write_raw_get_fmt(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + long mask) +{ + return IIO_VAL_INT_PLUS_NANO; +} + +static int max44009_lux_raw(u8 hi, u8 lo) +{ + int mantissa; + int exponent; + + /* + * The mantissa consists of the low nibble of the Lux High Byte + * and the low nibble of the Lux Low Byte. + */ + mantissa = ((hi & 0xf) << 4) | (lo & 0xf); + + /* The exponent byte is just the upper nibble of the Lux High Byte */ + exponent = (hi >> 4) & 0xf; + + /* + * The exponent value is base 2 to the power of the raw exponent byte. + */ + exponent = 1 << exponent; + + return exponent * mantissa; +} + +#define MAX44009_READ_LUX_XFER_LEN (4) + +static int max44009_read_lux_raw(struct max44009_data *data) +{ + int ret; + u8 hireg = MAX44009_REG_LUX_HI; + u8 loreg = MAX44009_REG_LUX_LO; + u8 lo = 0; + u8 hi = 0; + + struct i2c_msg msgs[] = { + { + .addr = data->client->addr, + .flags = 0, + .len = sizeof(hireg), + .buf = &hireg, + }, + { + .addr = data->client->addr, + .flags = I2C_M_RD, + .len = sizeof(hi), + .buf = &hi, + }, + { + .addr = data->client->addr, + .flags = 0, + .len = sizeof(loreg), + .buf = &loreg, + }, + { + .addr = data->client->addr, + .flags = I2C_M_RD, + .len = sizeof(lo), + .buf = &lo, + } + }; + + /* + * Use i2c_transfer instead of smbus read because i2c_transfer + * does NOT use a stop bit between address write and data read. + * Using a stop bit causes disjoint upper/lower byte reads and + * reduces accuracy. + */ + ret = i2c_transfer(data->client->adapter, + msgs, MAX44009_READ_LUX_XFER_LEN); + + if (ret != MAX44009_READ_LUX_XFER_LEN) + return -EIO; + + return max44009_lux_raw(hi, lo); +} + +static int max44009_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, int *val, + int *val2, long mask) +{ + struct max44009_data *data = iio_priv(indio_dev); + int lux_raw; + int ret; + + switch (mask) { + case IIO_CHAN_INFO_PROCESSED: + switch (chan->type) { + case IIO_LIGHT: + ret = max44009_read_lux_raw(data); + if (ret < 0) + return ret; + lux_raw = ret; + + *val = lux_raw * MAX44009_SCALE_NUMERATOR; + *val2 = MAX44009_SCALE_DENOMINATOR; + return IIO_VAL_FRACTIONAL; + default: + return -EINVAL; + } + case IIO_CHAN_INFO_INT_TIME: + switch (chan->type) { + case IIO_LIGHT: + ret = max44009_read_int_time(data); + if (ret < 0) + return ret; + + *val2 = ret; + *val = 0; + return IIO_VAL_INT_PLUS_NANO; + default: + return -EINVAL; + } + default: + return -EINVAL; + } +} + +static IIO_CONST_ATTR(illuminance_integration_time_available, + max44009_int_time_str); + +static struct attribute *max44009_attributes[] = { + &iio_const_attr_illuminance_integration_time_available.dev_attr.attr, + NULL, +}; + +static const struct attribute_group max44009_attribute_group = { + .attrs = max44009_attributes, +}; + +static int max44009_threshold_byte_from_fraction(int integral, int fractional) +{ + int mantissa, exp; + + if ((integral <= 0 && fractional <= 0) || + integral > MAX44009_MAXIMUM_THRESHOLD || + (integral == MAX44009_MAXIMUM_THRESHOLD && fractional != 0)) + return -EINVAL; + + /* Reverse scaling of fixed-point integral */ + mantissa = integral * MAX44009_SCALE_DENOMINATOR; + mantissa /= MAX44009_SCALE_NUMERATOR; + + /* Reverse scaling of fixed-point fractional */ + mantissa += fractional / MAX44009_FRACT_MULT * + (MAX44009_SCALE_DENOMINATOR / MAX44009_SCALE_NUMERATOR); + + for (exp = 0; mantissa > 0xff; exp++) + mantissa >>= 1; + + mantissa >>= 4; + mantissa &= 0xf; + exp <<= 4; + + return exp | mantissa; +} + +static int max44009_get_thr_reg(enum iio_event_direction dir) +{ + switch (dir) { + case IIO_EV_DIR_RISING: + return MAX44009_REG_UPPER_THR; + case IIO_EV_DIR_FALLING: + return MAX44009_REG_LOWER_THR; + default: + return -EINVAL; + } +} + +static int max44009_write_event_value(struct iio_dev *indio_dev, + const struct iio_chan_spec *chan, + enum iio_event_type type, + enum iio_event_direction dir, + enum iio_event_info info, + int val, int val2) +{ + struct max44009_data *data = iio_priv(indio_dev); + int reg, threshold; + + if (info != IIO_EV_INFO_VALUE || chan->type != IIO_LIGHT) + return -EINVAL; + + threshold = max44009_threshold_byte_from_fraction(val, val2); + if (threshold < 0) + return threshold; + + reg = max44009_get_thr_reg(dir); + if (reg < 0) + return reg; + + return i2c_smbus_write_byte_data(data->client, reg, threshold); +} + +static int max44009_read_threshold(struct iio_dev *indio_dev, + enum iio_event_direction dir) +{ + struct max44009_data *data = iio_priv(indio_dev); + int byte, reg; + int mantissa, exponent; + + reg = max44009_get_thr_reg(dir); + if (reg < 0) + return reg; + + byte = i2c_smbus_read_byte_data(data->client, reg); + if (byte < 0) + return byte; + + mantissa = byte & MAX44009_THRESH_MANT_MASK; + mantissa <<= MAX44009_THRESH_MANT_LSHIFT; + + /* + * To get the upper threshold, always adds the minimum upper threshold + * value to the shifted byte value (see datasheet). + */ + if (dir == IIO_EV_DIR_RISING) + mantissa += MAX44009_UPPER_THR_MINIMUM; + + /* + * Exponent is base 2 to the power of the threshold exponent byte + * value + */ + exponent = byte & MAX44009_THRESH_EXP_MASK; + exponent >>= MAX44009_THRESH_EXP_RSHIFT; + + return (1 << exponent) * mantissa; +} + +static int max44009_read_event_value(struct iio_dev *indio_dev, + const struct iio_chan_spec *chan, + enum iio_event_type type, + enum iio_event_direction dir, + enum iio_event_info info, + int *val, int *val2) +{ + int ret; + int threshold; + + if (chan->type != IIO_LIGHT || type != IIO_EV_TYPE_THRESH) + return -EINVAL; + + ret = max44009_read_threshold(indio_dev, dir); + if (ret < 0) + return ret; + threshold = ret; + + *val = threshold * MAX44009_SCALE_NUMERATOR; + *val2 = MAX44009_SCALE_DENOMINATOR; + + return IIO_VAL_FRACTIONAL; +} + +static int max44009_write_event_config(struct iio_dev *indio_dev, + const struct iio_chan_spec *chan, + enum iio_event_type type, + enum iio_event_direction dir, + int state) +{ + struct max44009_data *data = iio_priv(indio_dev); + int ret; + + if (chan->type != IIO_LIGHT || type != IIO_EV_TYPE_THRESH) + return -EINVAL; + + ret = i2c_smbus_write_byte_data(data->client, + MAX44009_REG_INT_EN, state); + if (ret < 0) + return ret; + + /* + * Set device to trigger interrupt immediately upon exceeding + * the threshold limit. + */ + return i2c_smbus_write_byte_data(data->client, + MAX44009_REG_THR_TIMER, 0); +} + +static int max44009_read_event_config(struct iio_dev *indio_dev, + const struct iio_chan_spec *chan, + enum iio_event_type type, + enum iio_event_direction dir) +{ + struct max44009_data *data = iio_priv(indio_dev); + + if (chan->type != IIO_LIGHT || type != IIO_EV_TYPE_THRESH) + return -EINVAL; + + return i2c_smbus_read_byte_data(data->client, MAX44009_REG_INT_EN); +} + +static const struct iio_info max44009_info = { + .read_raw = max44009_read_raw, + .write_raw = max44009_write_raw, + .write_raw_get_fmt = max44009_write_raw_get_fmt, + .read_event_value = max44009_read_event_value, + .read_event_config = max44009_read_event_config, + .write_event_value = max44009_write_event_value, + .write_event_config = max44009_write_event_config, + .attrs = &max44009_attribute_group, +}; + +static irqreturn_t max44009_threaded_irq_handler(int irq, void *p) +{ + struct iio_dev *indio_dev = p; + struct max44009_data *data = iio_priv(indio_dev); + int ret; + + ret = i2c_smbus_read_byte_data(data->client, MAX44009_REG_INT_STATUS); + if (ret) { + iio_push_event(indio_dev, + IIO_UNMOD_EVENT_CODE(IIO_LIGHT, 0, + IIO_EV_TYPE_THRESH, + IIO_EV_DIR_EITHER), + iio_get_time_ns(indio_dev)); + + return IRQ_HANDLED; + } + + return IRQ_NONE; +} + +static int max44009_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct max44009_data *data; + struct iio_dev *indio_dev; + int ret; + + 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; + indio_dev->info = &max44009_info; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->name = MAX44009_DRV_NAME; + indio_dev->channels = max44009_channels; + indio_dev->num_channels = ARRAY_SIZE(max44009_channels); + mutex_init(&data->lock); + + /* Clear any stale interrupt bit */ + ret = i2c_smbus_read_byte_data(client, MAX44009_REG_CFG); + if (ret < 0) + return ret; + + if (client->irq > 0) { + ret = devm_request_threaded_irq(&client->dev, client->irq, + NULL, + max44009_threaded_irq_handler, + IRQF_TRIGGER_FALLING | + IRQF_ONESHOT | IRQF_SHARED, + "max44009_event", + indio_dev); + if (ret < 0) + return ret; + } + + return devm_iio_device_register(&client->dev, indio_dev); +} + +static const struct of_device_id max44009_of_match[] = { + { .compatible = "maxim,max44009" }, + { } +}; +MODULE_DEVICE_TABLE(of, max44009_of_match); + +static const struct i2c_device_id max44009_id[] = { + { "max44009", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, max44009_id); + +static struct i2c_driver max44009_driver = { + .driver = { + .name = MAX44009_DRV_NAME, + .of_match_table = max44009_of_match, + }, + .probe = max44009_probe, + .id_table = max44009_id, +}; +module_i2c_driver(max44009_driver); + +MODULE_AUTHOR("Robert Eshleman <bobbyeshleman@gmail.com>"); +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("MAX44009 ambient light sensor driver"); |