// 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->dev.parent = &client->dev;
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 i2c_device_id max44009_id[] = {
{ "max44009", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, max44009_id);
static struct i2c_driver max44009_driver = {
.driver = {
.name = MAX44009_DRV_NAME,
},
.probe = max44009_probe,
.id_table = max44009_id,
};
module_i2c_driver(max44009_driver);
static const struct of_device_id max44009_of_match[] = {
{ .compatible = "maxim,max44009" },
{ }
};
MODULE_DEVICE_TABLE(of, max44009_of_match);
MODULE_AUTHOR("Robert Eshleman <bobbyeshleman@gmail.com>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("MAX44009 ambient light sensor driver");
