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556 lines
13 KiB
C
556 lines
13 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* max44009.c - Support for MAX44009 Ambient Light Sensor
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*
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* Copyright (c) 2019 Robert Eshleman <bobbyeshleman@gmail.com>
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*
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* Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX44009.pdf
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*
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* TODO: Support continuous mode and configuring from manual mode to
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* automatic mode.
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*
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* Default I2C address: 0x4a
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*/
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/bits.h>
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#include <linux/i2c.h>
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#include <linux/iio/events.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/sysfs.h>
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#include <linux/interrupt.h>
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#include <linux/module.h>
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#include <linux/util_macros.h>
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#define MAX44009_DRV_NAME "max44009"
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/* Registers in datasheet order */
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#define MAX44009_REG_INT_STATUS 0x0
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#define MAX44009_REG_INT_EN 0x1
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#define MAX44009_REG_CFG 0x2
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#define MAX44009_REG_LUX_HI 0x3
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#define MAX44009_REG_LUX_LO 0x4
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#define MAX44009_REG_UPPER_THR 0x5
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#define MAX44009_REG_LOWER_THR 0x6
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#define MAX44009_REG_THR_TIMER 0x7
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#define MAX44009_CFG_TIM_MASK GENMASK(2, 0)
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#define MAX44009_CFG_MAN_MODE_MASK BIT(6)
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/* The maximum rising threshold for the max44009 */
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#define MAX44009_MAXIMUM_THRESHOLD 7520256
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#define MAX44009_THRESH_EXP_MASK (0xf << 4)
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#define MAX44009_THRESH_EXP_RSHIFT 4
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#define MAX44009_THRESH_MANT_LSHIFT 4
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#define MAX44009_THRESH_MANT_MASK 0xf
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#define MAX44009_UPPER_THR_MINIMUM 15
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/* The max44009 always scales raw readings by 0.045 and is non-configurable */
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#define MAX44009_SCALE_NUMERATOR 45
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#define MAX44009_SCALE_DENOMINATOR 1000
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/* The fixed-point fractional multiplier for de-scaling threshold values */
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#define MAX44009_FRACT_MULT 1000000
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static const u32 max44009_int_time_ns_array[] = {
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800000000,
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400000000,
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200000000,
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100000000,
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50000000, /* Manual mode only */
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25000000, /* Manual mode only */
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12500000, /* Manual mode only */
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6250000, /* Manual mode only */
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};
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static const char max44009_int_time_str[] =
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"0.8 "
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"0.4 "
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"0.2 "
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"0.1 "
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"0.05 "
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"0.025 "
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"0.0125 "
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"0.00625";
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struct max44009_data {
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struct i2c_client *client;
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struct mutex lock;
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};
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static const struct iio_event_spec max44009_event_spec[] = {
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{
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.type = IIO_EV_TYPE_THRESH,
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.dir = IIO_EV_DIR_RISING,
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.mask_separate = BIT(IIO_EV_INFO_VALUE) |
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BIT(IIO_EV_INFO_ENABLE),
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},
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{
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.type = IIO_EV_TYPE_THRESH,
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.dir = IIO_EV_DIR_FALLING,
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.mask_separate = BIT(IIO_EV_INFO_VALUE) |
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BIT(IIO_EV_INFO_ENABLE),
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},
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};
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static const struct iio_chan_spec max44009_channels[] = {
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{
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.type = IIO_LIGHT,
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.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
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BIT(IIO_CHAN_INFO_INT_TIME),
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.event_spec = max44009_event_spec,
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.num_event_specs = ARRAY_SIZE(max44009_event_spec),
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},
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};
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static int max44009_read_int_time(struct max44009_data *data)
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{
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int ret = i2c_smbus_read_byte_data(data->client, MAX44009_REG_CFG);
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if (ret < 0)
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return ret;
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return max44009_int_time_ns_array[ret & MAX44009_CFG_TIM_MASK];
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}
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static int max44009_write_int_time(struct max44009_data *data,
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int val, int val2)
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{
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struct i2c_client *client = data->client;
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int ret, int_time, config;
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s64 ns;
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ns = val * NSEC_PER_SEC + val2;
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int_time = find_closest_descending(
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ns,
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max44009_int_time_ns_array,
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ARRAY_SIZE(max44009_int_time_ns_array));
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ret = i2c_smbus_read_byte_data(client, MAX44009_REG_CFG);
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if (ret < 0)
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return ret;
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config = ret;
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config &= int_time;
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/*
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* To set the integration time, the device must also be in manual
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* mode.
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*/
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config |= MAX44009_CFG_MAN_MODE_MASK;
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return i2c_smbus_write_byte_data(client, MAX44009_REG_CFG, config);
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}
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static int max44009_write_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan, int val,
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int val2, long mask)
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{
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struct max44009_data *data = iio_priv(indio_dev);
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int ret;
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if (mask == IIO_CHAN_INFO_INT_TIME && chan->type == IIO_LIGHT) {
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mutex_lock(&data->lock);
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ret = max44009_write_int_time(data, val, val2);
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mutex_unlock(&data->lock);
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return ret;
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}
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return -EINVAL;
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}
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static int max44009_write_raw_get_fmt(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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long mask)
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{
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return IIO_VAL_INT_PLUS_NANO;
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}
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static int max44009_lux_raw(u8 hi, u8 lo)
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{
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int mantissa;
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int exponent;
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/*
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* The mantissa consists of the low nibble of the Lux High Byte
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* and the low nibble of the Lux Low Byte.
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*/
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mantissa = ((hi & 0xf) << 4) | (lo & 0xf);
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/* The exponent byte is just the upper nibble of the Lux High Byte */
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exponent = (hi >> 4) & 0xf;
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/*
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* The exponent value is base 2 to the power of the raw exponent byte.
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*/
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exponent = 1 << exponent;
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return exponent * mantissa;
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}
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#define MAX44009_READ_LUX_XFER_LEN (4)
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static int max44009_read_lux_raw(struct max44009_data *data)
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{
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int ret;
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u8 hireg = MAX44009_REG_LUX_HI;
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u8 loreg = MAX44009_REG_LUX_LO;
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u8 lo = 0;
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u8 hi = 0;
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struct i2c_msg msgs[] = {
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{
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.addr = data->client->addr,
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.flags = 0,
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.len = sizeof(hireg),
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.buf = &hireg,
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},
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{
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.addr = data->client->addr,
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.flags = I2C_M_RD,
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.len = sizeof(hi),
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.buf = &hi,
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},
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{
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.addr = data->client->addr,
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.flags = 0,
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.len = sizeof(loreg),
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.buf = &loreg,
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},
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{
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.addr = data->client->addr,
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.flags = I2C_M_RD,
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.len = sizeof(lo),
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.buf = &lo,
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}
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};
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/*
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* Use i2c_transfer instead of smbus read because i2c_transfer
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* does NOT use a stop bit between address write and data read.
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* Using a stop bit causes disjoint upper/lower byte reads and
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* reduces accuracy.
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*/
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ret = i2c_transfer(data->client->adapter,
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msgs, MAX44009_READ_LUX_XFER_LEN);
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if (ret != MAX44009_READ_LUX_XFER_LEN)
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return -EIO;
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return max44009_lux_raw(hi, lo);
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}
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static int max44009_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan, int *val,
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int *val2, long mask)
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{
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struct max44009_data *data = iio_priv(indio_dev);
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int lux_raw;
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int ret;
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switch (mask) {
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case IIO_CHAN_INFO_PROCESSED:
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switch (chan->type) {
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case IIO_LIGHT:
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ret = max44009_read_lux_raw(data);
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if (ret < 0)
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return ret;
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lux_raw = ret;
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*val = lux_raw * MAX44009_SCALE_NUMERATOR;
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*val2 = MAX44009_SCALE_DENOMINATOR;
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return IIO_VAL_FRACTIONAL;
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default:
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return -EINVAL;
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}
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case IIO_CHAN_INFO_INT_TIME:
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switch (chan->type) {
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case IIO_LIGHT:
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ret = max44009_read_int_time(data);
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if (ret < 0)
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return ret;
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*val2 = ret;
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*val = 0;
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return IIO_VAL_INT_PLUS_NANO;
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default:
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return -EINVAL;
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}
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default:
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return -EINVAL;
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}
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}
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static IIO_CONST_ATTR(illuminance_integration_time_available,
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max44009_int_time_str);
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static struct attribute *max44009_attributes[] = {
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&iio_const_attr_illuminance_integration_time_available.dev_attr.attr,
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NULL,
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};
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static const struct attribute_group max44009_attribute_group = {
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.attrs = max44009_attributes,
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};
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static int max44009_threshold_byte_from_fraction(int integral, int fractional)
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{
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int mantissa, exp;
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if ((integral <= 0 && fractional <= 0) ||
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integral > MAX44009_MAXIMUM_THRESHOLD ||
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(integral == MAX44009_MAXIMUM_THRESHOLD && fractional != 0))
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return -EINVAL;
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/* Reverse scaling of fixed-point integral */
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mantissa = integral * MAX44009_SCALE_DENOMINATOR;
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mantissa /= MAX44009_SCALE_NUMERATOR;
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/* Reverse scaling of fixed-point fractional */
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mantissa += fractional / MAX44009_FRACT_MULT *
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(MAX44009_SCALE_DENOMINATOR / MAX44009_SCALE_NUMERATOR);
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for (exp = 0; mantissa > 0xff; exp++)
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mantissa >>= 1;
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mantissa >>= 4;
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mantissa &= 0xf;
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exp <<= 4;
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return exp | mantissa;
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}
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static int max44009_get_thr_reg(enum iio_event_direction dir)
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{
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switch (dir) {
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case IIO_EV_DIR_RISING:
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return MAX44009_REG_UPPER_THR;
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case IIO_EV_DIR_FALLING:
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return MAX44009_REG_LOWER_THR;
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default:
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return -EINVAL;
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}
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}
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static int max44009_write_event_value(struct iio_dev *indio_dev,
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const struct iio_chan_spec *chan,
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enum iio_event_type type,
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enum iio_event_direction dir,
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enum iio_event_info info,
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int val, int val2)
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{
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struct max44009_data *data = iio_priv(indio_dev);
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int reg, threshold;
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if (info != IIO_EV_INFO_VALUE || chan->type != IIO_LIGHT)
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return -EINVAL;
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threshold = max44009_threshold_byte_from_fraction(val, val2);
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if (threshold < 0)
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return threshold;
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reg = max44009_get_thr_reg(dir);
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if (reg < 0)
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return reg;
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return i2c_smbus_write_byte_data(data->client, reg, threshold);
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}
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static int max44009_read_threshold(struct iio_dev *indio_dev,
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enum iio_event_direction dir)
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{
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struct max44009_data *data = iio_priv(indio_dev);
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int byte, reg;
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int mantissa, exponent;
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reg = max44009_get_thr_reg(dir);
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if (reg < 0)
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return reg;
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byte = i2c_smbus_read_byte_data(data->client, reg);
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if (byte < 0)
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return byte;
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mantissa = byte & MAX44009_THRESH_MANT_MASK;
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mantissa <<= MAX44009_THRESH_MANT_LSHIFT;
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/*
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* To get the upper threshold, always adds the minimum upper threshold
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* value to the shifted byte value (see datasheet).
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*/
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if (dir == IIO_EV_DIR_RISING)
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mantissa += MAX44009_UPPER_THR_MINIMUM;
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/*
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* Exponent is base 2 to the power of the threshold exponent byte
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* value
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*/
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exponent = byte & MAX44009_THRESH_EXP_MASK;
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exponent >>= MAX44009_THRESH_EXP_RSHIFT;
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return (1 << exponent) * mantissa;
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}
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static int max44009_read_event_value(struct iio_dev *indio_dev,
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const struct iio_chan_spec *chan,
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enum iio_event_type type,
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enum iio_event_direction dir,
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enum iio_event_info info,
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int *val, int *val2)
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{
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int ret;
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int threshold;
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if (chan->type != IIO_LIGHT || type != IIO_EV_TYPE_THRESH)
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return -EINVAL;
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ret = max44009_read_threshold(indio_dev, dir);
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if (ret < 0)
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return ret;
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threshold = ret;
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*val = threshold * MAX44009_SCALE_NUMERATOR;
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*val2 = MAX44009_SCALE_DENOMINATOR;
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return IIO_VAL_FRACTIONAL;
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}
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static int max44009_write_event_config(struct iio_dev *indio_dev,
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const struct iio_chan_spec *chan,
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enum iio_event_type type,
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enum iio_event_direction dir,
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int state)
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{
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struct max44009_data *data = iio_priv(indio_dev);
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int ret;
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if (chan->type != IIO_LIGHT || type != IIO_EV_TYPE_THRESH)
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return -EINVAL;
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ret = i2c_smbus_write_byte_data(data->client,
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MAX44009_REG_INT_EN, state);
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if (ret < 0)
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return ret;
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/*
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* Set device to trigger interrupt immediately upon exceeding
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* the threshold limit.
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*/
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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");
|