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554 lines
13 KiB
554 lines
13 KiB
// 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 <[email protected]> |
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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, |
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MAX44009_REG_THR_TIMER, 0); |
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} |
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static int max44009_read_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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{ |
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struct max44009_data *data = iio_priv(indio_dev); |
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if (chan->type != IIO_LIGHT || type != IIO_EV_TYPE_THRESH) |
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return -EINVAL; |
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return i2c_smbus_read_byte_data(data->client, MAX44009_REG_INT_EN); |
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} |
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static const struct iio_info max44009_info = { |
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.read_raw = max44009_read_raw, |
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.write_raw = max44009_write_raw, |
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.write_raw_get_fmt = max44009_write_raw_get_fmt, |
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.read_event_value = max44009_read_event_value, |
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.read_event_config = max44009_read_event_config, |
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.write_event_value = max44009_write_event_value, |
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.write_event_config = max44009_write_event_config, |
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.attrs = &max44009_attribute_group, |
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}; |
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static irqreturn_t max44009_threaded_irq_handler(int irq, void *p) |
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{ |
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struct iio_dev *indio_dev = p; |
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struct max44009_data *data = iio_priv(indio_dev); |
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int ret; |
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ret = i2c_smbus_read_byte_data(data->client, MAX44009_REG_INT_STATUS); |
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if (ret) { |
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iio_push_event(indio_dev, |
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IIO_UNMOD_EVENT_CODE(IIO_LIGHT, 0, |
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IIO_EV_TYPE_THRESH, |
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IIO_EV_DIR_EITHER), |
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iio_get_time_ns(indio_dev)); |
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return IRQ_HANDLED; |
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} |
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return IRQ_NONE; |
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} |
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static int max44009_probe(struct i2c_client *client, |
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const struct i2c_device_id *id) |
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{ |
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struct max44009_data *data; |
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struct iio_dev *indio_dev; |
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int ret; |
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indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); |
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if (!indio_dev) |
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return -ENOMEM; |
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data = iio_priv(indio_dev); |
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i2c_set_clientdata(client, indio_dev); |
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data->client = client; |
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indio_dev->info = &max44009_info; |
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indio_dev->modes = INDIO_DIRECT_MODE; |
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indio_dev->name = MAX44009_DRV_NAME; |
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indio_dev->channels = max44009_channels; |
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indio_dev->num_channels = ARRAY_SIZE(max44009_channels); |
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mutex_init(&data->lock); |
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/* Clear any stale interrupt bit */ |
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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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if (client->irq > 0) { |
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ret = devm_request_threaded_irq(&client->dev, client->irq, |
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NULL, |
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max44009_threaded_irq_handler, |
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IRQF_TRIGGER_FALLING | |
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IRQF_ONESHOT | IRQF_SHARED, |
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"max44009_event", |
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indio_dev); |
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if (ret < 0) |
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return ret; |
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} |
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return devm_iio_device_register(&client->dev, indio_dev); |
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} |
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static const struct i2c_device_id max44009_id[] = { |
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{ "max44009", 0 }, |
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{ } |
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}; |
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MODULE_DEVICE_TABLE(i2c, max44009_id); |
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static struct i2c_driver max44009_driver = { |
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.driver = { |
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.name = MAX44009_DRV_NAME, |
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}, |
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.probe = max44009_probe, |
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.id_table = max44009_id, |
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}; |
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module_i2c_driver(max44009_driver); |
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static const struct of_device_id max44009_of_match[] = { |
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{ .compatible = "maxim,max44009" }, |
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{ } |
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}; |
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MODULE_DEVICE_TABLE(of, max44009_of_match); |
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MODULE_AUTHOR("Robert Eshleman <[email protected]>"); |
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MODULE_LICENSE("GPL v2"); |
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MODULE_DESCRIPTION("MAX44009 ambient light sensor driver");
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