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SubjectRe: [PATCH v4 1/2] iio: light: add driver for MAX44009
On Thu, 31 Jan 2019 07:29:01 -0800
Robert Eshleman <bobbyeshleman@gmail.com> wrote:

> The MAX44009 is a low-power ambient light sensor from Maxim
> Integrated. It differs from the MAX44000 in that it doesn't have
> proximity sensing and that it requires far less current (1 micro-amp
> vs 5 micro-amps). The register mapping and feature set between the
> two are different enough to require a new driver for the MAX44009.
>
> Developed and tested with a BeagleBone Black and UDOO Neo (i.MX6SX)
>
> Supported features:
>
> * Reading lux (processed value)
>
> * Rising and falling illuminance threshold
> events
>
> * Configuring integration time
>
> https://datasheets.maximintegrated.com/en/ds/MAX44009.pdf
>
> Signed-off-by: Robert Eshleman <bobbyeshleman@gmail.com>
Applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to play with it.

Thanks,

Jonathan

> ---
> Changes to v4:
> - Reformat subject line
> - Clean up whitespace
>
> Changes to v3:
> - Remove unnecessary mask when setting integration time
> - Return IRQ_NONE in IRQ handler when interrupt not from this device
> - Fix incorrect register usage when reading lux low byte
> - Clean up style
>
> Changes to v2:
> - Remove unnecessary mutex locking
> - Remove unnecessary triggered buffer support
> - Remove unnecessary wrapper functions for smbus reads and writes
> - Remove scale avail support
> - Use constant scale to provide processed values instead of raw
> - Remove IRQ_NONE return for non-shared IRQ
> - Clean up style
>
> drivers/iio/light/Kconfig | 10 +
> drivers/iio/light/Makefile | 1 +
> drivers/iio/light/max44009.c | 555 +++++++++++++++++++++++++++++++++++
> 3 files changed, 566 insertions(+)
> create mode 100644 drivers/iio/light/max44009.c
>
> diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
> index 36f458433480..5190eacfeb0a 100644
> --- a/drivers/iio/light/Kconfig
> +++ b/drivers/iio/light/Kconfig
> @@ -299,6 +299,16 @@ config MAX44000
> To compile this driver as a module, choose M here:
> the module will be called max44000.
>
> +config MAX44009
> + tristate "MAX44009 Ambient Light Sensor"
> + depends on I2C
> + help
> + Say Y here if you want to build support for Maxim Integrated's
> + MAX44009 ambient light sensor device.
> +
> + To compile this driver as a module, choose M here:
> + the module will be called max44009.
> +
> config OPT3001
> tristate "Texas Instruments OPT3001 Light Sensor"
> depends on I2C
> diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
> index 286bf3975372..e40794fbb435 100644
> --- a/drivers/iio/light/Makefile
> +++ b/drivers/iio/light/Makefile
> @@ -28,6 +28,7 @@ obj-$(CONFIG_SENSORS_LM3533) += lm3533-als.o
> obj-$(CONFIG_LTR501) += ltr501.o
> obj-$(CONFIG_LV0104CS) += lv0104cs.o
> obj-$(CONFIG_MAX44000) += max44000.o
> +obj-$(CONFIG_MAX44009) += max44009.o
> obj-$(CONFIG_OPT3001) += opt3001.o
> obj-$(CONFIG_PA12203001) += pa12203001.o
> obj-$(CONFIG_RPR0521) += rpr0521.o
> diff --git a/drivers/iio/light/max44009.c b/drivers/iio/light/max44009.c
> new file mode 100644
> index 000000000000..00ba15499638
> --- /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->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");

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