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SubjectRe: [PATCH 1/3] iio: light: Add driver for ap3216c
On Mon, 11 Feb 2019 14:09:12 -0500
Sven Van Asbroeck <thesven73@gmail.com> wrote:

> Hi Robert,
>
> On Sun, Feb 10, 2019 at 3:39 PM Robert Eshleman <bobbyeshleman@gmail.com> wrote:
> >
> > This patch adds support for the ap3216c ambient light and proximity
> > sensor.
>
> Comments below.
>
Follow up inline...

Mostly looks good to me, but a few places to tidy up.

Thanks,

Jonathan

> >
> > Supported features include:
> >
> > * Illuminance (lux)
> > * Proximity (raw)
> > * IR (raw)
> > * Rising/falling threshold events for illuminance and proximity
> > * Calibration scale for illuminance
> > * Calibration bias for proximity
> >
> > Signed-off-by: Robert Eshleman <bobbyeshleman@gmail.com>
> > ---
> > drivers/iio/light/Kconfig | 11 +
> > drivers/iio/light/Makefile | 1 +
> > drivers/iio/light/ap3216c.c | 793 ++++++++++++++++++++++++++++++++++++
> > 3 files changed, 805 insertions(+)
> > create mode 100644 drivers/iio/light/ap3216c.c
> >
> > diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
> > index 36f458433480..74688d19beb1 100644
> > --- a/drivers/iio/light/Kconfig
> > +++ b/drivers/iio/light/Kconfig
> > @@ -41,6 +41,17 @@ config AL3320A
> > To compile this driver as a module, choose M here: the
> > module will be called al3320a.
> >
> > +config AP3216C
> > + tristate "AP3216C Ambient Light and Proximity sensor"
> > + select REGMAP_I2C
> > + depends on I2C
> > + help
> > + Say Y here to build a driver for the AP3216C Ambient Light and
> > + Proximity sensor.
> > +
> > + To compile this driver as a module, choose M here: the
> > + module will be called ap3216c.
> > +
> > config APDS9300
> > tristate "APDS9300 ambient light sensor"
> > depends on I2C
> > diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
> > index 286bf3975372..7d2f8fa0f30d 100644
> > --- a/drivers/iio/light/Makefile
> > +++ b/drivers/iio/light/Makefile
> > @@ -7,6 +7,7 @@
> > obj-$(CONFIG_ACPI_ALS) += acpi-als.o
> > obj-$(CONFIG_ADJD_S311) += adjd_s311.o
> > obj-$(CONFIG_AL3320A) += al3320a.o
> > +obj-$(CONFIG_AP3216C) += ap3216c.o
> > obj-$(CONFIG_APDS9300) += apds9300.o
> > obj-$(CONFIG_APDS9960) += apds9960.o
> > obj-$(CONFIG_BH1750) += bh1750.o
> > diff --git a/drivers/iio/light/ap3216c.c b/drivers/iio/light/ap3216c.c
> > new file mode 100644
> > index 000000000000..12802b45c01c
> > --- /dev/null
> > +++ b/drivers/iio/light/ap3216c.c
> > @@ -0,0 +1,793 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * AP3216C Ambient Light and Infrared Proximity Sensor
> > + *
> > + * Copyright (c) 2019, Robert Eshleman.
> > + *
> > + * Datasheet: https://pdf-datasheet-datasheet.netdna-ssl.com/pdf-down/A/P/3/AP3216C-LITE-ON.pdf
> > + *
> > + * 7-bit I2C slave address 0x1E
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/init.h>
> > +#include <linux/i2c.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/bits.h>
> > +#include <linux/regmap.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/iio/sysfs.h>
> > +#include <linux/iio/events.h>
> > +
> > +#define AP3216C_DRV_NAME "ap3216c"
> > +
> > +/* register addresses */
> > +#define AP3216C_SYS 0x0
> > +#define AP3216C_INT_STATUS 0x01
> > +#define AP3216C_INT_CLR 0x02
> > +#define AP3216C_IR_DATA_LO 0x0A
> > +#define AP3216C_IR_DATA_HI 0x0B
> > +#define AP3216C_ALS_DATA_LO 0x0C
> > +#define AP3216C_ALS_DATA_HI 0x0D
> > +#define AP3216C_PS_DATA_LO 0x0E
> > +#define AP3216C_PS_DATA_HI 0x0F
> > +#define AP3216C_ALS_CFG 0x10
> > +#define AP3216C_ALS_CALIB 0x19
> > +#define AP3216C_ALS_LO_THR_LO 0x1A
> > +#define AP3216C_ALS_LO_THR_HI 0x1B
> > +#define AP3216C_ALS_HI_THR_LO 0x1C
> > +#define AP3216C_ALS_HI_THR_HI 0x1D
> > +#define AP3216C_PS_CFG 0x20
> > +#define AP3216C_PS_CALIB_LO 0x28
> > +#define AP3216C_PS_CALIB_HI 0x29
> > +#define AP3216C_PS_LO_THR_LO 0x2A
> > +#define AP3216C_PS_LO_THR_HI 0x2B
> > +#define AP3216C_PS_HI_THR_LO 0x2C
> > +#define AP3216C_PS_HI_THR_HI 0x2D
> > +
> > +/* SYS_MODE mask and config value */
> > +#define AP3216C_SYS_MODE_ALS_PS GENMASK(1, 0)
> > +#define AP3216C_SYS_MODE_ALS_ONLY 0x01
> > +
> > +/* INT_STATUS masks and config value */
> > +#define AP3216C_INT_STATUS_ALS_MASK 1
> > +#define AP3216C_INT_STATUS_PS_MASK (1 << 1)
> > +#define AP3216C_INT_STATUS_CLR GENMASK(1, 0)
> > +#define AP3216C_INT_CLR_MANUAL 1
> > +
> > +/* IR_DATA mask/shift */
> > +#define AP3216C_IR_DATA_LO_MASK GENMASK(1, 0)
> > +#define AP3216C_IR_DATA_HI_SHIFT 2
> > +
> > +/* ALS_DATA shift and fractional helper */
> > +#define AP3216C_ALS_DATA_HI_SHIFT 8
> > +#define AP3216C_ALS_DATA_DENOM 100000
> > +
> > +/* ALS_CALIB masks/shifts */
> > +#define AP3216C_ALS_CALIB_INT_MASK GENMASK(7, 6)
> > +#define AP3216C_ALS_CALIB_INT_SHIFT 6
> > +#define AP3216C_ALS_CALIB_DEC_MASK GENMASK(5, 0)
> > +
> > +/* PS_DATA shifts/masks/bits */
> > +#define AP3216C_PS_DATA_LO_MASK GENMASK(3, 0)
> > +#define AP3216C_PS_DATA_LO_IR_OF BIT(6)
> > +#define AP3216C_PS_DATA_HI_MASK GENMASK(5, 0)
> > +#define AP3216C_PS_DATA_HI_SHIFT 4
> > +#define AP3216C_PS_DATA_HI_IR_OF BIT(6)
> > +
> > +/* ALS_CFG masks */
> > +#define AP3216C_ALS_CFG_GAIN_MASK GENMASK(5, 4)
> > +
> > +/* ALS_CALIB shifts */
> > +#define AP3216C_ALS_CALIB_INT_SHIFT 6
> > +
> > +/* ALS_HI_THR masks and shifts */
> > +#define AP3216C_ALS_HI_THR_LO_MASK GENMASK(7, 0)
> > +#define AP3216C_ALS_HI_THR_HI_SHIFT 8
> > +#define AP3216C_ALS_HI_THR_HI_MASK GENMASK(7, 4)
> > +#define AP3216C_ALS_HI_THR_HI_SHIFT 8
> > +
> > +/* ALS_LO_THR masks and shifts */
> > +#define AP3216C_ALS_LO_THR_LO_MASK GENMASK(3, 0)
> > +#define AP3216C_ALS_LO_THR_HI_MASK GENMASK(7, 4)
> > +#define AP3216C_ALS_LO_THR_HI_SHIFT 8
> > +
> > +/* PS_CFG reg mask/shift/bit values */
> > +#define AP3216C_PS_CFG_GAIN_MASK GENMASK(3, 2)
> > +#define AP3216C_PS_CFG_GAIN_SHIFT 2
> > +#define AP3216C_PS_CFG_GAIN(val) \
> > + (1 << ((val & AP3216C_PS_CFG_GAIN_MASK) >> AP3216C_PS_CFG_GAIN_SHIFT))
> > +
> > +/* PS_LO and PS_HI shift/mask and multiplier values */
> > +#define AP3216C_PS_LO_THR_HI_MULT 4
> > +#define AP3216C_PS_HI_THR_HI_SHIFT 2
> > +#define AP3216C_PS_HI_THR_HI_MULT 4
> > +
> > +/* PS_THR_LO and PS_THR_HI masks */
> > +#define AP3216C_PS_THR_LO_MASK GENMASK(1, 0)
> > +#define AP3216C_PS_THR_HI_MASK GENMASK(10, 2)
> > +
> > +/* PS_CALIB_HI and PS_CALIB_LO shift/mask/bit values */
> > +#define AP3216C_PS_CALIB_HI_SHIFT 1
> > +#define AP3216C_PS_CALIB_HI_MASK GENMASK(8, 1)
> > +#define AP3216C_PS_CALIB_LO_MASK BIT(0)
> > +
> > +/* ALS fractional helper values */
> > +#define AP3216C_ALS_INTEG_MULT 10000
> > +#define AP3216C_ALS_FRACT_DIV 100
> > +
> > +/* ALS_CALIB min/max values (0.0 <= ALS_CALIB <= 3.984375) */
> > +#define AP3216C_ALS_CALIB_INT_MIN 0
> > +#define AP3216C_ALS_CALIB_DEC_MIN 0
> > +#define AP3216C_ALS_CALIB_INT_MAX 3
> > +#define AP3216C_ALS_CALIB_DEC_MAX 984375
> > +
> > +/* ALS_CALIB conversion denominator */
> > +#define AP3216C_ALS_CALIB_DENOM 64
> > +
> > +#define AP3216C_IIO_MULT 1000000
> > +
> > +static u16 ap3216c_gain_array[] = {
> > + 3500, /* 0.3500 lux resolution */
> > + 788, /* 0.0788 lux resolution */
> > + 197, /* 0.0197 lux resolution */
> > + 49, /* 0.0049 lux resolution */
> > +};
> > +
> > +struct ap3216c_data {
> > + struct regmap *regmap;
> > + struct i2c_client *client;
> > + bool als_thresh_en;
> > + bool prox_thresh_en;
> > +};
> > +
> > +static const struct iio_event_spec ap3216c_event_spec[] = {
> > + {
> > + .type = IIO_EV_TYPE_THRESH,
> > + .dir = IIO_EV_DIR_RISING,
> > + .mask_separate = BIT(IIO_EV_INFO_VALUE),
> > + },
> > + {
> > + .type = IIO_EV_TYPE_THRESH,
> > + .dir = IIO_EV_DIR_FALLING,
> > + .mask_separate = BIT(IIO_EV_INFO_VALUE),
> > + },
> > + {
> > + .type = IIO_EV_TYPE_THRESH,
> > + .dir = IIO_EV_DIR_EITHER,
> > + .mask_shared_by_type = BIT(IIO_EV_INFO_ENABLE),
> > + },
> > +};
> > +
> > +static const struct iio_chan_spec ap3216c_channels[] = {
> > + {
> > + .type = IIO_LIGHT,
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> > + BIT(IIO_CHAN_INFO_CALIBSCALE),
> > + .event_spec = ap3216c_event_spec,
> > + .num_event_specs = ARRAY_SIZE(ap3216c_event_spec),
> > + },
> > + {
> > + .type = IIO_PROXIMITY,
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > + BIT(IIO_CHAN_INFO_CALIBBIAS),
> > + .event_spec = ap3216c_event_spec,
> > + .num_event_specs = ARRAY_SIZE(ap3216c_event_spec),
> > + },
> > + {
> > + .type = IIO_LIGHT,
> > + .modified = 1,
> > + .channel2 = IIO_MOD_LIGHT_IR,
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> > + }
> > +};
> > +
> > +static int ap3216c_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 ap3216c_data *data = iio_priv(indio_dev);
> > + int cfg, gain;
> > + int integral, fractional;
> > + int lo, hi;
> > + u16 thr;
> > + int ret;
> > +
> > + switch (chan->type) {
> > + case IIO_LIGHT:
> > + ret = regmap_read(data->regmap, AP3216C_ALS_CFG, &cfg);
> > + if (ret < 0)
> > + return ret;
> > +
> > + gain = ap3216c_gain_array[cfg & AP3216C_ALS_CFG_GAIN_MASK];
> > + integral = val * AP3216C_ALS_INTEG_MULT / gain;
> > + fractional = val2 / AP3216C_ALS_FRACT_DIV / gain;
> > +
> > + thr = integral + fractional;
> > +
> > + switch (dir) {
> > + case IIO_EV_DIR_RISING:
> > + ret = regmap_write(data->regmap, AP3216C_ALS_HI_THR_LO,
> > + thr & AP3216C_ALS_HI_THR_LO_MASK);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = regmap_write(data->regmap,
> > + AP3216C_ALS_HI_THR_HI,
> > + (thr & AP3216C_ALS_HI_THR_HI_MASK) >>
> > + AP3216C_ALS_HI_THR_HI_SHIFT);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return ret;
> > +
> > + case IIO_EV_DIR_FALLING:
> > + ret = regmap_write(data->regmap,
> > + AP3216C_ALS_LO_THR_LO,
> > + thr & AP3216C_ALS_LO_THR_LO_MASK);
> > +
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = regmap_write(data->regmap,
> > + AP3216C_ALS_LO_THR_HI,
> > + (thr & AP3216C_ALS_LO_THR_HI_MASK) >>
> > + AP3216C_ALS_LO_THR_HI_SHIFT);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return ret;
> > +
> > + default:
> > + return -EINVAL;
> > + }
> > + return -EINVAL;
> > +
> > + case IIO_PROXIMITY:
> > + lo = val & AP3216C_PS_THR_LO_MASK;
> > + hi = (val & AP3216C_PS_THR_HI_MASK) >>
> > + AP3216C_PS_HI_THR_HI_SHIFT;
> > +
> > + switch (dir) {
> > + case IIO_EV_DIR_RISING:
> > + ret = regmap_write(data->regmap,
> > + AP3216C_PS_HI_THR_LO, lo);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return regmap_write(data->regmap,
> > + AP3216C_PS_HI_THR_HI, hi);
> > +
> > + case IIO_EV_DIR_FALLING:
> > + ret = regmap_write(data->regmap,
> > + AP3216C_PS_LO_THR_LO, lo);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return regmap_write(data->regmap,
> > + AP3216C_PS_LO_THR_HI, hi);
> > +
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + default:
> > + return -EINVAL;
> > + }
> > + return -EINVAL;
> > +}
> > +
> > +static int ap3216c_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)
> > +{
> > + struct ap3216c_data *data = iio_priv(indio_dev);
> > + unsigned int lo, hi;
> > + int ret;
> > +
> > + switch (chan->type) {
> > + case IIO_LIGHT:
> > + switch (dir) {
> > + case IIO_EV_DIR_RISING:
> > + ret = regmap_read(data->regmap,
> > + AP3216C_ALS_HI_THR_LO, &lo);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = regmap_read(data->regmap,
> > + AP3216C_ALS_HI_THR_HI, &hi);
> > + if (ret < 0)
> > + return ret;
> > +
> > + *val = (hi << AP3216C_ALS_HI_THR_HI_SHIFT) | lo;
> > + return IIO_VAL_INT;
> > +
> > + case IIO_EV_DIR_FALLING:
> > + ret = regmap_read(data->regmap,
> > + AP3216C_ALS_LO_THR_LO, &lo);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = regmap_read(data->regmap,
> > + AP3216C_ALS_LO_THR_HI, &hi);
> > + if (ret < 0)
> > + return ret;
> > +
> > + *val = (hi << AP3216C_ALS_LO_THR_HI_SHIFT) | lo;
> > + return IIO_VAL_INT;
> > +
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + case IIO_PROXIMITY:
> > + switch (dir) {
> > + case IIO_EV_DIR_RISING:
> > + ret = regmap_read(data->regmap,
> > + AP3216C_PS_HI_THR_LO, &lo);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = regmap_read(data->regmap,
> > + AP3216C_PS_HI_THR_HI, &hi);
> > + if (ret < 0)
> > + return ret;
> > +
> > + *val = (hi * AP3216C_PS_HI_THR_HI_MULT) +
> > + (lo & AP3216C_PS_THR_LO_MASK);
> > +
> > + return IIO_VAL_INT;
> > +
> > + case IIO_EV_DIR_FALLING:
> > + ret = regmap_read(data->regmap,
> > + AP3216C_PS_LO_THR_LO, &lo);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = regmap_read(data->regmap,
> > + AP3216C_PS_LO_THR_HI, &hi);
>
> Does the iio core serialize access to this function?

It doesn't.

> If so, disregard this comment.
>
> If this function can be executed concurrently by multiple threads,
> then the read to _LO and _HI needs to be serialized. Otherwise
> you could end up reading nonsense values.
>
> Datasheet says that when _LO is read, _HI is latched into a
> temporary register. So imagine two threads reading out the value
> concurrently:
>
> Chip performs a conversion (call it 1)
> Thread A reads _LO (1), chip stores _HI(1), thread pauses
> The chip performs a new conversion (call it 2)
> Thread B reads _LO (2), chip stores _HI(2)
> Thread A wakes, reads _HI (2)
>
> So now thread A has a _LO from conversion (1), and a _HI from
> conversion (2) !!
>
> I think you could solve this by placing a mutex around the two
> reads, but see my comment below.

Agreed. Or potentially just use regmap_bulk_read and rely on
the regmap internal locking to do it for you.

>
> > + if (ret < 0)
> > + return ret;
> > +
> > + *val = (hi * AP3216C_PS_LO_THR_HI_MULT) +
> > + (lo & AP3216C_PS_THR_LO_MASK);
> > +
> > + return IIO_VAL_INT;
> > +
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + return -EINVAL;
> > +}
> > +
> > +static int ap3216c_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 ap3216c_data *data = iio_priv(indio_dev);
> > +
> > + switch (chan->type) {
> > + case IIO_LIGHT:
> > + return data->als_thresh_en;
> > +
> > + case IIO_PROXIMITY:
> > + return data->prox_thresh_en;
> > +
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + return -EINVAL;
> > +}
> > +
> > +static int ap3216c_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 ap3216c_data *data = iio_priv(indio_dev);
> > +
> > + switch (chan->type) {
> > + case IIO_LIGHT:
> > + data->als_thresh_en = state;
> > + return 0;
> > +
> > + case IIO_PROXIMITY:
> > + data->prox_thresh_en = state;
> > + return 0;
> > +
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + return -EINVAL;
> > +}
> > +
> > +static const struct regmap_config ap3216c_regmap_config = {
> > + .reg_bits = 8,
> > + .val_bits = 8,
> > + .max_register = AP3216C_PS_HI_THR_HI,
> > +};
> > +
> > +/**
> > + * Returns integral part of decimal between 0.0 and 3.984275
> > + */
> > +static int ap3216c_als_calibscale_int(int val)
> > +{
> > + if (val > AP3216C_ALS_CALIB_INT_MAX)
> > + return AP3216C_ALS_CALIB_INT_MAX;
> > +
> > + if (val <= AP3216C_ALS_CALIB_INT_MIN)
> > + return AP3216C_ALS_CALIB_INT_MIN;
> > +
> > + return val;
> > +}
> > +
> > +/**
> > + * Returns decimal part of decimal number between 0.0 and 3.984275
> > + */
> > +static int ap3216c_als_calibscale_dec(int val, int val2)
> > +{
> > + /* Return max decimal if number exceeds calibscale max */
> > + if (val > AP3216C_ALS_CALIB_INT_MAX ||
> > + (val == AP3216C_ALS_CALIB_INT_MAX &&
> > + val2 > AP3216C_ALS_CALIB_DEC_MAX))
> > + return AP3216C_ALS_CALIB_DEC_MAX;
> > +
> > + /* Floor the decimal if integral below minimum */
> > + if (val <= AP3216C_ALS_CALIB_INT_MIN)
> > + return AP3216C_ALS_CALIB_DEC_MIN;
> > +
> > + /* Floor the decimal if decimal below minimum */
> > + if (val2 < AP3216C_ALS_CALIB_DEC_MIN)
> > + return AP3216C_ALS_CALIB_DEC_MIN;
> > +
> > + /* Return max decimal if decimal above maximum */
> > + if (val2 > AP3216C_ALS_CALIB_DEC_MAX)
> > + return AP3216C_ALS_CALIB_DEC_MAX;
> > +
> > + return val2;
> > +}
> > +
> > +static int ap3216c_write_raw(struct iio_dev *indio_dev,
> > + struct iio_chan_spec const *chan,
> > + int val, int val2, long mask)
> > +{
> > + struct ap3216c_data *data = iio_priv(indio_dev);
> > + int integral, decimal;
> > + int tmp;
> > + int ret;
> > +
> > + switch (mask) {
> > + case IIO_CHAN_INFO_CALIBSCALE:
> > + switch (chan->type) {
> > + case IIO_LIGHT:
> > + integral = ap3216c_als_calibscale_int(val);
> > + decimal = ap3216c_als_calibscale_dec(val, val2);
> > +
> > + tmp = integral << AP3216C_ALS_CALIB_INT_SHIFT;
> > +
> > + /*
> > + * Reverse scaling by multiplying by the scaling
> > + * denominator and dividing by IIO multiplier.
> > + */
> > + tmp |= (decimal * AP3216C_ALS_CALIB_DENOM) /
> > + AP3216C_IIO_MULT;
> > +
> > + return regmap_write(data->regmap,
> > + AP3216C_ALS_CALIB, tmp);
> > +
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + case IIO_CHAN_INFO_CALIBBIAS:
> > + switch (chan->type) {
> > + case IIO_PROXIMITY:
> > + ret = regmap_write(data->regmap, AP3216C_PS_CALIB_LO,
> > + val & AP3216C_PS_CALIB_LO_MASK);
> > + if (ret < 0)
> > + return ret;
> > +
> > + tmp = (val & AP3216C_PS_CALIB_HI_MASK) >>
> > + AP3216C_PS_CALIB_HI_SHIFT;
regmap_bulk_write perhaps?
> > +
> > + return regmap_write(data->regmap,
> > + AP3216C_PS_CALIB_HI, tmp);
> > +
> > + default:
> > + return -EINVAL;
> > + }
> > + default:
> > + return -EINVAL;
> > + }

This final return should be unneeded.

> > + return -EINVAL;
> > +}
> > +
> > +static int ap3216c_read_raw(struct iio_dev *indio_dev,
> > + struct iio_chan_spec const *chan,
> > + int *val, int *val2, long mask)
> > +{
> > + struct ap3216c_data *data = iio_priv(indio_dev);
> > + int lo, hi;
> > + int cfg, tmp;
> > + int ret;
> > +
> > + switch (mask) {
> > + case IIO_CHAN_INFO_CALIBSCALE:
> > + switch (chan->type) {
> > + case IIO_LIGHT:
> > + ret = regmap_read(data->regmap,
> > + AP3216C_ALS_CALIB, &tmp);
> > + if (ret < 0)
> > + return ret;
> > +
> > + /* Scale is multiplied by 1/64 */
> > + *val = tmp;
> > + *val2 = AP3216C_ALS_CALIB_DENOM;
> > + return IIO_VAL_FRACTIONAL;
> > +
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + case IIO_CHAN_INFO_CALIBBIAS:
> > + switch (chan->type) {
> > + case IIO_PROXIMITY:

regmap_read_bulk should get you both in one call with concurrency protection
as an added bonus.

> > + ret = regmap_read(data->regmap,
> > + AP3216C_PS_CALIB_LO, &lo);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = regmap_read(data->regmap,
> > + AP3216C_PS_CALIB_HI, &hi);
> > + if (ret < 0)
> > + return ret;
> > +
> > +
> > + *val = lo | (hi << AP3216C_PS_CALIB_HI_SHIFT);

lo should probably be masked. Bits are documented as reserved, not 0 as
far as I can see.

> > + return IIO_VAL_INT;
> > +
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + case IIO_CHAN_INFO_PROCESSED:
> > + switch (chan->type) {
> > + case IIO_LIGHT:
> > + ret = regmap_read(data->regmap,
> > + AP3216C_ALS_DATA_LO, &lo);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = regmap_read(data->regmap,
> > + AP3216C_ALS_DATA_HI, &hi);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = regmap_read(data->regmap,
> > + AP3216C_ALS_CFG, &cfg);
> > + if (ret < 0)
> > + return ret;
> > +
> > + tmp = (hi << AP3216C_ALS_DATA_HI_SHIFT) | lo;
> > + tmp *= ap3216c_gain_array[cfg & AP3216C_ALS_CFG_GAIN_MASK];
> > +
> > + *val = tmp;
> > + *val2 = AP3216C_ALS_DATA_DENOM;
> > +
> > + return IIO_VAL_FRACTIONAL;
> > + default:
> > + return -EINVAL;
> > + }
> > + case IIO_CHAN_INFO_RAW:
> > + switch (chan->type) {
> > + case IIO_LIGHT:
> > + if (chan->channel2 != IIO_MOD_LIGHT_IR)
> > + return -EINVAL;
> > +
> > + ret = regmap_read(data->regmap,
> > + AP3216C_IR_DATA_LO, &lo);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = regmap_read(data->regmap,
> > + AP3216C_IR_DATA_HI, &hi);
> > + if (ret < 0)
> > + return ret;
> > +
> > + tmp = lo & AP3216C_IR_DATA_LO_MASK;
> > + tmp |= hi << AP3216C_IR_DATA_HI_SHIFT;
> > + *val = tmp;
> > +
> > + return IIO_VAL_INT;
> > +
> > + case IIO_PROXIMITY:
> > + ret = regmap_read(data->regmap,
> > + AP3216C_PS_DATA_LO, &lo);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = regmap_read(data->regmap,
> > + AP3216C_PS_DATA_HI, &hi);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = regmap_read(data->regmap,
> > + AP3216C_PS_CFG, &cfg);
> > + if (ret < 0)
> > + return ret;
> > +
> > + tmp = lo & AP3216C_PS_DATA_LO_MASK;
> > + tmp |= (hi & AP3216C_PS_DATA_HI_MASK) <<
> > + AP3216C_PS_DATA_HI_SHIFT;
> > + *val = tmp * AP3216C_PS_CFG_GAIN(cfg);
> > +
> > + return IIO_VAL_INT;
> > + default:
> > + return -EINVAL;
> > + }
> > + default:
> > + return -EINVAL;
> > + }
> > + return -EINVAL;
> > +}
> > +
> > +static const struct iio_info ap3216c_info = {
> > + .read_raw = ap3216c_read_raw,
> > + .write_raw = ap3216c_write_raw,
> > + .read_event_value = ap3216c_read_event_value,
> > + .write_event_value = ap3216c_write_event_value,
> > + .read_event_config = ap3216c_read_event_config,
> > + .write_event_config = ap3216c_write_event_config,
> > +};
> > +
> > +static int ap3216c_clear_int(struct ap3216c_data *data)
> > +{
> > + return regmap_write(data->regmap,
> > + AP3216C_INT_STATUS, AP3216C_INT_STATUS_CLR);
> > +}
> > +
> > +static irqreturn_t ap3216c_event_handler(int irq, void *p)
> > +{
> > + struct iio_dev *indio_dev = p;
> > + struct ap3216c_data *data = iio_priv(indio_dev);
> > + int status;
> > + s64 timestamp;
> > + int ret;
> > +
> > + ret = regmap_read(data->regmap, AP3216C_INT_STATUS, &status);
> > + if (ret) {
> > + /*
> > + * Without being able to guarantee the interrupt came from
> > + * this device, we must return IRQ_HANDLED instead of
> > + * IRQ_NONE.
> > + */
>
> Do you know why? I'm not saying this is wrong, just curious to know why.
> Because if the chip becomes unresponsive, now the driver will consume
> all interrupts on the shared interrupt line, right ?
>
> > + dev_err(&data->client->dev, "error reading IRQ status\n");
> > + return IRQ_HANDLED;
> > + }
> > +
> > + /* The IRQ was not from this device */
> > + if (!status)
> > + return IRQ_NONE;
> > +
> > + timestamp = iio_get_time_ns(indio_dev);
> > + if ((status & AP3216C_INT_STATUS_PS_MASK) && data->prox_thresh_en)
> > + iio_push_event(indio_dev,
> > + IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY, 0,
> > + IIO_EV_TYPE_THRESH,
> > + IIO_EV_DIR_EITHER),
> > + timestamp);
> > +
> > + if ((status & AP3216C_INT_STATUS_ALS_MASK) && data->als_thresh_en)
> > + iio_push_event(indio_dev,
> > + IIO_UNMOD_EVENT_CODE(IIO_LIGHT, 0,
> > + IIO_EV_TYPE_THRESH,
> > + IIO_EV_DIR_EITHER),
> > + timestamp);
>
> I'm a complete newbie re. this driver and the iio subsystem in general, but I
> suspect that events could be lost here:
>
> Example flow:
> 1. device generates ALS data, writes it to the register, asserts interrupt
> 2. this event handler executes, it's a threaded event handler, so may be
> interleaved with userspace threads
> 3. this event handler calls iio_push_event() and is then paused by the scheduler
> 4. a userspace thread monitoring the iio interface reacts to to the event,
> and reads the ALS data
> 5. the device generates _new_ ALS data, interrupt already asserted
> 6. the threaded event handler continues executing, clears the interrupt
>
> Result: new ALS data is available, but iio did not get an event ?
>
> If this is indeed an issue, you might be able to address this by locking
> the interrupt handler and ALS/PS read with a mutex ?
>
> But of course if you do that, you might end up with an interrupt / event
> for a value you've already read out. That's fine only if iio core is ok with
> spurious events.

I may be missing something. That datasheet isn't the clearest I've
ever seen...

I think this device is running in a self clocked mode if we are running
with events.

So an additional read will not result in an additional event.

Also the interrupt is latching. If we get a repeat of the same event
it is generally of no interest to userspace. If it's a different
event we'll get an additional bit latched.

So yes, it's more than possible that userspace won't get the same number
of events as samples taken over the limit, but I don't know why we care.
We can about missing a threshold being passed entirely, not about knowing
how many samples we were above it for.

>
> > +
> > + ret = ap3216c_clear_int(data);
> > + if (ret < 0)
> > + dev_err(&data->client->dev, "error clearing IRQ\n");
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static int ap3216c_probe(struct i2c_client *client,
> > + const struct i2c_device_id *id)
> > +{
> > + struct ap3216c_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);
> > + data->client = client;
> > + indio_dev->dev.parent = &client->dev;
> > + indio_dev->info = &ap3216c_info;
> > + indio_dev->name = AP3216C_DRV_NAME;
> > + indio_dev->channels = ap3216c_channels;
> > + indio_dev->num_channels = ARRAY_SIZE(ap3216c_channels);
> > +
> > + data->regmap = devm_regmap_init_i2c(client, &ap3216c_regmap_config);
> > + if (IS_ERR(data->regmap)) {
> > + dev_err(&client->dev, "Failed to allocate register map\n");
> > + return PTR_ERR(data->regmap);
> > + }
> > +
> > + /* Default to thresh events disabled */
> > + data->als_thresh_en = false;
> > + data->prox_thresh_en = false;
> > +
> > + /*
> > + * Require that that the interrupt is cleared only when the INT
> > + * register is written to, instead of when data is read. This
> > + * prevents the interrupt from falsely reporting IRQ_NONE.
> > + */
> > + ret = regmap_write(data->regmap,
> > + AP3216C_INT_CLR, AP3216C_INT_CLR_MANUAL);
> > + if (ret < 0)
> > + return ret;
> > +
> > + /* Before setting up IRQ, clear any stale interrupt */
> > + ret = ap3216c_clear_int(data);
> > + if (ret < 0)
> > + return ret;
> > +
> > + if (client->irq) {
> > + ret = devm_request_threaded_irq(&client->dev, client->irq,
> > + NULL, ap3216c_event_handler,
> > + IRQF_TRIGGER_FALLING |
> > + IRQF_SHARED | IRQF_ONESHOT,
> > + client->name, indio_dev);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + /* Enable ALS and PS+IR */
> > + ret = regmap_write(data->regmap, AP3216C_SYS, AP3216C_SYS_MODE_ALS_PS);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return devm_iio_device_register(&client->dev, indio_dev);
> > +}
> > +
> > +static const struct of_device_id ap3216c_of_match[] = {
> > + { .compatible = "liteon,ap3216c", },
> > + { },
> > +};
> > +MODULE_DEVICE_TABLE(of, ap3216c_of_match);
> > +
> > +static const struct i2c_device_id ap3216c_id[] = {
> > + {"ap3216c", 0},
> > + { }
> > +};
> > +MODULE_DEVICE_TABLE(i2c, ap3216c_id);
> > +
> > +static struct i2c_driver ap3216c_driver = {
> > + .driver = {
> > + .name = AP3216C_DRV_NAME,
> > + },
> > + .probe = ap3216c_probe,
> > + .id_table = ap3216c_id,
> > +};
> > +module_i2c_driver(ap3216c_driver);
> > +
> > +MODULE_AUTHOR("Robert Eshleman <bobbyeshleman@gmail.com>");
> > +MODULE_DESCRIPTION("APC3216C Ambient Light and Proximity Sensor");
> > +MODULE_LICENSE("GPL v2");
> > --
> > 2.20.1
> >

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