Re: [PATCH v2 1/3] iio: light: Add driver for ap3216c

[Sven Van Asbroeck]

Hi, comments inline.

On Sun, Feb 24, 2019 at 3:36 PM Robert Eshleman <bobbyeshleman@xxxxxxxxx> wrote:
>
>     This patch adds support for the ap3216c ambient light and proximity
>     sensor.
>
>     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@xxxxxxxxx>
> ---
> Changes in v2:
> - Add mutex protection in IRQ handler
> - Support interrupt clearing for PS and ALS separately
> - Mask away reserved bits when reading device registers
> - Use regmap_bulk_read and regmap_bulk_write when possible
> - Style cleanup
>
>  drivers/iio/light/Kconfig   |  11 +
>  drivers/iio/light/Makefile  |   1 +
>  drivers/iio/light/ap3216c.c | 809 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 821 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..aaa319b932e6
> --- /dev/null
> +++ b/drivers/iio/light/ap3216c.c
> @@ -0,0 +1,809 @@
> +// 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 0x3
> +
> +/* INT_STATUS masks and config value */
> +#define AP3216C_INT_STATUS_ALS_MASK BIT(0)
> +#define AP3216C_INT_STATUS_PS_MASK BIT(1)

these are identical to PS_CLR, ALS_CLR?
maybe just use AP3216C_INT_STATUS_[PS|ALS] for both?

> +#define AP3216C_INT_STATUS_CLR GENMASK(1, 0)

unused?

> +#define AP3216C_INT_ALS_CLR BIT(0)
> +#define AP3216C_INT_PS_CLR BIT(1)
> +#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)
> +#define AP3216C_ALS_CFG_GAIN_SHIFT 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(16, 8)
> +#define AP3216C_ALS_HI_THR_HI_READ_MASK GENMASK(7, 0)
> +#define AP3216C_ALS_HI_THR_HI_SHIFT 8
> +
> +#define AP3216C_ALS_THR_HI_SHIFT 8
> +
> +/* ALS_LO_THR masks and shifts */
> +#define AP3216C_ALS_LO_THR_LO_MASK GENMASK(7, 0)
> +#define AP3216C_ALS_LO_THR_HI_MASK GENMASK(16, 8)
> +#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 multiplier values */
> +#define AP3216C_PS_LO_THR_HI_MULT 4
> +#define AP3216C_PS_HI_THR_HI_MULT 4
> +#define AP3216C_PS_THR_HI_MULT 4
> +
> +/* PS_THR_LO and PS_THR_HI masks/shifts */
> +#define AP3216C_PS_THR_LO_MASK GENMASK(1, 0)
> +#define AP3216C_PS_THR_HI_MASK GENMASK(10, 2)
> +#define AP3216C_PS_THR_HI_SHIFT 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 1000
> +#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
> +#define AP3216C_PS_THR_MAX (BIT(10) - 1)
> +
> +/* See ALS configuration ALS_GAIN field in datasheet */
> +#define AP3216C_ALS_THR_MAX 20661
> +
> +static const u16 ap3216c_gain_array[] = {
> +       3500,  /* 0.3500 lux resolution */
> +        788,  /* 0.0788 lux resolution */
> +        197,  /* 0.0197 lux resolution */
> +         49,  /* 0.0049 lux resolution */
> +};
> +
> +static const u16 ap3216c_als_max_thr_array[] = {
> +       20661,  /* max thr when gain is 0.3500 */
> +        5162,  /* max thr when gain is 0.0788 */
> +        1291,  /* max thr when gain is 0.0197 */
> +         323,  /* max thr when gain is 0.0049*/
> +};
> +
> +struct ap3216c_data {
> +       struct regmap *regmap;
> +       struct i2c_client *client;
> +       struct mutex lock;
> +       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_read_gain(struct ap3216c_data *data, u16 *gain)
> +{
> +       unsigned int cfg;
> +       int ret;
> +
> +       ret = regmap_read(data->regmap, AP3216C_ALS_CFG, &cfg);
> +       if (ret < 0)
> +               return ret;
> +
> +       *gain = ap3216c_gain_array[(cfg & AP3216C_ALS_CFG_GAIN_MASK) >>
> +                                   AP3216C_ALS_CFG_GAIN_SHIFT];
> +       return 0;
> +}
> +
> +static int ap3216c_read_max_thr(struct ap3216c_data *data, u16 *max_thr)
> +{
> +       unsigned int cfg;
> +       int ret;
> +
> +       ret = regmap_read(data->regmap, AP3216C_ALS_CFG, &cfg);
> +       if (ret < 0)
> +               return ret;
> +
> +       /* max thr is derived from the gain bits of ALS_CFG */
> +       *max_thr = ap3216c_als_max_thr_array[
> +                       (cfg & AP3216C_ALS_CFG_GAIN_MASK) >>
> +                        AP3216C_ALS_CFG_GAIN_SHIFT];
> +       return 0;
> +}
> +
> +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);
> +       u8 vals[2];
> +       int integral, fractional;
> +       u16 thr, max_thr, gain;
> +       int ret;
> +
> +       if (val < 0 || val2 < 0)
> +               return -EINVAL;
> +
> +       switch (chan->type) {
> +       case IIO_LIGHT:
> +               ret = ap3216c_read_max_thr(data, &max_thr);
> +               if (ret < 0)
> +                       return ret;
> +
> +               if (val > max_thr)
> +                       val = max_thr;
> +
> +               ret = ap3216c_read_gain(data, &gain);
> +               if (ret < 0)
> +                       return ret;
> +
> +               integral = val * AP3216C_ALS_INTEG_MULT / gain;
> +               fractional = val2 / AP3216C_ALS_FRACT_DIV / gain;
> +
> +               thr = integral + fractional;
> +
> +               switch (dir) {
> +               case IIO_EV_DIR_RISING:
> +                       vals[0] = thr & AP3216C_ALS_HI_THR_LO_MASK;
> +                       vals[1] = (thr & AP3216C_ALS_HI_THR_HI_MASK) >>
> +                                  AP3216C_ALS_HI_THR_HI_SHIFT;
> +
> +                       return regmap_bulk_write(data->regmap,
> +                                                AP3216C_ALS_HI_THR_LO,
> +                                                vals, 2);
> +
> +               case IIO_EV_DIR_FALLING:
> +                       vals[0] = thr & AP3216C_ALS_LO_THR_LO_MASK;
> +                       vals[1] = (thr & AP3216C_ALS_LO_THR_HI_MASK) >>
> +                                  AP3216C_ALS_LO_THR_HI_SHIFT;
> +
> +                       return regmap_bulk_write(data->regmap,
> +                                                AP3216C_ALS_LO_THR_LO,
> +                                                vals, 2);
> +               default:
> +                       return -EINVAL;
> +               }
> +
> +
> +       case IIO_PROXIMITY:
> +               if (val > AP3216C_PS_THR_MAX)
> +                       val = AP3216C_PS_THR_MAX;
> +
> +               vals[0] = val & AP3216C_PS_THR_LO_MASK;
> +               vals[1] = (val & AP3216C_PS_THR_HI_MASK) >>
> +                          AP3216C_PS_THR_HI_SHIFT;
> +
> +               switch (dir) {
> +               case IIO_EV_DIR_RISING:
> +                       return regmap_bulk_write(data->regmap,
> +                                                AP3216C_PS_HI_THR_LO,
> +                                                vals, 2);
> +
> +               case IIO_EV_DIR_FALLING:
> +                       return regmap_bulk_write(data->regmap,
> +                                                AP3216C_PS_LO_THR_LO,
> +                                                vals, 2);
> +               default:
> +                       return -EINVAL;
> +               }
> +
> +       default:
> +               return -EINVAL;
> +       }
> +}
> +
> +static int ap3216c_get_als_reg(enum iio_event_direction dir)
> +{
> +       switch (dir) {
> +       case IIO_EV_DIR_RISING:
> +               return AP3216C_ALS_HI_THR_LO;
> +
> +       case IIO_EV_DIR_FALLING:
> +               return AP3216C_ALS_LO_THR_LO;
> +
> +       default:
> +               return -EINVAL;
> +       }
> +}
> +
> +static int ap3216c_get_ps_reg(enum iio_event_direction dir)
> +{
> +       switch (dir) {
> +       case IIO_EV_DIR_RISING:
> +               return AP3216C_PS_HI_THR_LO;
> +
> +       case IIO_EV_DIR_FALLING:
> +               return AP3216C_PS_LO_THR_LO;
> +
> +       default:
> +               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);
> +       u16 gain;
> +       u8 vals[2];
> +       int reg, ret;
> +
> +       switch (chan->type) {
> +       case IIO_LIGHT:
> +               reg = ap3216c_get_als_reg(dir);
> +               if (reg < 0)
> +                       return reg;
> +
> +               ret = regmap_bulk_read(data->regmap, reg, vals, 2);
> +               if (ret < 0)
> +                       return ret;
> +
> +               ret = ap3216c_read_gain(data, &gain);
> +               if (ret < 0)
> +                       return ret;
> +
> +               *val = ((vals[1] << AP3216C_ALS_THR_HI_SHIFT) | vals[0]) *
> +                        gain / AP3216C_ALS_INTEG_MULT;
> +               return IIO_VAL_INT;
> +
> +       case IIO_PROXIMITY:
> +               reg = ap3216c_get_ps_reg(dir);
> +               if (reg < 0)
> +                       return reg;
> +
> +               ret = regmap_bulk_read(data->regmap, reg, vals, 2);
> +               if (ret < 0)
> +                       return ret;
> +
> +               *val = (vals[1] << 2) | (vals[0] & AP3216C_PS_THR_LO_MASK);
> +
> +               return IIO_VAL_INT;
> +
> +       default:
> +               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);
> +       int ret;
> +
> +       mutex_lock(&data->lock);
> +       switch (chan->type) {
> +       case IIO_LIGHT:
> +               ret = data->als_thresh_en;
> +               break;
> +
> +       case IIO_PROXIMITY:
> +               ret = data->prox_thresh_en;
> +               break;
> +
> +       default:
> +               ret = -EINVAL;
> +               break;
> +       }
> +       mutex_unlock(&data->lock);
> +
> +       return ret;
> +}
> +
> +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);
> +       int ret = 0;
> +
> +       mutex_lock(&data->lock);
> +       switch (chan->type) {
> +       case IIO_LIGHT:

is it ok to allow userspace to set thresh_en = 1, even if the chip's irq line
is not connected ? (client->irq == 0) ?

> +               data->als_thresh_en = state;
> +               break;
> +
> +       case IIO_PROXIMITY:
> +               data->prox_thresh_en = state;
> +               break;
> +
> +       default:
> +               ret = -EINVAL;
> +               break;
> +       }
> +       mutex_unlock(&data->lock);
> +
> +       return ret;
> +}
> +
> +static const struct regmap_config ap3216c_regmap_config = {
> +       .reg_bits = 8,
> +       .val_bits = 8,
> +       .max_register = AP3216C_PS_HI_THR_HI,
> +};

IMHO using this config, bulk_read may default to raw_read, i.e.
bulk_read(regmap, ALS_DATA_LO, vals, 2) may result in a 2-byte read from
ALS_DATA_LO. but looking at the datasheet page 9 (i2c read / read combined)
this i2c mode doesn't appear to be documented? the docs imply we should do:
single-byte read from ALS_DATA_LO, followed by single-byte read from
ALS_DATA_HI.

maybe this works by accident?
perhaps force the regmap core to follow the chip datasheet explicitly by adding
       .use_single_rw = true,
?

> +
> +/**
> + * 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;
> +       u8 vals[2];
> +       int tmp;
> +
> +       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:
> +                       vals[0] = val & AP3216C_PS_CALIB_LO_MASK;
> +                       vals[1] = (val & AP3216C_PS_CALIB_HI_MASK) >>
> +                                  AP3216C_PS_CALIB_HI_SHIFT;
> +
> +                       return regmap_bulk_write(data->regmap,
> +                                                AP3216C_PS_CALIB_LO,
> +                                                vals, 2);
> +
> +               default:
> +                       return -EINVAL;
> +               }
> +       default:
> +               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);
> +       u16 gain;
> +       u8 vals[2];
> +       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:
> +                       ret = regmap_bulk_read(data->regmap,
> +                                              AP3216C_PS_CALIB_LO,
> +                                              vals, 2);
> +                       if (ret < 0)
> +                               return ret;
> +
> +                       *val = (vals[0] & AP3216C_PS_CALIB_LO_MASK) |
> +                              ((vals[1] & AP3216C_PS_CALIB_HI_MASK) <<
> +                               AP3216C_PS_CALIB_HI_SHIFT);
> +
> +                       return IIO_VAL_INT;
> +
> +               default:
> +                       return -EINVAL;
> +               }
> +
> +       case IIO_CHAN_INFO_PROCESSED:
> +               switch (chan->type) {
> +               case IIO_LIGHT:
> +                       ret = regmap_bulk_read(data->regmap,
> +                                              AP3216C_ALS_DATA_LO,
> +                                              vals, 2);
> +                       if (ret < 0)
> +                               return ret;
> +
> +                       ret = ap3216c_read_gain(data, &gain);
> +                       if (ret < 0)
> +                               return ret;
> +
> +                       *val = ((vals[1] << AP3216C_ALS_DATA_HI_SHIFT) |
> +                                vals[0]) * gain;
> +                       *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_bulk_read(data->regmap,
> +                                              AP3216C_IR_DATA_LO,
> +                                              vals, 2);

maybe add a comment that [IR|ALS|PS]_DATA_[HI_LO] registers are 'special':
they have to be read in the correct order, and atomically, and document
that bulk_read() currently satisfies those requirements ?

otherwise this is easy to forget - even for our future selves :)

> +
> +                       *val = (vals[0] & AP3216C_IR_DATA_LO_MASK) |
> +                              (vals[1] << AP3216C_IR_DATA_HI_SHIFT);
> +
> +
> +                       return IIO_VAL_INT;
> +
> +               case IIO_PROXIMITY:
> +                       ret = regmap_bulk_read(data->regmap,
> +                                              AP3216C_PS_DATA_LO,
> +                                              vals, 2);
> +                       if (ret < 0)
> +                               return ret;
> +
> +                       ret = regmap_read(data->regmap,
> +                                         AP3216C_PS_CFG, &cfg);
> +                       if (ret < 0)
> +                               return ret;
> +
> +                       tmp = vals[0] & AP3216C_PS_DATA_LO_MASK;
> +                       tmp |= (vals[1] & 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;
> +       }
> +}
> +
> +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 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;
> +
> +       mutex_lock(&data->lock);

IMHO the discussion between Jonathan & myself on your v1 patch ended with the
conclusion that a mutex isn't needed for visibility here - the mutex in kernfs
will ensure this. So there was consensus that the mutex here is not needed.

> +       ret = regmap_read(data->regmap, AP3216C_INT_STATUS, &status);
> +       if (ret) {
> +               dev_err(&data->client->dev, "error reading IRQ status\n");
> +               goto done;
> +       }
> +
> +       /* The IRQ was not from this device */
> +       if (!status) {
> +               mutex_unlock(&data->lock);
> +               return IRQ_NONE;
> +       }
> +
> +       timestamp = iio_get_time_ns(indio_dev);
> +       if (status & AP3216C_INT_STATUS_PS_MASK) {
> +               if (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);
> +
> +               ret = regmap_write(data->regmap,
> +                                  AP3216C_INT_STATUS, AP3216C_INT_PS_CLR);
> +               if (ret < 0)
> +                       dev_err(&data->client->dev, "error clearing PS interrupt\n");
> +       }
> +
> +       if (status & AP3216C_INT_STATUS_ALS_MASK) {
> +               if (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);
> +
> +               ret = regmap_write(data->regmap,
> +                                  AP3216C_INT_STATUS, AP3216C_INT_ALS_CLR);
> +               if (ret < 0)
> +                       dev_err(&data->client->dev, "error clearing ALS interrupt\n");
> +       }
> +
> +done:
> +       mutex_unlock(&data->lock);
> +       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;
> +       mutex_init(&data->lock);
> +       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_STATUS
> +        * register is written to, instead of when data is read.
> +        */
> +       ret = regmap_write(data->regmap,
> +                          AP3216C_INT_CLR, AP3216C_INT_CLR_MANUAL);
> +       if (ret < 0)
> +               return ret;
> +
> +       ret = regmap_write(data->regmap, AP3216C_INT_STATUS,
> +                          AP3216C_INT_PS_CLR | AP3216C_INT_ALS_CLR);
> +       if (ret < 0) {
> +               dev_err(&data->client->dev, "error clearing interrupts\n");
> +               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@xxxxxxxxx>");
> +MODULE_DESCRIPTION("AP3216C Ambient Light and Proximity Sensor");
> +MODULE_LICENSE("GPL v2");
> --
> 2.20.1
>