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In-Reply-To: <20191022110000.28b7d2c5@archlinux>
From:   rishi gupta <gupt21@gmail.com>
Date:   Tue, 22 Oct 2019 18:02:51 +0530
Message-ID: <CALUj-guR0XBGLCx2WnTSGiaVPpKbPcSKNVhbb+N8VfS449_NJg@mail.gmail.com>
Subject: Re: [PATCH v4 1/3] iio: light: add driver for veml6030 ambient light sensor
To:     Jonathan Cameron <jic23@kernel.org>
Cc:     knaack.h@gmx.de, lars@metafoo.de,
        Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
        gregkh@linuxfoundation.org, tglx@linutronix.de,
        allison@lohutok.net, alexios.zavras@intel.com, angus@akkea.ca,
        linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
        robh+dt@kernel.org, mark.rutland@arm.com,
        devicetree@vger.kernel.org
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Sender: linux-kernel-owner@vger.kernel.org
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Thanks Jonathan, sorry for deep thread, learnt will keep in mind.

All suggested changes done except re-ordering devm_add_action_or_reset.
Please see inline and suggest if I missed something.

On Tue, Oct 22, 2019 at 3:30 PM Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Tue, 22 Oct 2019 09:27:15 +0530
> Rishi Gupta <gupt21@gmail.com> wrote:
>
> > veml6030 is an ambient light sensor from Vishay semiconductors.
> > It has 16-bit resolution, supports both ambient light measurement
> > and white channel which is more responsive to wider wavelength
> > spectrum. It has flexible power saving, integration time and
> > gain options. Communication with host is over I2C.
> >
> > Signed-off-by: Rishi Gupta <gupt21@gmail.com>
>
> Please avoid this complex nested replies to old patches.
> New version of a series should be a new thread.
>
> It's much easier for myself or others to be sure they have the latest version
> than when they are interleaved like this.
>
> I've raised ABI concerns in patch 3, so won't repeat that here
>
> Various minor other things inline.
>
> Jonathan
>
> > ---
> > Changes in v4:
> > * None
> >
> > Changes in v3:
> > * Added appnote link in topmost comments section
> > * Dropped 'return ret' statements wherever not needed
> > * Removed .scan_index from channel specifications, not needed
> > * If irq is not enabled, events interfaces are not exposed now
> > * Return IRQ_NONE for spurious interrupt
> > * Removed CONFIG_PM, added __maybe_unused in power routines
> > * Removed of_match_ptr when specifying DT device id to match
> > * Corrected & documented sequence in veml6030_write_interrupt_config()
> > * Removed veml6030_remove() & added devm_add_action_or_reset functionality
> > * Added support to read integration time, gain, thresholds, period
> > * Removed including mutex.h not needed
> > * Set 100 ms integration & 1/8 gain during probe for better accuracy
> > * Used IIO_CONST_ATTR to create sysfs entries "_available"
> > * Minor cosmetics like everything in lower case
> >
> > Changes in v2:
> > * Added comma after CH_WHITE in enum veml6030_chan so it can be extended
> > * Removed .scan_type as driver doesn't use buffered mode
> > * Removed iio_device_unregister() as kernel will take care of cleaning
> >
> >  drivers/iio/light/Kconfig    |  11 +
> >  drivers/iio/light/Makefile   |   1 +
> >  drivers/iio/light/veml6030.c | 903 +++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 915 insertions(+)
> >  create mode 100644 drivers/iio/light/veml6030.c
> >
> > diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
> > index 4a1a883..f9d27ef 100644
> > --- a/drivers/iio/light/Kconfig
> > +++ b/drivers/iio/light/Kconfig
> > @@ -496,6 +496,17 @@ config VCNL4035
> >         To compile this driver as a module, choose M here: the
> >         module will be called vcnl4035.
> >
> > +config VEML6030
> > +     tristate "VEML6030 ambient light sensor"
> > +     select REGMAP_I2C
> > +     depends on I2C
> > +     help
> > +       Say Y here if you want to build a driver for the Vishay VEML6030
> > +       ambient light sensor (ALS).
> > +
> > +       To compile this driver as a module, choose M here: the
> > +       module will be called veml6030.
> > +
> >  config VEML6070
> >       tristate "VEML6070 UV A light sensor"
> >       depends on I2C
> > diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
> > index 00d1f9b..5e0c40b 100644
> > --- a/drivers/iio/light/Makefile
> > +++ b/drivers/iio/light/Makefile
> > @@ -48,6 +48,7 @@ obj-$(CONFIG_TSL4531)               += tsl4531.o
> >  obj-$(CONFIG_US5182D)                += us5182d.o
> >  obj-$(CONFIG_VCNL4000)               += vcnl4000.o
> >  obj-$(CONFIG_VCNL4035)               += vcnl4035.o
> > +obj-$(CONFIG_VEML6030)               += veml6030.o
> >  obj-$(CONFIG_VEML6070)               += veml6070.o
> >  obj-$(CONFIG_VL6180)         += vl6180.o
> >  obj-$(CONFIG_ZOPT2201)               += zopt2201.o
> > diff --git a/drivers/iio/light/veml6030.c b/drivers/iio/light/veml6030.c
> > new file mode 100644
> > index 0000000..d0d4e42
> > --- /dev/null
> > +++ b/drivers/iio/light/veml6030.c
> > @@ -0,0 +1,903 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * VEML6030 Ambient Light Sensor
> > + *
> > + * Copyright (c) 2019, Rishi Gupta <gupt21@gmail.com>
> > + *
> > + * Datasheet: https://www.vishay.com/docs/84366/veml6030.pdf
> > + * Appnote-84367: https://www.vishay.com/docs/84367/designingveml6030.pdf
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/i2c.h>
> > +#include <linux/err.h>
> > +#include <linux/regmap.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/pm_runtime.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/iio/sysfs.h>
> > +#include <linux/iio/events.h>
> > +
> > +/* Device registers */
> > +#define VEML6030_REG_ALS_CONF   0x00
> > +#define VEML6030_REG_ALS_WH     0x01
> > +#define VEML6030_REG_ALS_WL     0x02
> > +#define VEML6030_REG_ALS_PSM    0x03
> > +#define VEML6030_REG_ALS_DATA   0x04
> > +#define VEML6030_REG_WH_DATA    0x05
> > +#define VEML6030_REG_ALS_INT    0x06
> > +
> > +/* Bit masks for specific functionality */
> > +#define VEML6030_ALS_IT       GENMASK(9, 6)
> > +#define VEML6030_PSM          GENMASK(2, 1)
> > +#define VEML6030_ALS_PERS     GENMASK(5, 4)
> > +#define VEML6030_ALS_GAIN     GENMASK(12, 11)
> > +#define VEML6030_PSM_EN       BIT(0)
> > +#define VEML6030_INT_TH_LOW   BIT(15)
> > +#define VEML6030_INT_TH_HIGH  BIT(14)
> > +#define VEML6030_ALS_INT_EN   BIT(1)
> > +#define VEML6030_ALS_SD       BIT(0)
> > +
> > +/*
> > + * The resolution depends on both gain and integration time. The
> > + * cur_resolution stores one of the resolution mentioned in the
> > + * table during startup and gets updated whenever integration time
> > + * or gain is changed.
> > + *
> > + * Table 'resolution and maximum detection range' in appnote 84367
> > + * is visualized as a 2D array. The cur_gain stores index of gain
> > + * in this table (0-3) while the cur_integration_time holds index
> > + * of integration time (0-5).
> > + */
> > +struct veml6030_data {
> > +     struct i2c_client *client;
> > +     struct regmap *regmap;
> > +     int cur_resolution;
> > +     int cur_gain;
> > +     int cur_integration_time;
> > +};
> > +
> > +/* Integration time available in seconds */
> > +static IIO_CONST_ATTR(in_illuminance_integration_time_available,
> > +                             "0.025 0.05 0.1 0.2 0.4 0.8");
> > +
> > +/*
> > + * Scale is 1/gain. Value 0.125 is ALS gain x (1/8), 0.25 is
> > + * ALS gain x (1/4), 1.0 = ALS gain x 1 and 2.0 is ALS gain x 2.
> > + */
> > +static IIO_CONST_ATTR(in_illuminance_scale_available,
> > +                             "0.125 0.25 1.0 2.0");
> > +
> > +/*
> > + * Power saving modes 1/2/3/4.
> > + * Products can achieve a trade-off between power savings and
> > + * frequency of als latest readings available through psm.
> > + */
> > +static IIO_CONST_ATTR(in_illuminance_psm_available,
> > +                             "1 2 3 4");
> > +
> > +static ssize_t in_illuminance_psm_store(struct device *dev,
> > +                                             struct device_attribute *attr,
> > +                                             const char *buf, size_t len)
> > +{
> > +     int ret;
> > +     unsigned int val;
> > +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     if (kstrtouint(buf, 0, &val))
> > +             return -EINVAL;
> > +
> > +     if (val < 1 || val > 4)
> > +             return -EINVAL;
> > +
> > +     /* update bits 1-2 */
> > +     val = ((val - 1) << 1);
> > +
> > +     ret = regmap_update_bits(data->regmap, VEML6030_REG_ALS_PSM,
> > +                                     VEML6030_PSM, val);
> > +     if (ret) {
> > +             dev_err(&data->client->dev,
> > +                             "can't update psm value %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     return len;
> > +}
> > +
> > +static ssize_t in_illuminance_psm_show(struct device *dev,
> > +                             struct device_attribute *attr, char *buf)
> > +{
> > +     int ret, reg;
> > +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     ret = regmap_read(data->regmap, VEML6030_REG_ALS_PSM, &reg);
> > +     if (ret) {
> > +             dev_err(&data->client->dev,
> > +                             "can't read psm register %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     return sprintf(buf, "%d\n", (((reg >> 1) & 0x03) + 1));
> > +}
> > +
> > +static IIO_DEVICE_ATTR_RW(in_illuminance_psm, 0);
> > +
> > +static struct attribute *veml6030_attributes[] = {
> > +     &iio_const_attr_in_illuminance_integration_time_available.dev_attr.attr,
> > +     &iio_const_attr_in_illuminance_scale_available.dev_attr.attr,
> > +     &iio_const_attr_in_illuminance_psm_available.dev_attr.attr,
> > +     &iio_dev_attr_in_illuminance_psm.dev_attr.attr,
> > +     NULL
> > +};
> > +
> > +static const struct attribute_group veml6030_attr_group = {
> > +     .attrs = veml6030_attributes,
> > +};
> > +
> > +/*
> > + * Persistence = 1/2/4/8 x integration time
> > + * Minimum time for which light readings must stay above configured
> > + * threshold to assert interrupt.
> > + */
> > +static IIO_CONST_ATTR(in_illuminance_period_available,
> > +                             "1 2 4 8");
> > +
> > +static struct attribute *veml6030_event_attributes[] = {
> > +     &iio_const_attr_in_illuminance_period_available.dev_attr.attr,
> > +     NULL
> > +};
> > +
> > +static const struct attribute_group veml6030_event_attr_group = {
> > +     .attrs = veml6030_event_attributes,
> > +};
> > +
> > +static int veml6030_als_pwr_on(struct veml6030_data *data)
> > +{
> > +     return regmap_update_bits(data->regmap, VEML6030_REG_ALS_CONF,
> > +                              VEML6030_ALS_SD, 0);
> > +}
> > +
> > +static int veml6030_als_shut_down(struct veml6030_data *data)
> > +{
> > +     return regmap_update_bits(data->regmap, VEML6030_REG_ALS_CONF,
> > +                              VEML6030_ALS_SD, 1);
> > +}
> > +
> > +static void veml6030_als_shut_down_action(void *data)
> > +{
> > +     veml6030_als_shut_down(data);
> > +}
> > +
> > +static const struct iio_event_spec veml6030_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_separate = BIT(IIO_EV_INFO_PERIOD),
> > +     }, {
> > +             .type = IIO_EV_TYPE_THRESH,
> > +             .dir = IIO_EV_DIR_EITHER,
> > +             .mask_separate = BIT(IIO_EV_INFO_ENABLE),
> > +     },
> > +};
> > +
> > +/* Channel number */
> > +enum veml6030_chan {
> > +     CH_ALS,
> > +     CH_WHITE,
> > +};
> > +
> > +static const struct iio_chan_spec veml6030_channels[] = {
> > +     {
> > +             .type = IIO_LIGHT,
> > +             .channel = CH_ALS,
> > +             .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > +                             BIT(IIO_CHAN_INFO_PROCESSED) |
> > +                             BIT(IIO_CHAN_INFO_INT_TIME) |
> > +                             BIT(IIO_CHAN_INFO_SCALE),
> > +             .event_spec = veml6030_event_spec,
> > +             .num_event_specs = ARRAY_SIZE(veml6030_event_spec),
> > +     },
> > +     {
> > +             .type = IIO_INTENSITY,
> > +             .channel = CH_WHITE,
> > +             .modified = 1,
> > +             .channel2 = IIO_MOD_LIGHT_BOTH,
> > +             .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > +                             BIT(IIO_CHAN_INFO_PROCESSED),
> > +     },
> > +};
> > +
> > +static const struct regmap_config veml6030_regmap_config = {
> > +     .name = "veml6030_regmap",
> > +     .reg_bits = 8,
> > +     .val_bits = 16,
> > +     .max_register = VEML6030_REG_ALS_INT,
> > +     .val_format_endian = REGMAP_ENDIAN_LITTLE,
> > +};
> > +
> > +static int veml6030_read_persistence(struct iio_dev *indio_dev,
> > +                                             int *val, int *val2)
> > +{
> > +     int ret, reg;
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     ret = regmap_read(data->regmap, VEML6030_REG_ALS_CONF, &reg);
> > +     if (ret) {
> > +             dev_err(&data->client->dev,
> > +                             "can't als configuration register %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     *val = 1 << ((reg >> 3) & 0x03);
> > +     *val2 = 0;
> > +     return IIO_VAL_INT;
> > +}
> > +
> > +static int veml6030_write_persistence(struct iio_dev *indio_dev,
> > +                                             int val, int val2)
> > +{
> > +     int ret;
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     if (val < 0 || val > 8 || hweight8(val) != 1 || val2)
> > +             return -EINVAL;
> > +
> > +     ret = regmap_update_bits(data->regmap, VEML6030_REG_ALS_CONF,
> > +                                     VEML6030_ALS_PERS, val << 4);
> > +     if (ret)
> > +             dev_err(&data->client->dev,
> > +                             "can't set persistence value %d\n", ret);
> > +
> > +     return ret;
> > +}
> > +
> > +static int veml6030_set_als_gain(struct iio_dev *indio_dev,
> > +                                             int val, int val2)
> > +{
> > +     int ret, new_gain, gain_idx;
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     if (val == 0 && val2 == 125000) {
> > +             new_gain = 0x1000; /* 0x02 << 11 */
> > +             gain_idx = 3;
> > +     } else if (val == 0 && val2 == 250000) {
> > +             new_gain = 0x1800;
> > +             gain_idx = 2;
> > +     } else if (val == 1 && val2 == 0) {
> > +             new_gain = 0x00;
> > +             gain_idx = 1;
> > +     } else if (val == 2 && val2 == 0) {
> > +             new_gain = 0x800;
> > +             gain_idx = 0;
> > +     } else {
> > +             return -EINVAL;
> > +     }
> > +
> > +     ret = regmap_update_bits(data->regmap, VEML6030_REG_ALS_CONF,
> > +                                     VEML6030_ALS_GAIN, new_gain);
> > +     if (ret) {
> > +             dev_err(&data->client->dev,
> > +                             "can't set als gain %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     /*
> > +      * Cache currently set gain & update resolution. For every
> > +      * increase in the gain to next level, resolution is halved
> > +      * and vice-versa.
> > +      */
> > +     if (data->cur_gain < gain_idx)
> > +             data->cur_resolution <<= gain_idx - data->cur_gain;
> > +     else if (data->cur_gain > gain_idx)
> > +             data->cur_resolution >>= data->cur_gain - gain_idx;
> > +
> > +     data->cur_gain = gain_idx;
> > +
> > +     return ret;
> > +}
> > +
> > +static int veml6030_get_als_gain(struct iio_dev *indio_dev,
> > +                                             int *val, int *val2)
> > +{
> > +     int ret, reg;
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     ret = regmap_read(data->regmap, VEML6030_REG_ALS_CONF, &reg);
> > +     if (ret) {
> > +             dev_err(&data->client->dev,
> > +                             "can't als configuration register %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     switch ((reg >> 11) & 0x03) {
> > +     case 0:
> > +             *val = 1;
> > +             *val2 = 0;
> > +             break;
> > +     case 1:
> > +             *val = 2;
> > +             *val2 = 0;
> > +             break;
> > +     case 2:
> > +             *val = 0;
> > +             *val2 = 125000;
> > +             break;
> > +     case 3:
> > +             *val = 0;
> > +             *val2 = 250000;
> > +             break;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +
> > +     return IIO_VAL_INT_PLUS_MICRO;
> > +}
> > +
> > +static int veml6030_read_thresh(struct iio_dev *indio_dev,
> > +                                             int *val, int *val2, int dir)
> > +{
> > +     int ret, reg;
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     if (dir == IIO_EV_DIR_RISING)
> > +             ret = regmap_read(data->regmap, VEML6030_REG_ALS_WH, &reg);
> > +     else
> > +             ret = regmap_read(data->regmap, VEML6030_REG_ALS_WL, &reg);
> > +     if (ret) {
> > +             dev_err(&data->client->dev,
> > +                             "can't read als threshold value %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     *val = reg & 0xffff;
> > +     *val2 = 0;
> > +     return IIO_VAL_INT;
> > +}
> > +
> > +static int veml6030_write_thresh(struct iio_dev *indio_dev,
> > +                                             int val, int val2, int dir)
> > +{
> > +     int ret;
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     if (val > 0xFFFF || val < 0 || val2)
> > +             return -EINVAL;
> > +
> > +     if (dir == IIO_EV_DIR_RISING) {
> > +             ret = regmap_write(data->regmap, VEML6030_REG_ALS_WH, val);
> > +             if (ret)
> > +                     dev_err(&data->client->dev,
> > +                                     "can't set high threshold %d\n", ret);
> > +     } else {
> > +             ret = regmap_write(data->regmap, VEML6030_REG_ALS_WL, val);
> > +             if (ret)
> > +                     dev_err(&data->client->dev,
> > +                                     "can't set low threshold %d\n", ret);
> > +     }
> > +
> > +     return ret;
> > +}
> > +
> > +static int veml6030_get_intgrn_tm(struct iio_dev *indio_dev,
> > +                                             int *val, int *val2)
> > +{
> > +     int ret, reg;
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     ret = regmap_read(data->regmap, VEML6030_REG_ALS_CONF, &reg);
> > +     if (ret) {
> > +             dev_err(&data->client->dev,
> > +                             "can't als configuration register %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     switch ((reg >> 6) & 0xF) {
> > +     case 0:
> > +             *val2 = 100000;
> > +             break;
> > +     case 1:
> > +             *val2 = 200000;
> > +             break;
> > +     case 2:
> > +             *val2 = 400000;
> > +             break;
> > +     case 3:
> > +             *val2 = 800000;
> > +             break;
> > +     case 8:
> > +             *val2 = 50000;
> > +             break;
> > +     case 12:
> > +             *val2 = 25000;
> > +             break;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +
> > +     *val = 0;
> > +     return IIO_VAL_INT_PLUS_MICRO;
> > +}
> > +
> > +static int veml6030_set_intgrn_tm(struct iio_dev *indio_dev,
> > +                                             int val, int val2)
> > +{
> > +     int ret, new_int_time, int_idx;
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     if (val)
> > +             return -EINVAL;
> > +
> > +     switch (val2) {
> > +     case 25000:
> > +             new_int_time = 0x300;
> > +             int_idx = 5;
> > +             break;
> > +     case 50000:
> > +             new_int_time = 0x200;
> > +             int_idx = 4;
> > +             break;
> > +     case 100000:
> > +             new_int_time = 0x00;
> > +             int_idx = 3;
> > +             break;
> > +     case 200000:
> > +             new_int_time = 0x40;
> > +             int_idx = 2;
> > +             break;
> > +     case 400000:
> > +             new_int_time = 0x80;
> > +             int_idx = 1;
> > +             break;
> > +     case 800000:
> > +             new_int_time = 0xC0;
> > +             int_idx = 0;
> > +             break;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +
> > +     ret = regmap_update_bits(data->regmap, VEML6030_REG_ALS_CONF,
> > +                                     VEML6030_ALS_IT, new_int_time);
> > +     if (ret) {
> > +             dev_err(&data->client->dev,
> > +                             "can't update als integration time %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     /*
> > +      * Cache current integration time and update resolution. For every
> > +      * increase in integration time to next level, resolution is halved
> > +      * and vice-versa.
> > +      */
> > +     if (data->cur_integration_time < int_idx)
> > +             data->cur_resolution <<= int_idx - data->cur_integration_time;
> > +     else if (data->cur_integration_time > int_idx)
> > +             data->cur_resolution >>= data->cur_integration_time - int_idx;
> > +
> > +     data->cur_integration_time = int_idx;
> > +
> > +     return ret;
> > +}
> > +
> > +/*
> > + * Provide both raw as well as light reading in lux.
> > + * light (in lux) = resolution * raw reading
> > + */
> > +static int veml6030_read_raw(struct iio_dev *indio_dev,
> > +                         struct iio_chan_spec const *chan, int *val,
> > +                         int *val2, long mask)
> > +{
> > +     int ret, reg;
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +     struct regmap *regmap = data->regmap;
> > +     struct device *dev = &data->client->dev;
> > +
> > +     switch (mask) {
> > +     case IIO_CHAN_INFO_RAW:
> > +     case IIO_CHAN_INFO_PROCESSED:
> > +             switch (chan->type) {
> > +             case IIO_LIGHT:
> > +                     ret = regmap_read(regmap, VEML6030_REG_ALS_DATA, &reg);
> > +                     if (ret < 0) {
> > +                             dev_err(dev, "can't read als data %d\n", ret);
> > +                             return ret;
> > +                     }
> > +                     if (mask == IIO_CHAN_INFO_PROCESSED) {
> > +                             *val = (reg * data->cur_resolution) / 10000;
> > +                             *val2 = (reg * data->cur_resolution) % 10000;
> > +                             return IIO_VAL_INT_PLUS_MICRO;
> > +                     }
> > +                     *val = reg;
> > +                     *val2 = 0;
> > +                     return IIO_VAL_INT;
> > +             case IIO_INTENSITY:
> > +                     ret = regmap_read(regmap, VEML6030_REG_WH_DATA, &reg);
> > +                     if (ret < 0) {
> > +                             dev_err(dev, "can't read white data %d\n", ret);
> > +                             return ret;
> > +                     }
> > +                     if (mask == IIO_CHAN_INFO_PROCESSED) {
> > +                             *val = (reg * data->cur_resolution) / 10000;
> > +                             *val2 = (reg * data->cur_resolution) % 10000;
> > +                             return IIO_VAL_INT_PLUS_MICRO;
> > +                     }
> > +                     *val = reg;
> > +                     *val2 = 0;
>
> No need to set val2 if returning IIO_VAL_INT, it's not read.
>
> > +                     return IIO_VAL_INT;
> > +             default:
> > +                     return -EINVAL;
> > +             }
> > +     case IIO_CHAN_INFO_INT_TIME:
> > +             if (chan->type == IIO_LIGHT)
> > +                     return veml6030_get_intgrn_tm(indio_dev, val, val2);
> > +             return -EINVAL;
> > +     case IIO_CHAN_INFO_SCALE:
> > +             if (chan->type == IIO_LIGHT)
> > +                     return veml6030_get_als_gain(indio_dev, val, val2);
> > +             return -EINVAL;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +}
> > +
> > +static int veml6030_write_raw(struct iio_dev *indio_dev,
> > +                             struct iio_chan_spec const *chan,
> > +                             int val, int val2, long mask)
> > +{
> > +     switch (mask) {
> > +     case IIO_CHAN_INFO_INT_TIME:
> > +             switch (chan->type) {
> > +             case IIO_LIGHT:
> > +                     return veml6030_set_intgrn_tm(indio_dev, val, val2);
> > +             default:
> > +                     return -EINVAL;
> > +             }
> > +     case IIO_CHAN_INFO_SCALE:
> > +             switch (chan->type) {
> > +             case IIO_LIGHT:
> > +                     return veml6030_set_als_gain(indio_dev, val, val2);
> > +             default:
> > +                     return -EINVAL;
> > +             }
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +}
> > +
> > +static int veml6030_read_event_val(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)
> > +{
> > +     switch (info) {
> > +     case IIO_EV_INFO_VALUE:
> > +             switch (dir) {
> > +             case IIO_EV_DIR_RISING:
> > +             case IIO_EV_DIR_FALLING:
> > +                     return veml6030_read_thresh(indio_dev, val, val2, dir);
> > +             default:
> > +                     return -EINVAL;
> > +             }
> > +             break;
> > +     case IIO_EV_INFO_PERIOD:
> > +             return veml6030_read_persistence(indio_dev, val, val2);
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +}
> > +
> > +static int veml6030_write_event_val(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)
> > +{
> > +     switch (info) {
> > +     case IIO_EV_INFO_VALUE:
> > +             return veml6030_write_thresh(indio_dev, val, val2, dir);
> > +     case IIO_EV_INFO_PERIOD:
> > +             return veml6030_write_persistence(indio_dev, val, val2);
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +
> You can't get here, so loose this final return.
> > +     return -EINVAL;
> > +}
> > +
> > +static int veml6030_read_interrupt_config(struct iio_dev *indio_dev,
> > +             const struct iio_chan_spec *chan, enum iio_event_type type,
> > +             enum iio_event_direction dir)
> > +{
> > +     int ret, reg;
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     ret = regmap_read(data->regmap, VEML6030_REG_ALS_CONF, &reg);
> > +     if (ret) {
> > +             dev_err(&data->client->dev,
> > +                             "can't read als conf register %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     if (reg & VEML6030_ALS_INT_EN)
> > +             return 1;
> > +     else
> > +             return 0;
> > +}
> > +
> > +/*
> > + * Sensor should not be measuring light when interrupt is configured.
> > + * Therefore correct sequence to configure interrupt functionality is:
> > + * shut down -> enable/disable interrupt -> power on
> > + *
> > + * state = 1 enables interrupt, state = 0 disables interrupt
> > + */
> > +static int veml6030_write_interrupt_config(struct iio_dev *indio_dev,
> > +             const struct iio_chan_spec *chan, enum iio_event_type type,
> > +             enum iio_event_direction dir, int state)
> > +{
> > +     int ret;
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     if (state < 0 || state > 1)
> > +             return -EINVAL;
> > +
> > +     ret = veml6030_als_shut_down(data);
> > +     if (ret < 0) {
> > +             dev_err(&data->client->dev,
> > +                     "can't disable als to configure interrupt %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     /* enable interrupt + power on */
> > +     ret = regmap_update_bits(data->regmap, VEML6030_REG_ALS_CONF,
> > +                     VEML6030_ALS_INT_EN | VEML6030_ALS_SD, state << 1);
> > +     if (ret)
> > +             dev_err(&data->client->dev,
> > +                     "can't enable interrupt & poweron als %d\n", ret);
> > +
> > +     return ret;
> > +}
> > +
> > +static const struct iio_info veml6030_info = {
> > +     .read_raw  = veml6030_read_raw,
> > +     .write_raw = veml6030_write_raw,
> > +     .read_event_value = veml6030_read_event_val,
> > +     .write_event_value      = veml6030_write_event_val,
> > +     .read_event_config = veml6030_read_interrupt_config,
> > +     .write_event_config     = veml6030_write_interrupt_config,
> > +     .attrs = &veml6030_attr_group,
> > +     .event_attrs = &veml6030_event_attr_group,
> > +};
> > +
> > +static const struct iio_info veml6030_info_no_irq = {
> > +     .read_raw  = veml6030_read_raw,
> > +     .write_raw = veml6030_write_raw,
> > +     .attrs = &veml6030_attr_group,
> > +};
> > +
> > +static irqreturn_t veml6030_event_handler(int irq, void *private)
> > +{
> > +     int ret, reg, evtdir;
> > +     struct iio_dev *indio_dev = private;
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     ret = regmap_read(data->regmap, VEML6030_REG_ALS_INT, &reg);
> > +     if (ret) {
> > +             dev_err(&data->client->dev,
> > +                             "can't read als interrupt register %d\n", ret);
> > +             return IRQ_HANDLED;
> > +     }
> > +
> > +     /* Spurious interrupt handling */
> > +     if (!(reg & (VEML6030_INT_TH_HIGH | VEML6030_INT_TH_LOW)))
> > +             return IRQ_NONE;
> > +
> > +     if (reg & VEML6030_INT_TH_HIGH)
> > +             evtdir = IIO_EV_DIR_RISING;
> > +     else
> > +             evtdir = IIO_EV_DIR_FALLING;
> > +
> > +     iio_push_event(indio_dev, IIO_UNMOD_EVENT_CODE(IIO_INTENSITY,
> > +                                     0, IIO_EV_TYPE_THRESH, evtdir),
> > +                                     iio_get_time_ns(indio_dev));
> > +
> > +     return IRQ_HANDLED;
> > +}
> > +
> > +/*
> > + * Set ALS gain to 1/8, integration time to 100 ms, PSM to mode 2,
> > + * persistence to 1 x integration time and the threshold
> > + * interrupt disabled by default. First shutdown the sensor,
> > + * update registers and then power on the sensor.
> > + */
> > +static int veml6030_hw_init(struct iio_dev *indio_dev)
> > +{
> > +     int ret, val;
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +     struct i2c_client *client = data->client;
> > +
> > +     ret = veml6030_als_shut_down(data);
> > +     if (ret) {
> > +             dev_err(&client->dev, "can't shutdown als %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     ret = regmap_write(data->regmap, VEML6030_REG_ALS_CONF, 0x1001);
> > +     if (ret) {
> > +             dev_err(&client->dev, "can't setup als configs %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     ret = regmap_update_bits(data->regmap, VEML6030_REG_ALS_PSM,
> > +                              VEML6030_PSM | VEML6030_PSM_EN, 0x03);
> > +     if (ret) {
> > +             dev_err(&client->dev, "can't setup default PSM %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     ret = regmap_write(data->regmap, VEML6030_REG_ALS_WH, 0xFFFF);
> > +     if (ret) {
> > +             dev_err(&client->dev, "can't setup high threshold %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     ret = regmap_write(data->regmap, VEML6030_REG_ALS_WL, 0x0000);
> > +     if (ret) {
> > +             dev_err(&client->dev, "can't setup low threshold %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     ret = veml6030_als_pwr_on(data);
> > +     if (ret) {
> > +             dev_err(&client->dev, "can't poweron als %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     /* Wait 4 ms to let processor & oscillator start correctly */
> > +     usleep_range(3990, 4000);
>
> I you need to sleep 4msecs then the smallest value needs to be 4msecs.
>
> > +
> > +     /* Clear stale interrupt status bits if any during start */
> > +     ret = regmap_read(data->regmap, VEML6030_REG_ALS_INT, &val);
> > +     if (ret < 0) {
> > +             dev_err(&client->dev,
> > +                     "can't clear als interrupt status %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     /* Cache currently active measurement parameters */
> > +     data->cur_gain = 3;
> > +     data->cur_resolution = 4608;
> > +     data->cur_integration_time = 3;
> > +
> > +     return ret;
> > +}
> > +
> > +static int veml6030_probe(struct i2c_client *client,
> > +                       const struct i2c_device_id *id)
> > +{
> > +     int ret;
> > +     struct veml6030_data *data;
> > +     struct iio_dev *indio_dev;
> > +     struct regmap *regmap;
> > +
> > +     if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> > +             dev_err(&client->dev, "i2c adapter doesn't support plain i2c\n");
> > +             return -EOPNOTSUPP;
> > +     }
> > +
> > +     regmap = devm_regmap_init_i2c(client, &veml6030_regmap_config);
> > +     if (IS_ERR(regmap)) {
> > +             dev_err(&client->dev, "can't setup regmap\n");
> > +             return PTR_ERR(regmap);
> > +     }
> > +
> > +     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;
> > +     data->regmap = regmap;
> > +
> > +     indio_dev->dev.parent = &client->dev;
> > +     indio_dev->name = "veml6030";
> > +     indio_dev->channels = veml6030_channels;
> > +     indio_dev->num_channels = ARRAY_SIZE(veml6030_channels);
> > +     indio_dev->modes = INDIO_DIRECT_MODE;
> > +
> > +     if (client->irq) {
> > +             ret = devm_request_threaded_irq(&client->dev, client->irq,
> > +                                             NULL, veml6030_event_handler,
> > +                                             IRQF_TRIGGER_LOW | IRQF_ONESHOT,
> > +                                             "veml6030", indio_dev);
> > +             if (ret < 0) {
> > +                     dev_err(&client->dev,
> > +                                     "irq %d request failed\n", client->irq);
> > +                     return ret;
> > +             }
> > +             indio_dev->info = &veml6030_info;
> > +     } else {
> > +             indio_dev->info = &veml6030_info_no_irq;
> > +     }
> > +
> > +     ret = devm_add_action_or_reset(&client->dev,
> > +                                     veml6030_als_shut_down_action, data);
>
> What is this reversing?  It should be immediately after whatever that is, thus
> ensuring we only undo whatever we need to on failure and the ordering is correct
> for remove.  I am guessing it should be after hw_init.
>
This just disables active measurements (this is the only thing we need
to do when failure happens).

Suppose hw initialisation succeeds but call to
devm_add_action_or_reset() fails. In this case sensor will be left
turned on as veml6030_als_shut_down_action() will never be executed.
Therefore I kept it before veml6030_hw_init().
Does this sounds correct to you ?

> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     ret = veml6030_hw_init(indio_dev);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     return devm_iio_device_register(&client->dev, indio_dev);
> > +}
> > +
> > +static int __maybe_unused veml6030_runtime_suspend(struct device *dev)
> > +{
> > +     int ret;
> > +     struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     ret = veml6030_als_shut_down(data);
> > +     if (ret < 0)
> > +             dev_err(&data->client->dev, "can't suspend als %d\n", ret);
> > +
> > +     return ret;
> > +}
> > +
> > +static int __maybe_unused veml6030_runtime_resume(struct device *dev)
> > +{
> > +     int ret;
> > +     struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> > +     struct veml6030_data *data = iio_priv(indio_dev);
> > +
> > +     ret = veml6030_als_pwr_on(data);
> > +     if (ret < 0)
> > +             dev_err(&data->client->dev, "can't resume als %d\n", ret);
> > +
> > +     return ret;
> > +}
> > +
> > +static const struct dev_pm_ops veml6030_pm_ops = {
> > +     SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> > +                             pm_runtime_force_resume)
> > +     SET_RUNTIME_PM_OPS(veml6030_runtime_suspend,
> > +                             veml6030_runtime_resume, NULL)
> > +};
> > +
> > +static const struct of_device_id veml6030_of_match[] = {
> > +     { .compatible = "vishay,veml6030" },
> > +     { }
> > +};
> > +MODULE_DEVICE_TABLE(of, veml6030_of_match);
> > +
> > +static const struct i2c_device_id veml6030_id[] = {
> > +     { "veml6030", 0 },
> > +     { }
> > +};
> > +MODULE_DEVICE_TABLE(i2c, veml6030_id);
> > +
> > +static struct i2c_driver veml6030_driver = {
> > +     .driver = {
> > +             .name = "veml6030",
> > +             .of_match_table = veml6030_of_match,
> > +             .pm = &veml6030_pm_ops,
> > +     },
> > +     .probe = veml6030_probe,
> > +     .id_table = veml6030_id,
> > +};
> > +module_i2c_driver(veml6030_driver);
> > +
> > +MODULE_AUTHOR("Rishi Gupta <gupt21@gmail.com>");
> > +MODULE_DESCRIPTION("VEML6030 Ambient Light Sensor");
> > +MODULE_LICENSE("GPL v2");
>