Re: [PATCH V1 1/1] iio: Added Capella cm3232 ambient light sensor driver.

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On Thu, Jan 1, 2015 at 2:10 AM, Kevin Tsai <ktsai@xxxxxxxxxxxxxxxx> wrote:
> CM3232 is an advanced ambient light sensor with I2C protocol interface.
> The I2C slave address is internally hardwired as 0x10 (7-bit).  Writing
> to configure register is byte mode, but reading ALS register requests to
> use word mode for 16-bit resolution.

This looks good to me.  Few comments inline.

>
> Signed-off-by: Kevin Tsai <ktsai@xxxxxxxxxxxxxxxx>
> ---
>  .../devicetree/bindings/i2c/trivial-devices.txt    |   1 +
>  MAINTAINERS                                        |   6 +
>  drivers/iio/light/Kconfig                          |  11 +
>  drivers/iio/light/Makefile                         |   1 +
>  drivers/iio/light/cm3232.c                         | 403 +++++++++++++++++++++
>  5 files changed, 422 insertions(+)
>  create mode 100644 drivers/iio/light/cm3232.c
>
> diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> index 9f4e382..572a7c4 100644
> --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> @@ -34,6 +34,7 @@ atmel,24c512          i2c serial eeprom  (24cxx)
>  atmel,24c1024          i2c serial eeprom  (24cxx)
>  atmel,at97sc3204t      i2c trusted platform module (TPM)
>  capella,cm32181                CM32181: Ambient Light Sensor
> +capella,cm3232         CM3232: Ambient Light Sensor
>  catalyst,24c32         i2c serial eeprom
>  cirrus,cs42l51         Cirrus Logic CS42L51 audio codec
>  dallas,ds1307          64 x 8, Serial, I2C Real-Time Clock
> diff --git a/MAINTAINERS b/MAINTAINERS
> index ddb9ac8..06a613a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2378,6 +2378,12 @@ F:       security/capability.c
>  F:     security/commoncap.c
>  F:     kernel/capability.c
>
> +CAPELLA MICROSYSTEMS LIGHT SENSOR DRIVER
> +M:     Kevin Tsai <ktsai@xxxxxxxxxxxxxxxx>
> +S:     Maintained
> +F:     drivers/iio/light/cm*
> +F:     Documentation/devicetree/bindings/i2c/trivial-devices.txt
> +
>  CC2520 IEEE-802.15.4 RADIO DRIVER
>  M:     Varka Bhadram <varkabhadram@xxxxxxxxx>
>  L:     linux-wpan@xxxxxxxxxxxxxxx
> diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
> index 5bea821..d2318e2 100644
> --- a/drivers/iio/light/Kconfig
> +++ b/drivers/iio/light/Kconfig
> @@ -48,6 +48,17 @@ config CM32181
>          To compile this driver as a module, choose M here:
>          the module will be called cm32181.
>
> +config CM3232
> +       depends on I2C
> +       tristate "CM3232 driver"

Better name this: "CM3232 ambient light sensor".

> +       help
> +        Say Y here if you use cm3232.
> +        This option enables ambient light sensor using
> +        Capella Microsystems cm3232 device driver.
> +
> +        To compile this driver as a module, choose M here:
> +        the module will be called cm3232.
> +
>  config CM36651
>         depends on I2C
>         tristate "CM36651 driver"
> diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
> index 47877a3..f2c8d55 100644
> --- a/drivers/iio/light/Makefile
> +++ b/drivers/iio/light/Makefile
> @@ -7,6 +7,7 @@ obj-$(CONFIG_ADJD_S311)         += adjd_s311.o
>  obj-$(CONFIG_AL3320A)          += al3320a.o
>  obj-$(CONFIG_APDS9300)         += apds9300.o
>  obj-$(CONFIG_CM32181)          += cm32181.o
> +obj-$(CONFIG_CM3232)           += cm3232.o
>  obj-$(CONFIG_CM36651)          += cm36651.o
>  obj-$(CONFIG_GP2AP020A00F)     += gp2ap020a00f.o
>  obj-$(CONFIG_HID_SENSOR_ALS)   += hid-sensor-als.o
> diff --git a/drivers/iio/light/cm3232.c b/drivers/iio/light/cm3232.c
> new file mode 100644
> index 0000000..fd98eeb
> --- /dev/null
> +++ b/drivers/iio/light/cm3232.c
> @@ -0,0 +1,403 @@
> +/*
> + * Copyright (C) 2014 Capella Microsystems Inc.
> + * Author: Kevin Tsai <ktsai@xxxxxxxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2, as published
> + * by the Free Software Foundation.
> + *

Usually, here is the place to mention the I2C slave address.

> + */
> +
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/mutex.h>
> +#include <linux/module.h>
> +#include <linux/interrupt.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/events.h>
> +#include <linux/init.h>
> +
> +/* Registers Address */
> +#define CM3232_REG_ADDR_CMD            0x00
> +#define CM3232_REG_ADDR_ALS            0x50
> +#define CM3232_REG_ADDR_ID             0x53
> +
> +/* CMD register */
> +#define CM3232_CMD_ALS_DISABLE         BIT(0)
> +#define        CM3232_CMD_ALS_HS               BIT(1)
> +
> +#define CM3232_CMD_ALS_IT_SHIFT         2
> +#define CM3232_CMD_ALS_IT_MASK          (0x07 << CM3232_CMD_ALS_IT_SHIFT)
> +#define CM3232_CMD_ALS_IT_DEFAULT       (0x01 << CM3232_CMD_ALS_IT_SHIFT)
> +
> +#define        CM3232_CMD_ALS_RESET            BIT(6)
> +
> +#define CM3232_CMD_DEFAULT             CM3232_CMD_ALS_IT_DEFAULT
> +
> +#define CM3232_CALIBSCALE_DEFAULT      100000
> +#define CM3232_CALIBSCALE_RESOLUTION   100000
> +#define CM3232_MLUX_PER_LUX            1000
> +
> +#define CM3232_MLUX_PER_BIT_DEFAULT    64
> +#define CM3232_MLUX_PER_BIT_BASE_IT    100000
> +static const int CM3232_als_it_bits[] = { 0, 1, 2, 3, 4, 5};
> +static const int CM3232_als_it_values[] = {
> +                       100000, 200000, 400000, 800000, 1600000, 3200000};
> +
> +struct cm3232_als_info {
> +       u32 id;
> +       int calibscale;
> +       int mlux_per_bit;
> +       int mlux_per_bit_base_it;
> +       const int *als_it_bits;
> +       const int *als_it_values;
> +       const int num_als_it;
> +       int als_raw;
> +};
> +
> +static struct cm3232_als_info cm3232_als_info_default = {
> +       .id = 3232,
> +       .calibscale = CM3232_CALIBSCALE_DEFAULT,
> +       .mlux_per_bit = CM3232_MLUX_PER_BIT_DEFAULT,
> +       .mlux_per_bit_base_it = CM3232_MLUX_PER_BIT_BASE_IT,
> +       .als_it_bits = CM3232_als_it_bits,
> +       .als_it_values = CM3232_als_it_values,
> +       .num_als_it = ARRAY_SIZE(CM3232_als_it_bits),
> +};
> +
> +struct cm3232_chip {
> +       struct i2c_client *client;
> +       struct mutex lock;
> +       struct cm3232_als_info *als_info;
> +       u8 regs_cmd;
> +};
> +
> +static int cm3232_get_lux(struct cm3232_chip *chip);
> +static int cm3232_read_als_it(struct cm3232_chip *chip, int *val2);
> +
> +/**
> + * cm3232_reg_init() - Initialize CM3232 registers
> + * @chip:      pointer of struct cm3232.
> + *
> + * Initialize CM3232 ambient light sensor register to default values.
> + *
> +  Return: 0 for success; otherwise for error code.
> + */
> +static int cm3232_reg_init(struct cm3232_chip *chip)
> +{
> +       struct i2c_client *client = chip->client;
> +       struct cm3232_als_info *als_info;
> +       s32 ret;
> +
> +       /* Identify device */
> +       ret = i2c_smbus_read_word_data(client, CM3232_REG_ADDR_ID);
> +       if (ret < 0)
> +               return ret;
> +       if ((ret & 0xFF) != 0x32)
> +               return -ENODEV;
> +
> +       /* Disable and reset device */
> +       chip->regs_cmd = CM3232_CMD_ALS_DISABLE | CM3232_CMD_ALS_RESET;
> +       ret = i2c_smbus_write_byte_data(client, CM3232_REG_ADDR_CMD,
> +                               chip->regs_cmd);
> +       if (ret < 0)
> +               return ret;
> +
> +       /* Initialization */
> +       als_info = chip->als_info = &cm3232_als_info_default;
> +       chip->regs_cmd = CM3232_CMD_DEFAULT;
> +
> +       /* Configure register */
> +       ret = i2c_smbus_write_byte_data(client, CM3232_REG_ADDR_CMD,
> +                               chip->regs_cmd);

You could directly return i2c_smbus_write_byte_data(..).

> +       if (ret < 0)
> +               return ret;
> +
> +       return 0;
> +}
> +
> +/**
> + *  cm3232_read_als_it() - Get sensor integration time (ms)
> + *  @chip:     pointer of struct cm3232
> + *  @val2:     pointer of int to load the als_it value.
> + *
> + *  Report the current integration time in milliseconds.
> + *
> + *  Return: IIO_VAL_INT_PLUS_MICRO for success, otherwise -EINVAL.
> + */
> +static int cm3232_read_als_it(struct cm3232_chip *chip, int *val2)

Wouldn't make more sense to also add val here?

> +{
> +       struct cm3232_als_info *als_info = chip->als_info;
> +       u16 als_it;
> +       int i;
> +
> +       als_it = chip->regs_cmd;
> +       als_it &= CM3232_CMD_ALS_IT_MASK;
> +       als_it >>= CM3232_CMD_ALS_IT_SHIFT;
> +       for (i = 0; i < als_info->num_als_it; i++) {
> +               if (als_it == als_info->als_it_bits[i]) {
.. then make, *val = 0.

> +                       *val2 = als_info->als_it_values[i];
> +                       return IIO_VAL_INT_PLUS_MICRO;
> +               }
> +       }
> +
> +       return -EINVAL;
> +}
> +
> +/**
> + * cm3232_write_als_it() - Write sensor integration time
> + * @chip:      pointer of struct cm3232.
> + * @val:       integration time in milliseconds.
> + *
> + * Convert integration time (ms) to sensor value.
> + *
> + * Return: i2c_smbus_write_word_data command return value.
> + */
> +static int cm3232_write_als_it(struct cm3232_chip *chip, int val)
> +{
> +       struct i2c_client *client = chip->client;
> +       struct cm3232_als_info *als_info = chip->als_info;
> +       u16 als_it;
> +       int ret, i;
> +
> +       for (i = 0; i < als_info->num_als_it; i++)
> +               if (val <= als_info->als_it_values[i])
> +                       break;
> +       if (i >= als_info->num_als_it)
> +               i = als_info->num_als_it - 1;
> +
> +       als_it = als_info->als_it_bits[i];
> +       als_it <<= CM3232_CMD_ALS_IT_SHIFT;
> +
> +       mutex_lock(&chip->lock);
> +       chip->regs_cmd &= ~CM3232_CMD_ALS_IT_MASK;
> +       chip->regs_cmd |= als_it;
> +       ret = i2c_smbus_write_byte_data(client, CM3232_REG_ADDR_CMD,
> +                       chip->regs_cmd);
> +       mutex_unlock(&chip->lock);
> +
> +       return ret;
> +}
> +
> +/**
> + * cm3232_get_lux() - report current lux value
> + * @chip:      pointer of struct cm3232.
> + *
> + * Convert sensor raw data to lux.  It depends on integration
> + * time and calibscale variable.
> + *
> + * Return: Positive value is lux, otherwise is error code.
> + */
> +static int cm3232_get_lux(struct cm3232_chip *chip)
> +{
> +       struct i2c_client *client = chip->client;
> +       struct cm3232_als_info *als_info = chip->als_info;
> +       int ret;
> +       int als_it;
> +       u64 tmp;
> +
> +       /* Calculate mlux per bit based on als_it */
> +       ret = cm3232_read_als_it(chip, &als_it);
> +       if (ret < 0)
> +               return -EINVAL;
> +       tmp = (__force u64)als_info->mlux_per_bit;
> +       tmp *= als_info->mlux_per_bit_base_it;
> +       tmp = div_u64 (tmp, als_it);
> +
> +       /* Get als_raw */
> +       als_info->als_raw = i2c_smbus_read_word_data(
> +                               client,
> +                               CM3232_REG_ADDR_ALS);
> +       if (als_info->als_raw < 0)
> +               return als_info->als_raw;
> +
> +       tmp *= als_info->als_raw;
> +       tmp *= als_info->calibscale;
> +       tmp = div_u64(tmp, CM3232_CALIBSCALE_RESOLUTION);
> +       tmp = div_u64(tmp, CM3232_MLUX_PER_LUX);
> +
> +       if (tmp > 0xFFFF)
> +               tmp = 0xFFFF;
> +
> +       return (int)tmp;
> +}
> +
> +static int cm3232_read_raw(struct iio_dev *indio_dev,
> +                       struct iio_chan_spec const *chan,
> +                       int *val, int *val2, long mask)
> +{
> +       struct cm3232_chip *chip = iio_priv(indio_dev);
> +       struct cm3232_als_info *als_info = chip->als_info;
> +       int ret;
> +
> +       switch (mask) {
> +       case IIO_CHAN_INFO_PROCESSED:
> +               ret = cm3232_get_lux(chip);
> +               if (ret < 0)
> +                       return ret;
> +               *val = ret;
> +               return IIO_VAL_INT;
> +       case IIO_CHAN_INFO_CALIBSCALE:
> +               *val = als_info->calibscale;
> +               return IIO_VAL_INT;
> +       case IIO_CHAN_INFO_INT_TIME:
> +               *val = 0;
> +               ret = cm3232_read_als_it(chip, val2);
> +               return ret;
Here you could just return cm3232_read_als_it(...)
> +       }
> +
> +       return -EINVAL;
> +}
> +
> +static int cm3232_write_raw(struct iio_dev *indio_dev,
> +                       struct iio_chan_spec const *chan,
> +                       int val, int val2, long mask)
> +{
> +       struct cm3232_chip *chip = iio_priv(indio_dev);
> +       struct cm3232_als_info *als_info = chip->als_info;
> +       long ms;
> +
> +       switch (mask) {
> +       case IIO_CHAN_INFO_CALIBSCALE:
> +               als_info->calibscale = val;
> +               return val;
> +       case IIO_CHAN_INFO_INT_TIME:
> +               ms = val * 1000000 + val2;
> +               return cm3232_write_als_it(chip, (int)ms);
> +       }
> +
> +       return -EINVAL;
> +}
> +
> +/**
> + * cm3232_get_it_available() - Get available ALS IT value
> + * @dev:       pointer of struct device.
> + * @attr:      pointer of struct device_attribute.
> + * @buf:       pointer of return string buffer.
> + *
> + * Display the available integration time in milliseconds.
> + *
> + * Return: string length.
> + */
> +static ssize_t cm3232_get_it_available(struct device *dev,
> +                       struct device_attribute *attr, char *buf)
> +{
> +       struct cm3232_chip *chip = iio_priv(dev_to_iio_dev(dev));
> +       struct cm3232_als_info *als_info = chip->als_info;
> +       int i, len;
> +
> +       for (i = 0, len = 0; i < als_info->num_als_it; i++)
> +               len += scnprintf(buf + len, PAGE_SIZE - len, "%u.%06u ",
> +                       als_info->als_it_values[i]/1000000,
> +                       als_info->als_it_values[i]%1000000);
> +       return len + scnprintf(buf + len, PAGE_SIZE - len, "\n");
> +}
> +
> +static const struct iio_chan_spec cm3232_channels[] = {
> +       {
> +               .type = IIO_LIGHT,
> +               .info_mask_separate =
> +                       BIT(IIO_CHAN_INFO_PROCESSED) |
> +                       BIT(IIO_CHAN_INFO_CALIBSCALE) |
> +                       BIT(IIO_CHAN_INFO_INT_TIME),
> +       }
> +};
> +
> +static IIO_DEVICE_ATTR(in_illuminance_integration_time_available,
> +                       S_IRUGO, cm3232_get_it_available, NULL, 0);
> +
> +static struct attribute *cm3232_attributes[] = {
> +       &iio_dev_attr_in_illuminance_integration_time_available.dev_attr.attr,
> +       NULL,
> +};
> +
> +static const struct attribute_group cm3232_attribute_group = {
> +       .attrs = cm3232_attributes
> +};
> +
> +static const struct iio_info cm3232_info = {
> +       .driver_module          = THIS_MODULE,
> +       .read_raw               = &cm3232_read_raw,
> +       .write_raw              = &cm3232_write_raw,
> +       .attrs                  = &cm3232_attribute_group,
> +};
> +
> +static int cm3232_probe(struct i2c_client *client,
> +                       const struct i2c_device_id *id)
> +{
> +       struct cm3232_chip *chip;
> +       struct iio_dev *indio_dev;
> +       int ret;
> +
> +       indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
> +       if (!indio_dev) {
> +               dev_err(&client->dev, "devm_iio_device_alloc failed\n");

There is no need for this error message. devm_iio_device_alloc will print
an error message in case of failure.

> +               return -ENOMEM;
> +       }
> +
> +       chip = iio_priv(indio_dev);
> +       i2c_set_clientdata(client, indio_dev);
> +       chip->client = client;
> +
> +       mutex_init(&chip->lock);
> +       indio_dev->dev.parent = &client->dev;
> +       indio_dev->channels = cm3232_channels;
> +       indio_dev->num_channels = ARRAY_SIZE(cm3232_channels);
> +       indio_dev->info = &cm3232_info;
> +       if (id && id->name)
> +               indio_dev->name = id->name;
> +       else
> +               indio_dev->name = (char *)dev_name(&client->dev);
> +       indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +       ret = cm3232_reg_init(chip);
> +       if (ret) {
> +               dev_err(&client->dev,
> +                       "%s: register init failed\n",
> +                       __func__);
> +               return ret;
> +       }
> +
> +       ret = iio_device_register(indio_dev);
> +       return 0;
Directly return iio_device_register()
> +}
> +
> +static int cm3232_remove(struct i2c_client *client)
> +{
> +       struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +
> +       iio_device_unregister(indio_dev);
> +       return 0;
> +}
> +
> +static const struct i2c_device_id cm3232_id[] = {
> +       { "cm3232", 0},
No need for space before ".

> +       { }
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, cm3232_id);
> +
> +static const struct of_device_id cm3232_of_match[] = {
> +       { .compatible = "capella,cm3232" },
Same here. No need for space before "."

> +       { }
> +};
> +
> +static struct i2c_driver cm3232_driver = {
> +       .driver = {
> +               .name   = "cm3232",
> +               .owner  = THIS_MODULE,
> +               .of_match_table = of_match_ptr(cm3232_of_match),
> +       },
> +       .id_table       = cm3232_id,
> +       .probe          = cm3232_probe,
> +       .remove         = cm3232_remove,
> +};
> +
> +module_i2c_driver(cm3232_driver);
> +
> +MODULE_AUTHOR("Kevin Tsai <ktsai@xxxxxxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("CM3232 ambient light sensor driver");
> +MODULE_LICENSE("GPL");
> --
> 1.8.3.1
>
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