Re: [PATCH V2 1/1] iio: add Capella CM32181 ambient light sensor driver.

["Kevin Tsai" <ktsai@capellamicro.com>]

Hi Jonathan,

Thanks for your review.  I've modifoed it and post the [PATCH V3 1/1]. 
Please review it again.

By the way, I did always use the "scripts/checkpatch.pl" before I submit it. 
It looks like script cannot catch the "i = n-1;" case.

Also, please guide me how to use the staging-next tree.  I will modify it to 
"devm_iio_device_register" API.

Thanks.

Kevin Tsai
12/23/13

----- Original Message ----- 
From: "Jonathan Cameron" <jic23@kernel.org>
To: "Kevin Tsai" <ktsai@capellamicro.com>; "Grant Likely" 
<grant.likely@linaro.org>; "Rob Herring" <rob.herring@calxeda.com>; "Peter 
Meerwald" <pmeerw@pmeerw.net>; "Lars-Peter Clausen" <lars@metafoo.de>; 
"Oleksandr Kravchenko" <o.v.kravchenko@globallogic.com>; "Jacek Anaszewski" 
<j.anaszewski@samsung.com>
Cc: <linux-iio@vger.kernel.org>
Sent: Sunday, December 22, 2013 08:00
Subject: Re: [PATCH V2 1/1] iio: add Capella CM32181 ambient light sensor 
driver.


> On 12/18/13 23:10, Kevin Tsai wrote:
>> Add Capella Microsystem CM32181 Ambient Light Sensor IIO driver.
>> This driver will convert raw data to lux value under open-air
>> condition. Change the calibscale based on the cover material.
>>
>> Signed-off-by: Kevin Tsai <ktsai@capellamicro.com>
> Hi Kevin,
>
> The device tree binding still needs documenting - probably in
> Documentation/devicetree/bindings/i2c/trivial-devices.txt
>
> That binding needs to be sent to devicetree@vger.kernel.org.
> The easiest option is probably going to be to do a v3 of this
> patch with that included and send it to both linux-iio and devicetree
> mailing lists.
>
> There are a few more comments inline.  Mainly little things like putting
> function documentation into kernel-doc style and slight tweaks to code
> ordering / error paths that make things a little bit cleaner.
>
> Probably just a few minutes work to be ready to go.
>
> Jonathan
>> ---
>>  drivers/iio/light/Kconfig   |  11 ++
>>  drivers/iio/light/Makefile  |   1 +
>>  drivers/iio/light/cm32181.c | 354 
>> ++++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 366 insertions(+)
>>  create mode 100644 drivers/iio/light/cm32181.c
>>
>> diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
>> index a022f27..d12b2a0 100644
>> --- a/drivers/iio/light/Kconfig
>> +++ b/drivers/iio/light/Kconfig
>> @@ -27,6 +27,17 @@ config APDS9300
>>  To compile this driver as a module, choose M here: the
>>  module will be called apds9300.
>>
>> +config CM32181
>> + depends on I2C
>> + tristate "CM32181 driver"
>> + help
>> + Say Y here if you use cm32181.
>> + This option enables ambient light sensor using
>> + Capella cm32181 device driver.
>> +
>> + To compile this driver as a module, choose M here:
>> + the module will be called cm32181.
>> +
>>  config CM36651
>>  depends on I2C
>>  tristate "CM36651 driver"
>> diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
>> index daa327f..60e35ac 100644
>> --- a/drivers/iio/light/Makefile
>> +++ b/drivers/iio/light/Makefile
>> @@ -5,6 +5,7 @@
>>  # When adding new entries keep the list in alphabetical order
>>  obj-$(CONFIG_ADJD_S311) += adjd_s311.o
>>  obj-$(CONFIG_APDS9300) += apds9300.o
>> +obj-$(CONFIG_CM32181) += cm32181.o
>>  obj-$(CONFIG_CM36651) += cm36651.o
>>  obj-$(CONFIG_GP2AP020A00F) += gp2ap020a00f.o
>>  obj-$(CONFIG_HID_SENSOR_ALS) += hid-sensor-als.o
>> diff --git a/drivers/iio/light/cm32181.c b/drivers/iio/light/cm32181.c
>> new file mode 100644
>> index 0000000..305789b
>> --- /dev/null
>> +++ b/drivers/iio/light/cm32181.c
>> @@ -0,0 +1,354 @@
>> +/*
>> + * Copyright (C) 2013 Capella Microsystems Inc.
>> + * Author: Kevin Tsai <ktsai@capellamicro.com>
>> + *
>> + * 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.
>> + */
>> +
>> +#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 CM32181_REG_ADDR_CMD 0x00
>> +#define CM32181_REG_ADDR_ALS 0x04
>> +#define CM32181_REG_ADDR_STATUS 0x06
>> +#define CM32181_REG_ADDR_ID 0x07
>> +
>> +/* Number of Configurable Registers */
>> +#define CM32181_CONF_REG_NUM 0x01
>> +
>> +/* CMD register */
>> +#define CM32181_CMD_ALS_ENABLE 0x00
>> +#define CM32181_CMD_ALS_DISABLE 0x01
>> +#define CM32181_CMD_ALS_INT_EN 0x02
>> +
>> +#define CM32181_CMD_ALS_IT_SHIFT 6
>> +#define CM32181_CMD_ALS_IT_MASK (0x0F << CM32181_CMD_ALS_IT_SHIFT)
>> +#define CM32181_CMD_ALS_IT_DEFAULT (0x00 << CM32181_CMD_ALS_IT_SHIFT)
>> +
>> +#define CM32181_CMD_ALS_SM_SHIFT 11
>> +#define CM32181_CMD_ALS_SM_MASK (0x03 << CM32181_CMD_ALS_SM_SHIFT)
>> +#define CM32181_CMD_ALS_SM_DEFAULT (0x01 << CM32181_CMD_ALS_SM_SHIFT)
>> +
>> +#define CM32181_MLUX_PER_BIT 5 /* ALS_SM=01 IT=800ms */
>> +#define CM32181_MLUX_PER_BIT_BASE_IT 800000 /* Based on IT=800ms */
>> +#define CM32181_CALIBSCALE_RESOLUTION 1000
>> +#define MLUX_PER_LUX 1000
>> +
>> +static const u8 cm32181_reg[CM32181_CONF_REG_NUM] = {
>> + CM32181_REG_ADDR_CMD,
>> +};
>> +
>> +static const int als_it_bits[] = {12, 8, 0, 1, 2, 3};
>> +static int als_it_value[] = {25000, 50000, 100000, 200000, 400000, 
>> 800000};
>> +
>> +struct cm32181_chip {
>> + struct i2c_client *client;
>> + struct mutex lock;
>> + u16 conf_regs[CM32181_CONF_REG_NUM];
>> + int calibscale;
>> +};
>> +
>> +static int cm32181_reg_init(struct cm32181_chip *cm32181)
>> +{
>> + struct i2c_client *client = cm32181->client;
>> + int i;
>> + s32 ret;
>> +
>> + cm32181->conf_regs[CM32181_REG_ADDR_CMD] = CM32181_CMD_ALS_ENABLE |
>> + CM32181_CMD_ALS_IT_DEFAULT | CM32181_CMD_ALS_SM_DEFAULT;
>> +
>> + for (i = 0; i < CM32181_CONF_REG_NUM; i++) {
>> + ret = i2c_smbus_write_word_data(client, cm32181_reg[i],
>> + cm32181->conf_regs[i]);
>> + if (ret < 0)
>> + return ret;
>> + }
>> +
>> + cm32181->calibscale = 1000;
>> +
>> + return 0;
>> +}
>> +
>> +/*
>> + *  Get sensor integration time (ms).
>> + *  Return: IIO_VAL_INT for success, otherwise -EINVAL.
>> + */
>> +static int cm32181_read_als_it(struct cm32181_chip *cm32181, int *val)
>> +{
>> + u16 als_it;
>> + int i;
>> +
>> + als_it = cm32181->conf_regs[CM32181_REG_ADDR_CMD];
>> + als_it &= CM32181_CMD_ALS_IT_MASK;
>> + als_it >>= CM32181_CMD_ALS_IT_SHIFT;
>> + for (i = 0; i < sizeof(als_it_bits)/sizeof(als_it_bits[0]); i++) {
>> + if (als_it == als_it_bits[i]) {
>> + *val = als_it_value[i];
>> + if (*val == 0)
>> + return -EINVAL;
>> + return IIO_VAL_INT;
>> + }
>> + }
>> +
>> + return -EINVAL;
>> +}
>> +
>> +/*
>> + * Convert integration time (ms) to sensor value.
>> + * Return: i2c_smbus_write_word_data command return value.
>> + */
>> +static int cm32181_write_als_it(struct cm32181_chip *cm32181, int val)
>> +{
>> + struct i2c_client *client = cm32181->client;
>> + u16 als_it;
>> + int ret, i, n;
>> +
>> + n = sizeof(als_it_value)/sizeof(als_it_value[0]);
>> + for (i = 0; i < n; i++)
>> + if (val <= als_it_value[i])
>> + break;
>> + if (i >= n)
> Should be spaces around that -.
> Please make sure to run scripts/checkpatch.pl which I would have
> expected to catch this and any other similar cases..
>> + i = n-1;
>> +
>> + als_it = als_it_bits[i];
>> + als_it <<= CM32181_CMD_ALS_IT_SHIFT;
>> +
>> + mutex_lock(&cm32181->lock);
>> + cm32181->conf_regs[CM32181_REG_ADDR_CMD] &=
>> + ~CM32181_CMD_ALS_IT_MASK;
>> + cm32181->conf_regs[CM32181_REG_ADDR_CMD] |=
>> + als_it;
>> + ret = i2c_smbus_write_word_data(client, CM32181_REG_ADDR_CMD,
>> + cm32181->conf_regs[CM32181_REG_ADDR_CMD]);
>> + mutex_unlock(&cm32181->lock);
>> +
>> + return ret;
>> +}
>> +
>> +/*
>
> Ideally any documentation will be in kernel-doc style
> Documentation/kernel-doc-nano-HOWTO.txt
>
>> + * Convert sensor data to lux.
>> + * Return: Positive value is lux, otherwise is error code.
>> + */
>> +static int cm32181_get_lux(struct cm32181_chip *cm32181)
>> +{
>> + struct i2c_client *client = cm32181->client;
>> + int ret;
>> + int als_it;
>> + unsigned long lux;
>> +
>> + ret = cm32181_read_als_it(cm32181, &als_it);
>> + if (ret < 0)
>> + return -EINVAL;
>> +
>> + lux = CM32181_MLUX_PER_BIT;
>> + lux *= CM32181_MLUX_PER_BIT_BASE_IT;
>> + lux /= als_it;
>> +
>> + ret = i2c_smbus_read_word_data(client, CM32181_REG_ADDR_ALS);
>> + if (ret < 0)
>> + return ret;
>> +
>> + lux *= ret;
>> + lux *= cm32181->calibscale;
>> + lux /= CM32181_CALIBSCALE_RESOLUTION;
>> + lux /= MLUX_PER_LUX;
>> +
>> + if (lux > 0xFFFF)
>> + lux = 0xFFFF;
>> +
>> + return (int)lux;
>> +}
>> +
>> +static int cm32181_read_raw(struct iio_dev *indio_dev,
>> +     struct iio_chan_spec const *chan,
>> +     int *val, int *val2, long mask)
>> +{
>> + struct cm32181_chip *cm32181 = iio_priv(indio_dev);
>> + int ret;
>> +
>> + switch (mask) {
>> + case IIO_CHAN_INFO_PROCESSED:
>> + ret = cm32181_get_lux(cm32181);
>> + if (ret < 0)
>> + return ret;
>> + *val = ret;
> Might as well return from here...
> return IIO_VAL_INT;
> instead of bothering with the break.
>> + ret = IIO_VAL_INT;
>> + break;
>> + case IIO_CHAN_INFO_CALIBSCALE:
>> + *val = cm32181->calibscale;
>> + ret = IIO_VAL_INT;
>> + break;
>> + case IIO_CHAN_INFO_INT_TIME:
>> + ret = cm32181_read_als_it(cm32181, val);
>> + if (ret < 0)
>> + return ret;
>> + break;
>> + default:
>> + ret = -EINVAL;
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +static int cm32181_write_raw(struct iio_dev *indio_dev,
>> +      struct iio_chan_spec const *chan,
>> +      int val, int val2, long mask)
>> +{
>> + struct cm32181_chip *cm32181 = iio_priv(indio_dev);
>> + int ret;
>> +
>> + switch (mask) {
>> + case IIO_CHAN_INFO_CALIBSCALE:
>> + cm32181->calibscale = val;
>> + ret = val;
>> + break;
>> + case IIO_CHAN_INFO_INT_TIME:
>> + ret = cm32181_write_als_it(cm32181, val);
>> + if (ret < 0)
>> + return ret;
>> + break;
>> + default:
>> + ret = -EINVAL;
>> + }
>> +
>> + return ret;
>> +}
>> +
>
> Function should have a prefix. Its just possible someone
> will one day introduce a generic get_it_available
> and hence cause a name clash.
>
> hence
> cm32181_get_it_available(...)
>> +static ssize_t get_it_available(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + int i, n, len;
>> +
>> + n = sizeof(als_it_value)/sizeof(als_it_value[0]);
>> + for (i = 0, len = 0; i < n; i++)
>> + len += sprintf(buf + len, "%d ", als_it_value[i]);
>> + return len + sprintf(buf + len, "\n");
>> +}
>> +
>> +static const struct iio_chan_spec cm32181_channels[] = {
>> + {
>> + .type = IIO_LIGHT,
>> + .indexed = 0,
>> + .channel = 0,
>> + .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, get_it_available, NULL, 0);
>> +
>> +static struct attribute *cm32181_attributes[] = {
>> + &iio_dev_attr_in_illuminance_integration_time_available.dev_attr.attr,
>> + NULL,
>> +};
>> +
>> +static const struct attribute_group cm32181_attribute_group = {
>> + .attrs = cm32181_attributes
>> +};
>> +
>> +static const struct iio_info cm32181_info = {
>> + .driver_module = THIS_MODULE,
>> + .read_raw = &cm32181_read_raw,
>> + .write_raw = &cm32181_write_raw,
>> + .attrs = &cm32181_attribute_group,
>> +};
>> +
>> +static int cm32181_probe(struct i2c_client *client,
>> + const struct i2c_device_id *id)
>> +{
>> + struct cm32181_chip *cm32181;
>> + struct iio_dev *indio_dev;
>> + int ret;
>> +
>> + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*cm32181));
>> + if (!indio_dev) {
>> + dev_err(&client->dev, "devm_iio_device_alloc failed\n");
>> + return -ENOMEM;
>> + }
>> +
>> + cm32181 = iio_priv(indio_dev);
>> + i2c_set_clientdata(client, indio_dev);
>> + cm32181->client = client;
>> +
>> + mutex_init(&cm32181->lock);
>> + indio_dev->dev.parent = &client->dev;
>> + indio_dev->channels = cm32181_channels;
>> + indio_dev->num_channels = ARRAY_SIZE(cm32181_channels);
>> + indio_dev->info = &cm32181_info;
>> + indio_dev->name = id->name;
>> + indio_dev->modes = INDIO_DIRECT_MODE;
>> +
>> + ret = cm32181_reg_init(cm32181);
>> + if (ret) {
>> + dev_err(&client->dev,
>> + "%s: register init failed\n",
>> + __func__);
> return ret;
>> + goto error_disable_reg;
>> + }
>> +
>> + ret = iio_device_register(indio_dev);
>> + if (ret) {
>> + dev_err(&client->dev,
>> + "%s: regist device failed\n",
>> + __func__);
> return ret
>> + goto error_disable_reg;
>> + }
>> +
>> + return 0;
>> +
> Don't bother with this - just return directly when the errors
> occur. See above.
>> +error_disable_reg:
>> + return ret;
>> +}
>> +
>
> As mentioned before, the staging-next tree includes
> devm_iio_device_register and if you use that, then no
> remove funciton will be needed.
>
>> +static int cm32181_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 cm32181_id[] = {
>> + { "cm32181", 0 },
>> + { }
>> +};
>> +
>> +MODULE_DEVICE_TABLE(i2c, cm32181_id);
>> +
>> +static const struct of_device_id cm32181_of_match[] = {
>> + { .compatible = "capella,cm32181" },
>> + { }
>> +};
>> +
>> +static struct i2c_driver cm32181_driver = {
>> + .driver = {
>> + .name = "cm32181",
>> + .of_match_table = of_match_ptr(cm32181_of_match),
>> + .owner = THIS_MODULE,
>> + },
>> + .id_table       = cm32181_id,
>> + .probe = cm32181_probe,
>> + .remove = cm32181_remove,
>> +};
>> +
>> +module_i2c_driver(cm32181_driver);
>> +
>> +MODULE_AUTHOR("Kevin Tsai <ktsai@capellamicro.com>");
>> +MODULE_DESCRIPTION("CM32181 ambient light sensor driver");
>> +MODULE_LICENSE("GPL");
>>