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

[Jonathan Cameron <jic23@kernel.org>]

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");
>