Message-ID: <520956A8.3050808@kernel.org>
Date:	Mon, 12 Aug 2013 22:42:00 +0100
From:	Jonathan Cameron <jic23@...nel.org>
To:	Peter Meerwald <pmeerw@...erw.net>
CC:	Kevin Tsai <ktsai@...ellamicro.com>,
	Jonathan Cameron <jic23@....ac.uk>,
	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org
Subject: Re: [PATCH 1/1] Added Capella CM3218 Ambient Light Sensor IIO driver.

On 08/12/13 19:11, Peter Meerwald wrote:
> 
>>  drivers/iio/light/Kconfig  |  10 +
>>  drivers/iio/light/Makefile |   1 +
>>  drivers/iio/light/cm3218.c | 589 +++++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 600 insertions(+)
>>  create mode 100644 drivers/iio/light/cm3218.c
> 
> not much changed since last revision :(
> some comments inline...
> 
>> diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
>> index 5ef1a39..dd1ea80 100644
>> --- a/drivers/iio/light/Kconfig
>> +++ b/drivers/iio/light/Kconfig
>> @@ -15,6 +15,16 @@ config ADJD_S311
>>  	 This driver can also be built as a module.  If so, the module
>>  	 will be called adjd_s311.
>>  
>> +config SENSORS_CM3218
>> +        tristate "CM3218 Ambient Light Sensor"
>> +        depends on I2C
>> +        help
>> +         Say Y here if you have a Capella Micro CM3218 Ambient Light Sensor.
>> +
>> +         To compile this driver as a module, choose M here.  This module
>> +         will be called to 'cm3218'.  It will access ALS data via iio sysfs.
> 
> will be called 'cm3218'.  It will provide access to ALS data via iio 
> sysfs.
> 
>> +         This is recommended.
> 
> I think this should be dropped; or do you mean one should prefer the 
> modules?
> 
>> +
>>  config SENSORS_LM3533
>>  	tristate "LM3533 ambient light sensor"
>>  	depends on MFD_LM3533
>> diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
>> index 040d9c7..c4ebe37 100644
>> --- a/drivers/iio/light/Makefile
>> +++ b/drivers/iio/light/Makefile
>> @@ -3,6 +3,7 @@
>>  #
>>  
>>  obj-$(CONFIG_ADJD_S311)		+= adjd_s311.o
>> +obj-$(CONFIG_SENSORS_CM3218)    += cm3218.o
>>  obj-$(CONFIG_SENSORS_LM3533)	+= lm3533-als.o
>>  obj-$(CONFIG_SENSORS_TSL2563)	+= tsl2563.o
>>  obj-$(CONFIG_VCNL4000)		+= vcnl4000.o
>> diff --git a/drivers/iio/light/cm3218.c b/drivers/iio/light/cm3218.c
>> new file mode 100644
>> index 0000000..1989fbb
>> --- /dev/null
>> +++ b/drivers/iio/light/cm3218.c
>> @@ -0,0 +1,589 @@
>> +/*
>> + * A iio driver for CM3218 Ambient Light Sensor.
>> + *
>> + * IIO driver for monitoring ambient light intensity in lux.
>> + *
>> + * Copyright (c) 2013, Capella Microsystems Inc.
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful, but WITHOUT
>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
>> + * more details.
>> + *
>> + * You should have received a copy of the GNU General Public License along
>> + * with this program; if not, write to the Free Software Foundation, Inc.,
>> + * 51 Franklin Street, Fifth Floor, Boston, MA	02110-1301, USA.
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/i2c.h>
>> +#include <linux/err.h>
>> +#include <linux/mutex.h>
>> +#include <linux/slab.h>
>> +
>> +#if 0	/* ChromeOS still uses old API */
>> +#include "../iio.h"
>> +#include "../sysfs.h"
>> +#define	IIO_DEVICE_ALLOC	iio_allocate_device
>> +#define	IIO_DEVICE_FREE		iio_free_device
>> +#else
> 
> old kernels are not supported; drop this and use the correct funtion 
> directly
> 
> maybe you want to use devm_iio_device_alloc() introduced recently?
Definitely given you will be rerolling the driver anyway.

> 
>> +#include <linux/iio/iio.h>
>> +#include <linux/iio/sysfs.h>
>> +#define	IIO_DEVICE_ALLOC	iio_device_alloc
>> +#define	IIO_DEVICE_FREE		iio_device_free
>> +#endif	/* 0 */
>> +
>> +/*
>> + * SMBus ARA address
>> + */
>> +#define	CM3218_ADDR_ARA			0x0C
>> +
>> +/*
>> + * CM3218 CMD Registers
>> + */
>> +#define	CM3218_REG_ADDR_CMD		0x00
>> +#define	CM3218_CMD_ALS_SD		0x0001
>> +#define	CM3218_CMD_ALS_INT_EN		0x0002
>> +#define	CM3218_CMD_ALS_IT_SHIFT		6
>> +#define	CM3218_CMD_ALS_IT_MASK		(3 << CM3218_CMD_ALS_IT_SHIFT)
>> +#define	CM3218_CMD_ALS_IT_05T		(0 << CM3218_CMD_ALS_IT_SHIFT)
>> +#define	CM3218_CMD_ALS_IT_1T		(1 << CM3218_CMD_ALS_IT_SHIFT)
>> +#define	CM3218_CMD_ALS_IT_2T		(2 << CM3218_CMD_ALS_IT_SHIFT)
>> +#define	CM3218_CMD_ALS_IT_4T		(3 << CM3218_CMD_ALS_IT_SHIFT)
>> +#define	CM3218_DEFAULT_CMD		(CM3218_CMD_ALS_IT_1T)
> 
> parenthesis not necessary here: (CM3218_CMD_ALS_IT_1T)
> 
>> +
>> +#define	CM3218_REG_ADDR_ALS_WH		0x01
>> +#define	CM3218_DEFAULT_ALS_WH		0xFFFF
>> +
>> +#define	CM3218_REG_ADDR_ALS_WL		0x02
>> +#define	CM3218_DEFAULT_ALS_WL		0x0000
>> +
>> +#define	CM3218_REG_ADDR_ALS		0x04
>> +
>> +#define	CM3218_REG_ADDR_STATUS		0x06
>> +
>> +#define	CM3218_REG_ADDR_ID		0x07
>> +
>> +/*
>> + * Software Parameters
>> + */
> 
> single line comment: /* Software Parameters */
> 
>> +#define	CM3218_MAX_CACHE_REGS		(0x03+1)	/* Reg.0x00 to 0x03 */
>> +
>> +/*
>> + * Features
>> + */
> 
> single line comment
> 
>> +#define	CM3218_DEBUG
>> +
>> +static const unsigned short normal_i2c[] = {
>> +	0x10, 0x48, I2C_CLIENT_END };
>> +
>> +struct cm3218_chip {
>> +	struct i2c_client	*client;
>> +	struct mutex		lock;
>> +	unsigned int		lensfactor;
>> +	bool			suspended;
>> +	u16			reg_cache[CM3218_MAX_CACHE_REGS];
>> +};
>> +
>> +static int cm3218_read_ara(struct i2c_client *client)
>> +{
>> +	int status;
>> +	unsigned short addr;
>> +
>> +	addr = client->addr;
>> +	client->addr = CM3218_ADDR_ARA;
>> +	status = i2c_smbus_read_byte(client);
>> +	client->addr = addr;
>> +
>> +	if (status < 0)
>> +		return -ENODEV;
>> +
>> +	return 0;
>> +}
>> +
>> +static int cm3218_write(struct i2c_client *client, u8 reg, u16 value)
>> +{
>> +	int ret;
>> +	struct cm3218_chip *chip = iio_priv(i2c_get_clientdata(client));
>> +
>> +#ifdef	CM3218_DEBUG
>> +	dev_err(&client->dev,
>> +		"Write to device register 0x%02X with 0x%04X\n", reg, value);
> 
> dev_dbg()?
> 
>> +#endif	/* CM3218_DEBUG */
>> +	ret = i2c_smbus_write_word_data(client, reg, value);
>> +	if (ret) {
> 
> ret < 0?
> 
>> +		dev_err(&client->dev, "Write to device fails: 0x%x\n", ret);
>> +	} else {
>> +		/* Update cache */
>> +		if (reg < CM3218_MAX_CACHE_REGS)
>> +			chip->reg_cache[reg] = value;
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +static int cm3218_read(struct i2c_client *client, u8 reg)
>> +{
>> +	int status;
>> +	struct cm3218_chip *chip = iio_priv(i2c_get_clientdata(client));
>> +
>> +	if (reg < CM3218_MAX_CACHE_REGS) {
>> +		status = chip->reg_cache[reg];
>> +	} else {
>> +		status = i2c_smbus_read_word_data(client, reg);
>> +		if (status < 0) {
>> +			dev_err(&client->dev,
>> +				"Error in reading Reg.0x%02X\n", reg);
>> +			return status;
> 
> return not needed here
> 
>> +		}
>> +#ifdef	CM3218_DEBUG
>> +		dev_err(&client->dev,
>> +			"Read from device register 0x%02X = 0x%04X\n",
>> +			reg, status);
>> +#endif	/* CM3218_DEBUG */
>> +	}
>> +
>> +	return status;
>> +}
>> +
>> +static int cm3218_read_sensor_input(struct i2c_client *client)
>> +{
>> +	int status;
>> +
>> +	status = cm3218_read(client, CM3218_REG_ADDR_ALS);
>> +	if (status < 0)
>> +		return status;
>> +
>> +	dev_vdbg(&client->dev, "lux = %u\n", status);
>> +
>> +	return status;
>> +}
> 
> drop this function and inline into read_lux()
> 
>> +
>> +static int cm3218_read_lux(struct i2c_client *client, int *lux)
>> +{
>> +	struct cm3218_chip *chip = iio_priv(i2c_get_clientdata(client));
>> +	int lux_data;
>> +
>> +	lux_data = cm3218_read_sensor_input(client);
>> +
>> +	if (lux_data < 0)
>> +		return lux_data;
>> +
>> +	*lux  = lux_data * chip->lensfactor;
>> +	*lux /= 1000;
>> +	return 0;
>> +}
>> +
>> +/* Sysfs interface */
>> +/* lensfactor */
> 
> use multi-line comment
> 
>> +static ssize_t show_lensfactor(struct device *dev,
>> +			struct device_attribute *attr, char *buf)
>> +{
>> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
>> +	struct cm3218_chip *chip = iio_priv(indio_dev);
> 
> struct cm3218_chip *chip = iio_priv(dev_get_drvdata(dev));
> 
>> +
>> +	return sprintf(buf, "%d\n", chip->lensfactor);
>> +}
> 
> you don't need this, handled by channel read/write below
> 
>> +
>> +static ssize_t store_lensfactor(struct device *dev,
>> +		struct device_attribute *attr, const char *buf, size_t count)
>> +{
>> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
>> +	struct cm3218_chip *chip = iio_priv(indio_dev);
>> +	unsigned long lval;
>> +
>> +	if (kstrtoul(buf, 10, &lval))
>> +		return -EINVAL;
>> +
>> +	mutex_lock(&chip->lock);
>> +	chip->lensfactor = lval;
>> +	mutex_unlock(&chip->lock);
>> +
>> +	return count;
>> +}
> 
> you don't need this, handled by channel read/write below
> no range checking??
> 
>> +
>> +static ssize_t get_sensor_data(struct device *dev, char *buf)
>> +{
>> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
>> +	struct cm3218_chip *chip = iio_priv(indio_dev);
>> +	struct i2c_client *client = chip->client;
>> +	int value = 0;
>> +	int status;
>> +
>> +	mutex_lock(&chip->lock);
>> +	if (chip->suspended) {
>> +		mutex_unlock(&chip->lock);
>> +		return -EBUSY;
>> +	}
>> +
>> +	 status = cm3218_read_lux(client, &value);
> 
> extra space at beginning of line
> 
>> +
>> +	if (status < 0) {
>> +		dev_err(&client->dev, "Error in Reading data");
> 
> reading
> 
>> +		mutex_unlock(&chip->lock);
>> +		return status;
>> +	}
>> +
>> +	mutex_unlock(&chip->lock);
>> +
>> +	return sprintf(buf, "%d\n", value);
>> +}
>> +
>> +
>> +/* Read lux */
>> +static ssize_t show_lux(struct device *dev,
>> +	struct device_attribute *devattr, char *buf)
>> +{
>> +	return get_sensor_data(dev, buf);
>> +}
> 
> drop this; use channels to present data
> 
>> +
>> +#ifdef	CM3218_DEBUG
>> +/* windows_high */
>> +static ssize_t show_cmd(struct device *dev,
>> +	struct device_attribute *attr, char *buf)
>> +{
>> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
>> +	struct cm3218_chip *chip = iio_priv(indio_dev);
>> +	struct i2c_client *client = chip->client;
>> +	int status;
>> +
>> +	status = cm3218_read(client, CM3218_REG_ADDR_CMD);
>> +	if (status < 0) {
>> +		dev_err(dev, "Error in getting CM3218_REG_ADDR_CMD\n");
>> +		return status;
>> +	}
>> +
>> +	return sprintf(buf, "%u\n", status);
>> +}
> 
> I'd rather drop the debugging stuff; you could use 
> probably use iio_info.debugfs_reg_access:
> 
>> +
>> +static ssize_t store_cmd(struct device *dev,
>> +		struct device_attribute *attr, const char *buf, size_t count)
>> +{
>> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
>> +	struct cm3218_chip *chip = iio_priv(indio_dev);
>> +	struct i2c_client *client = chip->client;
>> +	int status;
>> +	unsigned long lval;
>> +
>> +	if (kstrtoul(buf, 10, &lval))
>> +		return -EINVAL;
>> +
>> +	mutex_lock(&chip->lock);
>> +	if (lval > 0x10000)
> 
>> = maybe?
> 
>> +		lval = 0xFFFF;
>> +	status = cm3218_write(client, CM3218_REG_ADDR_CMD, (u16)lval);
>> +	if (status < 0) {
>> +		mutex_unlock(&chip->lock);
>> +		dev_err(dev, "Error in setting CM3218_REG_ADDR_CMD\n");
>> +		return status;
>> +	}
>> +	mutex_unlock(&chip->lock);
>> +
>> +	return count;
>> +}
>> +
>> +/* status */
>> +static ssize_t show_status(struct device *dev,
>> +			struct device_attribute *attr, char *buf)
>> +{
>> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
>> +	struct cm3218_chip *chip = iio_priv(indio_dev);
>> +	struct i2c_client *client = chip->client;
>> +	int status;
>> +
>> +	status = cm3218_read(client, CM3218_REG_ADDR_STATUS);
>> +	if (status < 0) {
>> +		dev_err(dev, "Error in getting CM3218_REG_ADDR_STATUS\n");
>> +		return status;
>> +	}
>> +
>> +	return sprintf(buf, "%u\n", status);
>> +}
>> +
>> +#endif	/* CM3218_DEBUG */
>> +
>> +/* Channel IO */
>> +static int cm3218_write_raw(struct iio_dev *indio_dev,
>> +			      struct iio_chan_spec const *chan,
>> +			      int val,
>> +			      int val2,
>> +			      long mask)
>> +{
>> +	struct cm3218_chip *chip = iio_priv(indio_dev);
>> +	int ret = -EINVAL;
> 
> ret is not used, only assigned
> 
>> +
>> +	mutex_lock(&chip->lock);
>> +	if (mask == IIO_CHAN_INFO_CALIBSCALE && chan->type == IIO_LIGHT) {
>> +		chip->lensfactor = val;
>> +		ret = 0;
>> +	}
>> +	mutex_unlock(&chip->lock);
>> +
>> +	return 0;
>> +}
>> +
>> +static int cm3218_read_raw(struct iio_dev *indio_dev,
>> +			     struct iio_chan_spec const *chan,
>> +			     int *val,
>> +			     int *val2,
>> +			     long mask)
>> +{
>> +	int ret = -EINVAL;
>> +	struct cm3218_chip *chip = iio_priv(indio_dev);
>> +	struct i2c_client *client = chip->client;
>> +
>> +	mutex_lock(&chip->lock);
>> +	if (chip->suspended) {
>> +		mutex_unlock(&chip->lock);
>> +		return -EBUSY;
>> +	}
>> +	switch (mask) {
>> +	case 0:
> 
> INFO_RAW? or INFO_PROCESSED?
> 
>> +		ret = cm3218_read_lux(client, val);
>> +		if (!ret)
>> +			ret = IIO_VAL_INT;
> 
> if (ret >= 0) ??
> 
>> +		break;
>> +	case IIO_CHAN_INFO_CALIBSCALE:
>> +		*val = chip->lensfactor;
>> +		ret = IIO_VAL_INT_PLUS_MICRO;
>> +		break;
>> +	default:
>> +		break;
>> +	}
>> +	mutex_unlock(&chip->lock);
>> +	return ret;
>> +}
>> +
>> +#define IIO_CHAN_INFO_SEPARATE_BIT(type) BIT(type*2 + 1)
>> +#define IIO_CHAN_INFO_CALIBSCALE_SEPARATE_BIT                   \
>> +	IIO_CHAN_INFO_SEPARATE_BIT(IIO_CHAN_INFO_CALIBSCALE)
> 
> only needed for old kernels
> 
>> +
>> +static const struct iio_chan_spec cm3218_channels[] = {
>> +	{
>> +		.type = IIO_LIGHT,
>> +		.indexed = 1,
> 
> there is only one channel, no need to index
> 
>> +		.channel = 0,
>> +		.info_mask = IIO_CHAN_INFO_CALIBSCALE_SEPARATE_BIT,
> 
> INFO_RAW/PROCESSED?
> 
>> +	}
>> +};
>> +
>> +static IIO_DEVICE_ATTR(illuminance0_input, S_IRUGO, show_lux, NULL, 0);
>> +static IIO_DEVICE_ATTR(illuminance0_calibscale, S_IRUGO | S_IWUSR,
>> +					show_lensfactor, store_lensfactor, 0);
> 
>> +#ifdef	CM3218_DEBUG
>> +static IIO_DEVICE_ATTR(cmd, S_IRUGO | S_IWUSR, show_cmd, store_cmd, 0);
>> +static IIO_DEVICE_ATTR(status, S_IRUGO, show_status, NULL, 0);
>> +#endif	/* CM3218_DEBUG */
>> +
>> +#define CM3218_DEV_ATTR(name) (&iio_dev_attr_##name.dev_attr.attr)
>> +#define CM3218_CONST_ATTR(name) (&iio_const_attr_##name.dev_attr.attr)
>> +static struct attribute *cm3218_attributes[] = {
>> +	CM3218_DEV_ATTR(illuminance0_input),
>> +	CM3218_DEV_ATTR(illuminance0_calibscale),
>> +#ifdef	CM3218_DEBUG
>> +	CM3218_DEV_ATTR(cmd),
>> +	CM3218_DEV_ATTR(status),
>> +#endif	/* CM3218_DEBUG */
>> +	NULL
>> +};
>> +
>> +static const struct attribute_group cm3218_group = {
>> +	.attrs = cm3218_attributes,
>> +};
>> +
>> +static int cm3218_chip_init(struct i2c_client *client)
>> +{
>> +	struct cm3218_chip *chip = iio_priv(i2c_get_clientdata(client));
>> +	int status, i;
>> +
>> +	memset(chip->reg_cache, 0, sizeof(chip->reg_cache));
>> +
>> +	for (i = 0; i < 5; i++) {
>> +		status = cm3218_write(client, CM3218_REG_ADDR_CMD,
>> +				CM3218_CMD_ALS_SD);
>> +		if (status >= 0)
>> +			break;
>> +		cm3218_read_ara(client);
> 
> why 5 times? no sleep?
> 
>> +	}
>> +
>> +	status = cm3218_write(client, CM3218_REG_ADDR_CMD, CM3218_DEFAULT_CMD);
>> +	if (status < 0) {
>> +		dev_err(&client->dev, "Init CM3218 CMD fails\n");
>> +		return status;
>> +	}
>> +
>> +
>> +	/* Clean interrupt status */
>> +	cm3218_read(client, CM3218_REG_ADDR_STATUS);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct iio_info cm3218_info = {
>> +	.attrs = &cm3218_group,
>> +	.driver_module = THIS_MODULE,
>> +	.read_raw = &cm3218_read_raw,
>> +	.write_raw = &cm3218_write_raw,
>> +};
>> +
>> +static int cm3218_probe(struct i2c_client *client,
>> +			 const struct i2c_device_id *id)
>> +{
>> +	struct cm3218_chip *chip;
>> +	struct iio_dev *indio_dev;
>> +	int err;
>> +
>> +	indio_dev = IIO_DEVICE_ALLOC(sizeof(*chip));
>> +	if (indio_dev == NULL) {
>> +		dev_err(&client->dev, "iio allocation fails\n");
> 
> drop error msg
> 
>> +		err = -ENOMEM;
>> +		goto exit;
>> +	}
>> +	chip = iio_priv(indio_dev);
>> +	chip->client = client;
>> +	i2c_set_clientdata(client, indio_dev);
>> +
>> +	mutex_init(&chip->lock);
>> +
>> +	chip->lensfactor = 1000;
>> +	chip->suspended = false;
>> +
>> +	err = cm3218_chip_init(client);
>> +	if (err)
>> +		goto exit_iio_free;
>> +
>> +	indio_dev->info = &cm3218_info;
>> +	indio_dev->channels = cm3218_channels;
>> +	indio_dev->num_channels = ARRAY_SIZE(cm3218_channels);
>> +	indio_dev->name = id->name;
>> +	indio_dev->dev.parent = &client->dev;
>> +	indio_dev->modes = INDIO_DIRECT_MODE;
>> +	err = iio_device_register(indio_dev);
>> +	if (err) {
>> +		dev_err(&client->dev, "iio registration fails\n");
>> +		goto exit_iio_free;
>> +	}
>> +
>> +	return 0;
>> +exit_iio_free:
>> +	IIO_DEVICE_FREE(indio_dev);
>> +exit:
>> +	return err;
>> +}
>> +
>> +static int cm3218_detect(struct i2c_client *client,
>> +				   struct i2c_board_info *info)
>> +{
>> +	struct i2c_adapter *adapter = client->adapter;
>> +	const char *name = NULL;
>> +	int id;
>> +
>> +	cm3218_read_ara(client);
>> +
>> +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
>> +		return -ENODEV;
>> +
>> +	id = cm3218_read(client, CM3218_REG_ADDR_ID);
>> +	if (id < 0)
>> +		return -ENODEV;
>> +
>> +	switch (id&0xFF) {
>> +	case 0x18:
>> +		name = "cm3218";
>> +		break;
>> +	default:
>> +		return -ENODEV;
>> +	}
>> +
>> +	strlcpy(info->type, name, I2C_NAME_SIZE);
>> +
>> +	return 0;
>> +}
> 
> drop detect code
> 
>> +
>> +static int cm3218_remove(struct i2c_client *client)
>> +{
>> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
>> +
>> +	dev_dbg(&client->dev, "%s()\n", __func__);
>> +	iio_device_unregister(indio_dev);
>> +	IIO_DEVICE_FREE(indio_dev);
>> +
>> +	return 0;
>> +}
>> +
>> +#ifdef CONFIG_PM_SLEEP
>> +static int cm3218_suspend(struct device *dev)
>> +{
>> +	struct cm3218_chip *chip = iio_priv(dev_get_drvdata(dev));
>> +
>> +	mutex_lock(&chip->lock);
>> +
>> +	/* Since this driver uses only polling commands, we are by default in
>> +	 * auto shutdown (ie, power-down) mode.
>> +	 * So we do not have much to do here.
>> +	 */
>> +	chip->suspended = true;
>> +
>> +	mutex_unlock(&chip->lock);
>> +	return 0;
>> +}
>> +
>> +static int cm3218_resume(struct device *dev)
>> +{
>> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
>> +	struct cm3218_chip *chip = iio_priv(indio_dev);
>> +	struct i2c_client *client = chip->client;
>> +	int err;
>> +
>> +	mutex_lock(&chip->lock);
>> +
>> +	err = cm3218_chip_init(client);
>> +	if (!err)
>> +		chip->suspended = false;
>> +
>> +	mutex_unlock(&chip->lock);
>> +	return err;
>> +}
>> +
>> +static SIMPLE_DEV_PM_OPS(cm3218_pm_ops, cm3218_suspend, cm3218_resume);
>> +#define CM3218_PM_OPS (&cm3218_pm_ops)
>> +#else
>> +#define CM3218_PM_OPS NULL
>> +#endif
>> +
>> +static const struct i2c_device_id cm3218_id[] = {
>> +	{"cm3218", 0},
>> +	{}
>> +};
>> +
>> +MODULE_DEVICE_TABLE(i2c, cm3218_id);
>> +
>> +static const struct of_device_id cm3218_of_match[] = {
>> +	{ .compatible = "invn,cm3218", },
>> +	{}
>> +};
>> +MODULE_DEVICE_TABLE(of, cm3218_of_match);
>> +
>> +static struct i2c_driver cm3218_driver = {
>> +	.class = I2C_CLASS_HWMON,
>> +	.driver = {
>> +		.name = "cm3218",
>> +		.pm = CM3218_PM_OPS,
>> +		.owner = THIS_MODULE,
>> +		.of_match_table = cm3218_of_match,
>> +	},
>> +	.probe = cm3218_probe,
>> +	.remove = cm3218_remove,
>> +	.id_table = cm3218_id,
>> +	.detect = cm3218_detect,
>> +	.address_list = normal_i2c,
>> +};
>> +module_i2c_driver(cm3218_driver);
>> +
>> +MODULE_DESCRIPTION("CM3218 Ambient Light Sensor driver");
>> +MODULE_LICENSE("GPL");
>>
> 
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