[PATCH] Staging: iio: cdc: Remove unused macro

[PATCH] Staging: iio: cdc: Remove unused macro

[Shraddha Barke]

Remove the macro since it's not used anywhere throughout the kernel

Signed-off-by: Shraddha Barke <shraddha.6596@gmail.com>
---
 drivers/staging/iio/cdc/ad7746.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/staging/iio/cdc/ad7746.c b/drivers/staging/iio/cdc/ad7746.c
index 10fa372..f5a807c 100644
--- a/drivers/staging/iio/cdc/ad7746.c
+++ b/drivers/staging/iio/cdc/ad7746.c
@@ -43,7 +43,6 @@
 #define AD7746_REG_CAP_GAINH		15
 #define AD7746_REG_CAP_GAINL		16
 #define AD7746_REG_VOLT_GAINH		17
-#define AD7746_REG_VOLT_GAINL		18
 
 /* Status Register Bit Designations (AD7746_REG_STATUS) */
 #define AD7746_STATUS_EXCERR		BIT(3)
-- 
2.1.4

Re: [PATCH] Staging: iio: cdc: Remove unused macro

[Jonathan Cameron]

On 16/09/15 13:44, Shraddha Barke wrote:
> Remove the macro since it's not used anywhere throughout the kernel
> 
> Signed-off-by: Shraddha Barke <shraddha.6596@gmail.com>
Whilst I have no objection to cleanup patches like this in general,
I would prefer a more thorough look at the driver.  For example, the
macro 2 lines above isn't used either.

So I'm not going to take this patch as it adds unnecessary noise.
If you want to take a good look at the whole driver and see what
else needs cleaning up then that would be great!

Speaking of which.  Lars, do you guys have any plans to get these devices
out of staging anytime soon? (or know of anyone else who does).
If not perhaps some guidance would help Shradda make that move if he is
interested in doing so?

Thanks,

Jonathan
> ---
>  drivers/staging/iio/cdc/ad7746.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/staging/iio/cdc/ad7746.c b/drivers/staging/iio/cdc/ad7746.c
> index 10fa372..f5a807c 100644
> --- a/drivers/staging/iio/cdc/ad7746.c
> +++ b/drivers/staging/iio/cdc/ad7746.c
> @@ -43,7 +43,6 @@
>  #define AD7746_REG_CAP_GAINH		15
>  #define AD7746_REG_CAP_GAINL		16
>  #define AD7746_REG_VOLT_GAINH		17
> -#define AD7746_REG_VOLT_GAINL		18
>  
>  /* Status Register Bit Designations (AD7746_REG_STATUS) */
>  #define AD7746_STATUS_EXCERR		BIT(3)
> 

Re: [PATCH] Staging: iio: cdc: Remove unused macro

[Shraddha Barke]

On Sun, 20 Sep 2015, Jonathan Cameron wrote:

> On 16/09/15 13:44, Shraddha Barke wrote:
>> Remove the macro since it's not used anywhere throughout the kernel
>>
>> Signed-off-by: Shraddha Barke <shraddha.6596@gmail.com>
> Whilst I have no objection to cleanup patches like this in general,
> I would prefer a more thorough look at the driver.  For example, the
> macro 2 lines above isn't used either.
>
> So I'm not going to take this patch as it adds unnecessary noise.
> If you want to take a good look at the whole driver and see what
> else needs cleaning up then that would be great!
>
> Speaking of which.  Lars, do you guys have any plans to get these devices
> out of staging anytime soon? (or know of anyone else who does).
> If not perhaps some guidance would help Shradda make that move if he is
> interested in doing so?

Yes I'm interested in working on this. Please provide me the necessary 
guidance so that I can start on those lines.

Thanks,

Shraddha
>
> Thanks,
>
> Jonathan
>> ---
>>  drivers/staging/iio/cdc/ad7746.c | 1 -
>>  1 file changed, 1 deletion(-)
>>
>> diff --git a/drivers/staging/iio/cdc/ad7746.c b/drivers/staging/iio/cdc/ad7746.c
>> index 10fa372..f5a807c 100644
>> --- a/drivers/staging/iio/cdc/ad7746.c
>> +++ b/drivers/staging/iio/cdc/ad7746.c
>> @@ -43,7 +43,6 @@
>>  #define AD7746_REG_CAP_GAINH		15
>>  #define AD7746_REG_CAP_GAINL		16
>>  #define AD7746_REG_VOLT_GAINH		17
>> -#define AD7746_REG_VOLT_GAINL		18
>>
>>  /* Status Register Bit Designations (AD7746_REG_STATUS) */
>>  #define AD7746_STATUS_EXCERR		BIT(3)
>>
>
>

Re: [PATCH] Staging: iio: cdc: Remove unused macro

[Jonathan Cameron]

Hi Shraddha,

To get you started, I've quickly faked up a patch of the driver
in it's current location to let me 'review' it. Note this was
a very quick review so I may well have missed lots. Lars
may have more comments and Michael may hopefully surface as well.

The biggest bit in here is probably the lack of documented
ABI for the 'calibration' attributes.  Off the top of my
head I have no clear idea of what they are for.  Then again
I've never used a CDC and haven't read for this one in years
which probably doesn't help.

Anyhow, lots of coding style related stuff as well similar to
what you found in your initial patch.

Hopefully something to get you started.

Good luck.

Jonathan

p.s. Actually, other than the fact we've gotten tighter on
coding style stuff etc, this driver is in a pretty good state
making a good target for finally getting out of staging.

diff --git a/drivers/staging/iio/cdc/ad7746.c b/drivers/staging/iio/cdc/ad7746.c
new file mode 100644
index 000000000000..e6e9eaa9eab5
--- /dev/null
+++ b/drivers/staging/iio/cdc/ad7746.c
@@ -0,0 +1,791 @@
+/*
+ * AD7746 capacitive sensor driver supporting AD7745, AD7746 and AD7747
+ *
+ * Copyright 2011 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/stat.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#include "ad7746.h"
+
+/*
+ * AD7746 Register Definition
+ */
Single line comment probably should have single line comment syntax.
+
+#define AD7746_REG_STATUS		0
+#define AD7746_REG_CAP_DATA_HIGH	1
+#define AD7746_REG_CAP_DATA_MID		2
+#define AD7746_REG_CAP_DATA_LOW		3
+#define AD7746_REG_VT_DATA_HIGH		4
+#define AD7746_REG_VT_DATA_MID		5
+#define AD7746_REG_VT_DATA_LOW		6
+#define AD7746_REG_CAP_SETUP		7
+#define AD7746_REG_VT_SETUP		8
+#define AD7746_REG_EXC_SETUP		9
+#define AD7746_REG_CFG			10
+#define AD7746_REG_CAPDACA		11
+#define AD7746_REG_CAPDACB		12
+#define AD7746_REG_CAP_OFFH		13
+#define AD7746_REG_CAP_OFFL		14
+#define AD7746_REG_CAP_GAINH		15
+#define AD7746_REG_CAP_GAINL		16
+#define AD7746_REG_VOLT_GAINH		17
+#define AD7746_REG_VOLT_GAINL		18
+
+/* Status Register Bit Designations (AD7746_REG_STATUS) */
+#define AD7746_STATUS_EXCERR		(1 << 3)
+#define AD7746_STATUS_RDY		(1 << 2)
+#define AD7746_STATUS_RDYVT		(1 << 1)
+#define AD7746_STATUS_RDYCAP		(1 << 0)
+
+/* Capacitive Channel Setup Register Bit Designations (AD7746_REG_CAP_SETUP) */
+#define AD7746_CAPSETUP_CAPEN		(1 << 7)
+#define AD7746_CAPSETUP_CIN2		(1 << 6) /* AD7746 only */
+#define AD7746_CAPSETUP_CAPDIFF		(1 << 5)
+#define AD7746_CAPSETUP_CACHOP		(1 << 0)
+
+/* Voltage/Temperature Setup Register Bit Designations (AD7746_REG_VT_SETUP) */
+#define AD7746_VTSETUP_VTEN		(1 << 7)
+#define AD7746_VTSETUP_VTMD_INT_TEMP	(0 << 5)
+#define AD7746_VTSETUP_VTMD_EXT_TEMP	(1 << 5)
+#define AD7746_VTSETUP_VTMD_VDD_MON	(2 << 5)
+#define AD7746_VTSETUP_VTMD_EXT_VIN	(3 << 5)
+#define AD7746_VTSETUP_EXTREF		(1 << 4)
+#define AD7746_VTSETUP_VTSHORT		(1 << 1)
+#define AD7746_VTSETUP_VTCHOP		(1 << 0)
In mixed cases like this, sometimes using the BIT macro
makes sense, sometimes not. Depends on the use.  So
I'd epect the bottom 3 to us BIm, but not the ones
shifted by 5.  That might benefit from a macro though
to wrap up the shift and make it obvious all those shift by 5 elements
are actually in the same 2 bit field.

+
+/* Excitation Setup Register Bit Designations (AD7746_REG_EXC_SETUP) */
+#define AD7746_EXCSETUP_CLKCTRL		(1 << 7)
+#define AD7746_EXCSETUP_EXCON		(1 << 6)
+#define AD7746_EXCSETUP_EXCB		(1 << 5)
+#define AD7746_EXCSETUP_NEXCB		(1 << 4)
+#define AD7746_EXCSETUP_EXCA		(1 << 3)
+#define AD7746_EXCSETUP_NEXCA		(1 << 2)
This lot are probably a good place to use the BIT macro.
+#define AD7746_EXCSETUP_EXCLVL(x)	(((x) & 0x3) << 0)
+
+/* Config Register Bit Designations (AD7746_REG_CFG) */
+#define AD7746_CONF_VTFS(x)		((x) << 6)
+#define AD7746_CONF_CAPFS(x)		((x) << 3)
+#define AD7746_CONF_MODE_IDLE		(0 << 0)
+#define AD7746_CONF_MODE_CONT_CONV	(1 << 0)
+#define AD7746_CONF_MODE_SINGLE_CONV	(2 << 0)
+#define AD7746_CONF_MODE_PWRDN		(3 << 0)
+#define AD7746_CONF_MODE_OFFS_CAL	(5 << 0)
+#define AD7746_CONF_MODE_GAIN_CAL	(6 << 0)
Hmm. Not sure shifting by 0 is all that informative...
+
+/* CAPDAC Register Bit Designations (AD7746_REG_CAPDACx) */
+#define AD7746_CAPDAC_DACEN		(1 << 7)
+#define AD7746_CAPDAC_DACP(x)		((x) & 0x7F)
+
+/*
+ * struct ad7746_chip_info - chip specific information
+ */
Single line should probably have single line comment syntax.
+
+struct ad7746_chip_info {
+	struct i2c_client *client;
+	/*
+	 * Capacitive channel digital filter setup;
+	 * conversion time/update rate setup per channel
+	 */
+	u8	config;
+	u8	cap_setup;
+	u8	vt_setup;
+	u8	capdac[2][2];
+	s8	capdac_set;
+
+	union {
+		__be32 d32;
+		u8 d8[4];
+	} data ____cacheline_aligned;
+};
+
+enum ad7746_chan {
+	VIN,
+	VIN_VDD,
+	TEMP_INT,
+	TEMP_EXT,
+	CIN1,
+	CIN1_DIFF,
+	CIN2,
+	CIN2_DIFF,
+};
+
+static const struct iio_chan_spec ad7746_channels[] = {
+	[VIN] = {
+		.type = IIO_VOLTAGE,
+		.indexed = 1,
+		.channel = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.address = AD7746_REG_VT_DATA_HIGH << 8 |
+			AD7746_VTSETUP_VTMD_EXT_VIN,
+	},
+	[VIN_VDD] = {
+		.type = IIO_VOLTAGE,
+		.indexed = 1,
+		.channel = 1,
+		.extend_name = "supply",
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.address = AD7746_REG_VT_DATA_HIGH << 8 |
+			AD7746_VTSETUP_VTMD_VDD_MON,
+	},
+	[TEMP_INT] = {
+		.type = IIO_TEMP,
+		.indexed = 1,
+		.channel = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+		.address = AD7746_REG_VT_DATA_HIGH << 8 |
+			AD7746_VTSETUP_VTMD_INT_TEMP,
These address fields clearly combine multiple elements.  whilst
concise, this doesn't ease readablility of the code.  See below
for a suggestion on this.
+	},
+	[TEMP_EXT] = {
+		.type = IIO_TEMP,
+		.indexed = 1,
+		.channel = 1,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+		.address = AD7746_REG_VT_DATA_HIGH << 8 |
+			AD7746_VTSETUP_VTMD_EXT_TEMP,
+	},
+	[CIN1] = {
+		.type = IIO_CAPACITANCE,
+		.indexed = 1,
+		.channel = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+		BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_OFFSET),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) |
+		BIT(IIO_CHAN_INFO_SCALE),
+		.address = AD7746_REG_CAP_DATA_HIGH << 8,
+	},
+	[CIN1_DIFF] = {
+		.type = IIO_CAPACITANCE,
+		.differential = 1,
+		.indexed = 1,
+		.channel = 0,
+		.channel2 = 2,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+		BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_OFFSET),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) |
+		BIT(IIO_CHAN_INFO_SCALE),
+		.address = AD7746_REG_CAP_DATA_HIGH << 8 |
+			AD7746_CAPSETUP_CAPDIFF
+	},
+	[CIN2] = {
+		.type = IIO_CAPACITANCE,
+		.indexed = 1,
+		.channel = 1,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+		BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_OFFSET),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) |
+		BIT(IIO_CHAN_INFO_SCALE),
+		.address = AD7746_REG_CAP_DATA_HIGH << 8 |
+			AD7746_CAPSETUP_CIN2,
+	},
+	[CIN2_DIFF] = {
+		.type = IIO_CAPACITANCE,
+		.differential = 1,
+		.indexed = 1,
+		.channel = 1,
+		.channel2 = 3,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+		BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_OFFSET),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) |
+		BIT(IIO_CHAN_INFO_SCALE),
+		.address = AD7746_REG_CAP_DATA_HIGH << 8 |
+			AD7746_CAPSETUP_CAPDIFF | AD7746_CAPSETUP_CIN2,
+	}
+};
+
+/* Values are Update Rate (Hz), Conversion Time (ms) + 1*/
+static const unsigned char ad7746_vt_filter_rate_table[][2] = {
+	{50, 20 + 1}, {31, 32 + 1}, {16, 62 + 1}, {8, 122 + 1},
+};
+
+static const unsigned char ad7746_cap_filter_rate_table[][2] = {
+	{91, 11 + 1}, {84, 12 + 1}, {50, 20 + 1}, {26, 38 + 1},
+	{16, 62 + 1}, {13, 77 + 1}, {11, 92 + 1}, {9, 110 + 1},
+};
+
+static int ad7746_select_channel(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan)
+{
+	struct ad7746_chip_info *chip = iio_priv(indio_dev);
+	int ret, delay;
+	u8 vt_setup, cap_setup;
+
+	switch (chan->type) {
+	case IIO_CAPACITANCE:
This use of part of address strikes me as messy.  I'd have address
hold a look up index that allows the various things combined in address
to be held in a nice easy to follow enumerated array of a structures.
Will give more readable code throughout.
+		cap_setup = (chan->address & 0xFF) | AD7746_CAPSETUP_CAPEN;
+		vt_setup = chip->vt_setup & ~AD7746_VTSETUP_VTEN;
+		delay = ad7746_cap_filter_rate_table[(chip->config >> 3) &
+			0x7][1];
+
+		if (chip->capdac_set != chan->channel) {
+			ret = i2c_smbus_write_byte_data(chip->client,
+				AD7746_REG_CAPDACA,
+				chip->capdac[chan->channel][0]);
+			if (ret < 0)
+				return ret;
+			ret = i2c_smbus_write_byte_data(chip->client,
+				AD7746_REG_CAPDACB,
+				chip->capdac[chan->channel][1]);
+			if (ret < 0)
+				return ret;
+
+			chip->capdac_set = chan->channel;
+		}
+		break;
+	case IIO_VOLTAGE:
+	case IIO_TEMP:
+		vt_setup = (chan->address & 0xFF) | AD7746_VTSETUP_VTEN;
+		cap_setup = chip->cap_setup & ~AD7746_CAPSETUP_CAPEN;
+		delay = ad7746_cap_filter_rate_table[(chip->config >> 6) &
+			0x3][1];
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (chip->cap_setup != cap_setup) {
+		ret = i2c_smbus_write_byte_data(chip->client,
+						AD7746_REG_CAP_SETUP,
+						cap_setup);
+		if (ret < 0)
+			return ret;
+
+		chip->cap_setup = cap_setup;
+	}
+
+	if (chip->vt_setup != vt_setup) {
+		ret = i2c_smbus_write_byte_data(chip->client,
+						AD7746_REG_VT_SETUP,
+						vt_setup);
+		if (ret < 0)
+			return ret;
+
+		chip->vt_setup = vt_setup;
+	}
+
+	return delay;
+}
+
+static inline ssize_t ad7746_start_calib(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf,
+					 size_t len,
+					 u8 regval)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct ad7746_chip_info *chip = iio_priv(indio_dev);
+	bool doit;
+	int ret, timeout = 10;
+
+	ret = strtobool(buf, &doit);
+	if (ret < 0)
+		return ret;
+
+	if (!doit)
+		return 0;
+
+	mutex_lock(&indio_dev->mlock);
+	regval |= chip->config;
+	ret = i2c_smbus_write_byte_data(chip->client, AD7746_REG_CFG, regval);
+	if (ret < 0) {
+		mutex_unlock(&indio_dev->mlock);
+		return ret;
+	}
+
+	do {
+		msleep(20);
+		ret = i2c_smbus_read_byte_data(chip->client, AD7746_REG_CFG);
+		if (ret < 0) {
+			mutex_unlock(&indio_dev->mlock);
+			return ret;
+		}
+	} while ((ret == regval) && timeout--);
+
+	mutex_unlock(&indio_dev->mlock);
+
+	return len;
+}
+
+static ssize_t ad7746_start_offset_calib(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf,
+					 size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	int ret = ad7746_select_channel(indio_dev,
+			      &ad7746_channels[to_iio_dev_attr(attr)->address]);
+	if (ret < 0)
+		return ret;
+
+	return ad7746_start_calib(dev, attr, buf, len,
+				  AD7746_CONF_MODE_OFFS_CAL);
+}
+
+static ssize_t ad7746_start_gain_calib(struct device *dev,
+				       struct device_attribute *attr,
+				       const char *buf,
+				       size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	int ret = ad7746_select_channel(indio_dev,
+			      &ad7746_channels[to_iio_dev_attr(attr)->address]);
+	if (ret < 0)
+		return ret;
+
+	return ad7746_start_calib(dev, attr, buf, len,
+				  AD7746_CONF_MODE_GAIN_CAL);
+}
+
+static IIO_DEVICE_ATTR(in_capacitance0_calibbias_calibration,
+		       S_IWUSR, NULL, ad7746_start_offset_calib, CIN1);
+static IIO_DEVICE_ATTR(in_capacitance1_calibbias_calibration,
+		       S_IWUSR, NULL, ad7746_start_offset_calib, CIN2);
+static IIO_DEVICE_ATTR(in_capacitance0_calibscale_calibration,
+		       S_IWUSR, NULL, ad7746_start_gain_calib, CIN1);
+static IIO_DEVICE_ATTR(in_capacitance1_calibscale_calibration,
+		       S_IWUSR, NULL, ad7746_start_gain_calib, CIN2);
+static IIO_DEVICE_ATTR(in_voltage0_calibscale_calibration,
+		       S_IWUSR, NULL, ad7746_start_gain_calib, VIN);
+
+static ssize_t ad7746_show_cap_filter_rate_setup(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct ad7746_chip_info *chip = iio_priv(indio_dev);
+
+	return sprintf(buf, "%d\n", ad7746_cap_filter_rate_table[
+			(chip->config >> 3) & 0x7][0]);
+}
+
+static ssize_t ad7746_store_cap_filter_rate_setup(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct ad7746_chip_info *chip = iio_priv(indio_dev);
+	u8 data;
+	int ret, i;
+
+	ret = kstrtou8(buf, 10, &data);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < ARRAY_SIZE(ad7746_cap_filter_rate_table); i++)
+		if (data >= ad7746_cap_filter_rate_table[i][0])
+			break;
+
+	if (i >= ARRAY_SIZE(ad7746_cap_filter_rate_table))
+		i = ARRAY_SIZE(ad7746_cap_filter_rate_table) - 1;
+
+	mutex_lock(&indio_dev->mlock);
+	chip->config &= ~AD7746_CONF_CAPFS(0x7);
+	chip->config |= AD7746_CONF_CAPFS(i);
+	mutex_unlock(&indio_dev->mlock);
+
+	return len;
+}
+
+static ssize_t ad7746_show_vt_filter_rate_setup(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct ad7746_chip_info *chip = iio_priv(indio_dev);
+
+	return sprintf(buf, "%d\n", ad7746_vt_filter_rate_table[
+			(chip->config >> 6) & 0x3][0]);
+}
+
+static ssize_t ad7746_store_vt_filter_rate_setup(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct ad7746_chip_info *chip = iio_priv(indio_dev);
+	u8 data;
+	int ret, i;
+
+	ret = kstrtou8(buf, 10, &data);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < ARRAY_SIZE(ad7746_vt_filter_rate_table); i++)
+		if (data >= ad7746_vt_filter_rate_table[i][0])
+			break;
+
+	if (i >= ARRAY_SIZE(ad7746_vt_filter_rate_table))
+		i = ARRAY_SIZE(ad7746_vt_filter_rate_table) - 1;
+
+	mutex_lock(&indio_dev->mlock);
+	chip->config &= ~AD7746_CONF_VTFS(0x3);
+	chip->config |= AD7746_CONF_VTFS(i);
+	mutex_unlock(&indio_dev->mlock);
+
+	return len;
+}
+
+static IIO_DEVICE_ATTR(in_capacitance_sampling_frequency,
+		       S_IRUGO | S_IWUSR, ad7746_show_cap_filter_rate_setup,
+			ad7746_store_cap_filter_rate_setup, 0);
+
+static IIO_DEVICE_ATTR(in_voltage_sampling_frequency,
+		       S_IRUGO | S_IWUSR, ad7746_show_vt_filter_rate_setup,
+		       ad7746_store_vt_filter_rate_setup, 0);
+
+static IIO_CONST_ATTR(in_voltage_sampling_frequency_available, "50 31 16 8");
+static IIO_CONST_ATTR(in_capacitance_sampling_frequency_available,
+		       "91 84 50 26 16 13 11 9");
+
+static struct attribute *ad7746_attributes[] = {
+	&iio_dev_attr_in_capacitance_sampling_frequency.dev_attr.attr,
+	&iio_dev_attr_in_voltage_sampling_frequency.dev_attr.attr,
Can now be done as a standard info_mask element - in this case
these would be shared_by_type.

+	&iio_dev_attr_in_capacitance0_calibbias_calibration.dev_attr.attr,
These need docummenting / understanding which I don't have right now!
+	&iio_dev_attr_in_capacitance0_calibscale_calibration.dev_attr.attr,
+	&iio_dev_attr_in_capacitance1_calibscale_calibration.dev_attr.attr,
+	&iio_dev_attr_in_capacitance1_calibbias_calibration.dev_attr.attr,
+	&iio_dev_attr_in_voltage0_calibscale_calibration.dev_attr.attr,

+	&iio_const_attr_in_voltage_sampling_frequency_available.dev_attr.attr,
+	&iio_const_attr_in_capacitance_sampling_frequency_available.
+	dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group ad7746_attribute_group = {
+	.attrs = ad7746_attributes,
+};
+
+static int ad7746_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val,
+			    int val2,
+			    long mask)
+{
+	struct ad7746_chip_info *chip = iio_priv(indio_dev);
+	int ret, reg;
+
+	mutex_lock(&indio_dev->mlock);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_CALIBSCALE:
+		if (val != 1) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		val = (val2 * 1024) / 15625;
+
+		switch (chan->type) {
+		case IIO_CAPACITANCE:
+			reg = AD7746_REG_CAP_GAINH;
+			break;
+		case IIO_VOLTAGE:
+			reg = AD7746_REG_VOLT_GAINH;
+			break;
+		default:
+			ret = -EINVAL;
+			goto out;
+		}
+
+		ret = i2c_smbus_write_word_data(chip->client, reg, swab16(val));
If you introduced the swapped version suggested below for read add this
paired write function as well.  Its not as important but makes for
easier to follow code once you know all the registers are reversed.

+		if (ret < 0)
+			goto out;
+
+		ret = 0;
+		break;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		if ((val < 0) | (val > 0xFFFF)) {
+			ret = -EINVAL;
+			goto out;
+		}
+		ret = i2c_smbus_write_word_data(chip->client,
+				AD7746_REG_CAP_OFFH, swab16(val));
+		if (ret < 0)
+			goto out;
+
+		ret = 0;
+		break;
+	case IIO_CHAN_INFO_OFFSET:
+		if ((val < 0) | (val > 43008000)) { /* 21pF */
+			ret = -EINVAL;
+			goto out;
+		}
+
+		/* CAPDAC Scale = 21pF_typ / 127
As below, this isn't standard kernel comment formatting.
+		 * CIN Scale = 8.192pF / 2^24
+		 * Offset Scale = CAPDAC Scale / CIN Scale = 338646
+		 * */
+
+		val /= 338646;
+
+		chip->capdac[chan->channel][chan->differential] = (val > 0 ?
+			AD7746_CAPDAC_DACP(val) | AD7746_CAPDAC_DACEN : 0);
+
+		ret = i2c_smbus_write_byte_data(chip->client,
+			AD7746_REG_CAPDACA,
+			chip->capdac[chan->channel][0]);
+		if (ret < 0)
+			goto out;
+		ret = i2c_smbus_write_byte_data(chip->client,
+			AD7746_REG_CAPDACB,
+			chip->capdac[chan->channel][1]);
+		if (ret < 0)
+			goto out;
+
+		chip->capdac_set = chan->channel;
+
+		ret = 0;
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+out:
+	mutex_unlock(&indio_dev->mlock);
+	return ret;
+}
+
+static int ad7746_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2,
+			   long mask)
+{
+	struct ad7746_chip_info *chip = iio_priv(indio_dev);
+	int ret, delay;
+	u8 regval, reg;
+
+	mutex_lock(&indio_dev->mlock);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+	case IIO_CHAN_INFO_PROCESSED:
+		ret = ad7746_select_channel(indio_dev, chan);
+		if (ret < 0)
+			goto out;
+		delay = ret;
+
+		regval = chip->config | AD7746_CONF_MODE_SINGLE_CONV;
+		ret = i2c_smbus_write_byte_data(chip->client, AD7746_REG_CFG,
+				regval);
+		if (ret < 0)
+			goto out;
+
+		msleep(delay);
+		/* Now read the actual register */
+
+		ret = i2c_smbus_read_i2c_block_data(chip->client,
+			chan->address >> 8, 3, &chip->data.d8[1]);
+
+		if (ret < 0)
+			goto out;
+
+		*val = (be32_to_cpu(chip->data.d32) & 0xFFFFFF) - 0x800000;
+
+		switch (chan->type) {
+		case IIO_TEMP:
Kernel comment format is
/*
* Temp...
*/
+		/* temperature in milli degrees Celsius
+		 * T = ((*val / 2048) - 4096) * 1000
+		 */
+			*val = (*val * 125) / 256;
+			break;
+		case IIO_VOLTAGE:
+			if (chan->channel == 1) /* supply_raw*/
+				*val = *val * 6;
+			break;
+		default:
+			break;
+		}
+
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_CALIBSCALE:
+		switch (chan->type) {
+		case IIO_CAPACITANCE:
+			reg = AD7746_REG_CAP_GAINH;
+			break;
+		case IIO_VOLTAGE:
+			reg = AD7746_REG_VOLT_GAINH;
+			break;
+		default:
+			ret = -EINVAL;
+			goto out;
+		}
+
+		ret = i2c_smbus_read_word_data(chip->client, reg);
+		if (ret < 0)
+			goto out;
+		/* 1 + gain_val / 2^16 */
+		*val = 1;
Interesting.  There is no explicit i2c_smbus_read_word_data for the
swapped case (unliked i2c_smbus_read_word_swapped).  Perhaps one should
be added?  Not sure how common this particular case is.. One to look at?
There are some hidden cases, such as the lm73 driver btw.
Actually a couple of the lm* drivers in hwmon have crazy comparison code
to avoid the fact the data is reversed (worth a look and wince)

+		*val2 = (15625 * swab16(ret)) / 1024;
+
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		ret = i2c_smbus_read_word_data(chip->client,
+					       AD7746_REG_CAP_OFFH);
+		if (ret < 0)
+			goto out;
+		*val = swab16(ret);
+
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_OFFSET:
+		*val = AD7746_CAPDAC_DACP(chip->capdac[chan->channel]
+			[chan->differential]) * 338646;
+
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_CAPACITANCE:
+			/* 8.192pf / 2^24 */
+			*val =  0;
+			*val2 = 488;
+			ret = IIO_VAL_INT_PLUS_NANO;
+			break;
+		case IIO_VOLTAGE:
+			/* 1170mV / 2^23 */
+			*val = 1170;
+			*val2 = 23;
+			ret = IIO_VAL_FRACTIONAL_LOG2;
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+
+		break;
+	default:
+		ret = -EINVAL;
+	}
+out:
+	mutex_unlock(&indio_dev->mlock);
+	return ret;
+}
+
+static const struct iio_info ad7746_info = {
+	.attrs = &ad7746_attribute_group,
+	.read_raw = &ad7746_read_raw,
+	.write_raw = &ad7746_write_raw,
+	.driver_module = THIS_MODULE,
+};
+
+/*
+ * device probe and remove
+ */
+
+static int ad7746_probe(struct i2c_client *client,
+		const struct i2c_device_id *id)
+{
+	struct ad7746_platform_data *pdata = client->dev.platform_data;
+	struct ad7746_chip_info *chip;
+	struct iio_dev *indio_dev;
+	int ret = 0;
This assignement is unnecessary as ret is always assigned in relevant paths
below.
+	unsigned char regval = 0;
I'd be tempted to move the assignement into the single path where it matters
below.
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
+	if (!indio_dev)
+		return -ENOMEM;
+	chip = iio_priv(indio_dev);
+	/* this is only used for device removal purposes */
+	i2c_set_clientdata(client, indio_dev);
+
+	chip->client = client;
+	chip->capdac_set = -1;
+
+	/* Establish that the iio_dev is a child of the i2c device */
+	indio_dev->name = id->name;
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &ad7746_info;
+	indio_dev->channels = ad7746_channels;
+	if (id->driver_data == 7746)
+		indio_dev->num_channels = ARRAY_SIZE(ad7746_channels);
+	else
+		indio_dev->num_channels =  ARRAY_SIZE(ad7746_channels) - 2;
+	indio_dev->num_channels = ARRAY_SIZE(ad7746_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	if (pdata) {
+		if (pdata->exca_en) {
+			if (pdata->exca_inv_en)
+				regval |= AD7746_EXCSETUP_NEXCA;
+			else
+				regval |= AD7746_EXCSETUP_EXCA;
+		}
+
+		if (pdata->excb_en) {
+			if (pdata->excb_inv_en)
+				regval |= AD7746_EXCSETUP_NEXCB;
+			else
+				regval |= AD7746_EXCSETUP_EXCB;
+		}
+
+		regval |= AD7746_EXCSETUP_EXCLVL(pdata->exclvl);
+	} else {
+		dev_warn(&client->dev, "No platform data? using default\n");
+		regval = AD7746_EXCSETUP_EXCA | AD7746_EXCSETUP_EXCB |
+			AD7746_EXCSETUP_EXCLVL(3);
+	}
+
+	ret = i2c_smbus_write_byte_data(chip->client,
+					AD7746_REG_EXC_SETUP, regval);
+	if (ret < 0)
+		return ret;
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		return ret;
+
I'd drop the devinfo that follows.  Doesn't add anything that isn't easy
to check via other means.  Then you can return iio_device_register(...)
directly.

+	dev_info(&client->dev, "%s capacitive sensor registered\n", id->name);
+
+	return 0;
+}
+
+static int ad7746_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 ad7746_id[] = {
+	{ "ad7745", 7745 },
+	{ "ad7746", 7746 },
+	{ "ad7747", 7747 },
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, ad7746_id);
+
+static struct i2c_driver ad7746_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+	},
+	.probe = ad7746_probe,
+	.remove = ad7746_remove,
+	.id_table = ad7746_id,
+};
+module_i2c_driver(ad7746_driver);
+
+MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
+MODULE_DESCRIPTION("Analog Devices AD7746/5/7 capacitive sensor driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/staging/iio/cdc/ad7746.h b/drivers/staging/iio/cdc/ad7746.h
new file mode 100644
index 000000000000..ea8572d1df02
--- /dev/null
+++ b/drivers/staging/iio/cdc/ad7746.h
@@ -0,0 +1,29 @@
+/*
+ * AD7746 capacitive sensor driver supporting AD7745, AD7746 and AD7747
+ *
+ * Copyright 2011 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2.
+ */
+
+#ifndef IIO_CDC_AD7746_H_
+#define IIO_CDC_AD7746_H_
+
+/*
+ * TODO: struct ad7746_platform_data needs to go into include/linux/iio
+ */
+
+#define AD7466_EXCLVL_0		0 /* +-VDD/8 */
+#define AD7466_EXCLVL_1		1 /* +-VDD/4 */
+#define AD7466_EXCLVL_2		2 /* +-VDD * 3/8 */
+#define AD7466_EXCLVL_3		3 /* +-VDD/2 */
+
+struct ad7746_platform_data {
+	unsigned char exclvl;	/*Excitation Voltage Level */
+	bool exca_en;		/* enables EXCA pin as the excitation output */
+	bool exca_inv_en;	/* enables /EXCA pin as the excitation output */
+	bool excb_en;		/* enables EXCB pin as the excitation output */
+	bool excb_inv_en;	/* enables /EXCB pin as the excitation output */
+};
+
+#endif /* IIO_CDC_AD7746_H_ */

Re: [PATCH] Staging: iio: cdc: Remove unused macro

[Shraddha Barke]

On Sun, 20 Sep 2015, Jonathan Cameron wrote:

>
> Hi Shraddha,
>
> To get you started, I've quickly faked up a patch of the driver
> in it's current location to let me 'review' it. Note this was
> a very quick review so I may well have missed lots. Lars
> may have more comments and Michael may hopefully surface as well.
>
> The biggest bit in here is probably the lack of documented
> ABI for the 'calibration' attributes.  Off the top of my
> head I have no clear idea of what they are for.  Then again
> I've never used a CDC and haven't read for this one in years
> which probably doesn't help.
>
> Anyhow, lots of coding style related stuff as well similar to
> what you found in your initial patch.
>
> Hopefully something to get you started.
>

Thanks it helped a lot. You can expect patches from me based on this
soon :)

Thanks,

Shraddha

> Good luck.
>
> Jonathan
>
> p.s. Actually, other than the fact we've gotten tighter on
> coding style stuff etc, this driver is in a pretty good state
> making a good target for finally getting out of staging.
>
> diff --git a/drivers/staging/iio/cdc/ad7746.c b/drivers/staging/iio/cdc/ad7746.c
> new file mode 100644
> index 000000000000..e6e9eaa9eab5
> --- /dev/null
> +++ b/drivers/staging/iio/cdc/ad7746.c
> @@ -0,0 +1,791 @@
> +/*
> + * AD7746 capacitive sensor driver supporting AD7745, AD7746 and AD7747
> + *
> + * Copyright 2011 Analog Devices Inc.
> + *
> + * Licensed under the GPL-2.
> + */
> +
> +#include <linux/interrupt.h>
> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/sysfs.h>
> +#include <linux/i2c.h>
> +#include <linux/delay.h>
> +#include <linux/module.h>
> +#include <linux/stat.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +#include "ad7746.h"
> +
> +/*
> + * AD7746 Register Definition
> + */
> Single line comment probably should have single line comment syntax.
> +
> +#define AD7746_REG_STATUS		0
> +#define AD7746_REG_CAP_DATA_HIGH	1
> +#define AD7746_REG_CAP_DATA_MID		2
> +#define AD7746_REG_CAP_DATA_LOW		3
> +#define AD7746_REG_VT_DATA_HIGH		4
> +#define AD7746_REG_VT_DATA_MID		5
> +#define AD7746_REG_VT_DATA_LOW		6
> +#define AD7746_REG_CAP_SETUP		7
> +#define AD7746_REG_VT_SETUP		8
> +#define AD7746_REG_EXC_SETUP		9
> +#define AD7746_REG_CFG			10
> +#define AD7746_REG_CAPDACA		11
> +#define AD7746_REG_CAPDACB		12
> +#define AD7746_REG_CAP_OFFH		13
> +#define AD7746_REG_CAP_OFFL		14
> +#define AD7746_REG_CAP_GAINH		15
> +#define AD7746_REG_CAP_GAINL		16
> +#define AD7746_REG_VOLT_GAINH		17
> +#define AD7746_REG_VOLT_GAINL		18
> +
> +/* Status Register Bit Designations (AD7746_REG_STATUS) */
> +#define AD7746_STATUS_EXCERR		(1 << 3)
> +#define AD7746_STATUS_RDY		(1 << 2)
> +#define AD7746_STATUS_RDYVT		(1 << 1)
> +#define AD7746_STATUS_RDYCAP		(1 << 0)
> +
> +/* Capacitive Channel Setup Register Bit Designations (AD7746_REG_CAP_SETUP) */
> +#define AD7746_CAPSETUP_CAPEN		(1 << 7)
> +#define AD7746_CAPSETUP_CIN2		(1 << 6) /* AD7746 only */
> +#define AD7746_CAPSETUP_CAPDIFF		(1 << 5)
> +#define AD7746_CAPSETUP_CACHOP		(1 << 0)
> +
> +/* Voltage/Temperature Setup Register Bit Designations (AD7746_REG_VT_SETUP) */
> +#define AD7746_VTSETUP_VTEN		(1 << 7)
> +#define AD7746_VTSETUP_VTMD_INT_TEMP	(0 << 5)
> +#define AD7746_VTSETUP_VTMD_EXT_TEMP	(1 << 5)
> +#define AD7746_VTSETUP_VTMD_VDD_MON	(2 << 5)
> +#define AD7746_VTSETUP_VTMD_EXT_VIN	(3 << 5)
> +#define AD7746_VTSETUP_EXTREF		(1 << 4)
> +#define AD7746_VTSETUP_VTSHORT		(1 << 1)
> +#define AD7746_VTSETUP_VTCHOP		(1 << 0)
> In mixed cases like this, sometimes using the BIT macro
> makes sense, sometimes not. Depends on the use.  So
> I'd epect the bottom 3 to us BIm, but not the ones
> shifted by 5.  That might benefit from a macro though
> to wrap up the shift and make it obvious all those shift by 5 elements
> are actually in the same 2 bit field.
>
> +
> +/* Excitation Setup Register Bit Designations (AD7746_REG_EXC_SETUP) */
> +#define AD7746_EXCSETUP_CLKCTRL		(1 << 7)
> +#define AD7746_EXCSETUP_EXCON		(1 << 6)
> +#define AD7746_EXCSETUP_EXCB		(1 << 5)
> +#define AD7746_EXCSETUP_NEXCB		(1 << 4)
> +#define AD7746_EXCSETUP_EXCA		(1 << 3)
> +#define AD7746_EXCSETUP_NEXCA		(1 << 2)
> This lot are probably a good place to use the BIT macro.
> +#define AD7746_EXCSETUP_EXCLVL(x)	(((x) & 0x3) << 0)
> +
> +/* Config Register Bit Designations (AD7746_REG_CFG) */
> +#define AD7746_CONF_VTFS(x)		((x) << 6)
> +#define AD7746_CONF_CAPFS(x)		((x) << 3)
> +#define AD7746_CONF_MODE_IDLE		(0 << 0)
> +#define AD7746_CONF_MODE_CONT_CONV	(1 << 0)
> +#define AD7746_CONF_MODE_SINGLE_CONV	(2 << 0)
> +#define AD7746_CONF_MODE_PWRDN		(3 << 0)
> +#define AD7746_CONF_MODE_OFFS_CAL	(5 << 0)
> +#define AD7746_CONF_MODE_GAIN_CAL	(6 << 0)
> Hmm. Not sure shifting by 0 is all that informative...
> +
> +/* CAPDAC Register Bit Designations (AD7746_REG_CAPDACx) */
> +#define AD7746_CAPDAC_DACEN		(1 << 7)
> +#define AD7746_CAPDAC_DACP(x)		((x) & 0x7F)
> +
> +/*
> + * struct ad7746_chip_info - chip specific information
> + */
> Single line should probably have single line comment syntax.
> +
> +struct ad7746_chip_info {
> +	struct i2c_client *client;
> +	/*
> +	 * Capacitive channel digital filter setup;
> +	 * conversion time/update rate setup per channel
> +	 */
> +	u8	config;
> +	u8	cap_setup;
> +	u8	vt_setup;
> +	u8	capdac[2][2];
> +	s8	capdac_set;
> +
> +	union {
> +		__be32 d32;
> +		u8 d8[4];
> +	} data ____cacheline_aligned;
> +};
> +
> +enum ad7746_chan {
> +	VIN,
> +	VIN_VDD,
> +	TEMP_INT,
> +	TEMP_EXT,
> +	CIN1,
> +	CIN1_DIFF,
> +	CIN2,
> +	CIN2_DIFF,
> +};
> +
> +static const struct iio_chan_spec ad7746_channels[] = {
> +	[VIN] = {
> +		.type = IIO_VOLTAGE,
> +		.indexed = 1,
> +		.channel = 0,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> +		.address = AD7746_REG_VT_DATA_HIGH << 8 |
> +			AD7746_VTSETUP_VTMD_EXT_VIN,
> +	},
> +	[VIN_VDD] = {
> +		.type = IIO_VOLTAGE,
> +		.indexed = 1,
> +		.channel = 1,
> +		.extend_name = "supply",
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> +		.address = AD7746_REG_VT_DATA_HIGH << 8 |
> +			AD7746_VTSETUP_VTMD_VDD_MON,
> +	},
> +	[TEMP_INT] = {
> +		.type = IIO_TEMP,
> +		.indexed = 1,
> +		.channel = 0,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> +		.address = AD7746_REG_VT_DATA_HIGH << 8 |
> +			AD7746_VTSETUP_VTMD_INT_TEMP,
> These address fields clearly combine multiple elements.  whilst
> concise, this doesn't ease readablility of the code.  See below
> for a suggestion on this.
> +	},
> +	[TEMP_EXT] = {
> +		.type = IIO_TEMP,
> +		.indexed = 1,
> +		.channel = 1,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> +		.address = AD7746_REG_VT_DATA_HIGH << 8 |
> +			AD7746_VTSETUP_VTMD_EXT_TEMP,
> +	},
> +	[CIN1] = {
> +		.type = IIO_CAPACITANCE,
> +		.indexed = 1,
> +		.channel = 0,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +		BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_OFFSET),
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) |
> +		BIT(IIO_CHAN_INFO_SCALE),
> +		.address = AD7746_REG_CAP_DATA_HIGH << 8,
> +	},
> +	[CIN1_DIFF] = {
> +		.type = IIO_CAPACITANCE,
> +		.differential = 1,
> +		.indexed = 1,
> +		.channel = 0,
> +		.channel2 = 2,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +		BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_OFFSET),
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) |
> +		BIT(IIO_CHAN_INFO_SCALE),
> +		.address = AD7746_REG_CAP_DATA_HIGH << 8 |
> +			AD7746_CAPSETUP_CAPDIFF
> +	},
> +	[CIN2] = {
> +		.type = IIO_CAPACITANCE,
> +		.indexed = 1,
> +		.channel = 1,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +		BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_OFFSET),
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) |
> +		BIT(IIO_CHAN_INFO_SCALE),
> +		.address = AD7746_REG_CAP_DATA_HIGH << 8 |
> +			AD7746_CAPSETUP_CIN2,
> +	},
> +	[CIN2_DIFF] = {
> +		.type = IIO_CAPACITANCE,
> +		.differential = 1,
> +		.indexed = 1,
> +		.channel = 1,
> +		.channel2 = 3,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +		BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_OFFSET),
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) |
> +		BIT(IIO_CHAN_INFO_SCALE),
> +		.address = AD7746_REG_CAP_DATA_HIGH << 8 |
> +			AD7746_CAPSETUP_CAPDIFF | AD7746_CAPSETUP_CIN2,
> +	}
> +};
> +
> +/* Values are Update Rate (Hz), Conversion Time (ms) + 1*/
> +static const unsigned char ad7746_vt_filter_rate_table[][2] = {
> +	{50, 20 + 1}, {31, 32 + 1}, {16, 62 + 1}, {8, 122 + 1},
> +};
> +
> +static const unsigned char ad7746_cap_filter_rate_table[][2] = {
> +	{91, 11 + 1}, {84, 12 + 1}, {50, 20 + 1}, {26, 38 + 1},
> +	{16, 62 + 1}, {13, 77 + 1}, {11, 92 + 1}, {9, 110 + 1},
> +};
> +
> +static int ad7746_select_channel(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan)
> +{
> +	struct ad7746_chip_info *chip = iio_priv(indio_dev);
> +	int ret, delay;
> +	u8 vt_setup, cap_setup;
> +
> +	switch (chan->type) {
> +	case IIO_CAPACITANCE:
> This use of part of address strikes me as messy.  I'd have address
> hold a look up index that allows the various things combined in address
> to be held in a nice easy to follow enumerated array of a structures.
> Will give more readable code throughout.
> +		cap_setup = (chan->address & 0xFF) | AD7746_CAPSETUP_CAPEN;
> +		vt_setup = chip->vt_setup & ~AD7746_VTSETUP_VTEN;
> +		delay = ad7746_cap_filter_rate_table[(chip->config >> 3) &
> +			0x7][1];
> +
> +		if (chip->capdac_set != chan->channel) {
> +			ret = i2c_smbus_write_byte_data(chip->client,
> +				AD7746_REG_CAPDACA,
> +				chip->capdac[chan->channel][0]);
> +			if (ret < 0)
> +				return ret;
> +			ret = i2c_smbus_write_byte_data(chip->client,
> +				AD7746_REG_CAPDACB,
> +				chip->capdac[chan->channel][1]);
> +			if (ret < 0)
> +				return ret;
> +
> +			chip->capdac_set = chan->channel;
> +		}
> +		break;
> +	case IIO_VOLTAGE:
> +	case IIO_TEMP:
> +		vt_setup = (chan->address & 0xFF) | AD7746_VTSETUP_VTEN;
> +		cap_setup = chip->cap_setup & ~AD7746_CAPSETUP_CAPEN;
> +		delay = ad7746_cap_filter_rate_table[(chip->config >> 6) &
> +			0x3][1];
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	if (chip->cap_setup != cap_setup) {
> +		ret = i2c_smbus_write_byte_data(chip->client,
> +						AD7746_REG_CAP_SETUP,
> +						cap_setup);
> +		if (ret < 0)
> +			return ret;
> +
> +		chip->cap_setup = cap_setup;
> +	}
> +
> +	if (chip->vt_setup != vt_setup) {
> +		ret = i2c_smbus_write_byte_data(chip->client,
> +						AD7746_REG_VT_SETUP,
> +						vt_setup);
> +		if (ret < 0)
> +			return ret;
> +
> +		chip->vt_setup = vt_setup;
> +	}
> +
> +	return delay;
> +}
> +
> +static inline ssize_t ad7746_start_calib(struct device *dev,
> +					 struct device_attribute *attr,
> +					 const char *buf,
> +					 size_t len,
> +					 u8 regval)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	struct ad7746_chip_info *chip = iio_priv(indio_dev);
> +	bool doit;
> +	int ret, timeout = 10;
> +
> +	ret = strtobool(buf, &doit);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (!doit)
> +		return 0;
> +
> +	mutex_lock(&indio_dev->mlock);
> +	regval |= chip->config;
> +	ret = i2c_smbus_write_byte_data(chip->client, AD7746_REG_CFG, regval);
> +	if (ret < 0) {
> +		mutex_unlock(&indio_dev->mlock);
> +		return ret;
> +	}
> +
> +	do {
> +		msleep(20);
> +		ret = i2c_smbus_read_byte_data(chip->client, AD7746_REG_CFG);
> +		if (ret < 0) {
> +			mutex_unlock(&indio_dev->mlock);
> +			return ret;
> +		}
> +	} while ((ret == regval) && timeout--);
> +
> +	mutex_unlock(&indio_dev->mlock);
> +
> +	return len;
> +}
> +
> +static ssize_t ad7746_start_offset_calib(struct device *dev,
> +					 struct device_attribute *attr,
> +					 const char *buf,
> +					 size_t len)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	int ret = ad7746_select_channel(indio_dev,
> +			      &ad7746_channels[to_iio_dev_attr(attr)->address]);
> +	if (ret < 0)
> +		return ret;
> +
> +	return ad7746_start_calib(dev, attr, buf, len,
> +				  AD7746_CONF_MODE_OFFS_CAL);
> +}
> +
> +static ssize_t ad7746_start_gain_calib(struct device *dev,
> +				       struct device_attribute *attr,
> +				       const char *buf,
> +				       size_t len)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	int ret = ad7746_select_channel(indio_dev,
> +			      &ad7746_channels[to_iio_dev_attr(attr)->address]);
> +	if (ret < 0)
> +		return ret;
> +
> +	return ad7746_start_calib(dev, attr, buf, len,
> +				  AD7746_CONF_MODE_GAIN_CAL);
> +}
> +
> +static IIO_DEVICE_ATTR(in_capacitance0_calibbias_calibration,
> +		       S_IWUSR, NULL, ad7746_start_offset_calib, CIN1);
> +static IIO_DEVICE_ATTR(in_capacitance1_calibbias_calibration,
> +		       S_IWUSR, NULL, ad7746_start_offset_calib, CIN2);
> +static IIO_DEVICE_ATTR(in_capacitance0_calibscale_calibration,
> +		       S_IWUSR, NULL, ad7746_start_gain_calib, CIN1);
> +static IIO_DEVICE_ATTR(in_capacitance1_calibscale_calibration,
> +		       S_IWUSR, NULL, ad7746_start_gain_calib, CIN2);
> +static IIO_DEVICE_ATTR(in_voltage0_calibscale_calibration,
> +		       S_IWUSR, NULL, ad7746_start_gain_calib, VIN);
> +
> +static ssize_t ad7746_show_cap_filter_rate_setup(struct device *dev,
> +		struct device_attribute *attr,
> +		char *buf)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	struct ad7746_chip_info *chip = iio_priv(indio_dev);
> +
> +	return sprintf(buf, "%d\n", ad7746_cap_filter_rate_table[
> +			(chip->config >> 3) & 0x7][0]);
> +}
> +
> +static ssize_t ad7746_store_cap_filter_rate_setup(struct device *dev,
> +		struct device_attribute *attr,
> +		const char *buf,
> +		size_t len)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	struct ad7746_chip_info *chip = iio_priv(indio_dev);
> +	u8 data;
> +	int ret, i;
> +
> +	ret = kstrtou8(buf, 10, &data);
> +	if (ret < 0)
> +		return ret;
> +
> +	for (i = 0; i < ARRAY_SIZE(ad7746_cap_filter_rate_table); i++)
> +		if (data >= ad7746_cap_filter_rate_table[i][0])
> +			break;
> +
> +	if (i >= ARRAY_SIZE(ad7746_cap_filter_rate_table))
> +		i = ARRAY_SIZE(ad7746_cap_filter_rate_table) - 1;
> +
> +	mutex_lock(&indio_dev->mlock);
> +	chip->config &= ~AD7746_CONF_CAPFS(0x7);
> +	chip->config |= AD7746_CONF_CAPFS(i);
> +	mutex_unlock(&indio_dev->mlock);
> +
> +	return len;
> +}
> +
> +static ssize_t ad7746_show_vt_filter_rate_setup(struct device *dev,
> +		struct device_attribute *attr,
> +		char *buf)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	struct ad7746_chip_info *chip = iio_priv(indio_dev);
> +
> +	return sprintf(buf, "%d\n", ad7746_vt_filter_rate_table[
> +			(chip->config >> 6) & 0x3][0]);
> +}
> +
> +static ssize_t ad7746_store_vt_filter_rate_setup(struct device *dev,
> +		struct device_attribute *attr,
> +		const char *buf,
> +		size_t len)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	struct ad7746_chip_info *chip = iio_priv(indio_dev);
> +	u8 data;
> +	int ret, i;
> +
> +	ret = kstrtou8(buf, 10, &data);
> +	if (ret < 0)
> +		return ret;
> +
> +	for (i = 0; i < ARRAY_SIZE(ad7746_vt_filter_rate_table); i++)
> +		if (data >= ad7746_vt_filter_rate_table[i][0])
> +			break;
> +
> +	if (i >= ARRAY_SIZE(ad7746_vt_filter_rate_table))
> +		i = ARRAY_SIZE(ad7746_vt_filter_rate_table) - 1;
> +
> +	mutex_lock(&indio_dev->mlock);
> +	chip->config &= ~AD7746_CONF_VTFS(0x3);
> +	chip->config |= AD7746_CONF_VTFS(i);
> +	mutex_unlock(&indio_dev->mlock);
> +
> +	return len;
> +}
> +
> +static IIO_DEVICE_ATTR(in_capacitance_sampling_frequency,
> +		       S_IRUGO | S_IWUSR, ad7746_show_cap_filter_rate_setup,
> +			ad7746_store_cap_filter_rate_setup, 0);
> +
> +static IIO_DEVICE_ATTR(in_voltage_sampling_frequency,
> +		       S_IRUGO | S_IWUSR, ad7746_show_vt_filter_rate_setup,
> +		       ad7746_store_vt_filter_rate_setup, 0);
> +
> +static IIO_CONST_ATTR(in_voltage_sampling_frequency_available, "50 31 16 8");
> +static IIO_CONST_ATTR(in_capacitance_sampling_frequency_available,
> +		       "91 84 50 26 16 13 11 9");
> +
> +static struct attribute *ad7746_attributes[] = {
> +	&iio_dev_attr_in_capacitance_sampling_frequency.dev_attr.attr,
> +	&iio_dev_attr_in_voltage_sampling_frequency.dev_attr.attr,
> Can now be done as a standard info_mask element - in this case
> these would be shared_by_type.
>
> +	&iio_dev_attr_in_capacitance0_calibbias_calibration.dev_attr.attr,
> These need docummenting / understanding which I don't have right now!
> +	&iio_dev_attr_in_capacitance0_calibscale_calibration.dev_attr.attr,
> +	&iio_dev_attr_in_capacitance1_calibscale_calibration.dev_attr.attr,
> +	&iio_dev_attr_in_capacitance1_calibbias_calibration.dev_attr.attr,
> +	&iio_dev_attr_in_voltage0_calibscale_calibration.dev_attr.attr,
>
> +	&iio_const_attr_in_voltage_sampling_frequency_available.dev_attr.attr,
> +	&iio_const_attr_in_capacitance_sampling_frequency_available.
> +	dev_attr.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group ad7746_attribute_group = {
> +	.attrs = ad7746_attributes,
> +};
> +
> +static int ad7746_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int val,
> +			    int val2,
> +			    long mask)
> +{
> +	struct ad7746_chip_info *chip = iio_priv(indio_dev);
> +	int ret, reg;
> +
> +	mutex_lock(&indio_dev->mlock);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_CALIBSCALE:
> +		if (val != 1) {
> +			ret = -EINVAL;
> +			goto out;
> +		}
> +
> +		val = (val2 * 1024) / 15625;
> +
> +		switch (chan->type) {
> +		case IIO_CAPACITANCE:
> +			reg = AD7746_REG_CAP_GAINH;
> +			break;
> +		case IIO_VOLTAGE:
> +			reg = AD7746_REG_VOLT_GAINH;
> +			break;
> +		default:
> +			ret = -EINVAL;
> +			goto out;
> +		}
> +
> +		ret = i2c_smbus_write_word_data(chip->client, reg, swab16(val));
> If you introduced the swapped version suggested below for read add this
> paired write function as well.  Its not as important but makes for
> easier to follow code once you know all the registers are reversed.
>
> +		if (ret < 0)
> +			goto out;
> +
> +		ret = 0;
> +		break;
> +	case IIO_CHAN_INFO_CALIBBIAS:
> +		if ((val < 0) | (val > 0xFFFF)) {
> +			ret = -EINVAL;
> +			goto out;
> +		}
> +		ret = i2c_smbus_write_word_data(chip->client,
> +				AD7746_REG_CAP_OFFH, swab16(val));
> +		if (ret < 0)
> +			goto out;
> +
> +		ret = 0;
> +		break;
> +	case IIO_CHAN_INFO_OFFSET:
> +		if ((val < 0) | (val > 43008000)) { /* 21pF */
> +			ret = -EINVAL;
> +			goto out;
> +		}
> +
> +		/* CAPDAC Scale = 21pF_typ / 127
> As below, this isn't standard kernel comment formatting.
> +		 * CIN Scale = 8.192pF / 2^24
> +		 * Offset Scale = CAPDAC Scale / CIN Scale = 338646
> +		 * */
> +
> +		val /= 338646;
> +
> +		chip->capdac[chan->channel][chan->differential] = (val > 0 ?
> +			AD7746_CAPDAC_DACP(val) | AD7746_CAPDAC_DACEN : 0);
> +
> +		ret = i2c_smbus_write_byte_data(chip->client,
> +			AD7746_REG_CAPDACA,
> +			chip->capdac[chan->channel][0]);
> +		if (ret < 0)
> +			goto out;
> +		ret = i2c_smbus_write_byte_data(chip->client,
> +			AD7746_REG_CAPDACB,
> +			chip->capdac[chan->channel][1]);
> +		if (ret < 0)
> +			goto out;
> +
> +		chip->capdac_set = chan->channel;
> +
> +		ret = 0;
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +out:
> +	mutex_unlock(&indio_dev->mlock);
> +	return ret;
> +}
> +
> +static int ad7746_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val, int *val2,
> +			   long mask)
> +{
> +	struct ad7746_chip_info *chip = iio_priv(indio_dev);
> +	int ret, delay;
> +	u8 regval, reg;
> +
> +	mutex_lock(&indio_dev->mlock);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +	case IIO_CHAN_INFO_PROCESSED:
> +		ret = ad7746_select_channel(indio_dev, chan);
> +		if (ret < 0)
> +			goto out;
> +		delay = ret;
> +
> +		regval = chip->config | AD7746_CONF_MODE_SINGLE_CONV;
> +		ret = i2c_smbus_write_byte_data(chip->client, AD7746_REG_CFG,
> +				regval);
> +		if (ret < 0)
> +			goto out;
> +
> +		msleep(delay);
> +		/* Now read the actual register */
> +
> +		ret = i2c_smbus_read_i2c_block_data(chip->client,
> +			chan->address >> 8, 3, &chip->data.d8[1]);
> +
> +		if (ret < 0)
> +			goto out;
> +
> +		*val = (be32_to_cpu(chip->data.d32) & 0xFFFFFF) - 0x800000;
> +
> +		switch (chan->type) {
> +		case IIO_TEMP:
> Kernel comment format is
> /*
> * Temp...
> */
> +		/* temperature in milli degrees Celsius
> +		 * T = ((*val / 2048) - 4096) * 1000
> +		 */
> +			*val = (*val * 125) / 256;
> +			break;
> +		case IIO_VOLTAGE:
> +			if (chan->channel == 1) /* supply_raw*/
> +				*val = *val * 6;
> +			break;
> +		default:
> +			break;
> +		}
> +
> +		ret = IIO_VAL_INT;
> +		break;
> +	case IIO_CHAN_INFO_CALIBSCALE:
> +		switch (chan->type) {
> +		case IIO_CAPACITANCE:
> +			reg = AD7746_REG_CAP_GAINH;
> +			break;
> +		case IIO_VOLTAGE:
> +			reg = AD7746_REG_VOLT_GAINH;
> +			break;
> +		default:
> +			ret = -EINVAL;
> +			goto out;
> +		}
> +
> +		ret = i2c_smbus_read_word_data(chip->client, reg);
> +		if (ret < 0)
> +			goto out;
> +		/* 1 + gain_val / 2^16 */
> +		*val = 1;
> Interesting.  There is no explicit i2c_smbus_read_word_data for the
> swapped case (unliked i2c_smbus_read_word_swapped).  Perhaps one should
> be added?  Not sure how common this particular case is.. One to look at?
> There are some hidden cases, such as the lm73 driver btw.
> Actually a couple of the lm* drivers in hwmon have crazy comparison code
> to avoid the fact the data is reversed (worth a look and wince)
>
> +		*val2 = (15625 * swab16(ret)) / 1024;
> +
> +		ret = IIO_VAL_INT_PLUS_MICRO;
> +		break;
> +	case IIO_CHAN_INFO_CALIBBIAS:
> +		ret = i2c_smbus_read_word_data(chip->client,
> +					       AD7746_REG_CAP_OFFH);
> +		if (ret < 0)
> +			goto out;
> +		*val = swab16(ret);
> +
> +		ret = IIO_VAL_INT;
> +		break;
> +	case IIO_CHAN_INFO_OFFSET:
> +		*val = AD7746_CAPDAC_DACP(chip->capdac[chan->channel]
> +			[chan->differential]) * 338646;
> +
> +		ret = IIO_VAL_INT;
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_CAPACITANCE:
> +			/* 8.192pf / 2^24 */
> +			*val =  0;
> +			*val2 = 488;
> +			ret = IIO_VAL_INT_PLUS_NANO;
> +			break;
> +		case IIO_VOLTAGE:
> +			/* 1170mV / 2^23 */
> +			*val = 1170;
> +			*val2 = 23;
> +			ret = IIO_VAL_FRACTIONAL_LOG2;
> +			break;
> +		default:
> +			ret = -EINVAL;
> +			break;
> +		}
> +
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +out:
> +	mutex_unlock(&indio_dev->mlock);
> +	return ret;
> +}
> +
> +static const struct iio_info ad7746_info = {
> +	.attrs = &ad7746_attribute_group,
> +	.read_raw = &ad7746_read_raw,
> +	.write_raw = &ad7746_write_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +/*
> + * device probe and remove
> + */
> +
> +static int ad7746_probe(struct i2c_client *client,
> +		const struct i2c_device_id *id)
> +{
> +	struct ad7746_platform_data *pdata = client->dev.platform_data;
> +	struct ad7746_chip_info *chip;
> +	struct iio_dev *indio_dev;
> +	int ret = 0;
> This assignement is unnecessary as ret is always assigned in relevant paths
> below.
> +	unsigned char regval = 0;
> I'd be tempted to move the assignement into the single path where it matters
> below.
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +	chip = iio_priv(indio_dev);
> +	/* this is only used for device removal purposes */
> +	i2c_set_clientdata(client, indio_dev);
> +
> +	chip->client = client;
> +	chip->capdac_set = -1;
> +
> +	/* Establish that the iio_dev is a child of the i2c device */
> +	indio_dev->name = id->name;
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->info = &ad7746_info;
> +	indio_dev->channels = ad7746_channels;
> +	if (id->driver_data == 7746)
> +		indio_dev->num_channels = ARRAY_SIZE(ad7746_channels);
> +	else
> +		indio_dev->num_channels =  ARRAY_SIZE(ad7746_channels) - 2;
> +	indio_dev->num_channels = ARRAY_SIZE(ad7746_channels);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	if (pdata) {
> +		if (pdata->exca_en) {
> +			if (pdata->exca_inv_en)
> +				regval |= AD7746_EXCSETUP_NEXCA;
> +			else
> +				regval |= AD7746_EXCSETUP_EXCA;
> +		}
> +
> +		if (pdata->excb_en) {
> +			if (pdata->excb_inv_en)
> +				regval |= AD7746_EXCSETUP_NEXCB;
> +			else
> +				regval |= AD7746_EXCSETUP_EXCB;
> +		}
> +
> +		regval |= AD7746_EXCSETUP_EXCLVL(pdata->exclvl);
> +	} else {
> +		dev_warn(&client->dev, "No platform data? using default\n");
> +		regval = AD7746_EXCSETUP_EXCA | AD7746_EXCSETUP_EXCB |
> +			AD7746_EXCSETUP_EXCLVL(3);
> +	}
> +
> +	ret = i2c_smbus_write_byte_data(chip->client,
> +					AD7746_REG_EXC_SETUP, regval);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret)
> +		return ret;
> +
> I'd drop the devinfo that follows.  Doesn't add anything that isn't easy
> to check via other means.  Then you can return iio_device_register(...)
> directly.
>
> +	dev_info(&client->dev, "%s capacitive sensor registered\n", id->name);
> +
> +	return 0;
> +}
> +
> +static int ad7746_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 ad7746_id[] = {
> +	{ "ad7745", 7745 },
> +	{ "ad7746", 7746 },
> +	{ "ad7747", 7747 },
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, ad7746_id);
> +
> +static struct i2c_driver ad7746_driver = {
> +	.driver = {
> +		.name = KBUILD_MODNAME,
> +	},
> +	.probe = ad7746_probe,
> +	.remove = ad7746_remove,
> +	.id_table = ad7746_id,
> +};
> +module_i2c_driver(ad7746_driver);
> +
> +MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
> +MODULE_DESCRIPTION("Analog Devices AD7746/5/7 capacitive sensor driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/staging/iio/cdc/ad7746.h b/drivers/staging/iio/cdc/ad7746.h
> new file mode 100644
> index 000000000000..ea8572d1df02
> --- /dev/null
> +++ b/drivers/staging/iio/cdc/ad7746.h
> @@ -0,0 +1,29 @@
> +/*
> + * AD7746 capacitive sensor driver supporting AD7745, AD7746 and AD7747
> + *
> + * Copyright 2011 Analog Devices Inc.
> + *
> + * Licensed under the GPL-2.
> + */
> +
> +#ifndef IIO_CDC_AD7746_H_
> +#define IIO_CDC_AD7746_H_
> +
> +/*
> + * TODO: struct ad7746_platform_data needs to go into include/linux/iio
> + */
> +
> +#define AD7466_EXCLVL_0		0 /* +-VDD/8 */
> +#define AD7466_EXCLVL_1		1 /* +-VDD/4 */
> +#define AD7466_EXCLVL_2		2 /* +-VDD * 3/8 */
> +#define AD7466_EXCLVL_3		3 /* +-VDD/2 */
> +
> +struct ad7746_platform_data {
> +	unsigned char exclvl;	/*Excitation Voltage Level */
> +	bool exca_en;		/* enables EXCA pin as the excitation output */
> +	bool exca_inv_en;	/* enables /EXCA pin as the excitation output */
> +	bool excb_en;		/* enables EXCB pin as the excitation output */
> +	bool excb_inv_en;	/* enables /EXCB pin as the excitation output */
> +};
> +
> +#endif /* IIO_CDC_AD7746_H_ */
>
>
>