Re: [PATCH v2] Adds support for the Texas Instruments ADS1110 adc.

[Lars-Peter Clausen <lars@metafoo.de>]

On 12/21/2011 12:17 PM, Pirmin Duss wrote:
> This is the second iteration of the patch to add the Texas Instruments
> ADS1110 adc driver.
> 
> Signed-off-by: Pirmin Duss (Flytec) <pirmin.duss@flytec.ch>

Looks mostly good to me, except a few minor issues (mostly code style).

> ---
>  drivers/staging/iio/adc/Kconfig   |   10 +
>  drivers/staging/iio/adc/Makefile  |    1 +
>  drivers/staging/iio/adc/ads1110.c |  397 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 408 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/staging/iio/adc/ads1110.c
> 
> diff --git a/drivers/staging/iio/adc/Kconfig b/drivers/staging/iio/adc/Kconfig
> index d9decea..ab516dd 100644
> --- a/drivers/staging/iio/adc/Kconfig
> +++ b/drivers/staging/iio/adc/Kconfig
> @@ -145,6 +145,16 @@ config AD7192
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called ad7192.
>  
> +config ADS1110
> +	tristate "Texas Instruments ADS1110 Analog Digital Converter driver"
> +	depends on I2C
> +	help
> +		Say yes here to build support for Texas Instruments ads1110 ADC.
> +		Provides direct access via sysfs.
> +
> +		To compile this driver as a module, choose M here: the
> +		module will be called ads1110.
> +
>  config ADT7310
>  	tristate "Analog Devices ADT7310 temperature sensor driver"
>  	depends on SPI
> diff --git a/drivers/staging/iio/adc/Makefile b/drivers/staging/iio/adc/Makefile
> index ceee7f3..5551e03 100644
> --- a/drivers/staging/iio/adc/Makefile
> +++ b/drivers/staging/iio/adc/Makefile
> @@ -34,6 +34,7 @@ obj-$(CONFIG_AD7780) += ad7780.o
>  obj-$(CONFIG_AD7793) += ad7793.o
>  obj-$(CONFIG_AD7816) += ad7816.o
>  obj-$(CONFIG_AD7192) += ad7192.o
> +obj-$(CONFIG_ADS1110) += ads1110.o
>  obj-$(CONFIG_ADT7310) += adt7310.o
>  obj-$(CONFIG_ADT7410) += adt7410.o
>  obj-$(CONFIG_AD7280) += ad7280a.o
> diff --git a/drivers/staging/iio/adc/ads1110.c b/drivers/staging/iio/adc/ads1110.c
> new file mode 100644
> index 0000000..ad0d386
> --- /dev/null
> +++ b/drivers/staging/iio/adc/ads1110.c
> @@ -0,0 +1,397 @@
> +/*
> + * Driver for Texas Instruments ads1110 ADC.
> + *
> + * Datashhet con be found on: http://www.ti.com/lit/ds/symlink/ads1110.pdf
> + *
> + * Copyright 2011 Flytec AG.
> + *
> + * Licensed under the GPL-2 or later.
> + */
> +
> +#include <linux/interrupt.h>
Not used

> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/sysfs.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/err.h>
> +
> +#include "../iio.h"
> +#include "../sysfs.h"
> +
> +/*
> + * ADS1110 definitions
> + */
> +
> +#define ADS1110_CYC_MASK		0x0C
> +#define ADS1110_CYC_SHIFT		2
> +#define ADS1110_CYC_TCONF_15		3
> +#define ADS1110_CYC_TCONF_30		2
> +#define ADS1110_CYC_TCONF_60		1
> +#define ADS1110_CYC_TCONF_240		0
> +
> +#define ADS1110_PGA_MASK		0x03
> +#define ADS1110_PGA_CLEAR   		0x9C
> +#define ADS1110_PGA_1			0
> +#define ADS1110_PGA_2			1
> +#define ADS1110_PGA_4			2
> +#define ADS1110_PGA_8			3
> +
> +#define ADS1110_MAX_CONV_MODE		2
> +#define ADS1110_MAX_DATA_RATE		4
> +#define ADS1110_MAX_PGA		4
> +
> +/*
> + * struct ads1110_chip_info  - chip specifig information
> + */
> +
> +struct ads1110_chip_info {
> +	struct i2c_client	*client;
> +};
> +
> +static const unsigned int ads1110_frequencies[] = {
> +	[ADS1110_CYC_TCONF_240] = 240,
> +	[ADS1110_CYC_TCONF_60] = 60,
> +	[ADS1110_CYC_TCONF_30] = 30,
> +	[ADS1110_CYC_TCONF_15] = 15,
> +};
> +
> +struct ads1110_pga {
> +	char *name;
> +	u8 reg_cfg;
> +};
> +
> +static struct ads1110_pga
> +ads1110_pga_table[ADS1110_MAX_PGA] = {
> +	{ "gain-1",  ADS1110_PGA_1 },
> +	{ "gain-2",  ADS1110_PGA_2 },
> +	{ "gain-4",  ADS1110_PGA_4 },
> +	{ "gain-8",  ADS1110_PGA_8 },
> +};
> +
> +/*
> + * channel specifications
> + */
> +
> +static const struct iio_chan_spec ads1110_channels[] = {
> +	IIO_CHAN(IIO_VOLTAGE, 0, 1, 0, NULL, 0, 0, 0, 0, 0, 
> +		IIO_ST('s', 16, 16, 0), 0),
> +};
> +
> +/*
> + * cummunication functions for i2c
> + */
> +
> +static int ads1110_i2c_read_config(struct ads1110_chip_info *chip, u8 *data)
> +{
> +	struct i2c_client *client = chip->client;
> +	int ret = 0;
> +	u8 tmp[3];		/* read three bytes ; first two are data third is the config */
> +
> +	ret = i2c_master_recv(client, tmp, 3);
> +	if (ret < 3) {
> +		dev_err(&client->dev, "I2C read error\n");
> +		return ret;
> +	}
> +
> +	*data = tmp[2];
> +
> +	return ret;
> +}
> +
> +static int ads1110_i2c_read_data(struct ads1110_chip_info *chip, int *data)
> +{
> +	struct i2c_client *client = chip->client;
> +	int ret = 0;
> +	u8 tmp[3];		/* read three bytes ; first two are data third is the config */

I just had a quick look at the data-sheet because I expected that it should be
possible to only read the two data bytes and the data-sheet confirms this:

"It is not required to read the configuration register byte. It
is permissible to read fewer than three bytes during a read
operation."

> +
> +	ret = i2c_master_recv(client, tmp, 3);
> +	if (ret < 3) {
> +		dev_err(&client->dev, "I2C read error\n");
> +		return ret;
> +	}
> +
> +	*data = (int)(tmp[0] << 8) + tmp[1];

Use be16_to_cpu and __be16 as the type for tmp.

> +
> +	return ret;
> +}
> +
> +
> +static int ads1110_i2c_write_config(struct ads1110_chip_info *chip, u8 data)
> +{
> +	struct i2c_client *client = chip->client;
> +	int ret = 0;
> +
> +	ret = i2c_master_send(client, &data, 1);        /* there is only one register to write to. */
> +	if (ret < 0)
> +		dev_err(&client->dev, "I2C write error\n");
> +
> +	return ret;
> +}
> +
> +/*
> + * setter- / getter functions for the sysfs nodes.
> + */
> +
> +static ssize_t ads1110_read_frequency(struct device *dev,
> +		struct device_attribute *attr,
> +		char *buf)
> +{
> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
> +	struct ads1110_chip_info *st = iio_priv(indio_dev);
> +	u8 cfg;
> +
> +	ads1110_i2c_read_config(st, &cfg);

It probably makes sense to cache the config register in software, unless you
expect it to change without software interaction.

> +	cfg = ((cfg & ADS1110_CYC_MASK) >> ADS1110_CYC_SHIFT);
> +
> +	return sprintf(buf, "%d\n", ads1110_frequencies[cfg]);
> +}
> +
> +static ssize_t ads1110_write_frequency(struct device *dev,
> +		struct device_attribute *attr,
> +		const char *buf,
> +		size_t len)
> +{
> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
> +	struct ads1110_chip_info *st = iio_priv(indio_dev);
> +	unsigned long lval;
> +	int ret, i;
> +	u8 cfg;
> +
> +	ads1110_i2c_read_config(st, &cfg);
> +
> +	ret = kstrtoul(buf, 10, &lval);
> +	if (ret)
> +		return ret;
> +
> +	if (lval < 15 || lval > 240) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	for (i = 0; i < ARRAY_SIZE(ads1110_frequencies); i++)
> +		if (lval == ads1110_frequencies[i])
> +			break;
> +
> +	if (i == ARRAY_SIZE(ads1110_frequencies)) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	cfg &= ~ADS1110_CYC_MASK;               /* erase old datarate */
> +	cfg |= (i << ADS1110_CYC_SHIFT);
> +
> +	ads1110_i2c_write_config(st, cfg);

This is a bit racy, since it is possible that for example both gain and
frequency are updated concurrently. The read-modify-write operation should be
done atomicly. E.g. by holding the iio_dev mlock mutex.

> +
> +out:
> +	return ret ? ret : len;
> +}
> +
> +static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO,
> +		ads1110_read_frequency,
> +		ads1110_write_frequency);
> +
> +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("240 60 30 15");
> +
> +static ssize_t ads1110_show_gains(struct device *dev,
> +		struct device_attribute *attr,
> +		char *buf)
> +{
> +	int i;
> +	int len = 0;
> +
> +	for (i = 0; i < ADS1110_MAX_PGA; i++)
> +		len += sprintf(buf + len, "%s\n", ads1110_pga_table[i].name);
> +
> +	return len;
> +}
> +
> +static IIO_DEVICE_ATTR(gains_available,
> +		S_IRUGO,
> +		ads1110_show_gains, NULL, 0);
> +
> +static ssize_t ads1110_show_gain(struct device *dev,
> +		struct device_attribute *attr,
> +		char *buf)
> +{
> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
> +	struct ads1110_chip_info *st = iio_priv(indio_dev);
> +	u8 cfg;
> +
> +	ads1110_i2c_read_config(st, &cfg);
> +	cfg = (cfg & ADS1110_PGA_MASK);
> +
> +	return sprintf(buf, "%s\n", ads1110_pga_table[cfg].name);
> +}
> +
> +static ssize_t ads1110_store_gain(struct device *dev,
> +		struct device_attribute *attr,
> +		const char *buf,
> +		size_t len)
> +{
> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
> +	struct ads1110_chip_info *st = iio_priv(indio_dev);
> +	u8 cfg;
> +	int i;
> +
> +	for (i = 0; i < ADS1110_MAX_PGA; i++) {
> +		if (strncmp(buf, ads1110_pga_table[i].name,
> +			strlen(ads1110_pga_table[i].name)) == 0) {
> +			ads1110_i2c_read_config(st, &cfg);
> +			cfg &= ADS1110_PGA_CLEAR;		/* clear old value */
> +			cfg |= ads1110_pga_table[i].reg_cfg;
> +			ads1110_i2c_write_config(st, cfg);
> +			return len;
> +		}
> +	}
> +
> +	dev_err(dev, "not supported gain\n");
> +
> +	return -EINVAL;
> +}
> +
> +static IIO_DEVICE_ATTR(gain,
> +		S_IRUGO | S_IWUSR,
> +		ads1110_show_gain, ads1110_store_gain, 0);

Use the scale attribute for gain. You can easily do this by using channel spec.

> +
> +static int ads1110_read_raw(struct iio_dev *indio_dev,
> +		struct iio_chan_spec const *chan,
> +		int *val,
> +		int *val2,
> +		long mask)
> +{
> +	struct ads1110_chip_info *st = iio_priv(indio_dev);
> +	int ret, data;
> +
> +	ret = ads1110_i2c_read_data(st, &data);
> +	if (ret!=3)

missing spaces

> +		return -EIO;
> +
> +	*val = data;
> +	*val2 = 0;
> +
> +	return IIO_VAL_INT;
> +}
> +
> +/*
> + * attributes for sysfs
> + */
> +
> +static struct attribute *ads1110_attributes[] = {
> +	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
> +	&iio_dev_attr_sampling_frequency.dev_attr.attr,
> +	&iio_dev_attr_gains_available.dev_attr.attr,
> +	&iio_dev_attr_gain.dev_attr.attr,
> +	NULL,
> +};
> + 
> +static const struct attribute_group ads1110_attribute_group = {
> +	.attrs = ads1110_attributes,
> +};
> +
> +static const struct iio_info ads1110_info = {
> +	.attrs = &ads1110_attribute_group,
> +	.event_attrs = NULL,
> +	.read_raw = &ads1110_read_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +/*
> + * device probe and remove
> + */
> +
> +static int __devinit ads1110_probe(struct i2c_client *client,
> +		const struct i2c_device_id *id)
> +{
> +	int ret = 0, regdone = 0;
> +	struct ads1110_chip_info *chip;
> +	struct iio_dev *indio_dev;
> +
> +	indio_dev= iio_allocate_device(sizeof(*chip));

missing space before the =

> +	if (indio_dev == NULL) {
> +		ret = -ENOMEM;
> +		goto error_ret;
> +	}
> +	chip = iio_priv(indio_dev);
> +
> +	/* this is only used for device removal purposes  */
> +	i2c_set_clientdata(client, indio_dev);
> +
> +	chip->client = client;
> +
> +	/* 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 = &ads1110_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = ads1110_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(ads1110_channels);
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret)
> +		goto error_free_dev;
> +	regdone = 1;
> +
> +	dev_err(&client->dev, "%s ADC registered.\n", id->name);
> +
> +	return 0;
> +
> +error_free_dev:
> +	if (regdone)

 regdone will never be true here, so it can probably be removed altogether.

> +		iio_device_unregister(indio_dev);
> +	iio_free_device(indio_dev);
> +	kfree(chip);
> +error_ret:
> +	return ret;
> +}
> +
> +static int __devexit ads1110_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +
> +	iio_device_unregister(indio_dev);
> +	iio_free_device(indio_dev);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id ads1110_id[] = {
> +	{ "ads1110-ed0", 0x48 },
> +	{ "ads1110-ed1", 0x49 },
> +	{ "ads1110-ed2", 0x50 },
> +	{ "ads1110-ed3", 0x51 },
> +	{ "ads1110-ed4", 0x52 },
> +	{ "ads1110-ed5", 0x53 },
> +	{ "ads1110-ed6", 0x54 },
> +	{ "ads1110-ed7", 0x55 },
> +	{}
> +};
> +

Remove the empty line above.

> +MODULE_DEVICE_TABLE(i2c, ads1110_id);
> +
> +static struct i2c_driver ads1110_driver = {
> +	.driver = {
> +		.name = "ads1110",
> +	},
> +	.probe = ads1110_probe,
> +	.remove = __devexit_p(ads1110_remove),
> +	.id_table = ads1110_id,
> +};
> +
> +static __init int ads1110_init(void)

The prefered form is "int __init" instead of "__init int", but that's really
just nitpicking.

> +{
> +	return i2c_add_driver(&ads1110_driver);
> +}
> +
> +static __exit void ads1110_exit(void)

Same here.

> +{
> +	i2c_del_driver(&ads1110_driver);
> +}
> +
> +MODULE_AUTHOR("Duss Pirmin <pirmin.duss@flytec.ch>");
> +MODULE_DESCRIPTION("Texas Instruments ads1110 adc driver");
> +MODULE_LICENSE("GPL v2");
> +
> +module_init(ads1110_init);
> +module_exit(ads1110_exit);