[PATCH v4] hwmon: Add support for Texas Instruments ADS1015

Grant Likely grant.likely at secretlab.ca
Fri Mar 4 04:50:50 EST 2011


[cc'ing Kay and Greg regarding sysfs stuff; please make sure my
comments are accurate.  :-) ]
On Thu, Mar 03, 2011 at 08:45:43AM +0100, Dirk Eibach wrote:
> Signed-off-by: Dirk Eibach <eibach at gdsys.de>

Patch is missing description.

> ---
> Changes since v1:
> - fixed/extended Documentation
> - removed unused register definitions
> - hardcoded PGA fullscale table size
> - made sure patch applies against v2.6.38-rc4
> - reordered functions to avoid forward declaration
> - results from i2c_smbus_read_word_data() are handled correctly
> - moved locking into ads1015_read_value()
> - removed unnecessray clearing of bit
> - proper error handling in ads1015_read_value()
> - use DIV_ROUND_CLOSEST for scaling result
> - removed detect()
> 
> Changes since v2:
> - removed *all* leftovers from detect()
> - fixed return with mutex held
> - made sysfs representation configurable
>   (hope this will be the reference implementation for generations to come ;)
> 
> Changes since v3:
> - included linux/of.h
> - remove linux/types.h from header file
> - sysfs is now configured with a bitmask
> - assume big-endian of-properties

I recommend putting the revision history *above* the '---' trim line.
It turns out to be useful to have the revision history in the commit
text that actually gets merged into mainline.

> 
> Documentation/hwmon/ads1015 |   67 ++++++++++
>  drivers/hwmon/Kconfig       |   10 ++
>  drivers/hwmon/Makefile      |    1 +
>  drivers/hwmon/ads1015.c     |  283 +++++++++++++++++++++++++++++++++++++++++++
>  include/linux/i2c/ads1015.h |   28 +++++

You can merge the Documentation/devicetree/bindings documentation
change into this patch.  No point in merging it separately.

>  5 files changed, 389 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/hwmon/ads1015
>  create mode 100644 drivers/hwmon/ads1015.c
>  create mode 100644 include/linux/i2c/ads1015.h
> 
> diff --git a/Documentation/hwmon/ads1015 b/Documentation/hwmon/ads1015
> new file mode 100644
> index 0000000..56ee797
> --- /dev/null
> +++ b/Documentation/hwmon/ads1015
> @@ -0,0 +1,67 @@
> +Kernel driver ads1015
> +=====================
> +
> +Supported chips:
> +  * Texas Instruments ADS1015
> +    Prefix: 'ads1015'
> +    Datasheet: Publicly available at the Texas Instruments website :
> +               http://focus.ti.com/lit/ds/symlink/ads1015.pdf
> +
> +Authors:
> +        Dirk Eibach, Guntermann & Drunck GmbH <eibach at gdsys.de>
> +
> +Description
> +-----------
> +
> +This driver implements support for the Texas Instruments ADS1015.
> +
> +This device is a 12-bit A-D converter with 4 inputs.
> +
> +The inputs can be used single ended or in certain differential combinations.
> +
> +The inputs can be exported to 8 sysfs input files in0_input - in7_input:
> +in0: Voltage over AIN0 and AIN1.
> +in1: Voltage over AIN0 and AIN3.
> +in2: Voltage over AIN1 and AIN3.
> +in3: Voltage over AIN2 and AIN3.
> +in4: Voltage over AIN0 and GND.
> +in5: Voltage over AIN1 and GND.
> +in6: Voltage over AIN2 and GND.
> +in7: Voltage over AIN3 and GND.
> +
> +Which inputs are exported can be configured using platform data or devicetree.
> +
> +By default all inputs are exported.
> +
> +Platform Data
> +-------------
> +
> +In linux/i2c/ads1015.h platform data is defined as:
> +
> +struct ads1015_platform_data {
> +	unsigned int exported_channels;
> +};
> +
> +exported_channels is a bitmask that specifies which inputs should be exported.
> +
> +Example:
> +struct ads1015_platform_data data = {
> +	.exported_channels = (1 << 2) | (1 << 4)
> +};
> +
> +In this case only in2_input and in4_input would be created.
> +
> +Devicetree
> +----------
> +
> +The ads1015 node may have an "exported-channels" property.
> +exported_channels is a bitmask that specifies which inputs should be exported.
> +
> +Example:
> +ads1015 at 49 {
> +	compatible = "ti,ads1015";
> +	reg = <0x49>;
> +	exported-channels = < 0x14 >;
> +};
> +
> +In this case only in2_input and in4_input would be created.

The control file layout in sysfs *must* be documented.  And once it is
merged any changes must be backwards compatible since it is a
userspace interface.  Are you happy with the sysfs interface as it
stands?  From looking at the chip datasheet, there seem to be a lot of
possible configurations that aren't reflected by the sysfs interface.
Nor do I see any way for userspace to discover what the measurements
actually represent (but I'm not even remotely familiar with the
hwmon/sensors architecture, so I'm not an expert on how things should be
done here).

> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 773e484..7e247f7 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -871,6 +871,16 @@ config SENSORS_SMSC47B397
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called smsc47b397.
>  
> +config SENSORS_ADS1015
> +	tristate "Texas Instruments ADS1015"
> +	depends on I2C
> +	help
> +	  If you say yes here you get support for Texas Instruments ADS1015
> +	  12-bit 4-input ADC device.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called ads1015.
> +
>  config SENSORS_ADS7828
>  	tristate "Texas Instruments ADS7828"
>  	depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index dde02d9..aae4036 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -29,6 +29,7 @@ obj-$(CONFIG_SENSORS_ADM1026)	+= adm1026.o
>  obj-$(CONFIG_SENSORS_ADM1029)	+= adm1029.o
>  obj-$(CONFIG_SENSORS_ADM1031)	+= adm1031.o
>  obj-$(CONFIG_SENSORS_ADM9240)	+= adm9240.o
> +obj-$(CONFIG_SENSORS_ADS1015)	+= ads1015.o
>  obj-$(CONFIG_SENSORS_ADS7828)	+= ads7828.o
>  obj-$(CONFIG_SENSORS_ADS7871)	+= ads7871.o
>  obj-$(CONFIG_SENSORS_ADT7411)	+= adt7411.o
> diff --git a/drivers/hwmon/ads1015.c b/drivers/hwmon/ads1015.c
> new file mode 100644
> index 0000000..7d593bb
> --- /dev/null
> +++ b/drivers/hwmon/ads1015.c
> @@ -0,0 +1,283 @@
> +/*
> + * ads1015.c - lm_sensors driver for ads1015 12-bit 4-input ADC
> + * (C) Copyright 2010
> + * Dirk Eibach, Guntermann & Drunck GmbH <eibach at gdsys.de>
> + *
> + * Based on the ads7828 driver by Steve Hardy.
> + *
> + * Datasheet available at: http://focus.ti.com/lit/ds/symlink/ads1015.pdf
> + *
> + * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/jiffies.h>
> +#include <linux/i2c.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/err.h>
> +#include <linux/mutex.h>
> +#include <linux/of.h>
> +
> +#include <linux/i2c/ads1015.h>
> +
> +/* ADS1015 registers */
> +enum {
> +	ADS1015_CONVERSION = 0,
> +	ADS1015_CONFIG = 1,
> +};
> +
> +/* PGA fullscale voltages in mV */
> +static const unsigned int fullscale_table[8] = {
> +	6144, 4096, 2048, 1024, 512, 256, 256, 256 };
> +
> +#define ADS1015_CONFIG_CHANNELS 8
> +#define ADS1015_DEFAULT_CHANNELS 0xff
> +
> +struct ads1015_data {
> +	struct device *hwmon_dev;
> +	struct mutex update_lock; /* mutex protect updates */
> +	struct attribute *attr_table[ADS1015_CONFIG_CHANNELS + 1];
> +	struct attribute_group attr_group;
> +};
> +
> +static s32 ads1015_read_reg(struct i2c_client *client, unsigned int reg)
> +{
> +	s32 data = i2c_smbus_read_word_data(client, reg);
> +
> +	return (data < 0) ? data : swab16(data);
> +}
> +
> +static s32 ads1015_write_reg(struct i2c_client *client, unsigned int reg,
> +			     u16 val)
> +{
> +	return i2c_smbus_write_word_data(client, reg, swab16(val));
> +}
> +
> +static int ads1015_read_value(struct i2c_client *client, unsigned int channel,
> +			      int *value)
> +{
> +	u16 config;
> +	s16 conversion;
> +	unsigned int pga;
> +	int fullscale;
> +	unsigned int k;
> +	struct ads1015_data *data = i2c_get_clientdata(client);
> +	int res;
> +
> +	mutex_lock(&data->update_lock);
> +
> +	/* get fullscale voltage */
> +	res = ads1015_read_reg(client, ADS1015_CONFIG);
> +	if (res < 0)
> +		goto err_unlock;
> +	config = res;
> +	pga = (config >> 9) & 0x0007;
> +	fullscale = fullscale_table[pga];
> +
> +	/* set channel and start single conversion */
> +	config &= ~(0x0007 << 12);
> +	config |= (1 << 15) | (1 << 8) | (channel & 0x0007) << 12;
> +
> +	/* wait until conversion finished */
> +	res = ads1015_write_reg(client, ADS1015_CONFIG, config);
> +	if (res < 0)
> +		goto err_unlock;
> +	for (k = 0; k < 5; ++k) {
> +		schedule_timeout(msecs_to_jiffies(1));
> +		res = ads1015_read_reg(client, ADS1015_CONFIG);
> +		if (res < 0)
> +			goto err_unlock;
> +		config = res;
> +		if (config & (1 << 15))
> +			break;
> +	}
> +	if (k == 5) {
> +		res = -EIO;
> +		goto err_unlock;
> +	}
> +
> +	res = ads1015_read_reg(client, ADS1015_CONVERSION);
> +	if (res < 0)
> +		goto err_unlock;
> +	conversion = res;
> +
> +	mutex_unlock(&data->update_lock);
> +
> +	*value = DIV_ROUND_CLOSEST(conversion * fullscale, 0x7ff0);
> +
> +	return 0;
> +
> +err_unlock:
> +	mutex_unlock(&data->update_lock);
> +	return res;
> +}
> +
> +/* sysfs callback function */
> +static ssize_t show_in(struct device *dev, struct device_attribute *da,
> +	char *buf)
> +{
> +	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
> +	struct i2c_client *client = to_i2c_client(dev);
> +	int in;
> +	int res;
> +
> +	res = ads1015_read_value(client, attr->index, &in);
> +
> +	return (res < 0) ? res : sprintf(buf, "%d\n", in);
> +}
> +
> +#define in_reg(offset)\

in_reg() is pretty generic.  Rename to something like
ads1015_input_attribute(offset)

> +static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
> +	NULL, offset)

Indent 'static SENSOR_DEVICE_ATTR(...'

> +
> +in_reg(0);
> +in_reg(1);
> +in_reg(2);
> +in_reg(3);
> +in_reg(4);
> +in_reg(5);
> +in_reg(6);
> +in_reg(7);
> +
> +static struct attribute *all_attributes[] = {
> +	&sensor_dev_attr_in0_input.dev_attr.attr,
> +	&sensor_dev_attr_in1_input.dev_attr.attr,
> +	&sensor_dev_attr_in2_input.dev_attr.attr,
> +	&sensor_dev_attr_in3_input.dev_attr.attr,
> +	&sensor_dev_attr_in4_input.dev_attr.attr,
> +	&sensor_dev_attr_in5_input.dev_attr.attr,
> +	&sensor_dev_attr_in6_input.dev_attr.attr,
> +	&sensor_dev_attr_in7_input.dev_attr.attr,
> +};
> +
> +/*
> + * Driver interface
> + */
> +
> +static int ads1015_remove(struct i2c_client *client)

static int __devexit ads1015_remove(struct i2c_client *client)

> +{
> +	struct ads1015_data *data = i2c_get_clientdata(client);
> +	hwmon_device_unregister(data->hwmon_dev);
> +	sysfs_remove_group(&client->dev.kobj, &data->attr_group);
> +	kfree(data);
> +	return 0;
> +}
> +
> +static unsigned int ads1015_get_exported_channels(struct i2c_client *client)
> +{
> +	struct ads1015_platform_data *pdata = dev_get_platdata(&client->dev);
> +#ifdef CONFIG_OF
> +	struct device_node *np = client->dev.of_node;
> +	const __be32 *of_channels;
> +	int of_channels_size;
> +#endif
> +
> +	/* prefer platform data */
> +	if (pdata)
> +		return pdata->exported_channels;
> +
> +#ifdef CONFIG_OF
> +	/* fallback on OF */
> +	of_channels = of_get_property(np, "exported-channels",
> +				      &of_channels_size);
> +	if (of_channels && (of_channels_size == sizeof(*of_channels)))
> +		return be32_to_cpup(of_channels);
> +#endif
> +
> +	/* fallback on default configuration */
> +	return ADS1015_DEFAULT_CHANNELS;
> +}
> +
> +static int ads1015_probe(struct i2c_client *client,

static int __devinit ads1015_probe(struct i2c_client *client,

> +			 const struct i2c_device_id *id)
> +{
> +	struct ads1015_data *data;
> +	int err;
> +	unsigned int exported_channels;
> +	unsigned int k;
> +	unsigned int n = 0;
> +
> +	data = kzalloc(sizeof(struct ads1015_data), GFP_KERNEL);
> +	if (!data) {
> +		err = -ENOMEM;
> +		goto exit;
> +	}
> +
> +	i2c_set_clientdata(client, data);
> +	mutex_init(&data->update_lock);
> +
> +	/* build sysfs attribute group */
> +	data->attr_group.attrs = data->attr_table;
> +	exported_channels = ads1015_get_exported_channels(client);
> +	for (k = 0; k < ADS1015_CONFIG_CHANNELS; ++k) {
> +		if (!(exported_channels & (1<<k)))
> +			continue;
> +		data->attr_table[n++] =
> +			all_attributes[k];
> +	}
> +	err = sysfs_create_group(&client->dev.kobj, &data->attr_group);
> +	if (err)
> +		goto exit_free;

I suspect there are lifecycle issues here.  Attributes should not be
added to a device after the device is registered.  If adding
attributes, then a new struct device should be allocated, added to the
attribute group, and then registered as a child of the i2c_device.
Otherwise the attributes are not available at uevent time, which means
userspace (udev) may not be able to do the right things with the
device when the device appears.

Kay/GregKH, do I have this right?

> +
> +	data->hwmon_dev = hwmon_device_register(&client->dev);
> +	if (IS_ERR(data->hwmon_dev)) {
> +		err = PTR_ERR(data->hwmon_dev);
> +		goto exit_remove;
> +	}
> +
> +	return 0;
> +
> +exit_remove:
> +	sysfs_remove_group(&client->dev.kobj, &data->attr_group);
> +exit_free:
> +	kfree(data);
> +exit:
> +	return err;
> +}
> +
> +static const struct i2c_device_id ads1015_id[] = {
> +	{ "ads1015", 0 },
> +	{ }

Should use initializers here:

	{ .name = "ads1015, },
	{}

The '0' can be omitted because by default it is initialized to zero.

> +};
> +MODULE_DEVICE_TABLE(i2c, ads1015_id);
> +
> +static struct i2c_driver ads1015_driver = {
> +	.driver = {
> +		.name = "ads1015",

		.owner = THIS_MODULE,
> +	},
> +	.probe = ads1015_probe,
> +	.remove = ads1015_remove,

.remove = __devexit_p(ads1015_remove),

> +	.id_table = ads1015_id,
> +};
> +
> +static int __init sensors_ads1015_init(void)
> +{
> +	return i2c_add_driver(&ads1015_driver);
> +}
> +
> +static void __exit sensors_ads1015_exit(void)
> +{
> +	i2c_del_driver(&ads1015_driver);
> +}
> +
> +MODULE_AUTHOR("Dirk Eibach <eibach at gdsys.de>");
> +MODULE_DESCRIPTION("ADS1015 driver");
> +MODULE_LICENSE("GPL");
> +
> +module_init(sensors_ads1015_init);
> +module_exit(sensors_ads1015_exit);

Move module_init and module_exit to directly below each functions they
are registering.


> diff --git a/include/linux/i2c/ads1015.h b/include/linux/i2c/ads1015.h
> new file mode 100644
> index 0000000..8541c6a
> --- /dev/null
> +++ b/include/linux/i2c/ads1015.h
> @@ -0,0 +1,28 @@
> +/*
> + * Platform Data for ADS1015 12-bit 4-input ADC
> + * (C) Copyright 2010
> + * Dirk Eibach, Guntermann & Drunck GmbH <eibach at gdsys.de>
> + *
> + * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
> + */
> +
> +#ifndef LINUX_ADS1015_H
> +#define LINUX_ADS1015_H
> +
> +struct ads1015_platform_data {
> +	unsigned int exported_channels;
> +};
> +
> +#endif /* LINUX_ADS1015_H */
> -- 
> 1.5.6.5
> 
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