[PATCH v2] hwmon: Add support for Texas Instruments ADS1015

[Dirk Eibach]

Signed-off-by: Dirk Eibach <eibach@xxxxxxxx>
---
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()

 Documentation/hwmon/ads1015 |   33 ++++++
 drivers/hwmon/Kconfig       |   10 ++
 drivers/hwmon/Makefile      |    1 +
 drivers/hwmon/ads1015.c     |  246 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 290 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/hwmon/ads1015
 create mode 100644 drivers/hwmon/ads1015.c

diff --git a/Documentation/hwmon/ads1015 b/Documentation/hwmon/ads1015
new file mode 100644
index 0000000..e2dc689
--- /dev/null
+++ b/Documentation/hwmon/ads1015
@@ -0,0 +1,33 @@
+Kernel driver ads1015
+=====================
+
+Supported chips:
+  * Texas Instruments ADS1015
+    Prefix: 'ads1015'
+    Addresses scanned: I2C 0x48, 0x49, 0x4a, 0x4b
+    Datasheet: Publicly available at the Texas Instruments website :
+               http://focus.ti.com/lit/ds/symlink/ads1015.pdf
+
+Authors:
+        Dirk Eibach, Guntermann & Drunck GmbH <eibach@xxxxxxxx>
+
+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.
+
+On certain systems it makes sense to access absolute voltage values as well
+as voltage differences. So all available combinations are made available by
+8 "virtual" inputs:
+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.
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..7fb30ae
--- /dev/null
+++ b/drivers/hwmon/ads1015.c
@@ -0,0 +1,246 @@
+/*
+ * ads1015.c - lm_sensors driver for ads1015 12-bit 4-input ADC
+ * (C) Copyright 2010
+ * Dirk Eibach, Guntermann & Drunck GmbH <eibach@xxxxxxxx>
+ *
+ * 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>
+
+/* 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 };
+
+/* Addresses to scan */
+static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
+	I2C_CLIENT_END };
+
+/* Each client has this additional data */
+struct ads1015_data {
+	struct device *hwmon_dev;
+	struct mutex update_lock; /* mutex protect updates */
+};
+
+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)
+		return -EIO;
+
+	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)\
+static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
+	NULL, offset)
+
+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 *ads1015_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,
+	NULL
+};
+
+static const struct attribute_group ads1015_group = {
+	.attrs = ads1015_attributes,
+};
+
+static int 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, &ads1015_group);
+	kfree(data);
+	return 0;
+}
+
+static int ads1015_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct ads1015_data *data;
+	int err;
+
+	data = kzalloc(sizeof(struct ads1015_data), GFP_KERNEL);
+	if (!data) {
+		err = -ENOMEM;
+		goto exit;
+	}
+
+	i2c_set_clientdata(client, data);
+	mutex_init(&data->update_lock);
+
+	/* Register sysfs hooks */
+	err = sysfs_create_group(&client->dev.kobj, &ads1015_group);
+	if (err)
+		goto exit_free;
+
+	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, &ads1015_group);
+exit_free:
+	kfree(data);
+exit:
+	return err;
+}
+
+static const struct i2c_device_id ads1015_id[] = {
+	{ "ads1015", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ads1015_id);
+
+/* This is the driver that will be inserted */
+static struct i2c_driver ads1015_driver = {
+	.class = I2C_CLASS_HWMON,
+	.driver = {
+		.name = "ads1015",
+	},
+	.probe = ads1015_probe,
+	.remove = ads1015_remove,
+	.id_table = ads1015_id,
+	.address_list = normal_i2c,
+};
+
+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@xxxxxxxx>");
+MODULE_DESCRIPTION("ADS1015 driver");
+MODULE_LICENSE("GPL");
+
+module_init(sensors_ads1015_init);
+module_exit(sensors_ads1015_exit);
-- 
1.5.6.5

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