hwmon: AD7314 driver (ported from IIO)

Driver for AD7314, ADT7301, and ADT7302, ported from IIO.

Currently dropped power down mode support.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
[guenter.roeck@ericsson.com: Added MODULE_DEVICE_TABLE]
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>

Documentation/hwmon/ad7314

@@ -0,0 +1,25 @@
+Kernel driver ad7314
+====================
+
+Supported chips:
+   * Analog Devices AD7314
+     Prefix: 'ad7314'
+     Datasheet: Publicly available at Analog Devices website.
+   * Analog Devices ADT7301
+     Prefix: 'adt7301'
+     Datasheet: Publicly available at Analog Devices website.
+   * Analog Devices ADT7302
+     Prefix: 'adt7302'
+     Datasheet: Publicly available at Analog Devices website.
+
+Description
+-----------
+
+Driver supports the above parts.  The ad7314 has a 10 bit
+sensor with 1lsb = 0.25 degrees centigrade. The adt7301 and
+adt7302 have 14 bit sensors with 1lsb = 0.03125 degrees centigrade.
+
+Notes
+-----
+
+Currently power down mode is not supported.

drivers/hwmon/Kconfig

@@ -68,6 +68,16 @@ config SENSORS_ABITUGURU3
 	  This driver can also be built as a module.  If so, the module
 	  will be called abituguru3.
 
+config SENSORS_AD7314
+	tristate "Analog Devices AD7314 and compatibles"
+	depends on SPI && EXPERIMENTAL
+	help
+	  If you say yes here you get support for the Analog Devices
+	  AD7314, ADT7301 and ADT7302 temperature sensors.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called ad7314.
+
 config SENSORS_AD7414
 	tristate "Analog Devices AD7414"
 	depends on I2C && EXPERIMENTAL

drivers/hwmon/Makefile

@@ -21,6 +21,7 @@ obj-$(CONFIG_SENSORS_W83791D)	+= w83791d.o
 
 obj-$(CONFIG_SENSORS_ABITUGURU)	+= abituguru.o
 obj-$(CONFIG_SENSORS_ABITUGURU3)+= abituguru3.o
+obj-$(CONFIG_SENSORS_AD7314)	+= ad7314.o
 obj-$(CONFIG_SENSORS_AD7414)	+= ad7414.o
 obj-$(CONFIG_SENSORS_AD7418)	+= ad7418.o
 obj-$(CONFIG_SENSORS_ADCXX)	+= adcxx.o

drivers/hwmon/ad7314.c

@@ -0,0 +1,186 @@
+/*
+ * AD7314 digital temperature sensor driver for AD7314, ADT7301 and ADT7302
+ *
+ * Copyright 2010 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ *
+ * Conversion to hwmon from IIO done by Jonathan Cameron <jic23@cam.ac.uk>
+ */
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/spi/spi.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+
+/*
+ * AD7314 power mode
+ */
+#define AD7314_PD		0x2000
+
+/*
+ * AD7314 temperature masks
+ */
+#define AD7314_TEMP_SIGN		0x200
+#define AD7314_TEMP_MASK		0x7FE0
+#define AD7314_TEMP_OFFSET		5
+
+/*
+ * ADT7301 and ADT7302 temperature masks
+ */
+#define ADT7301_TEMP_SIGN		0x2000
+#define ADT7301_TEMP_MASK		0x3FFF
+
+enum ad7314_variant {
+	adt7301,
+	adt7302,
+	ad7314,
+};
+
+struct ad7314_data {
+	struct spi_device	*spi_dev;
+	struct device		*hwmon_dev;
+	u16 rx ____cacheline_aligned;
+};
+
+static int ad7314_spi_read(struct ad7314_data *chip, s16 *data)
+{
+	int ret;
+
+	ret = spi_read(chip->spi_dev, (u8 *)&chip->rx, sizeof(chip->rx));
+	if (ret < 0) {
+		dev_err(&chip->spi_dev->dev, "SPI read error\n");
+		return ret;
+	}
+
+	*data = be16_to_cpu(chip->rx);
+
+	return ret;
+}
+
+static ssize_t ad7314_show_temperature(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct ad7314_data *chip = dev_get_drvdata(dev);
+	s16 data;
+	int ret;
+
+	ret = ad7314_spi_read(chip, &data);
+	if (ret < 0)
+		return ret;
+	switch (spi_get_device_id(chip->spi_dev)->driver_data) {
+	case ad7314:
+		data = (data & AD7314_TEMP_MASK) >> AD7314_TEMP_OFFSET;
+		data = (data << 6) >> 6;
+
+		return sprintf(buf, "%d\n", 250 * data);
+	case adt7301:
+	case adt7302:
+		/*
+		 * Documented as a 13 bit twos complement register
+		 * with a sign bit - which is a 14 bit 2's complement
+		 * register.  1lsb - 31.25 milli degrees centigrade
+		 */
+		data &= ADT7301_TEMP_MASK;
+		data = (data << 2) >> 2;
+
+		return sprintf(buf, "%d\n",
+			       DIV_ROUND_CLOSEST(data * 3125, 100));
+	default:
+		return -EINVAL;
+	}
+}
+
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
+			  ad7314_show_temperature, NULL, 0);
+
+static struct attribute *ad7314_attributes[] = {
+	&sensor_dev_attr_temp1_input.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group ad7314_group = {
+	.attrs = ad7314_attributes,
+};
+
+static int __devinit ad7314_probe(struct spi_device *spi_dev)
+{
+	int ret;
+	struct ad7314_data *chip;
+
+	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+	if (chip == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+	dev_set_drvdata(&spi_dev->dev, chip);
+
+	ret = sysfs_create_group(&spi_dev->dev.kobj, &ad7314_group);
+	if (ret < 0)
+		goto error_free_chip;
+	chip->hwmon_dev = hwmon_device_register(&spi_dev->dev);
+	if (IS_ERR(chip->hwmon_dev)) {
+		ret = PTR_ERR(chip->hwmon_dev);
+		goto error_remove_group;
+	}
+
+	return 0;
+error_remove_group:
+	sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);
+error_free_chip:
+	kfree(chip);
+error_ret:
+	return ret;
+}
+
+static int __devexit ad7314_remove(struct spi_device *spi_dev)
+{
+	struct ad7314_data *chip = dev_get_drvdata(&spi_dev->dev);
+
+	hwmon_device_unregister(chip->hwmon_dev);
+	sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);
+	kfree(chip);
+
+	return 0;
+}
+
+static const struct spi_device_id ad7314_id[] = {
+	{ "adt7301", adt7301 },
+	{ "adt7302", adt7302 },
+	{ "ad7314", ad7314 },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ad7314_id);
+
+static struct spi_driver ad7314_driver = {
+	.driver = {
+		.name = "ad7314",
+		.bus = &spi_bus_type,
+		.owner = THIS_MODULE,
+	},
+	.probe = ad7314_probe,
+	.remove = __devexit_p(ad7314_remove),
+	.id_table = ad7314_id,
+};
+
+static __init int ad7314_init(void)
+{
+	return spi_register_driver(&ad7314_driver);
+}
+module_init(ad7314_init);
+
+static __exit void ad7314_exit(void)
+{
+	spi_unregister_driver(&ad7314_driver);
+}
+module_exit(ad7314_exit);
+
+MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD7314, ADT7301 and ADT7302 digital"
+			" temperature sensor driver");
+MODULE_LICENSE("GPL v2");