[PATCH] iio: temperature: mcp9808: add Microchip MCP9808 temperature sensor

[Alison Schofield]

IIO driver, perhaps a reference driver, since this sensor is already
supported in hwmon/jc42 driver.

Driver supports continuous conversion, resolution changes and
suspend/resume power ops.

Signed-off-by: Alison Schofield <amsfield22@xxxxxxxxx>
Cc: Daniel Baluta <daniel.baluta@xxxxxxxxx>
---
 drivers/iio/temperature/Kconfig   |  10 ++
 drivers/iio/temperature/Makefile  |   1 +
 drivers/iio/temperature/mcp9808.c | 269 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 280 insertions(+)
 create mode 100644 drivers/iio/temperature/mcp9808.c

diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig
index c4664e5..25915d2 100644
--- a/drivers/iio/temperature/Kconfig
+++ b/drivers/iio/temperature/Kconfig
@@ -3,6 +3,16 @@
 #
 menu "Temperature sensors"
 
+config MCP9808
+	tristate "MCP9808 temperature sensor"
+	depends on I2C
+	help
+	  If you say yes here you get support for the Microchip
+	  MCP9808 temperature sensor connected with I2C.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called mcp9808.
+
 config MLX90614
 	tristate "MLX90614 contact-less infrared sensor"
 	depends on I2C
diff --git a/drivers/iio/temperature/Makefile b/drivers/iio/temperature/Makefile
index 02bc79d..92cd1e6 100644
--- a/drivers/iio/temperature/Makefile
+++ b/drivers/iio/temperature/Makefile
@@ -2,6 +2,7 @@
 # Makefile for industrial I/O temperature drivers
 #
 
+obj-$(CONFIG_MCP9808) += mcp9808.o
 obj-$(CONFIG_MLX90614) += mlx90614.o
 obj-$(CONFIG_TMP006) += tmp006.o
 obj-$(CONFIG_TSYS01) += tsys01.o
diff --git a/drivers/iio/temperature/mcp9808.c b/drivers/iio/temperature/mcp9808.c
new file mode 100644
index 0000000..adab708
--- /dev/null
+++ b/drivers/iio/temperature/mcp9808.c
@@ -0,0 +1,269 @@
+/*
+ * mcp9808.c - Support for Microchip MCP9808 Digital Temperature Sensor
+ *
+ * Copyright (C) 2016 Alison Schofield <amsfield22@xxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/25095A.pdf
+ */
+
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define MCP9808_REG_CONFIG		0x01
+#define MCP9808_REG_TAMBIENT		0x05
+#define MCP9808_REG_MANUF_ID		0x06
+#define MCP9808_REG_DEVICE_ID		0x07
+#define MCP9808_REG_RESOLUTION		0x08
+
+#define MCP9808_CONFIG_DEFAULT		0x00
+#define MCP9808_CONFIG_SHUTDOWN		0x0100
+
+#define MCP9808_RES_DEFAULT		62500
+
+#define MCP9808_MANUF_ID		0x54
+#define MCP9808_DEVICE_ID		0x0400
+#define MCP9808_DEVICE_ID_MASK		0xff00
+
+struct mcp9808_data {
+	struct i2c_client *client;
+	struct mutex	   lock;	/* protect resolution changes  */
+	int		   res_index;	/* current resolution index    */
+};
+
+/* Resolution, MCP9808_REG_RESOLUTION bits, Conversion Time ms  */
+static const int mcp9808_res[][3] = {
+	{500000, 0,  30},
+	{250000, 1,  65},
+	{125000, 2, 130},
+	{ 62500, 3, 250},
+};
+
+static IIO_CONST_ATTR(temp_integration_time_available,
+	"0.5 0.25 0.125 0.0625");
+
+static struct attribute *mcp9808_attributes[] = {
+	&iio_const_attr_temp_integration_time_available.dev_attr.attr,
+	NULL
+};
+
+static struct attribute_group mcp9808_attribute_group = {
+	.attrs = mcp9808_attributes,
+};
+
+static int mcp9808_set_resolution(struct mcp9808_data *data, int val2)
+{
+	int i;
+	int ret = -EINVAL;
+	int conv_t = mcp9808_res[data->res_index][2];
+
+	for (i = 0; i < ARRAY_SIZE(mcp9808_res); i++) {
+		if (val2 == mcp9808_res[i][0]) {
+			mutex_lock(&data->lock);
+			ret = i2c_smbus_write_byte_data(data->client,
+							MCP9808_REG_RESOLUTION,
+							mcp9808_res[i][1]);
+			data->res_index = i;
+			mutex_unlock(&data->lock);
+
+			/* delay old + new conversion time */
+			msleep(conv_t + mcp9808_res[i][2]);
+			break;
+		}
+	}
+	return ret;
+}
+
+static int mcp9808_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *channel,
+			    int *val, int *val2, long mask)
+
+{
+	struct mcp9808_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = i2c_smbus_read_word_swapped(data->client,
+						  MCP9808_REG_TAMBIENT);
+		if (ret < 0)
+			return ret;
+		*val = sign_extend32(ret, 12);
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		*val2 = 62500;
+		return IIO_VAL_INT_PLUS_MICRO;
+
+	case IIO_CHAN_INFO_INT_TIME:
+		*val = 0;
+		*val2 = mcp9808_res[data->res_index][0];
+		return IIO_VAL_INT_PLUS_MICRO;
+
+	default:
+		break;
+	}
+
+	return -EINVAL;
+}
+
+static int mcp9808_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *channel,
+			     int val, int val2, long mask)
+{
+	struct mcp9808_data *data = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	if (mask == IIO_CHAN_INFO_INT_TIME) {
+		if (!val)
+			ret = mcp9808_set_resolution(data, val2);
+	}
+	return ret;
+}
+
+static const struct iio_chan_spec mcp9808_channels[] = {
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE) |
+			BIT(IIO_CHAN_INFO_INT_TIME)
+	}
+};
+
+static const struct iio_info mcp9808_info = {
+	.read_raw = mcp9808_read_raw,
+	.write_raw = mcp9808_write_raw,
+	.attrs = &mcp9808_attribute_group,
+	.driver_module = THIS_MODULE,
+};
+
+static bool mcp9808_check_id(struct i2c_client *client)
+{
+	int mid, did;
+
+	mid = i2c_smbus_read_word_swapped(client, MCP9808_REG_MANUF_ID);
+	if (mid < 0)
+		return false;
+
+	did = i2c_smbus_read_word_swapped(client, MCP9808_REG_DEVICE_ID);
+	if (did < 0)
+		return false;
+
+	return ((mid == MCP9808_MANUF_ID) &&
+		((did & MCP9808_DEVICE_ID_MASK) == MCP9808_DEVICE_ID));
+}
+
+static int mcp9808_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct iio_dev *indio_dev;
+	struct mcp9808_data *data;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA
+				     | I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
+		return -EOPNOTSUPP;
+
+	if (!mcp9808_check_id(client)) {
+		dev_err(&client->dev, "no MCP9808 sensor\n");
+		return -ENODEV;
+	}
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+	mutex_init(&data->lock);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->name = id->name;
+	indio_dev->info = &mcp9808_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = mcp9808_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mcp9808_channels);
+
+	/* set config register to power-on default */
+	ret = i2c_smbus_write_word_swapped(data->client, MCP9808_REG_CONFIG,
+					   MCP9808_CONFIG_DEFAULT);
+	if (ret < 0)
+		return ret;
+
+	/* set resolution register to power-on default */
+	ret = mcp9808_set_resolution(data, MCP9808_RES_DEFAULT);
+	if (ret < 0)
+		return ret;
+
+	return iio_device_register(indio_dev);
+}
+
+static int mcp9808_shutdown(struct mcp9808_data *data)
+{
+	return i2c_smbus_write_word_swapped(data->client, MCP9808_REG_CONFIG,
+					    MCP9808_CONFIG_SHUTDOWN);
+}
+
+static int mcp9808_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	iio_device_unregister(indio_dev);
+
+	return mcp9808_shutdown(iio_priv(indio_dev));
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int mcp9808_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+
+	return mcp9808_shutdown(iio_priv(indio_dev));
+}
+
+static int mcp9808_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct mcp9808_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = mcp9808_set_resolution(data, mcp9808_res[data->res_index][0]);
+	if (ret < 0)
+		return ret;
+
+	return i2c_smbus_write_word_swapped(data->client, MCP9808_REG_CONFIG,
+					    MCP9808_CONFIG_DEFAULT);
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(mcp9808_pm_ops, mcp9808_suspend, mcp9808_resume);
+
+static const struct i2c_device_id mcp9808_id[] = {
+	{ "mcp9808", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, mcp9808_id);
+
+static struct i2c_driver mcp9808_driver = {
+	.driver = {
+		.name	= "mcp9808",
+		.pm	= &mcp9808_pm_ops,
+	},
+	.probe = mcp9808_probe,
+	.remove = mcp9808_remove,
+	.id_table = mcp9808_id,
+};
+module_i2c_driver(mcp9808_driver);
+
+MODULE_AUTHOR("Alison Schofield <amsfield22@xxxxxxxxx>");
+MODULE_DESCRIPTION("MCP9808 Temperature Sensor Driver");
+MODULE_LICENSE("GPL v2");
-- 
2.1.4