[RFC v2 4/4] iio: chemical: add SGX VZ89x VOC sensor support

[Matt Ranostay <mranostay@gmail.com>]

Add support for VZ89X sensors VOC and CO2 reporting channels in
percentage which can be converted to part per million.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
---
 .../ABI/testing/sysfs-bus-iio-chemical-vz89x       |  30 +++
 .../devicetree/bindings/i2c/trivial-devices.txt    |   1 +
 drivers/iio/Kconfig                                |   1 +
 drivers/iio/Makefile                               |   1 +
 drivers/iio/chemical/Makefile                      |   6 +
 drivers/iio/chemical/vz89x.c                       | 236 +++++++++++++++++++++
 6 files changed, 275 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
 create mode 100644 drivers/iio/chemical/Makefile
 create mode 100644 drivers/iio/chemical/vz89x.c

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x b/Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
new file mode 100644
index 0000000..74f2a35
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
@@ -0,0 +1,30 @@
+What:		/sys/bus/iio/devices/iio:deviceX/in_concentration_CO2_raw
+Date:		September 2015
+KernelVersion:	4.3
+Contact:	Matt Ranostay <mranostay@gmail.com>
+Description:
+		Get the unscaled, and no offset applied CO2 gas percentage
+		value.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_concentration_VOC_short_raw
+Date:		September 2015
+KernelVersion:	4.3
+Contact:	Matt Ranostay <mranostay@gmail.com>
+Description:
+		Get the raw calibration VOC value from the sensor.
+		This value has little application outside of calibration.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_concentration_tVOC_raw
+Date:		September 2015
+KernelVersion:	4.3
+Contact:	Matt Ranostay <mranostay@gmail.com>
+Description:
+		Get the unscaled, and no offset applied total VOC gas
+		percentage value.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_resistance_raw
+Date:		September 2015
+KernelVersion:	4.3
+Contact:	Matt Ranostay <mranostay@gmail.com>
+Description:
+		Get the unscaled sensor resistance value.
diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
index d77d412..a550216 100644
--- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
+++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
@@ -88,6 +88,7 @@ ricoh,rs5c372b		I2C bus SERIAL INTERFACE REAL-TIME CLOCK IC
 ricoh,rv5c386		I2C bus SERIAL INTERFACE REAL-TIME CLOCK IC
 ricoh,rv5c387a		I2C bus SERIAL INTERFACE REAL-TIME CLOCK IC
 samsung,24ad0xd1	S524AD0XF1 (128K/256K-bit Serial EEPROM for Low Power)
+sgx,vz89x		SGX Sensortech VZ89X Sensors
 sii,s35390a		2-wire CMOS real-time clock
 skyworks,sky81452	Skyworks SKY81452: Six-Channel White LED Driver with Touch Panel Bias Supply
 st-micro,24c256		i2c serial eeprom  (24cxx)
diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index 4011eff..9664e9c 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -61,6 +61,7 @@ config IIO_CONSUMERS_PER_TRIGGER
 source "drivers/iio/accel/Kconfig"
 source "drivers/iio/adc/Kconfig"
 source "drivers/iio/amplifiers/Kconfig"
+source "drivers/iio/chemical/Kconfig"
 source "drivers/iio/common/Kconfig"
 source "drivers/iio/dac/Kconfig"
 source "drivers/iio/frequency/Kconfig"
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 698afc2..2288684 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_IIO_KFIFO_BUF) += kfifo_buf.o
 obj-y += accel/
 obj-y += adc/
 obj-y += amplifiers/
+obj-y += chemical/
 obj-y += common/
 obj-y += dac/
 obj-y += gyro/
diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
new file mode 100644
index 0000000..7292f2d
--- /dev/null
+++ b/drivers/iio/chemical/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for IIO chemical sensors
+#
+
+# When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_VZ89X)		+= vz89x.o
diff --git a/drivers/iio/chemical/vz89x.c b/drivers/iio/chemical/vz89x.c
new file mode 100644
index 0000000..ac381cc
--- /dev/null
+++ b/drivers/iio/chemical/vz89x.c
@@ -0,0 +1,236 @@
+/*
+ * vz89x.c - Support for SGX Sensortech MiCS VZ89X VOC sensors
+ *
+ * Copyright (C) 2015 Matt Ranostay <mranostay@gmail.com>
+ *
+ * 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.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define VZ89X_REG_MEASUREMENT		0x09
+#define VZ89X_REG_MEASUREMENT_SIZE	6
+
+#define VZ89X_VOC_CO2_IDX		0
+#define VZ89X_VOC_SHORT_IDX		1
+#define VZ89X_VOC_TVOC_IDX		2
+#define VZ89X_VOC_RESISTANCE_IDX	3
+
+struct vz89x_data {
+	struct i2c_client *client;
+	struct mutex lock;
+	unsigned long last_update;
+
+	u8 buffer[VZ89X_REG_MEASUREMENT_SIZE];
+};
+
+static const struct iio_chan_spec vz89x_channels[] = {
+	{
+		.type = IIO_CONCENTRATION,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_OFFSET) |
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.address = VZ89X_VOC_CO2_IDX,
+		.extend_name = "CO2",
+	},
+	{
+		.type = IIO_CONCENTRATION,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.address = VZ89X_VOC_SHORT_IDX,
+		.extend_name = "VOC_short",
+	},
+	{
+		.type = IIO_CONCENTRATION,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.address = VZ89X_VOC_TVOC_IDX,
+		.extend_name = "tVOC",
+	},
+	{
+		.type = IIO_RESISTANCE,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.address = VZ89X_VOC_RESISTANCE_IDX,
+	},
+};
+
+static int vz89x_get_measurement(struct vz89x_data *data)
+{
+	int ret;
+	int i;
+
+	/* sensor can only be polled once a second max per datasheet */
+	if (!time_after(jiffies, data->last_update + HZ))
+		return 0;
+
+	ret = i2c_smbus_write_word_data(data->client,
+					VZ89X_REG_MEASUREMENT, 0);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < VZ89X_REG_MEASUREMENT_SIZE; i++) {
+		ret = i2c_smbus_read_byte(data->client);
+		if (ret < 0)
+			return ret;
+		data->buffer[i] = ret;
+	}
+
+	data->last_update = jiffies;
+
+	return 0;
+}
+
+static int vz89x_get_resistance_reading(struct vz89x_data *data)
+{
+	u8 *buf = &data->buffer[VZ89X_VOC_TVOC_IDX];
+
+	return buf[0] | ((u16)buf[1] << 8) | ((u32)buf[2] << 16);
+}
+
+static int vz89x_get_channel_scale(struct iio_chan_spec const *chan,
+				   int *val, int *val2)
+{
+	switch (chan->address) {
+	case VZ89X_VOC_CO2_IDX:
+		*val = 1600;
+		*val2 = 229;
+		return IIO_VAL_FRACTIONAL;
+	case VZ89X_VOC_TVOC_IDX:
+		*val = 1000;
+		*val2 = 229;
+		return IIO_VAL_FRACTIONAL;
+	}
+
+	return -EINVAL;
+}
+
+static int vz89x_read_raw(struct iio_dev *indio_dev,
+			  struct iio_chan_spec const *chan, int *val,
+			  int *val2, long mask)
+{
+	struct vz89x_data *data = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&data->lock);
+		ret = vz89x_get_measurement(data);
+		mutex_unlock(&data->lock);
+
+		if (ret)
+			return ret;
+
+		switch (chan->address) {
+		case VZ89X_VOC_CO2_IDX:
+			*val = 0;
+			*val2 = data->buffer[chan->address] - 13;
+			return IIO_VAL_INT_PLUS_MICRO;
+		case VZ89X_VOC_SHORT_IDX:
+			*val = data->buffer[chan->address] - 13;
+			return IIO_VAL_INT;
+		case VZ89X_VOC_TVOC_IDX:
+			*val = 0;
+			*val2 = data->buffer[chan->address] - 13;
+			return IIO_VAL_INT_PLUS_NANO;
+		case VZ89X_VOC_RESISTANCE_IDX:
+			*val = vz89x_get_resistance_reading(data);
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_RESISTANCE:
+			*val = 10;
+			return IIO_VAL_INT;
+		case IIO_CONCENTRATION:
+			return vz89x_get_channel_scale(chan, val, val2);
+		default:
+			return -EINVAL;
+		}
+		break;
+	case IIO_CHAN_INFO_OFFSET:
+		*val = 0;
+		*val2 = 400;
+		return IIO_VAL_INT_PLUS_MICRO;
+	}
+
+	return ret;
+}
+
+static const struct iio_info vz89x_info = {
+	.driver_module	= THIS_MODULE,
+	.read_raw	= vz89x_read_raw,
+};
+
+static int vz89x_probe(struct i2c_client *client,
+		       const struct i2c_device_id *id)
+{
+	struct iio_dev *indio_dev;
+	struct vz89x_data *data;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA |
+				     I2C_FUNC_SMBUS_BYTE))
+		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;
+	data->last_update = jiffies - HZ;
+	mutex_init(&data->lock);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &vz89x_info,
+	indio_dev->name = dev_name(&client->dev);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	indio_dev->channels = vz89x_channels;
+	indio_dev->num_channels = ARRAY_SIZE(vz89x_channels);
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id vz89x_id[] = {
+	{ "vz89x", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, vz89x_id);
+
+static const struct of_device_id vz89x_dt_ids[] = {
+	{ .compatible = "sgx,vz89x" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, vz89x_dt_ids);
+
+static struct i2c_driver vz89x_driver = {
+	.driver = {
+		.name	= "vz89x",
+		.of_match_table = of_match_ptr(vz89x_dt_ids),
+	},
+	.probe = vz89x_probe,
+	.id_table = vz89x_id,
+};
+module_i2c_driver(vz89x_driver);
+
+MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
+MODULE_DESCRIPTION("SGX Sensortech MiCS VZ89X VOC sensors");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1