iio: chemical: add SGX VZ89x VOC sensor support

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>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

7 files changed, 268 insertions, 0 deletions

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 000000000000..c0c1ea924535
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-chemical-vz89x
@@ -0,0 +1,7 @@
+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.
diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
index e1c07dd8792d..ed7ef4684aa3 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 6fe0d6524c9c..119c94df2b9e 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -47,6 +47,7 @@ config IIO_TRIGGERED_EVENT
 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 40995f366843..e2100554e3b4 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -13,6 +13,7 @@ obj-y += accel/
 obj-y += adc/
 obj-y += amplifiers/
 obj-y += buffer/
+obj-y += chemical/
 obj-y += common/
 obj-y += dac/
 obj-y += gyro/
diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
new file mode 100644
index 000000000000..3061b7299f0f
--- /dev/null
+++ b/drivers/iio/chemical/Kconfig
@@ -0,0 +1,15 @@
+#
+# Chemical sensors
+#
+
+menu "Chemical Sensors"
+
+config VZ89X
+        tristate "SGX Sensortech MiCS VZ89X VOC sensor"
+        depends on I2C
+        help
+          Say Y here to build I2C interface support for the SGX
+          Sensortech MiCS VZ89X VOC (Volatile Organic Compounds)
+          sensors
+
+endmenu
diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
new file mode 100644
index 000000000000..7292f2ded587
--- /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 000000000000..b45420039ca2
--- /dev/null
+++ b/drivers/iio/chemical/vz89x.c
@@ -0,0 +1,237 @@
+/*
+ * 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,
+                .channel2 = IIO_MOD_CO2,
+                .modified = 1,
+                .info_mask_separate =
+                        BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
+                .address = VZ89X_VOC_CO2_IDX,
+        },
+        {
+                .type = IIO_CONCENTRATION,
+                .channel2 = IIO_MOD_VOC,
+                .modified = 1,
+                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+                .address = VZ89X_VOC_SHORT_IDX,
+                .extend_name = "short",
+        },
+        {
+                .type = IIO_CONCENTRATION,
+                .channel2 = IIO_MOD_VOC,
+                .modified = 1,
+                .info_mask_separate =
+                        BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
+                .address = VZ89X_VOC_TVOC_IDX,
+        },
+        {
+                .type = IIO_RESISTANCE,
+                .info_mask_separate =
+                        BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+                .address = VZ89X_VOC_RESISTANCE_IDX,
+        },
+};
+
+static IIO_CONST_ATTR(in_concentration_co2_scale, "0.00000698689");
+static IIO_CONST_ATTR(in_concentration_voc_scale, "0.00000000436681223");
+
+static struct attribute *vz89x_attributes[] = {
+        &iio_const_attr_in_concentration_co2_scale.dev_attr.attr,
+        &iio_const_attr_in_concentration_voc_scale.dev_attr.attr,
+        NULL,
+};
+
+static const struct attribute_group vz89x_attrs_group = {
+        .attrs = vz89x_attributes,
+};
+
+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] | (buf[1] << 8) | (buf[2] << 16);
+}
+
+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:
+                case VZ89X_VOC_SHORT_IDX:
+                case VZ89X_VOC_TVOC_IDX:
+                        *val = data->buffer[chan->address];
+                        return IIO_VAL_INT;
+                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;
+                default:
+                        return -EINVAL;
+                }
+                break;
+        case IIO_CHAN_INFO_OFFSET:
+                switch (chan->address) {
+                case VZ89X_VOC_CO2_IDX:
+                        *val = 44;
+                        *val2 = 250000;
+                        return IIO_VAL_INT_PLUS_MICRO;
+                case VZ89X_VOC_TVOC_IDX:
+                        *val = -13;
+                        return IIO_VAL_INT;
+                default:
+                        return -EINVAL;
+                }
+        }
+
+        return ret;
+}
+
+static const struct iio_info vz89x_info = {
+        .attrs          = &vz89x_attrs_group,
+        .read_raw       = vz89x_read_raw,
+        .driver_module  = THIS_MODULE,
+};
+
+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");