[PATCH 2/3] iio: chemical: vz89x: add support for VZ89TE part

[Matt Ranostay <mranostay@gmail.com>]

Add support the VZ89TE variant which removes the voc_short channel,
and has CRC check for data transactions.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
---
 drivers/iio/chemical/vz89x.c | 149 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 123 insertions(+), 26 deletions(-)

diff --git a/drivers/iio/chemical/vz89x.c b/drivers/iio/chemical/vz89x.c
index f498228e044d..0347761ebdba 100644
--- a/drivers/iio/chemical/vz89x.c
+++ b/drivers/iio/chemical/vz89x.c
@@ -19,20 +19,33 @@
 #include <linux/mutex.h>
 #include <linux/init.h>
 #include <linux/i2c.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 
 #define VZ89X_REG_MEASUREMENT		0x09
+#define VZ89TE_REG_MEASUREMENT		0x0c
+
+#define VZ89X_REG_WRITE_SIZE		3
+#define VZ89TE_REG_WRITE_SIZE		6
+
 #define VZ89X_REG_MEASUREMENT_SIZE	6
+#define VZ89TE_REG_MEASUREMENT_SIZE	7
 
 #define VZ89X_VOC_CO2_IDX		0
 #define VZ89X_VOC_SHORT_IDX		1
 #define VZ89X_VOC_TVOC_IDX		2
 #define VZ89X_VOC_RESISTANCE_IDX	3
 
+#define VZ89TE_VOC_TVOC_IDX		0
+#define VZ89TE_VOC_CO2_IDX		1
+#define VZ89TE_VOC_RESISTANCE_IDX	2
+
 enum {
 	VZ89X,
+	VZ89TE,
 };
 
 struct vz89x_data {
@@ -79,6 +92,40 @@ static const struct iio_chan_spec vz89x_channels[] = {
 		.info_mask_separate =
 			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
 		.address = VZ89X_VOC_RESISTANCE_IDX,
+		.scan_index = -1,
+		.scan_type = {
+			.endianness = IIO_LE,
+		},
+	},
+};
+
+static const struct iio_chan_spec vz89te_channels[] = {
+	{
+		.type = IIO_CONCENTRATION,
+		.channel2 = IIO_MOD_VOC,
+		.modified = 1,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
+		.address = VZ89TE_VOC_TVOC_IDX,
+	},
+
+	{
+		.type = IIO_CONCENTRATION,
+		.channel2 = IIO_MOD_CO2,
+		.modified = 1,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
+		.address = VZ89TE_VOC_CO2_IDX,
+	},
+	{
+		.type = IIO_RESISTANCE,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.address = VZ89TE_VOC_RESISTANCE_IDX,
+		.scan_index = -1,
+		.scan_type = {
+			.endianness = IIO_BE,
+		},
 	},
 };
 
@@ -110,12 +157,27 @@ static int vz89x_measurement_is_valid(struct vz89x_data *data)
 	return !!(data->buffer[data->read_size - 1] > 0);
 }
 
+/* VZ89TE device has a modified CRC-8 two complement check */
+static int vz89te_measurement_is_valid(struct vz89x_data *data)
+{
+	u8 crc = 0;
+	int i, sum = 0;
+
+	for (i = 0; i < (data->read_size - 1); i++) {
+		sum = crc + data->buffer[i];
+		crc = sum;
+		crc += sum / 256;
+	}
+
+	return !((0xff - crc) == data->buffer[data->read_size - 1]);
+}
+
 static int vz89x_i2c_xfer(struct vz89x_data *data, u8 cmd)
 {
 	struct i2c_client *client = data->client;
 	struct i2c_msg msg[2];
 	int ret;
-	u8 buf[3] = { cmd, 0, 0};
+	u8 buf[6] = { cmd, 0, 0, 0, 0, 0xf3};
 
 	msg[0].addr = client->addr;
 	msg[0].flags = client->flags;
@@ -173,11 +235,24 @@ static int vz89x_get_measurement(struct vz89x_data *data)
 	return 0;
 }
 
-static int vz89x_get_resistance_reading(struct vz89x_data *data)
+static int vz89x_get_resistance_reading(struct vz89x_data *data,
+					struct iio_chan_spec const *chan,
+					int *val)
 {
-	u8 *buf = &data->buffer[VZ89X_VOC_RESISTANCE_IDX];
+	u32 tmp = *((u32 *) ((u8 *) &data->buffer[chan->address]));
+
+	switch (chan->scan_type.endianness) {
+	case IIO_LE:
+		*val = le32_to_cpu(tmp) & GENMASK(23, 0);
+		break;
+	case IIO_BE:
+		*val = be32_to_cpu(tmp) >> 8;
+		break;
+	default:
+		return -EINVAL;
+	}
 
-	return buf[0] | (buf[1] << 8);
+	return 0;
 }
 
 static int vz89x_read_raw(struct iio_dev *indio_dev,
@@ -196,15 +271,15 @@ static int vz89x_read_raw(struct iio_dev *indio_dev,
 		if (ret)
 			return ret;
 
-		switch (chan->address) {
-		case VZ89X_VOC_CO2_IDX:
-		case VZ89X_VOC_SHORT_IDX:
-		case VZ89X_VOC_TVOC_IDX:
+		switch (chan->type) {
+		case IIO_CONCENTRATION:
 			*val = data->buffer[chan->address];
 			return IIO_VAL_INT;
-		case VZ89X_VOC_RESISTANCE_IDX:
-			*val = vz89x_get_resistance_reading(data);
-			return IIO_VAL_INT;
+		case IIO_RESISTANCE:
+			ret = vz89x_get_resistance_reading(data, chan, val);
+			if (!ret)
+				return IIO_VAL_INT;
+			break;
 		default:
 			return -EINVAL;
 		}
@@ -219,12 +294,12 @@ static int vz89x_read_raw(struct iio_dev *indio_dev,
 		}
 		break;
 	case IIO_CHAN_INFO_OFFSET:
-		switch (chan->address) {
-		case VZ89X_VOC_CO2_IDX:
+		switch (chan->channel2) {
+		case IIO_MOD_CO2:
 			*val = 44;
 			*val2 = 250000;
 			return IIO_VAL_INT_PLUS_MICRO;
-		case VZ89X_VOC_TVOC_IDX:
+		case IIO_MOD_VOC:
 			*val = -13;
 			return IIO_VAL_INT;
 		default:
@@ -241,11 +316,20 @@ static const struct iio_info vz89x_info = {
 	.driver_module	= THIS_MODULE,
 };
 
+static const struct of_device_id vz89x_dt_ids[] = {
+	{ .compatible = "sgx,vz89x", .data = (void *) VZ89X },
+	{ .compatible = "sgx,vz89te", .data = (void *) VZ89TE },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, vz89x_dt_ids);
+
 static int vz89x_probe(struct i2c_client *client,
 		       const struct i2c_device_id *id)
 {
 	struct iio_dev *indio_dev;
 	struct vz89x_data *data;
+	const struct of_device_id *of_id;
+	int chip_id;
 
 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 	if (!indio_dev)
@@ -260,13 +344,15 @@ static int vz89x_probe(struct i2c_client *client,
 	else
 		return -EOPNOTSUPP;
 
+	of_id = of_match_device(vz89x_dt_ids, &client->dev);
+	if (!of_id)
+		chip_id = id->driver_data;
+	else
+		chip_id = (unsigned long)of_id->data;
+
 	i2c_set_clientdata(client, indio_dev);
 	data->client = client;
 	data->last_update = jiffies - HZ;
-	data->cmd = VZ89X_REG_MEASUREMENT;
-	data->write_size = 3;
-	data->read_size = VZ89X_REG_MEASUREMENT_SIZE;
-	data->valid = &vz89x_measurement_is_valid;
 	mutex_init(&data->lock);
 
 	indio_dev->dev.parent = &client->dev;
@@ -274,24 +360,35 @@ static int vz89x_probe(struct i2c_client *client,
 	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);
+	switch (chip_id) {
+	case VZ89X:
+		indio_dev->channels = vz89x_channels;
+		indio_dev->num_channels = ARRAY_SIZE(vz89x_channels);
+		data->cmd = VZ89X_REG_MEASUREMENT;
+		data->write_size = VZ89X_REG_WRITE_SIZE;
+		data->read_size = VZ89X_REG_MEASUREMENT_SIZE;
+		data->valid = &vz89x_measurement_is_valid;
+		break;
+	case VZ89TE:
+		indio_dev->channels = vz89te_channels;
+		indio_dev->num_channels = ARRAY_SIZE(vz89te_channels);
+		data->cmd = VZ89TE_REG_MEASUREMENT;
+		data->write_size = VZ89TE_REG_WRITE_SIZE;
+		data->read_size = VZ89TE_REG_MEASUREMENT_SIZE;
+		data->valid = &vz89te_measurement_is_valid;
+		break;
+	}
 
 	return devm_iio_device_register(&client->dev, indio_dev);
 }
 
 static const struct i2c_device_id vz89x_id[] = {
 	{ "vz89x", VZ89X },
+	{ "vz89te", VZ89TE },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, vz89x_id);
 
-static const struct of_device_id vz89x_dt_ids[] = {
-	{ .compatible = "sgx,vz89x", .data = (void *) VZ89X },
-	{ }
-};
-MODULE_DEVICE_TABLE(of, vz89x_dt_ids);
-
 static struct i2c_driver vz89x_driver = {
 	.driver = {
 		.name	= "vz89x",
-- 
2.7.4