[PATCH v2 2/5] iio: adc: mcp320x: remove device_index check for TX

[Vincent Whitchurch <vincent.whitchurch@axis.com>]

Replace the device_index switch with a TX value computation based on the
number of channels in the chip_info structure, so that the latter has
all the information needed to handle the variants.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
---
 drivers/iio/adc/mcp320x.c | 46 +++++++++++++++++++--------------------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/drivers/iio/adc/mcp320x.c b/drivers/iio/adc/mcp320x.c
index c71d90babb39..77fb4522a378 100644
--- a/drivers/iio/adc/mcp320x.c
+++ b/drivers/iio/adc/mcp320x.c
@@ -147,29 +147,34 @@ static int mcp3550_convert_rx(struct mcp320x *adc)
 	return (s32)raw;
 }
 
-static int mcp320x_channel_to_tx_data(int device_index,
-			const unsigned int channel, bool differential)
+static int mcp320x_channel_to_tx_data(const struct mcp320x_chip_info *info,
+				      const struct iio_chan_spec *channel)
 {
 	int start_bit = 1;
+	bool differential = channel->differential;
+	u8 address = channel->address;
+	/*
+	 * This happens to be the same as the last number of the model name for
+	 * multi-channel MCP300X and MCP320X.
+	 */
+	unsigned int num_nondiff_channels = info->num_channels / 2;
 
-	switch (device_index) {
-	case mcp3002:
-	case mcp3202:
+	switch (num_nondiff_channels) {
+	case 2:
 		return ((start_bit << 4) | (!differential << 3) |
-							(channel << 2));
-	case mcp3004:
-	case mcp3204:
-	case mcp3008:
-	case mcp3208:
+			(address << 2));
+	case 4:
+	case 8:
 		return ((start_bit << 6) | (!differential << 5) |
-							(channel << 2));
+			(address << 2));
 	default:
-		return -EINVAL;
+		return 0;
 	}
 }
 
-static int mcp320x_adc_conversion(struct mcp320x *adc, u8 channel,
-				  bool differential, int device_index, int *val)
+static int mcp320x_adc_conversion(struct mcp320x *adc,
+				  const struct iio_chan_spec *channel,
+				  int *val)
 {
 	const struct mcp320x_chip_info *info = adc->chip_info;
 	int ret;
@@ -185,8 +190,7 @@ static int mcp320x_adc_conversion(struct mcp320x *adc, u8 channel,
 
 	memset(&adc->rx_buf, 0, sizeof(adc->rx_buf));
 	if (adc->chip_info->num_channels > 1)
-		adc->tx_buf = mcp320x_channel_to_tx_data(device_index, channel,
-							 differential);
+		adc->tx_buf = mcp320x_channel_to_tx_data(info, channel);
 
 	ret = spi_sync(adc->spi, &adc->msg);
 	if (ret < 0)
@@ -203,16 +207,12 @@ static int mcp320x_read_raw(struct iio_dev *indio_dev,
 {
 	struct mcp320x *adc = iio_priv(indio_dev);
 	int ret = -EINVAL;
-	int device_index = 0;
 
 	mutex_lock(&adc->lock);
 
-	device_index = spi_get_device_id(adc->spi)->driver_data;
-
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
-		ret = mcp320x_adc_conversion(adc, channel->address,
-			channel->differential, device_index, val);
+		ret = mcp320x_adc_conversion(adc, channel, val);
 		if (ret < 0)
 			goto out;
 
@@ -452,8 +452,8 @@ static int mcp320x_probe(struct spi_device *spi)
 		 * conversions without delay between them resets the chip
 		 * and ensures all subsequent conversions succeed.
 		 */
-		mcp320x_adc_conversion(adc, 0, 1, device_index, &ret);
-		mcp320x_adc_conversion(adc, 0, 1, device_index, &ret);
+		mcp320x_adc_conversion(adc, &chip_info->channels[0], &ret);
+		mcp320x_adc_conversion(adc, &chip_info->channels[0], &ret);
 	}
 
 	adc->reg = devm_regulator_get(&spi->dev, "vref");
-- 
2.34.1