iio: adc: ad7476: Add LTC2314-14 support

The LTC2314-14 is a 14-bit, 4.5Msps, serial sampling A/D converter that draws only
6.2mA from a wide range analog supply adjustable from 2.7V to 5.25V.
Signed-off-by: Dragos Bogdan <dragos.bogdan@analog.com>
Signed-off-by: Mircea Caprioru <mircea.caprioru@analog.com>
Link: https://lore.kernel.org/r/20201216083639.89425-1-mircea.caprioru@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad7476.c

@@ -67,6 +67,7 @@ enum ad7476_supported_device_ids {
 	ID_ADS7866,
 	ID_ADS7867,
 	ID_ADS7868,
+	ID_LTC2314_14,
 };
 
 static void ad7091_convst(struct ad7476_state *st)
@@ -250,6 +251,10 @@ static const struct ad7476_chip_info ad7476_chip_info_tbl[] = {
 		.channel[0] = ADS786X_CHAN(8),
 		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
 	},
+	[ID_LTC2314_14] = {
+		.channel[0] = AD7940_CHAN(14),
+		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	},
 };
 
 static const struct iio_info ad7476_info = {
@@ -365,6 +370,7 @@ static const struct spi_device_id ad7476_id[] = {
 	{"ads7866", ID_ADS7866},
 	{"ads7867", ID_ADS7867},
 	{"ads7868", ID_ADS7868},
+	{"ltc2314-14", ID_LTC2314_14},
 	{}
 };
 MODULE_DEVICE_TABLE(spi, ad7476_id);