[PATCH 4/6] iio: adc: ltc2497: add 2x speed mode support for the LTC2493

[Andrei Stancovici via B4 Relay]

From: Andrei Stancovici <andrei.stancovici@xxxxxxxxxx>

The LTC2493 supports the same SPD 2x conversion-speed mode as the
LTC2499, using the same config word and conversion times.  Expose it
through sampling_frequency and sampling_frequency_available on the
voltage channels.  The temperature channel ignores the mode and carries
no sampling_frequency.

Tested on live LTC2493 hardware connected through an IIO network
backend: 1x/2x switching works, voltage reads succeed at both rates, and
the temperature channel carries no sampling_frequency attribute.

Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/2493fe.pdf
Signed-off-by: Andrei Stancovici <andrei.stancovici@xxxxxxxxxx>
---
 drivers/iio/adc/ltc2497-core.c | 6 +++++-
 drivers/iio/adc/ltc2497.c      | 1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ltc2497-core.c b/drivers/iio/adc/ltc2497-core.c
index 87eade46beb5..816312bf0e90 100644
--- a/drivers/iio/adc/ltc2497-core.c
+++ b/drivers/iio/adc/ltc2497-core.c
@@ -362,6 +362,7 @@ static const struct iio_chan_spec _name[] = {                           \
 }
 
 LTC2493_DEFINE_CHANNELS(ltc2493_channel, 0);
+LTC2493_DEFINE_CHANNELS(ltc2493_channel_samp_freq, BIT(IIO_CHAN_INFO_SAMP_FREQ));
 
 static const struct iio_info ltc2497core_info = {
 	.read_raw = ltc2497core_read_raw,
@@ -387,7 +388,10 @@ int ltc2497core_probe(struct device *dev, struct iio_dev *indio_dev)
 	indio_dev->info = &ltc2497core_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	if (ddata->chip_info->four_channel) {
-		indio_dev->channels = ltc2493_channel;
+		if (ddata->chip_info->has_speed_mode)
+			indio_dev->channels = ltc2493_channel_samp_freq;
+		else
+			indio_dev->channels = ltc2493_channel;
 		indio_dev->num_channels = ARRAY_SIZE(ltc2493_channel);
 	} else {
 		if (ddata->chip_info->has_speed_mode)
diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c
index 12c8a2fecc07..a655b04e2454 100644
--- a/drivers/iio/adc/ltc2497.c
+++ b/drivers/iio/adc/ltc2497.c
@@ -175,6 +175,7 @@ static const struct ltc2497_chip_info ltc2497_info[] = {
 		.resolution = 24,
 		.name = "ltc2493",
 		.has_temp = true,
+		.has_speed_mode = true,
 		.four_channel = true,
 	},
 	[TYPE_LTC2497] = {

-- 
2.43.0