* [PATCH v4 1/2] dt-bindings: adc: ltc2497: add support for ltc2305
2026-03-11 1:43 [PATCH v4 0/2] iio: adc: ltc2309: add support driver for ltc2305 Kyle Hsieh
@ 2026-03-11 1:43 ` Kyle Hsieh
2026-03-11 1:43 ` [PATCH v4 2/2] iio: adc: ltc2309: " Kyle Hsieh
1 sibling, 0 replies; 5+ messages in thread
From: Kyle Hsieh @ 2026-03-11 1:43 UTC (permalink / raw)
To: Lars-Peter Clausen, Michael Hennerich, Jonathan Cameron,
David Lechner, Nuno Sá, Andy Shevchenko, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Liam Beguin
Cc: Michael Hennerich, linux-iio, devicetree, linux-kernel,
Kyle Hsieh
Add documentation for the 2-channel LTC2305 ADC in the
existing ltc2497 binding.
This enables automatic device tree matching for LTC2305
while using the LTC2309 driver (drivers/iio/adc/ltc2309.c),
since both ADCs share the same I2C interface and 12-bit SAR architecture.
The main difference is the number of channels (LTC2305: 2, LTC2309: 8).
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Kyle Hsieh <kylehsieh1995@gmail.com>
---
Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml b/Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml
index 5cc6a9684077..c884b6e03767 100644
--- a/Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml
@@ -11,6 +11,12 @@ maintainers:
- Liam Beguin <liambeguin@gmail.com>
description: |
+ LTC2305:
+ low noise, low power, 2-channel, 12-bit successive approximation ADC with an
+ I2C compatible serial interface.
+
+ https://www.analog.com/media/en/technical-documentation/data-sheets/23015fb.pdf
+
LTC2309:
low noise, low power, 8-channel, 12-bit successive approximation ADC with an
I2C compatible serial interface.
@@ -28,6 +34,7 @@ description: |
properties:
compatible:
enum:
+ - lltc,ltc2305
- lltc,ltc2309
- lltc,ltc2497
- lltc,ltc2499
--
2.34.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v4 2/2] iio: adc: ltc2309: add support for ltc2305
2026-03-11 1:43 [PATCH v4 0/2] iio: adc: ltc2309: add support driver for ltc2305 Kyle Hsieh
2026-03-11 1:43 ` [PATCH v4 1/2] dt-bindings: adc: ltc2497: add support " Kyle Hsieh
@ 2026-03-11 1:43 ` Kyle Hsieh
2026-03-11 7:10 ` Andy Shevchenko
1 sibling, 1 reply; 5+ messages in thread
From: Kyle Hsieh @ 2026-03-11 1:43 UTC (permalink / raw)
To: Lars-Peter Clausen, Michael Hennerich, Jonathan Cameron,
David Lechner, Nuno Sá, Andy Shevchenko, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Liam Beguin
Cc: Michael Hennerich, linux-iio, devicetree, linux-kernel,
Kyle Hsieh
Add support for the 2-channel LTC2305 ADC in the existing LTC2309 driver.
The LTC2305 and LTC2309 share similar features: both are 12-bit,
low-noise, low-power SAR ADCs with an I2C interface.
The main difference is the number of channels: LTC2305 has 2 channels,
while LTC2309 has 8 channels.
Signed-off-by: Kyle Hsieh <kylehsieh1995@gmail.com>
---
drivers/iio/adc/ltc2309.c | 49 ++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 44 insertions(+), 5 deletions(-)
diff --git a/drivers/iio/adc/ltc2309.c b/drivers/iio/adc/ltc2309.c
index 5f0d947d0615..e6c15200a134 100644
--- a/drivers/iio/adc/ltc2309.c
+++ b/drivers/iio/adc/ltc2309.c
@@ -1,8 +1,10 @@
// SPDX-License-Identifier: GPL-2.0
/*
+ * The LTC2305 is a 2-Channel, 12-Bit SAR ADC with an I2C Interface.
* The LTC2309 is an 8-Channel, 12-Bit SAR ADC with an I2C Interface.
*
* Datasheet:
+ * https://www.analog.com/media/en/technical-documentation/data-sheets/23015fb.pdf
* https://www.analog.com/media/en/technical-documentation/data-sheets/2309fd.pdf
*
* Copyright (c) 2023, Liam Beguin <liambeguin@gmail.com>
@@ -41,6 +43,13 @@ struct ltc2309 {
};
/* Order matches expected channel address, See datasheet Table 1. */
+enum ltc2305_channels {
+ LTC2305_CH0_CH1 = 0x0,
+ LTC2305_CH1_CH0 = 0x4,
+ LTC2305_CH0 = 0x8,
+ LTC2305_CH1 = 0xc,
+};
+
enum ltc2309_channels {
LTC2309_CH0_CH1 = 0,
LTC2309_CH2_CH3,
@@ -80,6 +89,13 @@ enum ltc2309_channels {
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
}
+static const struct iio_chan_spec ltc2305_channels[] = {
+ LTC2309_CHAN(0, LTC2305_CH0),
+ LTC2309_CHAN(1, LTC2305_CH1),
+ LTC2309_DIFF_CHAN(0, 1, LTC2305_CH0_CH1),
+ LTC2309_DIFF_CHAN(1, 0, LTC2305_CH1_CH0),
+};
+
static const struct iio_chan_spec ltc2309_channels[] = {
LTC2309_CHAN(0, LTC2309_CH0),
LTC2309_CHAN(1, LTC2309_CH1),
@@ -99,6 +115,24 @@ static const struct iio_chan_spec ltc2309_channels[] = {
LTC2309_DIFF_CHAN(7, 6, LTC2309_CH7_CH6),
};
+struct ltc2309_chip_info {
+ const char *name;
+ const struct iio_chan_spec *channels;
+ int num_channels;
+};
+
+static const struct ltc2309_chip_info ltc2305_chip_info = {
+ .name = "ltc2305",
+ .channels = ltc2305_channels,
+ .num_channels = ARRAY_SIZE(ltc2305_channels),
+};
+
+static const struct ltc2309_chip_info ltc2309_chip_info = {
+ .name = "ltc2309",
+ .channels = ltc2309_channels,
+ .num_channels = ARRAY_SIZE(ltc2309_channels),
+};
+
static int ltc2309_read_raw_channel(struct ltc2309 *ltc2309,
unsigned long address, int *val)
{
@@ -158,6 +192,7 @@ static const struct iio_info ltc2309_info = {
static int ltc2309_probe(struct i2c_client *client)
{
+ const struct ltc2309_chip_info *chip_info;
struct iio_dev *indio_dev;
struct ltc2309 *ltc2309;
int ret;
@@ -167,13 +202,15 @@ static int ltc2309_probe(struct i2c_client *client)
return -ENOMEM;
ltc2309 = iio_priv(indio_dev);
+ chip_info = i2c_get_match_data(client);
+
ltc2309->dev = &indio_dev->dev;
ltc2309->client = client;
- indio_dev->name = "ltc2309";
+ indio_dev->name = chip_info->name;
indio_dev->modes = INDIO_DIRECT_MODE;
- indio_dev->channels = ltc2309_channels;
- indio_dev->num_channels = ARRAY_SIZE(ltc2309_channels);
+ indio_dev->channels = chip_info->channels;
+ indio_dev->num_channels = chip_info->num_channels;
indio_dev->info = <c2309_info;
ret = devm_regulator_get_enable_read_voltage(&client->dev, "vref");
@@ -189,13 +226,15 @@ static int ltc2309_probe(struct i2c_client *client)
}
static const struct of_device_id ltc2309_of_match[] = {
- { .compatible = "lltc,ltc2309" },
+ { .compatible = "lltc,ltc2305", .data = <c2305_chip_info },
+ { .compatible = "lltc,ltc2309", .data = <c2309_chip_info },
{ }
};
MODULE_DEVICE_TABLE(of, ltc2309_of_match);
static const struct i2c_device_id ltc2309_id[] = {
- { "ltc2309" },
+ { "ltc2305", (kernel_ulong_t)<c2305_chip_info },
+ { "ltc2309", (kernel_ulong_t)<c2309_chip_info },
{ }
};
MODULE_DEVICE_TABLE(i2c, ltc2309_id);
--
2.34.1
^ permalink raw reply related [flat|nested] 5+ messages in thread