Add support for the Linear Technology LTC2654 quad DAC family.
The LTC2654 is a 4-channel, 16-/12-bit DAC with SPI interface,
sharing the same 24-bit SPI protocol as the existing LTC2632/
LTC2634/LTC2636 devices supported by this driver.
Add support for the following variants:
- LTC2654L-16: 16-bit, 2.5V internal reference
- LTC2654L-12: 12-bit, 2.5V internal reference
- LTC2654H-16: 16-bit, 4.096V internal reference
- LTC2654H-12: 12-bit, 4.096V internal reference
Signed-off-by: David Marinovic <david.marinovic@pupin.rs>
---
drivers/iio/dac/ltc2632.c | 47 ++++++++++++++++++++++++++++++++++++---
1 file changed, 44 insertions(+), 3 deletions(-)
diff --git a/drivers/iio/dac/ltc2632.c b/drivers/iio/dac/ltc2632.c
index 105f939f7e54..05d3bf65399f 100644
--- a/drivers/iio/dac/ltc2632.c
+++ b/drivers/iio/dac/ltc2632.c
@@ -67,6 +67,10 @@ enum ltc2632_supported_device_ids {
ID_LTC2636H12,
ID_LTC2636H10,
ID_LTC2636H8,
+ ID_LTC2654L16,
+ ID_LTC2654L12,
+ ID_LTC2654H16,
+ ID_LTC2654H12
};
static int ltc2632_spi_write(struct spi_device *spi,
@@ -79,8 +83,8 @@ static int ltc2632_spi_write(struct spi_device *spi,
* The input shift register is 24 bits wide.
* The next four are the command bits, C3 to C0,
* followed by the 4-bit DAC address, A3 to A0, and then the
- * 12-, 10-, 8-bit data-word. The data-word comprises the 12-,
- * 10-, 8-bit input code followed by 4, 6, or 8 don't care bits.
+ * 16-, 12-, 10-, 8-bit data-word. The data-word comprises the
+ * 16-, 12-, 10-, 8-bit input code followed by 0, 4, 6, or 8
don't care bits.
*/
data = (cmd << 20) | (addr << 16) | (val << shift);
put_unaligned_be24(data, &msg[0]);
@@ -206,6 +210,7 @@ static const struct iio_chan_spec_ext_info
ltc2632_ext_info[] = {
LTC2632_CHANNEL(7, _bits), \
}
+static DECLARE_LTC2632_CHANNELS(ltc2632x16, 16);
static DECLARE_LTC2632_CHANNELS(ltc2632x12, 12);
static DECLARE_LTC2632_CHANNELS(ltc2632x10, 10);
static DECLARE_LTC2632_CHANNELS(ltc2632x8, 8);
@@ -301,6 +306,26 @@ static const struct ltc2632_chip_info
ltc2632_chip_info_tbl[] = {
.num_channels = 8,
.vref_mv = 4096,
},
+ [ID_LTC2654L16] = {
+ .channels = ltc2632x16_channels,
+ .num_channels = 4,
+ .vref_mv = 2500,
+ },
+ [ID_LTC2654L12] = {
+ .channels = ltc2632x12_channels,
+ .num_channels = 4,
+ .vref_mv = 2500,
+ },
+ [ID_LTC2654H16] = {
+ .channels = ltc2632x16_channels,
+ .num_channels = 4,
+ .vref_mv = 4096,
+ },
+ [ID_LTC2654H12] = {
+ .channels = ltc2632x12_channels,
+ .num_channels = 4,
+ .vref_mv = 4096,
+ },
};
static int ltc2632_probe(struct spi_device *spi)
@@ -372,6 +397,10 @@ static const struct spi_device_id ltc2632_id[] = {
{ "ltc2636-h12",
(kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2636H12] },
{ "ltc2636-h10",
(kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2636H10] },
{ "ltc2636-h8",
(kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2636H8] },
+ { "ltc2654-l16",
(kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2654L16] },
+ { "ltc2654-l12",
(kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2654L12] },
+ { "ltc2654-h16",
(kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2654H16] },
+ { "ltc2654-h12",
(kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2654H12] },
{ }
};
MODULE_DEVICE_TABLE(spi, ltc2632_id);
@@ -431,6 +460,18 @@ static const struct of_device_id ltc2632_of_match[]
= {
}, {
.compatible = "lltc,ltc2636-h8",
.data = <c2632_chip_info_tbl[ID_LTC2636H8]
+ }, {
+ .compatible = "lltc,ltc2654-l16",
+ .data = <c2632_chip_info_tbl[ID_LTC2654L16]
+ }, {
+ .compatible = "lltc,ltc2654-l12",
+ .data = <c2632_chip_info_tbl[ID_LTC2654L12]
+ }, {
+ .compatible = "lltc,ltc2654-h16",
+ .data = <c2632_chip_info_tbl[ID_LTC2654H16]
+ }, {
+ .compatible = "lltc,ltc2654-h12",
+ .data = <c2632_chip_info_tbl[ID_LTC2654H12]
},
{ }
};
@@ -447,5 +488,5 @@ static struct spi_driver ltc2632_driver = {
module_spi_driver(ltc2632_driver);
MODULE_AUTHOR("Maxime Roussin-Belanger
<maxime.roussinbelanger@gmail.com>");
-MODULE_DESCRIPTION("LTC2632 DAC SPI driver");
+MODULE_DESCRIPTION("LTC2632/LTC2654 DAC SPI driver");
MODULE_LICENSE("GPL v2");
--
2.50.1
-------- Original Message --------
Subject: [PATCH 0/2] iio: dac: ltc2632: add support for LTC2654 DAC
family
Date: 10.03.2026 16:27
From: David Marinović <david.marinovic@pupin.rs>
To: jic23@kernel.org
This patch series adds support for the Linear Technology LTC2654
quad DAC family to the existing ltc2632 driver.
The LTC2654 shares the same 24-bit SPI protocol as the existing
LTC2632/2634/2636 devices, requiring minimal additions to the
driver.
The LTC2654L-16 variant has been tested on a Phytec phyCORE-STM32MP1
board with the DAC connected via SPI1. The driver probes successfully
and all 4 channels are accessible via the IIO sysfs interface.
Patch 1 adds the driver support.
Patch 2 updates the DT bindings documentation.
David Marinovic (2):
iio: dac: ltc2632: add support for LTC2654 DAC family
dt-bindings: iio: dac: ltc2632: add LTC2654 compatible strings
Signed-off-by: David Marinovic <david.marinovic@pupin.rs>
On Tue, Mar 10, 2026 at 04:29:48PM +0100, David Marinović wrote:
>
> Add support for the Linear Technology LTC2654 quad DAC family.
> The LTC2654 is a 4-channel, 16-/12-bit DAC with SPI interface,
> sharing the same 24-bit SPI protocol as the existing LTC2632/
> LTC2634/LTC2636 devices supported by this driver.
>
> Add support for the following variants:
> - LTC2654L-16: 16-bit, 2.5V internal reference
> - LTC2654L-12: 12-bit, 2.5V internal reference
> - LTC2654H-16: 16-bit, 4.096V internal reference
> - LTC2654H-12: 12-bit, 4.096V internal reference
...
> enum ltc2632_supported_device_ids {
> ID_LTC2636H12,
> ID_LTC2636H10,
> ID_LTC2636H8,
> + ID_LTC2654L16,
> + ID_LTC2654L12,
> + ID_LTC2654H16,
> + ID_LTC2654H12
You see how nicely the new IDs landed here, but after you it will require an
unneeded churn.
> };
...
> static const struct spi_device_id ltc2632_id[] = {
> { "ltc2636-h12",
> (kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2636H12] },
> { "ltc2636-h10",
> (kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2636H10] },
> { "ltc2636-h8", (kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2636H8]
> },
> + { "ltc2654-l16",
> (kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2654L16] },
> + { "ltc2654-l12",
> (kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2654L12] },
> + { "ltc2654-h16",
> (kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2654H16] },
> + { "ltc2654-h12",
> (kernel_ulong_t)<c2632_chip_info_tbl[ID_LTC2654H12] },
> { }
Can we have a refactor patch to drop that enum and use separate chip_info
static objects?
> };
...
> static const struct of_device_id ltc2632_of_match[] = {
> }, {
> .compatible = "lltc,ltc2636-h8",
> .data = <c2632_chip_info_tbl[ID_LTC2636H8]
> + }, {
> + .compatible = "lltc,ltc2654-l16",
> + .data = <c2632_chip_info_tbl[ID_LTC2654L16]
> + }, {
> + .compatible = "lltc,ltc2654-l12",
> + .data = <c2632_chip_info_tbl[ID_LTC2654L12]
> + }, {
> + .compatible = "lltc,ltc2654-h16",
> + .data = <c2632_chip_info_tbl[ID_LTC2654H16]
> + }, {
> + .compatible = "lltc,ltc2654-h12",
> + .data = <c2632_chip_info_tbl[ID_LTC2654H12]
> },
Ditto.
> { }
> };
...
> Subject: [PATCH 0/2] iio: dac: ltc2632: add support for LTC2654 DAC family
> Date: 10.03.2026 16:27
> From: David Marinović <david.marinovic@pupin.rs>
> To: jic23@kernel.org
>
> This patch series adds support for the Linear Technology LTC2654
> quad DAC family to the existing ltc2632 driver.
Huh?!
--
With Best Regards,
Andy Shevchenko
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