[PATCH 2/2] iio: adc: add driver for Texas Instruments TLA2528 adc

Maxime Chevallier
2025-12-23T15:55:54Z

This adds a new driver for the TI TLA2528 ADC chip. It ha 8 12-bit
channels, that can also be configured as 16-bit averaging channels.

Add a very simple driver for it, allowing reading raw values for each
channel.

Signed-off-by: Rodolfo Giometti <giometti@enneenne.com>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
MAINTAINERS | 7 ++
drivers/iio/adc/Kconfig | 10 ++
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/ti-tla2528.c | 209 +++++++++++++++++++++++++++++++++++
4 files changed, 227 insertions(+)
create mode 100644 drivers/iio/adc/ti-tla2528.c

diff --git a/MAINTAINERS b/MAINTAINERS
index dc731d37c8fe..5c382ae216c7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -25866,6 +25866,13 @@ F: include/dt-bindings/soc/ti,sci_pm_domain.h
F: include/linux/soc/ti/ti_sci_inta_msi.h
F: include/linux/soc/ti/ti_sci_protocol.h

+TEXAS INSTRUMENTS' TLA2528 ADC DRIVER
+M: Maxime Chevallier <maxime.chevallier@bootlin.com>
+L: linux-iio@vger.kernel.org
+S: Supported
+F: Documentation/devicetree/bindings/iio/adc/ti,tla2528.yaml
+F: drivers/iio/adc/ti-tla2528.c
+
TEXAS INSTRUMENTS' TMP117 TEMPERATURE SENSOR DRIVER
M: Puranjay Mohan <puranjay@kernel.org>
L: linux-iio@vger.kernel.org
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 58da8255525e..67376de410bf 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1803,6 +1803,16 @@ config TI_LMP92064
This driver can also be built as a module. If so, the module will be called
ti-lmp92064.

+config TI_TLA2528
+ tristate "Texas Instruments TLA2528 ADC driver"
+ depends on I2C
+ help
+ Say yes here to build support for Texas Instruments TLA2528
+ 12-Bit 8-Channel ADC.
+
+ To compile this driver as a module, choose M here: the module will be
+ called ti-tla2528.
+
config TI_TLC4541
tristate "Texas Instruments TLC4541 ADC driver"
depends on SPI
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 7cc8f9a12f76..941606defbf7 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -157,6 +157,7 @@ obj-$(CONFIG_TI_ADS8344) += ti-ads8344.o
obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
obj-$(CONFIG_TI_LMP92064) += ti-lmp92064.o
+obj-$(CONFIG_TI_TLA2528) += ti-tla2528.o
obj-$(CONFIG_TI_TLC4541) += ti-tlc4541.o
obj-$(CONFIG_TI_TSC2046) += ti-tsc2046.o
obj-$(CONFIG_TWL4030_MADC) += twl4030-madc.o
diff --git a/drivers/iio/adc/ti-tla2528.c b/drivers/iio/adc/ti-tla2528.c
new file mode 100644
index 000000000000..9c572e730ffb
--- /dev/null
+++ b/drivers/iio/adc/ti-tla2528.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for Texas Instruments TLA2528 ADC
+ *
+ * Copyright (C) 2020-2021 Rodolfo Giometti <giometti@enneenne.com>
+ * Copyright (C) 2025 Maxime Chevallier <maxime.chevallier@bootlin.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/regulator/consumer.h>
+
+#include <linux/iio/iio.h>
+
+#define TLA2528_OP_WRITE_REG 0x08
+
+#define TLA2528_DATA_CFG_ADR 0x02
+
+/* Datasheet says [5:4] sets the append status, but only bit 4 is used */
+#define TLA2528_DATA_CFG_APPEND_STATUS BIT(4)
+#define TLA2528_PIN_CFG_ADR 0x05
+#define TLA2528_SEQUENCE_CFG_ADR 0x10
+#define TLA2528_CHANNEL_SEL_ADR 0x11
+
+struct tla2528 {
+ struct i2c_client *client;
+ int vref_uv;
+
+ /* Protects manual channel selection, i.e. last_read_channel */
+ struct mutex lock;
+ u8 last_read_channel;
+};
+
+static s32 tla2528_write_reg(const struct i2c_client *client, u8 reg, u8 val)
+{
+ u8 data[3] = {TLA2528_OP_WRITE_REG, reg, val};
+ int ret;
+
+ ret = i2c_master_send(client, data, 3);
+
+ return ret < 0 ? ret : 0;
+}
+
+static int tla2528_read_sample(const struct i2c_client *client)
+{
+ __be16 data;
+ int ret;
+
+ ret = i2c_master_recv(client, (char *)&data, 2);
+ if (ret < 0)
+ return ret;
+
+ return be16_to_cpu(data) >> 4;
+}
+
+static int tla2528_read(struct tla2528 *tla2528, u8 channel, int *val)
+{
+ struct i2c_client *client = tla2528->client;
+ int ret;
+
+ if (channel != tla2528->last_read_channel) {
+ ret = tla2528_write_reg(client, TLA2528_CHANNEL_SEL_ADR, channel);
+ if (ret < 0)
+ return ret;
+
+ tla2528->last_read_channel = channel;
+ }
+
+ ret = tla2528_read_sample(client);
+ if (ret < 0)
+ return ret;
+
+ *val = ret;
+
+ return 0;
+}
+
+static int tla2528_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct tla2528 *tla2528 = iio_priv(indio_dev);
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ mutex_lock(&tla2528->lock);
+ ret = tla2528_read(tla2528, chan->channel, val);
+ mutex_unlock(&tla2528->lock);
+ if (ret < 0)
+ return ret;
+
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_SCALE:
+ *val = tla2528->vref_uv / 1000;
+ *val2 = 12;
+
+ return IIO_VAL_FRACTIONAL_LOG2;
+
+ default:
+ return -EINVAL;
+ }
+}
+
+#define TLA2528_CHAN(_chan, _name) { \
+ .type = IIO_VOLTAGE, \
+ .channel = (_chan), \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ .datasheet_name = _name, \
+ .indexed = 1, \
+}
+
+static const struct iio_chan_spec tla2528_channel[] = {
+ TLA2528_CHAN(0, "AIN0"),
+ TLA2528_CHAN(1, "AIN1"),
+ TLA2528_CHAN(2, "AIN2"),
+ TLA2528_CHAN(3, "AIN3"),
+ TLA2528_CHAN(4, "AIN4"),
+ TLA2528_CHAN(5, "AIN5"),
+ TLA2528_CHAN(6, "AIN6"),
+ TLA2528_CHAN(7, "AIN7"),
+};
+
+static const struct iio_info tla2528_info = {
+ .read_raw = tla2528_read_raw,
+};
+
+static int tla2528_probe(struct i2c_client *client)
+{
+ struct iio_dev *indio_dev;
+ struct tla2528 *tla2528;
+ int ret;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
+ I2C_FUNC_SMBUS_WRITE_WORD_DATA))
+ return -EOPNOTSUPP;
+
+ indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*tla2528));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ tla2528 = iio_priv(indio_dev);
+ i2c_set_clientdata(client, indio_dev);
+ tla2528->client = client;
+
+ indio_dev->name = client->name;
+ indio_dev->info = &tla2528_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = tla2528_channel;
+ indio_dev->num_channels = ARRAY_SIZE(tla2528_channel);
+
+ mutex_init(&tla2528->lock);
+
+ tla2528->vref_uv = devm_regulator_get_enable_read_voltage(&client->dev,
+ "vref");
+ if (tla2528->vref_uv < 0)
+ return tla2528->vref_uv;
+
+ /* Set all inputs as analog */
+ ret = tla2528_write_reg(tla2528->client, TLA2528_PIN_CFG_ADR, 0x00);
+ if (ret < 0)
+ return ret;
+
+ ret = tla2528_write_reg(tla2528->client, TLA2528_DATA_CFG_ADR,
+ TLA2528_DATA_CFG_APPEND_STATUS);
+ if (ret < 0)
+ return ret;
+
+ /* Set manual mode */
+ ret = tla2528_write_reg(tla2528->client, TLA2528_SEQUENCE_CFG_ADR, 0x00);
+ if (ret < 0)
+ return ret;
+
+ /* Init private data */
+ tla2528->last_read_channel = ~0;
+
+ return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id tla2528_id[] = {
+ { "tla2528", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, tla2528_id);
+
+static const struct of_device_id tla2528_of_match[] = {
+ { .compatible = "ti,tla2528", },
+ { },
+};
+MODULE_DEVICE_TABLE(of, tla2528_of_match);
+
+static struct i2c_driver tla2528_driver = {
+ .driver = {
+ .name = "tla2528",
+ .of_match_table = tla2528_of_match,
+ },
+ .probe = tla2528_probe,
+ .id_table = tla2528_id,
+};
+module_i2c_driver(tla2528_driver);
+
+MODULE_AUTHOR("Maxime Chevallier <maxime.chevallier@bootlin.com>");
+MODULE_AUTHOR("Rodolfo Giometti <giometti@enneenne.com>");
+MODULE_DESCRIPTION("Texas Instruments TLA2528 ADC driver");
+MODULE_LICENSE("GPL");
--
2.49.0