[PATCH v2 0/2] Add driver for the TI TLA2528 i2c ADC

[PATCH v2 0/2] Add driver for the TI TLA2528 i2c ADC

[Maxime Chevallier]

Hi everyone,

This is V2 for the TLA2528 ADC support, V1 was sent almost a year ago
and was already resurecting yet another older series from Rodolfo
Giometti [1]. Sorry for the slow iteration.

This V2 addresses the various comments that were made on V1, thanks
again to everyone involved in the first review round (Jonathan, Andy,
Matti and David)

This was tested on a custom board based on imx93, with a 3v3 ref supply.

Maxime  

[1] : https://lore.kernel.org/linux-iio/20210802130441.972978-1-giometti@enneenne.com/

V2:
  - Describe AVDD and DVDD in the bindings instead of vref.
  - Add gpio-controller
  - Allow describing individual ADC channels
  - Switch to regmap with caching
  - Reset the chip at probe time
  - Small cleanups following all the reviews
  - Moved MAINTAINERS to patch 1

V1: https://lore.kernel.org/linux-iio/20251223155534.220504-1-maxime.chevallier@bootlin.com/

Maxime Chevallier (2):
  dt-bindings: iio: adc: add Texas Instruments TLA2528
  iio: adc: add driver for Texas Instruments TLA2528 adc

 .../bindings/iio/adc/ti,tla2528.yaml          |  91 +++++++
 MAINTAINERS                                   |   7 +
 drivers/iio/adc/Kconfig                       |  12 +
 drivers/iio/adc/Makefile                      |   1 +
 drivers/iio/adc/ti-tla2528.c                  | 245 ++++++++++++++++++
 5 files changed, 356 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/ti,tla2528.yaml
 create mode 100644 drivers/iio/adc/ti-tla2528.c

-- 
2.56.0

[PATCH v2 1/2] dt-bindings: iio: adc: add Texas Instruments TLA2528

[Maxime Chevallier]

The TI TLA2528 is a simple 8-channel, 12-bit ADC and GPIO chip
accessible over i2c. The ADC part has an AVDD supply that doubles as a
reference.

As this chip can be used both for its ADC and GPIOs, let's allow
describing each ADC channel individually. If no ADC chan description is
represented, all channels will be exposed as analog inputs.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
 .../bindings/iio/adc/ti,tla2528.yaml          | 91 +++++++++++++++++++
 MAINTAINERS                                   |  6 ++
 2 files changed, 97 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/ti,tla2528.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/ti,tla2528.yaml b/Documentation/devicetree/bindings/iio/adc/ti,tla2528.yaml
new file mode 100644
index 000000000000..7a50a5026c1e
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/ti,tla2528.yaml
@@ -0,0 +1,91 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/ti,tla2528.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Texas Instruments TLA2528 8-channel 12-bit I2C ADC
+
+maintainers:
+  - Maxime Chevallier <maxime.chevallier@bootlin.com>
+
+description:
+  Each of the 8 input pins can be configured as an analog input, a digital
+  input or a digital output.
+
+properties:
+  compatible:
+    const: ti,tla2528
+
+  reg:
+    maxItems: 1
+
+  avdd-supply:
+    description: Analog supply, also used as the ADC reference voltage.
+
+  dvdd-supply: true
+
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 2
+
+  "#io-channel-cells":
+    const: 1
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+patternProperties:
+  "^channel@[0-7]$":
+    type: object
+    $ref: adc.yaml
+    description: Represents an analog input.
+
+    properties:
+      reg:
+        description: AIN pin number
+        minimum: 0
+        maximum: 7
+
+    required:
+      - reg
+
+    unevaluatedProperties: false
+
+required:
+  - compatible
+  - reg
+  - avdd-supply
+  - dvdd-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@17 {
+            compatible = "ti,tla2528";
+            reg = <0x17>;
+            avdd-supply = <&reg_adc_supply>;
+            dvdd-supply = <&reg_adc_supply>;
+            #io-channel-cells = <1>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            channel@0 {
+                reg = <0>;
+            };
+
+            channel@3 {
+                reg = <3>;
+            };
+        };
+    };
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 7a162e9bcab1..471585b29c19 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -27715,6 +27715,12 @@ 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
+
 TEXAS INSTRUMENTS' TMP117 TEMPERATURE SENSOR DRIVER
 M:	Puranjay Mohan <puranjay@kernel.org>
 L:	linux-iio@vger.kernel.org
-- 
2.56.0

[PATCH v2 2/2] iio: adc: add driver for Texas Instruments TLA2528 adc

[Maxime Chevallier]

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

This is a very simple driver, allowing reading raw values for each
channel. GPIO mode isn't supported for now, as well as buffered mode and
the 16-bit averaging mode.

Co-developed-by: Rodolfo Giometti <giometti@enneenne.com>
Signed-off-by: Rodolfo Giometti <giometti@enneenne.com>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
 MAINTAINERS                  |   1 +
 drivers/iio/adc/Kconfig      |  12 ++
 drivers/iio/adc/Makefile     |   1 +
 drivers/iio/adc/ti-tla2528.c | 245 +++++++++++++++++++++++++++++++++++
 4 files changed, 259 insertions(+)
 create mode 100644 drivers/iio/adc/ti-tla2528.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 471585b29c19..1ebb6418ab1f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -27720,6 +27720,7 @@ 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>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index a802d8ee4dd9..8633267d6056 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -2016,6 +2016,18 @@ 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
+	select REGMAP_I2C
+	select IIO_ADC_HELPER
+	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 9e82c21dbd37..b98cded4d0c7 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -171,6 +171,7 @@ 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..287e52dc9d6d
--- /dev/null
+++ b/drivers/iio/adc/ti-tla2528.c
@@ -0,0 +1,245 @@
+// 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/bits.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/types.h>
+#include <linux/units.h>
+
+#include <linux/iio/adc-helpers.h>
+#include <linux/iio/iio.h>
+
+#define TLA2528_OP_WRITE_REG		0x08
+#define TLA2528_OP_READ_REG		0x10
+
+#define TLA2528_SYSTEM_STATUS_ADR	0x00
+#define TLA2528_GENERAL_CFG_ADR		0x01
+#define TLA2528_GENERAL_CFG_RST		BIT(0)
+#define TLA2528_GPI_VALUE_ADR		0x0d
+#define TLA2528_CHANNEL_SEL_ADR		0x11
+#define TLA2528_CHANNEL_SEL_MANUAL_CHID	GENMASK(3, 0)
+#define TLA2528_AUTO_SEQ_CH_SEL_ADR	0x12
+
+#define TLA2528_NUM_CHANNELS		8
+
+struct tla2528 {
+	struct i2c_client *client;
+	struct regmap *regmap;
+	int vref_mv;
+
+	/* Protects manual channel selection */
+	struct mutex lock;
+};
+
+static bool tla2528_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case TLA2528_SYSTEM_STATUS_ADR:
+	case TLA2528_GENERAL_CFG_ADR:
+	case TLA2528_GPI_VALUE_ADR:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config tla2528_regmap_config = {
+	.reg_bits = 16,
+	.val_bits = 8,
+	.read_flag_mask = TLA2528_OP_READ_REG,
+	.write_flag_mask = TLA2528_OP_WRITE_REG,
+	.max_register = TLA2528_AUTO_SEQ_CH_SEL_ADR,
+	.volatile_reg = tla2528_volatile_reg,
+	.cache_type = REGCACHE_MAPLE,
+};
+
+static int tla2528_read_sample(const struct i2c_client *client)
+{
+	__be16 data;
+	int ret;
+
+	ret = i2c_master_recv(client, (char *)&data, sizeof(data));
+	if (ret < 0)
+		return ret;
+
+	return be16_to_cpu(data) >> 4;
+}
+
+static int tla2528_read(struct tla2528 *tla2528, u8 channel, int *val)
+{
+	int ret;
+
+	ret = regmap_update_bits(tla2528->regmap, TLA2528_CHANNEL_SEL_ADR,
+				 TLA2528_CHANNEL_SEL_MANUAL_CHID, channel);
+	if (ret)
+		return ret;
+
+	ret = tla2528_read_sample(tla2528->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_mv;
+		*val2 = 12;
+
+		return IIO_VAL_FRACTIONAL_LOG2;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+#define TLA2528_CHAN(chan) {					\
+	.type = IIO_VOLTAGE,					\
+	.channel = (chan),					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+	.indexed = 1,						\
+}
+
+static const struct iio_chan_spec tla2528_chan_template = TLA2528_CHAN(0);
+
+static const struct iio_chan_spec tla2528_channel[] = {
+	TLA2528_CHAN(0),
+	TLA2528_CHAN(1),
+	TLA2528_CHAN(2),
+	TLA2528_CHAN(3),
+	TLA2528_CHAN(4),
+	TLA2528_CHAN(5),
+	TLA2528_CHAN(6),
+	TLA2528_CHAN(7),
+};
+
+static const struct iio_info tla2528_info = {
+	.read_raw = tla2528_read_raw,
+};
+
+static int tla2528_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct iio_chan_spec *channels;
+	struct iio_dev *indio_dev;
+	struct tla2528 *tla2528;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -EOPNOTSUPP;
+
+	if (i2c_check_quirks(client->adapter, I2C_AQ_NO_CLK_STRETCH))
+		return dev_err_probe(dev, -EOPNOTSUPP,
+				     "adapter does not support clock stretching\n");
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*tla2528));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	tla2528 = iio_priv(indio_dev);
+	tla2528->client = client;
+
+	tla2528->regmap = devm_regmap_init_i2c(client, &tla2528_regmap_config);
+	if (IS_ERR(tla2528->regmap))
+		return PTR_ERR(tla2528->regmap);
+
+	ret = devm_mutex_init(dev, &tla2528->lock);
+	if (ret)
+		return ret;
+
+	ret = devm_regulator_get_enable(dev, "dvdd");
+	if (ret)
+		return ret;
+
+	ret = devm_regulator_get_enable_read_voltage(dev, "avdd");
+	if (ret < 0)
+		return ret;
+
+	tla2528->vref_mv = ret / (MICRO / MILLI);
+
+	ret = devm_iio_adc_device_alloc_chaninfo_se(dev, &tla2528_chan_template,
+						    TLA2528_NUM_CHANNELS - 1,
+						    &channels);
+	if (ret < 0 && ret != -ENOENT)
+		return ret;
+
+	if (ret == -ENOENT) {
+		indio_dev->channels = tla2528_channel;
+		indio_dev->num_channels = ARRAY_SIZE(tla2528_channel);
+	} else {
+		indio_dev->channels = channels;
+		indio_dev->num_channels = ret;
+	}
+
+	indio_dev->name = "tla2528";
+	indio_dev->info = &tla2528_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = regmap_write(tla2528->regmap, TLA2528_GENERAL_CFG_ADR,
+			   TLA2528_GENERAL_CFG_RST);
+	if (ret)
+		return ret;
+
+	fsleep(5 * USEC_PER_MSEC);
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct i2c_device_id tla2528_id[] = {
+	{ "tla2528" },
+	{ }
+};
+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");
+MODULE_IMPORT_NS("IIO_DRIVER");
-- 
2.56.0

Re: [PATCH v2 2/2] iio: adc: add driver for Texas Instruments TLA2528 adc

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] iio: adc: ti-tla2528: uninitialized stack read in tla2528_read_sample()
- [Low] iio: adc: ti-tla2528: positional initializer in struct i2c_device_id table
--

commit 25a176a55c9c7afc00ecb1f3b6cd5d101cdeee77
Author: Maxime Chevallier <maxime.chevallier@bootlin.com>

iio: adc: add driver for Texas Instruments TLA2528 adc

This commit adds an IIO ADC driver for the Texas Instruments TLA2528 8-channel
12-bit I2C ADC supporting raw channel reads.

> diff --git a/drivers/iio/adc/ti-tla2528.c b/drivers/iio/adc/ti-tla2528.c
> new file mode 100644
> index 0000000000000..287e52dc9d6d2
> --- /dev/null
> +++ b/drivers/iio/adc/ti-tla2528.c
> @@ -0,0 +1,245 @@

[ ... ]

> +static int tla2528_read_sample(const struct i2c_client *client)
> +{
> +	__be16 data;
> +	int ret;
> +
> +	ret = i2c_master_recv(client, (char *)&data, sizeof(data));
> +	if (ret < 0)
> +		return ret;
> +
> +	return be16_to_cpu(data) >> 4;
> +}

[Severity: Medium]
Can tla2528_read_sample() read uninitialized stack memory from data when
called via tla2528_read_raw() -> tla2528_read() -> tla2528_read_sample()?

i2c_master_recv() calls i2c_transfer_buffer_flags():

drivers/i2c/i2c-core-base.c:i2c_transfer_buffer_flags() {
	...
	ret = i2c_transfer(client->adapter, &msg, 1);

	/*
	 * If everything went ok (i.e. 1 msg transferred), return #bytes
	 * transferred, else error code.
	 */
	return (ret == 1) ? count : ret;
}

If the underlying I2C adapter returns 0 messages transferred from
i2c_transfer() without populating the receive buffer, i2c_master_recv()
returns 0. Because tla2528_read_sample() only checks for ret < 0, it will
proceed to shift and return the uninitialized stack variable data to
userspace.

Should this check if (ret != sizeof(data)) and return -EIO when a short read
occurs?

[ ... ]

> +static const struct i2c_device_id tla2528_id[] = {
> +	{ "tla2528" },
> +	{ }
> +};

[Severity: Low]
This isn't a bug, but should the new entry in tla2528_id in
drivers/iio/adc/ti-tla2528.c use a named initializer ({ .name = "tla2528" })
to follow the I2C subsystem convention?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261030164705.297354-1-maxime.chevallier@bootlin.com?part=2

Re: [PATCH v2 1/2] dt-bindings: iio: adc: add Texas Instruments TLA2528

[Conor Dooley]

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Acked-by: Conor Dooley <conor.dooley@microchip.com>
pw-bot: not-applicable

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