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

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

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