Re: [PATCH 1/1] iio adc: add driver for Texas Instruments TLA2528 adc

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Mon,  2 Aug 2021 15:04:41 +0200
Rodolfo Giometti <giometti@enneenne.com> wrote:

> This adds a new driver for the TI TLA2528 ADC chip.
> 
> Signed-off-by: Rodolfo Giometti <giometti@enneenne.com>
Hi Rodolfo,

Comments inline,

Thanks,

Jonathan

> ---
>  drivers/iio/adc/Kconfig      |  10 ++
>  drivers/iio/adc/Makefile     |   1 +
>  drivers/iio/adc/ti-tla2528.c | 247 +++++++++++++++++++++++++++++++++++
>  3 files changed, 258 insertions(+)
>  create mode 100644 drivers/iio/adc/ti-tla2528.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index db0c8fb60515..f42e6d84c8f3 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -1178,6 +1178,16 @@ config TI_AM335X_ADC
>  	  To compile this driver as a module, choose M here: the module will be
>  	  called ti_am335x_adc.
>  
> +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 f70d877c555a..0bf287672838 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -105,6 +105,7 @@ obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
>  obj-$(CONFIG_TI_ADS124S08) += ti-ads124s08.o
>  obj-$(CONFIG_TI_ADS131E08) += ti-ads131e08.o
>  obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.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..5c362f846bae
> --- /dev/null
> +++ b/drivers/iio/adc/ti-tla2528.c
> @@ -0,0 +1,247 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for Texas Instruments TLA2528 ADC
> + *
> + * Copyright (C) 2020-2021 Rodolfo Giometti <giometti@enneenne.com>
> + */
> +
> +#include <linux/module.h>

Alphabetical order preferred, but fine to group the iio ones separately.

> +#include <linux/i2c.h>
> +#include <linux/delay.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/of.h>

Include mod_devicetable.h instead of of.h

> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>

I don't think you are using anything from iio/sysfs.h

> +
> +#define TLA2528_OP_READ_REG		0x10
> +#define TLA2528_OP_WRITE_REG		0x08
> +
> +#define TLA2528_GENERAL_CFG		0x01

I suggest using naming to make ti celar which of these is a
field, and which is a register address.  Given _REG is already
in use for something else perhaps
TLA2528_GENERAL_CFG_ADR etc?

It makes it easier to read the resulting code.

> +#define TLA2528_GENERAL_CFG_CNVST	BIT(3)
> +#define TLA2528_DATA_CFG		0x02
> +#define TLA2528_DATA_CFG_APPEND_STATUS	BIT(4)

Hmm. Datasheet oddly describes this one bit as being in a 2 bit field.
Guessing that's a typo and bit 5 is reserved.

> +#define TLA2528_DATA_CFG_FIX_PAT	BIT(7)
> +#define TLA2528_PIN_CFG			0x05
> +#define TLA2528_SEQUENCE_CFG		0x10
> +#define TLA2528_CHANNEL_SEL		0x11
> +
> +struct tla2528_st {
> +	struct i2c_client *client;
> +	struct regulator *ref;
> +
> +	u8 last_read_channel;
> +};
> +
> +static s32 i2c_smbus_read_sample(const struct i2c_client *client)
> +{
> +	struct i2c_msg msg[1];
> +	u8 data[2];

Make this the actual type which seems to be __be16 from the code
below.

> +	int ret;
> +
> +	msg[0].addr = client->addr;
> +	msg[0].flags = I2C_M_RD;
> +	msg[0].buf = (u8 *) &data;

No need for cast here, but irrelevant anyway as the code will be gone
if you use i2c_master_recv()

> +	msg[0].len = 2;
> +
> +	ret = i2c_transfer(client->adapter, msg, 1);

i2c_master_recv()

> +	if (ret < 0)
> +		return ret;
> +
> +	return le16_to_cpu(data[1] | (data[0] << 8));
This doesn't make any sense as the manual shifting
is converting from big endian to whatever the cpu is...

	return be16_to_cpup(data); is probably what is intended.

> +}
> +
> +static s32 i2c_smbus_write_reg(const struct i2c_client *client, u8 reg, u8 val)

This naming is odd given these are not generic functions...

> +{
> +	struct i2c_msg msg[1];
> +	u8 cmd[3] = {TLA2528_OP_WRITE_REG, reg, val};
> +
> +	msg[0].addr = client->addr;
> +	msg[0].flags = 0;
> +	msg[0].buf = cmd;
> +	msg[0].len = 3;
> +
> +	return i2c_transfer(client->adapter, msg, 1);
i2c_master_send() and have this return an int.

> +}
> +
> +static int tla2528_read(struct tla2528_st *st, u8 channel, int *val)
> +{
> +	struct i2c_client *client = st->client;
> +	int ret;
> +
> +	if (channel != st->last_read_channel) {
> +		ret = i2c_smbus_write_reg(st->client,
> +					TLA2528_CHANNEL_SEL, channel);
> +		if (ret < 0)
> +			return ret;
> +
> +		st->last_read_channel = channel;
> +	}
> +
> +	/* Read ADC data (2 bytes) */
> +	ret = i2c_smbus_read_sample(client);
> +	if (ret < 0)  {
> +		dev_err(&client->dev, "i2c_master_recv failed\n");
> +		return ret;
> +	}
> +	*val = ret >> 4;
> +
> +	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_st *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&indio_dev->mlock);
> +		ret = tla2528_read(st, chan->channel, val);
> +		mutex_unlock(&indio_dev->mlock);
> +		if (ret < 0)
> +			return ret;
> +
> +		return IIO_VAL_INT;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		ret = regulator_get_voltage(st->ref);
> +		if (ret < 0)
> +			return ret;
> +
> +		*val = ret / 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,
> +			 const struct i2c_device_id *id)
> +{
> +	struct iio_dev *indio_dev;
> +	struct tla2528_st *st;
> +	int ret;
> +
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
> +				     I2C_FUNC_SMBUS_WRITE_BYTE))
> +		return -EOPNOTSUPP;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +	i2c_set_clientdata(client, indio_dev);
> +	st->client = client;
> +
> +	indio_dev->name = id->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);
> +
> +	st->ref = devm_regulator_get(&client->dev, "vref");
> +	if (IS_ERR(st->ref))
> +		return PTR_ERR(st->ref);
> +
> +	ret = regulator_enable(st->ref);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Set all inputs as analog */
> +	ret = i2c_smbus_write_reg(st->client, TLA2528_PIN_CFG, 0x00);
> +	if (ret < 0)
> +		goto err_regulator_disable;
> +
> +	ret = i2c_smbus_write_reg(st->client, TLA2528_DATA_CFG,
> +				  TLA2528_DATA_CFG_APPEND_STATUS);
> +	if (ret < 0)
> +		goto err_regulator_disable;
> +
> +	/* Set manual mode */
> +	ret = i2c_smbus_write_reg(st->client, TLA2528_SEQUENCE_CFG, 0x00);
> +	if (ret < 0)
> +		goto err_regulator_disable;
> +
> +	/* Init private data */
> +	st->last_read_channel = ~0;
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret < 0)
> +		goto err_regulator_disable;
> +
> +	return 0;
> +
> +err_regulator_disable:
> +	regulator_disable(st->ref);
> +
> +	return ret;
> +}
> +
> +static int tla2528_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct tla2528_st *st = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +	regulator_disable(st->ref);
> +
> +	return 0;
> +}
> +
> +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,
> +	.remove = tla2528_remove,
> +	.id_table = tla2528_id,
> +};
> +module_i2c_driver(tla2528_driver);
> +
> +MODULE_AUTHOR("Rodolfo Giometti <giometti@enneenne.com>");
> +MODULE_DESCRIPTION("Texas Instruments TLA2528 ADC driver");
> +MODULE_LICENSE("GPL v2");