Re: [PATCH v5] iio: adc: Add support for TI ADC108S102 and ADC128S102

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Mon, 2017-05-08 at 10:46 +0200, Jan Kiszka wrote:
> This is an upstream port of an IIO driver for the TI ADC108S102 and
> ADC128S102. The former can be found on the Intel Galileo Gen2 and the
> Siemens SIMATIC IOT2000. For those boards, ACPI-based enumeration is
> included.
> 
> Due to the lack of regulators under ACPI, we hard-code the voltage
> provided to the VA pin of the ADC to 5 V, the value used on Galileo
> and
> IOT2000. For DT usage, the regulator "vref-supply" provides this
> information. Note that DT usage has not been tested.
> 
> Original author: Bogdan Pricop <bogdan.pricop@emutex.com>
> Ported from Intel Galileo Gen2 BSP to Intel Yocto kernel:
> Todor Minchev <todor@minchev.co.uk>.
> 

Okay, it looks like it most what we can do right now about regulator
framework appearance in this driver.

FWIW:
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
> 
> Changes in v5:
>  - refactor error handling in adc108s102_read_raw
>  - removed no longer needed checks before regulator_disable
>    (v3 left-over)
> 
>  .../devicetree/bindings/iio/adc/ti-adc108s102.txt  |  18 ++
>  drivers/iio/adc/Kconfig                            |  12 +
>  drivers/iio/adc/Makefile                           |   1 +
>  drivers/iio/adc/ti-adc108s102.c                    | 342
> +++++++++++++++++++++
>  4 files changed, 373 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/ti-
> adc108s102.txt
>  create mode 100644 drivers/iio/adc/ti-adc108s102.c
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/ti-
> adc108s102.txt b/Documentation/devicetree/bindings/iio/adc/ti-
> adc108s102.txt
> new file mode 100644
> index 000000000000..bbbbb4a9f58f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/ti-adc108s102.txt
> @@ -0,0 +1,18 @@
> +* Texas Instruments' ADC108S102 and ADC128S102 ADC chip
> +
> +Required properties:
> + - compatible: Should be "ti,adc108s102"
> + - reg: spi chip select number for the device
> + - vref-supply: The regulator supply for ADC reference voltage
> +
> +Recommended properties:
> + - spi-max-frequency: Definition as per
> +		Documentation/devicetree/bindings/spi/spi-bus.txt
> +
> +Example:
> +adc@0 {
> +	compatible = "ti,adc108s102";
> +	reg = <0>;
> +	vref-supply = <&vdd_supply>;
> +	spi-max-frequency = <1000000>;
> +};
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index dedae7adbce9..8b7dae5604f2 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -572,6 +572,18 @@ config TI_ADC12138
>  	  This driver can also be built as a module. If so, the
> module will be
>  	  called ti-adc12138.
>  
> +config TI_ADC108S102
> +	tristate "Texas Instruments ADC108S102 and ADC128S102 driver"
> +	depends on SPI
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	help
> +	  Say yes here to build support for Texas Instruments
> ADC108S102 and
> +	  ADC128S102 ADC.
> +
> +	  To compile this driver as a module, choose M here: the
> module will
> +	  be called ti-adc108s102.
> +
>  config TI_ADC128S052
>  	tristate "Texas Instruments ADC128S052/ADC122S021/ADC124S021"
>  	depends on SPI
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index d0012620cd1c..e6c20fe3d4eb 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -52,6 +52,7 @@ obj-$(CONFIG_STM32_ADC) += stm32-adc.o
>  obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
>  obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
>  obj-$(CONFIG_TI_ADC12138) += ti-adc12138.o
> +obj-$(CONFIG_TI_ADC108S102) += ti-adc108s102.o
>  obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
>  obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
>  obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
> diff --git a/drivers/iio/adc/ti-adc108s102.c b/drivers/iio/adc/ti-
> adc108s102.c
> new file mode 100644
> index 000000000000..bdf3254619a3
> --- /dev/null
> +++ b/drivers/iio/adc/ti-adc108s102.c
> @@ -0,0 +1,342 @@
> +/*
> + * TI ADC108S102 SPI ADC driver
> + *
> + * Copyright (c) 2013-2015 Intel Corporation.
> + * Copyright (c) 2017 Siemens AG
> + *
> + * This program is free software; you can redistribute it and/or
> modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but
> WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
> or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
> License for
> + * more details.
> + *
> + * This IIO device driver is designed to work with the following
> + * analog to digital converters from Texas Instruments:
> + *  ADC108S102
> + *  ADC128S102
> + * The communication with ADC chip is via the SPI bus (mode 3).
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/types.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/property.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +
> +/*
> + * In case of ACPI, we use the hard-wired 5000 mV of the Galileo and
> IOT2000
> + * boards as default for the reference pin VA. Device tree users
> encode that
> + * via the vref-supply regulator.
> + */
> +#define ADC108S102_VA_MV_ACPI_DEFAULT	5000
> +
> +/*
> + * Defining the ADC resolution being 12 bits, we can use the same
> driver for
> + * both ADC108S102 (10 bits resolution) and ADC128S102 (12 bits
> resolution)
> + * chips. The ADC108S102 effectively returns a 12-bit result with the
> 2
> + * least-significant bits unset.
> + */
> +#define ADC108S102_BITS		12
> +#define ADC108S102_MAX_CHANNELS	8
> +
> +/*
> + * 16-bit SPI command format:
> + *   [15:14] Ignored
> + *   [13:11] 3-bit channel address
> + *   [10:0]  Ignored
> + */
> +#define ADC108S102_CMD(ch)		((u16)(ch) << 11)
> +
> +/*
> + * 16-bit SPI response format:
> + *   [15:12] Zeros
> + *   [11:0]  12-bit ADC sample (for ADC108S102, [1:0] will always be
> 0).
> + */
> +#define ADC108S102_RES_DATA(res)	((u16)res & GENMASK(11, 0))
> +
> +struct adc108s102_state {
> +	struct spi_device		*spi;
> +	struct regulator		*reg;
> +	u32				va_millivolt;
> +	/* SPI transfer used by triggered buffer handler*/
> +	struct spi_transfer		ring_xfer;
> +	/* SPI transfer used by direct scan */
> +	struct spi_transfer		scan_single_xfer;
> +	/* SPI message used by ring_xfer SPI transfer */
> +	struct spi_message		ring_msg;
> +	/* SPI message used by scan_single_xfer SPI transfer */
> +	struct spi_message		scan_single_msg;
> +
> +	/*
> +	 * SPI message buffers:
> +	 *  tx_buf: |C0|C1|C2|C3|C4|C5|C6|C7|XX|
> +	 *  rx_buf: |XX|R0|R1|R2|R3|R4|R5|R6|R7|tt|tt|tt|tt|
> +	 *
> +	 *  tx_buf: 8 channel read commands, plus 1 dummy command
> +	 *  rx_buf: 1 dummy response, 8 channel responses, plus 64-
> bit timestamp
> +	 */
> +	__be16				rx_buf[13]
> ____cacheline_aligned;
> +	__be16				tx_buf[9]
> ____cacheline_aligned;
> +};
> +
> +#define ADC108S102_V_CHAN(index)					
> \
> +	{								
> \
> +		.type = IIO_VOLTAGE,					
> \
> +		.indexed = 1,						
> \
> +		.channel = index,					
> \
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	
> 	\
> +			BIT(IIO_CHAN_INFO_SCALE),			
> \
> +		.address = index,					
> \
> +		.scan_index = index,					
> \
> +		.scan_type = {					
> 	\
> +			.sign = 'u',					
> \
> +			.realbits = ADC108S102_BITS,			
> \
> +			.storagebits = 16,				
> \
> +			.endianness = IIO_BE,				
> \
> +		},							
> \
> +	}
> +
> +static const struct iio_chan_spec adc108s102_channels[] = {
> +	ADC108S102_V_CHAN(0),
> +	ADC108S102_V_CHAN(1),
> +	ADC108S102_V_CHAN(2),
> +	ADC108S102_V_CHAN(3),
> +	ADC108S102_V_CHAN(4),
> +	ADC108S102_V_CHAN(5),
> +	ADC108S102_V_CHAN(6),
> +	ADC108S102_V_CHAN(7),
> +	IIO_CHAN_SOFT_TIMESTAMP(8),
> +};
> +
> +static int adc108s102_update_scan_mode(struct iio_dev *indio_dev,
> +		unsigned long const *active_scan_mask)
> +{
> +	struct adc108s102_state *st = iio_priv(indio_dev);
> +	unsigned int bit, cmds;
> +
> +	/*
> +	 * Fill in the first x shorts of tx_buf with the number of
> channels
> +	 * enabled for sampling by the triggered buffer.
> +	 */
> +	cmds = 0;
> +	for_each_set_bit(bit, active_scan_mask,
> ADC108S102_MAX_CHANNELS)
> +		st->tx_buf[cmds++] =
> cpu_to_be16(ADC108S102_CMD(bit));
> +
> +	/* One dummy command added, to clock in the last response */
> +	st->tx_buf[cmds++] = 0x00;
> +
> +	/* build SPI ring message */
> +	st->ring_xfer.tx_buf = &st->tx_buf[0];
> +	st->ring_xfer.rx_buf = &st->rx_buf[0];
> +	st->ring_xfer.len = cmds * sizeof(st->tx_buf[0]);
> +
> +	spi_message_init_with_transfers(&st->ring_msg, &st-
> >ring_xfer, 1);
> +
> +	return 0;
> +}
> +
> +static irqreturn_t adc108s102_trigger_handler(int irq, void *p)
> +{
> +	struct iio_poll_func *pf = p;
> +	struct iio_dev *indio_dev = pf->indio_dev;
> +	struct adc108s102_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	ret = spi_sync(st->spi, &st->ring_msg);
> +	if (ret < 0)
> +		goto out_notify;
> +
> +	/* Skip the dummy response in the first slot */
> +	iio_push_to_buffers_with_timestamp(indio_dev,
> +					   (u8 *)&st->rx_buf[1],
> +					   iio_get_time_ns(indio_dev)
> );
> +
> +out_notify:
> +	iio_trigger_notify_done(indio_dev->trig);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int adc108s102_scan_direct(struct adc108s102_state *st,
> unsigned int ch)
> +{
> +	int ret;
> +
> +	st->tx_buf[0] = cpu_to_be16(ADC108S102_CMD(ch));
> +	ret = spi_sync(st->spi, &st->scan_single_msg);
> +	if (ret)
> +		return ret;
> +
> +	/* Skip the dummy response in the first slot */
> +	return be16_to_cpu(st->rx_buf[1]);
> +}
> +
> +static int adc108s102_read_raw(struct iio_dev *indio_dev,
> +			       struct iio_chan_spec const *chan,
> +			       int *val, int *val2, long m)
> +{
> +	struct adc108s102_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (m) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = iio_device_claim_direct_mode(indio_dev);
> +		if (ret)
> +			return ret;
> +
> +		ret = adc108s102_scan_direct(st, chan->address);
> +
> +		iio_device_release_direct_mode(indio_dev);
> +
> +		if (ret < 0)
> +			return ret;
> +
> +		*val = ADC108S102_RES_DATA(ret);
> +
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		if (chan->type != IIO_VOLTAGE)
> +			break;
> +
> +		*val = st->va_millivolt;
> +		*val2 = chan->scan_type.realbits;
> +
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	default:
> +		break;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info adc108s102_info = {
> +	.read_raw		= &adc108s102_read_raw,
> +	.update_scan_mode	= &adc108s102_update_scan_mode,
> +	.driver_module		= THIS_MODULE,
> +};
> +
> +static int adc108s102_probe(struct spi_device *spi)
> +{
> +	struct adc108s102_state *st;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +
> +	if (ACPI_COMPANION(&spi->dev)) {
> +		st->va_millivolt = ADC108S102_VA_MV_ACPI_DEFAULT;
> +	} else {
> +		st->reg = devm_regulator_get(&spi->dev, "vref");
> +		if (IS_ERR(st->reg))
> +			return PTR_ERR(st->reg);
> +
> +		ret = regulator_enable(st->reg);
> +		if (ret < 0) {
> +			dev_err(&spi->dev, "Cannot enable vref
> regulator\n");
> +			return ret;
> +		}
> +
> +		ret = regulator_get_voltage(st->reg);
> +		if (ret < 0) {
> +			dev_err(&spi->dev, "vref get voltage
> failed\n");
> +			return ret;
> +		}
> +
> +		st->va_millivolt = ret / 1000;
> +	}
> +
> +	spi_set_drvdata(spi, indio_dev);
> +	st->spi = spi;
> +
> +	indio_dev->name = spi->modalias;
> +	indio_dev->dev.parent = &spi->dev;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = adc108s102_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(adc108s102_channels);
> +	indio_dev->info = &adc108s102_info;
> +
> +	/* Setup default message */
> +	st->scan_single_xfer.tx_buf = st->tx_buf;
> +	st->scan_single_xfer.rx_buf = st->rx_buf;
> +	st->scan_single_xfer.len = 2 * sizeof(st->tx_buf[0]);
> +
> +	spi_message_init_with_transfers(&st->scan_single_msg,
> +					&st->scan_single_xfer, 1);
> +
> +	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
> NULL,
> +			&adc108s102_trigger_handler, NULL);
> +	if (ret)
> +		goto error_disable_reg;
> +
> +	ret = devm_iio_device_register(&spi->dev, indio_dev);
> +	if (ret) {
> +		dev_err(&spi->dev, "Failed to register IIO
> device\n");
> +		goto error_disable_reg;
> +	}
> +	return 0;
> +
> +error_disable_reg:
> +	regulator_disable(st->reg);
> +
> +	return ret;
> +}
> +
> +static int adc108s102_remove(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +	struct adc108s102_state *st = iio_priv(indio_dev);
> +
> +	regulator_disable(st->reg);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id adc108s102_of_match[] = {
> +	{ .compatible = "ti,adc108s102" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, adc108s102_of_match);
> +#endif
> +
> +#ifdef CONFIG_ACPI
> +static const struct acpi_device_id adc108s102_acpi_ids[] = {
> +	{ "INT3495", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(acpi, adc108s102_acpi_ids);
> +#endif
> +
> +static const struct spi_device_id adc108s102_id[] = {
> +	{ "adc108s102", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(spi, adc108s102_id);
> +
> +static struct spi_driver adc108s102_driver = {
> +	.driver = {
> +		.name   = "adc108s102",
> +		.of_match_table = of_match_ptr(adc108s102_of_match),
> +		.acpi_match_table = ACPI_PTR(adc108s102_acpi_ids),
> +	},
> +	.probe		= adc108s102_probe,
> +	.remove		= adc108s102_remove,
> +	.id_table	= adc108s102_id,
> +};
> +module_spi_driver(adc108s102_driver);
> +
> +MODULE_AUTHOR("Bogdan Pricop <bogdan.pricop@emutex.com>");
> +MODULE_DESCRIPTION("Texas Instruments ADC108S102 and ADC128S102
> driver");
> +MODULE_LICENSE("GPL v2");

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy