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Date:   Sun, 14 May 2017 16:44:44 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Jan Kiszka <jan.kiszka@...mens.com>
Cc:     linux-iio@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Sascha Weisenberger <sascha.weisenberger@...mens.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Rob Herring <robh@...nel.org>
Subject: Re: [PATCH v5] iio: adc: Add support for TI ADC108S102 and ADC128S102

On 08/05/17 10:00, Andy Shevchenko wrote:
> 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@...tex.com>
>> Ported from Intel Galileo Gen2 BSP to Intel Yocto kernel:
>> Todor Minchev <todor@...chev.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@...ux.intel.com>
Giving credit for reviews is important for all the usual reasons!
Thanks for your hard work.

Jonathan
> 
>> Signed-off-by: Jan Kiszka <jan.kiszka@...mens.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@...tex.com>");
>> +MODULE_DESCRIPTION("Texas Instruments ADC108S102 and ADC128S102
>> driver");
>> +MODULE_LICENSE("GPL v2");
> 

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