Date:   Tue, 25 Apr 2017 09:31:26 +0200 (CEST)
From:   Peter Meerwald-Stadler <pmeerw@...erw.net>
To:     Jan Kiszka <jan.kiszka@...mens.com>
cc:     Jonathan Cameron <jic23@...nel.org>, linux-iio@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Sascha Weisenberger <sascha.weisenberger@...mens.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH] iio: adc: Add support for TI ADC1x8s102


> 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.

comments below

naming: don't use placeholders, name after one of the supported chips and 
list them in Kconfig and the driver file

what is the difference between this chip and those supported 
by ti-adc084s021 which was proposed by Mårten Lindahl on April 21?

I think board-specific stuff should not go into the driver -> DT?
 
> Original author: Bogdan Pricop <bogdan.pricop@...tex.com>
> Ported from Intel Galileo Gen2 BSP to Intel Yocto kernel:
> Todor Minchev <todor@...chev.co.uk>.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
> ---
>  drivers/iio/adc/Kconfig                  |  12 +
>  drivers/iio/adc/Makefile                 |   1 +
>  drivers/iio/adc/ti-adc1x8s102.c          | 408 +++++++++++++++++++++++++++++++
>  include/linux/platform_data/adc1x8s102.h |  28 +++
>  4 files changed, 449 insertions(+)
>  create mode 100644 drivers/iio/adc/ti-adc1x8s102.c
>  create mode 100644 include/linux/platform_data/adc1x8s102.h
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index dedae7adbce9..edb7254a648c 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -582,6 +582,18 @@ config TI_ADC128S052
>  	  This driver can also be built as a module. If so, the module will be
>  	  called ti-adc128s052.
>  
> +config TI_ADC1x8S102
> +	tristate "Texas Instruments ADC1x8S102 driver"
> +	depends on SPI
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	help
> +	  Say yes here to build support for Texas Instruments ADC1x8S102 ADC.
> +	  Provides direct access via sysfs.

drop the 'direct access' statement

> +
> +	  To compile this driver as a module, choose M here: the module will
> +	  be called ti-adc1x8s102

end with .

> +
>  config TI_ADC161S626
>  	tristate "Texas Instruments ADC161S626 1-channel differential ADC"
>  	depends on SPI
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index d0012620cd1c..d5d913bc1263 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -53,6 +53,7 @@ obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
>  obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
>  obj-$(CONFIG_TI_ADC12138) += ti-adc12138.o
>  obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
> +obj-$(CONFIG_TI_ADC1x8S102) += ti-adc1x8s102.o
>  obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
>  obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
>  obj-$(CONFIG_TI_ADS7950) += ti-ads7950.o
> diff --git a/drivers/iio/adc/ti-adc1x8s102.c b/drivers/iio/adc/ti-adc1x8s102.c
> new file mode 100644
> index 000000000000..4f94c371489d
> --- /dev/null
> +++ b/drivers/iio/adc/ti-adc1x8s102.c
> @@ -0,0 +1,408 @@
> +/*
> + * TI ADC1x8S102 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 is designed to work with the following

is is

> + * analog to digital converters from Texas Instruments:
> + *  ADC108S102
> + *  ADC128S102
> + * The communication with ADC chip is via the SPI bus (mode 3).
> + */
> +
> +#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/spi/spi.h>
> +
> +#include <linux/platform_data/adc1x8s102.h>

who needs platform data these days :)

> +#include <linux/regulator/consumer.h>
> +
> +#include <linux/delay.h>
> +#include <linux/acpi.h>
> +#include <linux/property.h>
> +#include <linux/gpio.h>
> +
> +#include <linux/spi/pxa2xx_spi.h>

no, this shouldn't be here

> +
> +/*
> + * 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 ADC1x8S102_BITS		12
> +#define ADC1x8S102_MAX_CHANNELS	8
> +
> +/* 16-bit SPI command format:
> + *   [15:14] Ignored
> + *   [13:11] 3-bit channel address
> + *   [10:0]  Ignored
> + */
> +#define ADC1x8S102_CMD(ch)		(((ch) << (8)) << (3))

no need to put parenthesis around 8 and 3
why not shift by 11?

> +
> +/*
> + * 16-bit SPI response format:
> + *   [15:12] Zeros
> + *   [11:0]  12-bit ADC sample (for ADC108S102, [1:0] will always be 0).
> + */
> +#define ADC1x8S102_RES_DATA(res)	(res & ((1 << ADC1x8S102_BITS) - 1))

could use GENMASK()

> +
> +#define ADC1x8S102_GALILEO2_CS	8

this board-specific detail shouldn't be here

> +
> +struct adc1x8s102_state {
> +	struct spi_device		*spi;
> +	struct regulator		*reg;
> +	u16				ext_vin;

unit?

> +	/* 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:

not a proper multi-line comment

> +	 *  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];
> +};
> +
> +#define ADC1X8S102_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 = ADC1x8S102_BITS,			\

this should be different for the 128 and 108 part, shift missing

most drivers do shifting and don't use _SCALE for that purpose

> +			.storagebits = 16,				\
> +			.endianness = IIO_BE,				\
> +		},							\
> +	}
> +
> +static const struct iio_chan_spec adc1x8s102_channels[] = {
> +	ADC1X8S102_V_CHAN(0),
> +	ADC1X8S102_V_CHAN(1),
> +	ADC1X8S102_V_CHAN(2),
> +	ADC1X8S102_V_CHAN(3),
> +	ADC1X8S102_V_CHAN(4),
> +	ADC1X8S102_V_CHAN(5),
> +	ADC1X8S102_V_CHAN(6),
> +	ADC1X8S102_V_CHAN(7),
> +	IIO_CHAN_SOFT_TIMESTAMP(8),
> +};
> +
> +static int adc1x8s102_update_scan_mode(struct iio_dev *indio_dev,
> +		unsigned long const *active_scan_mask)
> +{
> +	struct adc1x8s102_state *st;
> +	int i, j;
> +
> +	st = iio_priv(indio_dev);
> +
> +	/* Fill in the first x shorts of tx_buf with the number of channels

not a multi-line comment

> +	 * enabled for sampling by the triggered buffer
> +	 */
> +	for (i = 0, j = 0; i < ADC1x8S102_MAX_CHANNELS; i++) {
> +		if (test_bit(i, active_scan_mask)) {
> +			st->tx_buf[j] = cpu_to_be16(ADC1x8S102_CMD(i));
> +			j++;
> +		}
> +	}
> +	/* One dummy command added, to clock in the last response */
> +	st->tx_buf[j] = 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 = (j + 1) * sizeof(__be16);
> +
> +	spi_message_init(&st->ring_msg);
> +	spi_message_add_tail(&st->ring_xfer, &st->ring_msg);
> +
> +	return 0;
> +}
> +
> +static irqreturn_t adc1x8s102_trigger_handler(int irq, void *p)
> +{
> +	struct iio_poll_func *pf = p;
> +	struct iio_dev *indio_dev;
> +	struct adc1x8s102_state *st;
> +	s64 time_ns = 0;

no need to initialize

> +	int b_sent;
> +
> +	indio_dev = pf->indio_dev;
> +	st = iio_priv(indio_dev);
> +
> +	b_sent = spi_sync(st->spi, &st->ring_msg);
> +	if (b_sent == 0) {
> +		if (indio_dev->scan_timestamp) {
> +			time_ns = iio_get_time_ns(indio_dev);
> +			memcpy((u8 *)st->rx_buf + st->ring_xfer.len, &time_ns,
> +			       sizeof(time_ns));
> +		}
> +
> +		/* Skip the dummy response in the first slot */
> +		iio_push_to_buffers(indio_dev, (u8 *)&st->rx_buf[1]);

iio_push_to_buffers_with_timestamp()?

> +	}
> +
> +	iio_trigger_notify_done(indio_dev->trig);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int adc1x8s102_scan_direct(struct adc1x8s102_state *st, unsigned int ch)
> +{
> +	int ret;
> +
> +	st->tx_buf[0] = cpu_to_be16(ADC1x8S102_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 adc1x8s102_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val,
> +			   int *val2,
> +			   long m)
> +{
> +	int ret;
> +	struct adc1x8s102_state *st;
> +
> +	st = iio_priv(indio_dev);
> +
> +	switch (m) {
> +	case IIO_CHAN_INFO_RAW:

iio_device_claim_direct_mode()?

> +		mutex_lock(&indio_dev->mlock);
> +		if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
> +			ret = -EBUSY;
> +			dev_warn(&st->spi->dev,
> +			 "indio_dev->currentmode is INDIO_BUFFER_TRIGGERED\n");
> +		} else {
> +			ret = adc1x8s102_scan_direct(st, chan->address);
> +		}
> +		mutex_unlock(&indio_dev->mlock);
> +
> +		if (ret < 0)
> +			return ret;
> +		*val = ADC1x8S102_RES_DATA(ret);
> +
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_VOLTAGE:
> +			if (st->reg)
> +				*val = regulator_get_voltage(st->reg) / 1000;
> +			else
> +				*val = st->ext_vin;
> +
> +			*val2 = chan->scan_type.realbits;
> +			return IIO_VAL_FRACTIONAL_LOG2;
> +		default:
> +			dev_warn(&st->spi->dev,
> +				 "Invalid channel type %u for channel %d\n",
> +				 chan->type, chan->channel);

message necessary?

> +			return -EINVAL;
> +		}
> +	default:
> +		dev_warn(&st->spi->dev, "Invalid IIO_CHAN_INFO: %lu\n", m);

message necessary?

> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info adc1x8s102_info = {
> +	.read_raw		= &adc1x8s102_read_raw,
> +	.update_scan_mode	= &adc1x8s102_update_scan_mode,
> +	.driver_module		= THIS_MODULE,
> +};
> +
> +#ifdef CONFIG_ACPI
> +typedef int (*acpi_setup_handler)(struct spi_device *,
> +				  const struct adc1x8s102_platform_data **);
> +

no board specific stuff here please

> +static const struct adc1x8s102_platform_data int3495_platform_data = {
> +	.ext_vin = 5000,	/* 5 V */
> +};
> +
> +/* Galileo Gen 2 SPI setup */
> +static int
> +adc1x8s102_setup_int3495(struct spi_device *spi,
> +			 const struct adc1x8s102_platform_data **pdata)
> +{
> +	struct pxa2xx_spi_chip *chip_data;
> +
> +	chip_data = devm_kzalloc(&spi->dev, sizeof(*chip_data), GFP_KERNEL);
> +	if (!chip_data)
> +		return -ENOMEM;
> +
> +	chip_data->gpio_cs = ADC1x8S102_GALILEO2_CS;
> +	spi->controller_data = chip_data;
> +	dev_info(&spi->dev, "setting GPIO CS value to %d\n",
> +		 chip_data->gpio_cs);
> +	spi_setup(spi);
> +
> +	*pdata = &int3495_platform_data;
> +
> +	return 0;
> +}
> +
> +static const struct acpi_device_id adc1x8s102_acpi_ids[] = {
> +	{ "INT3495",  (kernel_ulong_t)&adc1x8s102_setup_int3495 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(acpi, adc1x8s102_acpi_ids);
> +#endif
> +
> +static int adc1x8s102_probe(struct spi_device *spi)
> +{
> +	const struct adc1x8s102_platform_data *pdata = spi->dev.platform_data;
> +	struct adc1x8s102_state *st;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +#ifdef CONFIG_ACPI
> +	if (ACPI_COMPANION(&spi->dev)) {
> +		acpi_setup_handler setup_handler;
> +		const struct acpi_device_id *id;
> +
> +		id = acpi_match_device(adc1x8s102_acpi_ids, &spi->dev);
> +		if (!id)
> +			return -ENODEV;
> +
> +		setup_handler = (acpi_setup_handler)id->driver_data;
> +		if (setup_handler) {
> +			ret = setup_handler(spi, &pdata);
> +			if (ret)
> +				return ret;
> +		}
> +	}
> +#endif
> +
> +	if (!pdata) {
> +		dev_err(&spi->dev, "Cannot get adc1x8s102 platform data\n");
> +		return -ENODEV;
> +	}
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +	st->ext_vin = pdata->ext_vin;
> +
> +	/* Use regulator, if available. */
> +	st->reg = devm_regulator_get(&spi->dev, "vref");
> +	if (IS_ERR(st->reg)) {
> +		dev_err(&spi->dev, "Cannot get 'vref' regulator\n");
> +		return PTR_ERR(st->reg);
> +	}
> +	ret = regulator_enable(st->reg);
> +	if (ret < 0) {
> +		dev_err(&spi->dev, "Cannot enable vref regulator\n");
> +		return ret;
> +	}
> +
> +	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 = adc1x8s102_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(adc1x8s102_channels);
> +	indio_dev->info = &adc1x8s102_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(__be16);
> +	st->scan_single_xfer.cs_change = 0;
> +
> +	spi_message_init(&st->scan_single_msg);
> +	spi_message_add_tail(&st->scan_single_xfer, &st->scan_single_msg);
> +
> +	ret = iio_triggered_buffer_setup(indio_dev, NULL,
> +			&adc1x8s102_trigger_handler, NULL);
> +	if (ret)
> +		goto error_disable_reg;
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret) {
> +		dev_err(&spi->dev,
> +			"Failed to register IIO device\n");
> +		goto error_cleanup_ring;
> +	}
> +	return 0;
> +
> +error_cleanup_ring:
> +	iio_triggered_buffer_cleanup(indio_dev);
> +error_disable_reg:
> +	regulator_disable(st->reg);
> +
> +	return ret;
> +}
> +
> +static int adc1x8s102_remove(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +	struct adc1x8s102_state *st = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +	iio_triggered_buffer_cleanup(indio_dev);
> +
> +	regulator_disable(st->reg);
> +
> +	return 0;
> +}
> +
> +static const struct spi_device_id adc1x8s102_id[] = {
> +	{ "adc1x8s102", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(spi, adc1x8s102_id);
> +
> +static struct spi_driver adc1x8s102_driver = {
> +	.driver = {
> +		.name   = "adc1x8s102",
> +		.owner	= THIS_MODULE,
> +		.acpi_match_table = ACPI_PTR(adc1x8s102_acpi_ids),
> +	},
> +	.probe		= adc1x8s102_probe,
> +	.remove		= adc1x8s102_remove,
> +	.id_table	= adc1x8s102_id,
> +};
> +module_spi_driver(adc1x8s102_driver);
> +
> +MODULE_AUTHOR("Bogdan Pricop <bogdan.pricop@...tex.com>");
> +MODULE_DESCRIPTION("Texas Instruments ADC1x8S102 driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/platform_data/adc1x8s102.h b/include/linux/platform_data/adc1x8s102.h
> new file mode 100644
> index 000000000000..6ad753c99823
> --- /dev/null
> +++ b/include/linux/platform_data/adc1x8s102.h
> @@ -0,0 +1,28 @@
> +/*
> + * ADC1x8S102 SPI ADC driver
> + *
> + * Copyright(c) 2013 Intel Corporation.
> + *
> + * 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.
> + */
> +
> +#ifndef __LINUX_PLATFORM_DATA_ADC1x8S102_H__
> +#define __LINUX_PLATFORM_DATA_ADC1x8S102_H__
> +
> +/**
> + * struct adc1x8s102_platform_data - Platform data for the adc1x8s102 ADC driver
> + * @ext_vin: External input voltage range for all voltage input channels
> + *	This is the voltage level of pin VA in millivolts
> + **/
> +struct adc1x8s102_platform_data {
> +	u16  ext_vin;
> +};
> +
> +#endif /* __LINUX_PLATFORM_DATA_ADC1x8S102_H__ */
> 

-- 

Peter Meerwald-Stadler
Mobile: +43 664 24 44 418

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