Message-ID: <56A4F806.7040604@kernel.org>
Date:	Sun, 24 Jan 2016 16:12:54 +0000
From:	Jonathan Cameron <jic23@...nel.org>
To:	Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Michael Hennerich <Michael.Hennerich@...log.com>,
	Hartmut Knaack <knaack.h@....de>,
	Peter Meerwald <pmeerw@...erw.net>, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8] iio: add ad5761 DAC driver

On 16/01/16 13:24, Ricardo Ribalda Delgado wrote:
> ad5761 is a 1-channel DAC with configurable output range.
> The driver uses the regulator interface for its voltage ref.
> 
> It shares its register layout with ad5761r, ad5721 and ad5721r.
> 
> Differences:
> ad5761* are 16 bit, ad5721* are 12 bits.
> ad57*1r have an internal reference.
> 
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>
Looks good to me.  One little nitpick inline that I'll clean up whilst
applying (right at the end!)

Applied to the togreg branch of iio.git. Initially pushed out as
testing for the autobuilders to play with it.

Thanks,

Jonathan

> ---
> v8: Move headers to include/linux/platform_data/
> 	Thanks to Lars-Peter Clausen <lars@...afoo.de>
> 
> v7: Remove check for !regulator
> 	Thanks to Jonathan Cameron <jic23@...nel.org>
> 
> v6: Do not set val2 when IIO_VAL_INT
> 	Document AD5761_VOLTAGE_RANGE_0V_5V
> 	Thanks to Jonathan Cameron <jic23@...nel.org>
> 
> v5: CodeStyle and check val2 value
>         Thanks to Peter Meerwald-Stadler <pmeerw@...erw.net> and
> 
> v4: Use locking mechanism
> 	Populate errors
> 	Thanks to Lars-Peter Clausen <lars@...afoo.de>
> 
> v3: Move programmable voltage range to pdata
> 	Exit on error instead of using internal voltage reference
>         Thanks to Jonathan Cameron <jic23@...nel.org>
> 
> v2: A lot of CodeStyle Fixes
>         Thanks to Peter Meerwald-Stadler <pmeerw@...erw.net> and
>         Jonathan Cameron <jic23@...nel.org>
> 
>  CREDITS                              |   1 +
>  drivers/iio/dac/Kconfig              |  10 +
>  drivers/iio/dac/Makefile             |   1 +
>  drivers/iio/dac/ad5761.c             | 430 +++++++++++++++++++++++++++++++++++
>  include/linux/platform_data/ad5761.h |  45 ++++
>  5 files changed, 487 insertions(+)
>  create mode 100644 drivers/iio/dac/ad5761.c
>  create mode 100644 include/linux/platform_data/ad5761.h
> 
> diff --git a/CREDITS b/CREDITS
> index 8207cc62ee9d..44ea433d70a1 100644
> --- a/CREDITS
> +++ b/CREDITS
> @@ -3035,6 +3035,7 @@ D: PLX USB338x driver
>  D: PCA9634 driver
>  D: Option GTM671WFS
>  D: Fintek F81216A
> +D: AD5761 iio driver
>  D: Various kernel hacks
>  S: Qtechnology A/S
>  S: Valby Langgade 142
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index e701e28fb1cd..4caedd671360 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -111,6 +111,16 @@ config AD5755
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called ad5755.
>  
> +config AD5761
> +	tristate "Analog Devices AD5761/61R/21/21R DAC driver"
> +	depends on SPI_MASTER
> +	help
> +	  Say yes here to build support for Analog Devices AD5761, AD5761R, AD5721,
> +	  AD5721R Digital to Analog Converter.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ad5761.
> +
>  config AD5764
>  	tristate "Analog Devices AD5764/64R/44/44R DAC driver"
>  	depends on SPI_MASTER
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 63ae05633e0c..cb525b53fc7b 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_AD5504) += ad5504.o
>  obj-$(CONFIG_AD5446) += ad5446.o
>  obj-$(CONFIG_AD5449) += ad5449.o
>  obj-$(CONFIG_AD5755) += ad5755.o
> +obj-$(CONFIG_AD5761) += ad5761.o
>  obj-$(CONFIG_AD5764) += ad5764.o
>  obj-$(CONFIG_AD5791) += ad5791.o
>  obj-$(CONFIG_AD5686) += ad5686.o
> diff --git a/drivers/iio/dac/ad5761.c b/drivers/iio/dac/ad5761.c
> new file mode 100644
> index 000000000000..d6510d6928b3
> --- /dev/null
> +++ b/drivers/iio/dac/ad5761.c
> @@ -0,0 +1,430 @@
> +/*
> + * AD5721, AD5721R, AD5761, AD5761R, Voltage Output Digital to Analog Converter
> + *
> + * Copyright 2016 Qtechnology A/S
> + * 2016 Ricardo Ribalda <ricardo.ribalda@...il.com>
> + *
> + * Licensed under the GPL-2.
> + */
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/spi/spi.h>
> +#include <linux/bitops.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/platform_data/ad5761.h>
> +
> +#define AD5761_ADDR(addr)		((addr & 0xf) << 16)
> +#define AD5761_ADDR_NOOP		0x0
> +#define AD5761_ADDR_DAC_WRITE		0x3
> +#define AD5761_ADDR_CTRL_WRITE_REG	0x4
> +#define AD5761_ADDR_SW_DATA_RESET	0x7
> +#define AD5761_ADDR_DAC_READ		0xb
> +#define AD5761_ADDR_CTRL_READ_REG	0xc
> +#define AD5761_ADDR_SW_FULL_RESET	0xf
> +
> +#define AD5761_CTRL_USE_INTVREF		BIT(5)
> +#define AD5761_CTRL_ETS			BIT(6)
> +
> +/**
> + * struct ad5761_chip_info - chip specific information
> + * @int_vref:	Value of the internal reference voltage in mV - 0 if external
> + *		reference voltage is used
> + * @channel:	channel specification
> +*/
> +
> +struct ad5761_chip_info {
> +	unsigned long int_vref;
> +	const struct iio_chan_spec channel;
> +};
> +
> +struct ad5761_range_params {
> +	int m;
> +	int c;
> +};
> +
> +enum ad5761_supported_device_ids {
> +	ID_AD5721,
> +	ID_AD5721R,
> +	ID_AD5761,
> +	ID_AD5761R,
> +};
> +
> +/**
> + * struct ad5761_state - driver instance specific data
> + * @spi:		spi_device
> + * @vref_reg:		reference voltage regulator
> + * @use_intref:		true when the internal voltage reference is used
> + * @vref:		actual voltage reference in mVolts
> + * @range:		output range mode used
> + * @data:		cache aligned spi buffer
> + */
> +struct ad5761_state {
> +	struct spi_device		*spi;
> +	struct regulator		*vref_reg;
> +
> +	bool use_intref;
> +	int vref;
> +	enum ad5761_voltage_range range;
> +
> +	/*
> +	 * DMA (thus cache coherency maintenance) requires the
> +	 * transfer buffers to live in their own cache lines.
> +	 */
> +	union {
> +		__be32 d32;
> +		u8 d8[4];
> +	} data[3] ____cacheline_aligned;
> +};
> +
> +static const struct ad5761_range_params ad5761_range_params[] = {
> +	[AD5761_VOLTAGE_RANGE_M10V_10V] = {
> +		.m = 80,
> +		.c = 40,
> +	},
> +	[AD5761_VOLTAGE_RANGE_0V_10V] = {
> +		.m = 40,
> +		.c = 0,
> +	},
> +	[AD5761_VOLTAGE_RANGE_M5V_5V] = {
> +		.m = 40,
> +		.c = 20,
> +	},
> +	[AD5761_VOLTAGE_RANGE_0V_5V] = {
> +		.m = 20,
> +		.c = 0,
> +	},
> +	[AD5761_VOLTAGE_RANGE_M2V5_7V5] = {
> +		.m = 40,
> +		.c = 10,
> +	},
> +	[AD5761_VOLTAGE_RANGE_M3V_3V] = {
> +		.m = 24,
> +		.c = 12,
> +	},
> +	[AD5761_VOLTAGE_RANGE_0V_16V] = {
> +		.m = 64,
> +		.c = 0,
> +	},
> +	[AD5761_VOLTAGE_RANGE_0V_20V] = {
> +		.m = 80,
> +		.c = 0,
> +	},
> +};
> +
> +static int _ad5761_spi_write(struct ad5761_state *st, u8 addr, u16 val)
> +{
> +	st->data[0].d32 = cpu_to_be32(AD5761_ADDR(addr) | val);
> +
> +	return spi_write(st->spi, &st->data[0].d8[1], 3);
> +}
> +
> +static int ad5761_spi_write(struct iio_dev *indio_dev, u8 addr, u16 val)
> +{
> +	struct ad5761_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	mutex_lock(&indio_dev->mlock);
> +	ret = _ad5761_spi_write(st, addr, val);
> +	mutex_unlock(&indio_dev->mlock);
> +
> +	return ret;
> +}
> +
> +static int _ad5761_spi_read(struct ad5761_state *st, u8 addr, u16 *val)
> +{
> +	int ret;
> +	struct spi_transfer xfers[] = {
> +		{
> +			.tx_buf = &st->data[0].d8[1],
> +			.bits_per_word = 8,
> +			.len = 3,
> +			.cs_change = true,
> +		}, {
> +			.tx_buf = &st->data[1].d8[1],
> +			.rx_buf = &st->data[2].d8[1],
> +			.bits_per_word = 8,
> +			.len = 3,
> +		},
> +	};
> +
> +	st->data[0].d32 = cpu_to_be32(AD5761_ADDR(addr));
> +	st->data[1].d32 = cpu_to_be32(AD5761_ADDR(AD5761_ADDR_NOOP));
> +
> +	ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
> +
> +	*val = be32_to_cpu(st->data[2].d32);
> +
> +	return ret;
> +}
> +
> +static int ad5761_spi_read(struct iio_dev *indio_dev, u8 addr, u16 *val)
> +{
> +	struct ad5761_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	mutex_lock(&indio_dev->mlock);
> +	ret = _ad5761_spi_read(st, addr, val);
> +	mutex_unlock(&indio_dev->mlock);
> +
> +	return ret;
> +}
> +
> +static int ad5761_spi_set_range(struct ad5761_state *st,
> +				enum ad5761_voltage_range range)
> +{
> +	u16 aux;
> +	int ret;
> +
> +	aux = (range & 0x7) | AD5761_CTRL_ETS;
> +
> +	if (st->use_intref)
> +		aux |= AD5761_CTRL_USE_INTVREF;
> +
> +	ret = _ad5761_spi_write(st, AD5761_ADDR_SW_FULL_RESET, 0);
> +	if (ret)
> +		return ret;
> +
> +	ret = _ad5761_spi_write(st, AD5761_ADDR_CTRL_WRITE_REG, aux);
> +	if (ret)
> +		return ret;
> +
> +	st->range = range;
> +
> +	return 0;
> +}
> +
> +static int ad5761_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val,
> +			   int *val2,
> +			   long mask)
> +{
> +	struct ad5761_state *st;
> +	int ret;
> +	u16 aux;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = ad5761_spi_read(indio_dev, AD5761_ADDR_DAC_READ, &aux);
> +		if (ret)
> +			return ret;
> +		*val = aux >> chan->scan_type.shift;
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		st = iio_priv(indio_dev);
> +		*val = st->vref * ad5761_range_params[st->range].m;
> +		*val /= 10;
> +		*val2 = chan->scan_type.realbits;
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	case IIO_CHAN_INFO_OFFSET:
> +		st = iio_priv(indio_dev);
> +		*val = -(1 << chan->scan_type.realbits);
> +		*val *=	ad5761_range_params[st->range].c;
> +		*val /=	ad5761_range_params[st->range].m;
> +		return IIO_VAL_INT;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ad5761_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int val,
> +			    int val2,
> +			    long mask)
> +{
> +	u16 aux;
> +
> +	if (mask != IIO_CHAN_INFO_RAW)
> +		return -EINVAL;
> +
> +	if (val2 || (val << chan->scan_type.shift) > 0xffff || val < 0)
> +		return -EINVAL;
> +
> +	aux = val << chan->scan_type.shift;
> +
> +	return ad5761_spi_write(indio_dev, AD5761_ADDR_DAC_WRITE, aux);
> +}
> +
> +static const struct iio_info ad5761_info = {
> +	.read_raw = &ad5761_read_raw,
> +	.write_raw = &ad5761_write_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +#define AD5761_CHAN(_bits) {				\
> +	.type = IIO_VOLTAGE,				\
> +	.output = 1,					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |	\
> +		BIT(IIO_CHAN_INFO_OFFSET),		\
> +	.scan_type = {					\
> +		.sign = 'u',				\
> +		.realbits = (_bits),			\
> +		.storagebits = 16,			\
> +		.shift = 16 - (_bits),			\
> +	},						\
> +}
> +
> +static const struct ad5761_chip_info ad5761_chip_infos[] = {
> +	[ID_AD5721] = {
> +		.int_vref = 0,
> +		.channel = AD5761_CHAN(12),
> +	},
> +	[ID_AD5721R] = {
> +		.int_vref = 2500,
> +		.channel = AD5761_CHAN(12),
> +	},
> +	[ID_AD5761] = {
> +		.int_vref = 0,
> +		.channel = AD5761_CHAN(16),
> +	},
> +	[ID_AD5761R] = {
> +		.int_vref = 2500,
> +		.channel = AD5761_CHAN(16),
> +	},
> +};
> +
> +static int ad5761_get_vref(struct ad5761_state *st,
> +			   const struct ad5761_chip_info *chip_info)
> +{
> +	int ret;
> +
> +	st->vref_reg = devm_regulator_get_optional(&st->spi->dev, "vref");
> +	if (PTR_ERR(st->vref_reg) == -ENODEV) {
> +		/* Use Internal regulator */
> +		if (!chip_info->int_vref) {
> +			dev_err(&st->spi->dev,
> +				"Voltage reference not found\n");
> +			return -EIO;
> +		}
> +
> +		st->use_intref = true;
> +		st->vref = chip_info->int_vref;
> +		return 0;
> +	}
> +
> +	if (IS_ERR(st->vref_reg)) {
> +		dev_err(&st->spi->dev,
> +			"Error getting voltage reference regulator\n");
> +		return PTR_ERR(st->vref_reg);
> +	}
> +
> +	ret = regulator_enable(st->vref_reg);
> +	if (ret) {
> +		dev_err(&st->spi->dev,
> +			 "Failed to enable voltage reference\n");
> +		return ret;
> +	}
> +
> +	ret = regulator_get_voltage(st->vref_reg);
> +	if (ret < 0) {
> +		dev_err(&st->spi->dev,
> +			 "Failed to get voltage reference value\n");
> +		goto disable_regulator_vref;
> +	}
> +
> +	if (ret < 2000000 || ret > 3000000) {
> +		dev_warn(&st->spi->dev,
> +			 "Invalid external voltage ref. value %d uV\n", ret);
> +		ret = -EIO;
> +		goto disable_regulator_vref;
> +	}
> +
> +	st->vref = ret / 1000;
> +	st->use_intref = false;
> +
> +	return 0;
> +
> +disable_regulator_vref:
> +	regulator_disable(st->vref_reg);
> +	st->vref_reg = NULL;
> +	return ret;
> +}
> +
> +static int ad5761_probe(struct spi_device *spi)
> +{
> +	struct iio_dev *iio_dev;
> +	struct ad5761_state *st;
> +	int ret;
> +	const struct ad5761_chip_info *chip_info =
> +		&ad5761_chip_infos[spi_get_device_id(spi)->driver_data];
> +	enum ad5761_voltage_range voltage_range = AD5761_VOLTAGE_RANGE_0V_5V;
> +	struct ad5761_platform_data *pdata = dev_get_platdata(&spi->dev);
> +
> +	iio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> +	if (!iio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(iio_dev);
> +
> +	st->spi = spi;
> +	spi_set_drvdata(spi, iio_dev);
> +
> +	ret = ad5761_get_vref(st, chip_info);
> +	if (ret)
> +		return ret;
> +
> +	if (pdata)
> +		voltage_range = pdata->voltage_range;
> +
> +	ret = ad5761_spi_set_range(st, voltage_range);
> +	if (ret)
> +		goto disable_regulator_err;
> +
> +	iio_dev->dev.parent = &spi->dev;
> +	iio_dev->info = &ad5761_info;
> +	iio_dev->modes = INDIO_DIRECT_MODE;
> +	iio_dev->channels = &chip_info->channel;
> +	iio_dev->num_channels = 1;
> +	iio_dev->name = spi_get_device_id(st->spi)->name;
> +	ret = iio_device_register(iio_dev);
> +	if (ret)
> +		goto disable_regulator_err;
> +
> +	return 0;
> +
> +disable_regulator_err:
> +	if (!IS_ERR_OR_NULL(st->vref_reg))
> +		regulator_disable(st->vref_reg);
> +
> +	return ret;
> +}
> +
> +static int ad5761_remove(struct spi_device *spi)
> +{
> +	struct iio_dev *iio_dev = spi_get_drvdata(spi);
> +	struct ad5761_state *st = iio_priv(iio_dev);
> +
> +	iio_device_unregister(iio_dev);
> +
> +	if (!IS_ERR_OR_NULL(st->vref_reg))
> +		regulator_disable(st->vref_reg);
> +
> +	return 0;
> +}
> +
> +static const struct spi_device_id ad5761_id[] = {
> +	{"ad5721", ID_AD5721},
> +	{"ad5721r", ID_AD5721R},
> +	{"ad5761", ID_AD5761},
> +	{"ad5761r", ID_AD5761R},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(spi, ad5761_id);
> +
> +static struct spi_driver ad5761_driver = {
> +	.driver = {
> +		   .name = "ad5761",
> +		   },
> +	.probe = ad5761_probe,
> +	.remove = ad5761_remove,
> +	.id_table = ad5761_id,
> +};
> +module_spi_driver(ad5761_driver);
> +
> +MODULE_AUTHOR("Ricardo Ribalda <ricardo.ribalda@...il.com>");
> +MODULE_DESCRIPTION("Analog Devices AD5721, AD5721R, AD5761, AD5761R driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/platform_data/ad5761.h b/include/linux/platform_data/ad5761.h
> new file mode 100644
> index 000000000000..1d67625ae2cd
> --- /dev/null
> +++ b/include/linux/platform_data/ad5761.h
> @@ -0,0 +1,45 @@
> +/*
> + * AD5721, AD5721R, AD5761, AD5761R, Voltage Output Digital to Analog Converter
> + *
> + * Copyright 2016 Qtechnology A/S
> + * 2016 Ricardo Ribalda <ricardo.ribalda@...il.com>
> + *
> + * Licensed under the GPL-2.
> + */
> +#ifndef __LINUX_PLATFORM_DATA_AD5761_H__
> +#define __LINUX_PLATFORM_DATA_AD5761_H__
> +
> +/**
> + * enum ad5761_voltage_range - Voltage range the AD5761 is configured for.
> + * @AD5761_VOLTAGE_RANGE_M10V_10V:  -10V to  10V
> + * @AD5761_VOLTAGE_RANGE_0V_10V:      0V to  10V
> + * @AD5761_VOLTAGE_RANGE_M5V_5V:     -5V to   5V
> + * @AD5761_VOLTAGE_RANGE_0V_5V:       0V to   5V
> + * @AD5761_VOLTAGE_RANGE_M2V5_7V5: -2.5V to 7.5V
> + * @AD5761_VOLTAGE_RANGE_M3V_3V:     -3V to   3V
> + * @AD5761_VOLTAGE_RANGE_0V_16V:      0V to  16V
> + * @AD5761_VOLTAGE_RANGE_0V_20V:      0V to  20V
> + */
> +
> +enum ad5761_voltage_range {
> +	AD5761_VOLTAGE_RANGE_M10V_10V,
> +	AD5761_VOLTAGE_RANGE_0V_10V,
> +	AD5761_VOLTAGE_RANGE_M5V_5V,
> +	AD5761_VOLTAGE_RANGE_0V_5V,
> +	AD5761_VOLTAGE_RANGE_M2V5_7V5,
> +	AD5761_VOLTAGE_RANGE_M3V_3V,
> +	AD5761_VOLTAGE_RANGE_0V_16V,
> +	AD5761_VOLTAGE_RANGE_0V_20V,
> +};
> +
> +/**
> + * struct ad5761_platform_data - AD5761 DAC driver platform data
> + * @voltage_range: Voltage range the AD5761 is configured for
> + */
> +
> +struct ad5761_platform_data {
> +	enum ad5761_voltage_range voltage_range;
> +};
Really trivial but one blank line is plenty here - I'll fix this up when
applying.
> +
> +
> +#endif
> 

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