ad7766.c

/*
 * AD7766/AD7767 SPI ADC driver
 *
 * Copyright 2016 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>

#include <linux/iio/iio.h>
#include <linux/iio/buffer.h>
#include <linux/iio/trigger.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>

struct ad7766_chip_info {
	unsigned int decimation_factor;
};

enum {
	AD7766_SUPPLY_AVDD = 0,
	AD7766_SUPPLY_DVDD = 1,
	AD7766_SUPPLY_VREF = 2,
	AD7766_NUM_SUPPLIES = 3
};

struct ad7766 {
	const struct ad7766_chip_info *chip_info;
	struct spi_device *spi;
	struct clk *mclk;
	struct gpio_desc *pd_gpio;
	struct regulator_bulk_data reg[AD7766_NUM_SUPPLIES];

	struct iio_trigger *trig;

	struct spi_transfer xfer;
	struct spi_message msg;

	/*
	 * DMA (thus cache coherency maintenance) requires the
	 * transfer buffers to live in their own cache lines.
	 * Make the buffer large enough for one 24 bit sample and one 64 bit
	 * aligned 64 bit timestamp.
	 */
	unsigned char data[ALIGN(3, sizeof(s64)) + sizeof(s64)]
			____cacheline_aligned;
};

/*
 * AD7766 and AD7767 variations are interface compatible, the main difference is
 * analog performance. Both parts will use the same ID.
 */
enum ad7766_device_ids {
	ID_AD7766,
	ID_AD7766_1,
	ID_AD7766_2,
};

static irqreturn_t ad7766_trigger_handler(int irq, void *p)
{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct ad7766 *ad7766 = iio_priv(indio_dev);
	int ret;

	ret = spi_sync(ad7766->spi, &ad7766->msg);
	if (ret < 0)
		goto done;

	iio_push_to_buffers_with_timestamp(indio_dev, ad7766->data,
		pf->timestamp);
done:
	iio_trigger_notify_done(indio_dev->trig);

	return IRQ_HANDLED;
}

static int ad7766_preenable(struct iio_dev *indio_dev)
{
	struct ad7766 *ad7766 = iio_priv(indio_dev);
	int ret;

	ret = regulator_bulk_enable(ARRAY_SIZE(ad7766->reg), ad7766->reg);
	if (ret < 0) {
		dev_err(&ad7766->spi->dev, "Failed to enable supplies: %d\n",
			ret);
		return ret;
	}

	ret = clk_prepare_enable(ad7766->mclk);
	if (ret < 0) {
		dev_err(&ad7766->spi->dev, "Failed to enable MCLK: %d\n", ret);
		regulator_bulk_disable(ARRAY_SIZE(ad7766->reg), ad7766->reg);
		return ret;
	}

	gpiod_set_value(ad7766->pd_gpio, 0);

	return 0;
}

static int ad7766_postdisable(struct iio_dev *indio_dev)
{
	struct ad7766 *ad7766 = iio_priv(indio_dev);

	gpiod_set_value(ad7766->pd_gpio, 1);

	/*
	 * The PD pin is synchronous to the clock, so give it some time to
	 * notice the change before we disable the clock.
	 */
	msleep(20);

	clk_disable_unprepare(ad7766->mclk);
	regulator_bulk_disable(ARRAY_SIZE(ad7766->reg), ad7766->reg);

	return 0;
}

static int ad7766_read_raw(struct iio_dev *indio_dev,
	const struct iio_chan_spec *chan, int *val, int *val2, long info)
{
	struct ad7766 *ad7766 = iio_priv(indio_dev);
	struct regulator *vref = ad7766->reg[AD7766_SUPPLY_VREF].consumer;
	int scale_uv;

	switch (info) {
	case IIO_CHAN_INFO_SCALE:
		scale_uv = regulator_get_voltage(vref);
		if (scale_uv < 0)
			return scale_uv;
		*val = scale_uv / 1000;
		*val2 = chan->scan_type.realbits;
		return IIO_VAL_FRACTIONAL_LOG2;
	case IIO_CHAN_INFO_SAMP_FREQ:
		*val = clk_get_rate(ad7766->mclk) /
			ad7766->chip_info->decimation_factor;
		return IIO_VAL_INT;
	}
	return -EINVAL;
}

static const struct iio_chan_spec ad7766_channels[] = {
	{
		.type = IIO_VOLTAGE,
		.indexed = 1,
		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
		.scan_type = {
			.sign = 's',
			.realbits = 24,
			.storagebits = 32,
			.endianness = IIO_BE,
		},
	},
	IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct ad7766_chip_info ad7766_chip_info[] = {
	[ID_AD7766] = {
		.decimation_factor = 8,
	},
	[ID_AD7766_1] = {
		.decimation_factor = 16,
	},
	[ID_AD7766_2] = {
		.decimation_factor = 32,
	},
};

static const struct iio_buffer_setup_ops ad7766_buffer_setup_ops = {
	.preenable = &ad7766_preenable,
	.postenable = &iio_triggered_buffer_postenable,
	.predisable = &iio_triggered_buffer_predisable,
	.postdisable = &ad7766_postdisable,
};

static const struct iio_info ad7766_info = {
	.read_raw = &ad7766_read_raw,
};

static irqreturn_t ad7766_irq(int irq, void *private)
{
	iio_trigger_poll(private);
	return IRQ_HANDLED;
}

static int ad7766_set_trigger_state(struct iio_trigger *trig, bool enable)
{
	struct ad7766 *ad7766 = iio_trigger_get_drvdata(trig);

	if (enable)
		enable_irq(ad7766->spi->irq);
	else
		disable_irq(ad7766->spi->irq);

	return 0;
}

static const struct iio_trigger_ops ad7766_trigger_ops = {
	.set_trigger_state = ad7766_set_trigger_state,
	.validate_device = iio_trigger_validate_own_device,
};

static int ad7766_probe(struct spi_device *spi)
{
	const struct spi_device_id *id = spi_get_device_id(spi);
	struct iio_dev *indio_dev;
	struct ad7766 *ad7766;
	int ret;

	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*ad7766));
	if (!indio_dev)
		return -ENOMEM;

	ad7766 = iio_priv(indio_dev);
	ad7766->chip_info = &ad7766_chip_info[id->driver_data];

	ad7766->mclk = devm_clk_get(&spi->dev, "mclk");
	if (IS_ERR(ad7766->mclk))
		return PTR_ERR(ad7766->mclk);

	ad7766->reg[AD7766_SUPPLY_AVDD].supply = "avdd";
	ad7766->reg[AD7766_SUPPLY_DVDD].supply = "dvdd";
	ad7766->reg[AD7766_SUPPLY_VREF].supply = "vref";

	ret = devm_regulator_bulk_get(&spi->dev, ARRAY_SIZE(ad7766->reg),
		ad7766->reg);
	if (ret)
		return ret;

	ad7766->pd_gpio = devm_gpiod_get_optional(&spi->dev, "powerdown",
		GPIOD_OUT_HIGH);
	if (IS_ERR(ad7766->pd_gpio))
		return PTR_ERR(ad7766->pd_gpio);

	indio_dev->dev.parent = &spi->dev;
	indio_dev->name = spi_get_device_id(spi)->name;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = ad7766_channels;
	indio_dev->num_channels = ARRAY_SIZE(ad7766_channels);
	indio_dev->info = &ad7766_info;

	if (spi->irq > 0) {
		ad7766->trig = devm_iio_trigger_alloc(&spi->dev, "%s-dev%d",
			indio_dev->name, indio_dev->id);
		if (!ad7766->trig)
			return -ENOMEM;

		ad7766->trig->ops = &ad7766_trigger_ops;
		ad7766->trig->dev.parent = &spi->dev;
		iio_trigger_set_drvdata(ad7766->trig, ad7766);

		ret = devm_request_irq(&spi->dev, spi->irq, ad7766_irq,
			IRQF_TRIGGER_FALLING, dev_name(&spi->dev),
			ad7766->trig);
		if (ret < 0)
			return ret;

		/*
		 * The device generates interrupts as long as it is powered up.
		 * Some platforms might not allow the option to power it down so
		 * disable the interrupt to avoid extra load on the system
		 */
		disable_irq(spi->irq);

		ret = devm_iio_trigger_register(&spi->dev, ad7766->trig);
		if (ret)
			return ret;
	}

	spi_set_drvdata(spi, indio_dev);

	ad7766->spi = spi;

	/* First byte always 0 */
	ad7766->xfer.rx_buf = &ad7766->data[1];
	ad7766->xfer.len = 3;

	spi_message_init(&ad7766->msg);
	spi_message_add_tail(&ad7766->xfer, &ad7766->msg);

	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
		&iio_pollfunc_store_time, &ad7766_trigger_handler,
		&ad7766_buffer_setup_ops);
	if (ret)
		return ret;

	ret = devm_iio_device_register(&spi->dev, indio_dev);
	if (ret)
		return ret;
	return 0;
}

static const struct spi_device_id ad7766_id[] = {
	{"ad7766", ID_AD7766},
	{"ad7766-1", ID_AD7766_1},
	{"ad7766-2", ID_AD7766_2},
	{"ad7767", ID_AD7766},
	{"ad7767-1", ID_AD7766_1},
	{"ad7767-2", ID_AD7766_2},
	{}
};
MODULE_DEVICE_TABLE(spi, ad7766_id);

static struct spi_driver ad7766_driver = {
	.driver = {
		.name	= "ad7766",
	},
	.probe		= ad7766_probe,
	.id_table	= ad7766_id,
};
module_spi_driver(ad7766_driver);

MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
MODULE_DESCRIPTION("Analog Devices AD7766 and AD7767 ADCs driver support");
MODULE_LICENSE("GPL v2");