drivers/iio/adc/ti-adc12138.c - third_party/linux - Git at Google

 /*
  * ADC12130/ADC12132/ADC12138 12-bit plus sign ADC driver
  *
  * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
  *
  * This file is subject to the terms and conditions of version 2 of
  * the GNU General Public License.  See the file COPYING in the main
  * directory of this archive for more details.
  *
  * Datasheet: http://www.ti.com/lit/ds/symlink/adc12138.pdf
  */

 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/completion.h>
 #include <linux/clk.h>
 #include <linux/spi/spi.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/buffer.h>
 #include <linux/iio/trigger.h>
 #include <linux/iio/triggered_buffer.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/regulator/consumer.h>

 #define ADC12138_MODE_AUTO_CAL			0x08
 #define ADC12138_MODE_READ_STATUS		0x0c
 #define ADC12138_MODE_ACQUISITION_TIME_6	0x0e
 #define ADC12138_MODE_ACQUISITION_TIME_10	0x4e
 #define ADC12138_MODE_ACQUISITION_TIME_18	0x8e
 #define ADC12138_MODE_ACQUISITION_TIME_34	0xce

 #define ADC12138_STATUS_CAL			BIT(6)

 enum {
 	adc12130,
 	adc12132,
 	adc12138,
 };

 struct adc12138 {
 	struct spi_device *spi;
 	unsigned int id;
 	/* conversion clock */
 	struct clk *cclk;
 	/* positive analog voltage reference */
 	struct regulator *vref_p;
 	/* negative analog voltage reference */
 	struct regulator *vref_n;
 	struct mutex lock;
 	struct completion complete;
 	/* The number of cclk periods for the S/H's acquisition time */
 	unsigned int acquisition_time;
 	/*
 	 * Maximum size needed: 16x 2 bytes ADC data + 8 bytes timestamp.
 	 * Less may be need if not all channels are enabled, as long as
 	 * the 8 byte alignment of the timestamp is maintained.
 	 */
 	__be16 data[20] __aligned(8);

 	u8 tx_buf[2] ____cacheline_aligned;
 	u8 rx_buf[2];
 };

 #define ADC12138_VOLTAGE_CHANNEL(chan)					\
 	{								\
 		.type = IIO_VOLTAGE,					\
 		.indexed = 1,						\
 		.channel = chan,					\
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)	\
 					| BIT(IIO_CHAN_INFO_OFFSET),	\
 		.scan_index = chan,					\
 		.scan_type = {						\
 			.sign = 's',					\
 			.realbits = 13,					\
 			.storagebits = 16,				\
 			.shift = 3,					\
 			.endianness = IIO_BE,				\
 		},							\
 	}

 #define ADC12138_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si)			\
 	{								\
 		.type = IIO_VOLTAGE,					\
 		.indexed = 1,						\
 		.channel = (chan1),					\
 		.channel2 = (chan2),					\
 		.differential = 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_index = si,					\
 		.scan_type = {						\
 			.sign = 's',					\
 			.realbits = 13,					\
 			.storagebits = 16,				\
 			.shift = 3,					\
 			.endianness = IIO_BE,				\
 		},							\
 	}

 static const struct iio_chan_spec adc12132_channels[] = {
 	ADC12138_VOLTAGE_CHANNEL(0),
 	ADC12138_VOLTAGE_CHANNEL(1),
 	ADC12138_VOLTAGE_CHANNEL_DIFF(0, 1, 2),
 	ADC12138_VOLTAGE_CHANNEL_DIFF(1, 0, 3),
 	IIO_CHAN_SOFT_TIMESTAMP(4),
 };

 static const struct iio_chan_spec adc12138_channels[] = {
 	ADC12138_VOLTAGE_CHANNEL(0),
 	ADC12138_VOLTAGE_CHANNEL(1),
 	ADC12138_VOLTAGE_CHANNEL(2),
 	ADC12138_VOLTAGE_CHANNEL(3),
 	ADC12138_VOLTAGE_CHANNEL(4),
 	ADC12138_VOLTAGE_CHANNEL(5),
 	ADC12138_VOLTAGE_CHANNEL(6),
 	ADC12138_VOLTAGE_CHANNEL(7),
 	ADC12138_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
 	ADC12138_VOLTAGE_CHANNEL_DIFF(1, 0, 9),
 	ADC12138_VOLTAGE_CHANNEL_DIFF(2, 3, 10),
 	ADC12138_VOLTAGE_CHANNEL_DIFF(3, 2, 11),
 	ADC12138_VOLTAGE_CHANNEL_DIFF(4, 5, 12),
 	ADC12138_VOLTAGE_CHANNEL_DIFF(5, 4, 13),
 	ADC12138_VOLTAGE_CHANNEL_DIFF(6, 7, 14),
 	ADC12138_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
 	IIO_CHAN_SOFT_TIMESTAMP(16),
 };

 static int adc12138_mode_programming(struct adc12138 *adc, u8 mode,
 				     void *rx_buf, int len)
 {
 	struct spi_transfer xfer = {
 		.tx_buf = adc->tx_buf,
 		.rx_buf = adc->rx_buf,
 		.len = len,
 	};
 	int ret;

 	/* Skip unused bits for ADC12130 and ADC12132 */
 	if (adc->id != adc12138)
 		mode = (mode & 0xc0) | ((mode & 0x0f) << 2);

 	adc->tx_buf[0] = mode;

 	ret = spi_sync_transfer(adc->spi, &xfer, 1);
 	if (ret)
 		return ret;

 	memcpy(rx_buf, adc->rx_buf, len);

 	return 0;
 }

 static int adc12138_read_status(struct adc12138 *adc)
 {
 	u8 rx_buf[2];
 	int ret;

 	ret = adc12138_mode_programming(adc, ADC12138_MODE_READ_STATUS,
 					rx_buf, 2);
 	if (ret)
 		return ret;

 	return (rx_buf[0] << 1) | (rx_buf[1] >> 7);
 }

 static int __adc12138_start_conv(struct adc12138 *adc,
 				 struct iio_chan_spec const *channel,
 				 void *data, int len)

 {
 	static const u8 ch_to_mux[] = { 0, 4, 1, 5, 2, 6, 3, 7 };
 	u8 mode = (ch_to_mux[channel->channel] << 4) |
 		  (channel->differential ? 0 : 0x80);

 	return adc12138_mode_programming(adc, mode, data, len);
 }

 static int adc12138_start_conv(struct adc12138 *adc,
 			       struct iio_chan_spec const *channel)
 {
 	u8 trash;

 	return __adc12138_start_conv(adc, channel, &trash, 1);
 }

 static int adc12138_start_and_read_conv(struct adc12138 *adc,
 					struct iio_chan_spec const *channel,
 					__be16 *data)
 {
 	return __adc12138_start_conv(adc, channel, data, 2);
 }

 static int adc12138_read_conv_data(struct adc12138 *adc, __be16 *value)
 {
 	/* Issue a read status instruction and read previous conversion data */
 	return adc12138_mode_programming(adc, ADC12138_MODE_READ_STATUS,
 					 value, sizeof(*value));
 }

 static int adc12138_wait_eoc(struct adc12138 *adc, unsigned long timeout)
 {
 	if (!wait_for_completion_timeout(&adc->complete, timeout))
 		return -ETIMEDOUT;

 	return 0;
 }

 static int adc12138_adc_conversion(struct adc12138 *adc,
 				   struct iio_chan_spec const *channel,
 				   __be16 *value)
 {
 	int ret;

 	reinit_completion(&adc->complete);

 	ret = adc12138_start_conv(adc, channel);
 	if (ret)
 		return ret;

 	ret = adc12138_wait_eoc(adc, msecs_to_jiffies(100));
 	if (ret)
 		return ret;

 	return adc12138_read_conv_data(adc, value);
 }

 static int adc12138_read_raw(struct iio_dev *iio,
 			     struct iio_chan_spec const *channel, int *value,
 			     int *shift, long mask)
 {
 	struct adc12138 *adc = iio_priv(iio);
 	int ret;
 	__be16 data;

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		mutex_lock(&adc->lock);
 		ret = adc12138_adc_conversion(adc, channel, &data);
 		mutex_unlock(&adc->lock);
 		if (ret)
 			return ret;

 		*value = sign_extend32(be16_to_cpu(data) >> 3, 12);

 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		ret = regulator_get_voltage(adc->vref_p);
 		if (ret < 0)
 			return ret;
 		*value = ret;

 		if (!IS_ERR(adc->vref_n)) {
 			ret = regulator_get_voltage(adc->vref_n);
 			if (ret < 0)
 				return ret;
 			*value -= ret;
 		}

 		/* convert regulator output voltage to mV */
 		*value /= 1000;
 		*shift = channel->scan_type.realbits - 1;

 		return IIO_VAL_FRACTIONAL_LOG2;
 	case IIO_CHAN_INFO_OFFSET:
 		if (!IS_ERR(adc->vref_n)) {
 			*value = regulator_get_voltage(adc->vref_n);
 			if (*value < 0)
 				return *value;
 		} else {
 			*value = 0;
 		}

 		/* convert regulator output voltage to mV */
 		*value /= 1000;

 		return IIO_VAL_INT;
 	}

 	return -EINVAL;
 }

 static const struct iio_info adc12138_info = {
 	.read_raw = adc12138_read_raw,
 };

 static int adc12138_init(struct adc12138 *adc)
 {
 	int ret;
 	int status;
 	u8 mode;
 	u8 trash;

 	reinit_completion(&adc->complete);

 	ret = adc12138_mode_programming(adc, ADC12138_MODE_AUTO_CAL, &trash, 1);
 	if (ret)
 		return ret;

 	/* data output at this time has no significance */
 	status = adc12138_read_status(adc);
 	if (status < 0)
 		return status;

 	adc12138_wait_eoc(adc, msecs_to_jiffies(100));

 	status = adc12138_read_status(adc);
 	if (status & ADC12138_STATUS_CAL) {
 		dev_warn(&adc->spi->dev,
 			"Auto Cal sequence is still in progress: %#x\n",
 			status);
 		return -EIO;
 	}

 	switch (adc->acquisition_time) {
 	case 6:
 		mode = ADC12138_MODE_ACQUISITION_TIME_6;
 		break;
 	case 10:
 		mode = ADC12138_MODE_ACQUISITION_TIME_10;
 		break;
 	case 18:
 		mode = ADC12138_MODE_ACQUISITION_TIME_18;
 		break;
 	case 34:
 		mode = ADC12138_MODE_ACQUISITION_TIME_34;
 		break;
 	default:
 		return -EINVAL;
 	}

 	return adc12138_mode_programming(adc, mode, &trash, 1);
 }

 static irqreturn_t adc12138_trigger_handler(int irq, void *p)
 {
 	struct iio_poll_func *pf = p;
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct adc12138 *adc = iio_priv(indio_dev);
 	__be16 trash;
 	int ret;
 	int scan_index;
 	int i = 0;

 	mutex_lock(&adc->lock);

 	for_each_set_bit(scan_index, indio_dev->active_scan_mask,
 			 indio_dev->masklength) {
 		const struct iio_chan_spec *scan_chan =
 				&indio_dev->channels[scan_index];

 		reinit_completion(&adc->complete);

 		ret = adc12138_start_and_read_conv(adc, scan_chan,
 					i ? &adc->data[i - 1] : &trash);
 		if (ret) {
 			dev_warn(&adc->spi->dev,
 				 "failed to start conversion\n");
 			goto out;
 		}

 		ret = adc12138_wait_eoc(adc, msecs_to_jiffies(100));
 		if (ret) {
 			dev_warn(&adc->spi->dev, "wait eoc timeout\n");
 			goto out;
 		}

 		i++;
 	}

 	if (i) {
 		ret = adc12138_read_conv_data(adc, &adc->data[i - 1]);
 		if (ret) {
 			dev_warn(&adc->spi->dev,
 				 "failed to get conversion data\n");
 			goto out;
 		}
 	}

 	iio_push_to_buffers_with_timestamp(indio_dev, adc->data,
 					   iio_get_time_ns(indio_dev));
 out:
 	mutex_unlock(&adc->lock);

 	iio_trigger_notify_done(indio_dev->trig);

 	return IRQ_HANDLED;
 }

 static irqreturn_t adc12138_eoc_handler(int irq, void *p)
 {
 	struct iio_dev *indio_dev = p;
 	struct adc12138 *adc = iio_priv(indio_dev);

 	complete(&adc->complete);

 	return IRQ_HANDLED;
 }

 static int adc12138_probe(struct spi_device *spi)
 {
 	struct iio_dev *indio_dev;
 	struct adc12138 *adc;
 	int ret;

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

 	adc = iio_priv(indio_dev);
 	adc->spi = spi;
 	adc->id = spi_get_device_id(spi)->driver_data;
 	mutex_init(&adc->lock);
 	init_completion(&adc->complete);

 	indio_dev->name = spi_get_device_id(spi)->name;
 	indio_dev->dev.parent = &spi->dev;
 	indio_dev->info = &adc12138_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;

 	switch (adc->id) {
 	case adc12130:
 	case adc12132:
 		indio_dev->channels = adc12132_channels;
 		indio_dev->num_channels = ARRAY_SIZE(adc12132_channels);
 		break;
 	case adc12138:
 		indio_dev->channels = adc12138_channels;
 		indio_dev->num_channels = ARRAY_SIZE(adc12138_channels);
 		break;
 	default:
 		return -EINVAL;
 	}

 	ret = of_property_read_u32(spi->dev.of_node, "ti,acquisition-time",
 				   &adc->acquisition_time);
 	if (ret)
 		adc->acquisition_time = 10;

 	adc->cclk = devm_clk_get(&spi->dev, NULL);
 	if (IS_ERR(adc->cclk))
 		return PTR_ERR(adc->cclk);

 	adc->vref_p = devm_regulator_get(&spi->dev, "vref-p");
 	if (IS_ERR(adc->vref_p))
 		return PTR_ERR(adc->vref_p);

 	adc->vref_n = devm_regulator_get_optional(&spi->dev, "vref-n");
 	if (IS_ERR(adc->vref_n)) {
 		/*
 		 * Assume vref_n is 0V if an optional regulator is not
 		 * specified, otherwise return the error code.
 		 */
 		ret = PTR_ERR(adc->vref_n);
 		if (ret != -ENODEV)
 			return ret;
 	}

 	ret = devm_request_irq(&spi->dev, spi->irq, adc12138_eoc_handler,
 			       IRQF_TRIGGER_RISING, indio_dev->name, indio_dev);
 	if (ret)
 		return ret;

 	ret = clk_prepare_enable(adc->cclk);
 	if (ret)
 		return ret;

 	ret = regulator_enable(adc->vref_p);
 	if (ret)
 		goto err_clk_disable;

 	if (!IS_ERR(adc->vref_n)) {
 		ret = regulator_enable(adc->vref_n);
 		if (ret)
 			goto err_vref_p_disable;
 	}

 	ret = adc12138_init(adc);
 	if (ret)
 		goto err_vref_n_disable;

 	spi_set_drvdata(spi, indio_dev);

 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
 					 adc12138_trigger_handler, NULL);
 	if (ret)
 		goto err_vref_n_disable;

 	ret = iio_device_register(indio_dev);
 	if (ret)
 		goto err_buffer_cleanup;

 	return 0;
 err_buffer_cleanup:
 	iio_triggered_buffer_cleanup(indio_dev);
 err_vref_n_disable:
 	if (!IS_ERR(adc->vref_n))
 		regulator_disable(adc->vref_n);
 err_vref_p_disable:
 	regulator_disable(adc->vref_p);
 err_clk_disable:
 	clk_disable_unprepare(adc->cclk);

 	return ret;
 }

 static int adc12138_remove(struct spi_device *spi)
 {
 	struct iio_dev *indio_dev = spi_get_drvdata(spi);
 	struct adc12138 *adc = iio_priv(indio_dev);

 	iio_device_unregister(indio_dev);
 	iio_triggered_buffer_cleanup(indio_dev);
 	if (!IS_ERR(adc->vref_n))
 		regulator_disable(adc->vref_n);
 	regulator_disable(adc->vref_p);
 	clk_disable_unprepare(adc->cclk);

 	return 0;
 }

 #ifdef CONFIG_OF

 static const struct of_device_id adc12138_dt_ids[] = {
 	{ .compatible = "ti,adc12130", },
 	{ .compatible = "ti,adc12132", },
 	{ .compatible = "ti,adc12138", },
 	{}
 };
 MODULE_DEVICE_TABLE(of, adc12138_dt_ids);

 #endif

 static const struct spi_device_id adc12138_id[] = {
 	{ "adc12130", adc12130 },
 	{ "adc12132", adc12132 },
 	{ "adc12138", adc12138 },
 	{}
 };
 MODULE_DEVICE_TABLE(spi, adc12138_id);

 static struct spi_driver adc12138_driver = {
 	.driver = {
 		.name = "adc12138",
 		.of_match_table = of_match_ptr(adc12138_dt_ids),
 	},
 	.probe = adc12138_probe,
 	.remove = adc12138_remove,
 	.id_table = adc12138_id,
 };
 module_spi_driver(adc12138_driver);

 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 MODULE_DESCRIPTION("ADC12130/ADC12132/ADC12138 driver");
 MODULE_LICENSE("GPL v2");
	/*
	* ADC12130/ADC12132/ADC12138 12-bit plus sign ADC driver
	*
	* Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
	*
	* This file is subject to the terms and conditions of version 2 of
	* the GNU General Public License. See the file COPYING in the main
	* directory of this archive for more details.
	*
	* Datasheet: http://www.ti.com/lit/ds/symlink/adc12138.pdf
	*/

	#include <linux/module.h>
	#include <linux/interrupt.h>
	#include <linux/completion.h>
	#include <linux/clk.h>
	#include <linux/spi/spi.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/buffer.h>
	#include <linux/iio/trigger.h>
	#include <linux/iio/triggered_buffer.h>
	#include <linux/iio/trigger_consumer.h>
	#include <linux/regulator/consumer.h>

	#define ADC12138_MODE_AUTO_CAL 0x08
	#define ADC12138_MODE_READ_STATUS 0x0c
	#define ADC12138_MODE_ACQUISITION_TIME_6 0x0e
	#define ADC12138_MODE_ACQUISITION_TIME_10 0x4e
	#define ADC12138_MODE_ACQUISITION_TIME_18 0x8e
	#define ADC12138_MODE_ACQUISITION_TIME_34 0xce

	#define ADC12138_STATUS_CAL BIT(6)

	enum {
	adc12130,
	adc12132,
	adc12138,
	};

	struct adc12138 {
	struct spi_device *spi;
	unsigned int id;
	/* conversion clock */
	struct clk *cclk;
	/* positive analog voltage reference */
	struct regulator *vref_p;
	/* negative analog voltage reference */
	struct regulator *vref_n;
	struct mutex lock;
	struct completion complete;
	/* The number of cclk periods for the S/H's acquisition time */
	unsigned int acquisition_time;
	/*
	* Maximum size needed: 16x 2 bytes ADC data + 8 bytes timestamp.
	* Less may be need if not all channels are enabled, as long as
	* the 8 byte alignment of the timestamp is maintained.
	*/
	__be16 data[20] __aligned(8);

	u8 tx_buf[2] ____cacheline_aligned;
	u8 rx_buf[2];
	};

	#define ADC12138_VOLTAGE_CHANNEL(chan) \
	{ \
	.type = IIO_VOLTAGE, \
	.indexed = 1, \
	.channel = chan, \
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
	\| BIT(IIO_CHAN_INFO_OFFSET), \
	.scan_index = chan, \
	.scan_type = { \
	.sign = 's', \
	.realbits = 13, \
	.storagebits = 16, \
	.shift = 3, \
	.endianness = IIO_BE, \
	}, \
	}

	#define ADC12138_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si) \
	{ \
	.type = IIO_VOLTAGE, \
	.indexed = 1, \
	.channel = (chan1), \
	.channel2 = (chan2), \
	.differential = 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_index = si, \
	.scan_type = { \
	.sign = 's', \
	.realbits = 13, \
	.storagebits = 16, \
	.shift = 3, \
	.endianness = IIO_BE, \
	}, \
	}

	static const struct iio_chan_spec adc12132_channels[] = {
	ADC12138_VOLTAGE_CHANNEL(0),
	ADC12138_VOLTAGE_CHANNEL(1),
	ADC12138_VOLTAGE_CHANNEL_DIFF(0, 1, 2),
	ADC12138_VOLTAGE_CHANNEL_DIFF(1, 0, 3),
	IIO_CHAN_SOFT_TIMESTAMP(4),
	};

	static const struct iio_chan_spec adc12138_channels[] = {
	ADC12138_VOLTAGE_CHANNEL(0),
	ADC12138_VOLTAGE_CHANNEL(1),
	ADC12138_VOLTAGE_CHANNEL(2),
	ADC12138_VOLTAGE_CHANNEL(3),
	ADC12138_VOLTAGE_CHANNEL(4),
	ADC12138_VOLTAGE_CHANNEL(5),
	ADC12138_VOLTAGE_CHANNEL(6),
	ADC12138_VOLTAGE_CHANNEL(7),
	ADC12138_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
	ADC12138_VOLTAGE_CHANNEL_DIFF(1, 0, 9),
	ADC12138_VOLTAGE_CHANNEL_DIFF(2, 3, 10),
	ADC12138_VOLTAGE_CHANNEL_DIFF(3, 2, 11),
	ADC12138_VOLTAGE_CHANNEL_DIFF(4, 5, 12),
	ADC12138_VOLTAGE_CHANNEL_DIFF(5, 4, 13),
	ADC12138_VOLTAGE_CHANNEL_DIFF(6, 7, 14),
	ADC12138_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
	IIO_CHAN_SOFT_TIMESTAMP(16),
	};

	static int adc12138_mode_programming(struct adc12138 *adc, u8 mode,
	void *rx_buf, int len)
	{
	struct spi_transfer xfer = {
	.tx_buf = adc->tx_buf,
	.rx_buf = adc->rx_buf,
	.len = len,
	};
	int ret;

	/* Skip unused bits for ADC12130 and ADC12132 */
	if (adc->id != adc12138)
	mode = (mode & 0xc0) \| ((mode & 0x0f) << 2);

	adc->tx_buf[0] = mode;

	ret = spi_sync_transfer(adc->spi, &xfer, 1);
	if (ret)
	return ret;

	memcpy(rx_buf, adc->rx_buf, len);

	return 0;
	}

	static int adc12138_read_status(struct adc12138 *adc)
	{
	u8 rx_buf[2];
	int ret;

	ret = adc12138_mode_programming(adc, ADC12138_MODE_READ_STATUS,
	rx_buf, 2);
	if (ret)
	return ret;

	return (rx_buf[0] << 1) \| (rx_buf[1] >> 7);
	}

	static int __adc12138_start_conv(struct adc12138 *adc,
	struct iio_chan_spec const *channel,
	void *data, int len)

	{
	static const u8 ch_to_mux[] = { 0, 4, 1, 5, 2, 6, 3, 7 };
	u8 mode = (ch_to_mux[channel->channel] << 4) \|
	(channel->differential ? 0 : 0x80);

	return adc12138_mode_programming(adc, mode, data, len);
	}

	static int adc12138_start_conv(struct adc12138 *adc,
	struct iio_chan_spec const *channel)
	{
	u8 trash;

	return __adc12138_start_conv(adc, channel, &trash, 1);
	}

	static int adc12138_start_and_read_conv(struct adc12138 *adc,
	struct iio_chan_spec const *channel,
	__be16 *data)
	{
	return __adc12138_start_conv(adc, channel, data, 2);
	}

	static int adc12138_read_conv_data(struct adc12138 adc, __be16 value)
	{
	/* Issue a read status instruction and read previous conversion data */
	return adc12138_mode_programming(adc, ADC12138_MODE_READ_STATUS,
	value, sizeof(*value));
	}

	static int adc12138_wait_eoc(struct adc12138 *adc, unsigned long timeout)
	{
	if (!wait_for_completion_timeout(&adc->complete, timeout))
	return -ETIMEDOUT;

	return 0;
	}

	static int adc12138_adc_conversion(struct adc12138 *adc,
	struct iio_chan_spec const *channel,
	__be16 *value)
	{
	int ret;

	reinit_completion(&adc->complete);

	ret = adc12138_start_conv(adc, channel);
	if (ret)
	return ret;

	ret = adc12138_wait_eoc(adc, msecs_to_jiffies(100));
	if (ret)
	return ret;

	return adc12138_read_conv_data(adc, value);
	}

	static int adc12138_read_raw(struct iio_dev *iio,
	struct iio_chan_spec const channel, int value,
	int *shift, long mask)
	{
	struct adc12138 *adc = iio_priv(iio);
	int ret;
	__be16 data;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	mutex_lock(&adc->lock);
	ret = adc12138_adc_conversion(adc, channel, &data);
	mutex_unlock(&adc->lock);
	if (ret)
	return ret;

	*value = sign_extend32(be16_to_cpu(data) >> 3, 12);

	return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
	ret = regulator_get_voltage(adc->vref_p);
	if (ret < 0)
	return ret;
	*value = ret;

	if (!IS_ERR(adc->vref_n)) {
	ret = regulator_get_voltage(adc->vref_n);
	if (ret < 0)
	return ret;
	*value -= ret;
	}

	/* convert regulator output voltage to mV */
	*value /= 1000;
	*shift = channel->scan_type.realbits - 1;

	return IIO_VAL_FRACTIONAL_LOG2;
	case IIO_CHAN_INFO_OFFSET:
	if (!IS_ERR(adc->vref_n)) {
	*value = regulator_get_voltage(adc->vref_n);
	if (*value < 0)
	return *value;
	} else {
	*value = 0;
	}

	/* convert regulator output voltage to mV */
	*value /= 1000;

	return IIO_VAL_INT;
	}

	return -EINVAL;
	}

	static const struct iio_info adc12138_info = {
	.read_raw = adc12138_read_raw,
	};

	static int adc12138_init(struct adc12138 *adc)
	{
	int ret;
	int status;
	u8 mode;
	u8 trash;

	reinit_completion(&adc->complete);

	ret = adc12138_mode_programming(adc, ADC12138_MODE_AUTO_CAL, &trash, 1);
	if (ret)
	return ret;

	/* data output at this time has no significance */
	status = adc12138_read_status(adc);
	if (status < 0)
	return status;

	adc12138_wait_eoc(adc, msecs_to_jiffies(100));

	status = adc12138_read_status(adc);
	if (status & ADC12138_STATUS_CAL) {
	dev_warn(&adc->spi->dev,
	"Auto Cal sequence is still in progress: %#x\n",
	status);
	return -EIO;
	}

	switch (adc->acquisition_time) {
	case 6:
	mode = ADC12138_MODE_ACQUISITION_TIME_6;
	break;
	case 10:
	mode = ADC12138_MODE_ACQUISITION_TIME_10;
	break;
	case 18:
	mode = ADC12138_MODE_ACQUISITION_TIME_18;
	break;
	case 34:
	mode = ADC12138_MODE_ACQUISITION_TIME_34;
	break;
	default:
	return -EINVAL;
	}

	return adc12138_mode_programming(adc, mode, &trash, 1);
	}

	static irqreturn_t adc12138_trigger_handler(int irq, void *p)
	{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct adc12138 *adc = iio_priv(indio_dev);
	__be16 trash;
	int ret;
	int scan_index;
	int i = 0;

	mutex_lock(&adc->lock);

	for_each_set_bit(scan_index, indio_dev->active_scan_mask,
	indio_dev->masklength) {
	const struct iio_chan_spec *scan_chan =
	&indio_dev->channels[scan_index];

	reinit_completion(&adc->complete);

	ret = adc12138_start_and_read_conv(adc, scan_chan,
	i ? &adc->data[i - 1] : &trash);
	if (ret) {
	dev_warn(&adc->spi->dev,
	"failed to start conversion\n");
	goto out;
	}

	ret = adc12138_wait_eoc(adc, msecs_to_jiffies(100));
	if (ret) {
	dev_warn(&adc->spi->dev, "wait eoc timeout\n");
	goto out;
	}

	i++;
	}

	if (i) {
	ret = adc12138_read_conv_data(adc, &adc->data[i - 1]);
	if (ret) {
	dev_warn(&adc->spi->dev,
	"failed to get conversion data\n");
	goto out;
	}
	}

	iio_push_to_buffers_with_timestamp(indio_dev, adc->data,
	iio_get_time_ns(indio_dev));
	out:
	mutex_unlock(&adc->lock);

	iio_trigger_notify_done(indio_dev->trig);

	return IRQ_HANDLED;
	}

	static irqreturn_t adc12138_eoc_handler(int irq, void *p)
	{
	struct iio_dev *indio_dev = p;
	struct adc12138 *adc = iio_priv(indio_dev);

	complete(&adc->complete);

	return IRQ_HANDLED;
	}

	static int adc12138_probe(struct spi_device *spi)
	{
	struct iio_dev *indio_dev;
	struct adc12138 *adc;
	int ret;

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

	adc = iio_priv(indio_dev);
	adc->spi = spi;
	adc->id = spi_get_device_id(spi)->driver_data;
	mutex_init(&adc->lock);
	init_completion(&adc->complete);

	indio_dev->name = spi_get_device_id(spi)->name;
	indio_dev->dev.parent = &spi->dev;
	indio_dev->info = &adc12138_info;
	indio_dev->modes = INDIO_DIRECT_MODE;

	switch (adc->id) {
	case adc12130:
	case adc12132:
	indio_dev->channels = adc12132_channels;
	indio_dev->num_channels = ARRAY_SIZE(adc12132_channels);
	break;
	case adc12138:
	indio_dev->channels = adc12138_channels;
	indio_dev->num_channels = ARRAY_SIZE(adc12138_channels);
	break;
	default:
	return -EINVAL;
	}

	ret = of_property_read_u32(spi->dev.of_node, "ti,acquisition-time",
	&adc->acquisition_time);
	if (ret)
	adc->acquisition_time = 10;

	adc->cclk = devm_clk_get(&spi->dev, NULL);
	if (IS_ERR(adc->cclk))
	return PTR_ERR(adc->cclk);

	adc->vref_p = devm_regulator_get(&spi->dev, "vref-p");
	if (IS_ERR(adc->vref_p))
	return PTR_ERR(adc->vref_p);

	adc->vref_n = devm_regulator_get_optional(&spi->dev, "vref-n");
	if (IS_ERR(adc->vref_n)) {
	/*
	* Assume vref_n is 0V if an optional regulator is not
	* specified, otherwise return the error code.
	*/
	ret = PTR_ERR(adc->vref_n);
	if (ret != -ENODEV)
	return ret;
	}

	ret = devm_request_irq(&spi->dev, spi->irq, adc12138_eoc_handler,
	IRQF_TRIGGER_RISING, indio_dev->name, indio_dev);
	if (ret)
	return ret;

	ret = clk_prepare_enable(adc->cclk);
	if (ret)
	return ret;

	ret = regulator_enable(adc->vref_p);
	if (ret)
	goto err_clk_disable;

	if (!IS_ERR(adc->vref_n)) {
	ret = regulator_enable(adc->vref_n);
	if (ret)
	goto err_vref_p_disable;
	}

	ret = adc12138_init(adc);
	if (ret)
	goto err_vref_n_disable;

	spi_set_drvdata(spi, indio_dev);

	ret = iio_triggered_buffer_setup(indio_dev, NULL,
	adc12138_trigger_handler, NULL);
	if (ret)
	goto err_vref_n_disable;

	ret = iio_device_register(indio_dev);
	if (ret)
	goto err_buffer_cleanup;

	return 0;
	err_buffer_cleanup:
	iio_triggered_buffer_cleanup(indio_dev);
	err_vref_n_disable:
	if (!IS_ERR(adc->vref_n))
	regulator_disable(adc->vref_n);
	err_vref_p_disable:
	regulator_disable(adc->vref_p);
	err_clk_disable:
	clk_disable_unprepare(adc->cclk);

	return ret;
	}

	static int adc12138_remove(struct spi_device *spi)
	{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);
	struct adc12138 *adc = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);
	iio_triggered_buffer_cleanup(indio_dev);
	if (!IS_ERR(adc->vref_n))
	regulator_disable(adc->vref_n);
	regulator_disable(adc->vref_p);
	clk_disable_unprepare(adc->cclk);

	return 0;
	}

	#ifdef CONFIG_OF

	static const struct of_device_id adc12138_dt_ids[] = {
	{ .compatible = "ti,adc12130", },
	{ .compatible = "ti,adc12132", },
	{ .compatible = "ti,adc12138", },
	{}
	};
	MODULE_DEVICE_TABLE(of, adc12138_dt_ids);

	#endif

	static const struct spi_device_id adc12138_id[] = {
	{ "adc12130", adc12130 },
	{ "adc12132", adc12132 },
	{ "adc12138", adc12138 },
	{}
	};
	MODULE_DEVICE_TABLE(spi, adc12138_id);

	static struct spi_driver adc12138_driver = {
	.driver = {
	.name = "adc12138",
	.of_match_table = of_match_ptr(adc12138_dt_ids),
	},
	.probe = adc12138_probe,
	.remove = adc12138_remove,
	.id_table = adc12138_id,
	};
	module_spi_driver(adc12138_driver);

	MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
	MODULE_DESCRIPTION("ADC12130/ADC12132/ADC12138 driver");
	MODULE_LICENSE("GPL v2");