/*
   * AD7887 SPI ADC driver
   *
   * Copyright 2010-2011 Analog Devices Inc.
   *
   * Licensed under the GPL-2.
   */
  
  #include <linux/device.h>
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/sysfs.h>
  #include <linux/spi/spi.h>
  #include <linux/regulator/consumer.h>
  #include <linux/err.h>
  #include <linux/module.h>
  #include <linux/interrupt.h>
  #include <linux/bitops.h>
  
  #include <linux/iio/iio.h>
  #include <linux/iio/sysfs.h>
  #include <linux/iio/buffer.h>
  
  #include <linux/iio/trigger_consumer.h>
  #include <linux/iio/triggered_buffer.h>
  
  #include <linux/platform_data/ad7887.h>
  
  #define AD7887_REF_DIS		BIT(5)	/* on-chip reference disable */
  #define AD7887_DUAL		BIT(4)	/* dual-channel mode */
  #define AD7887_CH_AIN1		BIT(3)	/* convert on channel 1, DUAL=1 */
  #define AD7887_CH_AIN0		0	/* convert on channel 0, DUAL=0,1 */
  #define AD7887_PM_MODE1		0	/* CS based shutdown */
  #define AD7887_PM_MODE2		1	/* full on */
  #define AD7887_PM_MODE3		2	/* auto shutdown after conversion */
  #define AD7887_PM_MODE4		3	/* standby mode */
  
  enum ad7887_channels {
  	AD7887_CH0,
  	AD7887_CH0_CH1,
  	AD7887_CH1,
  };
  
  /**
   * struct ad7887_chip_info - chip specifc information
   * @int_vref_mv:	the internal reference voltage
   * @channel:		channel specification
   */
  struct ad7887_chip_info {
  	u16				int_vref_mv;
  	struct iio_chan_spec		channel[3];
  };
  
  struct ad7887_state {
  	struct spi_device		*spi;
  	const struct ad7887_chip_info	*chip_info;
  	struct regulator		*reg;
  	struct spi_transfer		xfer[4];
  	struct spi_message		msg[3];
  	struct spi_message		*ring_msg;
  	unsigned char			tx_cmd_buf[4];
  
  	/*
  	 * DMA (thus cache coherency maintenance) requires the
  	 * transfer buffers to live in their own cache lines.
  	 * Buffer needs to be large enough to hold two 16 bit samples and a
  	 * 64 bit aligned 64 bit timestamp.
  	 */
  	unsigned char data[ALIGN(4, sizeof(s64)) + sizeof(s64)]
  		____cacheline_aligned;
  };
  
  enum ad7887_supported_device_ids {
  	ID_AD7887
  };
  
  static int ad7887_ring_preenable(struct iio_dev *indio_dev)
  {
  	struct ad7887_state *st = iio_priv(indio_dev);
  
  	/* We know this is a single long so can 'cheat' */
  	switch (*indio_dev->active_scan_mask) {
  	case (1 << 0):
  		st->ring_msg = &st->msg[AD7887_CH0];
  		break;
  	case (1 << 1):
  		st->ring_msg = &st->msg[AD7887_CH1];
  		/* Dummy read: push CH1 setting down to hardware */
  		spi_sync(st->spi, st->ring_msg);
  		break;
  	case ((1 << 1) | (1 << 0)):
  		st->ring_msg = &st->msg[AD7887_CH0_CH1];
  		break;
  	}
  
  	return 0;
  }
  
  static int ad7887_ring_postdisable(struct iio_dev *indio_dev)
  {
  	struct ad7887_state *st = iio_priv(indio_dev);
  
  	/* dummy read: restore default CH0 settin */
  	return spi_sync(st->spi, &st->msg[AD7887_CH0]);
  }
  
  /**
   * ad7887_trigger_handler() bh of trigger launched polling to ring buffer
   *
   * Currently there is no option in this driver to disable the saving of
   * timestamps within the ring.
   **/
  static irqreturn_t ad7887_trigger_handler(int irq, void *p)
  {
  	struct iio_poll_func *pf = p;
  	struct iio_dev *indio_dev = pf->indio_dev;
  	struct ad7887_state *st = iio_priv(indio_dev);
  	int b_sent;
  
  	b_sent = spi_sync(st->spi, st->ring_msg);
  	if (b_sent)
  		goto done;
  
  	iio_push_to_buffers_with_timestamp(indio_dev, st->data,
  		iio_get_time_ns());
  done:
  	iio_trigger_notify_done(indio_dev->trig);
  
  	return IRQ_HANDLED;
  }
  
  static const struct iio_buffer_setup_ops ad7887_ring_setup_ops = {
  	.preenable = &ad7887_ring_preenable,
  	.postenable = &iio_triggered_buffer_postenable,
  	.predisable = &iio_triggered_buffer_predisable,
  	.postdisable = &ad7887_ring_postdisable,
  };
  
  static int ad7887_scan_direct(struct ad7887_state *st, unsigned ch)
  {
  	int ret = spi_sync(st->spi, &st->msg[ch]);
  	if (ret)
  		return ret;
  
  	return (st->data[(ch * 2)] << 8) | st->data[(ch * 2) + 1];
  }
  
  static int ad7887_read_raw(struct iio_dev *indio_dev,
  			   struct iio_chan_spec const *chan,
  			   int *val,
  			   int *val2,
  			   long m)
  {
  	int ret;
  	struct ad7887_state *st = iio_priv(indio_dev);
  
  	switch (m) {
  	case IIO_CHAN_INFO_RAW:
  		mutex_lock(&indio_dev->mlock);
  		if (iio_buffer_enabled(indio_dev))
  			ret = -EBUSY;
  		else
  			ret = ad7887_scan_direct(st, chan->address);
  		mutex_unlock(&indio_dev->mlock);
  
  		if (ret < 0)
  			return ret;
  		*val = ret >> chan->scan_type.shift;
  		*val &= GENMASK(chan->scan_type.realbits - 1, 0);
  		return IIO_VAL_INT;
  	case IIO_CHAN_INFO_SCALE:
  		if (st->reg) {
  			*val = regulator_get_voltage(st->reg);
  			if (*val < 0)
  				return *val;
  			*val /= 1000;
  		} else {
  			*val = st->chip_info->int_vref_mv;
  		}
  
  		*val2 = chan->scan_type.realbits;
  
  		return IIO_VAL_FRACTIONAL_LOG2;
  	}
  	return -EINVAL;
  }
  
  
  static const struct ad7887_chip_info ad7887_chip_info_tbl[] = {
  	/*
  	 * More devices added in future
  	 */
  	[ID_AD7887] = {
  		.channel[0] = {
  			.type = IIO_VOLTAGE,
  			.indexed = 1,
  			.channel = 1,
  			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
  			.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
  			.address = 1,
  			.scan_index = 1,
  			.scan_type = {
  				.sign = 'u',
  				.realbits = 12,
  				.storagebits = 16,
  				.shift = 0,
  				.endianness = IIO_BE,
  			},
  		},
  		.channel[1] = {
  			.type = IIO_VOLTAGE,
  			.indexed = 1,
  			.channel = 0,
  			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
  			.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
  			.address = 0,
  			.scan_index = 0,
  			.scan_type = {
  				.sign = 'u',
  				.realbits = 12,
  				.storagebits = 16,
  				.shift = 0,
  				.endianness = IIO_BE,
  			},
  		},
  		.channel[2] = IIO_CHAN_SOFT_TIMESTAMP(2),
  		.int_vref_mv = 2500,
  	},
  };
  
  static const struct iio_info ad7887_info = {
  	.read_raw = &ad7887_read_raw,
  	.driver_module = THIS_MODULE,
  };
  
  static int ad7887_probe(struct spi_device *spi)
  {
  	struct ad7887_platform_data *pdata = spi->dev.platform_data;
  	struct ad7887_state *st;
  	struct iio_dev *indio_dev;
  	uint8_t mode;
  	int ret;
  
  	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
  	if (indio_dev == NULL)
  		return -ENOMEM;
  
  	st = iio_priv(indio_dev);
  
  	if (!pdata || !pdata->use_onchip_ref) {
  		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)
  			return ret;
  	}
  
  	st->chip_info =
  		&ad7887_chip_info_tbl[spi_get_device_id(spi)->driver_data];
  
  	spi_set_drvdata(spi, indio_dev);
  	st->spi = spi;
  
  	/* Estabilish that the iio_dev is a child of the spi device */
  	indio_dev->dev.parent = &spi->dev;
  	indio_dev->name = spi_get_device_id(spi)->name;
  	indio_dev->info = &ad7887_info;
  	indio_dev->modes = INDIO_DIRECT_MODE;
  
  	/* Setup default message */
  
  	mode = AD7887_PM_MODE4;
  	if (!pdata || !pdata->use_onchip_ref)
  		mode |= AD7887_REF_DIS;
  	if (pdata && pdata->en_dual)
  		mode |= AD7887_DUAL;
  
  	st->tx_cmd_buf[0] = AD7887_CH_AIN0 | mode;
  
  	st->xfer[0].rx_buf = &st->data[0];
  	st->xfer[0].tx_buf = &st->tx_cmd_buf[0];
  	st->xfer[0].len = 2;
  
  	spi_message_init(&st->msg[AD7887_CH0]);
  	spi_message_add_tail(&st->xfer[0], &st->msg[AD7887_CH0]);
  
  	if (pdata && pdata->en_dual) {
  		st->tx_cmd_buf[2] = AD7887_CH_AIN1 | mode;
  
  		st->xfer[1].rx_buf = &st->data[0];
  		st->xfer[1].tx_buf = &st->tx_cmd_buf[2];
  		st->xfer[1].len = 2;
  
  		st->xfer[2].rx_buf = &st->data[2];
  		st->xfer[2].tx_buf = &st->tx_cmd_buf[0];
  		st->xfer[2].len = 2;
  
  		spi_message_init(&st->msg[AD7887_CH0_CH1]);
  		spi_message_add_tail(&st->xfer[1], &st->msg[AD7887_CH0_CH1]);
  		spi_message_add_tail(&st->xfer[2], &st->msg[AD7887_CH0_CH1]);
  
  		st->xfer[3].rx_buf = &st->data[2];
  		st->xfer[3].tx_buf = &st->tx_cmd_buf[2];
  		st->xfer[3].len = 2;
  
  		spi_message_init(&st->msg[AD7887_CH1]);
  		spi_message_add_tail(&st->xfer[3], &st->msg[AD7887_CH1]);
  
  		indio_dev->channels = st->chip_info->channel;
  		indio_dev->num_channels = 3;
  	} else {
  		indio_dev->channels = &st->chip_info->channel[1];
  		indio_dev->num_channels = 2;
  	}
  
  	ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
  			&ad7887_trigger_handler, &ad7887_ring_setup_ops);
  	if (ret)
  		goto error_disable_reg;
  
  	ret = iio_device_register(indio_dev);
  	if (ret)
  		goto error_unregister_ring;
  
  	return 0;
  error_unregister_ring:
  	iio_triggered_buffer_cleanup(indio_dev);
  error_disable_reg:
  	if (st->reg)
  		regulator_disable(st->reg);
  
  	return ret;
  }
  
  static int ad7887_remove(struct spi_device *spi)
  {
  	struct iio_dev *indio_dev = spi_get_drvdata(spi);
  	struct ad7887_state *st = iio_priv(indio_dev);
  
  	iio_device_unregister(indio_dev);
  	iio_triggered_buffer_cleanup(indio_dev);
  	if (st->reg)
  		regulator_disable(st->reg);
  
  	return 0;
  }
  
  static const struct spi_device_id ad7887_id[] = {
  	{"ad7887", ID_AD7887},
  	{}
  };
  MODULE_DEVICE_TABLE(spi, ad7887_id);
  
  static struct spi_driver ad7887_driver = {
  	.driver = {
  		.name	= "ad7887",
  	},
  	.probe		= ad7887_probe,
  	.remove		= ad7887_remove,
  	.id_table	= ad7887_id,
  };
  module_spi_driver(ad7887_driver);
  
  MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
  MODULE_DESCRIPTION("Analog Devices AD7887 ADC");
  MODULE_LICENSE("GPL v2");