/*
   * Copyright (C) 2013 Oskar Andero <oskar.andero@gmail.com>
   * Copyright (C) 2014 Rose Technology
   * 	   Allan Bendorff Jensen <abj@rosetechnology.dk>
   *	   Soren Andersen <san@rosetechnology.dk>
   *
   * Driver for following ADC chips from Microchip Technology's:
   * 10 Bit converter
   * MCP3001
   * MCP3002
   * MCP3004
   * MCP3008
   * ------------
   * 12 bit converter
   * MCP3201
   * MCP3202
   * MCP3204
   * MCP3208
   * ------------
   *
   * Datasheet can be found here:
   * http://ww1.microchip.com/downloads/en/DeviceDoc/21293C.pdf  mcp3001
   * http://ww1.microchip.com/downloads/en/DeviceDoc/21294E.pdf  mcp3002
   * http://ww1.microchip.com/downloads/en/DeviceDoc/21295d.pdf  mcp3004/08
   * http://ww1.microchip.com/downloads/en/DeviceDoc/21290D.pdf  mcp3201
   * http://ww1.microchip.com/downloads/en/DeviceDoc/21034D.pdf  mcp3202
   * http://ww1.microchip.com/downloads/en/DeviceDoc/21298c.pdf  mcp3204/08
   * http://ww1.microchip.com/downloads/en/DeviceDoc/21700E.pdf  mcp3301
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #include <linux/err.h>
  #include <linux/delay.h>
  #include <linux/spi/spi.h>
  #include <linux/module.h>
  #include <linux/iio/iio.h>
  #include <linux/regulator/consumer.h>
  
  enum {
  	mcp3001,
  	mcp3002,
  	mcp3004,
  	mcp3008,
  	mcp3201,
  	mcp3202,
  	mcp3204,
  	mcp3208,
  	mcp3301,
  };
  
  struct mcp320x_chip_info {
  	const struct iio_chan_spec *channels;
  	unsigned int num_channels;
  	unsigned int resolution;
  };
  
  struct mcp320x {
  	struct spi_device *spi;
  	struct spi_message msg;
  	struct spi_transfer transfer[2];
  
  	struct regulator *reg;
  	struct mutex lock;
  	const struct mcp320x_chip_info *chip_info;
  
  	u8 tx_buf ____cacheline_aligned;
  	u8 rx_buf[2];
  };
  
  static int mcp320x_channel_to_tx_data(int device_index,
  			const unsigned int channel, bool differential)
  {
  	int start_bit = 1;
  
  	switch (device_index) {
  	case mcp3001:
  	case mcp3201:
  	case mcp3301:
  		return 0;
  	case mcp3002:
  	case mcp3202:
  		return ((start_bit << 4) | (!differential << 3) |
  							(channel << 2));
  	case mcp3004:
  	case mcp3204:
  	case mcp3008:
  	case mcp3208:
  		return ((start_bit << 6) | (!differential << 5) |
  							(channel << 2));
  	default:
  		return -EINVAL;
  	}
  }
  
  static int mcp320x_adc_conversion(struct mcp320x *adc, u8 channel,
  				  bool differential, int device_index)
  {
  	int ret;
  
  	adc->rx_buf[0] = 0;
  	adc->rx_buf[1] = 0;
  	adc->tx_buf = mcp320x_channel_to_tx_data(device_index,
  						channel, differential);
  
  	if (device_index != mcp3001 && device_index != mcp3201 && device_index != mcp3301) {
  		ret = spi_sync(adc->spi, &adc->msg);
  		if (ret < 0)
  			return ret;
  	} else {
  		ret = spi_read(adc->spi, &adc->rx_buf, sizeof(adc->rx_buf));
  		if (ret < 0)
  			return ret;
  	}
  
  	switch (device_index) {
  	case mcp3001:
  		return (adc->rx_buf[0] << 5 | adc->rx_buf[1] >> 3);
  	case mcp3002:
  	case mcp3004:
  	case mcp3008:
  		return (adc->rx_buf[0] << 2 | adc->rx_buf[1] >> 6);
  	case mcp3201:
  		return (adc->rx_buf[0] << 7 | adc->rx_buf[1] >> 1);
  	case mcp3202:
  	case mcp3204:
  	case mcp3208:
  		return (adc->rx_buf[0] << 4 | adc->rx_buf[1] >> 4);
  	case mcp3301:
  		return sign_extend32((adc->rx_buf[0] & 0x1f) << 8 | adc->rx_buf[1], 12);
  	default:
  		return -EINVAL;
  	}
  }
  
  static int mcp320x_read_raw(struct iio_dev *indio_dev,
  			    struct iio_chan_spec const *channel, int *val,
  			    int *val2, long mask)
  {
  	struct mcp320x *adc = iio_priv(indio_dev);
  	int ret = -EINVAL;
  	int device_index = 0;
  
  	mutex_lock(&adc->lock);
  
  	device_index = spi_get_device_id(adc->spi)->driver_data;
  
  	switch (mask) {
  	case IIO_CHAN_INFO_RAW:
  		ret = mcp320x_adc_conversion(adc, channel->address,
  			channel->differential, device_index);
  
  		if (ret < 0)
  			goto out;
  
  		*val = ret;
  		ret = IIO_VAL_INT;
  		break;
  
  	case IIO_CHAN_INFO_SCALE:
  		ret = regulator_get_voltage(adc->reg);
  		if (ret < 0)
  			goto out;
  
  		/* convert regulator output voltage to mV */
  		*val = ret / 1000;
  		*val2 = adc->chip_info->resolution;
  		ret = IIO_VAL_FRACTIONAL_LOG2;
  		break;
  	}
  
  out:
  	mutex_unlock(&adc->lock);
  
  	return ret;
  }
  
  #define MCP320X_VOLTAGE_CHANNEL(num)				\
  	{							\
  		.type = IIO_VOLTAGE,				\
  		.indexed = 1,					\
  		.channel = (num),				\
  		.address = (num),				\
  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
  		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
  	}
  
  #define MCP320X_VOLTAGE_CHANNEL_DIFF(num)			\
  	{							\
  		.type = IIO_VOLTAGE,				\
  		.indexed = 1,					\
  		.channel = (num * 2),				\
  		.channel2 = (num * 2 + 1),			\
  		.address = (num * 2),				\
  		.differential = 1,				\
  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
  		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
  	}
  
  static const struct iio_chan_spec mcp3201_channels[] = {
  	MCP320X_VOLTAGE_CHANNEL_DIFF(0),
  };
  
  static const struct iio_chan_spec mcp3202_channels[] = {
  	MCP320X_VOLTAGE_CHANNEL(0),
  	MCP320X_VOLTAGE_CHANNEL(1),
  	MCP320X_VOLTAGE_CHANNEL_DIFF(0),
  };
  
  static const struct iio_chan_spec mcp3204_channels[] = {
  	MCP320X_VOLTAGE_CHANNEL(0),
  	MCP320X_VOLTAGE_CHANNEL(1),
  	MCP320X_VOLTAGE_CHANNEL(2),
  	MCP320X_VOLTAGE_CHANNEL(3),
  	MCP320X_VOLTAGE_CHANNEL_DIFF(0),
  	MCP320X_VOLTAGE_CHANNEL_DIFF(1),
  };
  
  static const struct iio_chan_spec mcp3208_channels[] = {
  	MCP320X_VOLTAGE_CHANNEL(0),
  	MCP320X_VOLTAGE_CHANNEL(1),
  	MCP320X_VOLTAGE_CHANNEL(2),
  	MCP320X_VOLTAGE_CHANNEL(3),
  	MCP320X_VOLTAGE_CHANNEL(4),
  	MCP320X_VOLTAGE_CHANNEL(5),
  	MCP320X_VOLTAGE_CHANNEL(6),
  	MCP320X_VOLTAGE_CHANNEL(7),
  	MCP320X_VOLTAGE_CHANNEL_DIFF(0),
  	MCP320X_VOLTAGE_CHANNEL_DIFF(1),
  	MCP320X_VOLTAGE_CHANNEL_DIFF(2),
  	MCP320X_VOLTAGE_CHANNEL_DIFF(3),
  };
  
  static const struct iio_info mcp320x_info = {
  	.read_raw = mcp320x_read_raw,
  	.driver_module = THIS_MODULE,
  };
  
  static const struct mcp320x_chip_info mcp320x_chip_infos[] = {
  	[mcp3001] = {
  		.channels = mcp3201_channels,
  		.num_channels = ARRAY_SIZE(mcp3201_channels),
  		.resolution = 10
  	},
  	[mcp3002] = {
  		.channels = mcp3202_channels,
  		.num_channels = ARRAY_SIZE(mcp3202_channels),
  		.resolution = 10
  	},
  	[mcp3004] = {
  		.channels = mcp3204_channels,
  		.num_channels = ARRAY_SIZE(mcp3204_channels),
  		.resolution = 10
  	},
  	[mcp3008] = {
  		.channels = mcp3208_channels,
  		.num_channels = ARRAY_SIZE(mcp3208_channels),
  		.resolution = 10
  	},
  	[mcp3201] = {
  		.channels = mcp3201_channels,
  		.num_channels = ARRAY_SIZE(mcp3201_channels),
  		.resolution = 12
  	},
  	[mcp3202] = {
  		.channels = mcp3202_channels,
  		.num_channels = ARRAY_SIZE(mcp3202_channels),
  		.resolution = 12
  	},
  	[mcp3204] = {
  		.channels = mcp3204_channels,
  		.num_channels = ARRAY_SIZE(mcp3204_channels),
  		.resolution = 12
  	},
  	[mcp3208] = {
  		.channels = mcp3208_channels,
  		.num_channels = ARRAY_SIZE(mcp3208_channels),
  		.resolution = 12
  	},
  	[mcp3301] = {
  		.channels = mcp3201_channels,
  		.num_channels = ARRAY_SIZE(mcp3201_channels),
  		.resolution = 13
  	},
  };
  
  static int mcp320x_probe(struct spi_device *spi)
  {
  	struct iio_dev *indio_dev;
  	struct mcp320x *adc;
  	const struct mcp320x_chip_info *chip_info;
  	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;
  
  	indio_dev->dev.parent = &spi->dev;
  	indio_dev->name = spi_get_device_id(spi)->name;
  	indio_dev->modes = INDIO_DIRECT_MODE;
  	indio_dev->info = &mcp320x_info;
  
  	chip_info = &mcp320x_chip_infos[spi_get_device_id(spi)->driver_data];
  	indio_dev->channels = chip_info->channels;
  	indio_dev->num_channels = chip_info->num_channels;
  
  	adc->chip_info = chip_info;
  
  	adc->transfer[0].tx_buf = &adc->tx_buf;
  	adc->transfer[0].len = sizeof(adc->tx_buf);
  	adc->transfer[1].rx_buf = adc->rx_buf;
  	adc->transfer[1].len = sizeof(adc->rx_buf);
  
  	spi_message_init_with_transfers(&adc->msg, adc->transfer,
  					ARRAY_SIZE(adc->transfer));
  
  	adc->reg = devm_regulator_get(&spi->dev, "vref");
  	if (IS_ERR(adc->reg))
  		return PTR_ERR(adc->reg);
  
  	ret = regulator_enable(adc->reg);
  	if (ret < 0)
  		return ret;
  
  	mutex_init(&adc->lock);
  
  	ret = iio_device_register(indio_dev);
  	if (ret < 0)
  		goto reg_disable;
  
  	return 0;
  
  reg_disable:
  	regulator_disable(adc->reg);
  
  	return ret;
  }
  
  static int mcp320x_remove(struct spi_device *spi)
  {
  	struct iio_dev *indio_dev = spi_get_drvdata(spi);
  	struct mcp320x *adc = iio_priv(indio_dev);
  
  	iio_device_unregister(indio_dev);
  	regulator_disable(adc->reg);
  
  	return 0;
  }
  
  #if defined(CONFIG_OF)
  static const struct of_device_id mcp320x_dt_ids[] = {
  	{
  		.compatible = "mcp3001",
  		.data = &mcp320x_chip_infos[mcp3001],
  	}, {
  		.compatible = "mcp3002",
  		.data = &mcp320x_chip_infos[mcp3002],
  	}, {
  		.compatible = "mcp3004",
  		.data = &mcp320x_chip_infos[mcp3004],
  	}, {
  		.compatible = "mcp3008",
  		.data = &mcp320x_chip_infos[mcp3008],
  	}, {
  		.compatible = "mcp3201",
  		.data = &mcp320x_chip_infos[mcp3201],
  	}, {
  		.compatible = "mcp3202",
  		.data = &mcp320x_chip_infos[mcp3202],
  	}, {
  		.compatible = "mcp3204",
  		.data = &mcp320x_chip_infos[mcp3204],
  	}, {
  		.compatible = "mcp3208",
  		.data = &mcp320x_chip_infos[mcp3208],
  	}, {
  		.compatible = "mcp3301",
  		.data = &mcp320x_chip_infos[mcp3301],
  	}, {
  	}
  };
  MODULE_DEVICE_TABLE(of, mcp320x_dt_ids);
  #endif
  
  static const struct spi_device_id mcp320x_id[] = {
  	{ "mcp3001", mcp3001 },
  	{ "mcp3002", mcp3002 },
  	{ "mcp3004", mcp3004 },
  	{ "mcp3008", mcp3008 },
  	{ "mcp3201", mcp3201 },
  	{ "mcp3202", mcp3202 },
  	{ "mcp3204", mcp3204 },
  	{ "mcp3208", mcp3208 },
  	{ "mcp3301", mcp3301 },
  	{ }
  };
  MODULE_DEVICE_TABLE(spi, mcp320x_id);
  
  static struct spi_driver mcp320x_driver = {
  	.driver = {
  		.name = "mcp320x",
  		.of_match_table = of_match_ptr(mcp320x_dt_ids),
  	},
  	.probe = mcp320x_probe,
  	.remove = mcp320x_remove,
  	.id_table = mcp320x_id,
  };
  module_spi_driver(mcp320x_driver);
  
  MODULE_AUTHOR("Oskar Andero <oskar.andero@gmail.com>");
  MODULE_DESCRIPTION("Microchip Technology MCP3x01/02/04/08");
  MODULE_LICENSE("GPL v2");