text: /*
   * AD5686R, AD5685R, AD5684R Digital to analog converters  driver
   *
   * Copyright 2011 Analog Devices Inc.
   *
   * Licensed under the GPL-2.
   */
  
  #include <linux/interrupt.h>
  #include <linux/fs.h>
  #include <linux/device.h>
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/spi/spi.h>
  #include <linux/slab.h>
  #include <linux/sysfs.h>
  #include <linux/regulator/consumer.h>
  
  #include <linux/iio/iio.h>
  #include <linux/iio/sysfs.h>
  
  #define AD5686_DAC_CHANNELS			4
  
  #define AD5686_ADDR(x)				((x) << 16)
  #define AD5686_CMD(x)				((x) << 20)
  
  #define AD5686_ADDR_DAC(chan)		(0x1 << (chan))
  #define AD5686_ADDR_ALL_DAC			0xF
  
  #define AD5686_CMD_NOOP				0x0
  #define AD5686_CMD_WRITE_INPUT_N		0x1
  #define AD5686_CMD_UPDATE_DAC_N			0x2
  #define AD5686_CMD_WRITE_INPUT_N_UPDATE_N	0x3
  #define AD5686_CMD_POWERDOWN_DAC		0x4
  #define AD5686_CMD_LDAC_MASK			0x5
  #define AD5686_CMD_RESET			0x6
  #define AD5686_CMD_INTERNAL_REFER_SETUP		0x7
  #define AD5686_CMD_DAISY_CHAIN_ENABLE		0x8
  #define AD5686_CMD_READBACK_ENABLE		0x9
  
  #define AD5686_LDAC_PWRDN_NONE			0x0
  #define AD5686_LDAC_PWRDN_1K			0x1
  #define AD5686_LDAC_PWRDN_100K			0x2
  #define AD5686_LDAC_PWRDN_3STATE		0x3
  
  /**
   * struct ad5686_chip_info - chip specific information
   * @int_vref_mv:	AD5620/40/60: the internal reference voltage
   * @channel:		channel specification
  */
  
  struct ad5686_chip_info {
  	u16				int_vref_mv;
  	struct iio_chan_spec		channel[AD5686_DAC_CHANNELS];
  };
  
  /**
   * struct ad5446_state - driver instance specific data
   * @spi:		spi_device
   * @chip_info:		chip model specific constants, available modes etc
   * @reg:		supply regulator
   * @vref_mv:		actual reference voltage used
   * @pwr_down_mask:	power down mask
   * @pwr_down_mode:	current power down mode
   * @data:		spi transfer buffers
   */
  
  struct ad5686_state {
  	struct spi_device		*spi;
  	const struct ad5686_chip_info	*chip_info;
  	struct regulator		*reg;
  	unsigned short			vref_mv;
  	unsigned			pwr_down_mask;
  	unsigned			pwr_down_mode;
  	/*
  	 * 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;
  };
  
  /**
   * ad5686_supported_device_ids:
   */
  
  enum ad5686_supported_device_ids {
  	ID_AD5684,
  	ID_AD5685,
  	ID_AD5686,
  };
  static int ad5686_spi_write(struct ad5686_state *st,
  			     u8 cmd, u8 addr, u16 val, u8 shift)
  {
  	val <<= shift;
  
  	st->data[0].d32 = cpu_to_be32(AD5686_CMD(cmd) |
  			      AD5686_ADDR(addr) |
  			      val);
  
  	return spi_write(st->spi, &st->data[0].d8[1], 3);
  }
  
  static int ad5686_spi_read(struct ad5686_state *st, u8 addr)
  {
  	struct spi_transfer t[] = {
  		{
  			.tx_buf = &st->data[0].d8[1],
  			.len = 3,
  			.cs_change = 1,
  		}, {
  			.tx_buf = &st->data[1].d8[1],
  			.rx_buf = &st->data[2].d8[1],
  			.len = 3,
  		},
  	};
  	int ret;
  
  	st->data[0].d32 = cpu_to_be32(AD5686_CMD(AD5686_CMD_READBACK_ENABLE) |
  			      AD5686_ADDR(addr));
  	st->data[1].d32 = cpu_to_be32(AD5686_CMD(AD5686_CMD_NOOP));
  
  	ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
  	if (ret < 0)
  		return ret;
  
  	return be32_to_cpu(st->data[2].d32);
  }
  
  static const char * const ad5686_powerdown_modes[] = {
  	"1kohm_to_gnd",
  	"100kohm_to_gnd",
  	"three_state"
  };
  
  static int ad5686_get_powerdown_mode(struct iio_dev *indio_dev,
  	const struct iio_chan_spec *chan)
  {
  	struct ad5686_state *st = iio_priv(indio_dev);
  
  	return ((st->pwr_down_mode >> (chan->channel * 2)) & 0x3) - 1;
  }
  
  static int ad5686_set_powerdown_mode(struct iio_dev *indio_dev,
  	const struct iio_chan_spec *chan, unsigned int mode)
  {
  	struct ad5686_state *st = iio_priv(indio_dev);
  
  	st->pwr_down_mode &= ~(0x3 << (chan->channel * 2));
  	st->pwr_down_mode |= ((mode + 1) << (chan->channel * 2));
  
  	return 0;
  }
  
  static const struct iio_enum ad5686_powerdown_mode_enum = {
  	.items = ad5686_powerdown_modes,
  	.num_items = ARRAY_SIZE(ad5686_powerdown_modes),
  	.get = ad5686_get_powerdown_mode,
  	.set = ad5686_set_powerdown_mode,
  };
  
  static ssize_t ad5686_read_dac_powerdown(struct iio_dev *indio_dev,
  	uintptr_t private, const struct iio_chan_spec *chan, char *buf)
  {
  	struct ad5686_state *st = iio_priv(indio_dev);
  
  	return sprintf(buf, "%d\n", !!(st->pwr_down_mask &
  			(0x3 << (chan->channel * 2))));
  }
  
  static ssize_t ad5686_write_dac_powerdown(struct iio_dev *indio_dev,
  	 uintptr_t private, const struct iio_chan_spec *chan, const char *buf,
  	 size_t len)
  {
  	bool readin;
  	int ret;
  	struct ad5686_state *st = iio_priv(indio_dev);
  
  	ret = strtobool(buf, &readin);
  	if (ret)
  		return ret;
  
  	if (readin)
  		st->pwr_down_mask |= (0x3 << (chan->channel * 2));
  	else
  		st->pwr_down_mask &= ~(0x3 << (chan->channel * 2));
  
  	ret = ad5686_spi_write(st, AD5686_CMD_POWERDOWN_DAC, 0,
  			       st->pwr_down_mask & st->pwr_down_mode, 0);
  
  	return ret ? ret : len;
  }
  
  static int ad5686_read_raw(struct iio_dev *indio_dev,
  			   struct iio_chan_spec const *chan,
  			   int *val,
  			   int *val2,
  			   long m)
  {
  	struct ad5686_state *st = iio_priv(indio_dev);
  	int ret;
  
  	switch (m) {
  	case IIO_CHAN_INFO_RAW:
  		mutex_lock(&indio_dev->mlock);
  		ret = ad5686_spi_read(st, chan->address);
  		mutex_unlock(&indio_dev->mlock);
  		if (ret < 0)
  			return ret;
  		*val = ret;
  		return IIO_VAL_INT;
  	case IIO_CHAN_INFO_SCALE:
  		*val = st->vref_mv;
  		*val2 = chan->scan_type.realbits;
  		return IIO_VAL_FRACTIONAL_LOG2;
  	}
  	return -EINVAL;
  }
  
  static int ad5686_write_raw(struct iio_dev *indio_dev,
  			       struct iio_chan_spec const *chan,
  			       int val,
  			       int val2,
  			       long mask)
  {
  	struct ad5686_state *st = iio_priv(indio_dev);
  	int ret;
  
  	switch (mask) {
  	case IIO_CHAN_INFO_RAW:
  		if (val > (1 << chan->scan_type.realbits) || val < 0)
  			return -EINVAL;
  
  		mutex_lock(&indio_dev->mlock);
  		ret = ad5686_spi_write(st,
  				 AD5686_CMD_WRITE_INPUT_N_UPDATE_N,
  				 chan->address,
  				 val,
  				 chan->scan_type.shift);
  		mutex_unlock(&indio_dev->mlock);
  		break;
  	default:
  		ret = -EINVAL;
  	}
  
  	return ret;
  }
  
  static const struct iio_info ad5686_info = {
  	.read_raw = ad5686_read_raw,
  	.write_raw = ad5686_write_raw,
  	.driver_module = THIS_MODULE,
  };
  
  static const struct iio_chan_spec_ext_info ad5686_ext_info[] = {
  	{
  		.name = "powerdown",
  		.read = ad5686_read_dac_powerdown,
  		.write = ad5686_write_dac_powerdown,
  		.shared = IIO_SEPARATE,
  	},
  	IIO_ENUM("powerdown_mode", IIO_SEPARATE, &ad5686_powerdown_mode_enum),
  	IIO_ENUM_AVAILABLE("powerdown_mode", &ad5686_powerdown_mode_enum),
  	{ },
  };
  
  #define AD5868_CHANNEL(chan, bits, _shift) {			\
  		.type = IIO_VOLTAGE,				\
  		.indexed = 1,					\
  		.output = 1,					\
  		.channel = chan,				\
  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
  		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\
  		.address = AD5686_ADDR_DAC(chan),		\
  		.scan_type = {					\
  			.sign = 'u',				\
  			.realbits = (bits),			\
  			.storagebits = 16,			\
  			.shift = (_shift),			\
  		},						\
  		.ext_info = ad5686_ext_info,			\
  }
  
  static const struct ad5686_chip_info ad5686_chip_info_tbl[] = {
  	[ID_AD5684] = {
  		.channel[0] = AD5868_CHANNEL(0, 12, 4),
  		.channel[1] = AD5868_CHANNEL(1, 12, 4),
  		.channel[2] = AD5868_CHANNEL(2, 12, 4),
  		.channel[3] = AD5868_CHANNEL(3, 12, 4),
  		.int_vref_mv = 2500,
  	},
  	[ID_AD5685] = {
  		.channel[0] = AD5868_CHANNEL(0, 14, 2),
  		.channel[1] = AD5868_CHANNEL(1, 14, 2),
  		.channel[2] = AD5868_CHANNEL(2, 14, 2),
  		.channel[3] = AD5868_CHANNEL(3, 14, 2),
  		.int_vref_mv = 2500,
  	},
  	[ID_AD5686] = {
  		.channel[0] = AD5868_CHANNEL(0, 16, 0),
  		.channel[1] = AD5868_CHANNEL(1, 16, 0),
  		.channel[2] = AD5868_CHANNEL(2, 16, 0),
  		.channel[3] = AD5868_CHANNEL(3, 16, 0),
  		.int_vref_mv = 2500,
  	},
  };
  
  
  static int ad5686_probe(struct spi_device *spi)
  {
  	struct ad5686_state *st;
  	struct iio_dev *indio_dev;
  	int ret, voltage_uv = 0;
  
  	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
  	if (indio_dev == NULL)
  		return  -ENOMEM;
  
  	st = iio_priv(indio_dev);
  	spi_set_drvdata(spi, indio_dev);
  
  	st->reg = devm_regulator_get_optional(&spi->dev, "vcc");
  	if (!IS_ERR(st->reg)) {
  		ret = regulator_enable(st->reg);
  		if (ret)
  			return ret;
  
  		ret = regulator_get_voltage(st->reg);
  		if (ret < 0)
  			goto error_disable_reg;
  
  		voltage_uv = ret;
  	}
  
  	st->chip_info =
  		&ad5686_chip_info_tbl[spi_get_device_id(spi)->driver_data];
  
  	if (voltage_uv)
  		st->vref_mv = voltage_uv / 1000;
  	else
  		st->vref_mv = st->chip_info->int_vref_mv;
  
  	st->spi = spi;
  
  	/* Set all the power down mode for all channels to 1K pulldown */
  	st->pwr_down_mode = 0x55;
  
  	indio_dev->dev.parent = &spi->dev;
  	indio_dev->name = spi_get_device_id(spi)->name;
  	indio_dev->info = &ad5686_info;
  	indio_dev->modes = INDIO_DIRECT_MODE;
  	indio_dev->channels = st->chip_info->channel;
  	indio_dev->num_channels = AD5686_DAC_CHANNELS;
  
  	ret = ad5686_spi_write(st, AD5686_CMD_INTERNAL_REFER_SETUP, 0,
  				!!voltage_uv, 0);
  	if (ret)
  		goto error_disable_reg;
  
  	ret = iio_device_register(indio_dev);
  	if (ret)
  		goto error_disable_reg;
  
  	return 0;
  
  error_disable_reg:
  	if (!IS_ERR(st->reg))
  		regulator_disable(st->reg);
  	return ret;
  }
  
  static int ad5686_remove(struct spi_device *spi)
  {
  	struct iio_dev *indio_dev = spi_get_drvdata(spi);
  	struct ad5686_state *st = iio_priv(indio_dev);
  
  	iio_device_unregister(indio_dev);
  	if (!IS_ERR(st->reg))
  		regulator_disable(st->reg);
  
  	return 0;
  }
  
  static const struct spi_device_id ad5686_id[] = {
  	{"ad5684", ID_AD5684},
  	{"ad5685", ID_AD5685},
  	{"ad5686", ID_AD5686},
  	{}
  };
  MODULE_DEVICE_TABLE(spi, ad5686_id);
  
  static struct spi_driver ad5686_driver = {
  	.driver = {
  		   .name = "ad5686",
  		   },
  	.probe = ad5686_probe,
  	.remove = ad5686_remove,
  	.id_table = ad5686_id,
  };
  module_spi_driver(ad5686_driver);
  
  MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
  MODULE_DESCRIPTION("Analog Devices AD5686/85/84 DAC");
  MODULE_LICENSE("GPL v2");
  