/*
 * AD7190 AD7192 AD7195 SPI ADC driver
 *
 * Copyright 2011 Analog Devices Inc.
 *
 * Licensed under the GPL-2.
 */

#include <linux/interrupt.h>
#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/sched.h>
#include <linux/delay.h>

#include "../iio.h"
#include "../sysfs.h"
#include "../buffer.h"
#include "../ring_sw.h"
#include "../trigger.h"
#include "../trigger_consumer.h"

#include "ad7192.h"

/* Registers */
#define AD7192_REG_COMM		0 /* Communications Register (WO, 8-bit) */
#define AD7192_REG_STAT		0 /* Status Register	     (RO, 8-bit) */
#define AD7192_REG_MODE		1 /* Mode Register	     (RW, 24-bit */
#define AD7192_REG_CONF		2 /* Configuration Register  (RW, 24-bit) */
#define AD7192_REG_DATA		3 /* Data Register	     (RO, 24/32-bit) */
#define AD7192_REG_ID		4 /* ID Register	     (RO, 8-bit) */
#define AD7192_REG_GPOCON	5 /* GPOCON Register	     (RO, 8-bit) */
#define AD7192_REG_OFFSET	6 /* Offset Register	     (RW, 16-bit
				   * (AD7792)/24-bit (AD7192)) */
#define AD7192_REG_FULLSALE	7 /* Full-Scale Register
				   * (RW, 16-bit (AD7792)/24-bit (AD7192)) */

/* Communications Register Bit Designations (AD7192_REG_COMM) */
#define AD7192_COMM_WEN		(1 << 7) /* Write Enable */
#define AD7192_COMM_WRITE	(0 << 6) /* Write Operation */
#define AD7192_COMM_READ	(1 << 6) /* Read Operation */
#define AD7192_COMM_ADDR(x)	(((x) & 0x7) << 3) /* Register Address */
#define AD7192_COMM_CREAD	(1 << 2) /* Continuous Read of Data Register */

/* Status Register Bit Designations (AD7192_REG_STAT) */
#define AD7192_STAT_RDY		(1 << 7) /* Ready */
#define AD7192_STAT_ERR		(1 << 6) /* Error (Overrange, Underrange) */
#define AD7192_STAT_NOREF	(1 << 5) /* Error no external reference */
#define AD7192_STAT_PARITY	(1 << 4) /* Parity */
#define AD7192_STAT_CH3		(1 << 2) /* Channel 3 */
#define AD7192_STAT_CH2		(1 << 1) /* Channel 2 */
#define AD7192_STAT_CH1		(1 << 0) /* Channel 1 */

/* Mode Register Bit Designations (AD7192_REG_MODE) */
#define AD7192_MODE_SEL(x)	(((x) & 0x7) << 21) /* Operation Mode Select */
#define AD7192_MODE_DAT_STA	(1 << 20) /* Status Register transmission */
#define AD7192_MODE_CLKSRC(x)	(((x) & 0x3) << 18) /* Clock Source Select */
#define AD7192_MODE_SINC3	(1 << 15) /* SINC3 Filter Select */
#define AD7192_MODE_ACX		(1 << 14) /* AC excitation enable(AD7195 only)*/
#define AD7192_MODE_ENPAR	(1 << 13) /* Parity Enable */
#define AD7192_MODE_CLKDIV	(1 << 12) /* Clock divide by 2 (AD7190/2 only)*/
#define AD7192_MODE_SCYCLE	(1 << 11) /* Single cycle conversion */
#define AD7192_MODE_REJ60	(1 << 10) /* 50/60Hz notch filter */
#define AD7192_MODE_RATE(x)	((x) & 0x3FF) /* Filter Update Rate Select */

/* Mode Register: AD7192_MODE_SEL options */
#define AD7192_MODE_CONT		0 /* Continuous Conversion Mode */
#define AD7192_MODE_SINGLE		1 /* Single Conversion Mode */
#define AD7192_MODE_IDLE		2 /* Idle Mode */
#define AD7192_MODE_PWRDN		3 /* Power-Down Mode */
#define AD7192_MODE_CAL_INT_ZERO	4 /* Internal Zero-Scale Calibration */
#define AD7192_MODE_CAL_INT_FULL	5 /* Internal Full-Scale Calibration */
#define AD7192_MODE_CAL_SYS_ZERO	6 /* System Zero-Scale Calibration */
#define AD7192_MODE_CAL_SYS_FULL	7 /* System Full-Scale Calibration */

/* Mode Register: AD7192_MODE_CLKSRC options */
#define AD7192_CLK_EXT_MCLK1_2		0 /* External 4.92 MHz Clock connected
					   * from MCLK1 to MCLK2 */
#define AD7192_CLK_EXT_MCLK2		1 /* External Clock applied to MCLK2 */
#define AD7192_CLK_INT			2 /* Internal 4.92 MHz Clock not
					   * available at the MCLK2 pin */
#define AD7192_CLK_INT_CO		3 /* Internal 4.92 MHz Clock available
					   * at the MCLK2 pin */


/* Configuration Register Bit Designations (AD7192_REG_CONF) */

#define AD7192_CONF_CHOP	(1 << 23) /* CHOP enable */
#define AD7192_CONF_REFSEL	(1 << 20) /* REFIN1/REFIN2 Reference Select */
#define AD7192_CONF_CHAN(x)	(((x) & 0xFF) << 8) /* Channel select */
#define AD7192_CONF_BURN	(1 << 7) /* Burnout current enable */
#define AD7192_CONF_REFDET	(1 << 6) /* Reference detect enable */
#define AD7192_CONF_BUF		(1 << 4) /* Buffered Mode Enable */
#define AD7192_CONF_UNIPOLAR	(1 << 3) /* Unipolar/Bipolar Enable */
#define AD7192_CONF_GAIN(x)	((x) & 0x7) /* Gain Select */

#define AD7192_CH_AIN1P_AIN2M	0 /* AIN1(+) - AIN2(-) */
#define AD7192_CH_AIN3P_AIN4M	1 /* AIN3(+) - AIN4(-) */
#define AD7192_CH_TEMP		2 /* Temp Sensor */
#define AD7192_CH_AIN2P_AIN2M	3 /* AIN2(+) - AIN2(-) */
#define AD7192_CH_AIN1		4 /* AIN1 - AINCOM */
#define AD7192_CH_AIN2		5 /* AIN2 - AINCOM */
#define AD7192_CH_AIN3		6 /* AIN3 - AINCOM */
#define AD7192_CH_AIN4		7 /* AIN4 - AINCOM */

/* ID Register Bit Designations (AD7192_REG_ID) */
#define ID_AD7190		0x4
#define ID_AD7192		0x0
#define ID_AD7195		0x6
#define AD7192_ID_MASK		0x0F

/* GPOCON Register Bit Designations (AD7192_REG_GPOCON) */
#define AD7192_GPOCON_BPDSW	(1 << 6) /* Bridge power-down switch enable */
#define AD7192_GPOCON_GP32EN	(1 << 5) /* Digital Output P3 and P2 enable */
#define AD7192_GPOCON_GP10EN	(1 << 4) /* Digital Output P1 and P0 enable */
#define AD7192_GPOCON_P3DAT	(1 << 3) /* P3 state */
#define AD7192_GPOCON_P2DAT	(1 << 2) /* P2 state */
#define AD7192_GPOCON_P1DAT	(1 << 1) /* P1 state */
#define AD7192_GPOCON_P0DAT	(1 << 0) /* P0 state */

#define AD7192_INT_FREQ_MHz	4915200

/* NOTE:
 * The AD7190/2/5 features a dual use data out ready DOUT/RDY output.
 * In order to avoid contentions on the SPI bus, it's therefore necessary
 * to use spi bus locking.
 *
 * The DOUT/RDY output must also be wired to an interrupt capable GPIO.
 */

struct ad7192_state {
	struct spi_device		*spi;
	struct iio_trigger		*trig;
	struct regulator		*reg;
	struct ad7192_platform_data	*pdata;
	wait_queue_head_t		wq_data_avail;
	bool				done;
	bool				irq_dis;
	u16				int_vref_mv;
	u32				mclk;
	u32				f_order;
	u32				mode;
	u32				conf;
	u32				scale_avail[8][2];
	long				available_scan_masks[9];
	u8				gpocon;
	u8				devid;
	/*
	 * DMA (thus cache coherency maintenance) requires the
	 * transfer buffers to live in their own cache lines.
	 */
	u8				data[4] ____cacheline_aligned;
};

static int __ad7192_write_reg(struct ad7192_state *st, bool locked,
			      bool cs_change, unsigned char reg,
			      unsigned size, unsigned val)
{
	u8 *data = st->data;
	struct spi_transfer t = {
		.tx_buf		= data,
		.len		= size + 1,
		.cs_change	= cs_change,
	};
	struct spi_message m;

	data[0] = AD7192_COMM_WRITE | AD7192_COMM_ADDR(reg);

	switch (size) {
	case 3:
		data[1] = val >> 16;
		data[2] = val >> 8;
		data[3] = val;
		break;
	case 2:
		data[1] = val >> 8;
		data[2] = val;
		break;
	case 1:
		data[1] = val;
		break;
	default:
		return -EINVAL;
	}

	spi_message_init(&m);
	spi_message_add_tail(&t, &m);

	if (locked)
		return spi_sync_locked(st->spi, &m);
	else
		return spi_sync(st->spi, &m);
}

static int ad7192_write_reg(struct ad7192_state *st,
			    unsigned reg, unsigned size, unsigned val)
{
	return __ad7192_write_reg(st, false, false, reg, size, val);
}

static int __ad7192_read_reg(struct ad7192_state *st, bool locked,
			     bool cs_change, unsigned char reg,
			     int *val, unsigned size)
{
	u8 *data = st->data;
	int ret;
	struct spi_transfer t[] = {
		{
			.tx_buf = data,
			.len = 1,
		}, {
			.rx_buf = data,
			.len = size,
			.cs_change = cs_change,
		},
	};
	struct spi_message m;

	data[0] = AD7192_COMM_READ | AD7192_COMM_ADDR(reg);

	spi_message_init(&m);
	spi_message_add_tail(&t[0], &m);
	spi_message_add_tail(&t[1], &m);

	if (locked)
		ret = spi_sync_locked(st->spi, &m);
	else
		ret = spi_sync(st->spi, &m);

	if (ret < 0)
		return ret;

	switch (size) {
	case 3:
		*val = data[0] << 16 | data[1] << 8 | data[2];
		break;
	case 2:
		*val = data[0] << 8 | data[1];
		break;
	case 1:
		*val = data[0];
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

static int ad7192_read_reg(struct ad7192_state *st,
			   unsigned reg, int *val, unsigned size)
{
	return __ad7192_read_reg(st, 0, 0, reg, val, size);
}

static int ad7192_read(struct ad7192_state *st, unsigned ch,
		       unsigned len, int *val)
{
	int ret;
	st->conf = (st->conf & ~AD7192_CONF_CHAN(-1)) |
		AD7192_CONF_CHAN(1 << ch);
	st->mode = (st->mode & ~AD7192_MODE_SEL(-1)) |
		AD7192_MODE_SEL(AD7192_MODE_SINGLE);

	ad7192_write_reg(st, AD7192_REG_CONF, 3, st->conf);

	spi_bus_lock(st->spi->master);
	st->done = false;

	ret = __ad7192_write_reg(st, 1, 1, AD7192_REG_MODE, 3, st->mode);
	if (ret < 0)
		goto out;

	st->irq_dis = false;
	enable_irq(st->spi->irq);
	wait_event_interruptible(st->wq_data_avail, st->done);

	ret = __ad7192_read_reg(st, 1, 0, AD7192_REG_DATA, val, len);
out:
	spi_bus_unlock(st->spi->master);

	return ret;
}

static int ad7192_calibrate(struct ad7192_state *st, unsigned mode, unsigned ch)
{
	int ret;

	st->conf = (st->conf & ~AD7192_CONF_CHAN(-1)) |
		AD7192_CONF_CHAN(1 << ch);
	st->mode = (st->mode & ~AD7192_MODE_SEL(-1)) | AD7192_MODE_SEL(mode);

	ad7192_write_reg(st, AD7192_REG_CONF, 3, st->conf);

	spi_bus_lock(st->spi->master);
	st->done = false;

	ret = __ad7192_write_reg(st, 1, 1, AD7192_REG_MODE, 3,
				 (st->devid != ID_AD7195) ?
				 st->mode | AD7192_MODE_CLKDIV :
				 st->mode);
	if (ret < 0)
		goto out;

	st->irq_dis = false;
	enable_irq(st->spi->irq);
	wait_event_interruptible(st->wq_data_avail, st->done);

	st->mode = (st->mode & ~AD7192_MODE_SEL(-1)) |
		AD7192_MODE_SEL(AD7192_MODE_IDLE);

	ret = __ad7192_write_reg(st, 1, 0, AD7192_REG_MODE, 3, st->mode);
out:
	spi_bus_unlock(st->spi->master);

	return ret;
}

static const u8 ad7192_calib_arr[8][2] = {
	{AD7192_MODE_CAL_INT_ZERO, AD7192_CH_AIN1},
	{AD7192_MODE_CAL_INT_FULL, AD7192_CH_AIN1},
	{AD7192_MODE_CAL_INT_ZERO, AD7192_CH_AIN2},
	{AD7192_MODE_CAL_INT_FULL, AD7192_CH_AIN2},
	{AD7192_MODE_CAL_INT_ZERO, AD7192_CH_AIN3},
	{AD7192_MODE_CAL_INT_FULL, AD7192_CH_AIN3},
	{AD7192_MODE_CAL_INT_ZERO, AD7192_CH_AIN4},
	{AD7192_MODE_CAL_INT_FULL, AD7192_CH_AIN4}
};

static int ad7192_calibrate_all(struct ad7192_state *st)
{
	int i, ret;

	for (i = 0; i < ARRAY_SIZE(ad7192_calib_arr); i++) {
		ret = ad7192_calibrate(st, ad7192_calib_arr[i][0],
				       ad7192_calib_arr[i][1]);
		if (ret)
			goto out;
	}

	return 0;
out:
	dev_err(&st->spi->dev, "Calibration failed\n");
	return ret;
}

static int ad7192_setup(struct ad7192_state *st)
{
	struct iio_dev *indio_dev = spi_get_drvdata(st->spi);
	struct ad7192_platform_data *pdata = st->pdata;
	unsigned long long scale_uv;
	int i, ret, id;
	u8 ones[6];

	/* reset the serial interface */
	memset(&ones, 0xFF, 6);
	ret = spi_write(st->spi, &ones, 6);
	if (ret < 0)
		goto out;
	msleep(1); /* Wait for at least 500us */

	/* write/read test for device presence */
	ret = ad7192_read_reg(st, AD7192_REG_ID, &id, 1);
	if (ret)
		goto out;

	id &= AD7192_ID_MASK;

	if (id != st->devid)
		dev_warn(&st->spi->dev, "device ID query failed (0x%X)\n", id);

	switch (pdata->clock_source_sel) {
	case AD7192_CLK_EXT_MCLK1_2:
	case AD7192_CLK_EXT_MCLK2:
		st->mclk = AD7192_INT_FREQ_MHz;
		break;
	case AD7192_CLK_INT:
	case AD7192_CLK_INT_CO:
		if (pdata->ext_clk_Hz)
			st->mclk = pdata->ext_clk_Hz;
		else
			st->mclk = AD7192_INT_FREQ_MHz;
			break;
	default:
		ret = -EINVAL;
		goto out;
	}

	st->mode = AD7192_MODE_SEL(AD7192_MODE_IDLE) |
		AD7192_MODE_CLKSRC(pdata->clock_source_sel) |
		AD7192_MODE_RATE(480);

	st->conf = AD7192_CONF_GAIN(0);

	if (pdata->rej60_en)
		st->mode |= AD7192_MODE_REJ60;

	if (pdata->sinc3_en)
		st->mode |= AD7192_MODE_SINC3;

	if (pdata->refin2_en && (st->devid != ID_AD7195))
		st->conf |= AD7192_CONF_REFSEL;

	if (pdata->chop_en) {
		st->conf |= AD7192_CONF_CHOP;
		if (pdata->sinc3_en)
			st->f_order = 3; /* SINC 3rd order */
		else
			st->f_order = 4; /* SINC 4th order */
	} else {
		st->f_order = 1;
	}

	if (pdata->buf_en)
		st->conf |= AD7192_CONF_BUF;

	if (pdata->unipolar_en)
		st->conf |= AD7192_CONF_UNIPOLAR;

	if (pdata->burnout_curr_en)
		st->conf |= AD7192_CONF_BURN;

	ret = ad7192_write_reg(st, AD7192_REG_MODE, 3, st->mode);
	if (ret)
		goto out;

	ret = ad7192_write_reg(st, AD7192_REG_CONF, 3, st->conf);
	if (ret)
		goto out;

	ret = ad7192_calibrate_all(st);
	if (ret)
		goto out;

	/* Populate available ADC input ranges */
	for (i = 0; i < ARRAY_SIZE(st->scale_avail); i++) {
		scale_uv = ((u64)st->int_vref_mv * 100000000)
			>> (indio_dev->channels[0].scan_type.realbits -
			((st->conf & AD7192_CONF_UNIPOLAR) ? 0 : 1));
		scale_uv >>= i;

		st->scale_avail[i][1] = do_div(scale_uv, 100000000) * 10;
		st->scale_avail[i][0] = scale_uv;
	}

	return 0;
out:
	dev_err(&st->spi->dev, "setup failed\n");
	return ret;
}

static int ad7192_ring_preenable(struct iio_dev *indio_dev)
{
	struct ad7192_state *st = iio_priv(indio_dev);
	struct iio_buffer *ring = indio_dev->buffer;
	size_t d_size;
	unsigned channel;

	if (bitmap_empty(indio_dev->active_scan_mask, indio_dev->masklength))
		return -EINVAL;

	channel = find_first_bit(indio_dev->active_scan_mask,
				 indio_dev->masklength);

	d_size = bitmap_weight(indio_dev->active_scan_mask,
			       indio_dev->masklength) *
		 indio_dev->channels[0].scan_type.storagebits / 8;

	if (ring->scan_timestamp) {
		d_size += sizeof(s64);

		if (d_size % sizeof(s64))
			d_size += sizeof(s64) - (d_size % sizeof(s64));
	}

	if (indio_dev->buffer->access->set_bytes_per_datum)
		indio_dev->buffer->access->
			set_bytes_per_datum(indio_dev->buffer, d_size);

	st->mode  = (st->mode & ~AD7192_MODE_SEL(-1)) |
		    AD7192_MODE_SEL(AD7192_MODE_CONT);
	st->conf  = (st->conf & ~AD7192_CONF_CHAN(-1)) |
		    AD7192_CONF_CHAN(1 << indio_dev->channels[channel].address);

	ad7192_write_reg(st, AD7192_REG_CONF, 3, st->conf);

	spi_bus_lock(st->spi->master);
	__ad7192_write_reg(st, 1, 1, AD7192_REG_MODE, 3, st->mode);

	st->irq_dis = false;
	enable_irq(st->spi->irq);

	return 0;
}

static int ad7192_ring_postdisable(struct iio_dev *indio_dev)
{
	struct ad7192_state *st = iio_priv(indio_dev);

	st->mode  = (st->mode & ~AD7192_MODE_SEL(-1)) |
		    AD7192_MODE_SEL(AD7192_MODE_IDLE);

	st->done = false;
	wait_event_interruptible(st->wq_data_avail, st->done);

	if (!st->irq_dis)
		disable_irq_nosync(st->spi->irq);

	__ad7192_write_reg(st, 1, 0, AD7192_REG_MODE, 3, st->mode);

	return spi_bus_unlock(st->spi->master);
}

/**
 * ad7192_trigger_handler() bh of trigger launched polling to ring buffer
 **/
static irqreturn_t ad7192_trigger_handler(int irq, void *p)
{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct iio_buffer *ring = indio_dev->buffer;
	struct ad7192_state *st = iio_priv(indio_dev);
	s64 dat64[2];
	s32 *dat32 = (s32 *)dat64;

	if (!bitmap_empty(indio_dev->active_scan_mask, indio_dev->masklength))
		__ad7192_read_reg(st, 1, 1, AD7192_REG_DATA,
				  dat32,
				  indio_dev->channels[0].scan_type.realbits/8);

	/* Guaranteed to be aligned with 8 byte boundary */
	if (ring->scan_timestamp)
		dat64[1] = pf->timestamp;

	ring->access->store_to(ring, (u8 *)dat64, pf->timestamp);

	iio_trigger_notify_done(indio_dev->trig);
	st->irq_dis = false;
	enable_irq(st->spi->irq);

	return IRQ_HANDLED;
}

static const struct iio_buffer_setup_ops ad7192_ring_setup_ops = {
	.preenable = &ad7192_ring_preenable,
	.postenable = &iio_triggered_buffer_postenable,
	.predisable = &iio_triggered_buffer_predisable,
	.postdisable = &ad7192_ring_postdisable,
};

static int ad7192_register_ring_funcs_and_init(struct iio_dev *indio_dev)
{
	int ret;

	indio_dev->buffer = iio_sw_rb_allocate(indio_dev);
	if (!indio_dev->buffer) {
		ret = -ENOMEM;
		goto error_ret;
	}
	/* Effectively select the ring buffer implementation */
	indio_dev->buffer->access = &ring_sw_access_funcs;
	indio_dev->pollfunc = iio_alloc_pollfunc(&iio_pollfunc_store_time,
						 &ad7192_trigger_handler,
						 IRQF_ONESHOT,
						 indio_dev,
						 "ad7192_consumer%d",
						 indio_dev->id);
	if (indio_dev->pollfunc == NULL) {
		ret = -ENOMEM;
		goto error_deallocate_sw_rb;
	}

	/* Ring buffer functions - here trigger setup related */
	indio_dev->setup_ops = &ad7192_ring_setup_ops;

	/* Flag that polled ring buffering is possible */
	indio_dev->modes |= INDIO_BUFFER_TRIGGERED;
	return 0;

error_deallocate_sw_rb:
	iio_sw_rb_free(indio_dev->buffer);
error_ret:
	return ret;
}

static void ad7192_ring_cleanup(struct iio_dev *indio_dev)
{
	iio_dealloc_pollfunc(indio_dev->pollfunc);
	iio_sw_rb_free(indio_dev->buffer);
}

/**
 * ad7192_data_rdy_trig_poll() the event handler for the data rdy trig
 **/
static irqreturn_t ad7192_data_rdy_trig_poll(int irq, void *private)
{
	struct ad7192_state *st = iio_priv(private);

	st->done = true;
	wake_up_interruptible(&st->wq_data_avail);
	disable_irq_nosync(irq);
	st->irq_dis = true;
	iio_trigger_poll(st->trig, iio_get_time_ns());

	return IRQ_HANDLED;
}

static struct iio_trigger_ops ad7192_trigger_ops = {
	.owner = THIS_MODULE,
};

static int ad7192_probe_trigger(struct iio_dev *indio_dev)
{
	struct ad7192_state *st = iio_priv(indio_dev);
	int ret;

	st->trig = iio_allocate_trigger("%s-dev%d",
					spi_get_device_id(st->spi)->name,
					indio_dev->id);
	if (st->trig == NULL) {
		ret = -ENOMEM;
		goto error_ret;
	}
	st->trig->ops = &ad7192_trigger_ops;
	ret = request_irq(st->spi->irq,
			  ad7192_data_rdy_trig_poll,
			  IRQF_TRIGGER_LOW,
			  spi_get_device_id(st->spi)->name,
			  indio_dev);
	if (ret)
		goto error_free_trig;

	disable_irq_nosync(st->spi->irq);
	st->irq_dis = true;
	st->trig->dev.parent = &st->spi->dev;
	st->trig->private_data = indio_dev;

	ret = iio_trigger_register(st->trig);

	/* select default trigger */
	indio_dev->trig = st->trig;
	if (ret)
		goto error_free_irq;

	return 0;

error_free_irq:
	free_irq(st->spi->irq, indio_dev);
error_free_trig:
	iio_free_trigger(st->trig);
error_ret:
	return ret;
}

static void ad7192_remove_trigger(struct iio_dev *indio_dev)
{
	struct ad7192_state *st = iio_priv(indio_dev);

	iio_trigger_unregister(st->trig);
	free_irq(st->spi->irq, indio_dev);
	iio_free_trigger(st->trig);
}

static ssize_t ad7192_read_frequency(struct device *dev,
		struct device_attribute *attr,
		char *buf)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct ad7192_state *st = iio_priv(indio_dev);

	return sprintf(buf, "%d\n", st->mclk /
			(st->f_order * 1024 * AD7192_MODE_RATE(st->mode)));
}

static ssize_t ad7192_write_frequency(struct device *dev,
		struct device_attribute *attr,
		const char *buf,
		size_t len)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct ad7192_state *st = iio_priv(indio_dev);
	unsigned long lval;
	int div, ret;

	ret = strict_strtoul(buf, 10, &lval);
	if (ret)
		return ret;

	mutex_lock(&indio_dev->mlock);
	if (iio_buffer_enabled(indio_dev)) {
		mutex_unlock(&indio_dev->mlock);
		return -EBUSY;
	}

	div = st->mclk / (lval * st->f_order * 1024);
	if (div < 1 || div > 1023) {
		ret = -EINVAL;
		goto out;
	}

	st->mode &= ~AD7192_MODE_RATE(-1);
	st->mode |= AD7192_MODE_RATE(div);
	ad7192_write_reg(st, AD7192_REG_MODE, 3, st->mode);

out:
	mutex_unlock(&indio_dev->mlock);

	return ret ? ret : len;
}

static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO,
		ad7192_read_frequency,
		ad7192_write_frequency);


static ssize_t ad7192_show_scale_available(struct device *dev,
			struct device_attribute *attr, char *buf)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct ad7192_state *st = iio_priv(indio_dev);
	int i, len = 0;

	for (i = 0; i < ARRAY_SIZE(st->scale_avail); i++)
		len += sprintf(buf + len, "%d.%09u ", st->scale_avail[i][0],
			       st->scale_avail[i][1]);

	len += sprintf(buf + len, "\n");

	return len;
}

static IIO_DEVICE_ATTR_NAMED(in_v_m_v_scale_available,
			     in_voltage-voltage_scale_available,
			     S_IRUGO, ad7192_show_scale_available, NULL, 0);

static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
		       ad7192_show_scale_available, NULL, 0);

static ssize_t ad7192_show_ac_excitation(struct device *dev,
		struct device_attribute *attr,
		char *buf)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct ad7192_state *st = iio_priv(indio_dev);

	return sprintf(buf, "%d\n", !!(st->mode & AD7192_MODE_ACX));
}

static ssize_t ad7192_show_bridge_switch(struct device *dev,
		struct device_attribute *attr,
		char *buf)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct ad7192_state *st = iio_priv(indio_dev);

	return sprintf(buf, "%d\n", !!(st->gpocon & AD7192_GPOCON_BPDSW));
}

static ssize_t ad7192_set(struct device *dev,
		struct device_attribute *attr,
		const char *buf,
		size_t len)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct ad7192_state *st = iio_priv(indio_dev);
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
	int ret;
	bool val;

	ret = strtobool(buf, &val);
	if (ret < 0)
		return ret;

	mutex_lock(&indio_dev->mlock);
	if (iio_buffer_enabled(indio_dev)) {
		mutex_unlock(&indio_dev->mlock);
		return -EBUSY;
	}

	switch ((u32) this_attr->address) {
	case AD7192_REG_GPOCON:
		if (val)
			st->gpocon |= AD7192_GPOCON_BPDSW;
		else
			st->gpocon &= ~AD7192_GPOCON_BPDSW;

		ad7192_write_reg(st, AD7192_REG_GPOCON, 1, st->gpocon);
		break;
	case AD7192_REG_MODE:
		if (val)
			st->mode |= AD7192_MODE_ACX;
		else
			st->mode &= ~AD7192_MODE_ACX;

		ad7192_write_reg(st, AD7192_REG_GPOCON, 3, st->mode);
		break;
	default:
		ret = -EINVAL;
	}

	mutex_unlock(&indio_dev->mlock);

	return ret ? ret : len;
}

static IIO_DEVICE_ATTR(bridge_switch_en, S_IRUGO | S_IWUSR,
		       ad7192_show_bridge_switch, ad7192_set,
		       AD7192_REG_GPOCON);

static IIO_DEVICE_ATTR(ac_excitation_en, S_IRUGO | S_IWUSR,
		       ad7192_show_ac_excitation, ad7192_set,
		       AD7192_REG_MODE);

static struct attribute *ad7192_attributes[] = {
	&iio_dev_attr_sampling_frequency.dev_attr.attr,
	&iio_dev_attr_in_v_m_v_scale_available.dev_attr.attr,
	&iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
	&iio_dev_attr_bridge_switch_en.dev_attr.attr,
	&iio_dev_attr_ac_excitation_en.dev_attr.attr,
	NULL
};

static umode_t ad7192_attr_is_visible(struct kobject *kobj,
				     struct attribute *attr, int n)
{
	struct device *dev = container_of(kobj, struct device, kobj);
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct ad7192_state *st = iio_priv(indio_dev);

	umode_t mode = attr->mode;

	if ((st->devid != ID_AD7195) &&
		(attr == &iio_dev_attr_ac_excitation_en.dev_attr.attr))
		mode = 0;

	return mode;
}

static const struct attribute_group ad7192_attribute_group = {
	.attrs = ad7192_attributes,
	.is_visible = ad7192_attr_is_visible,
};

static int ad7192_read_raw(struct iio_dev *indio_dev,
			   struct iio_chan_spec const *chan,
			   int *val,
			   int *val2,
			   long m)
{
	struct ad7192_state *st = iio_priv(indio_dev);
	int ret, smpl = 0;
	bool unipolar = !!(st->conf & AD7192_CONF_UNIPOLAR);

	switch (m) {
	case 0:
		mutex_lock(&indio_dev->mlock);
		if (iio_buffer_enabled(indio_dev))
			ret = -EBUSY;
		else
			ret = ad7192_read(st, chan->address,
					chan->scan_type.realbits / 8, &smpl);
		mutex_unlock(&indio_dev->mlock);

		if (ret < 0)
			return ret;

		*val = (smpl >> chan->scan_type.shift) &
			((1 << (chan->scan_type.realbits)) - 1);

		switch (chan->type) {
		case IIO_VOLTAGE:
			if (!unipolar)
				*val -= (1 << (chan->scan_type.realbits - 1));
			break;
		case IIO_TEMP:
			*val -= 0x800000;
			*val /= 2815; /* temp Kelvin */
			*val -= 273; /* temp Celsius */
			break;
		default:
			return -EINVAL;
		}
		return IIO_VAL_INT;

	case IIO_CHAN_INFO_SCALE:
		switch (chan->type) {
		case IIO_VOLTAGE:
			mutex_lock(&indio_dev->mlock);
			*val = st->scale_avail[AD7192_CONF_GAIN(st->conf)][0];
			*val2 = st->scale_avail[AD7192_CONF_GAIN(st->conf)][1];
			mutex_unlock(&indio_dev->mlock);
			return IIO_VAL_INT_PLUS_NANO;
		case IIO_TEMP:
			*val =  1000;
			return IIO_VAL_INT;
		default:
			return -EINVAL;
		}
	}

	return -EINVAL;
}

static int ad7192_write_raw(struct iio_dev *indio_dev,
			       struct iio_chan_spec const *chan,
			       int val,
			       int val2,
			       long mask)
{
	struct ad7192_state *st = iio_priv(indio_dev);
	int ret, i;
	unsigned int tmp;

	mutex_lock(&indio_dev->mlock);
	if (iio_buffer_enabled(indio_dev)) {
		mutex_unlock(&indio_dev->mlock);
		return -EBUSY;
	}

	switch (mask) {
	case IIO_CHAN_INFO_SCALE:
		ret = -EINVAL;
		for (i = 0; i < ARRAY_SIZE(st->scale_avail); i++)
			if (val2 == st->scale_avail[i][1]) {
				tmp = st->conf;
				st->conf &= ~AD7192_CONF_GAIN(-1);
				st->conf |= AD7192_CONF_GAIN(i);

				if (tmp != st->conf) {
					ad7192_write_reg(st, AD7192_REG_CONF,
							 3, st->conf);
					ad7192_calibrate_all(st);
				}
				ret = 0;
			}

	default:
		ret = -EINVAL;
	}

	mutex_unlock(&indio_dev->mlock);

	return ret;
}

static int ad7192_validate_trigger(struct iio_dev *indio_dev,
				   struct iio_trigger *trig)
{
	if (indio_dev->trig != trig)
		return -EINVAL;

	return 0;
}

static int ad7192_write_raw_get_fmt(struct iio_dev *indio_dev,
			       struct iio_chan_spec const *chan,
			       long mask)
{
	return IIO_VAL_INT_PLUS_NANO;
}

static const struct iio_info ad7192_info = {
	.read_raw = &ad7192_read_raw,
	.write_raw = &ad7192_write_raw,
	.write_raw_get_fmt = &ad7192_write_raw_get_fmt,
	.attrs = &ad7192_attribute_group,
	.validate_trigger = ad7192_validate_trigger,
	.driver_module = THIS_MODULE,
};

#define AD7192_CHAN_DIFF(_chan, _chan2, _name, _address, _si)		\
	{ .type = IIO_VOLTAGE,						\
	  .differential = 1,						\
	  .indexed = 1,							\
	  .extend_name = _name,						\
	  .channel = _chan,						\
	  .channel2 = _chan2,						\
	  .info_mask = IIO_CHAN_INFO_SCALE_SHARED_BIT,		\
	  .address = _address,						\
	  .scan_index = _si,						\
	  .scan_type =  IIO_ST('s', 24, 32, 0)}

#define AD7192_CHAN(_chan, _address, _si)				\
	{ .type = IIO_VOLTAGE,						\
	  .indexed = 1,							\
	  .channel = _chan,						\
	  .info_mask = IIO_CHAN_INFO_SCALE_SHARED_BIT,		\
	  .address = _address,						\
	  .scan_index = _si,						\
	  .scan_type =  IIO_ST('s', 24, 32, 0)}

#define AD7192_CHAN_TEMP(_chan, _address, _si)				\
	{ .type = IIO_TEMP,						\
	  .indexed = 1,							\
	  .channel = _chan,						\
	  .info_mask = IIO_CHAN_INFO_SCALE_SEPARATE_BIT,		\
	  .address = _address,						\
	  .scan_index = _si,						\
	  .scan_type =  IIO_ST('s', 24, 32, 0)}

static struct iio_chan_spec ad7192_channels[] = {
	AD7192_CHAN_DIFF(1, 2, NULL, AD7192_CH_AIN1P_AIN2M, 0),
	AD7192_CHAN_DIFF(3, 4, NULL, AD7192_CH_AIN3P_AIN4M, 1),
	AD7192_CHAN_TEMP(0, AD7192_CH_TEMP, 2),
	AD7192_CHAN_DIFF(2, 2, "shorted", AD7192_CH_AIN2P_AIN2M, 3),
	AD7192_CHAN(1, AD7192_CH_AIN1, 4),
	AD7192_CHAN(2, AD7192_CH_AIN2, 5),
	AD7192_CHAN(3, AD7192_CH_AIN3, 6),
	AD7192_CHAN(4, AD7192_CH_AIN4, 7),
	IIO_CHAN_SOFT_TIMESTAMP(8),
};

static int __devinit ad7192_probe(struct spi_device *spi)
{
	struct ad7192_platform_data *pdata = spi->dev.platform_data;
	struct ad7192_state *st;
	struct iio_dev *indio_dev;
	int ret, i , voltage_uv = 0;

	if (!pdata) {
		dev_err(&spi->dev, "no platform data?\n");
		return -ENODEV;
	}

	if (!spi->irq) {
		dev_err(&spi->dev, "no IRQ?\n");
		return -ENODEV;
	}

	indio_dev = iio_allocate_device(sizeof(*st));
	if (indio_dev == NULL)
		return -ENOMEM;

	st = iio_priv(indio_dev);

	st->reg = regulator_get(&spi->dev, "vcc");
	if (!IS_ERR(st->reg)) {
		ret = regulator_enable(st->reg);
		if (ret)
			goto error_put_reg;

		voltage_uv = regulator_get_voltage(st->reg);
	}

	st->pdata = pdata;

	if (pdata && pdata->vref_mv)
		st->int_vref_mv = pdata->vref_mv;
	else if (voltage_uv)
		st->int_vref_mv = voltage_uv / 1000;
	else
		dev_warn(&spi->dev, "reference voltage undefined\n");

	spi_set_drvdata(spi, indio_dev);
	st->spi = spi;
	st->devid = spi_get_device_id(spi)->driver_data;
	indio_dev->dev.parent = &spi->dev;
	indio_dev->name = spi_get_device_id(spi)->name;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = ad7192_channels;
	indio_dev->num_channels = ARRAY_SIZE(ad7192_channels);
	indio_dev->available_scan_masks = st->available_scan_masks;
	indio_dev->info = &ad7192_info;

	for (i = 0; i < indio_dev->num_channels; i++)
		st->available_scan_masks[i] = (1 << i) | (1 <<
			indio_dev->channels[indio_dev->num_channels - 1].
			scan_index);

	init_waitqueue_head(&st->wq_data_avail);

	ret = ad7192_register_ring_funcs_and_init(indio_dev);
	if (ret)
		goto error_disable_reg;

	ret = ad7192_probe_trigger(indio_dev);
	if (ret)
		goto error_ring_cleanup;

	ret = iio_buffer_register(indio_dev,
				  indio_dev->channels,
				  indio_dev->num_channels);
	if (ret)
		goto error_remove_trigger;

	ret = ad7192_setup(st);
	if (ret)
		goto error_unreg_ring;

	ret = iio_device_register(indio_dev);
	if (ret < 0)
		goto error_unreg_ring;
	return 0;

error_unreg_ring:
	iio_buffer_unregister(indio_dev);
error_remove_trigger:
	ad7192_remove_trigger(indio_dev);
error_ring_cleanup:
	ad7192_ring_cleanup(indio_dev);
error_disable_reg:
	if (!IS_ERR(st->reg))
		regulator_disable(st->reg);
error_put_reg:
	if (!IS_ERR(st->reg))
		regulator_put(st->reg);

	iio_free_device(indio_dev);

	return ret;
}

static int ad7192_remove(struct spi_device *spi)
{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);
	struct ad7192_state *st = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);
	iio_buffer_unregister(indio_dev);
	ad7192_remove_trigger(indio_dev);
	ad7192_ring_cleanup(indio_dev);

	if (!IS_ERR(st->reg)) {
		regulator_disable(st->reg);
		regulator_put(st->reg);
	}

	return 0;
}

static const struct spi_device_id ad7192_id[] = {
	{"ad7190", ID_AD7190},
	{"ad7192", ID_AD7192},
	{"ad7195", ID_AD7195},
	{}
};
MODULE_DEVICE_TABLE(spi, ad7192_id);

static struct spi_driver ad7192_driver = {
	.driver = {
		.name	= "ad7192",
		.owner	= THIS_MODULE,
	},
	.probe		= ad7192_probe,
	.remove		= __devexit_p(ad7192_remove),
	.id_table	= ad7192_id,
};
module_spi_driver(ad7192_driver);

MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
MODULE_DESCRIPTION("Analog Devices AD7190, AD7192, AD7195 ADC");
MODULE_LICENSE("GPL v2");