/*
 * ad2s1210.c support for the ADI Resolver to Digital Converters: AD2S1210
 *
 * Copyright (c) 2010-2010 Analog Devices Inc.
 *
 * 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/types.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/spi/spi.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/delay.h>
#include <linux/gpio.h>
#include <linux/module.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include "ad2s1210.h"

#define DRV_NAME "ad2s1210"

#define AD2S1210_DEF_CONTROL		0x7E

#define AD2S1210_MSB_IS_HIGH		0x80
#define AD2S1210_MSB_IS_LOW		0x7F
#define AD2S1210_PHASE_LOCK_RANGE_44	0x20
#define AD2S1210_ENABLE_HYSTERESIS	0x10
#define AD2S1210_SET_ENRES1		0x08
#define AD2S1210_SET_ENRES0		0x04
#define AD2S1210_SET_RES1		0x02
#define AD2S1210_SET_RES0		0x01

#define AD2S1210_SET_ENRESOLUTION	(AD2S1210_SET_ENRES1 |	\
					 AD2S1210_SET_ENRES0)
#define AD2S1210_SET_RESOLUTION		(AD2S1210_SET_RES1 | AD2S1210_SET_RES0)

#define AD2S1210_REG_POSITION		0x80
#define AD2S1210_REG_VELOCITY		0x82
#define AD2S1210_REG_LOS_THRD		0x88
#define AD2S1210_REG_DOS_OVR_THRD	0x89
#define AD2S1210_REG_DOS_MIS_THRD	0x8A
#define AD2S1210_REG_DOS_RST_MAX_THRD	0x8B
#define AD2S1210_REG_DOS_RST_MIN_THRD	0x8C
#define AD2S1210_REG_LOT_HIGH_THRD	0x8D
#define AD2S1210_REG_LOT_LOW_THRD	0x8E
#define AD2S1210_REG_EXCIT_FREQ		0x91
#define AD2S1210_REG_CONTROL		0x92
#define AD2S1210_REG_SOFT_RESET		0xF0
#define AD2S1210_REG_FAULT		0xFF

/* pin SAMPLE, A0, A1, RES0, RES1, is controlled by driver */
#define AD2S1210_SAA		3
#define AD2S1210_PN		(AD2S1210_SAA + AD2S1210_RES)

#define AD2S1210_MIN_CLKIN	6144000
#define AD2S1210_MAX_CLKIN	10240000
#define AD2S1210_MIN_EXCIT	2000
#define AD2S1210_MAX_EXCIT	20000
#define AD2S1210_MIN_FCW	0x4
#define AD2S1210_MAX_FCW	0x50

/* default input clock on serial interface */
#define AD2S1210_DEF_CLKIN	8192000
/* clock period in nano second */
#define AD2S1210_DEF_TCK	(1000000000/AD2S1210_DEF_CLKIN)
#define AD2S1210_DEF_EXCIT	10000

enum ad2s1210_mode {
	MOD_POS = 0,
	MOD_VEL,
	MOD_CONFIG,
	MOD_RESERVED,
};

static const unsigned int ad2s1210_resolution_value[] = { 10, 12, 14, 16 };

struct ad2s1210_state {
	const struct ad2s1210_platform_data *pdata;
	struct mutex lock;
	struct spi_device *sdev;
	unsigned int fclkin;
	unsigned int fexcit;
	bool hysteresis;
	bool old_data;
	u8 resolution;
	enum ad2s1210_mode mode;
	u8 rx[2] ____cacheline_aligned;
	u8 tx[2] ____cacheline_aligned;
};

static const int ad2s1210_mode_vals[4][2] = {
	[MOD_POS] = { 0, 0 },
	[MOD_VEL] = { 0, 1 },
	[MOD_CONFIG] = { 1, 0 },
};
static inline void ad2s1210_set_mode(enum ad2s1210_mode mode,
				     struct ad2s1210_state *st)
{
	gpio_set_value(st->pdata->a[0], ad2s1210_mode_vals[mode][0]);
	gpio_set_value(st->pdata->a[1], ad2s1210_mode_vals[mode][1]);
	st->mode = mode;
}

/* write 1 bytes (address or data) to the chip */
static int ad2s1210_config_write(struct ad2s1210_state *st, u8 data)
{
	int ret;

	ad2s1210_set_mode(MOD_CONFIG, st);
	st->tx[0] = data;
	ret = spi_write(st->sdev, st->tx, 1);
	if (ret < 0)
		return ret;
	st->old_data = true;

	return 0;
}

/* read value from one of the registers */
static int ad2s1210_config_read(struct ad2s1210_state *st,
		       unsigned char address)
{
	struct spi_transfer xfer = {
		.len = 2,
		.rx_buf = st->rx,
		.tx_buf = st->tx,
	};
	int ret = 0;

	ad2s1210_set_mode(MOD_CONFIG, st);
	st->tx[0] = address | AD2S1210_MSB_IS_HIGH;
	st->tx[1] = AD2S1210_REG_FAULT;
	ret = spi_sync_transfer(st->sdev, &xfer, 1);
	if (ret < 0)
		return ret;
	st->old_data = true;

	return st->rx[1];
}

static inline
int ad2s1210_update_frequency_control_word(struct ad2s1210_state *st)
{
	int ret;
	unsigned char fcw;

	fcw = (unsigned char)(st->fexcit * (1 << 15) / st->fclkin);
	if (fcw < AD2S1210_MIN_FCW || fcw > AD2S1210_MAX_FCW) {
		pr_err("ad2s1210: FCW out of range\n");
		return -ERANGE;
	}

	ret = ad2s1210_config_write(st, AD2S1210_REG_EXCIT_FREQ);
	if (ret < 0)
		return ret;

	return ad2s1210_config_write(st, fcw);
}

static unsigned char ad2s1210_read_resolution_pin(struct ad2s1210_state *st)
{
	return ad2s1210_resolution_value[
		(gpio_get_value(st->pdata->res[0]) << 1) |
		gpio_get_value(st->pdata->res[1])];
}

static const int ad2s1210_res_pins[4][2] = {
	{ 0, 0 }, {0, 1}, {1, 0}, {1, 1}
};

static inline void ad2s1210_set_resolution_pin(struct ad2s1210_state *st)
{
	gpio_set_value(st->pdata->res[0],
		       ad2s1210_res_pins[(st->resolution - 10)/2][0]);
	gpio_set_value(st->pdata->res[1],
		       ad2s1210_res_pins[(st->resolution - 10)/2][1]);
}

static inline int ad2s1210_soft_reset(struct ad2s1210_state *st)
{
	int ret;

	ret = ad2s1210_config_write(st, AD2S1210_REG_SOFT_RESET);
	if (ret < 0)
		return ret;

	return ad2s1210_config_write(st, 0x0);
}

static ssize_t ad2s1210_store_softreset(struct device *dev,
					struct device_attribute *attr,
					const char *buf,
					size_t len)
{
	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
	int ret;

	mutex_lock(&st->lock);
	ret = ad2s1210_soft_reset(st);
	mutex_unlock(&st->lock);

	return ret < 0 ? ret : len;
}

static ssize_t ad2s1210_show_fclkin(struct device *dev,
				    struct device_attribute *attr,
				    char *buf)
{
	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
	return sprintf(buf, "%d\n", st->fclkin);
}

static ssize_t ad2s1210_store_fclkin(struct device *dev,
				     struct device_attribute *attr,
				     const char *buf,
				     size_t len)
{
	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
	unsigned long fclkin;
	int ret;

	ret = strict_strtoul(buf, 10, &fclkin);
	if (ret)
		return ret;
	if (fclkin < AD2S1210_MIN_CLKIN || fclkin > AD2S1210_MAX_CLKIN) {
		pr_err("ad2s1210: fclkin out of range\n");
		return -EINVAL;
	}

	mutex_lock(&st->lock);
	st->fclkin = fclkin;

	ret = ad2s1210_update_frequency_control_word(st);
	if (ret < 0)
		goto error_ret;
	ret = ad2s1210_soft_reset(st);
error_ret:
	mutex_unlock(&st->lock);

	return ret < 0 ? ret : len;
}

static ssize_t ad2s1210_show_fexcit(struct device *dev,
				    struct device_attribute *attr,
				    char *buf)
{
	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
	return sprintf(buf, "%d\n", st->fexcit);
}

static ssize_t ad2s1210_store_fexcit(struct device *dev,
				     struct device_attribute *attr,
				     const char *buf, size_t len)
{
	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
	unsigned long fexcit;
	int ret;

	ret = strict_strtoul(buf, 10, &fexcit);
	if (ret < 0)
		return ret;
	if (fexcit < AD2S1210_MIN_EXCIT || fexcit > AD2S1210_MAX_EXCIT) {
		pr_err("ad2s1210: excitation frequency out of range\n");
		return -EINVAL;
	}
	mutex_lock(&st->lock);
	st->fexcit = fexcit;
	ret = ad2s1210_update_frequency_control_word(st);
	if (ret < 0)
		goto error_ret;
	ret = ad2s1210_soft_reset(st);
error_ret:
	mutex_unlock(&st->lock);

	return ret < 0 ? ret : len;
}

static ssize_t ad2s1210_show_control(struct device *dev,
				     struct device_attribute *attr,
				     char *buf)
{
	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
	int ret;
	mutex_lock(&st->lock);
	ret = ad2s1210_config_read(st, AD2S1210_REG_CONTROL);
	mutex_unlock(&st->lock);
	return ret < 0 ? ret : sprintf(buf, "0x%x\n", ret);
}

static ssize_t ad2s1210_store_control(struct device *dev,
			struct device_attribute *attr,
			const char *buf, size_t len)
{
	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
	unsigned long udata;
	unsigned char data;
	int ret;

	ret = strict_strtoul(buf, 16, &udata);
	if (ret)
		return -EINVAL;

	mutex_lock(&st->lock);
	ret = ad2s1210_config_write(st, AD2S1210_REG_CONTROL);
	if (ret < 0)
		goto error_ret;
	data = udata & AD2S1210_MSB_IS_LOW;
	ret = ad2s1210_config_write(st, data);
	if (ret < 0)
		goto error_ret;

	ret = ad2s1210_config_read(st, AD2S1210_REG_CONTROL);
	if (ret < 0)
		goto error_ret;
	if (ret & AD2S1210_MSB_IS_HIGH) {
		ret = -EIO;
		pr_err("ad2s1210: write control register fail\n");
		goto error_ret;
	}
	st->resolution
		= ad2s1210_resolution_value[data & AD2S1210_SET_RESOLUTION];
	if (st->pdata->gpioin) {
		data = ad2s1210_read_resolution_pin(st);
		if (data != st->resolution)
			pr_warning("ad2s1210: resolution settings not match\n");
	} else
		ad2s1210_set_resolution_pin(st);

	ret = len;
	st->hysteresis = !!(data & AD2S1210_ENABLE_HYSTERESIS);

error_ret:
	mutex_unlock(&st->lock);
	return ret;
}

static ssize_t ad2s1210_show_resolution(struct device *dev,
			struct device_attribute *attr, char *buf)
{
	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
	return sprintf(buf, "%d\n", st->resolution);
}

static ssize_t ad2s1210_store_resolution(struct device *dev,
			struct device_attribute *attr,
			const char *buf, size_t len)
{
	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
	unsigned char data;
	unsigned long udata;
	int ret;

	ret = strict_strtoul(buf, 10, &udata);
	if (ret || udata < 10 || udata > 16) {
		pr_err("ad2s1210: resolution out of range\n");
		return -EINVAL;
	}
	mutex_lock(&st->lock);
	ret = ad2s1210_config_read(st, AD2S1210_REG_CONTROL);
	if (ret < 0)
		goto error_ret;
	data = ret;
	data &= ~AD2S1210_SET_RESOLUTION;
	data |= (udata - 10) >> 1;
	ret = ad2s1210_config_write(st, AD2S1210_REG_CONTROL);
	if (ret < 0)
		goto error_ret;
	ret = ad2s1210_config_write(st, data & AD2S1210_MSB_IS_LOW);
	if (ret < 0)
		goto error_ret;
	ret = ad2s1210_config_read(st, AD2S1210_REG_CONTROL);
	if (ret < 0)
		goto error_ret;
	data = ret;
	if (data & AD2S1210_MSB_IS_HIGH) {
		ret = -EIO;
		pr_err("ad2s1210: setting resolution fail\n");
		goto error_ret;
	}
	st->resolution
		= ad2s1210_resolution_value[data & AD2S1210_SET_RESOLUTION];
	if (st->pdata->gpioin) {
		data = ad2s1210_read_resolution_pin(st);
		if (data != st->resolution)
			pr_warning("ad2s1210: resolution settings not match\n");
	} else
		ad2s1210_set_resolution_pin(st);
	ret = len;
error_ret:
	mutex_unlock(&st->lock);
	return ret;
}

/* read the fault register since last sample */
static ssize_t ad2s1210_show_fault(struct device *dev,
			struct device_attribute *attr, char *buf)
{
	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
	int ret;

	mutex_lock(&st->lock);
	ret = ad2s1210_config_read(st, AD2S1210_REG_FAULT);
	mutex_unlock(&st->lock);

	return ret ? ret : sprintf(buf, "0x%x\n", ret);
}

static ssize_t ad2s1210_clear_fault(struct device *dev,
				    struct device_attribute *attr,
				    const char *buf,
				    size_t len)
{
	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
	int ret;

	mutex_lock(&st->lock);
	gpio_set_value(st->pdata->sample, 0);
	/* delay (2 * tck + 20) nano seconds */
	udelay(1);
	gpio_set_value(st->pdata->sample, 1);
	ret = ad2s1210_config_read(st, AD2S1210_REG_FAULT);
	if (ret < 0)
		goto error_ret;
	gpio_set_value(st->pdata->sample, 0);
	gpio_set_value(st->pdata->sample, 1);
error_ret:
	mutex_unlock(&st->lock);

	return ret < 0 ? ret : len;
}

static ssize_t ad2s1210_show_reg(struct device *dev,
				 struct device_attribute *attr,
				 char *buf)
{
	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
	struct iio_dev_attr *iattr = to_iio_dev_attr(attr);
	int ret;

	mutex_lock(&st->lock);
	ret = ad2s1210_config_read(st, iattr->address);
	mutex_unlock(&st->lock);

	return ret < 0 ? ret : sprintf(buf, "%d\n", ret);
}

static ssize_t ad2s1210_store_reg(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t len)
{
	struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
	unsigned long data;
	int ret;
	struct iio_dev_attr *iattr = to_iio_dev_attr(attr);

	ret = strict_strtoul(buf, 10, &data);
	if (ret)
		return -EINVAL;
	mutex_lock(&st->lock);
	ret = ad2s1210_config_write(st, iattr->address);
	if (ret < 0)
		goto error_ret;
	ret = ad2s1210_config_write(st, data & AD2S1210_MSB_IS_LOW);
error_ret:
	mutex_unlock(&st->lock);
	return ret < 0 ? ret : len;
}

static int ad2s1210_read_raw(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan,
			     int *val,
			     int *val2,
			     long m)
{
	struct ad2s1210_state *st = iio_priv(indio_dev);
	bool negative;
	int ret = 0;
	u16 pos;
	s16 vel;

	mutex_lock(&st->lock);
	gpio_set_value(st->pdata->sample, 0);
	/* delay (6 * tck + 20) nano seconds */
	udelay(1);

	switch (chan->type) {
	case IIO_ANGL:
		ad2s1210_set_mode(MOD_POS, st);
		break;
	case IIO_ANGL_VEL:
		ad2s1210_set_mode(MOD_VEL, st);
		break;
	default:
	       ret = -EINVAL;
	       break;
	}
	if (ret < 0)
		goto error_ret;
	ret = spi_read(st->sdev, st->rx, 2);
	if (ret < 0)
		goto error_ret;

	switch (chan->type) {
	case IIO_ANGL:
		pos = be16_to_cpup((u16 *)st->rx);
		if (st->hysteresis)
			pos >>= 16 - st->resolution;
		*val = pos;
		ret = IIO_VAL_INT;
		break;
	case IIO_ANGL_VEL:
		negative = st->rx[0] & 0x80;
		vel = be16_to_cpup((s16 *)st->rx);
		vel >>= 16 - st->resolution;
		if (vel & 0x8000) {
			negative = (0xffff >> st->resolution) << st->resolution;
			vel |= negative;
		}
		*val = vel;
		ret = IIO_VAL_INT;
		break;
	default:
		mutex_unlock(&st->lock);
		return -EINVAL;
	}

error_ret:
	gpio_set_value(st->pdata->sample, 1);
	/* delay (2 * tck + 20) nano seconds */
	udelay(1);
	mutex_unlock(&st->lock);
	return ret;
}

static IIO_DEVICE_ATTR(reset, S_IWUSR,
		       NULL, ad2s1210_store_softreset, 0);
static IIO_DEVICE_ATTR(fclkin, S_IRUGO | S_IWUSR,
		       ad2s1210_show_fclkin, ad2s1210_store_fclkin, 0);
static IIO_DEVICE_ATTR(fexcit, S_IRUGO | S_IWUSR,
		       ad2s1210_show_fexcit,	ad2s1210_store_fexcit, 0);
static IIO_DEVICE_ATTR(control, S_IRUGO | S_IWUSR,
		       ad2s1210_show_control, ad2s1210_store_control, 0);
static IIO_DEVICE_ATTR(bits, S_IRUGO | S_IWUSR,
		       ad2s1210_show_resolution, ad2s1210_store_resolution, 0);
static IIO_DEVICE_ATTR(fault, S_IRUGO | S_IWUSR,
		       ad2s1210_show_fault, ad2s1210_clear_fault, 0);

static IIO_DEVICE_ATTR(los_thrd, S_IRUGO | S_IWUSR,
		       ad2s1210_show_reg, ad2s1210_store_reg,
		       AD2S1210_REG_LOS_THRD);
static IIO_DEVICE_ATTR(dos_ovr_thrd, S_IRUGO | S_IWUSR,
		       ad2s1210_show_reg, ad2s1210_store_reg,
		       AD2S1210_REG_DOS_OVR_THRD);
static IIO_DEVICE_ATTR(dos_mis_thrd, S_IRUGO | S_IWUSR,
		       ad2s1210_show_reg, ad2s1210_store_reg,
		       AD2S1210_REG_DOS_MIS_THRD);
static IIO_DEVICE_ATTR(dos_rst_max_thrd, S_IRUGO | S_IWUSR,
		       ad2s1210_show_reg, ad2s1210_store_reg,
		       AD2S1210_REG_DOS_RST_MAX_THRD);
static IIO_DEVICE_ATTR(dos_rst_min_thrd, S_IRUGO | S_IWUSR,
		       ad2s1210_show_reg, ad2s1210_store_reg,
		       AD2S1210_REG_DOS_RST_MIN_THRD);
static IIO_DEVICE_ATTR(lot_high_thrd, S_IRUGO | S_IWUSR,
		       ad2s1210_show_reg, ad2s1210_store_reg,
		       AD2S1210_REG_LOT_HIGH_THRD);
static IIO_DEVICE_ATTR(lot_low_thrd, S_IRUGO | S_IWUSR,
		       ad2s1210_show_reg, ad2s1210_store_reg,
		       AD2S1210_REG_LOT_LOW_THRD);


static const struct iio_chan_spec ad2s1210_channels[] = {
	{
		.type = IIO_ANGL,
		.indexed = 1,
		.channel = 0,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
	}, {
		.type = IIO_ANGL_VEL,
		.indexed = 1,
		.channel = 0,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
	}
};

static struct attribute *ad2s1210_attributes[] = {
	&iio_dev_attr_reset.dev_attr.attr,
	&iio_dev_attr_fclkin.dev_attr.attr,
	&iio_dev_attr_fexcit.dev_attr.attr,
	&iio_dev_attr_control.dev_attr.attr,
	&iio_dev_attr_bits.dev_attr.attr,
	&iio_dev_attr_fault.dev_attr.attr,
	&iio_dev_attr_los_thrd.dev_attr.attr,
	&iio_dev_attr_dos_ovr_thrd.dev_attr.attr,
	&iio_dev_attr_dos_mis_thrd.dev_attr.attr,
	&iio_dev_attr_dos_rst_max_thrd.dev_attr.attr,
	&iio_dev_attr_dos_rst_min_thrd.dev_attr.attr,
	&iio_dev_attr_lot_high_thrd.dev_attr.attr,
	&iio_dev_attr_lot_low_thrd.dev_attr.attr,
	NULL,
};

static const struct attribute_group ad2s1210_attribute_group = {
	.attrs = ad2s1210_attributes,
};

static int ad2s1210_initial(struct ad2s1210_state *st)
{
	unsigned char data;
	int ret;

	mutex_lock(&st->lock);
	if (st->pdata->gpioin)
		st->resolution = ad2s1210_read_resolution_pin(st);
	else
		ad2s1210_set_resolution_pin(st);

	ret = ad2s1210_config_write(st, AD2S1210_REG_CONTROL);
	if (ret < 0)
		goto error_ret;
	data = AD2S1210_DEF_CONTROL & ~(AD2S1210_SET_RESOLUTION);
	data |= (st->resolution - 10) >> 1;
	ret = ad2s1210_config_write(st, data);
	if (ret < 0)
		goto error_ret;
	ret = ad2s1210_config_read(st, AD2S1210_REG_CONTROL);
	if (ret < 0)
		goto error_ret;

	if (ret & AD2S1210_MSB_IS_HIGH) {
		ret = -EIO;
		goto error_ret;
	}

	ret = ad2s1210_update_frequency_control_word(st);
	if (ret < 0)
		goto error_ret;
	ret = ad2s1210_soft_reset(st);
error_ret:
	mutex_unlock(&st->lock);
	return ret;
}

static const struct iio_info ad2s1210_info = {
	.read_raw = &ad2s1210_read_raw,
	.attrs = &ad2s1210_attribute_group,
	.driver_module = THIS_MODULE,
};

static int ad2s1210_setup_gpios(struct ad2s1210_state *st)
{
	unsigned long flags = st->pdata->gpioin ? GPIOF_DIR_IN : GPIOF_DIR_OUT;
	struct gpio ad2s1210_gpios[] = {
		{ st->pdata->sample, GPIOF_DIR_IN, "sample" },
		{ st->pdata->a[0], flags, "a0" },
		{ st->pdata->a[1], flags, "a1" },
		{ st->pdata->res[0], flags, "res0" },
		{ st->pdata->res[0], flags, "res1" },
	};

	return gpio_request_array(ad2s1210_gpios, ARRAY_SIZE(ad2s1210_gpios));
}

static void ad2s1210_free_gpios(struct ad2s1210_state *st)
{
	unsigned long flags = st->pdata->gpioin ? GPIOF_DIR_IN : GPIOF_DIR_OUT;
	struct gpio ad2s1210_gpios[] = {
		{ st->pdata->sample, GPIOF_DIR_IN, "sample" },
		{ st->pdata->a[0], flags, "a0" },
		{ st->pdata->a[1], flags, "a1" },
		{ st->pdata->res[0], flags, "res0" },
		{ st->pdata->res[0], flags, "res1" },
	};

	gpio_free_array(ad2s1210_gpios, ARRAY_SIZE(ad2s1210_gpios));
}

static int ad2s1210_probe(struct spi_device *spi)
{
	struct iio_dev *indio_dev;
	struct ad2s1210_state *st;
	int ret;

	if (spi->dev.platform_data == NULL)
		return -EINVAL;

	indio_dev = iio_device_alloc(sizeof(*st));
	if (indio_dev == NULL) {
		ret = -ENOMEM;
		goto error_ret;
	}
	st = iio_priv(indio_dev);
	st->pdata = spi->dev.platform_data;
	ret = ad2s1210_setup_gpios(st);
	if (ret < 0)
		goto error_free_dev;

	spi_set_drvdata(spi, indio_dev);

	mutex_init(&st->lock);
	st->sdev = spi;
	st->hysteresis = true;
	st->mode = MOD_CONFIG;
	st->resolution = 12;
	st->fexcit = AD2S1210_DEF_EXCIT;

	indio_dev->dev.parent = &spi->dev;
	indio_dev->info = &ad2s1210_info;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = ad2s1210_channels;
	indio_dev->num_channels = ARRAY_SIZE(ad2s1210_channels);
	indio_dev->name = spi_get_device_id(spi)->name;

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

	st->fclkin = spi->max_speed_hz;
	spi->mode = SPI_MODE_3;
	spi_setup(spi);
	ad2s1210_initial(st);

	return 0;

error_free_gpios:
	ad2s1210_free_gpios(st);
error_free_dev:
	iio_device_free(indio_dev);
error_ret:
	return ret;
}

static int ad2s1210_remove(struct spi_device *spi)
{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);

	iio_device_unregister(indio_dev);
	ad2s1210_free_gpios(iio_priv(indio_dev));
	iio_device_free(indio_dev);

	return 0;
}

static const struct spi_device_id ad2s1210_id[] = {
	{ "ad2s1210" },
	{}
};
MODULE_DEVICE_TABLE(spi, ad2s1210_id);

static struct spi_driver ad2s1210_driver = {
	.driver = {
		.name = DRV_NAME,
		.owner = THIS_MODULE,
	},
	.probe = ad2s1210_probe,
	.remove = ad2s1210_remove,
	.id_table = ad2s1210_id,
};
module_spi_driver(ad2s1210_driver);

MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
MODULE_DESCRIPTION("Analog Devices AD2S1210 Resolver to Digital SPI driver");
MODULE_LICENSE("GPL v2");