/*
 * kxsd9.c	simple support for the Kionix KXSD9 3D
 *		accelerometer.
 *
 * Copyright (c) 2008-2009 Jonathan Cameron <jic23@cam.ac.uk>
 *
 * 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.
 *
 * The i2c interface is very similar, so shouldn't be a problem once
 * I have a suitable wire made up.
 *
 * TODO:	Support the motion detector
 *		Uses register address incrementing so could have a
 *		heavily optimized ring buffer access function.
 */

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/spi/spi.h>
#include <linux/sysfs.h>
#include <linux/slab.h>

#include "../iio.h"
#include "../sysfs.h"
#include "../adc/adc.h"
#include "accel.h"

#define KXSD9_REG_X		0x00
#define KXSD9_REG_Y		0x02
#define KXSD9_REG_Z		0x04
#define KXSD9_REG_AUX		0x06
#define KXSD9_REG_RESET		0x0a
#define KXSD9_REG_CTRL_C	0x0c

#define KXSD9_FS_8		0x00
#define KXSD9_FS_6		0x01
#define KXSD9_FS_4		0x02
#define KXSD9_FS_2		0x03
#define KXSD9_FS_MASK		0x03

#define KXSD9_REG_CTRL_B	0x0d
#define KXSD9_REG_CTRL_A	0x0e

#define KXSD9_READ(a) (0x80 | (a))
#define KXSD9_WRITE(a) (a)

#define KXSD9_SCALE_2G "0.011978"
#define KXSD9_SCALE_4G "0.023927"
#define KXSD9_SCALE_6G "0.035934"
#define KXSD9_SCALE_8G "0.047853"

#define KXSD9_STATE_RX_SIZE 2
#define KXSD9_STATE_TX_SIZE 4
/**
 * struct kxsd9_state - device related storage
 * @buf_lock:	protect the rx and tx buffers.
 * @us:		spi device
 * @rx:		single rx buffer storage
 * @tx:		single tx buffer storage
 **/
struct kxsd9_state {
	struct mutex buf_lock;
	struct spi_device *us;
	u8 rx[KXSD9_STATE_RX_SIZE] ____cacheline_aligned;
	u8 tx[KXSD9_STATE_TX_SIZE];
};

/* This may want to move to mili g to allow for non integer ranges */
static ssize_t kxsd9_read_scale(struct device *dev,
				struct device_attribute *attr,
				char *buf)
{
	int ret;
	ssize_t len = 0;
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct kxsd9_state *st = iio_priv(indio_dev);
	struct spi_transfer xfer = {
		.bits_per_word = 8,
		.len = 2,
		.cs_change = 1,
		.tx_buf = st->tx,
		.rx_buf = st->rx,
	};
	struct spi_message msg;

	mutex_lock(&st->buf_lock);
	st->tx[0] = KXSD9_READ(KXSD9_REG_CTRL_C);
	st->tx[1] = 0;
	spi_message_init(&msg);
	spi_message_add_tail(&xfer, &msg);
	ret = spi_sync(st->us, &msg);
	if (ret)
		goto error_ret;

	switch (st->rx[1] & KXSD9_FS_MASK) {
	case KXSD9_FS_8:
		len += sprintf(buf, "%s\n", KXSD9_SCALE_8G);
		break;
	case KXSD9_FS_6:
		len += sprintf(buf, "%s\n", KXSD9_SCALE_6G);
		break;
	case KXSD9_FS_4:
		len += sprintf(buf, "%s\n", KXSD9_SCALE_4G);
		break;
	case KXSD9_FS_2:
		len += sprintf(buf, "%s\n", KXSD9_SCALE_2G);
		break;
	}

error_ret:
	mutex_unlock(&st->buf_lock);

	return ret ? ret : len;
}
static ssize_t kxsd9_write_scale(struct device *dev,
				 struct device_attribute *attr,
				 const char *buf,
				 size_t len)
{

	struct spi_message msg;
	int ret;
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct kxsd9_state *st = iio_priv(indio_dev);
	u8 val;
	struct spi_transfer xfers[] = {
		{
			.bits_per_word = 8,
			.len = 2,
			.cs_change = 1,
			.tx_buf = st->tx,
			.rx_buf = st->rx,
		}, {
			.bits_per_word = 8,
			.len = 2,
			.cs_change = 1,
			.tx_buf = st->tx,
		},
	};

	if (!strncmp(buf, KXSD9_SCALE_8G,
		     strlen(buf) < strlen(KXSD9_SCALE_8G)
		     ? strlen(buf) : strlen(KXSD9_SCALE_8G)))
		val = KXSD9_FS_8;
	else if (!strncmp(buf, KXSD9_SCALE_6G,
			  strlen(buf) < strlen(KXSD9_SCALE_6G)
			  ? strlen(buf) : strlen(KXSD9_SCALE_6G)))
		val = KXSD9_FS_6;
	else if (!strncmp(buf, KXSD9_SCALE_4G,
			  strlen(buf) < strlen(KXSD9_SCALE_4G)
			  ? strlen(buf) : strlen(KXSD9_SCALE_4G)))
		val = KXSD9_FS_4;
	else if (!strncmp(buf, KXSD9_SCALE_2G,
			  strlen(buf) < strlen(KXSD9_SCALE_2G)
			  ? strlen(buf) : strlen(KXSD9_SCALE_2G)))
		val = KXSD9_FS_2;
	else
		return -EINVAL;

	mutex_lock(&st->buf_lock);
	st->tx[0] = KXSD9_READ(KXSD9_REG_CTRL_C);
	st->tx[1] = 0;
	spi_message_init(&msg);
	spi_message_add_tail(&xfers[0], &msg);
	ret = spi_sync(st->us, &msg);
	if (ret)
		goto error_ret;
	st->tx[0] = KXSD9_WRITE(KXSD9_REG_CTRL_C);
	st->tx[1] = (st->rx[1] & ~KXSD9_FS_MASK) | val;

	spi_message_init(&msg);
	spi_message_add_tail(&xfers[1], &msg);
	ret = spi_sync(st->us, &msg);
error_ret:
	mutex_unlock(&st->buf_lock);
	return ret ? ret : len;
}

static ssize_t kxsd9_read_accel(struct device *dev,
				struct device_attribute *attr,
				char *buf)
{
	struct spi_message msg;
	int ret;
	ssize_t len = 0;
	u16 val;
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct kxsd9_state *st = iio_priv(indio_dev);
	struct spi_transfer xfers[] = {
		{
			.bits_per_word = 8,
			.len = 1,
			.cs_change = 0,
			.delay_usecs = 200,
			.tx_buf = st->tx,
		}, {
			.bits_per_word = 8,
			.len = 2,
			.cs_change = 1,
			.rx_buf = st->rx,
		},
	};

	mutex_lock(&st->buf_lock);
	st->tx[0] = KXSD9_READ(this_attr->address);
	spi_message_init(&msg);
	spi_message_add_tail(&xfers[0], &msg);
	spi_message_add_tail(&xfers[1], &msg);
	ret = spi_sync(st->us, &msg);
	if (ret)
		goto error_ret;
	val = (((u16)(st->rx[0])) << 8) | (st->rx[1] & 0xF0);
	len = sprintf(buf, "%d\n", val);
error_ret:
	mutex_unlock(&st->buf_lock);

	return ret ? ret : len;
}

static IIO_DEV_ATTR_ACCEL_X(kxsd9_read_accel, KXSD9_REG_X);
static IIO_DEV_ATTR_ACCEL_Y(kxsd9_read_accel, KXSD9_REG_Y);
static IIO_DEV_ATTR_ACCEL_Z(kxsd9_read_accel, KXSD9_REG_Z);
static IIO_DEV_ATTR_IN_RAW(0, kxsd9_read_accel, KXSD9_REG_AUX);

static IIO_DEVICE_ATTR(accel_scale,
		S_IRUGO | S_IWUSR,
		kxsd9_read_scale,
		kxsd9_write_scale,
		0);

static IIO_CONST_ATTR(accel_scale_available,
		KXSD9_SCALE_2G " "
		KXSD9_SCALE_4G " "
		KXSD9_SCALE_6G " "
		KXSD9_SCALE_8G);

static struct attribute *kxsd9_attributes[] = {
	&iio_dev_attr_accel_x_raw.dev_attr.attr,
	&iio_dev_attr_accel_y_raw.dev_attr.attr,
	&iio_dev_attr_accel_z_raw.dev_attr.attr,
	&iio_dev_attr_in0_raw.dev_attr.attr,
	&iio_dev_attr_accel_scale.dev_attr.attr,
	&iio_const_attr_accel_scale_available.dev_attr.attr,
	NULL,
};

static const struct attribute_group kxsd9_attribute_group = {
	.attrs = kxsd9_attributes,
};

static int __devinit kxsd9_power_up(struct kxsd9_state *st)
{
	struct spi_transfer xfers[2] = {
		{
			.bits_per_word = 8,
			.len = 2,
			.cs_change = 1,
			.tx_buf = st->tx,
		}, {
			.bits_per_word = 8,
			.len = 2,
			.cs_change = 1,
			.tx_buf = st->tx + 2,
		},
	};
	struct spi_message msg;
	st->tx[0] = 0x0d;
	st->tx[1] = 0x40;
	st->tx[2] = 0x0c;
	st->tx[3] = 0x9b;

	spi_message_init(&msg);
	spi_message_add_tail(&xfers[0], &msg);
	spi_message_add_tail(&xfers[1], &msg);

	return spi_sync(st->us, &msg);
};

static const struct iio_info kxsd9_info = {
	.attrs = &kxsd9_attribute_group,
	.driver_module = THIS_MODULE,
};

static int __devinit kxsd9_probe(struct spi_device *spi)
{
	struct iio_dev *indio_dev;
	struct kxsd9_state *st;
	int ret = 0;

	indio_dev = iio_allocate_device(sizeof(*st));
	if (indio_dev == NULL) {
		ret = -ENOMEM;
		goto error_ret;
	}
	st = iio_priv(indio_dev);
	spi_set_drvdata(spi, indio_dev);

	st->us = spi;
	mutex_init(&st->buf_lock);

	indio_dev->dev.parent = &spi->dev;
	indio_dev->info = &kxsd9_info;
	indio_dev->modes = INDIO_DIRECT_MODE;

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

	spi->mode = SPI_MODE_0;
	spi_setup(spi);
	kxsd9_power_up(st);

	return 0;

error_free_dev:
	iio_free_device(indio_dev);
error_ret:
	return ret;
}

static int __devexit kxsd9_remove(struct spi_device *spi)
{
	iio_device_unregister(spi_get_drvdata(spi));

	return 0;
}

static struct spi_driver kxsd9_driver = {
	.driver = {
		.name = "kxsd9",
		.owner = THIS_MODULE,
	},
	.probe = kxsd9_probe,
	.remove = __devexit_p(kxsd9_remove),
};

static __init int kxsd9_spi_init(void)
{
	return spi_register_driver(&kxsd9_driver);
}
module_init(kxsd9_spi_init);

static __exit void kxsd9_spi_exit(void)
{
	spi_unregister_driver(&kxsd9_driver);
}
module_exit(kxsd9_spi_exit);

MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
MODULE_DESCRIPTION("Kionix KXSD9 SPI driver");
MODULE_LICENSE("GPL v2");