/*
 * ADE7759 Active Energy Metering IC with di/dt Sensor Interface Driver
 *
 * Copyright 2010 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/spi/spi.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/list.h>
#include <linux/module.h>

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

#define ADE7759_WAVEFORM  0x01
#define ADE7759_AENERGY   0x02
#define ADE7759_RSTENERGY 0x03
#define ADE7759_STATUS    0x04
#define ADE7759_RSTSTATUS 0x05
#define ADE7759_MODE      0x06
#define ADE7759_CFDEN     0x07
#define ADE7759_CH1OS     0x08
#define ADE7759_CH2OS     0x09
#define ADE7759_GAIN      0x0A
#define ADE7759_APGAIN    0x0B
#define ADE7759_PHCAL     0x0C
#define ADE7759_APOS      0x0D
#define ADE7759_ZXTOUT    0x0E
#define ADE7759_SAGCYC    0x0F
#define ADE7759_IRQEN     0x10
#define ADE7759_SAGLVL    0x11
#define ADE7759_TEMP      0x12
#define ADE7759_LINECYC   0x13
#define ADE7759_LENERGY   0x14
#define ADE7759_CFNUM     0x15
#define ADE7759_CHKSUM    0x1E
#define ADE7759_DIEREV    0x1F

#define ADE7759_READ_REG(a)    a
#define ADE7759_WRITE_REG(a) ((a) | 0x80)

#define ADE7759_MAX_TX    6
#define ADE7759_MAX_RX    6
#define ADE7759_STARTUP_DELAY 1000

#define ADE7759_SPI_SLOW	(u32)(300 * 1000)
#define ADE7759_SPI_BURST	(u32)(1000 * 1000)
#define ADE7759_SPI_FAST	(u32)(2000 * 1000)

/**
 * struct ade7759_state - device instance specific data
 * @us:			actual spi_device
 * @buf_lock:		mutex to protect tx and rx
 * @tx:			transmit buffer
 * @rx:			receive buffer
 **/
struct ade7759_state {
	struct spi_device	*us;
	struct mutex		buf_lock;
	u8			tx[ADE7759_MAX_TX] ____cacheline_aligned;
	u8			rx[ADE7759_MAX_RX];
};

static int ade7759_spi_write_reg_8(struct device *dev,
		u8 reg_address,
		u8 val)
{
	int ret;
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct ade7759_state *st = iio_priv(indio_dev);

	mutex_lock(&st->buf_lock);
	st->tx[0] = ADE7759_WRITE_REG(reg_address);
	st->tx[1] = val;

	ret = spi_write(st->us, st->tx, 2);
	mutex_unlock(&st->buf_lock);

	return ret;
}

static int ade7759_spi_write_reg_16(struct device *dev,
		u8 reg_address,
		u16 value)
{
	int ret;
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct ade7759_state *st = iio_priv(indio_dev);

	mutex_lock(&st->buf_lock);
	st->tx[0] = ADE7759_WRITE_REG(reg_address);
	st->tx[1] = (value >> 8) & 0xFF;
	st->tx[2] = value & 0xFF;
	ret = spi_write(st->us, st->tx, 3);
	mutex_unlock(&st->buf_lock);

	return ret;
}

static int ade7759_spi_read_reg_8(struct device *dev,
		u8 reg_address,
		u8 *val)
{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct ade7759_state *st = iio_priv(indio_dev);
	int ret;

	ret = spi_w8r8(st->us, ADE7759_READ_REG(reg_address));
	if (ret < 0) {
		dev_err(&st->us->dev, "problem when reading 8 bit register 0x%02X",
				reg_address);
		return ret;
	}
	*val = ret;

	return 0;
}

static int ade7759_spi_read_reg_16(struct device *dev,
		u8 reg_address,
		u16 *val)
{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct ade7759_state *st = iio_priv(indio_dev);
	int ret;

	ret = spi_w8r16be(st->us, ADE7759_READ_REG(reg_address));
	if (ret < 0) {
		dev_err(&st->us->dev, "problem when reading 16 bit register 0x%02X",
			reg_address);
		return ret;
	}

	*val = ret;

	return 0;
}

static int ade7759_spi_read_reg_40(struct device *dev,
		u8 reg_address,
		u64 *val)
{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct ade7759_state *st = iio_priv(indio_dev);
	int ret;
	struct spi_transfer xfers[] = {
		{
			.tx_buf = st->tx,
			.rx_buf = st->rx,
			.bits_per_word = 8,
			.len = 6,
		},
	};

	mutex_lock(&st->buf_lock);
	st->tx[0] = ADE7759_READ_REG(reg_address);
	memset(&st->tx[1], 0, 5);

	ret = spi_sync_transfer(st->us, xfers, ARRAY_SIZE(xfers));
	if (ret) {
		dev_err(&st->us->dev, "problem when reading 40 bit register 0x%02X",
				reg_address);
		goto error_ret;
	}
	*val = ((u64)st->rx[1] << 32) | (st->rx[2] << 24) |
		(st->rx[3] << 16) | (st->rx[4] << 8) | st->rx[5];

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

static ssize_t ade7759_read_8bit(struct device *dev,
		struct device_attribute *attr,
		char *buf)
{
	int ret;
	u8 val = 0;
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);

	ret = ade7759_spi_read_reg_8(dev, this_attr->address, &val);
	if (ret)
		return ret;

	return sprintf(buf, "%u\n", val);
}

static ssize_t ade7759_read_16bit(struct device *dev,
		struct device_attribute *attr,
		char *buf)
{
	int ret;
	u16 val = 0;
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);

	ret = ade7759_spi_read_reg_16(dev, this_attr->address, &val);
	if (ret)
		return ret;

	return sprintf(buf, "%u\n", val);
}

static ssize_t ade7759_read_40bit(struct device *dev,
		struct device_attribute *attr,
		char *buf)
{
	int ret;
	u64 val = 0;
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);

	ret = ade7759_spi_read_reg_40(dev, this_attr->address, &val);
	if (ret)
		return ret;

	return sprintf(buf, "%llu\n", val);
}

static ssize_t ade7759_write_8bit(struct device *dev,
		struct device_attribute *attr,
		const char *buf,
		size_t len)
{
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
	int ret;
	u8 val;

	ret = kstrtou8(buf, 10, &val);
	if (ret)
		goto error_ret;
	ret = ade7759_spi_write_reg_8(dev, this_attr->address, val);

error_ret:
	return ret ? ret : len;
}

static ssize_t ade7759_write_16bit(struct device *dev,
		struct device_attribute *attr,
		const char *buf,
		size_t len)
{
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
	int ret;
	u16 val;

	ret = kstrtou16(buf, 10, &val);
	if (ret)
		goto error_ret;
	ret = ade7759_spi_write_reg_16(dev, this_attr->address, val);

error_ret:
	return ret ? ret : len;
}

static int ade7759_reset(struct device *dev)
{
	int ret;
	u16 val;

	ret = ade7759_spi_read_reg_16(dev,
			ADE7759_MODE,
			&val);
	if (ret < 0)
		return ret;

	val |= BIT(6); /* Software Chip Reset */
	return ade7759_spi_write_reg_16(dev,
			ADE7759_MODE,
			val);
}

static IIO_DEV_ATTR_AENERGY(ade7759_read_40bit, ADE7759_AENERGY);
static IIO_DEV_ATTR_CFDEN(0644,
		ade7759_read_16bit,
		ade7759_write_16bit,
		ADE7759_CFDEN);
static IIO_DEV_ATTR_CFNUM(0644,
		ade7759_read_8bit,
		ade7759_write_8bit,
		ADE7759_CFNUM);
static IIO_DEV_ATTR_CHKSUM(ade7759_read_8bit, ADE7759_CHKSUM);
static IIO_DEV_ATTR_PHCAL(0644,
		ade7759_read_16bit,
		ade7759_write_16bit,
		ADE7759_PHCAL);
static IIO_DEV_ATTR_APOS(0644,
		ade7759_read_16bit,
		ade7759_write_16bit,
		ADE7759_APOS);
static IIO_DEV_ATTR_SAGCYC(0644,
		ade7759_read_8bit,
		ade7759_write_8bit,
		ADE7759_SAGCYC);
static IIO_DEV_ATTR_SAGLVL(0644,
		ade7759_read_8bit,
		ade7759_write_8bit,
		ADE7759_SAGLVL);
static IIO_DEV_ATTR_LINECYC(0644,
		ade7759_read_8bit,
		ade7759_write_8bit,
		ADE7759_LINECYC);
static IIO_DEV_ATTR_LENERGY(ade7759_read_40bit, ADE7759_LENERGY);
static IIO_DEV_ATTR_PGA_GAIN(0644,
		ade7759_read_8bit,
		ade7759_write_8bit,
		ADE7759_GAIN);
static IIO_DEV_ATTR_ACTIVE_POWER_GAIN(0644,
		ade7759_read_16bit,
		ade7759_write_16bit,
		ADE7759_APGAIN);
static IIO_DEV_ATTR_CH_OFF(1, 0644,
		ade7759_read_8bit,
		ade7759_write_8bit,
		ADE7759_CH1OS);
static IIO_DEV_ATTR_CH_OFF(2, 0644,
		ade7759_read_8bit,
		ade7759_write_8bit,
		ADE7759_CH2OS);

static int ade7759_set_irq(struct device *dev, bool enable)
{
	int ret;
	u8 irqen;

	ret = ade7759_spi_read_reg_8(dev, ADE7759_IRQEN, &irqen);
	if (ret)
		goto error_ret;

	if (enable)
		irqen |= BIT(3); /* Enables an interrupt when a data is
				  * present in the waveform register
				  */
	else
		irqen &= ~BIT(3);

	ret = ade7759_spi_write_reg_8(dev, ADE7759_IRQEN, irqen);

error_ret:
	return ret;
}

/* Power down the device */
static int ade7759_stop_device(struct device *dev)
{
	int ret;
	u16 val;

	ret = ade7759_spi_read_reg_16(dev,
			ADE7759_MODE,
			&val);
	if (ret < 0) {
		dev_err(dev, "unable to power down the device, error: %d\n",
			ret);
		return ret;
	}

	val |= BIT(4);  /* AD converters can be turned off */

	return ade7759_spi_write_reg_16(dev, ADE7759_MODE, val);
}

static int ade7759_initial_setup(struct iio_dev *indio_dev)
{
	int ret;
	struct ade7759_state *st = iio_priv(indio_dev);
	struct device *dev = &indio_dev->dev;

	/* use low spi speed for init */
	st->us->mode = SPI_MODE_3;
	spi_setup(st->us);

	/* Disable IRQ */
	ret = ade7759_set_irq(dev, false);
	if (ret) {
		dev_err(dev, "disable irq failed");
		goto err_ret;
	}

	ade7759_reset(dev);
	usleep_range(ADE7759_STARTUP_DELAY, ADE7759_STARTUP_DELAY + 100);

err_ret:
	return ret;
}

static ssize_t ade7759_read_frequency(struct device *dev,
		struct device_attribute *attr,
		char *buf)
{
	int ret;
	u16 t;
	int sps;

	ret = ade7759_spi_read_reg_16(dev,
			ADE7759_MODE,
			&t);
	if (ret)
		return ret;

	t = (t >> 3) & 0x3;
	sps = 27900 / (1 + t);

	return sprintf(buf, "%d\n", sps);
}

static ssize_t ade7759_write_frequency(struct device *dev,
		struct device_attribute *attr,
		const char *buf,
		size_t len)
{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct ade7759_state *st = iio_priv(indio_dev);
	u16 val;
	int ret;
	u16 reg, t;

	ret = kstrtou16(buf, 10, &val);
	if (ret)
		return ret;
	if (!val)
		return -EINVAL;

	mutex_lock(&indio_dev->mlock);

	t = 27900 / val;
	if (t > 0)
		t--;

	if (t > 1)
		st->us->max_speed_hz = ADE7759_SPI_SLOW;
	else
		st->us->max_speed_hz = ADE7759_SPI_FAST;

	ret = ade7759_spi_read_reg_16(dev, ADE7759_MODE, &reg);
	if (ret)
		goto out;

	reg &= ~(3 << 13);
	reg |= t << 13;

	ret = ade7759_spi_write_reg_16(dev, ADE7759_MODE, reg);

out:
	mutex_unlock(&indio_dev->mlock);

	return ret ? ret : len;
}
static IIO_DEV_ATTR_TEMP_RAW(ade7759_read_8bit);
static IIO_CONST_ATTR(in_temp_offset, "70 C");
static IIO_CONST_ATTR(in_temp_scale, "1 C");

static IIO_DEV_ATTR_SAMP_FREQ(0644,
		ade7759_read_frequency,
		ade7759_write_frequency);

static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("27900 14000 7000 3500");

static struct attribute *ade7759_attributes[] = {
	&iio_dev_attr_in_temp_raw.dev_attr.attr,
	&iio_const_attr_in_temp_offset.dev_attr.attr,
	&iio_const_attr_in_temp_scale.dev_attr.attr,
	&iio_dev_attr_sampling_frequency.dev_attr.attr,
	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
	&iio_dev_attr_phcal.dev_attr.attr,
	&iio_dev_attr_cfden.dev_attr.attr,
	&iio_dev_attr_aenergy.dev_attr.attr,
	&iio_dev_attr_cfnum.dev_attr.attr,
	&iio_dev_attr_apos.dev_attr.attr,
	&iio_dev_attr_sagcyc.dev_attr.attr,
	&iio_dev_attr_saglvl.dev_attr.attr,
	&iio_dev_attr_linecyc.dev_attr.attr,
	&iio_dev_attr_lenergy.dev_attr.attr,
	&iio_dev_attr_chksum.dev_attr.attr,
	&iio_dev_attr_pga_gain.dev_attr.attr,
	&iio_dev_attr_active_power_gain.dev_attr.attr,
	&iio_dev_attr_choff_1.dev_attr.attr,
	&iio_dev_attr_choff_2.dev_attr.attr,
	NULL,
};

static const struct attribute_group ade7759_attribute_group = {
	.attrs = ade7759_attributes,
};

static const struct iio_info ade7759_info = {
	.attrs = &ade7759_attribute_group,
	.driver_module = THIS_MODULE,
};

static int ade7759_probe(struct spi_device *spi)
{
	int ret;
	struct ade7759_state *st;
	struct iio_dev *indio_dev;

	/* setup the industrialio driver allocated elements */
	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
	if (!indio_dev)
		return -ENOMEM;
	/* this is only used for removal purposes */
	spi_set_drvdata(spi, indio_dev);

	st = iio_priv(indio_dev);
	st->us = spi;
	mutex_init(&st->buf_lock);
	indio_dev->name = spi->dev.driver->name;
	indio_dev->dev.parent = &spi->dev;
	indio_dev->info = &ade7759_info;
	indio_dev->modes = INDIO_DIRECT_MODE;

	/* Get the device into a sane initial state */
	ret = ade7759_initial_setup(indio_dev);
	if (ret)
		return ret;

	return iio_device_register(indio_dev);
}

static int ade7759_remove(struct spi_device *spi)
{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);

	iio_device_unregister(indio_dev);
	ade7759_stop_device(&indio_dev->dev);

	return 0;
}

static struct spi_driver ade7759_driver = {
	.driver = {
		.name = "ade7759",
	},
	.probe = ade7759_probe,
	.remove = ade7759_remove,
};
module_spi_driver(ade7759_driver);

MODULE_AUTHOR("Barry Song <21cnbao@gmail.com>");
MODULE_DESCRIPTION("Analog Devices ADE7759 Active Energy Metering IC Driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("spi:ad7759");