// SPDX-License-Identifier: GPL-2.0+
/*
 * ADC driver for the RICOH RN5T618 power management chip family
 *
 * Copyright (C) 2019 Andreas Kemnade
 */

#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mfd/rn5t618.h>
#include <linux/platform_device.h>
#include <linux/completion.h>
#include <linux/regmap.h>
#include <linux/iio/iio.h>
#include <linux/slab.h>

#define RN5T618_ADC_CONVERSION_TIMEOUT   (msecs_to_jiffies(500))
#define RN5T618_REFERENCE_VOLT 2500

/* mask for selecting channels for single conversion */
#define RN5T618_ADCCNT3_CHANNEL_MASK 0x7
/* average 4-time conversion mode */
#define RN5T618_ADCCNT3_AVG BIT(3)
/* set for starting a single conversion, gets cleared by hw when done */
#define RN5T618_ADCCNT3_GODONE BIT(4)
/* automatic conversion, period is in ADCCNT2, selected channels are
 * in ADCCNT1
 */
#define RN5T618_ADCCNT3_AUTO BIT(5)
#define RN5T618_ADCEND_IRQ BIT(0)

struct rn5t618_adc_data {
	struct device *dev;
	struct rn5t618 *rn5t618;
	struct completion conv_completion;
	int irq;
};

struct rn5t618_channel_ratios {
	u16 numerator;
	u16 denominator;
};

enum rn5t618_channels {
	LIMMON = 0,
	VBAT,
	VADP,
	VUSB,
	VSYS,
	VTHM,
	AIN1,
	AIN0
};

static const struct rn5t618_channel_ratios rn5t618_ratios[8] = {
	[LIMMON] = {50, 32}, /* measured across 20mOhm, amplified by 32 */
	[VBAT] = {2, 1},
	[VADP] = {3, 1},
	[VUSB] = {3, 1},
	[VSYS] = {3, 1},
	[VTHM] = {1, 1},
	[AIN1] = {1, 1},
	[AIN0] = {1, 1},
};

static int rn5t618_read_adc_reg(struct rn5t618 *rn5t618, int reg, u16 *val)
{
	u8 data[2];
	int ret;

	ret = regmap_bulk_read(rn5t618->regmap, reg, data, sizeof(data));
	if (ret < 0)
		return ret;

	*val = (data[0] << 4) | (data[1] & 0xF);

	return 0;
}

static irqreturn_t rn5t618_adc_irq(int irq, void *data)
{
	struct rn5t618_adc_data *adc = data;
	unsigned int r = 0;
	int ret;

	/* clear low & high threshold irqs */
	regmap_write(adc->rn5t618->regmap, RN5T618_IR_ADC1, 0);
	regmap_write(adc->rn5t618->regmap, RN5T618_IR_ADC2, 0);

	ret = regmap_read(adc->rn5t618->regmap, RN5T618_IR_ADC3, &r);
	if (ret < 0)
		dev_err(adc->dev, "failed to read IRQ status: %d\n", ret);

	regmap_write(adc->rn5t618->regmap, RN5T618_IR_ADC3, 0);

	if (r & RN5T618_ADCEND_IRQ)
		complete(&adc->conv_completion);

	return IRQ_HANDLED;
}

static int rn5t618_adc_read(struct iio_dev *iio_dev,
			    const struct iio_chan_spec *chan,
			    int *val, int *val2, long mask)
{
	struct rn5t618_adc_data *adc = iio_priv(iio_dev);
	u16 raw;
	int ret;

	if (mask == IIO_CHAN_INFO_SCALE) {
		*val = RN5T618_REFERENCE_VOLT *
		       rn5t618_ratios[chan->channel].numerator;
		*val2 = rn5t618_ratios[chan->channel].denominator * 4095;

		return IIO_VAL_FRACTIONAL;
	}

	/* select channel */
	ret = regmap_update_bits(adc->rn5t618->regmap, RN5T618_ADCCNT3,
				 RN5T618_ADCCNT3_CHANNEL_MASK,
				 chan->channel);
	if (ret < 0)
		return ret;

	ret = regmap_write(adc->rn5t618->regmap, RN5T618_EN_ADCIR3,
			   RN5T618_ADCEND_IRQ);
	if (ret < 0)
		return ret;

	ret = regmap_update_bits(adc->rn5t618->regmap, RN5T618_ADCCNT3,
				 RN5T618_ADCCNT3_AVG,
				 mask == IIO_CHAN_INFO_AVERAGE_RAW ?
				 RN5T618_ADCCNT3_AVG : 0);
	if (ret < 0)
		return ret;

	init_completion(&adc->conv_completion);
	/* single conversion */
	ret = regmap_update_bits(adc->rn5t618->regmap, RN5T618_ADCCNT3,
				 RN5T618_ADCCNT3_GODONE,
				 RN5T618_ADCCNT3_GODONE);
	if (ret < 0)
		return ret;

	ret = wait_for_completion_timeout(&adc->conv_completion,
					  RN5T618_ADC_CONVERSION_TIMEOUT);
	if (ret == 0) {
		dev_warn(adc->dev, "timeout waiting for adc result\n");
		return -ETIMEDOUT;
	}

	ret = rn5t618_read_adc_reg(adc->rn5t618,
				   RN5T618_ILIMDATAH + 2 * chan->channel,
				   &raw);
	if (ret < 0)
		return ret;

	*val = raw;

	return IIO_VAL_INT;
}

static const struct iio_info rn5t618_adc_iio_info = {
	.read_raw = &rn5t618_adc_read,
};

#define RN5T618_ADC_CHANNEL(_channel, _type, _name) { \
	.type = _type, \
	.channel = _channel, \
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
			      BIT(IIO_CHAN_INFO_AVERAGE_RAW) | \
			      BIT(IIO_CHAN_INFO_SCALE), \
	.datasheet_name = _name, \
	.indexed = 1. \
}

static const struct iio_chan_spec rn5t618_adc_iio_channels[] = {
	RN5T618_ADC_CHANNEL(LIMMON, IIO_CURRENT, "LIMMON"),
	RN5T618_ADC_CHANNEL(VBAT, IIO_VOLTAGE, "VBAT"),
	RN5T618_ADC_CHANNEL(VADP, IIO_VOLTAGE, "VADP"),
	RN5T618_ADC_CHANNEL(VUSB, IIO_VOLTAGE, "VUSB"),
	RN5T618_ADC_CHANNEL(VSYS, IIO_VOLTAGE, "VSYS"),
	RN5T618_ADC_CHANNEL(VTHM, IIO_VOLTAGE, "VTHM"),
	RN5T618_ADC_CHANNEL(AIN1, IIO_VOLTAGE, "AIN1"),
	RN5T618_ADC_CHANNEL(AIN0, IIO_VOLTAGE, "AIN0")
};

static int rn5t618_adc_probe(struct platform_device *pdev)
{
	int ret;
	struct iio_dev *iio_dev;
	struct rn5t618_adc_data *adc;
	struct rn5t618 *rn5t618 = dev_get_drvdata(pdev->dev.parent);

	iio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc));
	if (!iio_dev) {
		dev_err(&pdev->dev, "failed allocating iio device\n");
		return -ENOMEM;
	}

	adc = iio_priv(iio_dev);
	adc->dev = &pdev->dev;
	adc->rn5t618 = rn5t618;

	if (rn5t618->irq_data)
		adc->irq = regmap_irq_get_virq(rn5t618->irq_data,
					       RN5T618_IRQ_ADC);

	if (adc->irq <= 0) {
		dev_err(&pdev->dev, "get virq failed\n");
		return -EINVAL;
	}

	init_completion(&adc->conv_completion);

	iio_dev->name = dev_name(&pdev->dev);
	iio_dev->info = &rn5t618_adc_iio_info;
	iio_dev->modes = INDIO_DIRECT_MODE;
	iio_dev->channels = rn5t618_adc_iio_channels;
	iio_dev->num_channels = ARRAY_SIZE(rn5t618_adc_iio_channels);

	/* stop any auto-conversion */
	ret = regmap_write(rn5t618->regmap, RN5T618_ADCCNT3, 0);
	if (ret < 0)
		return ret;

	platform_set_drvdata(pdev, iio_dev);

	ret = devm_request_threaded_irq(adc->dev, adc->irq, NULL,
					rn5t618_adc_irq,
					IRQF_ONESHOT, dev_name(adc->dev),
					adc);
	if (ret < 0) {
		dev_err(adc->dev, "request irq %d failed: %d\n", adc->irq, ret);
		return ret;
	}

	return devm_iio_device_register(adc->dev, iio_dev);
}

static struct platform_driver rn5t618_adc_driver = {
	.driver = {
		.name   = "rn5t618-adc",
	},
	.probe = rn5t618_adc_probe,
};

module_platform_driver(rn5t618_adc_driver);
MODULE_ALIAS("platform:rn5t618-adc");
MODULE_DESCRIPTION("RICOH RN5T618 ADC driver");
MODULE_LICENSE("GPL");