// SPDX-License-Identifier: GPL-2.0-only
/*
 * IIO DAC driver for NXP LPC18xx DAC
 *
 * Copyright (C) 2016 Joachim Eastwood <manabian@gmail.com>
 *
 * UNSUPPORTED hardware features:
 *  - Interrupts
 *  - DMA
 */

#include <linux/clk.h>
#include <linux/err.h>
#include <linux/iio/iio.h>
#include <linux/iio/driver.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>

/* LPC18XX DAC registers and bits */
#define LPC18XX_DAC_CR                  0x000
#define  LPC18XX_DAC_CR_VALUE_SHIFT     6
#define  LPC18XX_DAC_CR_VALUE_MASK      0x3ff
#define  LPC18XX_DAC_CR_BIAS            BIT(16)
#define LPC18XX_DAC_CTRL                0x004
#define  LPC18XX_DAC_CTRL_DMA_ENA       BIT(3)

struct lpc18xx_dac {
        struct regulator *vref;
        void __iomem *base;
        struct mutex lock;
        struct clk *clk;
};

static const struct iio_chan_spec lpc18xx_dac_iio_channels[] = {
        {
                .type = IIO_VOLTAGE,
                .output = 1,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                                      BIT(IIO_CHAN_INFO_SCALE),
        },
};

static int lpc18xx_dac_read_raw(struct iio_dev *indio_dev,
                                struct iio_chan_spec const *chan,
                                int *val, int *val2, long mask)
{
        struct lpc18xx_dac *dac = iio_priv(indio_dev);
        u32 reg;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                reg = readl(dac->base + LPC18XX_DAC_CR);
                *val = reg >> LPC18XX_DAC_CR_VALUE_SHIFT;
                *val &= LPC18XX_DAC_CR_VALUE_MASK;

                return IIO_VAL_INT;

        case IIO_CHAN_INFO_SCALE:
                *val = regulator_get_voltage(dac->vref) / 1000;
                *val2 = 10;

                return IIO_VAL_FRACTIONAL_LOG2;
        }

        return -EINVAL;
}

static int lpc18xx_dac_write_raw(struct iio_dev *indio_dev,
                                 struct iio_chan_spec const *chan,
                                 int val, int val2, long mask)
{
        struct lpc18xx_dac *dac = iio_priv(indio_dev);
        u32 reg;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                if (val < 0 || val > LPC18XX_DAC_CR_VALUE_MASK)
                        return -EINVAL;

                reg = LPC18XX_DAC_CR_BIAS;
                reg |= val << LPC18XX_DAC_CR_VALUE_SHIFT;

                mutex_lock(&dac->lock);
                writel(reg, dac->base + LPC18XX_DAC_CR);
                writel(LPC18XX_DAC_CTRL_DMA_ENA, dac->base + LPC18XX_DAC_CTRL);
                mutex_unlock(&dac->lock);

                return 0;
        }

        return -EINVAL;
}

static const struct iio_info lpc18xx_dac_info = {
        .read_raw = lpc18xx_dac_read_raw,
        .write_raw = lpc18xx_dac_write_raw,
};

static int lpc18xx_dac_probe(struct platform_device *pdev)
{
        struct iio_dev *indio_dev;
        struct lpc18xx_dac *dac;
        int ret;

        indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*dac));
        if (!indio_dev)
                return -ENOMEM;

        platform_set_drvdata(pdev, indio_dev);
        dac = iio_priv(indio_dev);
        mutex_init(&dac->lock);

        dac->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(dac->base))
                return PTR_ERR(dac->base);

        dac->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(dac->clk))
                return dev_err_probe(&pdev->dev, PTR_ERR(dac->clk),
                                     "error getting clock\n");

        dac->vref = devm_regulator_get(&pdev->dev, "vref");
        if (IS_ERR(dac->vref))
                return dev_err_probe(&pdev->dev, PTR_ERR(dac->vref),
                                     "error getting regulator\n");

        indio_dev->name = dev_name(&pdev->dev);
        indio_dev->info = &lpc18xx_dac_info;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = lpc18xx_dac_iio_channels;
        indio_dev->num_channels = ARRAY_SIZE(lpc18xx_dac_iio_channels);

        ret = regulator_enable(dac->vref);
        if (ret) {
                dev_err(&pdev->dev, "unable to enable regulator\n");
                return ret;
        }

        ret = clk_prepare_enable(dac->clk);
        if (ret) {
                dev_err(&pdev->dev, "unable to enable clock\n");
                goto dis_reg;
        }

        writel(0, dac->base + LPC18XX_DAC_CTRL);
        writel(0, dac->base + LPC18XX_DAC_CR);

        ret = iio_device_register(indio_dev);
        if (ret) {
                dev_err(&pdev->dev, "unable to register device\n");
                goto dis_clk;
        }

        return 0;

dis_clk:
        clk_disable_unprepare(dac->clk);
dis_reg:
        regulator_disable(dac->vref);
        return ret;
}

static void lpc18xx_dac_remove(struct platform_device *pdev)
{
        struct iio_dev *indio_dev = platform_get_drvdata(pdev);
        struct lpc18xx_dac *dac = iio_priv(indio_dev);

        iio_device_unregister(indio_dev);

        writel(0, dac->base + LPC18XX_DAC_CTRL);
        clk_disable_unprepare(dac->clk);
        regulator_disable(dac->vref);
}

static const struct of_device_id lpc18xx_dac_match[] = {
        { .compatible = "nxp,lpc1850-dac" },
        { }
};
MODULE_DEVICE_TABLE(of, lpc18xx_dac_match);

static struct platform_driver lpc18xx_dac_driver = {
        .probe = lpc18xx_dac_probe,
        .remove = lpc18xx_dac_remove,
        .driver = {
                .name = "lpc18xx-dac",
                .of_match_table = lpc18xx_dac_match,
        },
};
module_platform_driver(lpc18xx_dac_driver);

MODULE_DESCRIPTION("LPC18xx DAC driver");
MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
MODULE_LICENSE("GPL v2");