// SPDX-License-Identifier: GPL-2.0+
/*
 * Renesas R-Car GyroADC driver
 *
 * Copyright 2016 Marek Vasut <marek.vasut@gmail.com>
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/regulator/consumer.h>
#include <linux/of_platform.h>
#include <linux/err.h>
#include <linux/pm_runtime.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/trigger.h>

#define DRIVER_NAME                             "rcar-gyroadc"

/* GyroADC registers. */
#define RCAR_GYROADC_MODE_SELECT                0x00
#define RCAR_GYROADC_MODE_SELECT_1_MB88101A     0x0
#define RCAR_GYROADC_MODE_SELECT_2_ADCS7476     0x1
#define RCAR_GYROADC_MODE_SELECT_3_MAX1162      0x3

#define RCAR_GYROADC_START_STOP                 0x04
#define RCAR_GYROADC_START_STOP_START           BIT(0)

#define RCAR_GYROADC_CLOCK_LENGTH               0x08
#define RCAR_GYROADC_1_25MS_LENGTH              0x0c

#define RCAR_GYROADC_REALTIME_DATA(ch)          (0x10 + ((ch) * 4))
#define RCAR_GYROADC_100MS_ADDED_DATA(ch)       (0x30 + ((ch) * 4))
#define RCAR_GYROADC_10MS_AVG_DATA(ch)          (0x50 + ((ch) * 4))

#define RCAR_GYROADC_FIFO_STATUS                0x70
#define RCAR_GYROADC_FIFO_STATUS_EMPTY(ch)      BIT(0 + (4 * (ch)))
#define RCAR_GYROADC_FIFO_STATUS_FULL(ch)       BIT(1 + (4 * (ch)))
#define RCAR_GYROADC_FIFO_STATUS_ERROR(ch)      BIT(2 + (4 * (ch)))

#define RCAR_GYROADC_INTR                       0x74
#define RCAR_GYROADC_INTR_INT                   BIT(0)

#define RCAR_GYROADC_INTENR                     0x78
#define RCAR_GYROADC_INTENR_INTEN               BIT(0)

#define RCAR_GYROADC_SAMPLE_RATE                800     /* Hz */

#define RCAR_GYROADC_RUNTIME_PM_DELAY_MS        2000

enum rcar_gyroadc_model {
        RCAR_GYROADC_MODEL_DEFAULT,
        RCAR_GYROADC_MODEL_R8A7792,
};

struct rcar_gyroadc {
        struct device                   *dev;
        void __iomem                    *regs;
        struct clk                      *clk;
        struct regulator                *vref[8];
        unsigned int                    num_channels;
        enum rcar_gyroadc_model         model;
        unsigned int                    mode;
        unsigned int                    sample_width;
};

static void rcar_gyroadc_hw_init(struct rcar_gyroadc *priv)
{
        const unsigned long clk_mhz = clk_get_rate(priv->clk) / 1000000;
        const unsigned long clk_mul =
                (priv->mode == RCAR_GYROADC_MODE_SELECT_1_MB88101A) ? 10 : 5;
        unsigned long clk_len = clk_mhz * clk_mul;

        /*
         * According to the R-Car Gen2 datasheet Rev. 1.01, Sept 08 2014,
         * page 77-7, clock length must be even number. If it's odd number,
         * add one.
         */
        if (clk_len & 1)
                clk_len++;

        /* Stop the GyroADC. */
        writel(0, priv->regs + RCAR_GYROADC_START_STOP);

        /* Disable IRQ on V2H. */
        if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
                writel(0, priv->regs + RCAR_GYROADC_INTENR);

        /* Set mode and timing. */
        writel(priv->mode, priv->regs + RCAR_GYROADC_MODE_SELECT);
        writel(clk_len, priv->regs + RCAR_GYROADC_CLOCK_LENGTH);
        writel(clk_mhz * 1250, priv->regs + RCAR_GYROADC_1_25MS_LENGTH);
}

static void rcar_gyroadc_hw_start(struct rcar_gyroadc *priv)
{
        /* Start sampling. */
        writel(RCAR_GYROADC_START_STOP_START,
               priv->regs + RCAR_GYROADC_START_STOP);

        /*
         * Wait for the first conversion to complete. This is longer than
         * the 1.25 mS in the datasheet because 1.25 mS is not enough for
         * the hardware to deliver the first sample and the hardware does
         * then return zeroes instead of valid data.
         */
        mdelay(3);
}

static void rcar_gyroadc_hw_stop(struct rcar_gyroadc *priv)
{
        /* Stop the GyroADC. */
        writel(0, priv->regs + RCAR_GYROADC_START_STOP);
}

#define RCAR_GYROADC_CHAN(_idx) {                               \
        .type                   = IIO_VOLTAGE,                  \
        .indexed                = 1,                            \
        .channel                = (_idx),                       \
        .info_mask_separate     = BIT(IIO_CHAN_INFO_RAW) |      \
                                  BIT(IIO_CHAN_INFO_SCALE),     \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
}

static const struct iio_chan_spec rcar_gyroadc_iio_channels_1[] = {
        RCAR_GYROADC_CHAN(0),
        RCAR_GYROADC_CHAN(1),
        RCAR_GYROADC_CHAN(2),
        RCAR_GYROADC_CHAN(3),
};

static const struct iio_chan_spec rcar_gyroadc_iio_channels_2[] = {
        RCAR_GYROADC_CHAN(0),
        RCAR_GYROADC_CHAN(1),
        RCAR_GYROADC_CHAN(2),
        RCAR_GYROADC_CHAN(3),
        RCAR_GYROADC_CHAN(4),
        RCAR_GYROADC_CHAN(5),
        RCAR_GYROADC_CHAN(6),
        RCAR_GYROADC_CHAN(7),
};

static const struct iio_chan_spec rcar_gyroadc_iio_channels_3[] = {
        RCAR_GYROADC_CHAN(0),
        RCAR_GYROADC_CHAN(1),
        RCAR_GYROADC_CHAN(2),
        RCAR_GYROADC_CHAN(3),
        RCAR_GYROADC_CHAN(4),
        RCAR_GYROADC_CHAN(5),
        RCAR_GYROADC_CHAN(6),
        RCAR_GYROADC_CHAN(7),
};

static int rcar_gyroadc_set_power(struct rcar_gyroadc *priv, bool on)
{
        struct device *dev = priv->dev;

        if (on)
                return pm_runtime_resume_and_get(dev);

        return pm_runtime_put_autosuspend(dev);
}

static int rcar_gyroadc_read_raw(struct iio_dev *indio_dev,
                                 struct iio_chan_spec const *chan,
                                 int *val, int *val2, long mask)
{
        struct rcar_gyroadc *priv = iio_priv(indio_dev);
        struct regulator *consumer;
        unsigned int datareg = RCAR_GYROADC_REALTIME_DATA(chan->channel);
        unsigned int vref;
        int ret;

        /*
         * MB88101 is special in that it has only single regulator for
         * all four channels.
         */
        if (priv->mode == RCAR_GYROADC_MODE_SELECT_1_MB88101A)
                consumer = priv->vref[0];
        else
                consumer = priv->vref[chan->channel];

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                if (chan->type != IIO_VOLTAGE)
                        return -EINVAL;

                /* Channel not connected. */
                if (!consumer)
                        return -EINVAL;

                if (!iio_device_claim_direct(indio_dev))
                        return -EBUSY;

                ret = rcar_gyroadc_set_power(priv, true);
                if (ret < 0) {
                        iio_device_release_direct(indio_dev);
                        return ret;
                }

                *val = readl(priv->regs + datareg);
                *val &= BIT(priv->sample_width) - 1;

                ret = rcar_gyroadc_set_power(priv, false);
                iio_device_release_direct(indio_dev);
                if (ret < 0)
                        return ret;

                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                /* Channel not connected. */
                if (!consumer)
                        return -EINVAL;

                vref = regulator_get_voltage(consumer);
                *val = vref / 1000;
                *val2 = 1 << priv->sample_width;

                return IIO_VAL_FRACTIONAL;
        case IIO_CHAN_INFO_SAMP_FREQ:
                *val = RCAR_GYROADC_SAMPLE_RATE;

                return IIO_VAL_INT;
        default:
                return -EINVAL;
        }
}

static int rcar_gyroadc_reg_access(struct iio_dev *indio_dev,
                                   unsigned int reg, unsigned int writeval,
                                   unsigned int *readval)
{
        struct rcar_gyroadc *priv = iio_priv(indio_dev);
        unsigned int maxreg = RCAR_GYROADC_FIFO_STATUS;

        if (readval == NULL)
                return -EINVAL;

        if (reg % 4)
                return -EINVAL;

        /* Handle the V2H case with extra interrupt block. */
        if (priv->model == RCAR_GYROADC_MODEL_R8A7792)
                maxreg = RCAR_GYROADC_INTENR;

        if (reg > maxreg)
                return -EINVAL;

        *readval = readl(priv->regs + reg);

        return 0;
}

static const struct iio_info rcar_gyroadc_iio_info = {
        .read_raw               = rcar_gyroadc_read_raw,
        .debugfs_reg_access     = rcar_gyroadc_reg_access,
};

static const struct of_device_id rcar_gyroadc_match[] = {
        {
                /* R-Car compatible GyroADC */
                .compatible     = "renesas,rcar-gyroadc",
                .data           = (void *)RCAR_GYROADC_MODEL_DEFAULT,
        }, {
                /* R-Car V2H specialty with interrupt registers. */
                .compatible     = "renesas,r8a7792-gyroadc",
                .data           = (void *)RCAR_GYROADC_MODEL_R8A7792,
        }, {
                /* sentinel */
        }
};

MODULE_DEVICE_TABLE(of, rcar_gyroadc_match);

static const struct of_device_id rcar_gyroadc_child_match[] __maybe_unused = {
        /* Mode 1 ADCs */
        {
                .compatible     = "fujitsu,mb88101a",
                .data           = (void *)RCAR_GYROADC_MODE_SELECT_1_MB88101A,
        },
        /* Mode 2 ADCs */
        {
                .compatible     = "ti,adcs7476",
                .data           = (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
        }, {
                .compatible     = "ti,adc121",
                .data           = (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
        }, {
                .compatible     = "adi,ad7476",
                .data           = (void *)RCAR_GYROADC_MODE_SELECT_2_ADCS7476,
        },
        /* Mode 3 ADCs */
        {
                .compatible     = "maxim,max1162",
                .data           = (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
        }, {
                .compatible     = "maxim,max11100",
                .data           = (void *)RCAR_GYROADC_MODE_SELECT_3_MAX1162,
        },
        { }
};

static int rcar_gyroadc_parse_subdevs(struct iio_dev *indio_dev)
{
        const struct of_device_id *of_id;
        const struct iio_chan_spec *channels;
        struct rcar_gyroadc *priv = iio_priv(indio_dev);
        struct device *dev = priv->dev;
        struct device_node *np = dev->of_node;
        struct regulator *vref;
        unsigned int reg;
        unsigned int adcmode = -1, childmode;
        unsigned int sample_width;
        unsigned int num_channels;
        int ret, first = 1;

        for_each_available_child_of_node_scoped(np, child) {
                of_id = of_match_node(rcar_gyroadc_child_match, child);
                if (!of_id) {
                        dev_err(dev, "Ignoring unsupported ADC \"%pOFn\".",
                                child);
                        continue;
                }

                childmode = (uintptr_t)of_id->data;
                switch (childmode) {
                case RCAR_GYROADC_MODE_SELECT_1_MB88101A:
                        sample_width = 12;
                        channels = rcar_gyroadc_iio_channels_1;
                        num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_1);
                        break;
                case RCAR_GYROADC_MODE_SELECT_2_ADCS7476:
                        sample_width = 15;
                        channels = rcar_gyroadc_iio_channels_2;
                        num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_2);
                        break;
                case RCAR_GYROADC_MODE_SELECT_3_MAX1162:
                        sample_width = 16;
                        channels = rcar_gyroadc_iio_channels_3;
                        num_channels = ARRAY_SIZE(rcar_gyroadc_iio_channels_3);
                        break;
                default:
                        return -EINVAL;
                }

                /*
                 * MB88101 is special in that it's only a single chip taking
                 * up all the CHS lines. Thus, the DT binding is also special
                 * and has no reg property. If we run into such ADC, handle
                 * it here.
                 */
                if (childmode == RCAR_GYROADC_MODE_SELECT_1_MB88101A) {
                        reg = 0;
                } else {
                        ret = of_property_read_u32(child, "reg", &reg);
                        if (ret) {
                                dev_err(dev,
                                        "Failed to get child reg property of ADC \"%pOFn\".\n",
                                        child);
                                return ret;
                        }

                        /* Channel number is too high. */
                        if (reg >= num_channels) {
                                dev_err(dev,
                                        "Only %i channels supported with %pOFn, but reg = <%i>.\n",
                                        num_channels, child, reg);
                                return -EINVAL;
                        }
                }

                /* Child node selected different mode than the rest. */
                if (!first && (adcmode != childmode)) {
                        dev_err(dev,
                                "Channel %i uses different ADC mode than the rest.\n",
                                reg);
                        return -EINVAL;
                }

                /* Channel is valid, grab the regulator. */
                dev->of_node = child;
                vref = devm_regulator_get(dev, "vref");
                dev->of_node = np;
                if (IS_ERR(vref)) {
                        dev_dbg(dev, "Channel %i 'vref' supply not connected.\n",
                                reg);
                        return PTR_ERR(vref);
                }

                priv->vref[reg] = vref;

                if (!first)
                        continue;

                /* First child node which passed sanity tests. */
                adcmode = childmode;
                first = 0;

                priv->num_channels = num_channels;
                priv->mode = childmode;
                priv->sample_width = sample_width;

                indio_dev->channels = channels;
                indio_dev->num_channels = num_channels;

                /*
                 * MB88101 is special and we only have one such device
                 * attached to the GyroADC at a time, so if we found it,
                 * we can stop parsing here.
                 */
                if (childmode == RCAR_GYROADC_MODE_SELECT_1_MB88101A) {
                        break;
                }
        }

        if (first) {
                dev_err(dev, "No valid ADC channels found, aborting.\n");
                return -EINVAL;
        }

        return 0;
}

static void rcar_gyroadc_deinit_supplies(struct iio_dev *indio_dev)
{
        struct rcar_gyroadc *priv = iio_priv(indio_dev);
        unsigned int i;

        for (i = 0; i < priv->num_channels; i++) {
                if (!priv->vref[i])
                        continue;

                regulator_disable(priv->vref[i]);
        }
}

static int rcar_gyroadc_init_supplies(struct iio_dev *indio_dev)
{
        struct rcar_gyroadc *priv = iio_priv(indio_dev);
        struct device *dev = priv->dev;
        unsigned int i;
        int ret;

        for (i = 0; i < priv->num_channels; i++) {
                if (!priv->vref[i])
                        continue;

                ret = regulator_enable(priv->vref[i]);
                if (ret) {
                        dev_err(dev, "Failed to enable regulator %i (ret=%i)\n",
                                i, ret);
                        goto err;
                }
        }

        return 0;

err:
        rcar_gyroadc_deinit_supplies(indio_dev);
        return ret;
}

static int rcar_gyroadc_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct rcar_gyroadc *priv;
        struct iio_dev *indio_dev;
        int ret;

        indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
        if (!indio_dev)
                return -ENOMEM;

        priv = iio_priv(indio_dev);
        priv->dev = dev;

        priv->regs = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(priv->regs))
                return PTR_ERR(priv->regs);

        priv->clk = devm_clk_get(dev, "fck");
        if (IS_ERR(priv->clk))
                return dev_err_probe(dev, PTR_ERR(priv->clk),
                                     "Failed to get IF clock\n");

        ret = rcar_gyroadc_parse_subdevs(indio_dev);
        if (ret)
                return ret;

        ret = rcar_gyroadc_init_supplies(indio_dev);
        if (ret)
                return ret;

        priv->model = (uintptr_t)of_device_get_match_data(&pdev->dev);

        platform_set_drvdata(pdev, indio_dev);

        indio_dev->name = DRIVER_NAME;
        indio_dev->info = &rcar_gyroadc_iio_info;
        indio_dev->modes = INDIO_DIRECT_MODE;

        ret = clk_prepare_enable(priv->clk);
        if (ret) {
                dev_err(dev, "Could not prepare or enable the IF clock.\n");
                goto err_clk_if_enable;
        }

        pm_runtime_set_autosuspend_delay(dev, RCAR_GYROADC_RUNTIME_PM_DELAY_MS);
        pm_runtime_use_autosuspend(dev);
        pm_runtime_enable(dev);

        ret = pm_runtime_resume_and_get(dev);
        if (ret)
                goto err_power_up;

        rcar_gyroadc_hw_init(priv);
        rcar_gyroadc_hw_start(priv);

        ret = iio_device_register(indio_dev);
        if (ret) {
                dev_err(dev, "Couldn't register IIO device.\n");
                goto err_iio_device_register;
        }

        pm_runtime_put_sync(dev);

        return 0;

err_iio_device_register:
        rcar_gyroadc_hw_stop(priv);
        pm_runtime_put_sync(dev);
err_power_up:
        pm_runtime_disable(dev);
        pm_runtime_set_suspended(dev);
        clk_disable_unprepare(priv->clk);
err_clk_if_enable:
        rcar_gyroadc_deinit_supplies(indio_dev);

        return ret;
}

static void rcar_gyroadc_remove(struct platform_device *pdev)
{
        struct iio_dev *indio_dev = platform_get_drvdata(pdev);
        struct rcar_gyroadc *priv = iio_priv(indio_dev);
        struct device *dev = priv->dev;

        iio_device_unregister(indio_dev);
        pm_runtime_get_sync(dev);
        rcar_gyroadc_hw_stop(priv);
        pm_runtime_put_sync(dev);
        pm_runtime_disable(dev);
        pm_runtime_set_suspended(dev);
        clk_disable_unprepare(priv->clk);
        rcar_gyroadc_deinit_supplies(indio_dev);
}

static int rcar_gyroadc_suspend(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);
        struct rcar_gyroadc *priv = iio_priv(indio_dev);

        rcar_gyroadc_hw_stop(priv);

        return 0;
}

static int rcar_gyroadc_resume(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);
        struct rcar_gyroadc *priv = iio_priv(indio_dev);

        rcar_gyroadc_hw_start(priv);

        return 0;
}

static const struct dev_pm_ops rcar_gyroadc_pm_ops = {
        RUNTIME_PM_OPS(rcar_gyroadc_suspend, rcar_gyroadc_resume, NULL)
};

static struct platform_driver rcar_gyroadc_driver = {
        .probe          = rcar_gyroadc_probe,
        .remove         = rcar_gyroadc_remove,
        .driver         = {
                .name           = DRIVER_NAME,
                .of_match_table = rcar_gyroadc_match,
                .pm             = pm_ptr(&rcar_gyroadc_pm_ops),
        },
};

module_platform_driver(rcar_gyroadc_driver);

MODULE_AUTHOR("Marek Vasut <marek.vasut@gmail.com>");
MODULE_DESCRIPTION("Renesas R-Car GyroADC driver");
MODULE_LICENSE("GPL");