/*
 * TI ADC MFD driver
 *
 * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation version 2.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/iio/iio.h>

#include <linux/mfd/ti_am335x_tscadc.h>
#include <linux/platform_data/ti_am335x_adc.h>

struct tiadc_device {
        struct ti_tscadc_dev *mfd_tscadc;
        int channels;
};

static unsigned int tiadc_readl(struct tiadc_device *adc, unsigned int reg)
{
        return readl(adc->mfd_tscadc->tscadc_base + reg);
}

static void tiadc_writel(struct tiadc_device *adc, unsigned int reg,
                                        unsigned int val)
{
        writel(val, adc->mfd_tscadc->tscadc_base + reg);
}

static void tiadc_step_config(struct tiadc_device *adc_dev)
{
        unsigned int stepconfig;
        int i, channels = 0, steps;

        /*
         * There are 16 configurable steps and 8 analog input
         * lines available which are shared between Touchscreen and ADC.
         *
         * Steps backwards i.e. from 16 towards 0 are used by ADC
         * depending on number of input lines needed.
         * Channel would represent which analog input
         * needs to be given to ADC to digitalize data.
         */

        steps = TOTAL_STEPS - adc_dev->channels;
        channels = TOTAL_CHANNELS - adc_dev->channels;

        stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1;

        for (i = (steps + 1); i <= TOTAL_STEPS; i++) {
                tiadc_writel(adc_dev, REG_STEPCONFIG(i),
                                stepconfig | STEPCONFIG_INP(channels));
                tiadc_writel(adc_dev, REG_STEPDELAY(i),
                                STEPCONFIG_OPENDLY);
                channels++;
        }
        tiadc_writel(adc_dev, REG_SE, STPENB_STEPENB);
}

static int tiadc_channel_init(struct iio_dev *indio_dev, int channels)
{
        struct iio_chan_spec *chan_array;
        int i;

        indio_dev->num_channels = channels;
        chan_array = kcalloc(indio_dev->num_channels,
                        sizeof(struct iio_chan_spec), GFP_KERNEL);

        if (chan_array == NULL)
                return -ENOMEM;

        for (i = 0; i < (indio_dev->num_channels); i++) {
                struct iio_chan_spec *chan = chan_array + i;
                chan->type = IIO_VOLTAGE;
                chan->indexed = 1;
                chan->channel = i;
                chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
        }

        indio_dev->channels = chan_array;

        return indio_dev->num_channels;
}

static void tiadc_channels_remove(struct iio_dev *indio_dev)
{
        kfree(indio_dev->channels);
}

static int tiadc_read_raw(struct iio_dev *indio_dev,
                struct iio_chan_spec const *chan,
                int *val, int *val2, long mask)
{
        struct tiadc_device *adc_dev = iio_priv(indio_dev);
        int i;
        unsigned int fifo1count, readx1;

        /*
         * When the sub-system is first enabled,
         * the sequencer will always start with the
         * lowest step (1) and continue until step (16).
         * For ex: If we have enabled 4 ADC channels and
         * currently use only 1 out of them, the
         * sequencer still configures all the 4 steps,
         * leading to 3 unwanted data.
         * Hence we need to flush out this data.
         */

        fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
        for (i = 0; i < fifo1count; i++) {
                readx1 = tiadc_readl(adc_dev, REG_FIFO1);
                if (i == chan->channel)
                        *val = readx1 & 0xfff;
        }
        tiadc_writel(adc_dev, REG_SE, STPENB_STEPENB);

        return IIO_VAL_INT;
}

static const struct iio_info tiadc_info = {
        .read_raw = &tiadc_read_raw,
};

static int tiadc_probe(struct platform_device *pdev)
{
        struct iio_dev          *indio_dev;
        struct tiadc_device     *adc_dev;
        struct ti_tscadc_dev    *tscadc_dev = pdev->dev.platform_data;
        struct mfd_tscadc_board *pdata;
        int                     err;

        pdata = tscadc_dev->dev->platform_data;
        if (!pdata || !pdata->adc_init) {
                dev_err(&pdev->dev, "Could not find platform data\n");
                return -EINVAL;
        }

        indio_dev = iio_device_alloc(sizeof(struct tiadc_device));
        if (indio_dev == NULL) {
                dev_err(&pdev->dev, "failed to allocate iio device\n");
                err = -ENOMEM;
                goto err_ret;
        }
        adc_dev = iio_priv(indio_dev);

        adc_dev->mfd_tscadc = tscadc_dev;
        adc_dev->channels = pdata->adc_init->adc_channels;

        indio_dev->dev.parent = &pdev->dev;
        indio_dev->name = dev_name(&pdev->dev);
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->info = &tiadc_info;

        tiadc_step_config(adc_dev);

        err = tiadc_channel_init(indio_dev, adc_dev->channels);
        if (err < 0)
                goto err_free_device;

        err = iio_device_register(indio_dev);
        if (err)
                goto err_free_channels;

        platform_set_drvdata(pdev, indio_dev);

        return 0;

err_free_channels:
        tiadc_channels_remove(indio_dev);
err_free_device:
        iio_device_free(indio_dev);
err_ret:
        return err;
}

static int tiadc_remove(struct platform_device *pdev)
{
        struct iio_dev *indio_dev = platform_get_drvdata(pdev);

        iio_device_unregister(indio_dev);
        tiadc_channels_remove(indio_dev);

        iio_device_free(indio_dev);

        return 0;
}

#ifdef CONFIG_PM
static int tiadc_suspend(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);
        struct tiadc_device *adc_dev = iio_priv(indio_dev);
        struct ti_tscadc_dev *tscadc_dev = dev->platform_data;
        unsigned int idle;

        if (!device_may_wakeup(tscadc_dev->dev)) {
                idle = tiadc_readl(adc_dev, REG_CTRL);
                idle &= ~(CNTRLREG_TSCSSENB);
                tiadc_writel(adc_dev, REG_CTRL, (idle |
                                CNTRLREG_POWERDOWN));
        }

        return 0;
}

static int tiadc_resume(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);
        struct tiadc_device *adc_dev = iio_priv(indio_dev);
        unsigned int restore;

        /* Make sure ADC is powered up */
        restore = tiadc_readl(adc_dev, REG_CTRL);
        restore &= ~(CNTRLREG_POWERDOWN);
        tiadc_writel(adc_dev, REG_CTRL, restore);

        tiadc_step_config(adc_dev);

        return 0;
}

static const struct dev_pm_ops tiadc_pm_ops = {
        .suspend = tiadc_suspend,
        .resume = tiadc_resume,
};
#define TIADC_PM_OPS (&tiadc_pm_ops)
#else
#define TIADC_PM_OPS NULL
#endif

static struct platform_driver tiadc_driver = {
        .driver = {
                .name   = "tiadc",
                .owner  = THIS_MODULE,
                .pm     = TIADC_PM_OPS,
        },
        .probe  = tiadc_probe,
        .remove = tiadc_remove,
};

module_platform_driver(tiadc_driver);

MODULE_DESCRIPTION("TI ADC controller driver");
MODULE_AUTHOR("Rachna Patil <rachna@ti.com>");
MODULE_LICENSE("GPL");