lpc32xx_adc.c

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/*
 *  lpc32xx_adc.c - Support for ADC in LPC32XX
 *
 *  3-channel, 10-bit ADC
 *
 *  Copyright (C) 2011, 2012 Roland Stigge <[email protected]>
 *
 *  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; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/completion.h>
#include <linux/of.h>

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

/*
 * LPC32XX registers definitions
 */
#define LPC32XX_ADC_SELECT(x)   ((x) + 0x04)
#define LPC32XX_ADC_CTRL(x) ((x) + 0x08)
#define LPC32XX_ADC_VALUE(x)    ((x) + 0x48)

/* Bit definitions for LPC32XX_ADC_SELECT: */
#define AD_REFm         0x00000200 /* constant, always write this value! */
#define AD_REFp     0x00000080 /* constant, always write this value! */
#define AD_IN       0x00000010 /* multiple of this is the */
                   /* channel number: 0, 1, 2 */
#define AD_INTERNAL 0x00000004 /* constant, always write this value! */

/* Bit definitions for LPC32XX_ADC_CTRL: */
#define AD_STROBE   0x00000002
#define AD_PDN_CTRL 0x00000004

/* Bit definitions for LPC32XX_ADC_VALUE: */
#define ADC_VALUE_MASK  0x000003FF

#define MOD_NAME "lpc32xx-adc"

struct lpc32xx_adc_info {
    void __iomem *adc_base;
    struct clk *clk;
    struct completion completion;

    u32 value;
};

static int lpc32xx_read_raw(struct iio_dev *indio_dev,
                struct iio_chan_spec const *chan,
                int *val,
                int *val2,
                long mask)
{
    struct lpc32xx_adc_info *info = iio_priv(indio_dev);

    if (mask == IIO_CHAN_INFO_RAW) {
        mutex_lock(&indio_dev->mlock);
        clk_enable(info->clk);
        /* Measurement setup */
        __raw_writel(AD_INTERNAL | (chan->address) | AD_REFp | AD_REFm,
            LPC32XX_ADC_SELECT(info->adc_base));
        /* Trigger conversion */
        __raw_writel(AD_PDN_CTRL | AD_STROBE,
            LPC32XX_ADC_CTRL(info->adc_base));
        wait_for_completion(&info->completion); /* set by ISR */
        clk_disable(info->clk);
        *val = info->value;
        mutex_unlock(&indio_dev->mlock);

        return IIO_VAL_INT;
    }

    return -EINVAL;
}

static const struct iio_info lpc32xx_adc_iio_info = {
    .read_raw = &lpc32xx_read_raw,
    .driver_module = THIS_MODULE,
};

#define LPC32XX_ADC_CHANNEL(_index) {           \
    .type = IIO_VOLTAGE,                \
    .indexed = 1,                   \
    .channel = _index,              \
    .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT,    \
    .address = AD_IN * _index,          \
    .scan_index = _index,               \
}

static const struct iio_chan_spec lpc32xx_adc_iio_channels[] = {
    LPC32XX_ADC_CHANNEL(0),
    LPC32XX_ADC_CHANNEL(1),
    LPC32XX_ADC_CHANNEL(2),
};

static irqreturn_t lpc32xx_adc_isr(int irq, void *dev_id)
{
    struct lpc32xx_adc_info *info = (struct lpc32xx_adc_info *) dev_id;

    /* Read value and clear irq */
    info->value = __raw_readl(LPC32XX_ADC_VALUE(info->adc_base)) &
                ADC_VALUE_MASK;
    complete(&info->completion);

    return IRQ_HANDLED;
}

static int __devinit lpc32xx_adc_probe(struct platform_device *pdev)
{
    struct lpc32xx_adc_info *info = NULL;
    struct resource *res;
    int retval = -ENODEV;
    struct iio_dev *iodev = NULL;
    int irq;

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!res) {
        dev_err(&pdev->dev, "failed to get platform I/O memory\n");
        retval = -EBUSY;
        goto errout1;
    }

    iodev = iio_device_alloc(sizeof(struct lpc32xx_adc_info));
    if (!iodev) {
        dev_err(&pdev->dev, "failed allocating iio device\n");
        retval = -ENOMEM;
        goto errout1;
    }

    info = iio_priv(iodev);

    info->adc_base = ioremap(res->start, res->end - res->start + 1);
    if (!info->adc_base) {
        dev_err(&pdev->dev, "failed mapping memory\n");
        retval = -EBUSY;
        goto errout2;
    }

    info->clk = clk_get(&pdev->dev, NULL);
    if (IS_ERR(info->clk)) {
        dev_err(&pdev->dev, "failed getting clock\n");
        goto errout3;
    }

    irq = platform_get_irq(pdev, 0);
    if ((irq < 0) || (irq >= NR_IRQS)) {
        dev_err(&pdev->dev, "failed getting interrupt resource\n");
        retval = -EINVAL;
        goto errout4;
    }

    retval = request_irq(irq, lpc32xx_adc_isr, 0, MOD_NAME, info);
    if (retval < 0) {
        dev_err(&pdev->dev, "failed requesting interrupt\n");
        goto errout4;
    }

    platform_set_drvdata(pdev, iodev);

    init_completion(&info->completion);

    iodev->name = MOD_NAME;
    iodev->dev.parent = &pdev->dev;
    iodev->info = &lpc32xx_adc_iio_info;
    iodev->modes = INDIO_DIRECT_MODE;
    iodev->channels = lpc32xx_adc_iio_channels;
    iodev->num_channels = ARRAY_SIZE(lpc32xx_adc_iio_channels);

    retval = iio_device_register(iodev);
    if (retval)
        goto errout5;

    dev_info(&pdev->dev, "LPC32XX ADC driver loaded, IRQ %d\n", irq);

    return 0;

errout5:
    free_irq(irq, info);
errout4:
    clk_put(info->clk);
errout3:
    iounmap(info->adc_base);
errout2:
    iio_device_free(iodev);
errout1:
    return retval;
}

static int __devexit lpc32xx_adc_remove(struct platform_device *pdev)
{
    struct iio_dev *iodev = platform_get_drvdata(pdev);
    struct lpc32xx_adc_info *info = iio_priv(iodev);
    int irq = platform_get_irq(pdev, 0);

    iio_device_unregister(iodev);
    free_irq(irq, info);
    platform_set_drvdata(pdev, NULL);
    clk_put(info->clk);
    iounmap(info->adc_base);
    iio_device_free(iodev);

    return 0;
}

#ifdef CONFIG_OF
static const struct of_device_id lpc32xx_adc_match[] = {
    { .compatible = "nxp,lpc3220-adc" },
    {},
};
MODULE_DEVICE_TABLE(of, lpc32xx_adc_match);
#endif

static struct platform_driver lpc32xx_adc_driver = {
    .probe      = lpc32xx_adc_probe,
    .remove     = __devexit_p(lpc32xx_adc_remove),
    .driver     = {
        .name   = MOD_NAME,
        .owner  = THIS_MODULE,
        .of_match_table = of_match_ptr(lpc32xx_adc_match),
    },
};

module_platform_driver(lpc32xx_adc_driver);

MODULE_AUTHOR("Roland Stigge <[email protected]>");
MODULE_DESCRIPTION("LPC32XX ADC driver");
MODULE_LICENSE("GPL");