ad_sigma_delta.c

Go to the documentation of this file.

/*
 * Support code for Analog Devices Sigma-Delta ADCs
 *
 * Copyright 2012 Analog Devices Inc.
 *  Author: Lars-Peter Clausen <[email protected]>
 *
 * Licensed under the GPL-2.
 */

#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/err.h>
#include <linux/module.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/buffer.h>
#include <linux/iio/trigger.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/adc/ad_sigma_delta.h>

#include <asm/unaligned.h>


#define AD_SD_COMM_CHAN_MASK    0x3

#define AD_SD_REG_COMM      0x00
#define AD_SD_REG_DATA      0x03

void ad_sd_set_comm(struct ad_sigma_delta *sigma_delta, uint8_t comm)
{
    /* Some variants use the lower two bits of the communications register
     * to select the channel */
    sigma_delta->comm = comm & AD_SD_COMM_CHAN_MASK;
}
EXPORT_SYMBOL_GPL(ad_sd_set_comm);

int ad_sd_write_reg(struct ad_sigma_delta *sigma_delta, unsigned int reg,
    unsigned int size, unsigned int val)
{
    uint8_t *data = sigma_delta->data;
    struct spi_transfer t = {
        .tx_buf     = data,
        .len        = size + 1,
        .cs_change  = sigma_delta->bus_locked,
    };
    struct spi_message m;
    int ret;

    data[0] = (reg << sigma_delta->info->addr_shift) | sigma_delta->comm;

    switch (size) {
    case 3:
        data[1] = val >> 16;
        data[2] = val >> 8;
        data[3] = val;
        break;
    case 2:
        put_unaligned_be16(val, &data[1]);
        break;
    case 1:
        data[1] = val;
        break;
    case 0:
        break;
    default:
        return -EINVAL;
    }

    spi_message_init(&m);
    spi_message_add_tail(&t, &m);

    if (sigma_delta->bus_locked)
        ret = spi_sync_locked(sigma_delta->spi, &m);
    else
        ret = spi_sync(sigma_delta->spi, &m);

    return ret;
}
EXPORT_SYMBOL_GPL(ad_sd_write_reg);

static int ad_sd_read_reg_raw(struct ad_sigma_delta *sigma_delta,
    unsigned int reg, unsigned int size, uint8_t *val)
{
    uint8_t *data = sigma_delta->data;
    int ret;
    struct spi_transfer t[] = {
        {
            .tx_buf = data,
            .len = 1,
        }, {
            .rx_buf = val,
            .len = size,
            .cs_change = sigma_delta->bus_locked,
        },
    };
    struct spi_message m;

    spi_message_init(&m);

    if (sigma_delta->info->has_registers) {
        data[0] = reg << sigma_delta->info->addr_shift;
        data[0] |= sigma_delta->info->read_mask;
        spi_message_add_tail(&t[0], &m);
    }
    spi_message_add_tail(&t[1], &m);

    if (sigma_delta->bus_locked)
        ret = spi_sync_locked(sigma_delta->spi, &m);
    else
        ret = spi_sync(sigma_delta->spi, &m);

    return ret;
}

int ad_sd_read_reg(struct ad_sigma_delta *sigma_delta,
    unsigned int reg, unsigned int size, unsigned int *val)
{
    int ret;

    ret = ad_sd_read_reg_raw(sigma_delta, reg, size, sigma_delta->data);
    if (ret < 0)
        goto out;

    switch (size) {
    case 4:
        *val = get_unaligned_be32(sigma_delta->data);
        break;
    case 3:
        *val = (sigma_delta->data[0] << 16) |
            (sigma_delta->data[1] << 8) |
            sigma_delta->data[2];
        break;
    case 2:
        *val = get_unaligned_be16(sigma_delta->data);
        break;
    case 1:
        *val = sigma_delta->data[0];
        break;
    default:
        ret = -EINVAL;
        break;
    }

out:
    return ret;
}
EXPORT_SYMBOL_GPL(ad_sd_read_reg);

static int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
    unsigned int mode, unsigned int channel)
{
    int ret;

    ret = ad_sigma_delta_set_channel(sigma_delta, channel);
    if (ret)
        return ret;

    spi_bus_lock(sigma_delta->spi->master);
    sigma_delta->bus_locked = true;
    INIT_COMPLETION(sigma_delta->completion);

    ret = ad_sigma_delta_set_mode(sigma_delta, mode);
    if (ret < 0)
        goto out;

    sigma_delta->irq_dis = false;
    enable_irq(sigma_delta->spi->irq);
    ret = wait_for_completion_timeout(&sigma_delta->completion, 2*HZ);
    if (ret == 0) {
        sigma_delta->irq_dis = true;
        disable_irq_nosync(sigma_delta->spi->irq);
        ret = -EIO;
    } else {
        ret = 0;
    }
out:
    sigma_delta->bus_locked = false;
    spi_bus_unlock(sigma_delta->spi->master);
    ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);

    return ret;
}

int ad_sd_calibrate_all(struct ad_sigma_delta *sigma_delta,
    const struct ad_sd_calib_data *cb, unsigned int n)
{
    unsigned int i;
    int ret;

    for (i = 0; i < n; i++) {
        ret = ad_sd_calibrate(sigma_delta, cb[i].mode, cb[i].channel);
        if (ret)
            return ret;
    }

    return 0;
}
EXPORT_SYMBOL_GPL(ad_sd_calibrate_all);

int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
    const struct iio_chan_spec *chan, int *val)
{
    struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
    unsigned int sample, raw_sample;
    int ret = 0;

    if (iio_buffer_enabled(indio_dev))
        return -EBUSY;

    mutex_lock(&indio_dev->mlock);
    ad_sigma_delta_set_channel(sigma_delta, chan->address);

    spi_bus_lock(sigma_delta->spi->master);
    sigma_delta->bus_locked = true;
    INIT_COMPLETION(sigma_delta->completion);

    ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_SINGLE);

    sigma_delta->irq_dis = false;
    enable_irq(sigma_delta->spi->irq);
    ret = wait_for_completion_interruptible_timeout(
            &sigma_delta->completion, HZ);

    sigma_delta->bus_locked = false;
    spi_bus_unlock(sigma_delta->spi->master);

    if (ret == 0)
        ret = -EIO;
    if (ret < 0)
        goto out;

    ret = ad_sd_read_reg(sigma_delta, AD_SD_REG_DATA,
        DIV_ROUND_UP(chan->scan_type.realbits + chan->scan_type.shift, 8),
        &raw_sample);

out:
    if (!sigma_delta->irq_dis) {
        disable_irq_nosync(sigma_delta->spi->irq);
        sigma_delta->irq_dis = true;
    }

    ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
    mutex_unlock(&indio_dev->mlock);

    if (ret)
        return ret;

    sample = raw_sample >> chan->scan_type.shift;
    sample &= (1 << chan->scan_type.realbits) - 1;
    *val = sample;

    ret = ad_sigma_delta_postprocess_sample(sigma_delta, raw_sample);
    if (ret)
        return ret;

    return IIO_VAL_INT;
}
EXPORT_SYMBOL_GPL(ad_sigma_delta_single_conversion);

static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
{
    struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
    unsigned int channel;
    int ret;

    ret = iio_triggered_buffer_postenable(indio_dev);
    if (ret < 0)
        return ret;

    channel = find_first_bit(indio_dev->active_scan_mask,
                 indio_dev->masklength);
    ret = ad_sigma_delta_set_channel(sigma_delta,
        indio_dev->channels[channel].address);
    if (ret)
        goto err_predisable;

    spi_bus_lock(sigma_delta->spi->master);
    sigma_delta->bus_locked = true;
    ret = ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_CONTINUOUS);
    if (ret)
        goto err_unlock;

    sigma_delta->irq_dis = false;
    enable_irq(sigma_delta->spi->irq);

    return 0;

err_unlock:
    spi_bus_unlock(sigma_delta->spi->master);
err_predisable:

    return ret;
}

static int ad_sd_buffer_postdisable(struct iio_dev *indio_dev)
{
    struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);

    INIT_COMPLETION(sigma_delta->completion);
    wait_for_completion_timeout(&sigma_delta->completion, HZ);

    if (!sigma_delta->irq_dis) {
        disable_irq_nosync(sigma_delta->spi->irq);
        sigma_delta->irq_dis = true;
    }

    ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);

    sigma_delta->bus_locked = false;
    return spi_bus_unlock(sigma_delta->spi->master);
}

static irqreturn_t ad_sd_trigger_handler(int irq, void *p)
{
    struct iio_poll_func *pf = p;
    struct iio_dev *indio_dev = pf->indio_dev;
    struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
    unsigned int reg_size;
    uint8_t data[16];
    int ret;

    memset(data, 0x00, 16);

    /* Guaranteed to be aligned with 8 byte boundary */
    if (indio_dev->scan_timestamp)
        ((s64 *)data)[1] = pf->timestamp;

    reg_size = indio_dev->channels[0].scan_type.realbits +
            indio_dev->channels[0].scan_type.shift;
    reg_size = DIV_ROUND_UP(reg_size, 8);

    switch (reg_size) {
    case 4:
    case 2:
    case 1:
        ret = ad_sd_read_reg_raw(sigma_delta, AD_SD_REG_DATA,
            reg_size, &data[0]);
        break;
    case 3:
        /* We store 24 bit samples in a 32 bit word. Keep the upper
         * byte set to zero. */
        ret = ad_sd_read_reg_raw(sigma_delta, AD_SD_REG_DATA,
            reg_size, &data[1]);
        break;
    }

    iio_push_to_buffer(indio_dev->buffer, (uint8_t *)data);

    iio_trigger_notify_done(indio_dev->trig);
    sigma_delta->irq_dis = false;
    enable_irq(sigma_delta->spi->irq);

    return IRQ_HANDLED;
}

static const struct iio_buffer_setup_ops ad_sd_buffer_setup_ops = {
    .preenable = &iio_sw_buffer_preenable,
    .postenable = &ad_sd_buffer_postenable,
    .predisable = &iio_triggered_buffer_predisable,
    .postdisable = &ad_sd_buffer_postdisable,
    .validate_scan_mask = &iio_validate_scan_mask_onehot,
};

static irqreturn_t ad_sd_data_rdy_trig_poll(int irq, void *private)
{
    struct ad_sigma_delta *sigma_delta = private;

    complete(&sigma_delta->completion);
    disable_irq_nosync(irq);
    sigma_delta->irq_dis = true;
    iio_trigger_poll(sigma_delta->trig, iio_get_time_ns());

    return IRQ_HANDLED;
}

int ad_sd_validate_trigger(struct iio_dev *indio_dev, struct iio_trigger *trig)
{
    struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);

    if (sigma_delta->trig != trig)
        return -EINVAL;

    return 0;
}
EXPORT_SYMBOL_GPL(ad_sd_validate_trigger);

static const struct iio_trigger_ops ad_sd_trigger_ops = {
    .owner = THIS_MODULE,
};

static int ad_sd_probe_trigger(struct iio_dev *indio_dev)
{
    struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
    int ret;

    sigma_delta->trig = iio_trigger_alloc("%s-dev%d", indio_dev->name,
                        indio_dev->id);
    if (sigma_delta->trig == NULL) {
        ret = -ENOMEM;
        goto error_ret;
    }
    sigma_delta->trig->ops = &ad_sd_trigger_ops;
    init_completion(&sigma_delta->completion);

    ret = request_irq(sigma_delta->spi->irq,
              ad_sd_data_rdy_trig_poll,
              IRQF_TRIGGER_LOW,
              indio_dev->name,
              sigma_delta);
    if (ret)
        goto error_free_trig;

    if (!sigma_delta->irq_dis) {
        sigma_delta->irq_dis = true;
        disable_irq_nosync(sigma_delta->spi->irq);
    }
    sigma_delta->trig->dev.parent = &sigma_delta->spi->dev;
    sigma_delta->trig->private_data = sigma_delta;

    ret = iio_trigger_register(sigma_delta->trig);
    if (ret)
        goto error_free_irq;

    /* select default trigger */
    indio_dev->trig = sigma_delta->trig;

    return 0;

error_free_irq:
    free_irq(sigma_delta->spi->irq, sigma_delta);
error_free_trig:
    iio_trigger_free(sigma_delta->trig);
error_ret:
    return ret;
}

static void ad_sd_remove_trigger(struct iio_dev *indio_dev)
{
    struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);

    iio_trigger_unregister(sigma_delta->trig);
    free_irq(sigma_delta->spi->irq, sigma_delta);
    iio_trigger_free(sigma_delta->trig);
}

int ad_sd_setup_buffer_and_trigger(struct iio_dev *indio_dev)
{
    int ret;

    ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
            &ad_sd_trigger_handler, &ad_sd_buffer_setup_ops);
    if (ret)
        return ret;

    ret = ad_sd_probe_trigger(indio_dev);
    if (ret) {
        iio_triggered_buffer_cleanup(indio_dev);
        return ret;
    }

    return 0;
}
EXPORT_SYMBOL_GPL(ad_sd_setup_buffer_and_trigger);

void ad_sd_cleanup_buffer_and_trigger(struct iio_dev *indio_dev)
{
    ad_sd_remove_trigger(indio_dev);
    iio_triggered_buffer_cleanup(indio_dev);
}
EXPORT_SYMBOL_GPL(ad_sd_cleanup_buffer_and_trigger);

int ad_sd_init(struct ad_sigma_delta *sigma_delta, struct iio_dev *indio_dev,
    struct spi_device *spi, const struct ad_sigma_delta_info *info)
{
    sigma_delta->spi = spi;
    sigma_delta->info = info;
    iio_device_set_drvdata(indio_dev, sigma_delta);

    return 0;
}
EXPORT_SYMBOL_GPL(ad_sd_init);

MODULE_AUTHOR("Lars-Peter Clausen <[email protected]>");
MODULE_DESCRIPTION("Analog Devices Sigma-Delta ADCs");
MODULE_LICENSE("GPL v2");