// SPDX-License-Identifier: GPL-2.0-only
/* The industrial I/O callback buffer
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/iio/iio.h>
#include <linux/iio/buffer_impl.h>
#include <linux/iio/consumer.h>

struct iio_cb_buffer {
        struct iio_buffer buffer;
        /* Must be safe to call from any context (e.g. must not sleep). */
        int (*cb)(const void *data, void *private);
        void *private;
        struct iio_channel *channels;
        struct iio_dev *indio_dev;
};

static struct iio_cb_buffer *buffer_to_cb_buffer(struct iio_buffer *buffer)
{
        return container_of(buffer, struct iio_cb_buffer, buffer);
}

static int iio_buffer_cb_store_to(struct iio_buffer *buffer, const void *data)
{
        struct iio_cb_buffer *cb_buff = buffer_to_cb_buffer(buffer);
        return cb_buff->cb(data, cb_buff->private);
}

static void iio_buffer_cb_release(struct iio_buffer *buffer)
{
        struct iio_cb_buffer *cb_buff = buffer_to_cb_buffer(buffer);

        bitmap_free(cb_buff->buffer.scan_mask);
        kfree(cb_buff);
}

static const struct iio_buffer_access_funcs iio_cb_access = {
        .store_to = &iio_buffer_cb_store_to,
        .release = &iio_buffer_cb_release,

        .modes = INDIO_BUFFER_SOFTWARE | INDIO_BUFFER_TRIGGERED,
};

struct iio_cb_buffer *iio_channel_get_all_cb(struct device *dev,
                                             int (*cb)(const void *data,
                                                       void *private),
                                             void *private)
{
        int ret;
        struct iio_cb_buffer *cb_buff;
        struct iio_channel *chan;

        if (!cb) {
                dev_err(dev, "Invalid arguments: A callback must be provided!\n");
                return ERR_PTR(-EINVAL);
        }

        cb_buff = kzalloc_obj(*cb_buff);
        if (cb_buff == NULL)
                return ERR_PTR(-ENOMEM);

        iio_buffer_init(&cb_buff->buffer);

        cb_buff->private = private;
        cb_buff->cb = cb;
        cb_buff->buffer.access = &iio_cb_access;

        cb_buff->channels = iio_channel_get_all(dev);
        if (IS_ERR(cb_buff->channels)) {
                ret = PTR_ERR(cb_buff->channels);
                goto error_free_cb_buff;
        }

        cb_buff->indio_dev = cb_buff->channels[0].indio_dev;
        cb_buff->buffer.scan_mask = bitmap_zalloc(iio_get_masklength(cb_buff->indio_dev),
                                                  GFP_KERNEL);
        if (cb_buff->buffer.scan_mask == NULL) {
                ret = -ENOMEM;
                goto error_release_channels;
        }
        chan = &cb_buff->channels[0];
        while (chan->indio_dev) {
                if (chan->indio_dev != cb_buff->indio_dev) {
                        ret = -EINVAL;
                        goto error_free_scan_mask;
                }
                set_bit(chan->channel->scan_index,
                        cb_buff->buffer.scan_mask);
                chan++;
        }

        return cb_buff;

error_free_scan_mask:
        bitmap_free(cb_buff->buffer.scan_mask);
error_release_channels:
        iio_channel_release_all(cb_buff->channels);
error_free_cb_buff:
        kfree(cb_buff);
        return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(iio_channel_get_all_cb);

int iio_channel_cb_set_buffer_watermark(struct iio_cb_buffer *cb_buff,
                                        size_t watermark)
{
        if (!watermark)
                return -EINVAL;
        cb_buff->buffer.watermark = watermark;

        return 0;
}
EXPORT_SYMBOL_GPL(iio_channel_cb_set_buffer_watermark);

int iio_channel_start_all_cb(struct iio_cb_buffer *cb_buff)
{
        return iio_update_buffers(cb_buff->indio_dev, &cb_buff->buffer,
                                  NULL);
}
EXPORT_SYMBOL_GPL(iio_channel_start_all_cb);

void iio_channel_stop_all_cb(struct iio_cb_buffer *cb_buff)
{
        iio_update_buffers(cb_buff->indio_dev, NULL, &cb_buff->buffer);
}
EXPORT_SYMBOL_GPL(iio_channel_stop_all_cb);

void iio_channel_release_all_cb(struct iio_cb_buffer *cb_buff)
{
        iio_channel_release_all(cb_buff->channels);
        iio_buffer_put(&cb_buff->buffer);
}
EXPORT_SYMBOL_GPL(iio_channel_release_all_cb);

struct iio_channel
*iio_channel_cb_get_channels(const struct iio_cb_buffer *cb_buffer)
{
        return cb_buffer->channels;
}
EXPORT_SYMBOL_GPL(iio_channel_cb_get_channels);

struct iio_dev
*iio_channel_cb_get_iio_dev(const struct iio_cb_buffer *cb_buffer)
{
        return cb_buffer->indio_dev;
}
EXPORT_SYMBOL_GPL(iio_channel_cb_get_iio_dev);

MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
MODULE_DESCRIPTION("Industrial I/O callback buffer");
MODULE_LICENSE("GPL");