/* The industrial I/O core
*
* Copyright (c) 2008 Jonathan Cameron
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*
* Handling of buffer allocation / resizing.
*
*
* Things to look at here.
* - Better memory allocation techniques?
* - Alternative access techniques?
*/
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/iio/iio.h>
#include "iio_core.h"
#include <linux/iio/sysfs.h>
#include <linux/iio/buffer.h>
static const char * const iio_endian_prefix[] = {
[IIO_BE] = "be",
[IIO_LE] = "le",
};
static bool iio_buffer_is_active(struct iio_buffer *buf)
{
return !list_empty(&buf->buffer_list);
}
static size_t iio_buffer_data_available(struct iio_buffer *buf)
{
return buf->access->data_available(buf);
}
static bool iio_buffer_ready(struct iio_dev *indio_dev, struct iio_buffer *buf,
size_t to_wait)
{
/* wakeup if the device was unregistered */
if (!indio_dev->info)
return true;
/* drain the buffer if it was disabled */
if (!iio_buffer_is_active(buf))
to_wait = min_t(size_t, to_wait, 1);
if (iio_buffer_data_available(buf) >= to_wait)
return true;
return false;
}
/**
* iio_buffer_read_first_n_outer() - chrdev read for buffer access
*
* This function relies on all buffer implementations having an
* iio_buffer as their first element.
**/
ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
size_t n, loff_t *f_ps)
{
struct iio_dev *indio_dev = filp->private_data;
struct iio_buffer *rb = indio_dev->buffer;
size_t datum_size;
size_t to_wait = 0;
int ret;
if (!indio_dev->info)
return -ENODEV;
if (!rb || !rb->access->read_first_n)
return -EINVAL;
datum_size = rb->bytes_per_datum;
/*
* If datum_size is 0 there will never be anything to read from the
* buffer, so signal end of file now.
*/
if (!datum_size)
return 0;
if (!(filp->f_flags & O_NONBLOCK))
to_wait = min_t(size_t, n / datum_size, rb->watermark);
do {
ret = wait_event_interruptible(rb->pollq,
iio_buffer_ready(indio_dev, rb, to_wait));
if (ret)
return ret;
if (!indio_dev->info)
return -ENODEV;
ret = rb->access->read_first_n(rb, n, buf);
if (ret == 0 &&