path: root/drivers/iio/industrialio-buffer.c

/* 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/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_dev *indio_dev,
				 struct iio_buffer *buf)
{
	struct list_head *p;

	list_for_each(p, &indio_dev->buffer_list)
		if (p == &buf->buffer_list)
			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;

	if (!rb || !rb->access->read_first_n)
		return -EINVAL;
	return rb->access->read_first_n(rb, n, buf);
}

/**
 * iio_buffer_poll() - poll the buffer to find out if it has data
 */
unsigned int iio_buffer_poll(struct file *filp,
			     struct poll_table_struct *wait)
{
	struct iio_dev *indio_dev = filp->private_data;
	struct iio_buffer *rb = indio_dev->buffer;

	poll_wait(filp, &rb->pollq, wait);
	if (rb->stufftoread)
		return POLLIN | POLLRDNORM;
	/* need a way of knowing if there may be enough data... */
	return 0;
}

void iio_buffer_init(struct iio_buffer *buffer)
{
	INIT_LIST_HEAD(&buffer->demux_list);
	init_waitqueue_head(&buffer->pollq);
}
EXPORT_SYMBOL(iio_buffer_init);

static ssize_t iio_show_scan_index(struct device *dev,
				   struct device_attribute *attr,
				   char *buf)
{
	return sprintf(buf, "%u\n", to_iio_dev_attr(attr)->c->scan_index);
}

static ssize_t iio_show_fixed_type(struct device *dev,
				   struct device_attribute *attr,
				   char *buf)
{
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
	u8 type = this_attr->c->scan_type.endianness;

	if (type == IIO_CPU) {
#ifdef __LITTLE_ENDIAN
		type = IIO_LE;
#else
		type = IIO_BE;
#endif
	}
	return sprintf(buf, "%s:%c%d/%d>>%u\n",
		       iio_endian_prefix[type],
		       this_attr->c->scan_type.sign,
		       this_attr->c->scan_type.realbits,
		       this_attr->c->scan_type.storagebits,
		       this_attr->c->scan_type.shift);
}

static ssize_t iio_scan_el_show(struct device *dev,
				struct device_attribute *attr,
				char *buf)
{
	int ret;
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);

	ret = test_bit(to_iio_dev_attr(attr)->address,
		       indio_dev->buffer->scan_mask);

	return sprintf(buf, "%d\n", ret);
}

static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
{
	clear_bit(bit, buffer->scan_mask);
	return 0;
}

static ssize_t iio_scan_el_store(struct device *dev,
				 struct device_attribute *attr,
				 const char *buf,
				 size_t len)
{
	int ret;
	bool state;
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct iio_buffer *buffer = indio_dev->buffer;
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);

	ret = strtobool(buf, &state);
	if (ret < 0)
		return ret;
	mutex_lock(&indio_dev->mlock);
	if (iio_buffer_is_active(indio_dev, indio_dev->buffer)) {
		ret = -EBUSY;
		goto error_ret;
	}
	ret = iio_scan_mask_query(indio_dev, buffer, this_attr->address);
	if (ret < 0)
		goto error_ret;
	if (!state && ret) {
		ret = iio_scan_mask_clear(buffer, this_attr->address);
		if (ret)
			goto