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/*
* Copyright 2007-2008 Freescale Semiconductor, Inc. All Rights Reserved.
*/
/*
* The code contained herein is licensed under the GNU General Public
* License. You may obtain a copy of the GNU General Public License
* Version 2 or later at the following locations:
*
* http://www.opensource.org/licenses/gpl-license.html
* http://www.gnu.org/copyleft/gpl.html
*/
#include <linux/slab.h>
#include <linux/hardirq.h>
#include "i2c_slave_ring_buffer.h"
i2c_slave_ring_buffer_t *i2c_slave_rb_alloc(int size)
{
i2c_slave_ring_buffer_t *ring_buf;
ring_buf =
(i2c_slave_ring_buffer_t *) kzalloc(sizeof(i2c_slave_ring_buffer_t),
GFP_KERNEL);
if (!ring_buf) {
pr_debug("%s: alloc ring_buf error\n", __func__);
goto error;
}
ring_buf->buffer = kmalloc(size, GFP_KERNEL);
if (!ring_buf->buffer) {
pr_debug("%s: alloc buffer error\n", __func__);
goto error1;
}
ring_buf->total = size;
ring_buf->lock = __SPIN_LOCK_UNLOCKED(ring_buf->lock);
return ring_buf;
error1:
kfree(ring_buf);
error:
return NULL;
}
void i2c_slave_rb_release(i2c_slave_ring_buffer_t *ring)
{
unsigned long flags;
spin_lock_irqsave(ring->lock, flags);
kfree(ring->buffer);
spin_unlock_irqrestore(ring->lock, flags);
kfree(ring);
}
int i2c_slave_rb_produce(i2c_slave_ring_buffer_t *ring, int num, char *data)
{
int ret = 0;
unsigned long flags;
spin_lock_irqsave(ring->lock, flags);
if (ring->start < ring->end) {
if ((ring->start + num) < ring->end) { /*have enough space */
memcpy(&ring->buffer[ring->start], data, num);
ring->start += num;
ret = num;
} else { /*space not enough, just copy part of it. */
ret = ring->end - ring->start;
memcpy(&ring->buffer[ring->start], data, ret);
ring->start += ret;
ring->full = 1;
}
} else if (ring->start >= ring->end && !ring->full) {
if (ring->start + num <= ring->total) { /*space enough */
ret = num;
memcpy(&ring->buffer[ring->start], data, ret);
ring->start += ret;
} else { /*turn ring->start around */
ret = ring->total - ring->start;
memcpy(&ring->buffer[ring->start], data, ret);
ring->start = 0;
num -= ret;
data += ret;
if (num < ring->end) { /*space enough */
ret += num;
memcpy(&ring->buffer[ring->start], data, num);
} else { /*space not enough, just copy part of it. */
ret += ring->end;
memcpy(&ring->buffer[ring->start], data,
ring->end);
ring->start = ring->end;
ring->full = 1;
}
}
} else { /*(ring->data == ring->end) && ring->full ) : full */
ret = 0;
}
spin_unlock_irqrestore(ring->lock, flags);
return ret;
}
int i2c_slave_rb_consume(i2c_slave_ring_buffer_t *ring, int num, char *data)
{
int ret;
unsigned long flags;
spin_lock_irqsave(ring->lock, flags);
if (num <= 0) {
ret = 0;
goto out;
}
if (ring->start > ring->end) {
if (num <= ring->start - ring->end) { /*enough */
ret = num;
memcpy(data, &ring->buffer[ring->end], ret);
ring->end += ret;
} else { /*not enough */
ret = ring->start - ring->end;
memcpy(data, &ring->buffer[ring->end], ret);
ring->end += ret;
}
} else if (ring->start < ring->end || ring->full) {
if (num <= ring->total - ring->end) {
ret = ring->total - ring->end;
memcpy(data, &ring->buffer[ring->end], ret);
ring->end += ret;
} else if (num <= ring->total - ring->end + ring->start) {
ret = ring->total - ring->end;
memcpy(data, &ring->buffer[ring->end], ret);
ring->end = 0;
data += ret;
num -= ret;
memcpy(data, &ring->buffer[ring->end], num);
ring->end = num;
ret += num;
} else {
ret = ring->total - ring->end;
memcpy(data, &ring->buffer[ring->end], ret);
ring->end = 0;
data += ret;
num -= ret;
memcpy(data, &ring->buffer[ring->end], ring->start);
ring->end = ring->start;
ret += ring->start;
}
ring->full = 0;
} else { /*empty */
ret = 0;
}
out:
spin_unlock_irqrestore(ring->lock, flags);
return ret;
}
int i2c_slave_rb_num(i2c_slave_ring_buffer_t *ring)
{
int ret;
unsigned long flags;
spin_lock_irqsave(ring->lock, flags);
if (ring->start > ring->end) {
ret = ring->start - ring->end;
} else if (ring->start < ring->end) {
ret = ring->total - ring->end + ring->start;
} else if (ring->full) {
ret = ring->total;
} else {
ret = 0;
}
spin_unlock_irqrestore(ring->lock, flags);
return ret;
}
void i2c_slave_rb_clear(i2c_slave_ring_buffer_t *ring)
{
unsigned long flags;
spin_lock_irqsave(ring->lock, flags);
ring->start = ring->end = 0;
ring->full = 0;
spin_unlock_irqrestore(ring->lock, flags);
}
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