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/******************************************************************************
* Copyright (c) 2016 IBM Corporation
* All rights reserved.
* This program and the accompanying materials
* are made available under the terms of the BSD License
* which accompanies this distribution, and is available at
* http://www.opensource.org/licenses/bsd-license.php
*
* Contributors:
* IBM Corporation - initial implementation
*****************************************************************************/
/*
* Virtio serial device definitions.
* See Virtio 1.0 - 5.3 Console Device, for details
*/
#include <stdio.h>
#include <string.h>
#include <cpu.h>
#include <helpers.h>
#include <byteorder.h>
#include "virtio.h"
#include "virtio-serial.h"
#include "virtio-internal.h"
#define DRIVER_FEATURE_SUPPORT VIRTIO_F_VERSION_1
#define RX_ELEM_SIZE 4
#define RX_NUM_ELEMS 128
#define RX_Q 0
#define TX_Q 1
static uint16_t last_rx_idx; /* Last index in RX "used" ring */
int virtio_serial_init(struct virtio_device *dev)
{
struct vqs *vq_rx, *vq_tx;
int status = VIRTIO_STAT_ACKNOWLEDGE;
int i;
/* Reset device */
virtio_reset_device(dev);
/* Acknowledge device. */
virtio_set_status(dev, status);
/* Tell HV that we know how to drive the device. */
status |= VIRTIO_STAT_DRIVER;
virtio_set_status(dev, status);
if (dev->features & VIRTIO_F_VERSION_1) {
/* Negotiate features and sets FEATURES_OK if successful */
if (virtio_negotiate_guest_features(dev, DRIVER_FEATURE_SUPPORT))
goto dev_error;
virtio_get_status(dev, &status);
}
vq_rx = virtio_queue_init_vq(dev, RX_Q);
if (!vq_rx)
goto dev_error;
/* Allocate memory for multiple receive buffers */
vq_rx->buf_mem = SLOF_alloc_mem(RX_ELEM_SIZE * RX_NUM_ELEMS);
if (!vq_rx->buf_mem) {
printf("virtio-serial: Failed to allocate buffers!\n");
goto dev_error;
}
/* Prepare receive buffer queue */
for (i = 0; i < RX_NUM_ELEMS; i++) {
uint64_t addr = (uint64_t)vq_rx->buf_mem + i * RX_ELEM_SIZE;
/* Descriptor for data: */
virtio_fill_desc(vq_rx, i, dev->features, addr, 1, VRING_DESC_F_WRITE, 0);
vq_rx->avail->ring[i] = virtio_cpu_to_modern16(dev, i);
}
vq_rx->avail->idx = virtio_cpu_to_modern16(dev, RX_NUM_ELEMS);
sync();
last_rx_idx = virtio_modern16_to_cpu(dev, vq_rx->used->idx);
vq_tx = virtio_queue_init_vq(dev, TX_Q);
if (!vq_tx)
goto dev_error;
/* Tell HV that setup succeeded */
status |= VIRTIO_STAT_DRIVER_OK;
virtio_set_status(dev, status);
return 1;
dev_error:
printf("%s: failed\n", __func__);
status |= VIRTIO_STAT_FAILED;
virtio_set_status(dev, status);
return 0;
}
void virtio_serial_shutdown(struct virtio_device *dev)
{
/* Quiesce device */
virtio_set_status(dev, VIRTIO_STAT_FAILED);
/* Reset device */
virtio_reset_device(dev);
}
int virtio_serial_putchar(struct virtio_device *dev, char c)
{
int id, ret;
uint32_t time;
volatile uint16_t *current_used_idx;
uint16_t last_used_idx, avail_idx;
struct vqs *vq = &dev->vq[TX_Q];
avail_idx = virtio_modern16_to_cpu(dev, vq->avail->idx);
last_used_idx = vq->used->idx;
current_used_idx = &vq->used->idx;
/* Determine descriptor index */
id = avail_idx % vq->size;
/* Set up virtqueue descriptor for header */
virtio_fill_desc(vq, id, dev->features, (uint64_t)&c, 1, 0, 0);
vq->avail->ring[avail_idx % vq->size] = virtio_cpu_to_modern16 (dev, id);
mb();
vq->avail->idx = virtio_cpu_to_modern16(dev, avail_idx + 1);
/* Tell HV that the queue is ready */
virtio_queue_notify(dev, TX_Q);
/* Wait for host to consume the descriptor */
ret = 1;
time = SLOF_GetTimer() + VIRTIO_TIMEOUT;
while (*current_used_idx == last_used_idx) {
// do something better
mb();
if (time < SLOF_GetTimer()) {
printf("virtio_serial_putchar failed! \n");
ret = 0;
break;
}
}
virtio_free_desc(vq, id, dev->features);
return ret;
}
char virtio_serial_getchar(struct virtio_device *dev)
{
int id, idx;
char buf[RX_NUM_ELEMS] = {0};
uint16_t avail_idx;
struct vqs *vq_rx = &dev->vq[RX_Q];
idx = virtio_modern16_to_cpu(dev, vq_rx->used->idx);
if (last_rx_idx == idx) {
/* Nothing received yet */
return 0;
}
id = (virtio_modern32_to_cpu(dev, vq_rx->used->ring[last_rx_idx % vq_rx->size].id) + 1)
% vq_rx->size;
/* Copy data to destination buffer */
memcpy(buf, virtio_desc_addr(dev, RX_Q, id - 1), RX_ELEM_SIZE);
/* Move indices to next entries */
last_rx_idx = last_rx_idx + 1;
avail_idx = virtio_modern16_to_cpu(dev, vq_rx->avail->idx);
vq_rx->avail->ring[avail_idx % vq_rx->size] = virtio_cpu_to_modern16(dev, id - 1);
sync();
vq_rx->avail->idx = virtio_cpu_to_modern16(dev, avail_idx + 1);
sync();
/* Tell HV that RX queue entry is ready */
virtio_queue_notify(dev, RX_Q);
return buf[0];
}
int virtio_serial_haschar(struct virtio_device *dev)
{
struct vqs *vq_rx = &dev->vq[RX_Q];
if (last_rx_idx == virtio_modern16_to_cpu(dev, vq_rx->used->idx))
return 0;
else
return 1;
}
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