lib/libvirtio/virtio.c

/******************************************************************************
 * Copyright (c) 2011 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
 *****************************************************************************/

#include <cpu.h>
#include <cache.h>
#include <byteorder.h>
#include "virtio.h"

/* PCI virtio header offsets */
#define VIRTIOHDR_DEVICE_FEATURES	0
#define VIRTIOHDR_GUEST_FEATURES	4
#define VIRTIOHDR_QUEUE_ADDRESS 	8
#define VIRTIOHDR_QUEUE_SIZE		12
#define VIRTIOHDR_QUEUE_SELECT		14
#define VIRTIOHDR_QUEUE_NOTIFY		16
#define VIRTIOHDR_DEVICE_STATUS 	18
#define VIRTIOHDR_ISR_STATUS		19
#define VIRTIOHDR_DEVICE_CONFIG 	20


/**
 * Calculate ring size according to queue size number
 */
unsigned long virtio_vring_size(unsigned int qsize)
{
	return VQ_ALIGN(sizeof(struct vring_desc) * qsize + 2 * (2 + qsize))
		+ VQ_ALIGN(sizeof(struct vring_used_elem) * qsize);
}


/**
 * Get number of elements in a vring
 * @param   dev  pointer to virtio device information
 * @param   queue virtio queue number
 * @return  number of elements
 */
int virtio_get_qsize(struct virtio_device *dev, int queue)
{
	int size = 0;

	if (dev->type == VIRTIO_TYPE_PCI) {
		ci_write_16(dev->base+VIRTIOHDR_QUEUE_SELECT,
			    cpu_to_le16(queue));
		eieio();
		size = le16_to_cpu(ci_read_16(dev->base+VIRTIOHDR_QUEUE_SIZE));
	}

	return size;
}


/**
 * Get address of descriptor vring
 * @param   dev  pointer to virtio device information
 * @param   queue virtio queue number
 * @return  pointer to the descriptor ring
 */
struct vring_desc *virtio_get_vring_desc(struct virtio_device *dev, int queue)
{
	struct vring_desc *desc = 0;

	if (dev->type == VIRTIO_TYPE_PCI) {
		ci_write_16(dev->base+VIRTIOHDR_QUEUE_SELECT,
			    cpu_to_le16(queue));
		eieio();
		desc = (void*)(4096L *
		   le32_to_cpu(ci_read_32(dev->base+VIRTIOHDR_QUEUE_ADDRESS)));
	}

	return desc;
}


/**
 * Get address of "available" vring
 * @param   dev  pointer to virtio device information
 * @param   queue virtio queue number
 * @return  pointer to the "available" ring
 */
struct vring_avail *virtio_get_vring_avail(struct virtio_device *dev, int queue)
{
	return (void*)((uint64_t)virtio_get_vring_desc(dev, queue)
			+ virtio_get_qsize(dev, queue) * sizeof(struct vring_desc));
}


/**
 * Get address of "used" vring
 * @param   dev  pointer to virtio device information
 * @param   queue virtio queue number
 * @return  pointer to the "used" ring
 */
struct vring_used *virtio_get_vring_used(struct virtio_device *dev, int queue)
{
	return (void*)VQ_ALIGN((uint64_t)virtio_get_vring_avail(dev, queue)
				  + virtio_get_qsize(dev, queue)
				    * sizeof(struct vring_avail));
}


/**
 * Reset virtio device
 */
void virtio_reset_device(struct virtio_device *dev)
{
	if (dev->type == VIRTIO_TYPE_PCI) {
		ci_write_8(dev->base+VIRTIOHDR_DEVICE_STATUS, 0);
	}
}


/**
 * Notify hypervisor about queue update
 */
void virtio_queue_notify(struct virtio_device *dev, int queue)
{
	if (dev->type == VIRTIO_TYPE_PCI) {
		ci_write_16(dev->base+VIRTIOHDR_QUEUE_NOTIFY, cpu_to_le16(queue));
	}
}

/**
 * Set queue address
 */
void virtio_set_qaddr(struct virtio_device *dev, int queue, unsigned int qaddr)
{
        if (dev->type == VIRTIO_TYPE_PCI) {
                uint32_t val = qaddr;
                val = val >> 12;
                ci_write_16(dev->base+VIRTIOHDR_QUEUE_SELECT,
                            cpu_to_le16(queue));
                eieio();
                ci_write_32(dev->base+VIRTIOHDR_QUEUE_ADDRESS,
                            cpu_to_le32(val));
        }
}

/**
 * Set device status bits
 */
void virtio_set_status(struct virtio_device *dev, int status)
{
	if (dev->type == VIRTIO_TYPE_PCI) {
		ci_write_8(dev->base+VIRTIOHDR_DEVICE_STATUS, status);
	}
}


/**
 * Set guest feature bits
 */
void virtio_set_guest_features(struct virtio_device *dev, int features)

{
	if (dev->type == VIRTIO_TYPE_PCI) {
		ci_write_32(dev->base+VIRTIOHDR_GUEST_FEATURES, features);
	}
}


/**
 * Get additional config values
 */
uint64_t virtio_get_config(struct virtio_device *dev, int offset, int size)
{
	uint64_t val = ~0ULL;
	void *confbase;

	switch (dev->type) {
	 case VIRTIO_TYPE_PCI:
		confbase = dev->base+VIRTIOHDR_DEVICE_CONFIG;
		break;
	 default:
		return ~0ULL;
	}
	switch (size) {
	 case 1:
		val = ci_read_8(confbase+offset);
		break;
	 case 2:
		val = ci_read_16(confbase+offset);
		break;
	 case 4:
		val = ci_read_32(confbase+offset);
		break;
	 case 8:
		/* We don't support 8 bytes PIO accesses
		 * in qemu and this is all PIO
		 */
		val = ci_read_32(confbase+offset);
		val <<= 32;
		val |= ci_read_32(confbase+offset+4);
		break;
	}

	return val;
}

/**
 * Get config blob
 */
int __virtio_read_config(struct virtio_device *dev, void *dst,
			  int offset, int len)
{
	void *confbase;
	unsigned char *buf = dst;
	int i;

	switch (dev->type) {
	 case VIRTIO_TYPE_PCI:
		confbase = dev->base+VIRTIOHDR_DEVICE_CONFIG;
		break;
	 default:
		return 0;
	}
	for (i = 0; i < len; i++)
		buf[i] = ci_read_8(confbase + offset + i);
	return len;
}