/* virtio-net.c - etherboot driver for virtio network interface
 *
 * (c) Copyright 2008 Bull S.A.S.
 *
 *  Author: Laurent Vivier <Laurent.Vivier@bull.net>
 *
 * some parts from Linux Virtio PCI driver
 *
 *  Copyright IBM Corp. 2007
 *  Authors: Anthony Liguori  <aliguori@us.ibm.com>
 *
 *  some parts from Linux Virtio Ring
 *
 *  Copyright Rusty Russell IBM Corporation 2007
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 *
 *
 */

#include "etherboot.h"
#include "pci.h"
#include "nic.h"
#include "timer.h"
#include "virtio-ring.h"
#include "virtio-pci.h"
#include "virtio-net.h"

#define BUG() do { \
   printf("BUG: failure at %s:%d/%s()!\n", \
          __FILE__, __LINE__, __FUNCTION__); \
   while(1); \
} while (0)
#define BUG_ON(condition) do { if (condition) BUG(); } while (0)

/* Ethernet header */

struct eth_hdr {
   unsigned char dst_addr[ETH_ALEN];
   unsigned char src_addr[ETH_ALEN];
   unsigned short type;
};

struct eth_frame {
   struct eth_hdr hdr;
   unsigned char data[ETH_FRAME_LEN];
};

typedef unsigned char virtio_queue_t[PAGE_MASK + vring_size(MAX_QUEUE_NUM)];

/* TX: virtio header and eth buffer */

static struct virtio_net_hdr tx_virtio_hdr;
static struct eth_frame tx_eth_frame;

/* RX: virtio headers and buffers */

#define RX_BUF_NB  6
static struct virtio_net_hdr rx_hdr[RX_BUF_NB];
static unsigned char rx_buffer[RX_BUF_NB][ETH_FRAME_LEN];

/* virtio queues and vrings */

enum {
   RX_INDEX = 0,
   TX_INDEX,
   QUEUE_NB
};

static virtio_queue_t queue[QUEUE_NB];
static struct vring vring[QUEUE_NB];
static u16 free_head[QUEUE_NB];
static u16 last_used_idx[QUEUE_NB];
static u16 vdata[QUEUE_NB][MAX_QUEUE_NUM];

/*
 * Virtio PCI interface
 *
 */

static int vp_find_vq(struct nic *nic, int queue_index)
{
   struct vring * vr = &vring[queue_index];
   u16 num;

   /* select the queue */

   outw(queue_index, nic->ioaddr + VIRTIO_PCI_QUEUE_SEL);

   /* check if the queue is available */

   num = inw(nic->ioaddr + VIRTIO_PCI_QUEUE_NUM);
   if (!num) {
           printf("ERROR: queue size is 0\n");
           return -1;
   }

   if (num > MAX_QUEUE_NUM) {
           printf("ERROR: queue size %d > %d\n", num, MAX_QUEUE_NUM);
           return -1;
   }

   /* check if the queue is already active */

   if (inl(nic->ioaddr + VIRTIO_PCI_QUEUE_PFN)) {
           printf("ERROR: queue already active\n");
           return -1;
   }

   /* initialize the queue */

   vring_init(vr, num, (unsigned char*)&queue[queue_index]);

   /* activate the queue
    *
    * NOTE: vr->desc is initialized by vring_init()
    */

   outl((unsigned long)virt_to_phys(vr->desc) >> PAGE_SHIFT,
        nic->ioaddr + VIRTIO_PCI_QUEUE_PFN);

   return num;
}

/*
 * Virtual ring management
 *
 */

static void vring_enable_cb(int queue_index)
{
   vring[queue_index].avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT;
}

static void vring_disable_cb(int queue_index)
{
   vring[queue_index].avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
}

/*
 * vring_free
 *
 * put at the begin of the free list the current desc[head]
 */

static void vring_detach(int queue_index, unsigned int head)
{
   struct vring *vr = &vring[queue_index];
        unsigned int i;

        /* find end of given descriptor */

   i = head;
   while (vr->desc[i].flags & VRING_DESC_F_NEXT)
           i = vr->desc[i].next;

   /* link it with free list and point to it */

   vr->desc[i].next = free_head[queue_index];
   wmb();
   free_head[queue_index] = head;
}

/*
 * vring_more_used
 *
 * is there some used buffers ?
 *
 */

static inline int vring_more_used(int queue_index)
{
   wmb();
   return last_used_idx[queue_index] != vring[queue_index].used->idx;
}

/*
 * vring_get_buf
 *
 * get a buffer from the used list
 *
 */

static int vring_get_buf(int queue_index, unsigned int *len)
{
   struct vring *vr = &vring[queue_index];
   struct vring_used_elem *elem;
   u32 id;
   int ret;

   elem = &vr->used->ring[last_used_idx[queue_index] % vr->num];
   wmb();
   id = elem->id;
   if (len != NULL)
           *len = elem->len;

   ret = vdata[queue_index][id];

   vring_detach(queue_index, id);

   last_used_idx[queue_index]++;

   return ret;
}

static void vring_add_buf(int queue_index, int index, int num_added)
{
   struct vring *vr = &vring[queue_index];
   int i, avail, head;

   BUG_ON(queue_index >= QUEUE_NB);

   head = free_head[queue_index];
   i = head;

   if (queue_index == TX_INDEX) {

           BUG_ON(index != 0);

           /* add header into vring */

           vr->desc[i].flags = VRING_DESC_F_NEXT;
           vr->desc[i].addr = (u64)virt_to_phys(&tx_virtio_hdr);
           vr->desc[i].len = sizeof(struct virtio_net_hdr);
           i = vr->desc[i].next;

           /* add frame buffer into vring */

           vr->desc[i].flags = 0;
           vr->desc[i].addr = (u64)virt_to_phys(&tx_eth_frame);
           vr->desc[i].len = ETH_FRAME_LEN;
           i = vr->desc[i].next;

   } else if (queue_index == RX_INDEX) {

           BUG_ON(index >= RX_BUF_NB);

           /* add header into vring */

           vr->desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE;
           vr->desc[i].addr = (u64)virt_to_phys(&rx_hdr[index]);
           vr->desc[i].len = sizeof(struct virtio_net_hdr);
           i = vr->desc[i].next;

           /* add frame buffer into vring */

           vr->desc[i].flags = VRING_DESC_F_WRITE;
           vr->desc[i].addr = (u64)virt_to_phys(&rx_buffer[index]);
           vr->desc[i].len = ETH_FRAME_LEN;
           i = vr->desc[i].next;
   }

   free_head[queue_index] = i;

   vdata[queue_index][head] = index;

   avail = (vr->avail->idx + num_added) % vr->num;
   vr->avail->ring[avail] = head;
   wmb();
}

static void vring_kick(struct nic *nic, int queue_index, int num_added)
{
   struct vring *vr = &vring[queue_index];

   wmb();
   vr->avail->idx += num_added;

   mb();
   if (!(vr->used->flags & VRING_USED_F_NO_NOTIFY))
           vp_notify(nic, queue_index);
}

/*
 * virtnet_disable
 *
 * Turn off ethernet interface
 *
 */

static void virtnet_disable(struct dev *dev)
{
   int i;
   struct nic *nic = (struct nic *)dev;

   for (i = 0; i < QUEUE_NB; i++) {
           vring_disable_cb(i);
           vp_del_vq(nic, i);
   }
   vp_reset(nic);
}

/*
 * virtnet_poll
 *
 * Wait for a frame
 *
 * return true if there is a packet ready to read
 *
 * nic->packet should contain data on return
 * nic->packetlen should contain length of data
 *
 */
static int virtnet_poll(struct nic *nic, int retrieve)
{
   unsigned int len;
   u16 token;
   struct virtio_net_hdr *hdr;

   if (!vring_more_used(RX_INDEX))
           return 0;

   if (!retrieve)
           return 1;

   token = vring_get_buf(RX_INDEX, &len);

   BUG_ON(len > sizeof(struct virtio_net_hdr) + ETH_FRAME_LEN);

   hdr = &rx_hdr[token];   /* FIXME: check flags */
   len -= sizeof(struct virtio_net_hdr);

        nic->packetlen = len;
   memcpy(nic->packet, (char *)rx_buffer[token], nic->packetlen);

   /* add buffer to desc */

   vring_add_buf(RX_INDEX, token, 0);
   vring_kick(nic, RX_INDEX, 1);

   return 1;
}

/*
 *
 * virtnet_transmit
 *
 * Transmit a frame
 *
 */

static void virtnet_transmit(struct nic *nic, const char *destaddr,
        unsigned int type, unsigned int len, const char *data)
{
   /*
    * from http://www.etherboot.org/wiki/dev/devmanual :
    *     "You do not need more than one transmit buffer."
    */

   /* FIXME: initialize header according to vp_get_features() */

   tx_virtio_hdr.flags = 0;
   tx_virtio_hdr.csum_offset = 0;
   tx_virtio_hdr.csum_start = 0;
   tx_virtio_hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE;
   tx_virtio_hdr.gso_size = 0;
   tx_virtio_hdr.hdr_len = 0;

   /* add ethernet frame into vring */

   BUG_ON(len > sizeof(tx_eth_frame.data));

   memcpy(tx_eth_frame.hdr.dst_addr, destaddr, ETH_ALEN);
   memcpy(tx_eth_frame.hdr.src_addr, nic->node_addr, ETH_ALEN);
   tx_eth_frame.hdr.type = htons(type);
   memcpy(tx_eth_frame.data, data, len);

   vring_add_buf(TX_INDEX, 0, 0);

   /*
    * http://www.etherboot.org/wiki/dev/devmanual
    *
    *   "You should ensure the packet is fully transmitted
    *    before returning from this routine"
    */

   while (vring_more_used(TX_INDEX)) {
           mb();
           udelay(10);
           poll_interruptions();
   }

   vring_kick(nic, TX_INDEX, 1);

   /* free desc */

   (void)vring_get_buf(TX_INDEX, NULL);
}

static void virtnet_irq(struct nic *nic __unused, irq_action_t action)
{
   switch ( action ) {
   case DISABLE :
           vring_disable_cb(RX_INDEX);
           vring_disable_cb(TX_INDEX);
           break;
   case ENABLE :
           vring_enable_cb(RX_INDEX);
           vring_enable_cb(TX_INDEX);
           break;
   case FORCE :
           break;
   }
}

static void provide_buffers(struct nic *nic)
{
   int i;

   for (i = 0; i < RX_BUF_NB; i++)
           vring_add_buf(RX_INDEX, i, i);

   /* nofify */

   vring_kick(nic, RX_INDEX, i);
}

/*
 * virtnet_probe
 *
 * Look for a virtio network adapter
 *
 */

static int virtnet_probe(struct dev *dev, struct pci_device *pci)
{
   struct nic *nic = (struct nic *)dev;
   u32 features;
   int i;

   /* Mask the bit that says "this is an io addr" */

   nic->ioaddr = pci->ioaddr & ~3;

   /* Copy IRQ from PCI information */

   nic->irqno = pci->irq;

   printf("I/O address 0x%08x, IRQ #%d\n", nic->ioaddr, nic->irqno);

   adjust_pci_device(pci);

   vp_reset(nic);

   features = vp_get_features(nic);
   if (features & (1 << VIRTIO_NET_F_MAC)) {
           vp_get(nic, offsetof(struct virtio_net_config, mac),
                  nic->node_addr, ETH_ALEN);
           printf("MAC address %!\n", nic->node_addr);
   }

   /* initialize emit/receive queue */

   for (i = 0; i < QUEUE_NB; i++) {
           free_head[i] = 0;
           last_used_idx[i] = 0;
           memset((char*)&queue[i], 0, sizeof(queue[i]));
           if (vp_find_vq(nic, i) == -1)
                   printf("Cannot register queue #%d\n", i);
   }

   /* provide some receive buffers */

    provide_buffers(nic);

   /* define NIC interface */

   dev->disable = virtnet_disable;
   nic->poll = virtnet_poll;
   nic->transmit = virtnet_transmit;
   nic->irq = virtnet_irq;

   /* driver is ready */

   vp_set_features(nic, features & (1 << VIRTIO_NET_F_MAC));
   vp_set_status(nic, VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK);

   return 1;
}

static struct pci_id virtnet_nics[] = {
PCI_ROM(0x1af4, 0x1000, "virtio-net",              "Virtio Network Interface"),
};

static struct pci_driver virtnet_driver __pci_driver = {
   .type     = NIC_DRIVER,
   .name     = "VIRTIO-NET",
   .probe    = virtnet_probe,
   .ids      = virtnet_nics,
   .id_count = sizeof(virtnet_nics)/sizeof(virtnet_nics[0]),
   .class    = 0,
};
