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hw/net/stellaris_enet: Rewrite tx fifo handling code

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The datasheet is clear that the frame length written to the DATA
register is actually stored in the TX FIFO; this means we don't
need to keep both tx_frame_len and tx_fifo_len state separately.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Peter Maydell 2014-05-13 16:09:36 +01:00
parent 7fd5f064d1
commit c6fa443b3d
1 changed files with 77 additions and 42 deletions
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119
hw/net/stellaris_enet.c
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@ -59,7 +59,6 @@ typedef struct {
uint32_t mtxd;
uint32_t mrxd;
uint32_t np;
int tx_frame_len;
int tx_fifo_len;
uint8_t tx_fifo[2048];
/* Real hardware has a 2k fifo, which works out to be at most 31 packets.
@ -82,6 +81,62 @@ static void stellaris_enet_update(stellaris_enet_state *s)
qemu_set_irq(s->irq, (s->ris & s->im) != 0);
}
/* Return the data length of the packet currently being assembled
* in the TX fifo.
*/
static inline int stellaris_txpacket_datalen(stellaris_enet_state *s)
{
return s->tx_fifo[0] | (s->tx_fifo[1] << 8);
}
/* Return true if the packet currently in the TX FIFO is complete,
* ie the FIFO holds enough bytes for the data length, ethernet header,
* payload and optionally CRC.
*/
static inline bool stellaris_txpacket_complete(stellaris_enet_state *s)
{
int framelen = stellaris_txpacket_datalen(s);
framelen += 16;
if (!(s->tctl & SE_TCTL_CRC)) {
framelen += 4;
}
/* Cover the corner case of a 2032 byte payload with auto-CRC disabled:
* this requires more bytes than will fit in the FIFO. It's not totally
* clear how the h/w handles this, but if using threshold-based TX
* it will definitely try to transmit something.
*/
framelen = MIN(framelen, ARRAY_SIZE(s->tx_fifo));
return s->tx_fifo_len >= framelen;
}
/* Send the packet currently in the TX FIFO */
static void stellaris_enet_send(stellaris_enet_state *s)
{
int framelen = stellaris_txpacket_datalen(s);
/* Ethernet header is in the FIFO but not in the datacount.
* We don't implement explicit CRC, so just ignore any
* CRC value in the FIFO.
*/
framelen += 14;
if ((s->tctl & SE_TCTL_PADEN) && framelen < 60) {
memset(&s->tx_fifo[framelen + 2], 0, 60 - framelen);
framelen = 60;
}
/* This MIN will have no effect unless the FIFO data is corrupt
* (eg bad data from an incoming migration); otherwise the check
* on the datalen at the start of writing the data into the FIFO
* will have caught this. Silently write a corrupt half-packet,
* which is what the hardware does in FIFO underrun situations.
*/
framelen = MIN(framelen, ARRAY_SIZE(s->tx_fifo) - 2);
qemu_send_packet(qemu_get_queue(s->nic), s->tx_fifo + 2, framelen);
s->tx_fifo_len = 0;
s->ris |= SE_INT_TXEMP;
stellaris_enet_update(s);
DPRINTF("Done TX\n");
}
/* TODO: Implement MAC address filtering. */
static ssize_t stellaris_enet_receive(NetClientState *nc, const uint8_t *buf, size_t size)
{
@ -215,8 +270,9 @@ static void stellaris_enet_write(void *opaque, hwaddr offset,
DPRINTF("IRQ ack %02x/%02x\n", value, s->ris);
stellaris_enet_update(s);
/* Clearing TXER also resets the TX fifo. */
if (value & SE_INT_TXER)
s->tx_frame_len = -1;
if (value & SE_INT_TXER) {
s->tx_fifo_len = 0;
}
break;
case 0x04: /* IM */
DPRINTF("IRQ mask %02x/%02x\n", value, s->ris);
@ -235,46 +291,27 @@ static void stellaris_enet_write(void *opaque, hwaddr offset,
s->tctl = value;
break;
case 0x10: /* DATA */
if (s->tx_frame_len == -1) {
s->tx_frame_len = value & 0xffff;
if (s->tx_frame_len > 2032) {
DPRINTF("TX frame too long (%d)\n", s->tx_frame_len);
s->tx_frame_len = 0;
if (s->tx_fifo_len == 0) {
/* The first word is special, it contains the data length */
int framelen = value & 0xffff;
if (framelen > 2032) {
DPRINTF("TX frame too long (%d)\n", framelen);
s->ris |= SE_INT_TXER;
stellaris_enet_update(s);
} else {
DPRINTF("Start TX frame len=%d\n", s->tx_frame_len);
/* The value written does not include the ethernet header. */
s->tx_frame_len += 14;
if ((s->tctl & SE_TCTL_CRC) == 0)
s->tx_frame_len += 4;
s->tx_fifo_len = 0;
s->tx_fifo[s->tx_fifo_len++] = value >> 16;
s->tx_fifo[s->tx_fifo_len++] = value >> 24;
}
} else {
if (s->tx_fifo_len + 4 <= ARRAY_SIZE(s->tx_fifo)) {
s->tx_fifo[s->tx_fifo_len++] = value;
s->tx_fifo[s->tx_fifo_len++] = value >> 8;
s->tx_fifo[s->tx_fifo_len++] = value >> 16;
s->tx_fifo[s->tx_fifo_len++] = value >> 24;
}
if (s->tx_fifo_len >= s->tx_frame_len) {
/* We don't implement explicit CRC, so just chop it off. */
if ((s->tctl & SE_TCTL_CRC) == 0)
s->tx_frame_len -= 4;
if ((s->tctl & SE_TCTL_PADEN) && s->tx_frame_len < 60) {
memset(&s->tx_fifo[s->tx_frame_len], 0, 60 - s->tx_frame_len);
s->tx_frame_len = 60;
}
qemu_send_packet(qemu_get_queue(s->nic), s->tx_fifo,
s->tx_frame_len);
s->tx_frame_len = -1;
s->ris |= SE_INT_TXEMP;
stellaris_enet_update(s);
DPRINTF("Done TX\n");
break;
}
}
if (s->tx_fifo_len + 4 <= ARRAY_SIZE(s->tx_fifo)) {
s->tx_fifo[s->tx_fifo_len++] = value;
s->tx_fifo[s->tx_fifo_len++] = value >> 8;
s->tx_fifo[s->tx_fifo_len++] = value >> 16;
s->tx_fifo[s->tx_fifo_len++] = value >> 24;
}
if (stellaris_txpacket_complete(s)) {
stellaris_enet_send(s);
}
break;
case 0x14: /* IA0 */
s->conf.macaddr.a[0] = value;
@ -326,7 +363,7 @@ static void stellaris_enet_reset(stellaris_enet_state *s)
s->im = SE_INT_PHY | SE_INT_MD | SE_INT_RXER | SE_INT_FOV | SE_INT_TXEMP
| SE_INT_TXER | SE_INT_RX;
s->thr = 0x3f;
s->tx_frame_len = -1;
s->tx_fifo_len = 0;
}
static void stellaris_enet_save(QEMUFile *f, void *opaque)
@ -344,7 +381,6 @@ static void stellaris_enet_save(QEMUFile *f, void *opaque)
qemu_put_be32(f, s->mtxd);
qemu_put_be32(f, s->mrxd);
qemu_put_be32(f, s->np);
qemu_put_be32(f, s->tx_frame_len);
qemu_put_be32(f, s->tx_fifo_len);
qemu_put_buffer(f, s->tx_fifo, sizeof(s->tx_fifo));
for (i = 0; i < 31; i++) {
@ -375,7 +411,6 @@ static int stellaris_enet_load(QEMUFile *f, void *opaque, int version_id)
s->mtxd = qemu_get_be32(f);
s->mrxd = qemu_get_be32(f);
s->np = qemu_get_be32(f);
s->tx_frame_len = qemu_get_be32(f);
s->tx_fifo_len = qemu_get_be32(f);
qemu_get_buffer(f, s->tx_fifo, sizeof(s->tx_fifo));
for (i = 0; i < 31; i++) {