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[Qemu-devel] [PATCH v3 3/7] hw/net/stellaris_enet: Rewrite tx fifo handl
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PATCH v3 3/7] hw/net/stellaris_enet: Rewrite tx fifo handling code |
Date: |
Mon, 28 Apr 2014 13:39:26 +0100 |
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 <address@hidden>
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
---
hw/net/stellaris_enet.c | 119 +++++++++++++++++++++++++++++++-----------------
1 file changed, 77 insertions(+), 42 deletions(-)
diff --git a/hw/net/stellaris_enet.c b/hw/net/stellaris_enet.c
index d0da819..b99f93e 100644
--- a/hw/net/stellaris_enet.c
+++ b/hw/net/stellaris_enet.c
@@ -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++) {
--
1.9.2
- [Qemu-devel] [PATCH v3 0/7] stellaris_enet: overhaul tx/rx, convert to vmstate, Peter Maydell, 2014/04/28
- [Qemu-devel] [PATCH v3 6/7] hw/net/stellaris_enet: Get rid of rx_fifo pointer, Peter Maydell, 2014/04/28
- [Qemu-devel] [PATCH v3 7/7] hw/net/stellaris_enet: Convert to vmstate, Peter Maydell, 2014/04/28
- [Qemu-devel] [PATCH v3 2/7] hw/net/stellaris_enet: Correct handling of packet padding, Peter Maydell, 2014/04/28
- [Qemu-devel] [PATCH v3 4/7] hw/net/stellaris_enet: Correctly implement the TR and THR registers, Peter Maydell, 2014/04/28
- [Qemu-devel] [PATCH v3 5/7] hw/net/stellaris_enet: Fix debug format strings, Peter Maydell, 2014/04/28
- [Qemu-devel] [PATCH v3 3/7] hw/net/stellaris_enet: Rewrite tx fifo handling code,
Peter Maydell <=
- [Qemu-devel] [PATCH v3 1/7] hw/net/stellaris_enet: Restructure tx_fifo code to avoid buffer overrun, Peter Maydell, 2014/04/28