From c6fa443b3dab9f49fb157b0164f5852fde68ed3b Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Tue, 13 May 2014 16:09:36 +0100 Subject: [PATCH] hw/net/stellaris_enet: Rewrite tx fifo handling code 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 Reviewed-by: Dr. David Alan Gilbert --- 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 d0da819616..b99f93e732 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++) {