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Tue, 11 Aug 2026 07:36:12 -0700 (PDT) Received: from localhost.localdomain ([198.16.145.87]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-90a6c26e074sm681286d6.2.2026.08.11.07.36.11 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 11 Aug 2026 07:36:12 -0700 (PDT) From: Marcelo Manzo To: qemu-devel@nongnu.org, qemu-arm@nongnu.org Cc: Peter Maydell , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Sergey Kambalin , Sergey Kambalin , Marcelo Manzo , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Jason Wang Subject: [PATCH v2 12/19] hw/net/bcm2838_genet: implement GENET TX path Date: Tue, 11 Aug 2026 10:35:49 -0400 Message-ID: <20260811143557.7862-13-marcelomanzo@gmail.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20260811143557.7862-1-marcelomanzo@gmail.com> References: <20260811143557.7862-1-marcelomanzo@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::f36; envelope-from=marcelomanzo@gmail.com; helo=mail-qv1-xf36.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Sergey Kambalin Implement the transmit DMA ring handling: walk TX descriptors between the consumer and producer index for a ring, pull frame data out of guest memory, and hand completed frames to the netdev peer via qemu_send_packet(), advancing the consumer index and raising the TXDMA_MBDONE interrupt as descriptors complete. Part of Sergey Kambalin's original Raspberry Pi 4B PCIe/GENET networking series (patchwork series 829638, posted to qemu-devel in 2024, never merged). Carried forward and completed by Marcelo Manzo; see the later "Fix TX ring activation check" patch for a real bug found and fixed in the ring-activity check this path depends on. Signed-off-by: Sergey Kambalin Signed-off-by: Marcelo Manzo --- hw/net/bcm2838_genet.c | 219 ++++++++++++++++++++++++++++++++- include/hw/net/bcm2838_genet.h | 17 +++ 2 files changed, 235 insertions(+), 1 deletion(-) diff --git a/hw/net/bcm2838_genet.c b/hw/net/bcm2838_genet.c index 6b3c9cb12b..1b02876094 100644 --- a/hw/net/bcm2838_genet.c +++ b/hw/net/bcm2838_genet.c @@ -237,6 +237,13 @@ REG16(GENET_PHY_EXP_SEL, 0) FIELD(GENET_PHY_EXP_SEL, REG_ID, 0, 8) FIELD(GENET_PHY_EXP_SEL, BLOCK_ID, 8, 8) +REG32(GENET_TX_CSUM_INFO, 0) +FIELD(GENET_TX_CSUM_INFO, OFFSET, 0, 15) +FIELD(GENET_TX_CSUM_INFO, PROTO_UDP, 15, 1) +FIELD(GENET_TX_CSUM_INFO, START, 16, 15) +FIELD(GENET_TX_CSUM_INFO, LV, 30, 1) + + static void bcm2838_genet_set_qemu_mac(BCM2838GenetState *s) { const MACAddr *addr = &s->nic_conf.macaddr; @@ -396,6 +403,216 @@ static uint64_t bcm2838_genet_mdio_cmd(BCM2838GenetState *s, uint64_t cmd) return cmd; } +static void bcm2838_genet_xmit_packet(NetClientState *s, void *packet, + size_t size) +{ + uint8_t *buf = packet + sizeof(BCM2838GenetXmitStatus); + size_t len = size; + uint16_t len_type = 0; + + len -= sizeof(BCM2838GenetXmitStatus); + net_checksum_calculate(buf, len, CSUM_ALL); + + memcpy(&len_type, &buf[12], sizeof(len_type)); + len_type = ntohs(len_type); + if (len_type < MAX_PAYLOAD_SIZE) { + len_type = len; + len_type = htons(len_type); + memcpy(&buf[12], &len_type, sizeof(len_type)); + } + + qemu_send_packet(s, buf, len); +} + +static uint64_t bcm2838_genet_tx(BCM2838GenetState *s, unsigned int ring_index, + uint32_t prod_index, + uint32_t cons_index) +{ + const unsigned int DESC_SIZE_WORDS + = sizeof(BCM2838GenetTdmaDesc) / sizeof(uint32_t); + const uint64_t RING_START_ADDR + = ((uint64_t)s->regs.tdma.rings[ring_index].start_addr_hi << 32) + + s->regs.tdma.rings[ring_index].start_addr; + const uint64_t RING_END_ADDR + = ((uint64_t)s->regs.tdma.rings[ring_index].end_addr_hi << 32) + + s->regs.tdma.rings[ring_index].end_addr; + + hwaddr data_addr; + uint64_t desc_index; + uint32_t desc_status = 0; + uint32_t buflength = 0; + uint64_t num_descs = 0; + uint64_t read_ptr + = ((uint64_t)s->regs.tdma.rings[ring_index].read_ptr_hi << 32) + + s->regs.tdma.rings[ring_index].read_ptr; + off_t packet_off = 0; + + uint32_t prod_index_fld = FIELD_EX32(prod_index, + GENET_DMA_PROD_INDEX, INDEX); + uint32_t cons_index_fld = FIELD_EX32(cons_index, + GENET_DMA_CONS_INDEX, INDEX); + + while (cons_index_fld != prod_index_fld) { + desc_index = read_ptr / DESC_SIZE_WORDS; + if (desc_index >= BCM2838_GENET_DMA_DESC_CNT) { + qemu_log_mask( + LOG_GUEST_ERROR, + "%s: invalid TX descriptor index %" PRIu64 " (exceeds %u)\n", + __func__, desc_index, BCM2838_GENET_DMA_DESC_CNT - 1); + break; + } + desc_status = s->regs.tdma.descs[desc_index].length_status; + data_addr = ((uint64_t)s->regs.tdma.descs[desc_index].address_hi << 32) + + s->regs.tdma.descs[desc_index].address_lo; + trace_bcm2838_genet_tx(ring_index, desc_index, desc_status, + data_addr); + + if (FIELD_EX32(desc_status, GENET_RDMA_LENGTH_STATUS, SOP) != 0) { + packet_off = 0; + } + + buflength = FIELD_EX32(desc_status, + GENET_RDMA_LENGTH_STATUS, BUFLENGTH); + + /* TODO: Add address_space_read() return value check */ + address_space_read(&s->dma_as, data_addr, + MEMTXATTRS_UNSPECIFIED, + s->tx_packet + packet_off, + buflength); + packet_off += buflength; + + if (FIELD_EX32(desc_status, GENET_RDMA_LENGTH_STATUS, EOP) != 0) { + bcm2838_genet_xmit_packet(qemu_get_queue(s->nic), s->tx_packet, + packet_off); + packet_off = 0; + } + + num_descs++; + cons_index_fld++; + s->regs.tdma.descs[desc_index].length_status = + FIELD_DP32(s->regs.tdma.descs[desc_index].length_status, + GENET_RDMA_LENGTH_STATUS, OWN, 1); + read_ptr = read_ptr == RING_END_ADDR + 1 - DESC_SIZE_WORDS + ? RING_START_ADDR : read_ptr + DESC_SIZE_WORDS; + } + + s->regs.tdma.rings[ring_index].read_ptr = read_ptr; + s->regs.tdma.rings[ring_index].read_ptr_hi = read_ptr >> 32; + + return num_descs; +} + +static bool bcm2838_genet_tdma_ring_active(BCM2838GenetState *s, + unsigned int ring_index) +{ + uint32_t ctrl_reg = s->regs.tdma.ctrl; + uint32_t ring_cfg_reg = s->regs.tdma.ring_cfg; + uint32_t ring_mask = 1 << ring_index; + bool dma_en = FIELD_EX32(ctrl_reg, GENET_DMA_CTRL, EN) != 0; + bool ring_en = + (FIELD_EX32(ring_cfg_reg, GENET_DMA_CTRL, EN) & ring_mask) != 0; + bool ring_buf_en = + (FIELD_EX32(ctrl_reg, GENET_DMA_CTRL, RING_BUF_EN) & ring_mask) != 0; + bool active = dma_en && ring_en && ring_buf_en; + + trace_bcm2838_genet_tx_dma_ring_active(ring_index, + active ? "active" : "halted"); + return active; +} + +static void bcm2838_genet_tdma(BCM2838GenetState *s, hwaddr offset, + uint64_t value) +{ + hwaddr ring_offset; + uint64_t num_descs_tx; + unsigned int ring_index; + uint32_t tx_intrs; + uint32_t cons_index; + uint32_t prod_index = value; + uint32_t ring_cfg = value; + uint32_t dma_ctrl = value; + + uint32_t cons_index_fld; + uint32_t prod_index_fld = + FIELD_EX32(prod_index, GENET_DMA_PROD_INDEX, INDEX); + + uint32_t exst_tdma_en = + FIELD_EX32(s->regs.tdma.ctrl, GENET_DMA_CTRL, EN); + uint32_t exst_ring_en = + FIELD_EX32(s->regs.tdma.ring_cfg, GENET_DMA_RING_CFG, EN); + uint32_t incm_tdma_en = + FIELD_EX32(dma_ctrl, GENET_DMA_CTRL, EN); + uint32_t incm_ring_en = + FIELD_EX32(ring_cfg, GENET_DMA_RING_CFG, EN); + uint32_t incm_ring_buf_en = + FIELD_EX32(dma_ctrl, GENET_DMA_CTRL, RING_BUF_EN); + + switch (offset) { + case BCM2838_GENET_TDMA_RINGS + ... BCM2838_GENET_TDMA_RINGS + sizeof(s->regs.tdma.rings) - 1: + ring_index = (offset - BCM2838_GENET_TDMA_RINGS) + / sizeof(BCM2838GenetTdmaRing); + if (bcm2838_genet_tdma_ring_active(s, ring_index)) { + ring_offset = offset - BCM2838_GENET_TDMA_RINGS + - ring_index * sizeof(BCM2838GenetTdmaRing); + switch (ring_offset) { + case BCM2838_GENET_TRING_PROD_INDEX: + cons_index = s->regs.tdma.rings[ring_index].cons_index; + cons_index_fld = FIELD_EX32(cons_index, + GENET_DMA_CONS_INDEX, INDEX); + if (cons_index_fld != prod_index_fld) { + trace_bcm2838_genet_tx_request(ring_index, + prod_index_fld, + cons_index_fld); + num_descs_tx = bcm2838_genet_tx(s, ring_index, prod_index, + cons_index); + if (num_descs_tx > 0) { + s->regs.tdma.rings[ring_index].cons_index = + FIELD_DP32(s->regs.tdma.rings[ring_index].cons_index, + GENET_DMA_CONS_INDEX, INDEX, + cons_index + num_descs_tx); + + if (ring_index == BCM2838_GENET_DMA_RING_DEFAULT) { + s->regs.intrl0.stat = + FIELD_DP32(s->regs.intrl0.stat, GENET_INTRL_0, + TXDMA_MBDONE, 1); + } else { + tx_intrs = FIELD_EX32(s->regs.intrl1.stat, + GENET_INTRL_1, TX_INTRS); + s->regs.intrl1.stat = + FIELD_DP32(s->regs.intrl1.stat, + GENET_INTRL_1, TX_INTRS, + tx_intrs | 1 << ring_index); + } + } + } + break; + default: + break; + } + } + break; + case BCM2838_GENET_TDMA_RING_CFG: + if (exst_ring_en != incm_ring_en) { + trace_bcm2838_genet_tx_dma_ring(incm_ring_en); + } + break; + case BCM2838_GENET_TDMA_CTRL: + s->regs.tdma.status = (~dma_ctrl) & GENET_DMA_ENABLE_MASK; + if (exst_tdma_en != incm_tdma_en) { + trace_bcm2838_genet_tx_dma(incm_tdma_en == 1 + ? "enabled" + : "disabled"); + } + if (exst_ring_en != incm_ring_buf_en) { + trace_bcm2838_genet_tx_dma_ring_buf(incm_ring_buf_en); + } + break; + default: + break; + } +} + static uint64_t bcm2838_genet_read(void *opaque, hwaddr offset, unsigned size) { uint64_t value = ~0; @@ -489,7 +706,7 @@ static void bcm2838_genet_write(void *opaque, hwaddr offset, uint64_t value, break; case BCM2838_GENET_TDMA_REGS ... BCM2838_GENET_TDMA_REGS + sizeof(BCM2838GenetRegsTdma) - 1: - qemu_log_mask(LOG_UNIMP, "TDMA isn't implemented yet"); + bcm2838_genet_tdma(s, offset, value); break; default: break; diff --git a/include/hw/net/bcm2838_genet.h b/include/hw/net/bcm2838_genet.h index b34c4b3ce7..bad582fe0d 100644 --- a/include/hw/net/bcm2838_genet.h +++ b/include/hw/net/bcm2838_genet.h @@ -110,6 +110,21 @@ OBJECT_DECLARE_SIMPLE_TYPE(BCM2838GenetState, BCM2838_GENET) #define BCM2838_GENET_PHY_EXP_SHD_BLOCKS_CNT 256 #define BCM2838_GENET_PHY_EXP_SHD_REGS_CNT 256 +#define MAX_FRAME_SIZE 0xFFF +#define MAX_PACKET_SIZE 1518 +#define MAX_PAYLOAD_SIZE 1500 +#define TX_MIN_PKT_SIZE 60 + + +typedef struct BCM2838GenetXmitStatus { + uint32_t length_status; /* length and peripheral status */ + uint32_t ext_status; /* Extended status */ + uint32_t rx_csum; /* partial rx checksum */ + uint32_t unused1[9]; /* unused */ + uint32_t tx_csum_info; /* Tx checksum info. */ + uint32_t unused2[3]; /* unused */ +} BCM2838GenetXmitStatus; + typedef struct { uint32_t rev_ctrl; uint32_t port_ctrl; @@ -405,6 +420,8 @@ struct BCM2838GenetState { qemu_irq irq_default; qemu_irq irq_prio; + + uint8_t tx_packet[MAX_FRAME_SIZE]; }; #endif /* BCM2838_GENET_H */ -- 2.47.1