[PATCH 12/14] hw/net: GMAC Tx Implementation

[Nabih Estefan]

From: Nabih Estefan Diaz <nabihestefan@google.com>

- Implementation of Transmit function for packets
- Implementation for reading and writing from and to descriptors in
  memory for Tx

NOTE: This function implements the steps detailed in the datasheet for
transmitting messages from the GMAC.

Signed-off-by: Nabih Estefan Diaz <nabihestefan@google.com>
---
 hw/net/npcm_gmac.c | 150 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 150 insertions(+)

diff --git a/hw/net/npcm_gmac.c b/hw/net/npcm_gmac.c
index 67f123e3c4..c457b11e4d 100644
--- a/hw/net/npcm_gmac.c
+++ b/hw/net/npcm_gmac.c
@@ -266,6 +266,7 @@ static int gmac_write_tx_desc(dma_addr_t addr, struct 
NPCMGMACTxDesc *desc)
     }
     return 0;
 }
+
 static int gmac_rx_transfer_frame_to_buffer(uint32_t rx_buf_len,
                                             uint32_t *left_frame,
                                             uint32_t rx_buf_addr,
@@ -484,6 +485,155 @@ static ssize_t gmac_receive(NetClientState *nc, const 
uint8_t *buf, size_t len)
     gmac->regs[R_NPCM_DMA_HOST_RX_DESC] = desc_addr;
     return len;
 }
+
+static int gmac_tx_get_csum(uint32_t tdes1)
+{
+    uint32_t mask = TX_DESC_TDES1_CHKSM_INS_CTRL_MASK(tdes1);
+    int csum = 0;
+
+    if (likely(mask > 0)) {
+        csum |= CSUM_IP;
+    }
+    if (likely(mask > 1)) {
+        csum |= CSUM_TCP | CSUM_UDP;
+    }
+
+    return csum;
+}
+
+static void gmac_try_send_next_packet(NPCMGMACState *gmac)
+{
+    /*
+     * Comments about steps refer to steps for
+     * transmitting in page 384 of datasheet
+     */
+    uint16_t tx_buffer_size = 2048;
+    g_autofree uint8_t *tx_send_buffer = g_malloc(tx_buffer_size);
+    uint32_t desc_addr;
+    struct NPCMGMACTxDesc tx_desc;
+    uint32_t tx_buf_addr, tx_buf_len;
+    uint16_t length = 0;
+    uint8_t *buf = tx_send_buffer;
+    uint32_t prev_buf_size = 0;
+    int csum = 0;
+
+    /* steps 1&2 */
+    if (!gmac->regs[R_NPCM_DMA_HOST_TX_DESC]) {
+        gmac->regs[R_NPCM_DMA_HOST_TX_DESC] =
+            NPCM_DMA_HOST_TX_DESC_MASK(gmac->regs[R_NPCM_DMA_TX_BASE_ADDR]);
+    }
+    desc_addr = gmac->regs[R_NPCM_DMA_HOST_TX_DESC];
+
+    while (true) {
+        gmac_dma_set_state(gmac, NPCM_DMA_STATUS_TX_PROCESS_STATE_SHIFT,
+            NPCM_DMA_STATUS_TX_RUNNING_FETCHING_STATE);
+        trace_npcm_gmac_packet_transmit(DEVICE(gmac)->canonical_path, length);
+        if (gmac_read_tx_desc(desc_addr, &tx_desc)) {
+            qemu_log_mask(LOG_GUEST_ERROR, "TX Descriptor @ 0x%x can't be 
read\n",
+                          desc_addr);
+            return;
+        }
+        /* step 3 */
+
+        trace_npcm_gmac_packet_desc_read(DEVICE(gmac)->canonical_path, 
desc_addr);
+        trace_npcm_gmac_debug_desc_data(DEVICE(gmac)->canonical_path, &tx_desc,
+            tx_desc.tdes0, tx_desc.tdes1, tx_desc.tdes2, tx_desc.tdes3);
+
+        /* 1 = DMA Owned, 0 = Software Owned */
+        if (!(tx_desc.tdes0 & TX_DESC_TDES0_OWN)) {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "TX Descriptor @ 0x%x is owned by software\n",
+                          desc_addr);
+            gmac->regs[R_NPCM_DMA_STATUS] |= NPCM_DMA_STATUS_TU;
+            gmac_dma_set_state(gmac, NPCM_DMA_STATUS_TX_PROCESS_STATE_SHIFT,
+                NPCM_DMA_STATUS_TX_SUSPENDED_STATE);
+            gmac_update_irq(gmac);
+            return;
+        }
+
+        gmac_dma_set_state(gmac, NPCM_DMA_STATUS_TX_PROCESS_STATE_SHIFT,
+            NPCM_DMA_STATUS_TX_RUNNING_READ_STATE);
+        /* Give the descriptor back regardless of what happens. */
+        tx_desc.tdes0 &= ~TX_DESC_TDES0_OWN;
+
+        if (tx_desc.tdes1 & TX_DESC_TDES1_FIRST_SEG_MASK) {
+            csum = gmac_tx_get_csum(tx_desc.tdes1);
+        }
+
+        /* step 4 */
+        tx_buf_addr = tx_desc.tdes2;
+        gmac->regs[R_NPCM_DMA_CUR_TX_BUF_ADDR] = tx_buf_addr;
+        tx_buf_len = TX_DESC_TDES1_BFFR1_SZ_MASK(tx_desc.tdes1);
+        buf = &tx_send_buffer[prev_buf_size];
+
+        if ((prev_buf_size + tx_buf_len) > sizeof(buf)) {
+            tx_buffer_size = prev_buf_size + tx_buf_len;
+            tx_send_buffer = g_realloc(tx_send_buffer, tx_buffer_size);
+            buf = &tx_send_buffer[prev_buf_size];
+        }
+
+        /* step 5 */
+        if (dma_memory_read(&address_space_memory, tx_buf_addr, buf,
+                            tx_buf_len, MEMTXATTRS_UNSPECIFIED)) {
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: Failed to read packet @ 
0x%x\n",
+                        __func__, tx_buf_addr);
+            return;
+        }
+        length += tx_buf_len;
+        prev_buf_size += tx_buf_len;
+
+        /* If not chained we'll have a second buffer. */
+        if (!(tx_desc.tdes1 & TX_DESC_TDES1_SEC_ADDR_CHND_MASK)) {
+            tx_buf_addr = tx_desc.tdes3;
+            gmac->regs[R_NPCM_DMA_CUR_TX_BUF_ADDR] = tx_buf_addr;
+            tx_buf_len = TX_DESC_TDES1_BFFR2_SZ_MASK(tx_desc.tdes1);
+            buf = &tx_send_buffer[prev_buf_size];
+
+            if ((prev_buf_size + tx_buf_len) > sizeof(buf)) {
+                tx_buffer_size = prev_buf_size + tx_buf_len;
+                tx_send_buffer = g_realloc(tx_send_buffer, tx_buffer_size);
+                buf = &tx_send_buffer[prev_buf_size];
+            }
+
+            if (dma_memory_read(&address_space_memory, tx_buf_addr, buf,
+                                tx_buf_len, MEMTXATTRS_UNSPECIFIED)) {
+                qemu_log_mask(LOG_GUEST_ERROR,
+                              "%s: Failed to read packet @ 0x%x\n",
+                              __func__, tx_buf_addr);
+                return;
+            }
+            length += tx_buf_len;
+            prev_buf_size += tx_buf_len;
+        }
+        if (tx_desc.tdes1 & TX_DESC_TDES1_LAST_SEG_MASK) {
+            net_checksum_calculate(tx_send_buffer, length, csum);
+            qemu_send_packet(qemu_get_queue(gmac->nic), tx_send_buffer, 
length);
+            trace_npcm_gmac_packet_sent(DEVICE(gmac)->canonical_path, length);
+            buf = tx_send_buffer;
+            length = 0;
+        }
+
+        /* step 6 */
+        gmac_dma_set_state(gmac, NPCM_DMA_STATUS_TX_PROCESS_STATE_SHIFT,
+            NPCM_DMA_STATUS_TX_RUNNING_CLOSING_STATE);
+        gmac_write_tx_desc(desc_addr, &tx_desc);
+        if (tx_desc.tdes1 & TX_DESC_TDES1_TX_END_RING_MASK) {
+            desc_addr = gmac->regs[R_NPCM_DMA_TX_BASE_ADDR];
+        } else if (tx_desc.tdes1 & TX_DESC_TDES1_SEC_ADDR_CHND_MASK) {
+            desc_addr = tx_desc.tdes3;
+        } else {
+            desc_addr += sizeof(tx_desc);
+        }
+        gmac->regs[R_NPCM_DMA_HOST_TX_DESC] = desc_addr;
+
+        /* step 7 */
+        if (tx_desc.tdes1 & TX_DESC_TDES1_INTERR_COMP_MASK) {
+            gmac->regs[R_NPCM_DMA_STATUS] |= NPCM_DMA_STATUS_TI;
+            gmac_update_irq(gmac);
+        }
+    }
+}
+
 static void gmac_cleanup(NetClientState *nc)
 {
     /* Nothing to do yet. */
-- 
2.42.0.459.ge4e396fd5e-goog