diff options
Diffstat (limited to 'drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_tx.c')
-rw-r--r-- | drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_tx.c | 284 |
1 files changed, 284 insertions, 0 deletions
diff --git a/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_tx.c b/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_tx.c new file mode 100644 index 0000000000..04982e888c --- /dev/null +++ b/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_tx.c @@ -0,0 +1,284 @@ +// SPDX-License-Identifier: GPL-2.0-only OR BSD-3-Clause + +/* Packet transmit logic for Mellanox Gigabit Ethernet driver + * + * Copyright (C) 2020-2021 NVIDIA CORPORATION & AFFILIATES + */ + +#include <linux/skbuff.h> + +#include "mlxbf_gige.h" +#include "mlxbf_gige_regs.h" + +/* Transmit Initialization + * 1) Allocates TX WQE array using coherent DMA mapping + * 2) Allocates TX completion counter using coherent DMA mapping + */ +int mlxbf_gige_tx_init(struct mlxbf_gige *priv) +{ + size_t size; + + size = MLXBF_GIGE_TX_WQE_SZ * priv->tx_q_entries; + priv->tx_wqe_base = dma_alloc_coherent(priv->dev, size, + &priv->tx_wqe_base_dma, + GFP_KERNEL); + if (!priv->tx_wqe_base) + return -ENOMEM; + + priv->tx_wqe_next = priv->tx_wqe_base; + + /* Write TX WQE base address into MMIO reg */ + writeq(priv->tx_wqe_base_dma, priv->base + MLXBF_GIGE_TX_WQ_BASE); + + /* Allocate address for TX completion count */ + priv->tx_cc = dma_alloc_coherent(priv->dev, MLXBF_GIGE_TX_CC_SZ, + &priv->tx_cc_dma, GFP_KERNEL); + if (!priv->tx_cc) { + dma_free_coherent(priv->dev, size, + priv->tx_wqe_base, priv->tx_wqe_base_dma); + return -ENOMEM; + } + + /* Write TX CC base address into MMIO reg */ + writeq(priv->tx_cc_dma, priv->base + MLXBF_GIGE_TX_CI_UPDATE_ADDRESS); + + writeq(ilog2(priv->tx_q_entries), + priv->base + MLXBF_GIGE_TX_WQ_SIZE_LOG2); + + priv->prev_tx_ci = 0; + priv->tx_pi = 0; + + return 0; +} + +/* Transmit Deinitialization + * This routine will free allocations done by mlxbf_gige_tx_init(), + * namely the TX WQE array and the TX completion counter + */ +void mlxbf_gige_tx_deinit(struct mlxbf_gige *priv) +{ + u64 *tx_wqe_addr; + size_t size; + int i; + + tx_wqe_addr = priv->tx_wqe_base; + + for (i = 0; i < priv->tx_q_entries; i++) { + if (priv->tx_skb[i]) { + dma_unmap_single(priv->dev, *tx_wqe_addr, + priv->tx_skb[i]->len, DMA_TO_DEVICE); + dev_kfree_skb(priv->tx_skb[i]); + priv->tx_skb[i] = NULL; + } + tx_wqe_addr += 2; + } + + size = MLXBF_GIGE_TX_WQE_SZ * priv->tx_q_entries; + dma_free_coherent(priv->dev, size, + priv->tx_wqe_base, priv->tx_wqe_base_dma); + + dma_free_coherent(priv->dev, MLXBF_GIGE_TX_CC_SZ, + priv->tx_cc, priv->tx_cc_dma); + + priv->tx_wqe_base = NULL; + priv->tx_wqe_base_dma = 0; + priv->tx_cc = NULL; + priv->tx_cc_dma = 0; + priv->tx_wqe_next = NULL; + writeq(0, priv->base + MLXBF_GIGE_TX_WQ_BASE); + writeq(0, priv->base + MLXBF_GIGE_TX_CI_UPDATE_ADDRESS); +} + +/* Function that returns status of TX ring: + * 0: TX ring is full, i.e. there are no + * available un-used entries in TX ring. + * non-null: TX ring is not full, i.e. there are + * some available entries in TX ring. + * The non-null value is a measure of + * how many TX entries are available, but + * it is not the exact number of available + * entries (see below). + * + * The algorithm makes the assumption that if + * (prev_tx_ci == tx_pi) then the TX ring is empty. + * An empty ring actually has (tx_q_entries-1) + * entries, which allows the algorithm to differentiate + * the case of an empty ring vs. a full ring. + */ +static u16 mlxbf_gige_tx_buffs_avail(struct mlxbf_gige *priv) +{ + unsigned long flags; + u16 avail; + + spin_lock_irqsave(&priv->lock, flags); + + if (priv->prev_tx_ci == priv->tx_pi) + avail = priv->tx_q_entries - 1; + else + avail = ((priv->tx_q_entries + priv->prev_tx_ci - priv->tx_pi) + % priv->tx_q_entries) - 1; + + spin_unlock_irqrestore(&priv->lock, flags); + + return avail; +} + +bool mlxbf_gige_handle_tx_complete(struct mlxbf_gige *priv) +{ + struct net_device_stats *stats; + u16 tx_wqe_index; + u64 *tx_wqe_addr; + u64 tx_status; + u16 tx_ci; + + tx_status = readq(priv->base + MLXBF_GIGE_TX_STATUS); + if (tx_status & MLXBF_GIGE_TX_STATUS_DATA_FIFO_FULL) + priv->stats.tx_fifo_full++; + tx_ci = readq(priv->base + MLXBF_GIGE_TX_CONSUMER_INDEX); + stats = &priv->netdev->stats; + + /* Transmit completion logic needs to loop until the completion + * index (in SW) equals TX consumer index (from HW). These + * parameters are unsigned 16-bit values and the wrap case needs + * to be supported, that is TX consumer index wrapped from 0xFFFF + * to 0 while TX completion index is still < 0xFFFF. + */ + for (; priv->prev_tx_ci != tx_ci; priv->prev_tx_ci++) { + tx_wqe_index = priv->prev_tx_ci % priv->tx_q_entries; + /* Each TX WQE is 16 bytes. The 8 MSB store the 2KB TX + * buffer address and the 8 LSB contain information + * about the TX WQE. + */ + tx_wqe_addr = priv->tx_wqe_base + + (tx_wqe_index * MLXBF_GIGE_TX_WQE_SZ_QWORDS); + + stats->tx_packets++; + stats->tx_bytes += MLXBF_GIGE_TX_WQE_PKT_LEN(tx_wqe_addr); + + dma_unmap_single(priv->dev, *tx_wqe_addr, + priv->tx_skb[tx_wqe_index]->len, DMA_TO_DEVICE); + dev_consume_skb_any(priv->tx_skb[tx_wqe_index]); + priv->tx_skb[tx_wqe_index] = NULL; + + /* Ensure completion of updates across all cores */ + mb(); + } + + /* Since the TX ring was likely just drained, check if TX queue + * had previously been stopped and now that there are TX buffers + * available the TX queue can be awakened. + */ + if (netif_queue_stopped(priv->netdev) && + mlxbf_gige_tx_buffs_avail(priv)) + netif_wake_queue(priv->netdev); + + return true; +} + +/* Function to advance the tx_wqe_next pointer to next TX WQE */ +void mlxbf_gige_update_tx_wqe_next(struct mlxbf_gige *priv) +{ + /* Advance tx_wqe_next pointer */ + priv->tx_wqe_next += MLXBF_GIGE_TX_WQE_SZ_QWORDS; + + /* Check if 'next' pointer is beyond end of TX ring */ + /* If so, set 'next' back to 'base' pointer of ring */ + if (priv->tx_wqe_next == (priv->tx_wqe_base + + (priv->tx_q_entries * MLXBF_GIGE_TX_WQE_SZ_QWORDS))) + priv->tx_wqe_next = priv->tx_wqe_base; +} + +netdev_tx_t mlxbf_gige_start_xmit(struct sk_buff *skb, + struct net_device *netdev) +{ + struct mlxbf_gige *priv = netdev_priv(netdev); + long buff_addr, start_dma_page, end_dma_page; + struct sk_buff *tx_skb; + dma_addr_t tx_buf_dma; + unsigned long flags; + u64 *tx_wqe_addr; + u64 word2; + + /* If needed, linearize TX SKB as hardware DMA expects this */ + if (skb->len > MLXBF_GIGE_DEFAULT_BUF_SZ || skb_linearize(skb)) { + dev_kfree_skb(skb); + netdev->stats.tx_dropped++; + return NETDEV_TX_OK; + } + + buff_addr = (long)skb->data; + start_dma_page = buff_addr >> MLXBF_GIGE_DMA_PAGE_SHIFT; + end_dma_page = (buff_addr + skb->len - 1) >> MLXBF_GIGE_DMA_PAGE_SHIFT; + + /* Verify that payload pointer and data length of SKB to be + * transmitted does not violate the hardware DMA limitation. + */ + if (start_dma_page != end_dma_page) { + /* DMA operation would fail as-is, alloc new aligned SKB */ + tx_skb = mlxbf_gige_alloc_skb(priv, skb->len, + &tx_buf_dma, DMA_TO_DEVICE); + if (!tx_skb) { + /* Free original skb, could not alloc new aligned SKB */ + dev_kfree_skb(skb); + netdev->stats.tx_dropped++; + return NETDEV_TX_OK; + } + + skb_put_data(tx_skb, skb->data, skb->len); + + /* Free the original SKB */ + dev_kfree_skb(skb); + } else { + tx_skb = skb; + tx_buf_dma = dma_map_single(priv->dev, skb->data, + skb->len, DMA_TO_DEVICE); + if (dma_mapping_error(priv->dev, tx_buf_dma)) { + dev_kfree_skb(skb); + netdev->stats.tx_dropped++; + return NETDEV_TX_OK; + } + } + + /* Get address of TX WQE */ + tx_wqe_addr = priv->tx_wqe_next; + + mlxbf_gige_update_tx_wqe_next(priv); + + /* Put PA of buffer address into first 64-bit word of TX WQE */ + *tx_wqe_addr = tx_buf_dma; + + /* Set TX WQE pkt_len appropriately + * NOTE: GigE silicon will automatically pad up to + * minimum packet length if needed. + */ + word2 = tx_skb->len & MLXBF_GIGE_TX_WQE_PKT_LEN_MASK; + + /* Write entire 2nd word of TX WQE */ + *(tx_wqe_addr + 1) = word2; + + spin_lock_irqsave(&priv->lock, flags); + priv->tx_skb[priv->tx_pi % priv->tx_q_entries] = tx_skb; + priv->tx_pi++; + spin_unlock_irqrestore(&priv->lock, flags); + + if (!netdev_xmit_more()) { + /* Create memory barrier before write to TX PI */ + wmb(); + writeq(priv->tx_pi, priv->base + MLXBF_GIGE_TX_PRODUCER_INDEX); + } + + /* Check if the last TX entry was just used */ + if (!mlxbf_gige_tx_buffs_avail(priv)) { + /* TX ring is full, inform stack */ + netif_stop_queue(netdev); + + /* Since there is no separate "TX complete" interrupt, need + * to explicitly schedule NAPI poll. This will trigger logic + * which processes TX completions, and will hopefully drain + * the TX ring allowing the TX queue to be awakened. + */ + napi_schedule(&priv->napi); + } + + return NETDEV_TX_OK; +} |