drivers/net/ethernet/stmicro/stmmac/chain_mode.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*******************************************************************************
   3   Specialised functions for managing Chained mode
   4
   5   Copyright(C) 2011  STMicroelectronics Ltd
   6
   7   It defines all the functions used to handle the normal/enhanced
   8   descriptors in case of the DMA is configured to work in chained or
   9   in ring mode.
  10
  11
  12   Author: Giuseppe Cavallaro <peppe.cavallaro@st.com>
  13 *******************************************************************************/
  14
  15 #include "stmmac.h"
  16
  17 static int jumbo_frm(void *p, struct sk_buff *skb, int csum)
  18 {
  19         struct stmmac_tx_queue *tx_q = (struct stmmac_tx_queue *)p;
  20         unsigned int nopaged_len = skb_headlen(skb);
  21         struct stmmac_priv *priv = tx_q->priv_data;
  22         unsigned int entry = tx_q->cur_tx;
  23         unsigned int bmax, des2;
  24         unsigned int i = 1, len;
  25         struct dma_desc *desc;
  26
  27         desc = tx_q->dma_tx + entry;
  28
  29         if (priv->plat->enh_desc)
  30                 bmax = BUF_SIZE_8KiB;
  31         else
  32                 bmax = BUF_SIZE_2KiB;
  33
  34         len = nopaged_len - bmax;
  35
  36         des2 = dma_map_single(priv->device, skb->data,
  37                               bmax, DMA_TO_DEVICE);
  38         desc->des2 = cpu_to_le32(des2);
  39         if (dma_mapping_error(priv->device, des2))
  40                 return -1;
  41         tx_q->tx_skbuff_dma[entry].buf = des2;
  42         tx_q->tx_skbuff_dma[entry].len = bmax;
  43         /* do not close the descriptor and do not set own bit */
  44         stmmac_prepare_tx_desc(priv, desc, 1, bmax, csum, STMMAC_CHAIN_MODE,
  45                         0, false, skb->len);
  46
  47         while (len != 0) {
  48                 tx_q->tx_skbuff[entry] = NULL;
  49                 entry = STMMAC_GET_ENTRY(entry, priv->dma_tx_size);
  50                 desc = tx_q->dma_tx + entry;
  51
  52                 if (len > bmax) {
  53                         des2 = dma_map_single(priv->device,
  54                                               (skb->data + bmax * i),
  55                                               bmax, DMA_TO_DEVICE);
  56                         desc->des2 = cpu_to_le32(des2);
  57                         if (dma_mapping_error(priv->device, des2))
  58                                 return -1;
  59                         tx_q->tx_skbuff_dma[entry].buf = des2;
  60                         tx_q->tx_skbuff_dma[entry].len = bmax;
  61                         stmmac_prepare_tx_desc(priv, desc, 0, bmax, csum,
  62                                         STMMAC_CHAIN_MODE, 1, false, skb->len);
  63                         len -= bmax;
  64                         i++;
  65                 } else {
  66                         des2 = dma_map_single(priv->device,
  67                                               (skb->data + bmax * i), len,
  68                                               DMA_TO_DEVICE);
  69                         desc->des2 = cpu_to_le32(des2);
  70                         if (dma_mapping_error(priv->device, des2))
  71                                 return -1;
  72                         tx_q->tx_skbuff_dma[entry].buf = des2;
  73                         tx_q->tx_skbuff_dma[entry].len = len;
  74                         /* last descriptor can be set now */
  75                         stmmac_prepare_tx_desc(priv, desc, 0, len, csum,
  76                                         STMMAC_CHAIN_MODE, 1, true, skb->len);
  77                         len = 0;
  78                 }
  79         }
  80
  81         tx_q->cur_tx = entry;
  82
  83         return entry;
  84 }
  85
  86 static unsigned int is_jumbo_frm(int len, int enh_desc)
  87 {
  88         unsigned int ret = 0;
  89
  90         if ((enh_desc && (len > BUF_SIZE_8KiB)) ||
  91             (!enh_desc && (len > BUF_SIZE_2KiB))) {
  92                 ret = 1;
  93         }
  94
  95         return ret;
  96 }
  97
  98 static void init_dma_chain(void *des, dma_addr_t phy_addr,
  99                                   unsigned int size, unsigned int extend_desc)
 100 {
 101         /*
 102          * In chained mode the des3 points to the next element in the ring.
 103          * The latest element has to point to the head.
 104          */
 105         int i;
 106         dma_addr_t dma_phy = phy_addr;
 107
 108         if (extend_desc) {
 109                 struct dma_extended_desc *p = (struct dma_extended_desc *)des;
 110                 for (i = 0; i < (size - 1); i++) {
 111                         dma_phy += sizeof(struct dma_extended_desc);
 112                         p->basic.des3 = cpu_to_le32((unsigned int)dma_phy);
 113                         p++;
 114                 }
 115                 p->basic.des3 = cpu_to_le32((unsigned int)phy_addr);
 116
 117         } else {
 118                 struct dma_desc *p = (struct dma_desc *)des;
 119                 for (i = 0; i < (size - 1); i++) {
 120                         dma_phy += sizeof(struct dma_desc);
 121                         p->des3 = cpu_to_le32((unsigned int)dma_phy);
 122                         p++;
 123                 }
 124                 p->des3 = cpu_to_le32((unsigned int)phy_addr);
 125         }
 126 }
 127
 128 static void refill_desc3(void *priv_ptr, struct dma_desc *p)
 129 {
 130         struct stmmac_rx_queue *rx_q = (struct stmmac_rx_queue *)priv_ptr;
 131         struct stmmac_priv *priv = rx_q->priv_data;
 132
 133         if (priv->hwts_rx_en && !priv->extend_desc)
 134                 /* NOTE: Device will overwrite des3 with timestamp value if
 135                  * 1588-2002 time stamping is enabled, hence reinitialize it
 136                  * to keep explicit chaining in the descriptor.
 137                  */
 138                 p->des3 = cpu_to_le32((unsigned int)(rx_q->dma_rx_phy +
 139                                       (((rx_q->dirty_rx) + 1) %
 140                                        priv->dma_rx_size) *
 141                                       sizeof(struct dma_desc)));
 142 }
 143
 144 static void clean_desc3(void *priv_ptr, struct dma_desc *p)
 145 {
 146         struct stmmac_tx_queue *tx_q = (struct stmmac_tx_queue *)priv_ptr;
 147         struct stmmac_priv *priv = tx_q->priv_data;
 148         unsigned int entry = tx_q->dirty_tx;
 149
 150         if (tx_q->tx_skbuff_dma[entry].last_segment && !priv->extend_desc &&
 151             priv->hwts_tx_en)
 152                 /* NOTE: Device will overwrite des3 with timestamp value if
 153                  * 1588-2002 time stamping is enabled, hence reinitialize it
 154                  * to keep explicit chaining in the descriptor.
 155                  */
 156                 p->des3 = cpu_to_le32((unsigned int)((tx_q->dma_tx_phy +
 157                                       ((tx_q->dirty_tx + 1) %
 158                                        priv->dma_tx_size))
 159                                       * sizeof(struct dma_desc)));
 160 }
 161
 162 const struct stmmac_mode_ops chain_mode_ops = {
 163         .init = init_dma_chain,
 164         .is_jumbo_frm = is_jumbo_frm,
 165         .jumbo_frm = jumbo_frm,
 166         .refill_desc3 = refill_desc3,
 167         .clean_desc3 = clean_desc3,
 168 };