1// SPDX-License-Identifier: GPL-2.0-only
2/*******************************************************************************
3 Specialised functions for managing Ring 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
17static int jumbo_frm(struct stmmac_tx_queue *tx_q, struct sk_buff *skb,
18 int csum)
19{
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, len, des2;
24 struct dma_desc *desc;
25
26 if (priv->extend_desc)
27 desc = (struct dma_desc *)(tx_q->dma_etx + entry);
28 else
29 desc = tx_q->dma_tx + entry;
30
31 if (priv->plat->enh_desc)
32 bmax = BUF_SIZE_8KiB;
33 else
34 bmax = BUF_SIZE_2KiB;
35
36 len = nopaged_len - bmax;
37
38 if (nopaged_len > BUF_SIZE_8KiB) {
39
40 des2 = dma_map_single(priv->device, skb->data, bmax,
41 DMA_TO_DEVICE);
42 desc->des2 = cpu_to_le32(des2);
43 if (dma_mapping_error(dev: priv->device, dma_addr: des2))
44 return -1;
45
46 tx_q->tx_skbuff_dma[entry].buf = des2;
47 tx_q->tx_skbuff_dma[entry].len = bmax;
48 tx_q->tx_skbuff_dma[entry].is_jumbo = true;
49
50 desc->des3 = cpu_to_le32(des2 + BUF_SIZE_4KiB);
51 stmmac_prepare_tx_desc(priv, desc, 1, bmax, csum,
52 STMMAC_RING_MODE, 0, false, skb->len);
53 tx_q->tx_skbuff[entry] = NULL;
54 entry = STMMAC_GET_ENTRY(entry, priv->dma_conf.dma_tx_size);
55
56 if (priv->extend_desc)
57 desc = (struct dma_desc *)(tx_q->dma_etx + entry);
58 else
59 desc = tx_q->dma_tx + entry;
60
61 des2 = dma_map_single(priv->device, skb->data + bmax, len,
62 DMA_TO_DEVICE);
63 desc->des2 = cpu_to_le32(des2);
64 if (dma_mapping_error(dev: priv->device, dma_addr: des2))
65 return -1;
66 tx_q->tx_skbuff_dma[entry].buf = des2;
67 tx_q->tx_skbuff_dma[entry].len = len;
68 tx_q->tx_skbuff_dma[entry].is_jumbo = true;
69
70 desc->des3 = cpu_to_le32(des2 + BUF_SIZE_4KiB);
71 stmmac_prepare_tx_desc(priv, desc, 0, len, csum,
72 STMMAC_RING_MODE, 1, !skb_is_nonlinear(skb),
73 skb->len);
74 } else {
75 des2 = dma_map_single(priv->device, skb->data,
76 nopaged_len, DMA_TO_DEVICE);
77 desc->des2 = cpu_to_le32(des2);
78 if (dma_mapping_error(dev: priv->device, dma_addr: des2))
79 return -1;
80 tx_q->tx_skbuff_dma[entry].buf = des2;
81 tx_q->tx_skbuff_dma[entry].len = nopaged_len;
82 tx_q->tx_skbuff_dma[entry].is_jumbo = true;
83 desc->des3 = cpu_to_le32(des2 + BUF_SIZE_4KiB);
84 stmmac_prepare_tx_desc(priv, desc, 1, nopaged_len, csum,
85 STMMAC_RING_MODE, 0, !skb_is_nonlinear(skb),
86 skb->len);
87 }
88
89 tx_q->cur_tx = entry;
90
91 return entry;
92}
93
94static unsigned int is_jumbo_frm(int len, int enh_desc)
95{
96 unsigned int ret = 0;
97
98 if (len >= BUF_SIZE_4KiB)
99 ret = 1;
100
101 return ret;
102}
103
104static void refill_desc3(struct stmmac_rx_queue *rx_q, struct dma_desc *p)
105{
106 struct stmmac_priv *priv = rx_q->priv_data;
107
108 /* Fill DES3 in case of RING mode */
109 if (priv->dma_conf.dma_buf_sz == BUF_SIZE_16KiB)
110 p->des3 = cpu_to_le32(le32_to_cpu(p->des2) + BUF_SIZE_8KiB);
111}
112
113/* In ring mode we need to fill the desc3 because it is used as buffer */
114static void init_desc3(struct dma_desc *p)
115{
116 p->des3 = cpu_to_le32(le32_to_cpu(p->des2) + BUF_SIZE_8KiB);
117}
118
119static void clean_desc3(struct stmmac_tx_queue *tx_q, struct dma_desc *p)
120{
121 struct stmmac_priv *priv = tx_q->priv_data;
122 unsigned int entry = tx_q->dirty_tx;
123
124 /* des3 is only used for jumbo frames tx or time stamping */
125 if (unlikely(tx_q->tx_skbuff_dma[entry].is_jumbo ||
126 (tx_q->tx_skbuff_dma[entry].last_segment &&
127 !priv->extend_desc && priv->hwts_tx_en)))
128 p->des3 = 0;
129}
130
131static int set_16kib_bfsize(int mtu)
132{
133 int ret = 0;
134 if (unlikely(mtu > BUF_SIZE_8KiB))
135 ret = BUF_SIZE_16KiB;
136 return ret;
137}
138
139const struct stmmac_mode_ops ring_mode_ops = {
140 .is_jumbo_frm = is_jumbo_frm,
141 .jumbo_frm = jumbo_frm,
142 .refill_desc3 = refill_desc3,
143 .init_desc3 = init_desc3,
144 .clean_desc3 = clean_desc3,
145 .set_16kib_bfsize = set_16kib_bfsize,
146};
147

source code of linux/drivers/net/ethernet/stmicro/stmmac/ring_mode.c