1 /*******************************************************************************
2   Specialised functions for managing Chained mode
3 
4   Copyright(C) 2011  STMicroelectronics Ltd
5 
6   It defines all the functions used to handle the normal/enhanced
7   descriptors in case of the DMA is configured to work in chained or
8   in ring mode.
9 
10   This program is free software; you can redistribute it and/or modify it
11   under the terms and conditions of the GNU General Public License,
12   version 2, as published by the Free Software Foundation.
13 
14   This program is distributed in the hope it will be useful, but WITHOUT
15   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
16   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
17   more details.
18 
19   The full GNU General Public License is included in this distribution in
20   the file called "COPYING".
21 
22   Author: Giuseppe Cavallaro <peppe.cavallaro@st.com>
23 *******************************************************************************/
24 
25 #include "stmmac.h"
26 
27 static int jumbo_frm(void *p, struct sk_buff *skb, int csum)
28 {
29 	struct stmmac_tx_queue *tx_q = (struct stmmac_tx_queue *)p;
30 	unsigned int nopaged_len = skb_headlen(skb);
31 	struct stmmac_priv *priv = tx_q->priv_data;
32 	unsigned int entry = tx_q->cur_tx;
33 	unsigned int bmax, des2;
34 	unsigned int i = 1, len;
35 	struct dma_desc *desc;
36 
37 	desc = tx_q->dma_tx + entry;
38 
39 	if (priv->plat->enh_desc)
40 		bmax = BUF_SIZE_8KiB;
41 	else
42 		bmax = BUF_SIZE_2KiB;
43 
44 	len = nopaged_len - bmax;
45 
46 	des2 = dma_map_single(priv->device, skb->data,
47 			      bmax, DMA_TO_DEVICE);
48 	desc->des2 = cpu_to_le32(des2);
49 	if (dma_mapping_error(priv->device, des2))
50 		return -1;
51 	tx_q->tx_skbuff_dma[entry].buf = des2;
52 	tx_q->tx_skbuff_dma[entry].len = bmax;
53 	/* do not close the descriptor and do not set own bit */
54 	stmmac_prepare_tx_desc(priv, desc, 1, bmax, csum, STMMAC_CHAIN_MODE,
55 			0, false, skb->len);
56 
57 	while (len != 0) {
58 		tx_q->tx_skbuff[entry] = NULL;
59 		entry = STMMAC_GET_ENTRY(entry, DMA_TX_SIZE);
60 		desc = tx_q->dma_tx + entry;
61 
62 		if (len > bmax) {
63 			des2 = dma_map_single(priv->device,
64 					      (skb->data + bmax * i),
65 					      bmax, DMA_TO_DEVICE);
66 			desc->des2 = cpu_to_le32(des2);
67 			if (dma_mapping_error(priv->device, des2))
68 				return -1;
69 			tx_q->tx_skbuff_dma[entry].buf = des2;
70 			tx_q->tx_skbuff_dma[entry].len = bmax;
71 			stmmac_prepare_tx_desc(priv, desc, 0, bmax, csum,
72 					STMMAC_CHAIN_MODE, 1, false, skb->len);
73 			len -= bmax;
74 			i++;
75 		} else {
76 			des2 = dma_map_single(priv->device,
77 					      (skb->data + bmax * i), len,
78 					      DMA_TO_DEVICE);
79 			desc->des2 = cpu_to_le32(des2);
80 			if (dma_mapping_error(priv->device, des2))
81 				return -1;
82 			tx_q->tx_skbuff_dma[entry].buf = des2;
83 			tx_q->tx_skbuff_dma[entry].len = len;
84 			/* last descriptor can be set now */
85 			stmmac_prepare_tx_desc(priv, desc, 0, len, csum,
86 					STMMAC_CHAIN_MODE, 1, true, skb->len);
87 			len = 0;
88 		}
89 	}
90 
91 	tx_q->cur_tx = entry;
92 
93 	return entry;
94 }
95 
96 static unsigned int is_jumbo_frm(int len, int enh_desc)
97 {
98 	unsigned int ret = 0;
99 
100 	if ((enh_desc && (len > BUF_SIZE_8KiB)) ||
101 	    (!enh_desc && (len > BUF_SIZE_2KiB))) {
102 		ret = 1;
103 	}
104 
105 	return ret;
106 }
107 
108 static void init_dma_chain(void *des, dma_addr_t phy_addr,
109 				  unsigned int size, unsigned int extend_desc)
110 {
111 	/*
112 	 * In chained mode the des3 points to the next element in the ring.
113 	 * The latest element has to point to the head.
114 	 */
115 	int i;
116 	dma_addr_t dma_phy = phy_addr;
117 
118 	if (extend_desc) {
119 		struct dma_extended_desc *p = (struct dma_extended_desc *)des;
120 		for (i = 0; i < (size - 1); i++) {
121 			dma_phy += sizeof(struct dma_extended_desc);
122 			p->basic.des3 = cpu_to_le32((unsigned int)dma_phy);
123 			p++;
124 		}
125 		p->basic.des3 = cpu_to_le32((unsigned int)phy_addr);
126 
127 	} else {
128 		struct dma_desc *p = (struct dma_desc *)des;
129 		for (i = 0; i < (size - 1); i++) {
130 			dma_phy += sizeof(struct dma_desc);
131 			p->des3 = cpu_to_le32((unsigned int)dma_phy);
132 			p++;
133 		}
134 		p->des3 = cpu_to_le32((unsigned int)phy_addr);
135 	}
136 }
137 
138 static void refill_desc3(void *priv_ptr, struct dma_desc *p)
139 {
140 	struct stmmac_rx_queue *rx_q = (struct stmmac_rx_queue *)priv_ptr;
141 	struct stmmac_priv *priv = rx_q->priv_data;
142 
143 	if (priv->hwts_rx_en && !priv->extend_desc)
144 		/* NOTE: Device will overwrite des3 with timestamp value if
145 		 * 1588-2002 time stamping is enabled, hence reinitialize it
146 		 * to keep explicit chaining in the descriptor.
147 		 */
148 		p->des3 = cpu_to_le32((unsigned int)(rx_q->dma_rx_phy +
149 				      (((rx_q->dirty_rx) + 1) %
150 				       DMA_RX_SIZE) *
151 				      sizeof(struct dma_desc)));
152 }
153 
154 static void clean_desc3(void *priv_ptr, struct dma_desc *p)
155 {
156 	struct stmmac_tx_queue *tx_q = (struct stmmac_tx_queue *)priv_ptr;
157 	struct stmmac_priv *priv = tx_q->priv_data;
158 	unsigned int entry = tx_q->dirty_tx;
159 
160 	if (tx_q->tx_skbuff_dma[entry].last_segment && !priv->extend_desc &&
161 	    priv->hwts_tx_en)
162 		/* NOTE: Device will overwrite des3 with timestamp value if
163 		 * 1588-2002 time stamping is enabled, hence reinitialize it
164 		 * to keep explicit chaining in the descriptor.
165 		 */
166 		p->des3 = cpu_to_le32((unsigned int)((tx_q->dma_tx_phy +
167 				      ((tx_q->dirty_tx + 1) % DMA_TX_SIZE))
168 				      * sizeof(struct dma_desc)));
169 }
170 
171 const struct stmmac_mode_ops chain_mode_ops = {
172 	.init = init_dma_chain,
173 	.is_jumbo_frm = is_jumbo_frm,
174 	.jumbo_frm = jumbo_frm,
175 	.refill_desc3 = refill_desc3,
176 	.clean_desc3 = clean_desc3,
177 };
178