linux/drivers/net/ethernet/stmicro/stmmac/ring_mode.c

// SPDX-License-Identifier: GPL-2.0-only
/*******************************************************************************
  Specialised functions for managing Ring mode

  Copyright(C) 2011  STMicroelectronics Ltd

  It defines all the functions used to handle the normal/enhanced
  descriptors in case of the DMA is configured to work in chained or
  in ring mode.


  Author: Giuseppe Cavallaro <peppe.cavallaro@st.com>
*******************************************************************************/

#include "stmmac.h"

static int jumbo_frm(struct stmmac_tx_queue *tx_q, struct sk_buff *skb,
		     int csum)
{
	unsigned int nopaged_len = skb_headlen(skb);
	struct stmmac_priv *priv = tx_q->priv_data;
	unsigned int entry = tx_q->cur_tx;
	unsigned int bmax, len, des2;
	struct dma_desc *desc;

	if (priv->extend_desc)
		desc = (struct dma_desc *)(tx_q->dma_etx + entry);
	else
		desc = tx_q->dma_tx + entry;

	if (priv->plat->enh_desc)
		bmax = BUF_SIZE_8KiB;
	else
		bmax = BUF_SIZE_2KiB;

	len = nopaged_len - bmax;

	if (nopaged_len > BUF_SIZE_8KiB) {

		des2 = dma_map_single(priv->device, skb->data, bmax,
				      DMA_TO_DEVICE);
		desc->des2 = cpu_to_le32(des2);
		if (dma_mapping_error(priv->device, des2))
			return -1;

		tx_q->tx_skbuff_dma[entry].buf = des2;
		tx_q->tx_skbuff_dma[entry].len = bmax;
		tx_q->tx_skbuff_dma[entry].is_jumbo = true;

		desc->des3 = cpu_to_le32(des2 + BUF_SIZE_4KiB);
		stmmac_prepare_tx_desc(priv, desc, 1, bmax, csum,
				STMMAC_RING_MODE, 0, false, skb->len);
		tx_q->tx_skbuff[entry] = NULL;
		entry = STMMAC_GET_ENTRY(entry, priv->dma_conf.dma_tx_size);

		if (priv->extend_desc)
			desc = (struct dma_desc *)(tx_q->dma_etx + entry);
		else
			desc = tx_q->dma_tx + entry;

		des2 = dma_map_single(priv->device, skb->data + bmax, len,
				      DMA_TO_DEVICE);
		desc->des2 = cpu_to_le32(des2);
		if (dma_mapping_error(priv->device, des2))
			return -1;
		tx_q->tx_skbuff_dma[entry].buf = des2;
		tx_q->tx_skbuff_dma[entry].len = len;
		tx_q->tx_skbuff_dma[entry].is_jumbo = true;

		desc->des3 = cpu_to_le32(des2 + BUF_SIZE_4KiB);
		stmmac_prepare_tx_desc(priv, desc, 0, len, csum,
				STMMAC_RING_MODE, 1, !skb_is_nonlinear(skb),
				skb->len);
	} else {
		des2 = dma_map_single(priv->device, skb->data,
				      nopaged_len, DMA_TO_DEVICE);
		desc->des2 = cpu_to_le32(des2);
		if (dma_mapping_error(priv->device, des2))
			return -1;
		tx_q->tx_skbuff_dma[entry].buf = des2;
		tx_q->tx_skbuff_dma[entry].len = nopaged_len;
		tx_q->tx_skbuff_dma[entry].is_jumbo = true;
		desc->des3 = cpu_to_le32(des2 + BUF_SIZE_4KiB);
		stmmac_prepare_tx_desc(priv, desc, 1, nopaged_len, csum,
				STMMAC_RING_MODE, 0, !skb_is_nonlinear(skb),
				skb->len);
	}

	tx_q->cur_tx = entry;

	return entry;
}

static bool is_jumbo_frm(unsigned int len, bool enh_desc)
{
	return len >= BUF_SIZE_4KiB;
}

static void refill_desc3(struct stmmac_rx_queue *rx_q, struct dma_desc *p)
{
	struct stmmac_priv *priv = rx_q->priv_data;

	/* Fill DES3 in case of RING mode */
	if (priv->dma_conf.dma_buf_sz == BUF_SIZE_16KiB)
		p->des3 = cpu_to_le32(le32_to_cpu(p->des2) + BUF_SIZE_8KiB);
}

/* In ring mode we need to fill the desc3 because it is used as buffer */
static void init_desc3(struct dma_desc *p)
{
	p->des3 = cpu_to_le32(le32_to_cpu(p->des2) + BUF_SIZE_8KiB);
}

static void clean_desc3(struct stmmac_tx_queue *tx_q, struct dma_desc *p)
{
	struct stmmac_priv *priv = tx_q->priv_data;
	unsigned int entry = tx_q->dirty_tx;

	/* des3 is only used for jumbo frames tx or time stamping */
	if (unlikely(tx_q->tx_skbuff_dma[entry].is_jumbo ||
		     (tx_q->tx_skbuff_dma[entry].last_segment &&
		      !priv->extend_desc && priv->hwts_tx_en)))
		p->des3 = 0;
}

static int set_16kib_bfsize(int mtu)
{
	int ret = 0;
	if (unlikely(mtu > BUF_SIZE_8KiB))
		ret = BUF_SIZE_16KiB;
	return ret;
}

const struct stmmac_mode_ops ring_mode_ops = {
	.is_jumbo_frm = is_jumbo_frm,
	.jumbo_frm = jumbo_frm,
	.refill_desc3 = refill_desc3,
	.init_desc3 = init_desc3,
	.clean_desc3 = clean_desc3,
	.set_16kib_bfsize = set_16kib_bfsize,
};