bgmac.c

/*
 * Driver for (BCM4706)? GBit MAC core on BCMA bus.
 *
 * Copyright (C) 2012 Rafał Miłecki <zajec5@gmail.com>
 *
 * Licensed under the GNU/GPL. See COPYING for details.
 */


#define pr_fmt(fmt)		KBUILD_MODNAME ": " fmt

#include <linux/bcma/bcma.h>
#include <linux/etherdevice.h>
#include <linux/interrupt.h>
#include <linux/bcm47xx_nvram.h>
#include <linux/phy.h>
#include <linux/phy_fixed.h>
#include <net/dsa.h>
#include "bgmac.h"

static bool bgmac_wait_value(struct bgmac *bgmac, u16 reg, u32 mask,
			     u32 value, int timeout)
{
	u32 val;
	int i;

	for (i = 0; i < timeout / 10; i++) {
		val = bgmac_read(bgmac, reg);
		if ((val & mask) == value)
			return true;
		udelay(10);
	}
	dev_err(bgmac->dev, "Timeout waiting for reg 0x%X\n", reg);
	return false;
}

/**************************************************
 * DMA
 **************************************************/

static void bgmac_dma_tx_reset(struct bgmac *bgmac, struct bgmac_dma_ring *ring)
{
	u32 val;
	int i;

	if (!ring->mmio_base)
		return;

	/* Suspend DMA TX ring first.
	 * bgmac_wait_value doesn't support waiting for any of few values, so
	 * implement whole loop here.
	 */
	bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_CTL,
		    BGMAC_DMA_TX_SUSPEND);
	for (i = 0; i < 10000 / 10; i++) {
		val = bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_TX_STATUS);
		val &= BGMAC_DMA_TX_STAT;
		if (val == BGMAC_DMA_TX_STAT_DISABLED ||
		    val == BGMAC_DMA_TX_STAT_IDLEWAIT ||
		    val == BGMAC_DMA_TX_STAT_STOPPED) {
			i = 0;
			break;
		}
		udelay(10);
	}
	if (i)
		dev_err(bgmac->dev, "Timeout suspending DMA TX ring 0x%X (BGMAC_DMA_TX_STAT: 0x%08X)\n",
			ring->mmio_base, val);

	/* Remove SUSPEND bit */
	bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_CTL, 0);
	if (!bgmac_wait_value(bgmac,
			      ring->mmio_base + BGMAC_DMA_TX_STATUS,
			      BGMAC_DMA_TX_STAT, BGMAC_DMA_TX_STAT_DISABLED,
			      10000)) {
		dev_warn(bgmac->dev, "DMA TX ring 0x%X wasn't disabled on time, waiting additional 300us\n",
			 ring->mmio_base);
		udelay(300);
		val = bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_TX_STATUS);
		if ((val & BGMAC_DMA_TX_STAT) != BGMAC_DMA_TX_STAT_DISABLED)
			dev_err(bgmac->dev, "Reset of DMA TX ring 0x%X failed\n",
				ring->mmio_base);
	}
}

static void bgmac_dma_tx_enable(struct bgmac *bgmac,
				struct bgmac_dma_ring *ring)
{
	u32 ctl;

	ctl = bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_TX_CTL);
	if (bgmac->feature_flags & BGMAC_FEAT_TX_MASK_SETUP) {
		ctl &= ~BGMAC_DMA_TX_BL_MASK;
		ctl |= BGMAC_DMA_TX_BL_128 << BGMAC_DMA_TX_BL_SHIFT;

		ctl &= ~BGMAC_DMA_TX_MR_MASK;
		ctl |= BGMAC_DMA_TX_MR_2 << BGMAC_DMA_TX_MR_SHIFT;

		ctl &= ~BGMAC_DMA_TX_PC_MASK;
		ctl |= BGMAC_DMA_TX_PC_16 << BGMAC_DMA_TX_PC_SHIFT;

		ctl &= ~BGMAC_DMA_TX_PT_MASK;
		ctl |= BGMAC_DMA_TX_PT_8 << BGMAC_DMA_TX_PT_SHIFT;
	}
	ctl |= BGMAC_DMA_TX_ENABLE;
	ctl |= BGMAC_DMA_TX_PARITY_DISABLE;
	bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_CTL, ctl);
}

static void
bgmac_dma_tx_add_buf(struct bgmac *bgmac, struct bgmac_dma_ring *ring,
		     int i, int len, u32 ctl0)
{
	struct bgmac_slot_info *slot;
	struct bgmac_dma_desc *dma_desc;
	u32 ctl1;

	if (i == BGMAC_TX_RING_SLOTS - 1)
		ctl0 |= BGMAC_DESC_CTL0_EOT;

	ctl1 = len & BGMAC_DESC_CTL1_LEN;

	slot = &ring->slots[i];
	dma_desc = &ring->cpu_base[i];
	dma_desc->addr_low = cpu_to_le32(lower_32_bits(slot->dma_addr));
	dma_desc->addr_high = cpu_to_le32(upper_32_bits(slot->dma_addr));
	dma_desc->ctl0 = cpu_to_le32(ctl0);
	dma_desc->ctl1 = cpu_to_le32(ctl1);
}

static netdev_tx_t bgmac_dma_tx_add(struct bgmac *bgmac,
				    struct bgmac_dma_ring *ring,
				    struct sk_buff *skb)
{
	struct device *dma_dev = bgmac->dma_dev;
	struct net_device *net_dev = bgmac->net_dev;
	int index = ring->end % BGMAC_TX_RING_SLOTS;
	struct bgmac_slot_info *slot = &ring->slots[index];
	int nr_frags;
	u32 flags;
	int i;

	if (skb->len > BGMAC_DESC_CTL1_LEN) {
		netdev_err(bgmac->net_dev, "Too long skb (%d)\n", skb->len);
		goto err_drop;
	}

	if (skb->ip_summed == CHECKSUM_PARTIAL)
		skb_checksum_help(skb);

	nr_frags = skb_shinfo(skb)->nr_frags;

	/* ring->end - ring->start will return the number of valid slots,
	 * even when ring->end overflows
	 */
	if (ring->end - ring->start + nr_frags + 1 >= BGMAC_TX_RING_SLOTS) {
		netdev_err(bgmac->net_dev, "TX ring is full, queue should be stopped!\n");
		netif_stop_queue(net_dev);
		return NETDEV_TX_BUSY;
	}

	slot->dma_addr = dma_map_single(dma_dev, skb->data, skb_headlen(skb),
					DMA_TO_DEVICE);
	if (unlikely(dma_mapping_error(dma_dev, slot->dma_addr)))
		goto err_dma_head;

	flags = BGMAC_DESC_CTL0_SOF;
	if (!nr_frags)
		flags |= BGMAC_DESC_CTL0_EOF | BGMAC_DESC_CTL0_IOC;

	bgmac_dma_tx_add_buf(bgmac, ring, index, skb_headlen(skb), flags);
	flags = 0;

	for (i = 0; i < nr_frags; i++) {
		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
		int len = skb_frag_size(frag);

		index = (index + 1) % BGMAC_TX_RING_SLOTS;
		slot = &ring->slots[index];
		slot->dma_addr = skb_frag_dma_map(dma_dev, frag, 0,
						  len, DMA_TO_DEVICE);
		if (unlikely(dma_mapping_error(dma_dev, slot->dma_addr)))
			goto err_dma;

		if (i == nr_frags - 1)
			flags |= BGMAC_DESC_CTL0_EOF | BGMAC_DESC_CTL0_IOC;

		bgmac_dma_tx_add_buf(bgmac, ring, index, len, flags);
	}

	slot->skb = skb;
	ring->end += nr_frags + 1;
	netdev_sent_queue(net_dev, skb->len);

	wmb();

	/* Increase ring->end to point empty slot. We tell hardware the first
	 * slot it should *not* read.
	 */
	bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_INDEX,