macb.c

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/* Mark DMA descriptors from begin up to and not including end as unused */
static void discard_partial_frame(struct macb *bp, unsigned int begin,
				  unsigned int end)
{
	unsigned int frag;

	for (frag = begin; frag != end; frag = NEXT_RX(frag))
		bp->rx_ring[frag].addr &= ~MACB_BIT(RX_USED);
	wmb();

	/*
	 * When this happens, the hardware stats registers for
	 * whatever caused this is updated, so we don't have to record
	 * anything.
	 */
}

static int macb_rx(struct macb *bp, int budget)
{
	int received = 0;
	unsigned int tail = bp->rx_tail;
	int first_frag = -1;

	for (; budget > 0; tail = NEXT_RX(tail)) {
		u32 addr, ctrl;

		rmb();
		addr = bp->rx_ring[tail].addr;
		ctrl = bp->rx_ring[tail].ctrl;

		if (!(addr & MACB_BIT(RX_USED)))
			break;

		if (ctrl & MACB_BIT(RX_SOF)) {
			if (first_frag != -1)
				discard_partial_frame(bp, first_frag, tail);
			first_frag = tail;
		}

		if (ctrl & MACB_BIT(RX_EOF)) {
			int dropped;
			BUG_ON(first_frag == -1);

			dropped = macb_rx_frame(bp, first_frag, tail);
			first_frag = -1;
			if (!dropped) {
				received++;
				budget--;
			}
		}
	}

	if (first_frag != -1)
		bp->rx_tail = first_frag;
	else
		bp->rx_tail = tail;

	return received;
}

static int macb_poll(struct napi_struct *napi, int budget)
{
	struct macb *bp = container_of(napi, struct macb, napi);
	struct net_device *dev = bp->dev;
	int work_done;
	u32 status;

	status = macb_readl(bp, RSR);
	macb_writel(bp, RSR, status);

	work_done = 0;
	if (!status) {
		/*
		 * This may happen if an interrupt was pending before
		 * this function was called last time, and no packets
		 * have been received since.
		 */
		netif_rx_complete(dev, napi);
		goto out;
	}

	dev_dbg(&bp->pdev->dev, "poll: status = %08lx, budget = %d\n",
		(unsigned long)status, budget);

	if (!(status & MACB_BIT(REC))) {
		dev_warn(&bp->pdev->dev,
			 "No RX buffers complete, status = %02lx\n",
			 (unsigned long)status);
		netif_rx_complete(dev, napi);
		goto out;
	}

	work_done = macb_rx(bp, budget);
	if (work_done < budget)
		netif_rx_complete(dev, napi);

	/*
	 * We've done what we can to clean the buffers. Make sure we
	 * get notified when new packets arrive.
	 */
out:
	macb_writel(bp, IER, MACB_RX_INT_FLAGS);

	/* TODO: Handle errors */

	return work_done;
}

static irqreturn_t macb_interrupt(int irq, void *dev_id)
{
	struct net_device *dev = dev_id;
	struct macb *bp = netdev_priv(dev);
	u32 status;

	status = macb_readl(bp, ISR);

	if (unlikely(!status))
		return IRQ_NONE;

	spin_lock(&bp->lock);

	while (status) {
		/* close possible race with dev_close */
		if (unlikely(!netif_running(dev))) {
			macb_writel(bp, IDR, ~0UL);
			break;
		}

		if (status & MACB_RX_INT_FLAGS) {
			if (netif_rx_schedule_prep(dev, &bp->napi)) {
				/*
				 * There's no point taking any more interrupts
				 * until we have processed the buffers
				 */
				macb_writel(bp, IDR, MACB_RX_INT_FLAGS);
				dev_dbg(&bp->pdev->dev,
					"scheduling RX softirq\n");
				__netif_rx_schedule(dev, &bp->napi);
			}
		}

		if (status & (MACB_BIT(TCOMP) | MACB_BIT(ISR_TUND)))
			macb_tx(bp);

		/*
		 * Link change detection isn't possible with RMII, so we'll
		 * add that if/when we get our hands on a full-blown MII PHY.
		 */

		if (status & MACB_BIT(HRESP)) {
			/*
			 * TODO: Reset the hardware, and maybe move the printk
			 * to a lower-priority context as well (work queue?)
			 */
			printk(KERN_ERR "%s: DMA bus error: HRESP not OK\n",
			       dev->name);
		}

		status = macb_readl(bp, ISR);
	}

	spin_unlock(&bp->lock);

	return IRQ_HANDLED;
}

static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct macb *bp = netdev_priv(dev);
	dma_addr_t mapping;
	unsigned int len, entry;
	u32 ctrl;

#ifdef DEBUG
	int i;
	dev_dbg(&bp->pdev->dev,
		"start_xmit: len %u head %p data %p tail %p end %p\n",
		skb->len, skb->head, skb->data,
		skb_tail_pointer(skb), skb_end_pointer(skb));
	dev_dbg(&bp->pdev->dev,
		"data:");
	for (i = 0; i < 16; i++)
		printk(" %02x", (unsigned int)skb->data[i]);
	printk("\n");
#endif

	len = skb->len;
	spin_lock_irq(&bp->lock);

	/* This is a hard error, log it. */
	if (TX_BUFFS_AVAIL(bp) < 1) {
		netif_stop_queue(dev);
		spin_unlock_irq(&bp->lock);
		dev_err(&bp->pdev->dev,
			"BUG! Tx Ring full when queue awake!\n");
		dev_dbg(&bp->pdev->dev, "tx_head = %u, tx_tail = %u\n",
			bp->tx_head, bp->tx_tail);
		return 1;
	}

	entry = bp->tx_head;
	dev_dbg(&bp->pdev->dev, "Allocated ring entry %u\n", entry);
	mapping = dma_map_single(&bp->pdev->dev, skb->data,
				 len, DMA_TO_DEVICE);
	bp->tx_skb[entry].skb = skb;
	bp->tx_skb[entry].mapping = mapping;
	dev_dbg(&bp->pdev->dev, "Mapped skb data %p to DMA addr %08lx\n",
		skb->data, (unsigned long)mapping);

	ctrl = MACB_BF(TX_FRMLEN, len);
	ctrl |= MACB_BIT(TX_LAST);
	if (entry == (TX_RING_SIZE - 1))
		ctrl |= MACB_BIT(TX_WRAP);

	bp->tx_ring[entry].addr = mapping;
	bp->tx_ring[entry].ctrl = ctrl;
	wmb();

	entry = NEXT_TX(entry);
	bp->tx_head = entry;

	macb_writel(bp, NCR, macb_readl(bp, NCR) | MACB_BIT(TSTART));

	if (TX_BUFFS_AVAIL(bp) < 1)
		netif_stop_queue(dev);

	spin_unlock_irq(&bp->lock);

	dev->trans_start = jiffies;

	return 0;
}

static void macb_free_consistent(struct macb *bp)
{
	if (bp->tx_skb) {
		kfree(bp->tx_skb);
		bp->tx_skb = NULL;
	}
	if (bp->rx_ring) {
		dma_free_coherent(&bp->pdev->dev, RX_RING_BYTES,
				  bp->rx_ring, bp->rx_ring_dma);
		bp->rx_ring = NULL;
	}
	if (bp->tx_ring) {
		dma_free_coherent(&bp->pdev->dev, TX_RING_BYTES,
				  bp->tx_ring, bp->tx_ring_dma);
		bp->tx_ring = NULL;
	}
	if (bp->rx_buffers) {
		dma_free_coherent(&bp->pdev->dev,
				  RX_RING_SIZE * RX_BUFFER_SIZE,
				  bp->rx_buffers, bp->rx_buffers_dma);
		bp->rx_buffers = NULL;
	}
}

static int macb_alloc_consistent(struct macb *bp)
{
	int size;

	size = TX_RING_SIZE * sizeof(struct ring_info);
	bp->tx_skb = kmalloc(size, GFP_KERNEL);
	if (!bp->tx_skb)
		goto out_err;

	size = RX_RING_BYTES;
	bp->rx_ring = dma_alloc_coherent(&bp->pdev->dev, size,
					 &bp->rx_ring_dma, GFP_KERNEL);
	if (!bp->rx_ring)
		goto out_err;
	dev_dbg(&bp->pdev->dev,
		"Allocated RX ring of %d bytes at %08lx (mapped %p)\n",
		size, (unsigned long)bp->rx_ring_dma, bp->rx_ring);

	size = TX_RING_BYTES;
	bp->tx_ring = dma_alloc_coherent(&bp->pdev->dev, size,
					 &bp->tx_ring_dma, GFP_KERNEL);
	if (!bp->tx_ring)
		goto out_err;
	dev_dbg(&bp->pdev->dev,
		"Allocated TX ring of %d bytes at %08lx (mapped %p)\n",
		size, (unsigned long)bp->tx_ring_dma, bp->tx_ring);

	size = RX_RING_SIZE * RX_BUFFER_SIZE;
	bp->rx_buffers = dma_alloc_coherent(&bp->pdev->dev, size,
					    &bp->rx_buffers_dma, GFP_KERNEL);
	if (!bp->rx_buffers)
		goto out_err;
	dev_dbg(&bp->pdev->dev,
		"Allocated RX buffers of %d bytes at %08lx (mapped %p)\n",
		size, (unsigned long)bp->rx_buffers_dma, bp->rx_buffers);

	return 0;

out_err:
	macb_free_consistent(bp);
	return -ENOMEM;
}

static void macb_init_rings(struct macb *bp)
{
	int i;
	dma_addr_t addr;

	addr = bp->rx_buffers_dma;
	for (i = 0; i < RX_RING_SIZE; i++) {
		bp->rx_ring[i].addr = addr;
		bp->rx_ring[i].ctrl = 0;
		addr += RX_BUFFER_SIZE;
	}
	bp->rx_ring[RX_RING_SIZE - 1].addr |= MACB_BIT(RX_WRAP);

	for (i = 0; i < TX_RING_SIZE; i++) {
		bp->tx_ring[i].addr = 0;
		bp->tx_ring[i].ctrl = MACB_BIT(TX_USED);
	}
	bp->tx_ring[TX_RING_SIZE - 1].ctrl |= MACB_BIT(TX_WRAP);

	bp->rx_tail = bp->tx_head = bp->tx_tail = 0;
}

static void macb_reset_hw(struct macb *bp)
{
	/* Make sure we have the write buffer for ourselves */
	wmb();

	/*
	 * Disable RX and TX (XXX: Should we halt the transmission
	 * more gracefully?)
	 */
	macb_writel(bp, NCR, 0);

	/* Clear the stats registers (XXX: Update stats first?) */
	macb_writel(bp, NCR, MACB_BIT(CLRSTAT));

	/* Clear all status flags */
	macb_writel(bp, TSR, ~0UL);
	macb_writel(bp, RSR, ~0UL);

	/* Disable all interrupts */
	macb_writel(bp, IDR, ~0UL);
	macb_readl(bp, ISR);
}

static void macb_init_hw(struct macb *bp)
{
	u32 config;

	macb_reset_hw(bp);
	__macb_set_hwaddr(bp);

	config = macb_readl(bp, NCFGR) & MACB_BF(CLK, -1L);
	config |= MACB_BIT(PAE);		/* PAuse Enable */
	config |= MACB_BIT(DRFCS);		/* Discard Rx FCS */
	if (bp->dev->flags & IFF_PROMISC)
		config |= MACB_BIT(CAF);	/* Copy All Frames */
	if (!(bp->dev->flags & IFF_BROADCAST))
		config |= MACB_BIT(NBC);	/* No BroadCast */
	macb_writel(bp, NCFGR, config);

	/* Initialize TX and RX buffers */
	macb_writel(bp, RBQP, bp->rx_ring_dma);
	macb_writel(bp, TBQP, bp->tx_ring_dma);

	/* Enable TX and RX */
	macb_writel(bp, NCR, MACB_BIT(RE) | MACB_BIT(TE) | MACB_BIT(MPE));

	/* Enable interrupts */
	macb_writel(bp, IER, (MACB_BIT(RCOMP)
			      | MACB_BIT(RXUBR)
			      | MACB_BIT(ISR_TUND)
			      | MACB_BIT(ISR_RLE)
			      | MACB_BIT(TXERR)
			      | MACB_BIT(TCOMP)
			      | MACB_BIT(ISR_ROVR)
			      | MACB_BIT(HRESP)));

}

/*
 * The hash address register is 64 bits long and takes up two
 * locations in the memory map.  The least significant bits are stored
 * in EMAC_HSL and the most significant bits in EMAC_HSH.
 *
 * The unicast hash enable and the multicast hash enable bits in the
 * network configuration register enable the reception of hash matched
 * frames. The destination address is reduced to a 6 bit index into
 * the 64 bit hash register using the following hash function.  The
 * hash function is an exclusive or of every sixth bit of the
 * destination address.
 *
 * hi[5] = da[5] ^ da[11] ^ da[17] ^ da[23] ^ da[29] ^ da[35] ^ da[41] ^ da[47]
 * hi[4] = da[4] ^ da[10] ^ da[16] ^ da[22] ^ da[28] ^ da[34] ^ da[40] ^ da[46]
 * hi[3] = da[3] ^ da[09] ^ da[15] ^ da[21] ^ da[27] ^ da[33] ^ da[39] ^ da[45]
 * hi[2] = da[2] ^ da[08] ^ da[14] ^ da[20] ^ da[26] ^ da[32] ^ da[38] ^ da[44]
 * hi[1] = da[1] ^ da[07] ^ da[13] ^ da[19] ^ da[25] ^ da[31] ^ da[37] ^ da[43]
 * hi[0] = da[0] ^ da[06] ^ da[12] ^ da[18] ^ da[24] ^ da[30] ^ da[36] ^ da[42]
 *
 * da[0] represents the least significant bit of the first byte
 * received, that is, the multicast/unicast indicator, and da[47]
 * represents the most significant bit of the last byte received.  If
 * the hash index, hi[n], points to a bit that is set in the hash
 * register then the frame will be matched according to whether the
 * frame is multicast or unicast.  A multicast match will be signalled
 * if the multicast hash enable bit is set, da[0] is 1 and the hash
 * index points to a bit set in the hash register.  A unicast match
 * will be signalled if the unicast hash enable bit is set, da[0] is 0
 * and the hash index points to a bit set in the hash register.  To
 * receive all multicast frames, the hash register should be set with
 * all ones and the multicast hash enable bit should be set in the
 * network configuration register.
 */

static inline int hash_bit_value(int bitnr, __u8 *addr)
{
	if (addr[bitnr / 8] & (1 << (bitnr % 8)))
		return 1;
	return 0;
}

/*
 * Return the hash index value for the specified address.
 */
static int hash_get_index(__u8 *addr)
{
	int i, j, bitval;
	int hash_index = 0;

	for (j = 0; j < 6; j++) {
		for (i = 0, bitval = 0; i < 8; i++)
			bitval ^= hash_bit_value(i*6 + j, addr);