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bgmac: implement unaligned addressing for DMA rings that support it
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This is important patch for new devices that support unaligned
addressing. That devices suffer from the backward-compatibility bug in
DMA engine. In theory we should be able to use old mechanism, but in
practice DMA address seems to be randomly copied into status register
when hardware reaches end of a ring. This breaks reading slot number
from status register and we can't use DMA anymore.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Rafał Miłecki authored and David S. Miller committed Sep 17, 2013
1 parent 3647268 commit 9900303
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Showing 2 changed files with 30 additions and 10 deletions.
38 changes: 28 additions & 10 deletions drivers/net/ethernet/broadcom/bgmac.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -157,6 +157,7 @@ static netdev_tx_t bgmac_dma_tx_add(struct bgmac *bgmac,
if (++ring->end >= BGMAC_TX_RING_SLOTS)
ring->end = 0;
bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_INDEX,
ring->index_base +
ring->end * sizeof(struct bgmac_dma_desc));

/* Always keep one slot free to allow detecting bugged calls. */
Expand All @@ -181,6 +182,8 @@ static void bgmac_dma_tx_free(struct bgmac *bgmac, struct bgmac_dma_ring *ring)
/* The last slot that hardware didn't consume yet */
empty_slot = bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_TX_STATUS);
empty_slot &= BGMAC_DMA_TX_STATDPTR;
empty_slot -= ring->index_base;
empty_slot &= BGMAC_DMA_TX_STATDPTR;
empty_slot /= sizeof(struct bgmac_dma_desc);

while (ring->start != empty_slot) {
Expand Down Expand Up @@ -274,6 +277,8 @@ static int bgmac_dma_rx_read(struct bgmac *bgmac, struct bgmac_dma_ring *ring,

end_slot = bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_RX_STATUS);
end_slot &= BGMAC_DMA_RX_STATDPTR;
end_slot -= ring->index_base;
end_slot &= BGMAC_DMA_RX_STATDPTR;
end_slot /= sizeof(struct bgmac_dma_desc);

ring->end = end_slot;
Expand Down Expand Up @@ -418,9 +423,6 @@ static int bgmac_dma_alloc(struct bgmac *bgmac)
ring = &bgmac->tx_ring[i];
ring->num_slots = BGMAC_TX_RING_SLOTS;
ring->mmio_base = ring_base[i];
if (bgmac_dma_unaligned(bgmac, ring, BGMAC_DMA_RING_TX))
bgmac_warn(bgmac, "TX on ring 0x%X supports unaligned addressing but this feature is not implemented\n",
ring->mmio_base);

/* Alloc ring of descriptors */
size = ring->num_slots * sizeof(struct bgmac_dma_desc);
Expand All @@ -435,6 +437,13 @@ static int bgmac_dma_alloc(struct bgmac *bgmac)
if (ring->dma_base & 0xC0000000)
bgmac_warn(bgmac, "DMA address using 0xC0000000 bit(s), it may need translation trick\n");

ring->unaligned = bgmac_dma_unaligned(bgmac, ring,
BGMAC_DMA_RING_TX);
if (ring->unaligned)
ring->index_base = lower_32_bits(ring->dma_base);
else
ring->index_base = 0;

/* No need to alloc TX slots yet */
}

Expand All @@ -444,9 +453,6 @@ static int bgmac_dma_alloc(struct bgmac *bgmac)
ring = &bgmac->rx_ring[i];
ring->num_slots = BGMAC_RX_RING_SLOTS;
ring->mmio_base = ring_base[i];
if (bgmac_dma_unaligned(bgmac, ring, BGMAC_DMA_RING_RX))
bgmac_warn(bgmac, "RX on ring 0x%X supports unaligned addressing but this feature is not implemented\n",
ring->mmio_base);

/* Alloc ring of descriptors */
size = ring->num_slots * sizeof(struct bgmac_dma_desc);
Expand All @@ -462,6 +468,13 @@ static int bgmac_dma_alloc(struct bgmac *bgmac)
if (ring->dma_base & 0xC0000000)
bgmac_warn(bgmac, "DMA address using 0xC0000000 bit(s), it may need translation trick\n");

ring->unaligned = bgmac_dma_unaligned(bgmac, ring,
BGMAC_DMA_RING_RX);
if (ring->unaligned)
ring->index_base = lower_32_bits(ring->dma_base);
else
ring->index_base = 0;

/* Alloc RX slots */
for (j = 0; j < ring->num_slots; j++) {
err = bgmac_dma_rx_skb_for_slot(bgmac, &ring->slots[j]);
Expand Down Expand Up @@ -489,12 +502,14 @@ static void bgmac_dma_init(struct bgmac *bgmac)
for (i = 0; i < BGMAC_MAX_TX_RINGS; i++) {
ring = &bgmac->tx_ring[i];

/* We don't implement unaligned addressing, so enable first */
bgmac_dma_tx_enable(bgmac, ring);
if (!ring->unaligned)
bgmac_dma_tx_enable(bgmac, ring);
bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_RINGLO,
lower_32_bits(ring->dma_base));
bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_RINGHI,
upper_32_bits(ring->dma_base));
if (ring->unaligned)
bgmac_dma_tx_enable(bgmac, ring);

ring->start = 0;
ring->end = 0; /* Points the slot that should *not* be read */
Expand All @@ -505,12 +520,14 @@ static void bgmac_dma_init(struct bgmac *bgmac)

ring = &bgmac->rx_ring[i];

/* We don't implement unaligned addressing, so enable first */
bgmac_dma_rx_enable(bgmac, ring);
if (!ring->unaligned)
bgmac_dma_rx_enable(bgmac, ring);
bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_RX_RINGLO,
lower_32_bits(ring->dma_base));
bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_RX_RINGHI,
upper_32_bits(ring->dma_base));
if (ring->unaligned)
bgmac_dma_rx_enable(bgmac, ring);

for (j = 0, dma_desc = ring->cpu_base; j < ring->num_slots;
j++, dma_desc++) {
Expand All @@ -531,6 +548,7 @@ static void bgmac_dma_init(struct bgmac *bgmac)
}

bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_RX_INDEX,
ring->index_base +
ring->num_slots * sizeof(struct bgmac_dma_desc));

ring->start = 0;
Expand Down
2 changes: 2 additions & 0 deletions drivers/net/ethernet/broadcom/bgmac.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -384,6 +384,8 @@ struct bgmac_dma_ring {
u16 mmio_base;
struct bgmac_dma_desc *cpu_base;
dma_addr_t dma_base;
u32 index_base; /* Used for unaligned rings only, otherwise 0 */
bool unaligned;

struct bgmac_slot_info slots[BGMAC_RX_RING_SLOTS];
};
Expand Down

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