target/linux/brcm47xx/patches-3.10/712-bgmac_implement_unaligned_addressing.patch

   1 bgmac: implement unaligned addressing for DMA rings that support it
   2
   3 This is important patch for new devices that support unaligned
   4 addressing. That devices suffer from the backward-compatibility bug in
   5 DMA engine. In theory we should be able to use old mechanism, but in
   6 practice DMA address seems to be randomly copied into status register
   7 when hardware reaches end of a ring. This breaks reading slot number
   8 from status register and we can't use DMA anymore.
   9
  10 Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
  11
  12 --- a/drivers/net/ethernet/broadcom/bgmac.c
  13 +++ b/drivers/net/ethernet/broadcom/bgmac.c
  14 @@ -157,6 +157,7 @@ static netdev_tx_t bgmac_dma_tx_add(stru
  15         if (++ring->end >= BGMAC_TX_RING_SLOTS)
  16                 ring->end = 0;
  17         bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_INDEX,
  18 +                   ring->index_base +
  19                     ring->end * sizeof(struct bgmac_dma_desc));
  20
  21         /* Always keep one slot free to allow detecting bugged calls. */
  22 @@ -181,6 +182,8 @@ static void bgmac_dma_tx_free(struct bgm
  23         /* The last slot that hardware didn't consume yet */
  24         empty_slot = bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_TX_STATUS);
  25         empty_slot &= BGMAC_DMA_TX_STATDPTR;
  26 +       empty_slot -= ring->index_base;
  27 +       empty_slot &= BGMAC_DMA_TX_STATDPTR;
  28         empty_slot /= sizeof(struct bgmac_dma_desc);
  29
  30         while (ring->start != empty_slot) {
  31 @@ -274,6 +277,8 @@ static int bgmac_dma_rx_read(struct bgma
  32
  33         end_slot = bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_RX_STATUS);
  34         end_slot &= BGMAC_DMA_RX_STATDPTR;
  35 +       end_slot -= ring->index_base;
  36 +       end_slot &= BGMAC_DMA_RX_STATDPTR;
  37         end_slot /= sizeof(struct bgmac_dma_desc);
  38
  39         ring->end = end_slot;
  40 @@ -418,9 +423,6 @@ static int bgmac_dma_alloc(struct bgmac
  41                 ring = &bgmac->tx_ring[i];
  42                 ring->num_slots = BGMAC_TX_RING_SLOTS;
  43                 ring->mmio_base = ring_base[i];
  44 -               if (bgmac_dma_unaligned(bgmac, ring, BGMAC_DMA_RING_TX))
  45 -                       bgmac_warn(bgmac, "TX on ring 0x%X supports unaligned addressing but this feature is not implemented\n",
  46 -                                  ring->mmio_base);
  47
  48                 /* Alloc ring of descriptors */
  49                 size = ring->num_slots * sizeof(struct bgmac_dma_desc);
  50 @@ -435,6 +437,13 @@ static int bgmac_dma_alloc(struct bgmac
  51                 if (ring->dma_base & 0xC0000000)
  52                         bgmac_warn(bgmac, "DMA address using 0xC0000000 bit(s), it may need translation trick\n");
  53
  54 +               ring->unaligned = bgmac_dma_unaligned(bgmac, ring,
  55 +                                                     BGMAC_DMA_RING_TX);
  56 +               if (ring->unaligned)
  57 +                       ring->index_base = lower_32_bits(ring->dma_base);
  58 +               else
  59 +                       ring->index_base = 0;
  60 +
  61                 /* No need to alloc TX slots yet */
  62         }
  63
  64 @@ -444,9 +453,6 @@ static int bgmac_dma_alloc(struct bgmac
  65                 ring = &bgmac->rx_ring[i];
  66                 ring->num_slots = BGMAC_RX_RING_SLOTS;
  67                 ring->mmio_base = ring_base[i];
  68 -               if (bgmac_dma_unaligned(bgmac, ring, BGMAC_DMA_RING_RX))
  69 -                       bgmac_warn(bgmac, "RX on ring 0x%X supports unaligned addressing but this feature is not implemented\n",
  70 -                                  ring->mmio_base);
  71
  72                 /* Alloc ring of descriptors */
  73                 size = ring->num_slots * sizeof(struct bgmac_dma_desc);
  74 @@ -462,6 +468,13 @@ static int bgmac_dma_alloc(struct bgmac
  75                 if (ring->dma_base & 0xC0000000)
  76                         bgmac_warn(bgmac, "DMA address using 0xC0000000 bit(s), it may need translation trick\n");
  77
  78 +               ring->unaligned = bgmac_dma_unaligned(bgmac, ring,
  79 +                                                     BGMAC_DMA_RING_RX);
  80 +               if (ring->unaligned)
  81 +                       ring->index_base = lower_32_bits(ring->dma_base);
  82 +               else
  83 +                       ring->index_base = 0;
  84 +
  85                 /* Alloc RX slots */
  86                 for (j = 0; j < ring->num_slots; j++) {
  87                         err = bgmac_dma_rx_skb_for_slot(bgmac, &ring->slots[j]);
  88 @@ -489,12 +502,14 @@ static void bgmac_dma_init(struct bgmac
  89         for (i = 0; i < BGMAC_MAX_TX_RINGS; i++) {
  90                 ring = &bgmac->tx_ring[i];
  91
  92 -               /* We don't implement unaligned addressing, so enable first */
  93 -               bgmac_dma_tx_enable(bgmac, ring);
  94 +               if (!ring->unaligned)
  95 +                       bgmac_dma_tx_enable(bgmac, ring);
  96                 bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_RINGLO,
  97                             lower_32_bits(ring->dma_base));
  98                 bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_TX_RINGHI,
  99                             upper_32_bits(ring->dma_base));
 100 +               if (ring->unaligned)
 101 +                       bgmac_dma_tx_enable(bgmac, ring);
 102
 103                 ring->start = 0;
 104                 ring->end = 0;  /* Points the slot that should *not* be read */
 105 @@ -505,12 +520,14 @@ static void bgmac_dma_init(struct bgmac
 106
 107                 ring = &bgmac->rx_ring[i];
 108
 109 -               /* We don't implement unaligned addressing, so enable first */
 110 -               bgmac_dma_rx_enable(bgmac, ring);
 111 +               if (!ring->unaligned)
 112 +                       bgmac_dma_rx_enable(bgmac, ring);
 113                 bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_RX_RINGLO,
 114                             lower_32_bits(ring->dma_base));
 115                 bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_RX_RINGHI,
 116                             upper_32_bits(ring->dma_base));
 117 +               if (ring->unaligned)
 118 +                       bgmac_dma_rx_enable(bgmac, ring);
 119
 120                 for (j = 0, dma_desc = ring->cpu_base; j < ring->num_slots;
 121                      j++, dma_desc++) {
 122 @@ -531,6 +548,7 @@ static void bgmac_dma_init(struct bgmac
 123                 }
 124
 125                 bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_RX_INDEX,
 126 +                           ring->index_base +
 127                             ring->num_slots * sizeof(struct bgmac_dma_desc));
 128
 129                 ring->start = 0;
 130 --- a/drivers/net/ethernet/broadcom/bgmac.h
 131 +++ b/drivers/net/ethernet/broadcom/bgmac.h
 132 @@ -384,6 +384,8 @@ struct bgmac_dma_ring {
 133         u16 mmio_base;
 134         struct bgmac_dma_desc *cpu_base;
 135         dma_addr_t dma_base;
 136 +       u32 index_base; /* Used for unaligned rings only, otherwise 0 */
 137 +       bool unaligned;
 138
 139         struct bgmac_slot_info slots[BGMAC_RX_RING_SLOTS];
 140  };