sfc: Replace some literal constants with EFX_PAGE_SIZE/EFX_BUF_SIZE

The 'page size' for PCIe DMA, i.e. the alignment of boundaries at
which DMA must be broken, is 4KB.  Name this value as EFX_PAGE_SIZE
and use it in efx_max_tx_len().  Redefine EFX_BUF_SIZE as
EFX_PAGE_SIZE since its value is also a result of that requirement,
and use it in efx_init_special_buffer().

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

3 files changed, 7 insertions, 5 deletions

diff --git a/drivers/net/ethernet/sfc/nic.c b/drivers/net/ethernet/sfc/nic.c
index a43d1ca270c0..dd50c4f73a9d 100644
--- a/drivers/net/ethernet/sfc/nic.c
+++ b/drivers/net/ethernet/sfc/nic.c
@@ -54,9 +54,6 @@
 #define EFX_FLUSH_INTERVAL 10
 #define EFX_FLUSH_POLL_COUNT 100
 
-/* Size and alignment of special buffers (4KB) */
-#define EFX_BUF_SIZE 4096
-
 /* Depth of RX flush request fifo */
 #define EFX_RX_FLUSH_COUNT 4
 
@@ -196,7 +193,7 @@ efx_init_special_buffer(struct efx_nic *efx, struct efx_special_buffer *buffer)
         /* Write buffer descriptors to NIC */
         for (i = 0; i < buffer->entries; i++) {
                 index = buffer->index + i;
-                dma_addr = buffer->dma_addr + (i * 4096);
+                dma_addr = buffer->dma_addr + (i * EFX_BUF_SIZE);
                 netif_dbg(efx, probe, efx->net_dev,
                           "mapping special buffer %d at %llx\n",
                           index, (unsigned long long)dma_addr);
diff --git a/drivers/net/ethernet/sfc/nic.h b/drivers/net/ethernet/sfc/nic.h
index 905a1877d603..4f9d18ac92fe 100644
--- a/drivers/net/ethernet/sfc/nic.h
+++ b/drivers/net/ethernet/sfc/nic.h
@@ -65,6 +65,11 @@ enum {
 #define FALCON_GMAC_LOOPBACKS                   \
         (1 << LOOPBACK_GMAC)
 
+/* Alignment of PCIe DMA boundaries (4KB) */
+#define EFX_PAGE_SIZE   4096
+/* Size and alignment of buffer table entries (same) */
+#define EFX_BUF_SIZE    EFX_PAGE_SIZE
+
 /**
  * struct falcon_board_type - board operations and type information
  * @id: Board type id, as found in NVRAM
diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
index 5cb81fa3fcbd..a096e287e95f 100644
--- a/drivers/net/ethernet/sfc/tx.c
+++ b/drivers/net/ethernet/sfc/tx.c
@@ -110,7 +110,7 @@ efx_max_tx_len(struct efx_nic *efx, dma_addr_t dma_addr)
          * little benefit from using descriptors that cross those
          * boundaries and we keep things simple by not doing so.
          */
-        unsigned len = (~dma_addr & 0xfff) + 1;
+        unsigned len = (~dma_addr & (EFX_PAGE_SIZE - 1)) + 1;
 
         /* Work around hardware bug for unaligned buffers. */
         if (EFX_WORKAROUND_5391(efx) && (dma_addr & 0xf))