sfc: Extend struct efx_tx_buffer to allow pushing option descriptors

The TX path firmware for EF10 supports 'option descriptors' to control
offloads and various other features.  Add a flag and field for these
in struct efx_tx_buffer, and don't treat them as DMA descriptors on
completion.

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

3 files changed, 11 insertions, 2 deletions

diff --git a/drivers/net/ethernet/sfc/farch.c b/drivers/net/ethernet/sfc/farch.c
index 842f92e45517..65073aac3c80 100644
--- a/drivers/net/ethernet/sfc/farch.c
+++ b/drivers/net/ethernet/sfc/farch.c
@@ -325,6 +325,8 @@ void efx_farch_tx_write(struct efx_tx_queue *tx_queue)
                 txd = efx_tx_desc(tx_queue, write_ptr);
                 ++tx_queue->write_count;
 
+                EFX_BUG_ON_PARANOID(buffer->flags & EFX_TX_BUF_OPTION);
+
                 /* Create TX descriptor ring entry */
                 BUILD_BUG_ON(EFX_TX_BUF_CONT != 1);
                 EFX_POPULATE_QWORD_4(*txd,
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index c9b6f2dcb539..d1aa5dcec963 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -135,6 +135,7 @@ struct efx_special_buffer {
  *      freed when descriptor completes
  * @heap_buf: When @flags & %EFX_TX_BUF_HEAP, the associated heap buffer to be
  *      freed when descriptor completes.
+ * @option: When @flags & %EFX_TX_BUF_OPTION, a NIC-specific option descriptor.
  * @dma_addr: DMA address of the fragment.
  * @flags: Flags for allocation and DMA mapping type
  * @len: Length of this fragment.
@@ -146,7 +147,10 @@ struct efx_tx_buffer {
                 const struct sk_buff *skb;
                 void *heap_buf;
         };
-        dma_addr_t dma_addr;
+        union {
+                efx_qword_t option;
+                dma_addr_t dma_addr;
+        };
         unsigned short flags;
         unsigned short len;
         unsigned short unmap_len;
@@ -155,6 +159,7 @@ struct efx_tx_buffer {
 #define EFX_TX_BUF_SKB          2       /* buffer is last part of skb */
 #define EFX_TX_BUF_HEAP         4       /* buffer was allocated with kmalloc() */
 #define EFX_TX_BUF_MAP_SINGLE   8       /* buffer was mapped with dma_map_single() */
+#define EFX_TX_BUF_OPTION       0x10    /* empty buffer for option descriptor */
 
 /**
  * struct efx_tx_queue - An Efx TX queue
diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
index 85ee647b28ad..82075f9f02e6 100644
--- a/drivers/net/ethernet/sfc/tx.c
+++ b/drivers/net/ethernet/sfc/tx.c
@@ -306,7 +306,9 @@ static void efx_dequeue_buffers(struct efx_tx_queue *tx_queue,
 
         while (read_ptr != stop_index) {
                 struct efx_tx_buffer *buffer = &tx_queue->buffer[read_ptr];
-                if (unlikely(buffer->len == 0)) {
+
+                if (!(buffer->flags & EFX_TX_BUF_OPTION) &&
+                    unlikely(buffer->len == 0)) {
                         netif_err(efx, tx_err, efx->net_dev,
                                   "TX queue %d spurious TX completion id %x\n",
                                   tx_queue->queue, read_ptr);