1 files changed, 44 insertions, 0 deletions

diff --git a/drivers/net/ethernet/sfc/nic.c b/drivers/net/ethernet/sfc/nic.c
index b0baa70fbba7..d994d136bb03 100644
--- a/drivers/net/ethernet/sfc/nic.c
+++ b/drivers/net/ethernet/sfc/nic.c
@@ -20,6 +20,7 @@
 #include "farch_regs.h"
 #include "io.h"
 #include "workarounds.h"
+#include "mcdi_pcol.h"
 
 /**************************************************************************
  *
@@ -471,6 +472,49 @@ size_t efx_nic_describe_stats(const struct efx_hw_stat_desc *desc, size_t count,
 }
 
 /**
+ * efx_nic_copy_stats - Copy stats from the DMA buffer in to an
+ *	intermediate buffer. This is used to get a consistent
+ *	set of stats while the DMA buffer can be written at any time
+ *	by the NIC.
+ * @efx: The associated NIC.
+ * @dest: Destination buffer. Must be the same size as the DMA buffer.
+ */
+int efx_nic_copy_stats(struct efx_nic *efx, __le64 *dest)
+{
+	__le64 *dma_stats = efx->stats_buffer.addr;
+	__le64 generation_start, generation_end;
+	int rc = 0, retry;
+
+	if (!dest)
+		return 0;
+
+	if (!dma_stats)
+		goto return_zeroes;
+
+	/* If we're unlucky enough to read statistics during the DMA, wait
+	 * up to 10ms for it to finish (typically takes <500us)
+	 */
+	for (retry = 0; retry < 100; ++retry) {
+		generation_end = dma_stats[efx->num_mac_stats - 1];
+		if (generation_end == EFX_MC_STATS_GENERATION_INVALID)
+			goto return_zeroes;
+		rmb();
+		memcpy(dest, dma_stats, efx->num_mac_stats * sizeof(__le64));
+		rmb();
+		generation_start = dma_stats[MC_CMD_MAC_GENERATION_START];
+		if (generation_end == generation_start)
+			return 0; /* return good data */
+		udelay(100);
+	}
+
+	rc = -EIO;
+
+return_zeroes:
+	memset(dest, 0, efx->num_mac_stats * sizeof(u64));
+	return rc;
+}
+
+/**
  * efx_nic_update_stats - Convert statistics DMA buffer to array of u64
  * @desc: Array of &struct efx_hw_stat_desc describing the DMA buffer
  *	layout.  DMA widths of 0, 16, 32 and 64 are supported; where