sfc: add output flag decoding to efx_mcdi_set_workaround

The initial use of this will be to check a flag reporting if an FLR was
performed on other functions when enabling cascaded multicast filters.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/sfc/mcdi.c b/drivers/net/ethernet/sfc/mcdi.c
index 58232e7..98d172b 100644
--- a/drivers/net/ethernet/sfc/mcdi.c
+++ b/drivers/net/ethernet/sfc/mcdi.c
@@ -1779,15 +1779,31 @@
 	return rc;
 }
 
-int efx_mcdi_set_workaround(struct efx_nic *efx, u32 type, bool enabled)
+int efx_mcdi_set_workaround(struct efx_nic *efx, u32 type, bool enabled,
+			    unsigned int *flags)
 {
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_WORKAROUND_IN_LEN);
+	MCDI_DECLARE_BUF(outbuf, MC_CMD_WORKAROUND_EXT_OUT_LEN);
+	size_t outlen;
+	int rc;
 
 	BUILD_BUG_ON(MC_CMD_WORKAROUND_OUT_LEN != 0);
 	MCDI_SET_DWORD(inbuf, WORKAROUND_IN_TYPE, type);
 	MCDI_SET_DWORD(inbuf, WORKAROUND_IN_ENABLED, enabled);
-	return efx_mcdi_rpc(efx, MC_CMD_WORKAROUND, inbuf, sizeof(inbuf),
-			    NULL, 0, NULL);
+	rc = efx_mcdi_rpc(efx, MC_CMD_WORKAROUND, inbuf, sizeof(inbuf),
+			  outbuf, sizeof(outbuf), &outlen);
+	if (rc)
+		return rc;
+
+	if (!flags)
+		return 0;
+
+	if (outlen >= MC_CMD_WORKAROUND_EXT_OUT_LEN)
+		*flags = MCDI_DWORD(outbuf, WORKAROUND_EXT_OUT_FLAGS);
+	else
+		*flags = 0;
+
+	return 0;
 }
 
 int efx_mcdi_get_workarounds(struct efx_nic *efx, unsigned int *impl_out,