[PATCH net-next 2/2] net: stmmac: TBS support for platform driver

[Rohan G Thomas]

Enable Time Based Scheduling(TBS) support for Tx queues through the
stmmac platform driver. For this a new per-queue tx-config property,
tbs-enabled is added to the devicetree.

Commit 7eadf57290ec ("net: stmmac: pci: Enable TBS on GMAC5 IPK PCI
entry") enables similar support for the stmmac pci driver.

Also add check whether TBS support is available for a Tx DMA channel
before enabling TBS support for that Tx DMA channel.

Signed-off-by: Rohan G Thomas <rohan.g.thomas@xxxxxxxxx>
---
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 25 +++++++++++++++----
 .../ethernet/stmicro/stmmac/stmmac_platform.c |  4 +++
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 81b6f3ecdf92..7333f0640b3d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3773,12 +3773,18 @@ stmmac_setup_dma_desc(struct stmmac_priv *priv, unsigned int mtu)
 		dma_conf->dma_rx_size = DMA_DEFAULT_RX_SIZE;
 
 	/* Earlier check for TBS */
-	for (chan = 0; chan < priv->plat->tx_queues_to_use; chan++) {
-		struct stmmac_tx_queue *tx_q = &dma_conf->tx_queue[chan];
-		int tbs_en = priv->plat->tx_queues_cfg[chan].tbs_en;
+	if (priv->dma_cap.tbssel) {
+		/* TBS is available only for tbs_ch_num of Tx DMA channels,
+		 * starting from the highest Tx DMA channel.
+		 */
+		chan = priv->dma_cap.number_tx_channel - priv->dma_cap.tbs_ch_num;
+		for (; chan < priv->plat->tx_queues_to_use; chan++) {
+			struct stmmac_tx_queue *tx_q = &dma_conf->tx_queue[chan];
+			int tbs_en = priv->plat->tx_queues_cfg[chan].tbs_en;
 
-		/* Setup per-TXQ tbs flag before TX descriptor alloc */
-		tx_q->tbs |= tbs_en ? STMMAC_TBS_AVAIL : 0;
+			/* Setup per-TXQ tbs flag before TX descriptor alloc */
+			tx_q->tbs |= tbs_en ? STMMAC_TBS_AVAIL : 0;
+		}
 	}
 
 	ret = alloc_dma_desc_resources(priv, dma_conf);
@@ -7505,6 +7511,15 @@ int stmmac_dvr_probe(struct device *device,
 		}
 	}
 
+	/* If TBS feature is supported(i.e. tbssel is true), then at least 1 Tx
+	 * DMA channel supports TBS. So if tbs_ch_num is 0 and tbssel is true,
+	 * assume all Tx DMA channels support TBS. TBS_CH field, which gives
+	 * number of Tx DMA channels with TBS support is only available only for
+	 * DW xGMAC IP. For other DWMAC IPs all Tx DMA channels can support TBS.
+	 */
+	if (priv->dma_cap.tbssel && !priv->dma_cap.tbs_ch_num)
+		priv->dma_cap.tbs_ch_num = priv->dma_cap.number_tx_channel;
+
 	ndev->features |= ndev->hw_features | NETIF_F_HIGHDMA;
 	ndev->watchdog_timeo = msecs_to_jiffies(watchdog);
 #ifdef STMMAC_VLAN_TAG_USED
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 843bd8804bfa..6c0191c84071 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -279,6 +279,10 @@ static int stmmac_mtl_setup(struct platform_device *pdev,
 		plat->tx_queues_cfg[queue].coe_unsupported =
 			of_property_read_bool(q_node, "snps,coe-unsupported");
 
+		/* Select TBS for supported queues */
+		plat->tx_queues_cfg[queue].tbs_en =
+			of_property_read_bool(q_node, "snps,tbs-enabled");
+
 		queue++;
 	}
 	if (queue != plat->tx_queues_to_use) {
-- 
2.26.2